atw - International Journal for Nuclear Power | 03.2021

Ever since its first issue in 1956, the atw – International Journal for Nuclear Power has been a publisher of specialist articles, background reports, interviews and news about developments and trends from all important sectors of nuclear energy, nuclear technology and the energy industry. Internationally current and competent, the professional journal atw is a valuable source of information. www.nucmag.com

Ever since its first issue in 1956, the atw – International Journal for Nuclear Power has been a publisher of specialist articles, background reports, interviews and news about developments and trends from all important sectors of nuclear energy, nuclear technology and the energy industry. Internationally current and competent, the professional journal atw is a valuable source of information.



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ISSN · 1431-5254

32.50 €

Small Modular Reactor


and Perspectives

Nuclear Power is Dead,

Long Live Nuclear Energy!

BREST-OD-300 –

Demonstration of Natural

Safety Technologies

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atw Vol. 66 (2021) | Issue 3 ı May

Towards New Reactors and

Reactor Concepts

Nuclear energy is often referred to as “dinosaur technology” in discussions in order to characterize it in advance,

beyond a fair discussion. But even this is wrong, because the peaceful use of nuclear energy began about 70 years ago,

in the early 1950s, and it is thus virtually as young as, for example, renewable photovoltaics.

The first electricity from nuclear energy was generated in

1948 in an experimental facility. At the Oak Ridge National

Laboratory in the state of Tennessee in the USA, the X-10

reactor was commissioned in 1943 as the world's second

nuclear reactor after the Chicago Pile 1. From 1945, it

served research purposes and was also the first reactor in

the world to supply radioisotopes for medical use. The

air-cooled, graphite-moderated reactor offered a wide

range of possibilities for research but also technical

applications. In 1948, a small steam generator was

installed, the steam from which provided the drive for a

model generator that lit a light bulb for the first time in the

same year.

For the first time, electricity from a power plant

turbogenerator was supplied by the EBR-I fast reactor on

20 December 1951; four light bulbs marked the way to

further nuclear power generation.

Because of the many technical options and combinations

offered by nuclear fission, a wide variety of plant

concepts were pursued in the 1960s and 1970s, including a

broad range of applications. At an early stage, those

involved and developers were thinking not only of direct

power generation but also of district heating or the

provision of high-temperature process heat, seawater

desalination and chemical processes and energy storage –

all highly topical subjects today, for which experience

and historical documents from nuclear energy development

can provide valuable references, foundations and


As is well known, the developments around the

light water reactor technology have been commercially

successful until today, also because they could fall back on

manifold experiences of conventional power and energy

generation and provided a realizable potential with regard

to the further increasing plant capacities demanded at that


However, in these successful decades since the 1960s –

nuclear energy continues to be one of the most important

low-emission energy sources alongside hydropower, with

a share of around 11 % – other reactor concepts have never

completely lost their importance in research and development.

Comprehensive concept studies, such as the work of

the Generation IV International Forum (GIF) in the context

of "Generation IV," were essential in this regard. In 2002,

GIF published the so-called Technology Roadmap, which

describes six reactor types that are considered suitable for

achieving or meeting the development goals of safety,

sustainability and economic efficiency. But the work on

high-temperature reactor concepts or fast reactors in

China, India and Russia also underlines the continuity, up

to the construction and operation of real pilot plants.

When it comes to concepts for the future, a broad

spectrum of developments is on the agenda today. The

change in overall power generation, i.e. initially essentially

characterized by more renewable capacities with unsteady

and unpredictable power feed-in, also requires other

solutions for the indispensable “conventional” generation.

Ultimately, power plants or storage solutions must ensure

grid stability and security of supply.

Nuclear energy can advantageously cover a broad

power spectrum, if only because of its scalability. What is

new is how the U.S. Department of Energy classifies future

nuclear power plants according to their output into:

p Microreactors from 1 to 20 MWe(lectric)

p Small Modular Reactors – SMR from 20 to 300 MWe


p High-power reactors from 300 to 1,000 MWe.

These reactors would cover the currently foreseeable

demand for new and additional generation capacities in

the best possible way. The “microreactors” are newly

classified. Thus, their small footprint and an expected

construction time of no more than 24 months – DOE

expects 54 months for SMRs – make them appear suitable

for combination with high-capacity renewable generation

parks, where a source as close to site as possible is needed

to balance volatility.

However, new nuclear power plant developments also

require an appropriate regulatory environment and

infrastructure. Historical experience shows that quasisimultaneous

development of rules and regulations for

large-scale projects can lead to noticeable delays with their

planning, design, and construction. A coordinated and

systematic approach is needed here. The fact that a suitable

regulatory environment and a safe infrastructure for new

nuclear power plant projects can be set up and implemented

in a targeted and speedy manner is impressively

demonstrated by the four new nuclear power plants built

in the United Arab Emirates. Within just a decade from the

final construction decision until now, the commercial

commissioning of the first of four 1,400 MW nuclear power

plant units at the Barakah site, the necessary reliable

environment has been established. Also, worldwide, the

IAEA – International Atomic Energy Agency – today

supports 30 countries in building infrastructure for the

desired entry into peaceful use of nuclear energy – as a

sustainable, low-emission energy source with economic

and consumer-oriented generation.

Christopher Weßelmann

– Editor in Chief –




Towards New Reactors and Reactor Concepts

atw Vol. 66 (2021) | Issue 3 ı May




Issue 3




Towards New Reactors and Reactor Concepts . . . . . . . . . . . . . . 3

Inside Nuclear with NucNet

Lessons Learned

From the March 2011 Fukushima-Daiichi Nuclear Accident . . . . . 6

Calendar 8

Feature | Research and Innovation

Small Modular Reactor Safety-in-Design and Perspectives . . . . . . .9

Akira Tokuhiro, Chireuding Zeliang and Yi Mi


Site layout for the SMR nuclear site complex

by MOLTEX Energy. A feasibility report for Canada

with the MOLTEX concept under review has just been



2020-year-in review –

The NuScale Energy Exploration Center,

Copyright NuScale

Did you know? 17

Q&A with the Ministry of Natural Resources Canada

The Nuclear Innovation Policy of Canada . . . . . . . . . . . . . . . . 18

Interview with John Gorman

“I am Personally Very Excited About Canadas’s Positioning

as a Tier One Nuclear Power and also as a First Mover

in Small Modular Reactors“ . . . . . . . . . . . . . . . . . . . . . . . 21

Serial | Major Trends in Energy Policy and Nuclear Power

Nuclear Power is Dead, Long Live Nuclear Energy! . . . . . . . . . . 25

Simon Wakter

Energy Policy, Economy and Law

Europe on the Road to a Major Disaster . . . . . . . . . . . . . . . . 29

Herbert Saurugg

A Role for Nuclear in the Future Dutch Energy Mix . . . . . . . . . 35

Bojan Tomic and Mario van der Borst

Operation and New Build

BREST-OD-300 – Demonstration of Natural Safety Technologies . 41

Vadim Lemehov and Valeriy Rachkov

At a Glance

Nuclear Innovation Alliance (NIA) . . . . . . . . . . . . . . . . . . . . 46

Environment and Safety

Safety-related Residual Heat Removal Chains of German

Technology Pressure Water Reactors (Light and Heavy Water) . . 48

Franz Stuhlmüller and Rafael Macián-Juan

IAEA Approach to Review the Applicability of the Safety

Standards to Small Modular Reactors . . . . . . . . . . . . . . . . . . 56

Paula Calle Vives, Kristine Madden and Vesselina Ranguelova

Research and Innovation

A Zero-power Facility as a Multi-fold Opportunity to Support

Quick Progress in Innovative Reactor Development . . . . . . . . . 59

Bruno Merk, Dzianis Litskevich, Anna Detkina, Greg Cartland-Glover, Seddon Atknison and Mark Bankhead

The Thorium Network – An Introduction to Blockchain for SMRs . 65

Dian Kemp, Hulmo Christiaansen, Yvette Kemp and Jeremiah E. Josey

Kazatomprom’s Digital Transformation Projects . . . . . . . . . . . 68

Aliya Akzholova

Studies on Performance and Degradation Stability

of Chemically Degraded Nuclear Graded Ion Exchange

Materials by Application of Radio Analytical Technique . . . . . . 71

Pravin Singare

News 78

Nuclear Today

As Reactor Technologies Advance,

Nuclear Will Still Need its Environmental Champions . . . . . . . . 82

Imprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42


atw Vol. 66 (2021) | Issue 3 ı May



Research and Innovation

9 Small Modular Reactor Safety-in-Design

and Perspectives


Akira Tokuhiro, Chireuding Zeliang and Yi Mi

Interview with John Gorman

21 “I am Personally Very Excited About Canadas’s Positioning

as a Tier One Nuclear Power and also as a First Mover

in Small Modular Reactors“

Serial | Major Trends in Energy Policy and Nuclear Power

25 Nuclear Power is Dead, Long Live Nuclear Energy!

Simon Wakter

Energy Policy, Economy and Law

29 Europe on the Road to a Major Disaster

Herbert Saurugg

Operation and New Build

41 BREST-OD-300 – Demonstration of Natural Safety Technologies

Vadim Lemehov and Valeriy Rachkov

Environment and Safety

56 IAEA Approach to Review the Applicability of the Safety Standards

to Small Modular Reactors

Paula Calle Vives, Kristine Madden and Vesselina Ranguelova


atw Vol. 66 (2021) | Issue 3 ı May



Lessons Learned From the March 2011

Fukushima-Daiichi Nuclear Accident

The official Japanese report into the accident 10 years ago pointed to ‘a multitude of errors and

willful negligence’, but what steps have been taken to prevent a repeat?

Although triggered by a cataclysmic earthquake and

tsunami, the subsequent accident at the Fukushima-Daiichi

nuclear power station 10 years ago cannot be regarded as a

natural disaster.

It was, the Fukushima Nuclear Accident Independent

Investigation Commission concluded in its official report, 1 a

profoundly manmade disaster – one that could and should

have been foreseen and prevented. And its effects could

have been mitigated by a more effective human response.

Kiyoshi Kurokawa, chairman of the commission, was

blunt in his assessment of the root causes, pointing to a

multitude of errors and willful negligence that left the

Fukushima-Daiichi facility unprepared for the events of

11 March 2011. There were “serious deficiencies” in the

response to the accident by plant owner and operator Tokyo

Electric Power Company, regulators and the government.

Mr Kurokawa said what the commission’s report could

not fully convey – especially to a global audience – was the

mindset that supported the negligence behind this disaster.

“What must be admitted – very painfully – is that this

was a disaster ‘Made in Japan’, he said. “Its fundamental

causes were to be found in the ingrained conventions of

Japanese culture: our reflexive obedience; our reluctance

to question authority; our devotion to ‘sticking with the

programme’; our groupism; and our insularity.”

The report pointed to organisational problems within

Tepco. Had there been a higher level of knowledge,

training, and equipment inspection related to severe

accidents, and had there been specific instructions given to

the onsite workers concerning the state of emergency, a

more effective accident response would have been possible.

“Neither [Tepco or the regulators] had taken steps to

put preventive measures in place,” the report concluded.

“It was this lack of preparation that led to the severity of

this accident.”

The direct causes of the accident were all foreseeable.

The power station was incapable of withstanding the earthquake

and tsunami that hit on that day. The operator, Tokyo

Electric Power Company (Tepco), the regulatory bodies (the

Nuclear and Industrial Safety Agency and the Nuclear Safety

Commission) and the government body promoting the

nuclear power industry (the ministry of economy, trade and

industry, or METI), all failed to correctly develop the most

basic safety requirements – such as assessing the probability

of damage, preparing for containing collateral damage from

such a disaster, and developing evacuation plans for the

public in the case of a serious radiation release.

As early as 1981, NISA had required that nuclear

operators assess the anti-seismic safety of their sites

according to new guidelines – the so-called “anti-seismic


In March 2008, Tepco submitted an interim anti- seismic

backcheck report on Unit 5 of Fukushima-Daiichi, saying

the unit was safe.

In 2009, NISA accepted the contents of the interim

report, even though the scope of the assessment included

the reactor building and only seven of many other

important safety installations and equipment.

In June 2009, similar reports for Units 1 to 4 and 6 were

submitted, but these were similarly limited.

The official deadline for the backchecks was June 2009,

but according to the commission, Tepco made the decision

“internally and unilaterally” to reschedule the deadline to

January 2016.

Since 2006, the regulators and Tepco had also been

aware of the risk that a total outage of electricity at the

Fukushima Daiichi plant might occur if a tsunami were to

reach the level of the site. They were also aware of the risk

of reactor core damage from the loss of seawater pumps in

the case of a tsunami larger than assumed in the Japan

Society of Civil Engineers estimation. NISA knew that

Tepco had not prepared any measures to lessen or eliminate

the risk, but failed to provide specific instructions to

remedy the situation.

The report’s verdict on Tepco and the regulators was

damning. “They either intentionally postponed putting

safety measures in place, or made decisions based on their

organisation’s self-interest – not in the interest of public


An IAEA report 2 echoed these findings. It said a major

factor that contributed to the accident was the widespread

assumption in Japan that its nuclear power plants

were so safe that an accident of this magnitude was

simply unthinkable. This assumption was accepted by

nuclear plant operators and was not challenged by

regulators or by the government. As a result, Japan was not

sufficiently prepared for a severe nuclear accident in

March 2011.

“The Fukushima-Daiichi accident exposed certain

weaknesses in Japan’s regulatory framework,” the IAEA

said. “Responsibilities were divided among a number of

bodies, and it was not always clear where authority lay.”

The Response In Japan

Japan moved quickly to resolve serious problems around

nuclear regulation, safety and accident readiness.

The Nuclear Regulatory Authority was formed on

19 September 2012 from the Nuclear Safety Commission

(NSC), which came under the authority of the cabinet, and

the Nuclear and Industry Safety Agency (NISA), which was

under METI. The problem lay in the fact that METI was

also responsible for the promotion of nuclear power,

leading to accusations of a serous conflict of interest. The

NRA was established as an independent entity under the

environment ministry.

According to legislation establishing the NRA, new

nuclear safety rules were to be completed within

10 months. The NRA’s first chairman, Shunichi Tanaka,

1 https://www.nirs.org/wp-content/uploads/fukushima/naiic_report.pdf

2 https://www.iaea.org/sites/default/files/fr-brochure.pdf

Inside Nuclear with NucNet

Lessons Learned From the March 2011 Fukushima-Daiichi Nuclear Accident

atw Vol. 66 (2021) | Issue 3 ı May

said that the authority would undertake a radical review of

existing safety standards.

In January 2013 the NRA presented a draft outline of

new safety standards 3 for nuclear power plants, including

countermeasures against severe accidents and criteria for

evacuating areas around plants during an emergency.

The standards were approved in June 2013 4 and became

effective on 8 July 2013. The NRA began accepting

applications for reactor restarts. At this point only two of

Japan’s 42 commercial reactors, Ohi-3 and Ohi-4, had

restarted since the accident.

The standards consisted of severe accident measures

based on the accident at Fukushima-Daiichi, together with

design standards and requirements in each area of nuclear

plant safety.

Measures included a requirement to outfit plants with

backup control rooms away from reactor buildings, install

new pressure vents capable of filtering out radioactive

gasses, and reinforce protective structures.

Operators deployed movable alternative equipment

such as power supply vehicles so that plants could be

operated safely for at least seven days without outside help.

One of the severe accident measures was a requirement

to build a so-called “specific safety facility” on nuclear

plant sites, on the assumption of core damage in a reactor,

with terrorism a possible cause. Terrorism would include

an intentional aircraft strike.

The safety facility had to be situated 100 metres or more

from the reactor building, so it would not be destroyed in

the same event. A secondary control room was required

within the safety facility.

Mr Tanaka said the new rules represented “the

beginning of real [nuclear] regulation in Japan”.

The IAEA said Japan has reformed its regulatory system

to better meet international standards. Regulators have

clearer responsibilities and greater authority. The new

regulatory framework has been reviewed by an IAEA peer

review mission. Emergency preparedness and response arrangements

have also been strengthened, the agency said.

Japan’s Nuclear Status

Japan has 62 nuclear power units, but shut down all 42

that were operating at the time after Fukushima-Daiichi.

Thirty-three units have a licence to operate, although

before units return to service they need to meet the NRA’s

new safety standards.

Nine units have been returned to service, but five of

those are offline again for regular maintenance or

upgrades. The four reactors that are online are Sendai-1,

Sendai-2, Genkai-3 and Ohi-4.

Before the Fukushima-Daiichi accident Japan’s nuclear

fleet generated about 30 % of the country’s electricity.

According to the International Atomic Energy Agency that

figure was about 7.5 % in 2019.

Governments with established nuclear-energy

programmes responded in part by conducting safety

checks, including comprehensive “stress tests” that

scrutinised a facility’s ability to withstand everything from

an earthquake and tsunami to a terrorist assault.

Additional backup sources of electrical power and

supplies of water have been installed, and protection

against extreme external events strengthened. In some

cases, organisational and regulatory systems have been


Safety reassessments concluded that facilities examined

offer a safety level that is sufficient, and no immediate

shutdown was required.

The IAEA emphasises that nuclear safety remains the

responsibility of an individual country, but says nuclear

accidents can transcend borders and the Fukushima-

Daiichi accident “underlined the importance of international


In Europe, all nuclear power plants in the EU underwent

stress tests and peer reviews in 2011 and 2012. Many

other countries and territories also conducted comprehensive

nuclear risk and safety assessments, based on

the EU stress-test model. These include Switzerland and

Ukraine (both of which fully participated in the EU stress

tests), Armenia, Turkey, Russia, Taiwan, Japan, South

Korea, South Africa and Brazil.

In China, which had aspirations to build up to 100 new

nuclear units by 2030, plans were put on hold. Premier

Wen Jiabao announced the suspension of the approval of

new nuclear power projects and called for a com prehensive

safety assessment of Chinese nuclear power facilities.

Beijing ultimately decided to lift the moratorium on

construction of new nuclear power plants in October 2012.

The state council said safety investigations had shown that

“nuclear security is guaranteed in China.”

In the US, the Nuclear Regulatory Commission ordered

in March 2012 that nuclear power plants meet specific

deadlines for safety checks and upgrades. 7

The checks

included maintaining key safety functions even if installed

electricity sources fail; installing additional equipment to

monitor spent fuel pool water levels; and installing or

improving systems to safely vent pressure during an

accident. The NRC also asked all US plants for information

on comprehensive earthquake and flooding hazard



David Dalton

NucNet –

The Independent Global Nuclear News Agency

Bruxelles, Belgium



The International Response

Three months after the accident, the International Atomic

Energy Agency hosted a ministerial conference on nuclear

safety. This paved the way for the unanimous endorsement

of an IAEA action plan 5

that has led to international

collaboration toward strengthening global nuclear safety. 6

3 https://www.nucnet.org/news/japan-s-regulator-unveils-proposed-new-safety-measures

4 https://www.nucnet.org/news/japan-s-regulator-approves-new-safety-guidelines

5 https://www.iaea.org/topics/nuclear-safety-action-plan

6 https://www.iaea.org/newscenter/news/four-years-of-progress-action-plan-on-nuclear-safety

7 https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/japan-events.html

Inside Nuclear with NucNet

Lessons Learned From the March 2011 Fukushima-Daiichi Nuclear Accident

atw Vol. 66 (2021) | Issue 3 ı May





Online Conference 04.05.2021

2021 KTG Annual Meeting. Berlin, Germany, KTG,


Online Conference 10.05. – 15.05.2021

FEC 2020 – 28 th IAEA Fusion Energy Conference.

Nice, France, IAEA, www.iaea.org

18.05. – 20.05.2021

Power Uzbekistan 2021 – 15 th Anniversary

International Exhibition on Energy.

Tashkent, Uzbekistan, Iteca Exhibitions,


Online Conference 04.08. – 06.08.2021

ICONE 28 – 28 th International Conference on

Nuclear Engineering. Nuclear Energy the Future

Zero Carbon Power. ASME, https://event.asme.org

25.08. – 27.08.2021

KONTEC 2021 – 15 th International Symposium

“Conditioning of Radioactive Operational &

Decommissioning Wastes”. Dresden, Germany,

atm, www.kontec-symposium.de

25.08. – 03.09.2021

The Frédéric Joliot/Otto Hahn Summer School

on Nuclear Reactors “Physics, Fuels and Systems”.

Aix-en-Provence, France, CEA & KIT, www.fjohss.eu

29.08. - 03.09.2021

PSA 2021 – International Topical Meeting on

Probabilistic Safety Assessment and Analysis.

ANS, Columbus, OH, USA, www.psa.ans.org

Postponed to 24.10. – 28.10.2021

TopFuel 2021. Santander, Spain, ENS,


26.10. – 28.10.2021

VGB Conference Chemistry. Ulm, Germany, VGB

PowerTech, www.vgb.org

01.11. – 12.11.2021

COP26 – UN Climate Change Conference.

Glascow, Scotland, www.ukcop26.org

Postponed to 30.11. – 02.12.2021

Enlit (former European Utility Week and

POWERGEN Europe). Milano, Italy,


30.11. – 02.12.2021

WNE2021 – World Nuclear Exhibition. Paris,

France, Gifen, www.world-nuclear-exhibition.com

Postponed to 30.08. – 03.09.2021

International Conference on Operational Safety

of Nuclear Power Plants. Beijing, China, IAEA,



Online Conference 19.05. – 20.05.2021

Small Modular Reactors (SMR). Prospero,


Cancelled due to COVID 30.05. – 05.06.2021

BEPU2020 – Best Estimate Plus Uncertainty

International Conference, Giardini Naxos.

Sicily, Italy, NINE, www.nineeng.com

Online Conference 07.09. – 09.09.2021

Management systems for a sustainable nuclear

supply chain. Helsinki, Finland, Foratom,


Hybrid Conference 08.09. – 10.09.2021

3 rd International Conference on Concrete

Sustainability. Prague, Czech Republic, fib,


08.09. – 10.09.2021

World Nuclear Association Symposium 2021.

London, UK, WNA, www.wna-symposium.org

Postponed to 28.02. – 04.03.2022

20 th WCNDT – World Conference on

Non-Destructive Testing. Incheon, Korea,

The Korean Society of Nondestructive Testing,


06.03. – 11.03.2022

NURETH19 – 19 th International Topical Meeting

on Nuclear Reactor Thermal Hydraulics. SCK·CEN,

Brussels, Belgium, www.events.sckcen.be

22.09. – 23.09.2021

VGB Congress 100 PLUS. Essen, Germany, VGB

PowerTech, www.vgb.org

Online Conference 01.06. – 02.06.2021

Nuclear Power Plants IV. Expo & VIII. Summit

(NPPES). Istanbul, Turkey, INPPES Expo,


Online Conference 02.06. – 05.06.2021

HTR2021 – 10 th International Conference

on High Temperature Reactor Technology.

Yogyakarta, Indonesia, Indonesian Nuclear Society,


Online Conference 07.06. – 09.06.2021

Nuclear Energy Assembly. NEI,


Online Conference 14.06. – 16.06.2021

2021 ANS Annual Meeting. ANS, www.ans.org

26.09. – 30.09.2021

RRFM 2021 – European Research Reactor

Conference. ENS, Helsinki, Finland,


27.09. – 30.09.2021

European Nuclear Young Generation Forum

(ENYGF). Tarragona, Spain, ENYGF, www.enygf.org

27.09. – 01.10.2021

NPC 2021 International Conference on Nuclear

Plant Chemistry. Antibes, France, SFEN Société

Française d’Energie Nucléaire,


04.10. – 05.10.2021

AtomExpo 2021. Sochi, Russia, Rosatom,


29.03. – 30.03.2022


Leipzig, Germany, KernD and KTG,


04.04. – 08.04.2022

International Conference on Geological

Repositories. Helsinki, Finland, EURAD,


Postponed to Spring 2022

4 th CORDEL Regional Workshop – Harmonization

to support the operation and new build of NPPs

including SMR. Lyon, France, World Nuclear

Association, https://events.foratom.org

Online Conference 23.06. – 24.06.2021

Maintenance in Power Plants 2021.

VGB PowerTech e.V., www.vgb.org

Online Conference 20.07. – 22.07.2021

POWER 2021. ASME, www.event.asme.org

Online Conference 03.08.-04.08.

and 10.08.-11.08.2021

International Uranium Digital Conference 2021.

AusIMM, www.ausimm.com

Postponed – final date and location

to be determined

ICEM 2021 – International Conference on

Environmental Remediation and Radioactive

Waste Management. ANS, www.asme.org

16.10. – 20.10.2021

ICAPP 2021 – International Conference on

Advances in Nuclear Power Plants. Khalifa

University, Abu Dhabi, United Arab Emirates,


Postponed to 04.05. – 06.05.2022

NUWCEM 2022 – International Symposium on

Cement-Based Materials for Nuclear Wastes.

Avignon, France, SFEN, www.sfen-nuwcem2021.org

This is not a full list and may be subject to change.


atw Vol. 66 (2021) | Issue 3 ı May

Small Modular Reactor

Safety-in-Design and Perspectives

Akira Tokuhiro, Chireuding Zeliang and Yi Mi

Across the public, nuclear power and global energy sectors, there are various degrees of interest in next and

near-generation micro- to small, modular reactors (MMR, SMR) 1 . The ongoing interests, here defined in terms of

commercial and national technology developments, policy documents (roadmaps, action plans, etc.), various levels

and means of “investments”, are intended to support and facilitate development of select advanced reactor concepts

and demonstration units. The current portfolio of SMRs and MMRs is relative to the current, global fleet; mostly larger

scale nuclear plants (Generation III and III+ designs) currently under construction and/or operating. These legacy

designs largely meet the electricity demand in nations with robust socio-economic development rates. Both the

operating plants and those in various stages of development are included in a “pan-global, nuclear portfolio”, touted (in

the “24/7/365” social media) to address and mitigate the negative impacts of climate change. While there are reasons

to “worry” about the lack of foresight, preventative preparedness and response to address the cliff-edge impacts of climate

change, the goal here is not to argue climate change nor policies/developments in national commitments to a

lower or net-zero carbon economies of scale. If anything, climate change can be construed as human society’s inability

to exercise a paradigm shift – in effect, a linear extrapolation from 150+ years of industrialization based on fossil fuels

and release of effluents without consequences. Along the way, we forgot to ask what can happen and how can it happen.

The consequences are here and imminent (“urgent”), as expressed by climate change leaders, Greta Thunberg, and

others. Nature is suffering in our age of our Anthropocene.

With this in mind, the article here will review a number of

ongoing micro- to small, modular reactors concepts, but

from the perspective of engineering and design development

so that the design is completed. While engineered

and designed features hold much interest to those with

engineering and R&D backgrounds, one might argue that

if nuclear energy is to serve in transition and/or as a

solution to aspirational economies of scale that mitigate

and reduce the negative impacts of climate change, nuclear

reactor designs need to be complete, prudently financed

and “constructable”, because ultimately they serve to

generate electricity that the public expects and demands.

Some 70 years ago in nuclear history, then U.S. President

Dwight Eisenhower appeared at the United Nations (1953)

and spoke on, “Atoms for Peace”. Subsequently, in the then

short list of post-WWII developed and developing nations,

there was rapid development, and selection process of

Generation I and II nuclear concepts. Many of these are

part of the 440 or so nuclear power plants operating today.

1 Designs, Legacy and Processes

A few words about the design and engineering process of

new/advanced reactor concepts is in order. Perhaps owing

to the lead author’s educational legacy, it is not something

that I remember explicitly learning during my nuclear

engineering education. That said, there are established

processes within nuclear vendors (manufacturers) that

remain proprietary. These practices do not necessarily

make it into university classrooms. My observation has

been that seasoned professionals from the nuclear sector

do not transition late in their career, to university nuclear

engineering programs/classrooms. There can thus be a

knowledge transfer gap, from the reactor vendor to the


The article here on advanced reactor concepts and

SMRs/MMRs, is based on the assumption that completing

the design is of utmost importance, and that the design

process takes time and requires sufficient and sustained

funding because the key high-level task is, iterative

system design. That is, engineering system design, wherein

systems and subsystems are coupled, require iterative

design optimization. This is certainly the case in nuclear

reactor design.

So, we note that SMRs, like many nuclear reactors are

generally designed from the reactor core, outward in terms

of various essential and supporting systems; that is, the

primary, secondary systems and beyond. In fact, one could

say for SMRs, the design regions of interest extend all the

way to the emergency planning zone (EPZ), since in

principle, a SMR’s EPZ should be related to, “very

small probability (keep reading) but a high consequence”,

hypothetical accidents. One can say that increasingly

Generation IV (or advanced) reactor concepts are expected

to have very small hypothetical probability with respect to

design basis and beyond design basis accidents (DBA,

BDBA), and features that substantiate means to address

Fukushima (Daichi) type situations. In fact, the design

itself is expected to have a number of safety-in-design

features so that the commonly cited metrics such as, “core

damage frequency” (CDF) and/or “early release frequency”

(ERF), are typically, smaller than 1E-06 2 , if not 1E-08. (We

note here that probabilities – less than say, 1E-09, 1E-10 or

smaller may not hold regulatory meaning or significance.)

Further, other than these small probabilities, observance

or adherence to safety-in-design philosophies/principles

as described in INSAG-10 [14], and “goodness” in design

such that no human intervention is required for durations

of time beyond “event” initiation (i.e. first 24, 48, 72 hours,

etc.), detailed information on accident progression/

evolution, may appear as aspirational or embedded in the

design features and functions, without open access to the

technical details. Open access of detailed technical

information may not be possible; thus, it is not current


With the above design engineering process and metrics

in mind, let us look at the micro- to small modular reactor



1 The term, SMR, is used to be inclusive of Small and Micro Modular Reactor concepts and designs.

2 This notation is used instead of a superscript that may appear visibly small (1 x 10 -6 ).


Small Modular Reactor Safety-in-Design and Perspectives ı Akira Tokuhiro, Chireuding Zeliang and Yi Mi

atw Vol. 66 (2021) | Issue 3 ı May


concepts currently under various states of development.

We note that since a number of overview articles on SMR/

MMR reactor concepts exist, this article is not intended to

be such. Instead we thought to reveal some of the not so

obvious aspects of safety-in-design, that various advanced

reactor designers may adopt to varying degrees. First for

brevity and utility, we cite some of the key documents

below as a starting point into the various aspects

surrounding SMRs as follows:

p On safety-in-design, references [1, 7, 14, 17(US only),

23, 24, 30]

p On licensing and regulatory aspects of SMRs, reference

[3, 15, 19, 22]

p Overview and advances of SMR, reference [2, 6, 9, 16,

31, 33, 36, 40]

p Specifically passive safety systems within safety-indesign,

references [8, 20, 32]

p Nuscale, SMART, IRIS, CAREM, ESBWR, AP1000

specific starting documents, reference [10, 11, 12, 13,

21 (NuScale EPZ), 28, 29]. Note that the ESBWR and

AP1000 are Generation III/III+, large-scale plant

designs from which lessons learned are realized in SMR


p General principles in nuclear design and economics,

references [4 (economics),18, 25, 26]

2 Back to the future with nuclear energy?

In a manner similar to many early nuclear reactor

concepts in the late 1950s, early 1960s, there are many

micro- to small, modular reactor concepts. However, with

approximately 60 years of complete design experience,

operational experience, lessons learned from three major

severe accidents, (along with other recorded events),

unrestrained cost increases, regulatory compliance burdens,

anti-nuclear sentiments and advances in computer- based

engineering, recent advanced reactor designs hold consensus

expectations in safety, non- proliferation and

economics. It goes without much declaration that nuclear

energy is often questioned and compared to other forms of

energy (including renewable energy sources) and as a

matter of regional to national energy policy. In recent years,

public acceptance of any risk-inherent technology, processes,

production and consumption – a composite portfolio

of social license, advocacy and questionable objectivity

issues, are fiercely fought with fervent banter in social

media domains. Everyone has an opinion.

Nuclear energy and new micro- to small, modular

reactor concepts are not benign from socio-technical

scrutiny, most recently in the global debate on whether

nuclear energy is a partial to full solution to counter the

increasingly emerging evidence on the negative impacts of

climate change.

2.1 The micro- to small, modular reactor


Nuclear reactors are traditionally classified in terms of the

following technical features. These features are high-level

decisions made by its originators. They are: 1) neutron

spectrum, 2) related type of neutron moderation, 3) type

of coolant, 4) fuel type and core configuration. We will use

the same approach for consistency. We note Hussein [40]

review that used an expanded classification based on

200+ cited references.

We limit our coverage below to SMR design concepts

of thermal power (output) magnitude that feature conventional

or unique energy conversion system design, utilizing

a liquid-based energy transport system from a defined core

configuration. The core and energy transport system

should fulfill the basic functions as follows: startup (to

criticality), (transition to) steady-state operation at a

targeted power, transition up or down from a given power

setting to another, intended shutdown, emergency shutdown

and post-shutdown decay heat energy removal (to

cold shutdown state).

In this regard, micro-modular reactor concepts (MMR)

are even simpler in design than many SMR concepts

because the thermal power output is approximately an

order of magnitude smaller than SMR (i.e. ~O (5 MWth)

per reactor core vs. ~O (50 MWth)) per reactor core] and

as such, the corresponding means of reactivity control are

reduced accordingly. With respect to MMR safety-indesign,

post-shutdown energy removal mechanisms are

predominantly passive such that air or a large volume of

water, serves as the ultimate heat sink for decay heat.

Energy conversion systems are correspondingly modular

in design and may feature reduced coupling to reactor core

control (and thus operations) such that the sole output is

electricity and/or thermal energy. With such simple design

and limited functions, the thermal-hydraulic “parameter

space” is correspondingly small, such that conventional

means of control (analog and/or digital) can be used for

monitoring, prognostics and diagnostics. The 2020 release

of the IAEA “book” on SMRs/MMRs contains 6 MMR concepts.

A concise, descriptive summary of the announced

MMR concepts is given below.

1) Energy Well (Rez, Czech Republic) – is a high

temperature (core inlet, 650 °C; outlet, 700 °C) molten

salt FLiBe cooled and moderated, with targeted thermal

and electrical power output, 20MWt/8 MWe. The once

through core design features 15 % enriched TRISO fuel

and operational reactivity control via Y-shaped control

rods. Energy conversion is a 3-loop (FLiBe, NaBF 4 ,

supercritical CO 2 ) design so as to avail pro duction of

electricity, hydrogen and energy storage, juxtaposed

against the Czech national energy portfolio. Common

to many national nuclear conceptual design engineering

studies (here at nuclear R&D centre, Rez), while

development details may be ongoing, a path toward

commercialized deployment is unknown.

2) MoveLuX (Toshiba, Japan) – is a sodium heat-pipe

cooled and calcium hydride moderated, natural

convection (air-based primary circuit) driven MMR

with thermal/electrical power output, targeted at

10 MWt/3-4 MWe. The core design uses uranium

silicide (U 3 Si 2 ) fuel housed in hexagonal “cans” with

lithium expansion system reactivity control. With a

sodium heat pipe based higher temperature conversion

system coupled to helium gas, electricity and hydrogen

production are possible, as well as a fuel cycle adapted

to the national fuel cycle practice. This MMR concept is

a Toshiba internal conceptual design study.

3) U-Battery (Urenco, UK) – is a high-temperature, helium

gas-cooled, graphite-moderated MMR with targeted

thermal/electrical output, 10 MWt/4 MWe. The core

design uses TRISO fuel, enriched up to 20 %, in

hexagonal blocks with control rods, fixed burnable

poisons and shut-down absorber spheres. A 5-year full

power year and 30-year design life are targeted. Energy

conversion is via indirect secondary nitrogen circuit

with applications both for heat applications or closed

gas-turbine technology (no combustion stage).

Regulatory approval of its detailed design and

commercialization partners have been announced by

its developer, URENCO – UK.


Small Modular Reactor Safety-in-Design and Perspectives ı Akira Tokuhiro, Chireuding Zeliang and Yi Mi

atw Vol. 66 (2021) | Issue 3 ı May

4) AURORA – (Oklo, USA) – with a targeted thermal/

electric power output, 4 MWt/1.5 MWe, this compact,

liquid-metal cooled fast reactor MMR using metal fuel,

a 20-year refueling cyle, Oklo has applied for a USNRC

combined license application. The plant features low

power output, low power density and low decay heat

output, and correspondingly has low fuel burnup, small

fuel inventory, simplicity in energy removal by inherent

and passive means, and overall takes advantage of

thermal capacity via use of higher con ductivity material

selection. Oklo has an existing agreement to access

the Idaho National Lab site and some aspects of their

technology know-how under a partnership agreement.

5) eVinci Micro Reactor (Westinghouse, USA) – this

conceptual design MMR with a targeted thermal/

electrical power output, 7-12 MWt/2-3.5 MWe, uses

(sodium) heat pipes and metal hydride moderator in a

stand-alone, transportable reactor and energy conversion

system unit. Instrumentation and controls are

provided via a separate, integrated (second) unit. The

core is based on TRISO or similarly encapsulated fuel,

in a monolithic core with reactivity control realized via

ex-core (moving) control drums. Onsite refueling or

whole reactor replacement are envisioned. Energy

conversion is via open-air Brayton and single shaft gas

turbomachinery. The core is designed with negative

reactivity, and decay heat removal is via intended

conduction and natural convective heat dissipation to

air. The design integrates many elements and simplifications

based on lessons learned by Westinghouse in

overall plant “island” design. The design concept is

under Vendor Design Review, Canadian Nuclear Safety

Commission (CNSC), and preliminary discussions with

the USNRC.

6) MMR (Ultra Safe Nuclear, USA) – this MMR with a

( Canadian) national laboratory site partnership

permit, has a targeted thermal/electrical power ouput,

15 MWt/greater than 5MWe. This MMR is a hightemperature,

(helium) gas-cooled, graphite- moderated,

solar salt energy stored integral design. The core will

use TRISO for fully ceramic micro-encapsulated (FCM)

fuel pellets, HALEU enriched to just under 20 %, in

hexagonal blocks with control rods. Its inherent core

negative temperature feedback and low power density,

dissipates heat radiatively and via natural convection.

Energy conversion is via a 3-loop system with a molten

salt intermediate (heat exchanger) loop that also stores

thermal energy. This loop connected to a steam

generator unit. The concept, under Global First Power,

has submitted a license to prepare site initial application

at CNL Chalk River site, and with the CNSC.

various designs are most clearly revealed in the thermalhydraulic

design that minimize and/or eliminate potential

initiating events may be linked to DBA and certainly BDBA

scenarios. In the latter case, the DBA/BDBA can then be

claimed as impossible. Reflection of this approach then

begs the question of prudent integration of the following

practices: probabilistic risk assessment (PRA), system

analysis ( RELAP and similar), accident analysis (MELCOR

and similar) and dispersion analysis. The work by Williams

et al. [34] describes the safety-in-design, including foremost,

defense-in-depth and putting into (design) practice,

the INSAG-10 explicit levels.

2.3 Gas-cooled, graphite-moderated

Large scale gas-cooled, often graphite-moderated reactors

have a history as long as water-cooled, thermal spectrum

reactors. As such, there have been generational reactor

concepts paralleling that of LWRs. Much of the

generational development can be traced to the 1950s to

1970s, and is associated with the prismatic (block) type

Magnox and AGR in the UK [41, 42]. The pre-commercial,

experimental Dragon reactor introduced the TRISO

(tristructral- isotropic) fuel type. Soon thereafter, the

German constructed and operated the AVR (Arbeitsgemeinschaft

Versuchsreaktor), with a pebble bed fuel and

moderator (spheres) core configuration, demonstrated

high- termperature operation using gas as coolant. This

reactor concept is often attributed to Daniels and Schulten,

and following the AVR saw incremental developments via

the following: German THTR-300, the Japanese High

| Figure 1

U-Battery Design (Source: www.u-battery.com/design-and-technology).


2.2 Water-cooled, moderated, thermal spectrum


Due to the large number of light water-cooled, thermal

spectrum reactor designs in the history of nuclear energy,

SMRs based on the similar light water moderation,

reflection and cooling concepts comprise the largest

grouping of SMR concepts and designs at present. In fact,

one of the most complete, if not the only completed design

is that by NuScale Power. Not surprisingly, many aspects of

the design, engineering, system design and overall, design

methodology are proprietary. That said, based on a survey

of various SMR designs of integral Pressurized Water

Reactor type (iPWR) by Zeliang, Mi and co-workers [32], if

the selected core design is conventional (primarily to

reduce overall cost), but smaller, then differences in

| Figure 2

The Micro Modular Reactor (MMR) system (Source: www.usnc.com/mmr-energy-system/).


Small Modular Reactor Safety-in-Design and Perspectives ı Akira Tokuhiro, Chireuding Zeliang and Yi Mi

atw Vol. 66 (2021) | Issue 3 ı May


| Figure 3

Westinghouse eVinci Micro Reactor

(Source: www.westinghousenuclear.com/new-plants/evinci-micro-reactor).

Temperature Test Reactor (HTTR) and Chinese High

Temperature Reactor, HTR-10. X-Energy’s Xe-100 is the

current pebble-bed, high temperature, gas-cooled nuclear

reactor (SMR) design, using TRISO fuel and with targeted

output at 200 MWth/76 MWe. Consistent with many light

water based SMR designs, the current day gas-cooled,

graphite based concepts feature active or passive safety


2.4 Unique Reactor Designs

There are and can be other unique types of SMRs and

MMRs designs and concepts, differing in selection of fuel

type, fuel form (solid vs. liquid), neutron energy spectrum,

the combination of coolant, moderator and reflector,

thermal/electrical output, safety-in-design and deployment

strategies, including aspects of modularity, manufactureability,

cost savings per advance manu facturing

methods, and “add-on” benefits such as medical isotope,

hydrogen and district heating production. It may be

reasonable to say that, assuming that there is ( sovereign)

regulatory review with inclusion of public consultation of

any particular SMR design, aspects of technical innovation

and interest, has to prevail against public sentiment and

skepticism. Thus, innovative concepts rarely have a chance,

even in demonstration, and in today’s social media driven,

multi-national climate, consensus acceptance may be

needed for certain. In other words, new technology

solutions have to overcome a daily battle of disinformation

and misinformation to garner and secure sustainable

investments and developments. In other words, “the odds

are not very good, even if the technology (the goods) are

very innovative (not odd)”.

2.5 Molten salt-fueled and cooled,

and fast spectrum, liquid metal designs

As noted, finishing the SMR design and submitting this for

regulatory review and approval, as well as commitment to

construction via sufficient and satisfactory investments,

are the most important in current SMR efforts. These

linked objectives also apply to novel SMR/MMR concepts

based on molten-salt fueled and cooled concepts as well as

fast spectrum concepts. Historically and technically, fast

spectrum concepts are often associated with liquid metal

(sodium, lead, eutectic alloys, etc.) thermal-hydraulic

system designs. Most notably, large thermal diffusivity

(and conductivity, relative to water) and selection of

materials with small neutron cross section, provide design

advantages in fast spectrum concepts. A succinct summary

of the sodium-cooled fast reactor is contained in [43]. The

IAEA “2020 booklet” provides technical specification of

the Terrestrial Energy’s [39] and Kairos Power’s (fluoride

salt-cooled, high temperature, pebble bed), [40] designs,

as well as the fast spectrum designs of the ARC-

100 (sodium- cooled) and Oklo (MMR, HALEU fuel,

supercritical CO 2 with heat pipe) concepts. Additional

information of technical interest can be found via ongoing

regulatory review processes (examples: US, Canada) and

open access publications and news releases. Of importance,

relative to and in contrast to thermal spectrum SMR/

MMRs with safety-in-design, is the inherently passive

safety system feature (including reactivity control) corresponding

to a defense-in-depth approach, that provides

competitive, if not advantageous benefit, in the eyes of the

stakeholders. Because these reactor concepts are or can be

significantly different than thermal spectrum, water-based

SMR/MMR designs (example, flowing in-solution liquid

fuel and coolant), they provide important regulatory

opportunity to confirm technology “neutrality” when that

objective is sought.

There are 11 fast spectrum SMR concepts noted in the

IAEA – 2020 book. Of these, the Siberian Chemical

Combine’s, BREST-OD-300, with declared thermal and

electrical power output, 700 MWt/300 MWe, recently

received license (from Rostechnadzor) to be constructed

in Seversk. This, a lead (Pb-cooled and moderated, pool

type fast reactor, is both a test and demonstration plant. It

is thus an evolutionary design similar in design to French

and Japanese one-off SFR designs (Super Phenix, Joyo,

Monju), but incorporating lessons learned using lead and

lead-bismuth within the Russian Federation. The core

consists of mixed uranium-plutonium nitride fuel,

enriched up to 14.5 %, in hexagonal configuration with

chromium ferritic-martensitic steel cladding and capability

for fuel breeding. Reactivity control is via shim and automatic

control roads, while the 2-loop energy conversion

system features a lead to water steam generator system.

The emergency core cooling system is passive, and consists

of pipes immersed directly into the primary system, thus

serving as a natural circulation driven lead-to-air heat

exchanger. Completion of construction is scheduled to be

as early as 2026.

It is worth noting that in terms of safety-in-design of

liquid-metal cooled fast reactors, the key safety feature is a

prompt, negative temperature feedback from Doppler

broadening of the cross section. In simple terms, because

of the combination of higher fuel enrichment (relative to

water-cooled reactors), liquid metal as coolant and

subsequent compactness of the overall core design, the

power density of a fast reactor is larger than water-cooled

reactors. Thus, the probability of an initiating event

developing into an energetic event has to be considered.

The safety-in-design of the EBR-II test/demonstration

plant considered many of these aspects and demonstrated

its inherent safety. In brief, historically documented

( accident) phenomena specifically for sodium-cooled

designs include the following: transient overpower, lossof-flow,

fuel- vapor explosion, sodium vapor explosion,

containment response under short and sustained loads.

For specific liquid metal cooled, SMR-scale fast spectrum

designs, these specific issues have to be addressed.

It remains to be seen how the ARC-100 SFR will develop

as a scaled-down, updated version of EBR-II [44], with

some of the original EBR-II lead principals. The ARC-100 is

a forced circulation SFR, thermally projected to be

286 MWt/100 MWe, and featuring U-Zr metallic fuel,

enriched on average to 13.1 %, such that it has a 20-year

refueling service life. Beyond the primary circuit, it

features a 2-loop IHX to SG design, supported by four

submersed EM pumps. The SG is a vertically oriented,

helical coil, single-walled, counter-flow sodium-to-water,

shell-in-tube design. Reactivity control is via a redundant


Small Modular Reactor Safety-in-Design and Perspectives ı Akira Tokuhiro, Chireuding Zeliang and Yi Mi

atw Vol. 66 (2021) | Issue 3 ı May

system of 6 control rods (3 x 2). Besides the core, many of

the major energy conversion system components are

integrated into the reactor vessel and defining building.

The ARC-100 is undergoing CNSC Vendor Design Review

and has Provincial support from New Brunswick ( Canada).

Generational knowledge preservation and transfer, as well

as workforce capability to understand the SFR remains to

be seen.

Finally, we would be remiss if the long-standing promise

of fast reactors as part of national energy self-sufficiency

strategy via closing of the nuclear fuel cycle, is not noted.

Unfortunately, no nuclear nation today completely

practices a fully closed (commercial) nuclear fuel cycle

and thus, with fast reactors of a SMR “kind”, we have to

again maintain a sensible view to technology readiness of

fuel reprocessing aspects for those fast SMR concepts that

use existing supplies of spent fuel. Except possibly in China

and the Russian Federation, openly competitive global

markets have eroded the promise of fast reactors and

closed fuel cycle.

3 Lesson learned, evolution of

safety-in-design, getting to the end

One can look at the 70+-year history of nuclear power

generation of electricity, and relative to other public use/

acceptance of other risk-inherent technologies such

as the automobile and travel via commercial airlines

(approximately 100 years), begin to understand the

development of social license/public acceptance of

technologies. Once could state that unfortunately, nuclear

power developed alongside environmental consciousness

and a spectrum of “anti” movements that continue to this

day. This paper is not intended to argue rightful acceptance

of nuclear power. However, not preserving the options

presented by nuclear generated electricity would be

testimony to lack of foresight in the world we live in today,

with the issues and challenges that we have.

The ongoing “nuclear renaissance” of recent years can

be summarized in terms of the following trends: 1)

conceptual designs followed by various states of

engineering design development of many types of SMRs

and MMRs, 2) a broad discussion of the socio- technological

importance of addressing (the emerging, negative impacts

of) climate change, and thus, transitioning away from a

carbon-based (fossil fueled) to low carbon or net zero

carbon economies of scale using nuclear energy, and 3) unbeknownst

to many but integration of lessons learned,

evolution in safety-in-design thinking, and advancements

in modeling and simulation (using high performance

computing) for advanced reactor designs. Recent

advancements in accident tolerant fuels, and advanced

manufacturing are noted but perhaps years away from

being inherent in SMR/MMR design.

4 Emerging drivers in SMR and

advanced reactor concept design

The ongoing global interest and enthusiasm for SMR/

MMR has generated many concepts but equally revealed

uncoordinated global gaps, including regulatory review of

the safety-in-design of various concepts. This is to be

expected, given that regulatory mandate is at the national

level. That said, there are a few bi-/tri-lateral collaboration

agreements to share regulatory practices. It remains to

be seen whether such collaborations will facilitate review

and thus reduce the overall time to realizing any

particular SMR/MMR concept. We further note that global

institutions, such as the IAEA, WNA, OECD-NEA, WANO

| Figure 4

Conceptual sketch of weighting factor assignment.

and related promote common understanding – here with

respect to safety-in-design of SMRs/MMRs and other

advanced reactor concepts. The authors herein describe

emerging drivers or influences, based on many lessons

learned in reactor concepts and designs. We offer this

account since, design methods and approaches often

remain proprietary and as such, not openly discussed. We

thus offer for contemplation and discussion, high-level

aspects of safety-in-design of SMRs.

Figure 4 first shows a qualitative “high, medium or

low” weighting in importance versus the INSAG-10 levels

(1 to 5), meant to reflect historial perspective on defencein-

depth. The figure compares conventional reactors

( larger plants) versus SMRs currently proposed. We note

that the weigthing for convential reactors may sensibly

decrease incremental manner if level “1, 4, 5”, for example,

loosely correspond to AOOs, DBA an BDBA respectively.

That is, convential reactors have largely been designed so

that safety systems can respond to and counter consequences

of the postulated DBA. However, history has

taught us that human operational error can generate

BDBA-type situations; that is, leading to core meltdown

(degradation) and (unintended) release of radioactivity

beyond the plant boundary. Thus, for older generation

reactor designs (Generation II), one could imagine a

higher weighting for levels 1-to-3, relative to levels 4-to-5

event. Since, the authors anticipate arguments under such

qualitative perspectives, an uniform, medium weighting

across levels, 1-to-5, is also shown. It is conceivable that a

particular, recent design (Generation III, III+) could

feature uniform weighting as depicted.

In contrast, the designs of current SMRs are generally

expected to reflect generational improvements in safety- indesign,

overall. Thus, at minimum, the SMR may feature

inherent, passive safety system/s in its design, and thus

reflect a safety-in-design philosophy, that may emphasize

at least “M” weighting for unlikely, level “4 or 5” scenarios.

In so doing, the design eliminates the need for immediate

(human) emergency response. This latter philosophy may

not always be apparent by studying the design itself, but

depicted through an integration of a number of safety- indesign

aspects. In reality and with operational excellence

taken into consideration, the relationship may be

something similar to the (non-linear) dotted trend with

high imporance placed on both low and higher level

scenarios. Any difference in magnitude or slope comparing

conventional reactors to SMRs, thus reflects historical



Small Modular Reactor Safety-in-Design and Perspectives ı Akira Tokuhiro, Chireuding Zeliang and Yi Mi

atw Vol. 66 (2021) | Issue 3 ı May




SMR target

frequency (/yr)*

No. Generic eliminated scenarios Contributing innovative features

1. Large Break Loss of Coolant Accidents (LB-LOCAs) Integrated Reactor Cooling System

2. Elimination of control rod ejection/injection accidents Integrated Control Rod Drive Mechanisms (CRDMs)

3. Exclusion of inadvertent reactivity insertion as a result of boron dilution Eliminated liquid boron reactivity control system

4. Elimination of loss of flow accidents and failures/scenarios related to

reactor coolant pumps

Naturally circulated primary system

5. Elimination of the need for external power under accident conditions Fail-safe passive safety features on loss of power

| Table 2

SMR design features that challenge conventional safety analysis.

Design characteristics

Integral reactor coolant system (RCS)-

design-reduced accident initiators


Level 1 < 10 -2 Initiating event frequency

Level 2 < 10 -5 Failure detection capability and control action

(automatic or manual)

Level 3 < 10 -8 Core damage frequency (CDF)

Facilitating factors in (SMR) passive safety systems (PSSs) start-up/operation

Minimizes accident initiators, thus consider use of PSS.

Results in a simplified design

Lower core power capacity Less (magnitude) decay heat to be removed 30)



Level 1

Level 4 < 10 -10 Conditional containment failure probability Level 2

Level 5 < 10 -12 Large early release frequency (LERF) Level 3

| Table 1

Relationship among DiD, PRA, existing requirements and expectations. *small values can be argued, conservatively

Current regulatory

requirements (/yr)

< 1 x 10 -5 and < 1 x 10 -4

(depending on regulator)

< 0.1

(depending on regulator)

< 1 x 10 -6

(depending on regulator)

Larger surface to volume ratio

Larger primary coolant inventory

per MW(th)

Smaller reactor core power density

Large secondary coolant inventory,

e.g., NuScale reactor pool

Taller and broader reactor pressure

vessel or vessel containing core

Facilitates decay heat removal due to large surface area,

particularly for single phase flow

Larger heat sink for natural circulation; larger buoyancy-driven

flows/regioins; reduces requirements for heat removal systems 31)

Larger thermal-hydraulics margins; favourable in long term decay

heat removal, in particular via PSSs

Facilitates passive decay heat removal and

containment cooling 10)

Facilitates decay heat removal via natural circulation,

i.e., higher elevation difference between heat source and sink 30)

| Table 3

SMR design features that challenge conventional safety analysis.

lessons learned and competing philosophies in safety- indesign

of nuclear reactors.

Continuing, Table1 below provides a semi-quantitative

equivalent to Figure 4 but compares INSAG-10 levels,

against the possible SMR target frequencies (a design

merit), short descriptors of the corresponding attributes of

an event or accident, the commonly noted PRA levels, and

the currently known regulatory values for existing plants.

This table is qualitative and simply contrasts different

perspectives that may be used by a SMR designer. We

recognize that small frequency values, say less than 1E-08,

may not hold regulatory meaning and as such, higher

frequencies for levels 1-5 may apply, depending on the

practicality of such values in regulatory review of

submitted SMR/MMR designs and concepts. Finally, as a

measure of confidence in its design, a vendor may assume

a probability 3 orders of magnitude smaller at each level,

except at level 4-and-5.

Table 2 provides five representative, generic events

for which design features and/or design concepts of

recent SMRs (also MMRs), have either greately reduced or

eliminated all together the likelihood of such vulnerabilities,

most often associated with conventional reactor

designs. Here again, through gradual advancements in

conventional reactor safety-in-design, further facilated by

ongoing development in SMRs, safety-in-design and

defence- in-depth have both been embodied in various

SMR designs. The rightmost column gives an example of

the SMR design feature that eliminated the generic


Finally, Table 3 representative design characteristics

or features observed in recent iPWR-type SMRs (left

column), relative to their phenomenolgical impact in

assuring energy removal under many severe accident

scenarios and design vulnerabilties associated with

conventionl reactor designs. Further, for a given SMR design

encompassing a mulitple number of design characteristics

as above, operator intervention is greatly reduced or eliminated

for substantial durations of time, starting from the

initiating event and possibly linked to an additional

sequence of unlikely events. In other words, current SMR

designs anticipate BDBA and catastrophic, external events.


Small Modular Reactor Safety-in-Design and Perspectives ı Akira Tokuhiro, Chireuding Zeliang and Yi Mi

atw Vol. 66 (2021) | Issue 3 ı May

5 Uphill costs and getting to the end

It is no secret there are major milestones on the path to

realizing any new commercial nuclear power plant. Some

major milestones that come to mind are first criticality and

connection to the electricity grid. New conventional builds

have however become too expensive, relative to other

large infrastructure projects and public spending that

address regional to national priorities. As ramification of

the Fukushima Daiichi earthquake-tsunami-nuclear plant

accident, and examples of cost overruns and delays associated

with large nuclear plant projects persist, “opportunist”

have taken sides – to either support or not support

nuclear energy as a valued energy source option. It is well

known that the merits of nuclear power (as zero to low

carbon) in addressing the negative impacts of climate

change, continue to be argued in public and social media

spaces. Pragmatism regarding public infrastructure need

can become easily mired and disconnected to those elected

and engaged in media. If the authors may inject opinion,

nuclear energy is an energy technology that we have today

and it provides, at minimum, the time needed for society to

reach consensus via change in mindsets, values and beliefs.

This lead author is of the opinion that addressing climate

change is just as much a matter of change needed in how

we live and consume. Energy consumption and its sources

are very much part of the anthropocene.

While various perspective on developments in SMRs/

MMRs can be taken, the authors’ position here is that

getting to the “end” may be the most important.

6 Conclusion

Development of various Small- and Micro-Modular

Reactor concepts, regardless of its point of origin depends

on alignment of both timely and prudent engineering and

design efforts, sustained financial backing during this

effort and, public and/or private stakeholder investments

so that a first-of-a-kind reactor (FOAK) is constructed on

time and at cost, post timely regulatory safety-in-design

approval. Beyond the FOAK plant, expectations are such

that sustained investments and commitments, parallel

reduction in cost with each additional unit constructed in

modular manner.

Here the authors have elaborated on a holistic safety- indesign

perspectives wherein technical features make

design and beyond design basis accidents nearly impossible

(or eliminated), and even under improbable initiating

events, decay heat removal is passive such that it does not

require operator intervention for a defined length of time.

The article also emphasized that completion of the design

and (time) efficient regulatory review of the submitted

design, are of tantamount importance with respect to the

sustained investments, and can determine the fate of any

given SMR/MMR design. It is clear that regional to national

support of nuclear energy, an existing history of reactor

design development, a skilled nuclear and energy sector

workforce, and an existing supply chain are increasingly

expected conditions when considering new nuclear plants.

Finally, early public engagement and confirmation of

gradual public acceptance and social license (nominal

acceptance of nuclear energy) must exist, as identified via

fleeting social media platforms. This is the reality of the

world that we live in today. Let us brave the future of

nuclear energy.


The lead author thanks Ontario Tech University and its

Faculty of Energy Systems and Nuclear Science. He also

thanks contributions to recent research on SMRs from

Chireuding Zeliang and Yi Mi. The lead author would

like to thank partial support by the National Science,

Engineering Research Council (of Canada), CREATE

528176-2019, awarded to McMaster University with

Ontario Tech University as partnering institution.


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expectations, prospects and impediments of their deployment”, Progress in Nuclear Energy 79,

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Reactor Developmental Status, Design Characteristics and Passive Features: A Review. Energies

(Basel), 13(11), 2898–. https://doi.org/10.3390/en13112898

[33] IAEA –International Atomic Energy Agency, Advances in Small Modular Reactor Technology

Developments (2020).

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metrics into new reactor designs. Nuclear Engineering and Design, 330(C), 157–165.

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atw Vol. 66 (2021) | Issue 3 ı May


[36] Zohuri, B.. Small Modular Reactors as Renewable Energy Sources . Cham, Switzerland: Springer,

2019. Print.

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[43] Wikipedia article on “sodium-cooled fast reactor, as of April 10, 2021;


[44] Wikipedia article on “Experimental breeder reactor II”, as of April 10, 2021;



Prof. Akira Tokuhiro

Dean and Professor at the Faculty

of Energy Systems and Nuclear Science

Ontario Tech University, Ontario, Canada


Akira Tokuhiro is Dean and Professor at the Faculty of Energy Systems and Nuclear

Science at Ontario Tech University in Oshawa, Ontario, Canada. His primary R&D

interests are in development of advanced reactor concepts, including small modular

reactors. He joined Ontario Tech University from NuScale Power. He has nuclear and

energy R&D experiences in Switzerland, Japan, USA and Canada.

Yi Mi

Master of Applied Science in Nuclear Engineering


Yi Mi is a young nuclear engineering professional with research experience in

Probabilistic Risk Assessment (PRA) and Small Modular Reactor (SMR) Technology

Development. He completed his Master of Applied Science degree in January 2020,

in Nuclear Engineering, at Ontario Tech University His research was on SMRs,

especially integral Pressurized Water Reactors (iPWRs). His focus was on safetyin-design

methodology of small modular reactors (SMR). Specifically, he was

integrating a number of tools and methods such as, system analysis and

probabilistic risk analysis codes (LabVIEW and CAFTA), but including in the

methodology, scaling analysis of iPWR type SMR with passive safety systems.

Also, he studied the similarity and differences among different types of SMRs

including iPWR, Steam Cycle-High Temperature Gas-Cooler Reactor (SC-HTGR),

Fluoride-salt-cooled High Temperature reactor (FHR) and CO2-cooled micro modular

reactor (MMR). Before OntarioTech, hec ompleted a Bachelor of Engineering in

Chemical Engineering in Sichuan University.

Chireuding Zeliang

Junior Engineer/Analyst

Kinectrics Inc., Toronto, Canada

Chireuding Zeliang is a young nuclear engineering professional with research and

work experience in Probabilistic Risk Assessment (PRA) and Small Modular Reactor

(SMR) Technology Development. He currently works with Kinectrics Inc. as a Junior

Engineer/Analyst in the areas of PRA as well as Design Modification of Safety and

Supporting systems in CANDU nuclear plants. Prior to joining Kinectrics, Chireuding

pursued his research career in PRA and SMR Technology Development from University

of Ontario Institute of Technology under a 15 countries collaborative IAEA Coordinated

Research Project on ‘Design and Performance Assessment of Passive Engineered

Safety Features in Advanced SMRs’. He holds two (2) Master’s degree from

University of Ontario Institute of Technology and Indian Institute of Technology

Kanpur, and a Bachelor’s degree from North Eastern Regional Institute of Science

and Technology, India.


Small Modular Reactor Safety-in-Design and Perspectives ı Akira Tokuhiro, Chireuding Zeliang and Yi Mi

atw Vol. 66 (2021) | Issue 3 ı May

Did you know?

Nuclear Power as Part of Sustainable Energy Policy –

UNECE Working Group Report

In the 2021 report “Application of the United Nations Framework

Classification for Resources and the United Nations Resource

Management System: Use of Nuclear Fuel Resources for Sustainable

Development Entry Pathways” prepared by the Expert

Group on Resource Management (EGRM) of the United Nations

Economic Commission for Europe (UNECE) the role of nuclear

energy is explored in the framework of the UN‘s 2030 Agenda

for Sustainable Development. Key insights of this work among

other are:

p “Nuclear energy is an indispensable tool for achieving the

global sustainable development agenda. It has a crucial role

in decarbonizing the energy sector, as well as eliminating

poverty, achieving zero hunger, providing clean water,

affordable energy, economic growth, and industry innovation.


p “Nuclear energy entry pathways for newcomer countries align

with the 2030 Agenda for Sustainable Development. Nuclear

energy programmes, based on the IAEA‘s Milestones

Approach, support national energy needs, socio-economic,

and environmental goals, and can help countries meet international

climate commitments”

p “Currently available nuclear reactor designs are based on

mature and proven technologies that in some instances have

been licensed to operate for 80 years. ... They provide reliable,

affordable and low-carbon electricity that will support a

country in meeting its sustainable development goals.”

The report states to meet “a need expressed by global decision

makers to better understand the role nuclear energy may play in

the energy transition”. It gives advice on how to foster and embed

the entry into nuclear energy in a larger framework of policies

and recommendations on how to facilitate the implementation of

a nuclear energy programme. The “embedding” policies include

policies for sustainable development and a low-carbon energy

transition, energy market reforms that support long term strategic

investment, policies to improve energy security and resilience

and an industrial development strategy. Typical policies aiming

for a low carbon energy system that foster nuclear power are

deep decarbonization or a net-zero carbon target, technologyneutral

low-carbon energy portfolio standards, coal/fossil fuel

phase- outs, increasing electrification of heat and transport,

decarbonization and modernization of energy-intensive industries.

Regarding the electricity market design the report calls

among other to value energy reliability, resilience and the need

for technologies providing secure, reliable and dispatchable

generation to support the integration of variable renewables. It

proposes as well to include non-power (socio-economic) benefits.

The report makes mention of the assessment in a recent OECD-

NEA report that for a generalized country the most cost-effective

option to achieve a decarbonization target of 50 g CO 2 /kWh is a

mix relying primarily on nuclear energy. Even in cases with ultralow-cost

wind and solar PV an aggressive decarbonization target

would require a share of 40 – 60 percent dispatchable low-carbon

technologies such as nuclear.

When eventually a decision in favour of nuclear power has been

reached, supporting measures for implementation according to

the report are international cooperation, regulatory harmonization,

the development of indigenous capabilities, the delivery of

projects on time and on budget, the proactive engagement of

stakeholders and diversity in the nuclear sector with regard to

gender balance. The report also assesses the issues of sustainable

resource management, socioeconomic and environmental

factors, the nuclear fuel cycle, nuclear waste management

and disposal as well as nuclear technologies and innovation

perspectives among other.






Projected Costs of Energy Technologies by

Country (2020) in USD/MWh (Median LCOE)

(Data: IEA)

External Costs of Health effects for

14 Technologies as of 2025,

NEEDS study 2009


Lignite post-comb CCS

Lignite oxy-fuel CCS


Coal post-comb CCS

Coal oxy-fuel CCS


in Euro cent/kWh


Application of the United

Nations Framework

Classification for

Resources and the

United Nations Resource

Management System:

Use of Nuclear Fuel

Resources for Sustainable

Development – Entry

Pathways, Expert

Group on Resource

Management (EGRM),

United Nations Economic

Commission for Europe

(UNECE), Geneva 2021




India United States China Europe Japan

Coal Gas


Nuclear Onshore


(> = 1MW)



Solar PV

(utility scale)



Solar Thermal




0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

For further details

please contact:

Nicolas Wendler


Robert-Koch-Platz 4

10115 Berlin


E-mail: presse@



Did you know?

atw Vol. 66 (2021) | Issue 3 ı May


The Nuclear Innovation Policy of Canada


Q&A with the Ministry of Natural Resources Canada

Canada pursues an ambitious climate policy and is strongly committed to nuclear innovation. Today Canada is a

front runner in the development, design review and licensing of micro, small modular and advanced modular reactors.

Natural Resources Canada (NRCan) supported this development with Canada’s SMR Roadmap process in 2018 and the

SMR Action Plan which is expected to yield concrete results within this decade. Canadian nuclear innovation policy

aims beyond decarbonization in Canada and the fulfillment of specific Canadian local energy needs. Part of the policy

is to establish new nuclear technologies globally as part of climate solutions and become a prime supplier of such

technologies. The Q&A below with the Ministry of Natural Resources Canada (NRCan) gives you insights on the

Canadian nuclear policy, its consensual making, its goals and the current state of progress.

About the SMR Action Plan

Canada's Small Modular Reactor (SMR) Action Plan is

Canada's plan for the development, demonstration and

deployment of SMRs for multiple applications at home and


SMRs are a promising new technology that could unlock a

range of benefits: economic, geopolitical, social, and

environmental. Canada’s SMR Action Plan brings together

essential enabling partners, leveraging their strengths to

lock-in these benefits and lead the world on SMRs.

The Action Plan is the result of a pan-Canadian effort

bringing together key enablers from across Canada, which

are called “Team Canada” – the federal government,

provinces and territories, Indigenous Peoples and communities,

power utilities, industry, innovators, laboratories,

academia, and civil society.

Each of these key enablers has contributed a chapter to the

Action Plan, describing a concrete set of actions they

are taking to seize the SMR opportunity for Canada.

Collectively, these chapters demonstrate the breadth of

engagement on SMRs across the country and outline the

depth of progress and ongoing efforts.

Canada has a long and impressive tradition in the

use of nuclear energy and nuclear technologies.

The CANDU reactors have been successfully

developed and introduced; the only commercial

non-LWR technology with worldwide recognition.

From your point of view, what are the Canadian´s

Government expectations for the nuclear sector?

Small modular reactors (SMRs) are a potential gamechanging

technology that can help Canada meet and

exceed its emissions targets while creating economic

opportunities in a post-pandemic world.

Nuclear energy plays an important role in Canada’s

current energy mix, accounting for 15 percent of our

electricity supply, including approximately 60 percent of

our supply in Ontario and approximately 40 percent in

New Brunswick. The sector also contributes approximately

$17 billion a year to Canada’s gross domestic product, and

accounts for approximately 76,000 jobs across the country,

including over 200 small- and medium-sized enterprises.

SMRs are an opportunity for Canada to produce nonemitting

power where it’s needed. The Government of

Canada recognizes that it has a role to play in supporting

this emerging innovative sub-sector, and in enabling

Canada to seize these benefits.

With the “SMR Road Map” and the recent “SMR

Action Plan” from December 2020 Canada places

itself on the forefront of this technology. What are

the primary objectives of this SMR policy?

SMRs have the potential to support Canada in its

goals to reach net-zero by 2050 by accelerating electricity

decarbonization, moving Canadians off coal and diesel,

and driving deep indus trial decarbonization, all while

creating jobs for Canadians.

Over 100 organizations have submitted chapters to

the Action Plan. For more information on our SMR

Roadmap and Action Plan, see the ‘About’ section here:


What are the main advantages and prospective

applications of this technology?

SMRs are nuclear reactors that are:

p smaller, with a lower up-front capital investment than

traditional nuclear power plants;

p simpler, involving modular designs and a fleet-based

approach to control cost and shorten project schedules;


p cheaper to compete with alternatives, enabling new

applications such as hybrid nuclear-renewable energy


Many SMR designs also offer enhancements to improve

safety, performance, and prevention of accidents.

In Canada, SMRs have three major areas of application:

p on-grid power generation, especially in provinces

phasing out coal in the near future. Utilities want to

replace end-of-life coal plants with non-emitting baseload

plants of similar size;

p on- and off-grid combined heat and power for heavy

industry, such as cement producers; and

p off-grid power, district heating, and desalination in

remote communities. These currently rely almost

exclusively on diesel fuel, which has various limi tations.


The Nuclear Innovation Policy of Canada ı Ministry of Natural Resources Canada

atw Vol. 66 (2021) | Issue 3 ı May

The “SMR Action Plan” assembles an impressively

broad coalition of stakeholders from many

segments of society. How was it possible to gain

so much and diverse support for the Canadian

SMR endeavor?

Natural Resources Canada ( NRCan) recognizes the

potential for this emerging area of nuclear innovation and

understands the importance of diverse, strategic partnerships.

That’s why, in 2018, NRCan convened Canada’s SMR

Roadmap, a ten-month cross- country conversation on

Canada’s SMR opportunity that brought together

provincial and territorial governments, power utilities,

industry and other interested stakeholders to chart a path

forward for this technology in Canada. The report made

over 50 recommendations, which Canada’s SMR Action

Plan responds to and builds on.

The SMR Action Plan is the result of a pan-Canadian

effort bringing together key enablers from across Canada,

including the federal government, provinces and territories,

Indigenous Peoples and communities, power utilities,

industry, innovators, laboratories, academia, and civil

society. Each of these key enablers contributed a chapter to

the Action Plan, describing a concrete set of actions they

are taking to seize the SMR opportunity for Canada.

Collectively, these chapters demonstrate the breadth of

engagement on SMRs across the country and outline the

depth of progress and ongoing efforts.


Decarbonization is a global challenge, not a

challenge for single countries or regions. Is the

export and the sharing of know-how of Canadian

nuclear technology to other countries part of the

“SMR Action Plan”?

The SMR Action Plan is Canada’s plan for the development,

demonstration and deployment of SMRs for multiple

applications at home and abroad. Over the past six

decades, the Government of Canada has successfully

established and maintained strategic bilateral and multilateral

partnerships around the globe to advance shared

nuclear energy priorities. With our own power reactor

technology and full-spectrum nuclear capabilities, Canada

belongs to an elite group of Tier 1 nuclear nations.

With demonstrated leadership and expertise in nuclear

science and technology, Canada is in a position to lead

and contribute to international partnerships to support

the development and deployment of SMRs across the


What is the timeline of SMR projects in Canada and

which are the closest to realization?

The Government of Canada understands the important

role it has to play in advancing SMR technology in time for

Canada to be a world leader and to provide a non-emitting

alternative for jurisdictions that must phase out conventional

coal-fired power plants by 2030. The Government of

Canada also recognizes the leadership of provincial and

territorial governments and power utilities in SMR deployment,

and plans to continue working together to make

Canada a world leader in SMR technology.

Several provinces that must phase out conventional

coal-fired power plants are at a critical decision point for

new electricity sources, and the commercialization of

SMRs could allow these provinces to achieve and lock in a

decarbonized energy mix.

The ongoing projects in Ontario to extend the life of the

Darlington and Bruce nuclear plants have led to a rampedup

nuclear supply chain, creating thousands of new jobs.

| This map shows that all uranium comes from mines in Saskatchewan, but uranium processing,

refining, conversion, fuel fabrication, research and waste management happens across Canada. Nuclear

power stations are located in Ontario and New Brunswick. (Source: Natural Resources Canada)

As these projects end in the late 2020s and early 2030s,

SMR projects could present an opportunity to sustain this

capacity into the long term, as found through Canada’s

SMR Roadmap. In other regions throughout the country,

including Atlantic, Western and Northern Canada, SMRs

are an opportunity to develop a new economic driver

supporting good, middle-class jobs, and the Government

of Canada supports efforts to enable all regions to benefit

from Canada’s SMR oppor tunity.

Through Canada’s SMR Action Plan, SaskPower identified

that they are evaluating several potential low

emissions pathways, including the deployment of nuclear

power from SMRs in the 2032 – 2042 timeframe, with a

view to limiting the deployment of new natural gas

generation in the 2025 – 2040 timeframe.

We are putting significant effort into building a strong

foundation so that we are ready to unleash the full

potential of SMRs, and projects in Canada are currently

proceeding through three streams:

p Stream 1 refers to near-term, grid-scale SMRs. Ontario

Power Generation has announced that it is working

towards a new grid-size SMR at its Darlington Nuclear

Station by about 2028.

p Stream 2 refers to the development of two advanced

Generation IV SMR designs. This is being led by New

Brunswick, and NB Power envisions technology

demonstration at the Point Lepreau site in the early to


p Stream 3 refers to a new class of micro SMRs, with

potential to replace the use of diesel for remote communities

and mines. Canadian Nuclear Laboratories (CNL)

launched an Invitation for Demonstration in 2018, to

invite SMR vendors to propose demonstration projects

for siting at an AECL-owned, CNL-managed site.


The Nuclear Innovation Policy of Canada ı Ministry of Natural Resources Canada

atw Vol. 66 (2021) | Issue 3 ı May


| Figure 1

Electricity generation by source, Canada 1990-2019. (Source: www.iea.org/countries/canada)

| Figure 2

Nuclear electricity generation, Canada 1990-2019. (Source: www.iea.org/countries/canada)

At least, an adopted regulatory framework is

necessary for SMRs. Until now, which milestones

have been achieved and is there any international

cooperation between governments and institutions

on the subject?

Canada has a world-renowned regulator committed to

safety and open to innovation, as well as a comprehensive

plan to manage nuclear waste in the long-term. This

combination of enabling elements, coupled with our

commitment to nuclear excellence, means Canada is

poised to lead the world.

The Canadian Nuclear Safety Commission (CNSC)

offers optional pre- licensing engagement with potential

applicants, as well as a pre-licensing vendor design review

service, to help identify any significant barriers to licensing

SMR technologies in Canada and thereby minimize potential

impediments during the licensing process. 12 SMR

design vendors are currently engaged with the CNSC in

the vendor design process and are at various stages of


On international collaboration:

In 2019, the CNSC signed a memorandum of cooperation

with the United States Nuclear Regulatory Commission

that could support more efficient reviews of SMRs.

The CNSC and the United Kingdom (UK) Office for

Nuclear Regulation (ONR) recently (Oct 2020) signed two

agreements to explore further collaboration and to more

effectively regulate an ever-changing nuclear sector.

A cornerstone of SMR technology to reach broad

distribution as energy technology is serialization

and the expected cost degression by number of

installations. Are there already specific plans to

realize this?

Canada’s SMR Roadmap recognizes that as the technology

matures, the cost of individual units will decrease. The

Roadmap identifies several factors that will determine

how quickly these costs decline, such as:

p how many SMRs are built;

p construction experience; and

p the degree of standardization within SMR fleets.

A major topic in discussions about nuclear power is

waste management. What is the state of affairs in

Canada particularly with regard to final disposal?

The health, safety, and security of Canadians and the

environment is the government’s top priority when it

comes to regulating nuclear energy and materials. The

Government of Canada is committed to ensuring that safe

solutions are in place for managing radioactive waste now

and into the future.

Currently, all radioactive waste in Canada is safely

managed in facilities licensed by the Canadian Nuclear

Safety Commission (CNSC) – Canada’s independent

nuclear regulator.

The Nuclear Waste Management Organization

( NWMO) is responsible for implementing Canada’s plan

for the safe, long-term management of used nuclear fuel –

including that created using new or emerging technologies.

The Government of Canada is committed to continuous

improvement with respect to ensuring that safe solutions

are in place for managing radioactive waste. For this

reason, Canada launched an open and transparent engagement

process to modernize Canada’s radioactive waste

policy. Between now and fall 2021, the Government of

Canada is conducting a review of Canada’s Radioactive

Waste Policy. As part of this process, officials are engaging

with stakeholders and talking to Canadians, including

Indigenous peoples, to ensure all voices are heard.

What are the differences for waste management

between existing nuclear power plants and the

smaller scaled SMR based nuclear power plants?

Will the SMR path require changes to the waste

management strategy or will it be part of existing


All radioactive waste in Canada is being safely managed

according to international standards at facilities that are

licensed and monitored by the CNSC. Depending on the

waste type and other characteristics, owners of waste from

SMR technologies may be able to use existing concepts or

may need to implement new solutions for their radioactive



Nicolas Wendler

Head of Media Relations and Political Affairs

KernD (Kerntechnik Deutschland e.V.)



The Nuclear Innovation Policy of Canada ı Ministry of Natural Resources Canada

atw Vol. 66 (2021) | Issue 3 ı May

“I am Personally Very Excited About

Canadas’s Positioning as a Tier One

Nuclear Power and also as a First Mover

in Small Modular Reactors“

Interview with John Gorman ı President & CEO of Canadian Nuclear Association


The Canadian Nuclear Association represents an

established nuclear industry which has decades of

experience with nuclear technology. Can you give

us a short overview of the nuclear sector in Canada?

Let me start by saying that Canada is in a quite unique

situation in terms of having both a vibrant nuclear ecosystem

that is being fueled by the refurbishments of

existing plants in our largest province of Ontario and in

turn that is being used as a platform to do all sorts of

innovation in Small Modular Reactors but also in other

areas like medical isotopes. So, the combination of these

two things, the healthy nuclear ecosystem and the

innovation that we have going on in Small Modular

Reactors is positioning Canada to provide climate change

Small Modular

Reactors will help us

continue that track

record and help others.

solutions, the decarbonization

of very important

sectors of our economy

here in Canada and by

extension the ability to be

a first mover in helping

other nations around the

world lower their GHGs. So, I am personally very excited

about Canadas’s positioning as a tier one nuclear power

and also as a first mover in Small Modular Reactors.

In terms of actual statistics, we are a tier one nation

being in this business for more than sixty years, with a very

respected regulator and a highly respected track record in

terms of the efficient and safe operation

of nuclear plants. We currently

have 12 different SMR technologies

being evaluated and going through

the review and licensing process in

Canada making us a world leader in

terms of the number of technologies

and the speed with which we are developing them. CANDU

technology is deployed in seven countries around the

world and is still very actively involved in existing markets

and developing markets. A great example of that is

Romania, where they are very likely going to refurbish

John Gorman

Retiring coal in Ontario

became and still is north

Americas single largest

carbon reduction initiative.

President & CEO of Canadian Nuclear Association

John Gorman is President & CEO of Canadian Nuclear Association, past President

& CEO of the Canadian Solar Industries Association (CanSIA) and a Director on the

board of the Energy Council of Canada (ECC). John served as Canada’s Designate

to the International Energy Agency’s Executive Committee (PVPS) and was a

Founder of the Canadian Council on Renewable Electricity (CanCORE). He’s using

this experience to secure a leading role for nuclear energy at the heart of Canada’s

energy transition. Before joining CanSIA, he was the Senior Vice President of

Empower Energies, an innovative, global integrator of energy systems. He has

served as a director on the boards of numerous community and corporate

organizations, including one of the nation’s largest electric utilities. John has been

recognized as one of Canada’s CLEAN50 and is the recipient of the “40 Under 40”

business award for excellence in business practices. He was awarded the

designation of Climate Project Ambassador by Nobel Laureate Al Gore in 2008.

their two existing CANDU units and complete the

construction of two additional units. So, Canada while

being a smaller nation is a world leader in nuclear and we

have accomplished some amazing things here from a

climate perspective which I am eager to talk to you about

and Small Modular Reactors will help us continue that

track record and help others.

You already mentioned the refurbishment programs.

As I know of this is a quite unique feature,

partially after long term shut downs. To understand

this process, what determined the decisions about

the refurbishment in both cases, i.e., the shut

downs earlier and then the refurbishments and

long-term operation later?

This is an amazing story, that I hardly ever get asked about,

so I am pleased to talk about it. Let me start with the punch

line. Ontario, the largest province in Canada decided in the

early 2000s to phase out all of our coal fired electricity.

When we did that, coal fired electricity was providing

about 25 % of Ontarios electricity, it was creating smog

days and health problems and obviously

emitting a lot of emissions. We replaced

89 % of that coal fired electricity by

bringing back online two units that had

been shut down. So, in the process we

were able to retire coal very quickly and

retiring coal in Ontario became and still is

north Americas single largest carbon reduction initiative.

That’s the punch line. More specifically in 1997 Ontario

Hydro, the utility, and the government made the decision

to shut down two of our units because there was no

demand for this electricity, there was a surplus. But by the


“I am Personally Very Excited About Canadas’s Positioning as a Tier One Nuclear Power and also as a First Mover in Small Modular Reactors“ ı John Gorman

atw Vol. 66 (2021) | Issue 3 ı May


early 2000s supply had become tight, we needed more

electricity and at the same time we made the decision to

phase out coal fired electricity. We addressed both of those

issues by restarting four units and subsequently made the

decision to refurbish a number of our units. We are likely

going to close down two of them in the mid-2020s but we

will continue to operate the majority of the 18 units in

Ontario. So, this is the story: surplus of generation in 1997

made the decision for shut downs, then as more generation

was needed and the phase out of coal was decided we

brought them back on and we undertook this refurbishment.

At this moment the refurbishment is the single

largest infrastructure project in Canada. It is a 26-billiondollar

refurbishment that is taking place over ten years

and it is employing a lot of people and driving a lot of


This brings me to a follow-up question: when I

remember the discussions, we had in Germany

about longer operation of nuclear power plants in

2009 and 2010 there was a fierce opposition of the

green party and of environmental organizations.

Were there discussions of that kind and organizations

parties or movements opposed to the

refurbishment of nuclear power plants in Canada?

There are certainly detractors of nuclear power in Canada.

We continue as an industry globally and in Canada to be

exposed to that sort of stigma and misinformation and not

fact-based attitudes towards nuclear. But at the end of the

day Canada has an outstanding record in terms of the safe

operation and managements of its fleet. Canadians

recognize that we are a world leader

in nuclear power and clearly in the

end the arguments and support in

favor of refurbishment outweighed

the detractors. Our country is very

large, there are ten different provinces

which are responsible for their own electricity supply so it

becomes a very regional discussion rather than a national

discussion. This might be a key difference between Canada

and Germany. There is one thing that we know for certain:

the more people know about nuclear the more supportive

they are. In the provinces where we do have nuclear power

like New Brunswick or Ontario or in Saskatchewan where

there are uranium operations, these regions are very comfortable

with nuclear or at least much more supportive

than other provinces.

Nuclear technology is not just about nuclear power

plants, there are also very important other sectors.

One of them is isotope production for many

purposes including medical ones. In 2018 a major

production facility in Canada that was important

globally, the NRU reactor, was taken out of production

and important capacity was lost. How was

it compensated for or was it compensated for?

It has been compensated for in a very interesting way.

Firstly, the NRU had to be taken down because it served its

lifespan. But we continue to have radioisotope production

in our existing conventional power reactors and in other

research reactors as well as particle accelerators such as

TRIUMF and Canadian Light Source

in western Canada. Despite the end of

operation of NRU, we still have other

research reactors and particle accelerators

that are fulfilling that need.

However, it has also spurred real

The more people know

about nuclear the more

supportive they are.

innovation here in Canada using our existing CANDU

reactors. So, what we are seeing is that our two largest

operators, Bruce Power and Ontario Power Generation

have partnered with companies in the private sectors such

as BWXT and isoGEN to produce isotopes from conventional

reactors. This is really fascinating. There is no need

to interrupt the operation of the units in any way. Ontario

Power Generation and BWXT are beginning to produce

Molybdeneum-99 at the Darlington Nuclear Association

and Bruce Power, BWXT and Isogen similarly are beginning

to produce Lutetium-177 for cancer therapy. At the

same time, we continue to produce a large portion of the

worlds supply of isotopes through our other assets. This

includes more than 70 per cent of the global supply of

Cobalt-60 and about 60 per cent of the world market for

Iodine-129 is produced here as well. We have adapted and

used innovation to replace the isotope production that was

shut down.

Let’s get back to power, the major question for

many countries nowadays given all the climate

discussions and climate targets. What is the longterm

perspective for nuclear power in Canada and

how is it included in Canadian or provincial energy

and climate strategies?

The long-term perspective for nuclear power in Canada is

extremely bright for the reasons we have already spoken

about. The refurbishment of our CANDU power plants in

Ontario is the largest infrastructure program in Canada. It

is going to keep those plants operating well into the 2060s

and they are providing 15 per cent of Canadas clean

electricity and a healthy nuclear ecosystem

that is the foundation for other work that we

are doing in Small Modular Reactors and

isotopes. With this very strong foundation of

the refurbishments going on with a large work

force and innovation we have become a first

mover in Small Modular Reactors. The government has

started funding a number of the SMR-technologies that are

under review and licensing and we expect to see more

funding announcements in a short number of weeks

coming. We also have an extraordinary level of coordination

between government and industry and the provinces

in the development and deployment of Small Modular

Reactors. And this is quite exceptional and exciting: four of

our provinces have signed a Memorandum of Understanding

on the development and deployment of SMR. The

federal government has come out and identified nuclear as

being needed and essential for net zero in 2050, our

national goal. So, we have both the federal government

identifying nuclear as being essential to reaching net zero

2050 and four provinces and their utilities who have

agreed on a business plan for the development and deployment

of SMR in their regions. When you combine this with

our very progressive regulator, the Canadian Nuclear

Safety Commission, which is very well suited to evaluate

and work with innovative technologies much more so than

some of the very prescriptive regulators we see in other

places, it really becomes a competitive advantage for us.

In fact, when you look at Canadas commitment around

climate change which is very aggressive with the objective

The federal government has come

out and identified nuclear as being

needed and essential for net zero

in 2050, our national goal.

of net zero in 2050 where

nuclear is acknowledged as a

key element of that energy

plan and we have both a long

term set of operating assets

producing 15 per cent of our


“I am Personally Very Excited About Canadas’s Positioning as a Tier One Nuclear Power and also as a First Mover in Small Modular Reactors“ ı John Gorman

atw Vol. 66 (2021) | Issue 3 ı May



electricity and a world leading advantage on the development

of SMR, so the long-term perspectives of nuclear in

Canada are assured.

To realize the opportunities that exist with SMRs

regulatory issues are quite important. They need

certain adaptations compared to larger units and

apparently this is working well in Canada as I can

conclude from what you said. But is there also work

going on to achieve some standardized regulations

on SMR designs that are in the pipeline, are you

cooperating with the US and the UK and maybe at

some point with the European Union too because

there probably soon will be an international market

for this type of plants.

You identified one of the most important issues here.

Globally, to realize the benefits of SMR will need some

standardization in terms of regulation. As you know this is

a departure from a long history of nuclear power being a

very nationally driven sector. Each country focused on a

particular type of technology and set up a regulatory

framework for this technology. Canada is a good example

for this with its CANDU- technology. Of course, SMR

depend on being mass produced and manufactured

in manufacturing settings, making it more of a product

and commodity. And because of their smaller size these

units cannot afford the regulatory expense of needing to

be certified in every country that they enter into. So,

finding regulatory harmonization is key to SMR success

going forward. What we have done here in Canada as the

Canadian Nuclear Association is to begin working with our

sister organization in the US, the NEI, and we have set up a

US-Canada regulatory task force that is looking at these

issues. But more importantly our regulators, the CNSC

here in Canada and the NRC in the United States have

signed a Memorandum of Cooperation and they are

working on regulatory harmonization. So, we recognized

the need here in north America for this standardization. At

the same time, we have reached out to the Nuclear Industry

Association in the UK and we are working with them as do

our governments on these same issues. We have now

signed a Memorandum of Understanding with our

counter part in Europe, Foratom, and we will be talking

about similar issues. But right now, the most developed

push on this front is between Canada and the United States

and has started with the UK and we hope to expand this to

Europe as well.

Is this the major aspect of the MoU with Foratom or

are there other objectives too?

There are other objectives as well. Firstly, the nuclear

cooperation between Canada and Europe goes back for

decades and specifically Canadian CANDU reactors have

been in service in Romania for nearly thirty years. So, this

MoU at the highest level addresses the need for greater

dialogue and the exploration of the role of nuclear in

effective environmental stewardship and a subtext to that

would be this work that we have to do in rationalizing

regulation around SMR. But the MoU has essentially three

components to it: one is around advocacy and trying to

advocate for more explicit inclusion for nuclear energy in

Canada and the EU and that includes the idea of sustainable

finance, taxonomy which I know that the European Union

is grappling with right now. The second point is that we


“I am Personally Very Excited About Canadas’s Positioning as a Tier One Nuclear Power and also as a First Mover in Small Modular Reactors“ ı John Gorman

atw Vol. 66 (2021) | Issue 3 ı May


want to support innovation, particularly in SMR and

advanced reactors which is something we flagged in the

MoU and the regulatory work also falls into that. And we

also want to find initiatives where we can work together to

promote nuclear as a clean source of electricity that is

needed for climate goals.

But what I wanted to say about this idea of taxonomy

and that nuclear is clean and the importance of that: the

nuclear industry in Canada

The nuclear industry in Canada like in

other nations has had to work very

hard with stake holders and policy

makers to explicitly acknowledge

nuclear power as clean energy and

we have succeeded in that in Canada.

like in other nations has had to

work very hard with stake

holders and policy makers to

explicitly acknowledge nuclear

power as clean energy and

we have succeeded in that

in Canada. So, recently just

before Christmas the federal

government explicitly identified

nuclear as clean and essential to net zero 2050. And

for us this has been important as we see in this increasingly

carbon constrained world all of the policies and

funding programs are increasingly directed toward clean

technologies. We worked very hard for that and I am

hoping that we can share some of the experiences and

lessons that we learned here in Canada around this issue

with Europe through our collaboration with Foratom.

A last time back to the SMR projects: How far advanced

are the projects trying to demonstrate the

feasibility of new kinds of reactor designs?

SMR are going to enter the market in Canada much sooner

than people expect. Our largest utility, Ontario Power

Generation, has announced that it will be net zero by 2040.

But as part of that it will connect its first SMR at its Darlington

Facility in 2028. SaskPower, Saskatchewan Power, is

working in partnership with them to roll out multiple units

in Saskatchewan with the same technology right on the

heels with OPG. And we have other technologies, including

very small reactor technologies, that are projecting that

they will be in the market even sooner, by 2026. There is an

amazing story here about the application of very small reactors

in a number of Canadas most important sectors. The

market demand in Canada for very small reactors is about

5.3 billion Dollars between 2030 and 2040. And much of

that market demand is in the mining industry using SMRs

for their high temperature heat, to generate electricity but

also to produce hydrogen. Many of these SMRs are going to

be used in heavy industry like cement and steel, fertilizer

production, in the oil sands, which is such an important

part of our economy. These SMRs are going to be used to

generate high temperature steam to clean up the extraction

process for oil and gas.

So, Canada is not only a first mover in SMRs but it has a

set of industries that are able to take advantage of the

unique capabilities of SMRs while decarbonizing those

sectors and ensuring that Canadas natural resource sector

and the materials that we produce are going to be

competitive in this increasingly carbon constrained world.

It is really a beautiful dynamic that we have here in Canada

of being able to develop a handful of SMR technologies

that are going to be tailor made to address the particular

GHG reduction issues in our industries. And our hope of

course is that we will be able to use those technologies to

help other nations decarbonize their heavy industries and

natural resource sectors so that we can contribute to the

world moving to a low carbon economy.

And finally, I want to come to nuclear waste

management. What are Canadas plans for waste


Readers of atw surely will know that the nuclear industry

is a very responsible manager of nuclear waste and that the

facts on spent fuel are actually quite a positive story. We

are the only energy generating sector that is entirely

responsible for the all of the byproducts that it produces

and we prepay for its safe management

and storage. We don’t emit

pollution to the environment and

we produce so little spent fuel

because uranium is so power dense.

We have been operating for

60 years providing 15 per cent of

the nations electricity and we

barely fill up a few hockey rings to

the floor boards with spent fuel. It

is exceptionally well managed, no one has ever been

harmed, let alone killed by spent fuel. If you look at our

entire life cycle from uranium mining to storing the spent

fuel and all of our byproducts, we have the lowest carbon

footprint of any electricity generating source, only wind is

comparable. We have an amazing story to tell on that front

that people don’t understand.

But we also recognize that we need a permanent

solution for storing the waste. We have been managing the

waste exceptionally well to this point but especially in

Canada where we are extending the life of our nuclear

plants for another 40 years and because of the advent of

SMR we need a permanent storage for the waste. So, there

are currently two communities, two land-locked areas that

have been short listed for a deep geological repository,

South Bruce in southern Ontario and Ignace in northwestern

Ontario and we have a nuclear waste management

organization that is overseeing the site selection for

this area. We are going to follow the example of Finland

here which is on track to have their DGR by 2023 and we

are going to continue managing our spent fuel until that

deep geological repository is completed. Another thing

that we are excited about is that a number of the technologies

that are reviewed and hopefully licensed here in

Canada will also be reusing the spent fuel from the CANDU

reactors as their fuel which adds some additional avenues

for properly storing or using the spent fuel.


Nicolas Wendler

Head of Media Relations and Political Affairs

KernD (Kerntechnik Deutschland e.V.)



“I am Personally Very Excited About Canadas’s Positioning as a Tier One Nuclear Power and also as a First Mover in Small Modular Reactors“ ı John Gorman

atw Vol. 66 (2021) | Issue 3 ı May

Nuclear Power is Dead,

Long Live Nuclear Energy!

Simon Wakter

The supposed demise of nuclear power has long been asserted by those opposed to the technology. But as the world

struggles to meet the Paris Agreement climate goals of limiting global temperature increase by 1.5 °C to 2 °C compared

to pre-industrial levels, neither the historic contribution nor the important future role of nuclear energy should be

ignored. Nuclear is an indispensable tool to meet the dual challenge of meeting an increasing energy demand while

phasing out fossil fuels. To paraphrase the speech of Robert Cecil at the final meeting of the League of Nations – nuclear

power is dead, long live nuclear energy!

Many countries have made pledges to decrease emissions

or set net zero goals by the year 2050. This leaves just

under 30 years to dramatically reduce emissions, while

global energy use is expected to continue rising. As pledges

are often phrased in terms of reductions in relation to 1990

emission levels, it also means that just over 30 years have

passed since the ‘benchmark’ year. In those 30 years, the

share of fossil fuels in both electricity and total energy

consumption has remained virtually unchanged, at around

65 percent and 85 percent respectively. The share of

nuclear energy in electricity production today is around

ten percent, a drop from a high of 17.5 percent in 1996. The

drop in nuclear production is only in terms of the share of

total production – nuclear electricity production has

actually increased in absolute terms, but world electricity

demand has roughly doubled in the same period. Total

energy demand has increased by about 60 percent.

Higher energy and electricity consumption is correlated

with higher development and human welfare indicators.

The increased access to and use of electricity has contributed

greatly to the improved standards of living for

hundreds of millions of people. But many people still lack

access to electricity and much of the worlds electricity and

energy consumption is still fossil fuelled. As has become

abundantly clear, energy production must increase but

must also be clean.

Globally, the combined share of low carbon technologies

amounts to approximately 35 percent of total

electricity production. Nuclear accounts for 30 percent of

this low carbon electricity, second only to hydro power’s

46 percent. In advanced economies, nuclear energy

supplies 40 percent of low carbon electricity. 1,2 Within the

EU, just over half of electricity is produced from low carbon

technologies and nuclear supplies almost half of this clean

electricity. 3

The world now faces the enormous, twofold challenge

of transitioning to clean energy while meeting the increase

in energy and electricity demand.

| Figure 1

Low carbon electricity generation in advanced economies in 2018. 1,2

added on top of the daily trials of coronavirus lockdown.

The lack of electricity, frequent blackouts and interruptions

to internet and running water made working or

studying from home virtually impossible.

In Japan, a cold spell coupled with an already tight LNG

market in Asia brought power prices to record highs.

Intraday power prices reached over ¥250/kWh, or roughly

€2/kWh, with spot prices topping out at around

¥155/kWh, or €1,20/kWh.

In Texas, arctic temperatures brought electricity

demand surging toward all-time highs and prices topped

out at over $9,000/MWh, or €7,700/MWh. When power

plants (primarily gas power plants) dropped from the grid

due to the cold, grid operators initiated rotating outages

which then turned into lasting blackouts for millions of


Both in Texas and in Japan, utilities as well as consumers

have been hit by the record breaking prices leading to

extraordinary corporate and personal financial difficulties.



Energy enables modern lives

Access to affordable energy is the foundation of modern,

civilised societies. The ability to use energy when and

where it is needed enables almost every other human

activity. This has been illustrated and reinforced by events

during the past year. In Libya, already strenuous conditions

have worsened through prolonged power outages

Electricity is key

The key to solving a large part of the decarbonisation challenge

is electricity. Dramatic cost reductions in wind and

solar production has redrawn the map and enabled a large

scale roll out of clean electricity only ever before seen in

the nuclear energy programmes of countries such as Sweden

and France.

1 Nuclear Power in a Clean Energy System, International Energy Agency (IEA), May 2019

2 European Commission Joint Research Centre, Technical assessment of nuclear energy with respect to the ‘do no significant harm’ criteria of Regulation (EU) 2020/852

(‘Taxonomy Regulation’), Petten, 2021, JRC124193

3 Eurostat, Electricity production by source, EU-27, 2019, https://ec.europa.eu/eurostat/statistics-explained/index.php/Electricity_generation_statistics_–_first_results

Serial | Major Trends in Energy Policy and Nuclear Power

Nuclear Power is Dead, Long Live Nuclear Energy! ı Simon Wakter

atw Vol. 66 (2021) | Issue 3 ı May


Electrification also brings with it great potential for

improvements in efficiency. For example, the electrification

of transportation through electric vehicles offers

significant efficiency improvements compared to fossil

fuelled cars.

Large scale production of hydrogen through electrolysis

enables the decarbonisation of several industry processes,

such as iron production. Direct electrification through

Electric Arc Furnaces, EAF, enables fossil free steel


It’s a power grid, not an energy grid

Electrification is a versatile tool for decarbonisation, but

places high demands on the power grid. Analysing and

designing systems based on the required energy on a yearly

basis is not sufficient.

Before transmission of power through alternating

current was discovered by Nikola Tesla at the end of the

19 th century, so called flatrod systems (German: Kunstgestänge

or Stangenwerk) were used to transfer power.

Flatrod systems, made up of timbers which were tied or

joined together, made it possible to transfer power both

horizontally and vertically over distances up to a few


Similarly to the flat rod system swinging back and forth,

alternating current is based on the current constantly

changing direction. Just like the flatrods, it is the oscillations

that transmit the power. In Europe, the oscillation

takes place 50 times per second and must always stay at

this constant frequency. A multitude of instrumentation

and control systems are in place to make sure the system is

always balanced – the production and load must always be


The economic market for trading, called the power

market, is not really a market for power but rather for

energy. Energy becomes a commodity to be produced,

distributed and consumed. This step away from the

physical concept of energy enables competition but also

brings difficulties.

In order to function properly, and in turn enable the

market, the power grid also requires balancing and

ancillary services. Such services may consist of inertia,

reactive power or short circuit power, all of which have so

far been provided largely for free by large generators such

as nuclear power plants. While markets exist for some

services, e.g. for frequency reserve measures, it is likely

that new markets for such services will be necessary in the

future to ensure the functioning of the power system. 4

Nuclear can already provide many of these services

today and with the right incentives it is possible to expand

the services, e.g. through integrating thermal storage with

molten salt in advanced reactors.

It’s not all electricity

Electrification is key to decarbonisation, but does not

paint the full picture. Some sectors, e.g. energy-intensive

industry and heavy-duty transportation (such as long-haul

aviation, maritime shipping and some road freight), are

| Figure 2

Global greenhouse gas emissions by sector. 4 This is shown for the year 2016 – global greenhouse gas emissions were 49.4 billion tonnes CO 2 eq.

4 Ritchie, H.; Our World in Data – Sector by sector: where do global greenhouse gas emissions come from? https://ourworldindata.org/ghg-emissions-by-sector

Serial | Major Trends in Energy Policy and Nuclear Power

Nuclear Power is Dead, Long Live Nuclear Energy! ı Simon Wakter

atw Vol. 66 (2021) | Issue 3 ı May

more challenging to decarbonise and will require greater

effort and novel approaches. These sectors, heavy industry

and heavy-duty transports, make up almost one-third of

global carbon emission.

Iron and steel production makes up seven percent of

greenhouse gas emissions. The emissions stem from two

sources – from the fossil fuels used to heat and power the

process, and from the coking coal used as raw material in

the reduction process itself. Low carbon energy can replace

the fossil fuels used to power the process, and clean

hydrogen can replace the coking coal used for the reduction

of oxygen in the iron oxide. Hydrogen is also an important

feedstock in ammonia and fertilizer production as well as

for refining fossil fuels, biofuels or plastics. This hydrogen

demand, today around 70 million tons per year, is currently

met almost exclusively by production from fossil fuels.

The production of cement produces around three

percent of global greenhouse gas emissions. Again, the

emissions stem from two sources. In this case roughly

60 percent of emissions are inherent to the calcining

process itself, while the remaining 40 percent arise from

the use of fossil fuels for heating the production process.

Electrification and fossil free fuels can replace the fossil

fuels, but emissions inherent to the calcining process will

require carbon capture technologies.

A large part of transportation can most likely be solved

through electrification, but heavy-duty transportation will

require higher density energy storage or fuels. This could

be in the form of hydrogen, ammonia or other electrofuels

such as synthetic hydrocarbons which can be made

through the Fischer-Tropsch process, combining carbon

monoxide (from carbon capture) and hydrogen into liquid


Energy use in buildings is another major sector, behind

almost one-fifth of emissions. Although electrification is a

major part of the solution, a large share of the property

stock relies on fossil gas for heating. Replacing gas boilers

with ground source or air source heat pumps could prove

prohibitively expensive – especially for those in energy

poverty, already struggling with a “heat or eat”-dilemma.

Existing grids, built for gas heated buildings, would

struggle to serve the increased power demand during cold

or hot spells. Hydrogen, either replacing or mixed into existing

gas pipelines, and district heating have both been

proposed as solutions.

The scale of energy use in buildings is often overlooked.

For example, final energy consumption for heating in

German residential buildings is roughly equal to the total

German electricity production, approximately 560 TWh

per year. Since 95 % of this heating demand is met with

fossil fuels, heating the country’s 40 million homes

produces almost ten percent of Germany’s greenhouse gas

emissions. Even partially meeting this energy demand

with clean hydrogen would require an extraordinary

amount of electricity for electrolysis – hydrogen from fossil

methane is not carbon neutral, especially when accounting

for flaring and fugitive emissions – meaning electrification

and district heating may prove to be more sensible

solutions. Nuclear CHP plants could provide cities with

both electricity and district heating, which is already done

at several locations today. District heating reactors, that

produce only heat and not power, are also being developed

and constructed.

All in all, industry and transport together with energy

use in buildings make up almost 60 percent of global

emissions. Nuclear is an important tool in these “hard-toabate”


Small solutions to big problems

A new wave of modern small and advanced modular

reactors are currently being designed, licensed and built

all over the world. These reactors have increased passive

safety features, reduced or no emergency planning zone

and significant potential for cost savings.

To compensate for lack of economies of scale, otherwise

associated with larger reactors, smaller reactors take

advantage of simpler construction principles, modularity

and standardisation to decrease cost. The smaller size also

decreases initial capital expenditure, construction time

and overall risk. This creates a feedback loop which works

to decrease the overall cost of capital, which for traditional

large scale reactors can account for up to 70 percent of

total costs.

More is more when it comes to heat output

Many advanced reactors work at significantly higher

temperatures than conventional reactors. Where today’s

boiling and pressurised water reactors work at temperatures

around 300 °C, advanced reactors cooled with

molten lead, sodium or gas work at temperatures between

500 and 700 °C. This means higher efficiencies and opens

up a range of new applications.

Advanced nuclear reactors, providing high temperature

heat and electricity now become an attractive option for

hydrogen production, process heat, district heating,

desalination and carbon capture through direct air capture

(DAC). Nuclear energy can be integrated across the

manufacturing process in many applications, e.g. for

production of iron and steel where high temperature

electrolysis, electricity production and large amounts of

high temperature heat can dramatically reduce emissions

and improve efficiencies.

Coal power remains largely unthreatened as the world’s

main source of electricity production, with global output

increasing to over 4,630 TWh in 2020 5 . One solution, as

explored in an article by Qvist et al. 6 , is “retrofit decarbonisation”

– a term which includes repowering of coal

units with low-carbon energy technology. The prospect of

| Figure 3

Steam temperature comparison, nuclear and coal power plants. 6


5 Ember, Global Electricity Review 2021, https://ember-climate.org/project/global-electricity-review-2021/

6 Qvist, S.; Gładysz, P.; Bartela, Ł.; Sowiżdżał, A. Retrofit Decarbonization of Coal Power Plants—A Case Study for Poland. Energies 2021, 14, 120.


Serial | Major Trends in Energy Policy and Nuclear Power

Nuclear Power is Dead, Long Live Nuclear Energy! ı Simon Wakter

atw Vol. 66 (2021) | Issue 3 ı May


advanced reactors capable of high temperature output,

suitable for existing coal powered steam turbines, and the

fact that more than half of the world’s 2,000 GWe coal fleet

is less than 14 years old combine to create a compelling


Integrating and reusing the existing site, equipment

(cooling water systems and steam cycle) and grid connection

could lower upfront capital costs by 28 – 35 percent

and levelized cost of electricity by 9 – 28 percent compared

to a greenfield installation.

Standardisation, harmonisation, cooperation

To realise the potential of small and advanced modular

reactors it is essential to avoid unnecessary, countryspecific

design modifications or changes to documentation.

Policymakers and regulators must work to ensure

stability and predictability in the licensing process as well

as to increase international harmonisation of licensing


Redesigning SMRs for each country would quickly

become prohibitively expensive, which means licensing

regimes need to be performance-based rather than

prescriptive. Licensing should also be risk-informed and

technology-inclusive. In the cases where that is difficult or

not possible it is important that regulators agree on

terminology and definitions, possibly through a taxonomy

of licensing requirements. One example is the definition of

active and passive systems, which has varying definitions

between different countries and different organisations.

Increasing standardisation and harmonisation through

international cooperation is a low cost, no-regrets option

for countries wishing to expand the use of nuclear energy.

Enabling nuclear energy

Nuclear energy is a flexible solution which can help solve

many challenges – providing electricity and heat for

several applications ranging from industrial process heat,

through hydrogen production to carbon capture and

production of electrofuels. Nuclear also provides firm

power and grid stability, aiding in the integration of

variable renewable energy sources.

In addition to contributing to the historic and future

decarbonisation of energy use in the west, expansion of

nuclear energy is a promising solution for economies in

transition and developing economies seeking to improve

living standards while reducing greenhouse gas emissions.

Over 30 “nuclear new-comers” have concrete plans to

develop nuclear energy projects in the coming decade.

Recent research by Kenton de Kirby and Jessica Lovering

offer important insights and lessons on how to enable the

success of nuclear energy in emerging markets.

In their report 7 , de Kirby and Lovering find that local

opposition to projects in emerging markets differs from the

anti-nuclear movement of the 1970’s which, in highincome

countries, has protested nuclear on ideological and

absolutist grounds. The authors warn against projecting

fundamental anti-nuclear sentiments onto activists in

newcomer countries. Instead, local opposition is largely

based in a worry about livelihoods, lack of local economic

benefit and government corruption as well as the government’s

inability to respond effectively in the event of an


To gain public trust and consent, stakeholders must

establish strategies and take concrete action to improve

transparency, involve the local community and work to

understand activist’s concerns – all while addressing

perceived risks and building trust in regulators and

relevant institutions. The report goes on to offer concrete

ideas and best practices for effective engagement with

local communities.

Nuclear power is dead,

long live nuclear energy!

From harmonisation and standardisation of licensing

requirements in established nuclear energy countries to

stakeholder engagement in emerging economies, nuclear

energy (like other clean energy technologies) must be

enabled through proactive work from politicians, policymakers

and international institutions.

75 years ago, in the spring of 1946, Robert Cecil

participated in the final meeting of the League of Nations

in Geneva. Lord Cecil was one of the architects of the

League and participated during the creation of the United

Nations. He ended his final speech at the meeting with the

words: “The League is dead, long live the United Nations.”

Whether the world successfully eradicates global

poverty while managing climate change will be largely

determined by the events in emerging markets. Nuclear

energy is an indispensable tool to meet the dual challenge

of increasing energy consumption while phasing out fossil

fuels. Just as the League was succeeded by the United

Nations, formed to meet new challenges, so our view of

nuclear must grow to meet the challenges that lay ahead.

To paraphrase the speech of Robert Cecil – Nuclear power

is dead, long live nuclear energy!


Simon Wakter

Expert Advisor, Energy

Simon Wakter is a nuclear energy engineer working as Expert Advisor in energy

systems at the consultancy firm AFRY, with experience from technical consultancy in

nuclear safety and licensing as well as from advising on different projects ranging

from SMRs to hydrogen. Mr. Wakter is also a board member of the Swedish Nuclear

Society and one of the founders of the Swedish Ecomodernists.

7 de Kirby, K; Lovering, J. A Socially Sustainable Future for Nuclear Energy in Emerging Markets, 2021


Serial | Major Trends in Energy Policy and Nuclear Power

Nuclear Power is Dead, Long Live Nuclear Energy! ı Simon Wakter

atw Vol. 66 (2021) | Issue 3 ı May

Europe on the Road to a Major Disaster

When Physics and the Laws of Nature Are Disregarded,

a Rude Awakening Looms

Herbert Saurugg

Introduction The European electricity supply system is undergoing a radical upheaval. What is essential in terms

of climate protection policy is leading to the interconnected system becoming increasingly fragile, because the approach

which is being adopted is non-systemic. Instead of sound basic knowledge, it is wishful thinking and knee-jerk reactions

which are determining the approach, and this could end in the greatest catastrophe since World War II.

We can still turn away from this disastrous

route. This would require rapid

and decisive political action, but there

is no evidence of this at present. A

systemic conversion of the European

electricity supply system into robust

energy cells would have to be initiated

immediately to reduce the looming

susceptibility to failure. From a

technical point of view, this would not

be a problem, since the necessary

knowledge is available and this

conversion could be undertaken while

the system is in operation.

The greatest obstacle here is the

fact that we have so far successfully

thought in terms of large-scale

technology, and this would have to be

supplemented by complementary

complexity and networked thinking,

and adopted as the maxim. This

requires appropriate framework conditions.

The current route is pointing

more in the opposite direction, however,

towards centralization, but this

makes it impossible to manage a system

which is becoming increasingly


The electricity supply is our most

important lifeline, without which our

modern society could be destroyed

within only a few days. We ought to

prevent this from happening.

On January 8, 2021 we experienced

the second most serious

major disruption so far in the

European power supply system

(ENTSO-E/RG CE – Regional Group

Central Europe). The consequences

were very minor compared to the

first one on November 4, 2006. On

that occasion, around 10 million

households in Western Europe had

to be disconnected from the grid

within 19 seconds to prevent a

pan-European blackout. This time,

those affected were “only” large

commercial customers in France

and Italy which had contractually

agreed to be disconnected should

such an incident occur. The precautionary

and communication

measures of the 43 European transmission

system operators, which

have continually been improving

the situation since 2006, meant the

disruption could be rectified after

about one hour. Hardly anybody

had expected yet another major

disruption. Despite everything,

nobody knows whether the security

mechanisms which have been

designed will also be effective when

the next incident takes place.

The worst case would be a pan-

European electricity, infrastructure

and supply outage, a so-called

blackout, as is expected by the

Austrian Armed Forces or the

author, within the next five years.

In the European interconnected

system, the expenditures needed to be

able to maintain grid stability have

been increasing for many years. The

Austrian bottleneck management

costs, i. e., the expenditures to avert

an imminent blackout, have ballooned

from 2 million euro in 2011 to

346 million euro. Instead of 2 interventions,

interventions were necessary

on 301 days within a few years.

Although these expenditures fell

slightly in 2019 and 2020, they are

still far too high. This is primarily

down to the fact that the system does

not adjust to the framework conditions,

which have changed considerably

in the meantime, and also

the necessary transition to renewable


| Figure 1

ENTSO-E/RG CE – Regional Group Central Europe.

Lack of storage systems

and buffers

Wind and sun are not always available,

and there are sometimes significant

deviations between forecast and

actual production. In a system where

the balance between generation and

consumption has to be maintained for

31,536,000 seconds per year, this is

an enormous challenge, particularly

since there is a lack of systemsupporting

storage systems and

buffers. This situation can only be

remedied by large-scale power station

interventions, but this does not represent

a permanent solution and incurs

high costs. In addition, the susceptibility

to failure of the whole system is

increasing because it is permanently

under stress.

Whereas in Austria around

3,300 GWh of pumped storage capacity

is theoretically available, the

whole of Germany can muster only

around 40 GWh. And there are no

plans for expansion which are worth

mentioning. With electricity consumption

currently at 60 to 80 GW,

Germany would not be able to cover

even one hour of its own electricity

consumption. Quite apart from the

fact that this would not be technically

feasible, because only around 11 GW

of bottleneck power is available. In the

whole of Europe, storage systems with

a turbine capacity of around 47 GW

are currently available, two thirds of

this with a pumping option to refill the



Energy Policy, Economy and Law

Europe on the Road to a Major Disaster ı Herbert Saurugg

atw Vol. 66 (2021) | Issue 3 ı May


storage reservoirs when surplus

electricity is available. This can cover

or temporarily store only a fraction of

European consumption.

The issue of storage ranges from

inherent to seasonal, which requires

different technologies. The transition

to renewable energy so far has disregarded

the fact that conventional

power stations have the storage

integrated in the primary energy

( nuclear fuel rods, gas, coal, oil), thus

making it possible to balance the

continual changes in consumption.

But now we have increasing, and

increasingly more difficult to forecast

consumption, and volatile electricity

generation at the same time. Two

things which cannot be reconciled

without appropriate storage systems

and buffers.


Power-to-X, especially the use of

hydrogen, is deemed to be very

promising for seasonal storage. In

principle, it sounds very tempting,

since an existing infrastructure would

already be available - the gas grid. The

fact that a number of big challenges

remain to be solved is usually not

mentioned. Least of all the costs. The

announcement of a large wave of

financial support triggered a goldrush

mood and an avalanche of further

announcements. It is to be expected

that a gold nugget or two will indeed

be found. But people should not really

expect that a great breakthrough and

widespread implementation will be

possible within the next few years.

What we do need are solutions that

can be implemented rapidly, not only

in 10 to 20 years’ time. On the other

hand, we still know relatively little

about the potential side effects of the

water vapor which is released in huge

amounts as the hydrogen is being

reconverted to produce electricity.

And even more attention needs to be

paid to this aspect with the planned

methanation, since we already know

the effects here, because methane is

significantly more harmful to the environment

than CO 2 .


The general principle is that there is

no form of energy which would not

have any side effects. Enormous

resources are required for wind and

PV systems as well, but people usually

have a distorted perception of this,

unfortunately. The individual system

is small and manageable. But if one

considers the actual performance and

extends these considerations to cover

| Figure 2

Turbo-generator set of a thermal power plant. (Source: Foro de la Industria Nuclear Española)

a period of one year, a very different

picture emerges. The wrong way of

thinking often leads to apples being

compared with oranges, or to average

values being used. But all that is

relevant for the operation is the

contribution that one specific type of

energy generation can guarantee in

order to maintain the necessary

permanent balance. This means not

calculated as a statistical average over

the year, but plannable, reliable and

constant. If that were to be done, one

would very quickly recognize that it

requires much more than simply a

production plant.

This is precisely the way of thinking

that is necessary to be able to ensure

the systemic restructuring of our most

important lifeline. Our either/or

thinking will not get us anywhere

here. We need both/and thinking to

master the challenges we are facing.

CO 2 emissions can be significantly

reduced with renewable energies, but

at the same time we also need other

elements in the system to be able to

continue to guarantee the very high

security of supply to which we have

hitherto been accustomed.

Instantaneous reserve

Another technical detail which is

hardly ever considered concerns

the instantaneous reserve, i.e., the

rotating masses of conventional power

stations. When nuclear and coal-fired

power plants are shutdown, these

reserves are also disconnected from

the grid on a grand scale. The gyrating

masses of the synchronous generators

play a key role for the frequency

generation and maintenance, since

mechanical energy is thereby continuously

converted into electrical

energy and vice versa without the

need for controlling interventions. A

purely physical process. They can also

be thought of as large shock absorbers

for load shocks, which have so far

ensured that the operation of the

European interconnected system has

been so stable. These shock absorbers

are now being removed and not really

replaced, which makes the whole

system more susceptible to failure.

The instantaneous reserve is at the

same time also an inherently available

energy storage system, which can

temporarily buffer any short-term

energy surplus. The generated frequency

of the alternating current

therefore also always indicates

whether there is a lack of power or

a surplus of power in the system overall.

IT-independent control interventions

can therefore be specifically

performed via the frequency, and the

system overall kept stable.

Implementation speed

Approaches which utilize large

system-supporting storage batteries

and corresponding power electronics

already exist, and are already being

used in Southern Australia, Great

Britain and now also in Texas, for

example, to reproduce and compensate

the instantaneous reserve. It

is supplementary, however, and will

never be able to replace the complete

instantaneous reserve. Here again, a

both/and mindset is crucial. In the

ENTSO-E RG CE grid, these systems

first need to be implemented on a

grand scale, however. As is often the

case, the sticking point is not the

knowledge or the technology, but the

implementation. This would have to

take place at the same speed as the

other measures are being taken.

Germany is going it alone

The biggest problem is that Germany

in particular is taking the second step

before the first: Conventional power

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Europe on the Road to a Major Disaster ı Herbert Saurugg

atw Vol. 66 (2021) | Issue 3 ı May

stations are being shut down in

large numbers without an equivalent

replacement being available. The

emphasis so far has been placed on

the rapid expansion of wind and PV

power stations or providing massive

financial support for them. But what is

missing here is the indispensable

system adjustment, starting with the

lack of storage systems and buffers,

and continuing with the lack of

trans mission possibilities, i.e., lines.

In addition, the electricity no longer

has to be distributed in a one-way

system only, because those who

were pre viously consumers have now

increasingly become producers as

well, i.e., so-called prosumers, and

therefore there are also load flows in

the opposite direction, for which the

system and the protective devices

were never designed.

In Germany, it is also assumed, at

least in the current planning documents,

that in the future, electricity

can simply be imported from its neighbors

when needed. But somebody else

might just have a thing or two to say

about that. Because: Where is the

electricity going to come from when

these countries have already been

importing electricity from Germany

when they have had shortfalls? In

addition, conventional power stations

are being shutdown everywhere. And

the idea that the wind will always be

blowing somewhere is a myth which

does not withstand scrutiny. Quite

apart from the fact that the transmission

infrastructure would still be

needed, and this was never built for

large-scale electricity exchange. The

desire for Europe to be a single

conductive sheet of copper is understandable,

but bears no resemblance

to reality and ignores physical framework


Decentralized functional units

Moreover, millions of tiny power

stations and new actors can no longer

be controlled using the centralized

structure and logic which has previously

been successful. What is

required instead is an “orchestration”

of this multitude of components and

actors which, with the self-organization

of a “swarm”, will then automatically

play their part in ensuring the

security of supply by having a view of

the situation in the overall system

which is accessible to all. This requires

it be restructured into so-called robust

energy cells, however, since the increasing

complexity will not be

manageable otherwise. For complex

systems cannot be centrally controlled,

they require decentralized autonomous

units, where demand, storage

and generation are balanced locally or

regionally if possible, and not as at

present, where problems are shifted

around across a wide area. Crosssystem

synergies (electricity, heat,

mobility) must be used as well. The

issue is therefore a holistic energy

supply in cellular structures, which

first requires a rethink in many places.

Such an approach is not inconsistent

with the previous large-scale

system, which will still be required as

before, since it will not be possible to

supply large consumers such as large

industrial enterprises or cities in other

ways for some time yet. But these

decentralized structures and functional

units do enable us to enhance

the robustness of the overall system

bottom-up and while it is in operation,

without interruptions. Cellular structures

are not as efficient as the largescale

system we have had to date, but

this holds true only as long as there is

no major disruption in the form of a

blackout. In such a case, all previous

gains in efficiency would be destroyed

in a single blow and incredible societal

damage would be caused. Resilience

and robustness require redundancies

and reserves, and are therefore generally

in conflict with the efficiency

mindset, which is driven mainly by

economic considerations.

No such thing as one-hundred

percent security

Moreover, there is simply no such

thing as a failure-proof system, as the

European transmission system operators

stated clearly and unequivocally

in their investigative report on the

blackout in Turkey: “A large electric

power system is the most complex

existing man-made machine.

Although the common expectation of

the public in the economically

advanced countries is that the electric

supply should never be interrupted,

there is, unfortunately, no collapsefree

power system.”

Increasing complexity

We should therefore learn from

nature, where all living things are

organized in cellular structures. This

has obviously been tried and tested

and has survived through time. For

what is being celebrated as a decentralized

transition to renewable energy is

currently anything but decentralized.

The whole transition to renewable

energy to date only works because of

the existing centralized system with

the requisite storage systems and

buffers. The proposed smart grid and

flexibilization measures also depend

on a comprehensive, cen tralized IT

network and thus on an increasing

degree of complexity. Thus, in addition

to the risk of cyber attacks, the

result is additional, hardly noticed

side effects.

Complex systems

Complex systems exhibit a number

of unpleasant characteristics which

cannot be managed with our linear

way of thinking and machine logic

which has succeeded so far. As the

number of actors and the networking

increases, so does the complexity and

thus the dynamics, which we can

observe on an ongoing basis, of

course. We can hardly keep up. At the

same time, the forecastability of the

system behavior worsens because

self-amplifying feedback processes

are possible, as can currently be seen

with the phasing out of coal power: An

increasing number of power plant

operators want to abandon coal early,

because their operation is no longer

profitable. At the same time, we have

more or less run down the overcapacities

which used to be available

during the past 10 years, which means

less and less scope for action remains.

Phase-out of coal and nuclear


At the beginning of January 2021,

those German coal-fired power plants

which had strictly speaking been

selected for early shutdown had

already to go onstream again, because

the demand could not be covered

sufficiently well. If Germany sticks to

its plans to phase out coal and nuclear

power, which is currently firmly

scheduled for the end of 2022, this

will already give rise to critical

windows in the coming months,

where regional shutdowns to protect

the system as a whole can no longer be

excluded. It is irrelevant here whether

it will nevertheless just work out

in 99.99 percent of the time. The

electricity supply system knows no

leeway here. The balance must be

safeguarded 100 percent of the time.

There is a risk the system will collapse


Lack of basic knowledge

It is unfortunately the case that in

many fields and among most of

the decision-makers, too, there is a

lack of the most basic knowledge

about the laws of nature, especially

the laws of physics, and also a lack

of technical know-how to understand


Energy Policy, Economy and Law

Europe on the Road to a Major Disaster ı Herbert Saurugg

atw Vol. 66 (2021) | Issue 3 ı May


the implications of often ill-considered

decisions. This situation is now

being compounded by the lack of

knowledge on how to deal with

complex systems, since this is not part

of our universal basic education.

Characteristics of complex


One further characteristic of complex

systems is that small causes can have

massive effects, as we are currently

experiencing with the coronavirus

pandemic. A virus turns the whole

world upside down in a matter of

weeks. The consequences of decisions

are frequently irreversible. A power

plant which has been shut down,

deconstructed, and decommissioned

is lost forever. It is very expensive to

maintain and reactivate power plants

which have been mothballed.

Non-linearity means that many of

our previous methods of risk assessment

fail. The delayed consequences

are particularly deceptive since people

like to ignore them. They include, for

example, the 50.2 hertz problem,

which arises when a large number of

old installations with inverters disconnect

from the electricity grid at the

same time, leading to a yo-yo effect.

This problem is supposed to have been

solved, but we do not know whether

this is actually the case. What we do

know is that it was ignored for far too

long. Neither is the effect immediately

noticeable with the instantaneous

reserve, or when power plants are

being shutdown. Things mount up

and there comes a point when something

happens which is the last straw

and can no longer be controlled –

small cause, great effect. And there

are no easy cause-and-effect relationships

which can clearly be made to

take the blame. Things have simply

built up over a lengthy period of time.

The collapse of complex systems is, as

has been well investigated, not a fault

but a system design characteristic to

facilitate a renewal. Economic theory

uses the term “creative destruction”.

The new can often develop only when

the old is broken or has been

destroyed. If adopted with our most

important lifeline, our electricity

supply, it would equate to an intention

to commit suicide.

meanwhile between 40 and 50 years

old. Some are even older. This means

that far-reaching changes will have to

be introduced in the next few years.

But the currently purely economic

considerations and the uncertain

framework conditions mean this is not

worthwhile. Postponing investments

is thus a popular move, but one which

increases the susceptibility to failure.

And when investments are made only

when it is worthwhile, it is already too

late. This explains why the liberalized

electricity market is also contributing

to reducing the reserves and redundancies.

What may be acceptable in

other types of infrastructure could

come to a nasty end if used for the

vital electricity infrastructure, as is

illustrated by the turkey illusion: A

turkey which is fed every day by its

owner assumes on the basis of its daily

positive experience (being fed and

looked after) that the owner only has

its best interests at heart. It lacks the

most important information that this

care serves only one purpose: On the

day before Thanksgiving, traditionally

the day on which the turkeys are

slaughtered, it gets a fatal surprise.

This metaphor comes into its own

with very rare events which have

enormous consequences, so-called

extreme events (“X-Events”) or strategic

shocks. In such cases, we like to

mistake the absence of proof for the

proof of absence.

Extreme weather events

As if this were not enough, we must

also expect that extreme weather

events will become more common in

Europe just as they already are in

Australia, California or Texas. This

also means we have to expect serious

damage to infrastructures and infrastructure

outages. The droughts of the

last few years in particular have posed

an enormous challenge for conventional

power plants, which have to

draw their cooling water from lakes

and rivers. At the same time, falling

water levels reduce the capacity of

hydroelectric power plants. In the

other extreme case, floods or torrential

rainfall events cause problems

with electricity generation, as

happened in June 2020, for example,

when a torrential rainfall event

knocked out the biggest Polish coalfired

power station and other generating

plants at the same time, leading

to a critical gap in supply.

Energy cells are also affected in

these situations, but the risk of sudden

and widespread outages could be

significantly reduced here. Cells do

not have greater security of supply

per se. But they do help to reduce

the potential damage, and this is

gaining in importance as a result of

the problems illustrated. Moreover,

we are still creating many even worse

dependencies and hence vulnerabilities

by developing a structure

which increasingly lacks borders.

Lack of predetermined

breaking points

The lack of clearly defined, predetermined

breaking points makes it

much more difficult to re-establish a

network. And this is precisely the

aspect that is to be extended even

more in the next few years. An EU

directive requires at least 70 percent

of the capacity of the border interconnectors

to be open for the crossborder

electricity trade by 2025.

Something which can boost competition

and thus lower prices on the

daily level leads on the other hand to a

massive vulner ability of the whole

system, because it means that less and

less consideration is given to the

physical limits. A possible inter ruption

can spread much faster and much

further. These directives are thus

clearly at variance with a robust,

cellular approach.

Aging infrastructures

The transition to renewable energy is

not the only reason we are facing a

time of great upheaval. The bulk of

the infrastructure will reach the

end of its service life over the next

few years. Most power plants are

| Figure 3

Turkey Illusion.

Energy Policy, Economy and Law

Europe on the Road to a Major Disaster ı Herbert Saurugg

atw Vol. 66 (2021) | Issue 3 ı May

Dangerous trade in electricity

The role played by the electricity trade

is paid too little attention on the

general level as well in respect of the

risks to the European interconnected

system. In June 2019, German

electricity traders brought the system

to the verge of collapse after they

exploited a loophole in the regulations.

Despite receiving a formal

warning and the prospect of high

penalties which now loom, loopholes

still seem to exist. In the first quarter

of 2021, there have already been over

60 frequency anomalies, which are

probably caused by economically

optimized power plant operational

planning. In the whole of 2020 there

were around 140 anomalies. The

problem is: On the hour and regular as

clockwork, half to two-thirds of the

reserve which has been held back in

order to be able to react to unforeseen

power plant outages is “consumed”. If

one or more power plant outages do

actually occur during this time, which

is more likely with the timetable

change, this could rapidly lead to a

further escalation. Although people

have long been aware of the problem,

the regulators do not seem to see the

need to prevent this misuse. This can’t

go on forever.

January 8, 2021

There are also several indications that

the two factors, the reduced instantaneous

reserve and the excessive

electricity trade, could have played a

significant role in the major disruption

on January 8, 2021, even if this has so

far not been mentioned in any publicly

available investigation reports.

At 14:04 on January 8, a bus

coupling was overloaded in the

Ernestinovo (Croatia) transformer

substation, which had then correctly

shutdown for its own protection. This

led to 13 other units in Southeast

Europe being overloaded, causing the

European interconnected system to be

separated into two parts. The result

was a massive increase in frequency to

50.6 hertz in Southeast Europe caused

by the massive power imbalance, and

a drop in frequency to 49.74 hertz in

Northwest Europe. In the Southeast

there was excess power of 6.3 GW,

which was simultaneously not available

in the Northwest.

The very steep drop or increase in

frequency indicates that too little

instantaneous reserve was available,

which should have cushioned such a

significant change in power. On the

other hand, there was an enormous

electricity transmission of approx.

| Figure 4

Phases of a pan-European electricity, infrastructure and supply outage (“blackout”).

6.3 GW towards Spain and France at

the same time. There are hence some

indications that the transregional

electricity trade could also have

played a role here, and led to the overload.

Another interesting point is that

the bus coupling in the Ernestinovo

transformer substation had not been

classed as systemically important up

to that point, and had therefore not

been incorporated into the con tinuous

safety calculations. This begs the

question of how many such unnoticed

breaking points could still exist. The

incident on January 8, 2021 should

therefore be understood as a warning

to be taken very seriously, even

though politicians immediately maintained

that the electricity supply was

secure. Thirty-six countries are all

sitting in the same boat, and if it

capsizes, they will all go down with it.

After a blackout

Austria is probably one of the first

countries which will be in a position to

re-establish a working power grid,

although this could still take about

one day or longer. It will take at least a

week before electricity is flowing

everywhere again on the European

level. But that is not all.

In general, the consequences and

restart times after a widespread and

sudden outage of the power supply

are massively underestimated. Many

preparatory measures deal only with

the immediate provisions for the

power outage, which usually leads to

the procurement or extension of an

emergency power supply. Albeit it that

the outage phase is still the most

manageable one. The considerably

longer phases (phases 2 and 3) as

systems are being restarted will have

much more serious and catastrophic

consequences in the other infrastructure

sectors and during the

resynchronization of the supply

logistics, and this is something which

is completely underestimated in

this dimension because we have no

experience of it.

It is primarily the very high security

of supply in all areas of our life, especially

in Central Europe, which will

backfire on us: There is a general lack

of self-sufficiency measures or fallback

solutions. Far too many people

and organizations simply rely blindly

on the continuous availability. A

turkey illusion.

Protracted restart

It is thus to be expected, for example,

that after the electricity supply

resumes, it will be several more days

before telecommunication services,

i.e., cell phones, internet, and landlines,

are back in operation, because

serious hardware damage and overloads

must be expected. This takes us

to week 2 at least if we are lucky, until

wide-scale production and goods distribution

can start up again. This does

not take account of the international

intermeshing in the supply logistics.

And neither the people nor companies

nor countries are prepared for this.

There is thus the threat of an inconceivable

catastrophe, which could end

in the biggest catastrophe after the

Second World War.

What can we do?

In the short term, the only thing that

will help is to prepare for the event,

which means (in a general sense as

well): Prevention and security are

important, but not enough. There has

to be both/and thinking here as well:

We also have to be in a position to deal

with unexpected events and get a grip

on them. This applies at all levels. For

example, preventing cyber attacks is

enormously important, yet an IT

recovery plan is indispensable, even if

you always hope it will never be

needed. But hope on its own is not

enough. The same applies in relation

to blackouts. We are currently undertaking

the biggest infrastructure

transformation of all times – as openheart

surgery and without a safety

net. It could turn out to be a fatal

evolutionary mistake.

The most important step begins

within your own four walls: Be able to

be completely self-sufficient for at

least two weeks, looking after yourself

and your family from your own

pro visions and supplies. This means


Energy Policy, Economy and Law

Europe on the Road to a Major Disaster ı Herbert Saurugg

atw Vol. 66 (2021) | Issue 3 ı May


2 liters of water per person per day.

After the outage, you can cook again

but it is not possible to go shopping. So

have provisions such as pasta, rice,

and tinned food for two weeks. The

same applies to important medi cation,

and food for small children and pets.

Torches, a battery-powered radio,

rubbish bags and other important

articles that you might need. In other

words, things you would take with

you on a 2-week camping holiday.

Very low level

of preparedness

Several investigations have shown

that around a third of the population

could be self-sufficient for a maximum

of four days, and a further third for a

maximum of seven days. This is the

beginning of a vicious circle, because

when people can no longer provide for

themselves to a sufficient degree, they

do not come into work to power up the

systems again. A vicious spiral is set in

motion. This explains why broadbased

self-sufficiency in the population

is an essential prerequisite for

being able to cope with such a

scenario. This especially also relates to

those organizations and companies

which must be able to maintain an

emergency service in such an event,

including the energy business.

Stand-alone PV systems

And many PV owners are not aware

that their PV system will not supply

any electricity either during the

outage, because most systems are

line-commutated. Only stand-alone

PV systems, i.e., those supplemented

with system decoupling, hybrid

inverters, and storage devices, can

maintain an emergency supply in their

own four walls even in the event of an

outage. So power could continue to be

provided for lighting, heating, and

the refrigerator/freezer (provisions!).

This would noticeably lessen the

impact of the scenario. From society’s

point of view, it would be even more

effective and more efficient to construct

regional energy cells as rapidly

as possible, thus ensuring that at least

a basic emergency supply in respect

of water, wastewater, heat or healthcare

services could be maintained.

even during an outage. This will

not happen, however, because the

necessary awareness and the

requisite framework conditions are


Organizational measures

The organizational measures which

are necessary can then build on these

personal precautionary measures.

This represents the first step towards

sensitizing a company’s own staff by

giving them a nudge to take their own

precautions. On the other hand, full

consideration is required as to how

the necessary communication can be

safeguarded in the event of a blackout.

In many cases, only offline plans,

i.e., prepared arrangements which

have to be available in the minds of

the staff, will work. Key staff have to

know what to do when nobody else

can be reached, and how the handover

and supply operates when an

emergency service has to be maintained.

Raising the alarm in the usual

way will generally not be possible

because most of the telecommunication

systems will go down within a

few minutes of the power outage. As

far as staff availability is concerned, it

is primarily their personal circumstances,

such as how far they have to

travel to their place of work, or other

obligations such as family members

who need to be looked after, offices

they hold in the local crisis management

group or emergency response

organizations, which need to be

considered. Moreover, an assessment

must be carried out as to how long the

available resources, for example the

fuel for emergency generators for

emergency operation, will last, since

there is little hope of external supplies

coming in if appropriate preparatory

measures are not taken. This continues

right through to restart plans,

where consideration must be given as

to the conditions which must prevail

before it is even possible for regular

operation to be resumed again.


The European electricity supply

system is currently going through a

time of radical upheaval, where the

crux is: “Too many cooks spoil the

broth.” This situation has arisen

because there is no systemic overall

coordination and approach. Each

member country is transitioning to

renewable energy in different directions,

and a coordinated approach is

difficult to discern. Furthermore,

fundamental physical and technical

framework conditions are being

ignored and replaced with wishful

thinking, and it is foreseeable that this

can only lead to disaster. After all, the

electricity supply system obeys only

the laws of physics. We can still turn

away from this disastrous route. This

would require quick and decisive

action, but there is no evidence of this

at present.


Herbert Saurugg

President of the

Austrian Society for

Crisis Preparedness



Herbert Saurugg is an international blackout and crisis

preparedness expert, President of the Austrian Society

for Crisis Preparedness (GfKV), author of numerous

specialized publications and a requested keynote

speaker and interview partner on the topic of

“A Europe-wide power, infrastructure and supply

breakdown (‘blackout’)”. For the past 10 years, he

has been researching the increasing complexity and

vulnerability of vital infrastructures and possible

solutions for making the supply of vital goods more

robust again. At www.saurugg.net he runs an

extensive expert blog on these topics.

Energy Policy, Economy and Law

Europe on the Road to a Major Disaster ı Herbert Saurugg

atw Vol. 66 (2021) | Issue 3 ı May

A Role for Nuclear

in the Future Dutch Energy Mix

Findings of a Study for the Dutch Parliament

Bojan Tomic and Mario van der Borst

Introduction The EU is embarking on the European “Green Deal”, with the target to be “climate neutral” by 2050.

With majority of EU greenhouse gas emissions coming from production and use of energy, all possible energy sources

warrant a new look. Facing the need for a drastic reduction of CO 2 emissions over the next couple of decades, while

having limited back up options for VREs a potential role of nuclear energy for the Netherlands in 2050 has been raised

by the Dutch parliament. Among seven questions raised by the Dutch parliament (motion Yeşilgöz-Zegerius/Mulder

(2018/2019 35167NR15) of specific interest were prospects and costs of new NPPs including SMRs, comparison with

other sources of electricity also considering CO 2 costs as well as potential scenarios including nuclear that are possible

for the Netherlands. Consideration of the security of supply, reliability, and flexibility as well as new development

including hydrogen cycle were important. To respond to the parliamentary motion, the Ministry of Economic Affairs

and Climate Policy of the Netherlands launched a “meta- study” to critically assess and compile information from

numerous reports while placing those in the specific Dutch perspective. Furthermore, the Study was to examine the cost

of electricity from nuclear power plants and other low-carbon electricity sources specifically for the Netherlands.

In their reports, most international

organisations, from IPCC over US EIA,

OECD NEA, WEC etc. favour deployment

of nuclear to cope with climate

change. Moreover, many see little

chance of full decarbonisation without

a significant contribution of nuclear.

This is in particular so for the countries

like the Netherlands where there are

no other possibilities (except fossil) to

complement the VRE (vari able renewable

energy) sources. This highlights

the need for a cost com parison that

would not just be based on the headline

LCOE (levelized costs of electricity)

than rather consider all the cost

drives, from the cost of financing a

source of electricity over the operating

costs including the system costs to the

cost of decommissioning and waste. In

this, the Study corrected some of

previous cost comparisons that often

excluded realistic system costs and/or

other subsidies available to VREs such

as grid connection, etc. Furthermore,

the effects of the “priority access” to

the grid were investigated. In particular,

the notion of a “level playing

field” was investigated, including

sensitivity studies to account for uncertainties

in some of the parameters.

Upon its publication and presentation

of the result in the Dutch

Parliament a lively debate commenced,

in the Chambers (and its committees)

but also in the media and among the

public. As expected, some of the

particular strong reactions came from

entities and interest groups representing

the VREs, which claimed that ENCO

study reached “wrong conclusion”,

while falling to establish technically

sound/justified arguments as what was

wrong in ENCO Study’s conclusion.

New nuclear power –

where do we stand

As of May 2020, 441 nuclear reactors

are operating in 31 countries, with

389,994 MWe total installed capacity.

Further 54 nuclear power reactors are

under construction, with a total of

57,444 MWe total net installed capacity.

Developing nations with increasing

energy needs and those

heavily relying on coal (e.g. China and

India) are leading the way in ad vancing

nuclear construction, based on own

and foreign technologies. Per IAEA,

about 19 countries are starting or

planning construction, and even countries

that have never employed nuclear

as an energy source, are reviewing

their position (e.g. Australian Parliament’s

report). The world nuclear fleet

generated 2,563 terawatt- hours (TWh)

of electricity in 2018, a 2.4 percent

increase over the previous year, which

was essentially due to China’s nuclear

output increasing by 44 TWh (+19 %),

but still 4 percent below the historic

peak of 2006.

At the end of 2019, nuclear

electricity constituted about 26 % of

the EU’s electricity generation. There

are 126 nuclear power plants. There

are active constructions of new NPPs

in 3 EU Member states, and up to

6 MS are pursuing nuclear new built,

of which Hungary expected to issue

a construction licence for a new

NPP in 2021. Regardless of massive

investment in the VRE resources all

across the EU, nuclear energy

remains by far the largest (26.7 % in

2019) single source of low-carbon

energy in the EU, ahead of hydro

(12.3 %), wind (13.3 %), and solar

(4.4 %).

As a possible contributor to the

carbon-neutral future, small modular

reactors (SMR) are receiving increased

attention. This is due to the

technological capability of nuclear

to deliver on-demand electricity,

coupled with a promise for great

simplification and related cost reduction

while applying industrial manufacturing

and construction technologies

at a factory rather than on site.

The SMRs are expected to address the

biggest obstacle for large nuclear

power plants: long construction

periods causing high capital costs.

Active licensing activities with sites

elected are underway in USA and

Canada. Several EU countries expressed

interest and as per news

bulletins, some including Estonia and

Poland started the negotiations with

potential suppliers of SMRs.

One of the typical complaints

regarding nuclear power is that it is

unsafe. To the wider public, when

considering with wide media coverage

and public interest related with any

nuclear accidents, and in particular

Chernobyl and Fukushima, such a

perception is understandable. However,

the fact of the matter is that no

one died from the radioactivity

released during Fukushima accident

(and as per UNSECAR report released

on 21st March 2021 “Radiation-linked

increases in cancer rates not expected

to be seen”). As per multiple

studies undertaken on the Chernobyl

accident and its consequences,

apart from several dozens of first

re sponders who died shortly after the

accident, there was a very limited

number of deaths caused by the radioactive

release. To put safety in the


Energy Policy, Economy and Law

A Role for Nuclear in the Future Dutch Energy Mix ı Bojan Tomic and Mario van der Borst

atw Vol. 66 (2021) | Issue 3 ı May


| Figure 1

Fatalities per TW of electricity generated for various sources.

perspective it is useful to assess the

fatalities per unit of generated energy

from various sources of electricity.

The fatalities caused by the nuclear

industry in Figure 1 reflect the GEN II

nuclear plants. Integral to the GEN III

and SMR reactors is the fundamental

design requirement of a strict limit to

any radiological release in a case of

accident. GEN III nuclear plants as

well as most SMRs are designed to be

“inherently safe”, meaning minimisation

of probability of accidents and

exclusion of off-site consequences

even in cases where a hypothetical

accident is to occur. Deployment of

such reactors would enable the construction

also in highly populated

countries, without concerns of the

population in the vicinity of a plant.

This applies even more to future GEN

IV reactors, where innovative and/or

revolutionary concepts might be

expected to lead to fully inherently

safe designs.

With that consideration, the notion

of nuclear not being safe does not pass

the scientific scrutiny. The energy that

could have been produced in nuclear

plants in Germany and instead was

produced by burning coal, lignite and

gas, affected the population and even

much more the climate (in 2018

German CO 2 emission per capita was

almost double of that in France or the

UK) not just in Germany but also in

the neighbouring countries.

Another criticism of nuclear power

is that it generates radioactive waste

that will remain dangerous for

millions of years to come. While

notionally true, it is also well known

and often ignored that the amount

of waste that remain dangerous for

extended period of time is extremely

small. Every other source of energy,

even VREs generates waste that

is dangerous to people and the

environment and would need to be

safely isolated, in quantities that are

(much) larger than the radioactive

waste generated in nuclear plants.

Important advances have been

achieved in the management of longlived

high-level radioactive waste.

Disposal in special canisters in geologically

stable layers in the deep underground

is inter nationally regarded

as a safe solution. Pragmaticallygoverned

countries, in particular the

EU Member states in Scandinavia,

implemented solutions for long-lived

waste that guarantees no effect to the

public and environment for much

longer periods that the humankind

exist on the Earth. It is useful to put

that in the perspective of currently

non-recyclable PV panels, or ever

increasing needs for exotic material

including rare earth, cadmium or

lithium, mining and processing of

which leave enormous impact on

the environment and its residues

entering the water supply affecting

the world’s population today. Furthermore,

unlike any other sources of

electricity, nuclear has from the very

beginning been planned to require

plant operators to make a provision

for decommissioning and for disposing

of any waste, thus these costs

are ‘ internalised’ as part of operating

costs. No other source of electricity in

the use today fully operates on such a


Societal costs of nuclear

Every source of electricity (or indeed

practically any other human activity)

has external impact that are not fully

reflected in the price, but which

society as a whole must bear. The best

example is the cost of emissions,

which may (and in reality already is)

cause damage to those who are

not related nor benefitting from the

activities. In the case of electricity

generation, the external costs of

interest are those related with three

components: emissions of CO 2 and

resulting climate change; damage/

impact such as on health and crops

associated with air, water or environmental

pollutants and other nonenvironmental

social costs.

External costs to the society from

the operation of nuclear power could

assumed to be negligible as there are

no emissions from the operation, and

the cost of management of waste

and decommissioning are internalised,

meaning included in the price.

Nevertheless, one might argue that a

serious accident causing damage

which is beyond the insurance limit

might become the societal costs. However,

for modern nuclear plants the

probability of such an accident is

extremely low and societal costs might

be expected not to exist for the Gen III

or inherently safe SMRs.

Electricity generation from fossil

fuels is not regulated in the same way,

and therefore the operators of thermal

power plants do not to internalise the

costs of greenhouse gas emission or of

releases in the atmosphere. In some

countries this is being addressed

through the CO 2 pricing. For VREs the

impact of the decommissioning and

waste management are not even

known, effectively making the future

societal cost.

Externalities of electricity production

are not limited to environmental

and health related impact, but may be

related with macro-economic, policy

or strategic factors not reflected in

market prices, such as security of

supply, cost stability and broad economic

impacts including employment.

Although those externalities generally

have not been subjected to systematic

assessment and comparison, some

qualitative analysis established high

advantage for nuclear as compared

with any other sources of electricity

on the majority of the parameters of


One further aspect for consideration

is in relation to the social impact

is the land utilisation. For this aspect,

the extremely high energy density of

nuclear (up to about a 1000 times) is a

great benefit compared to VREs. Due

to its low energy density, VREs require

lots of space. This is particularly

relevant for solar PVs, where the

installations are competing with land

available for agriculture and/or

encroaching the preserved nature,

and for onshore wind, where increased

opposition due to noise (on

Energy Policy, Economy and Law

A Role for Nuclear in the Future Dutch Energy Mix ı Bojan Tomic and Mario van der Borst

atw Vol. 66 (2021) | Issue 3 ı May

| Figure 2

The cost breakdown for Hinkley point C NPP.

shorter distance), drop shadow and

intrusions into natural settings is

becoming omnipresent.

Especially in densely populated

parts of Europe, such as the Netherlands,

enormous needs for space for

some of the technologies is becoming

increasingly a limiting factor in the

deployment. Further to this, the

disturbance of the landscape complains

are on the raise everywhere.

Although the “NIMBY” phenomena

affects any intervention, a much

higher energy density of nuclear

plants, the number of people affected

is only a fraction of those affected by

the low energy density VREs.

The cost of nuclear power

Often raised drawback for nuclear

power is that it is just “too expensive”.

Clearly, judging from the headline

numbers, e.g. the price of two large

GEN III nuclear units under construction

at Hinkley point in the UK is

above 24 billion Euros, or multiple

costs increases for similar units in

France (Flamanville 3) or Finland

(Olkilouto 3), the cost are very high.

Furthermore, many were astonished

with so called” strike price” for the

electricity from Hinkley point C being

94 GBP per MWhr when comparing

that with currently traded price of

about 50 to 60 GBP MWhr. However,

the comparison with the strike price of

about 140 GBP per MWhr for nondispatchable

offshore wind sources provides

a bit of perspective. To assess the

cost of nuclear it is important to understand

its background. The cost comparison

with other sources using the

“levelized cost of electricity” (LCOE)

provide interesting insights.

The construction of a nuclear plant

is a large and extremely complex

undertaking. While at the time of the

most intensive deployment of nuclear

plants in late seventies and eighties of

the last century, typical construction

period was in the order of 5 or so years.

| Figure 3

Cost of nuclear electricity in relation with WACC.

With fewer nuclear plants being

built nowadays, the construction duration

extended dramatically, beyond

15 years and counting for the EPR

reactors in Finland and France. Given

the high costs of a plant itself, just the

cost of deployed capital over such a

long period significantly contributes to

the overall cost. How ever, this is not

unique to nuclear plants. Other large

and complex infrastructure projects

experienced similar extension of the

construction periods and resulting

effects on the costs, e.g. an airport

(BER, a factor of 3 cost increase) or a

railway (Crossrail, factor of 3.5 cost

increase and counting). The difference

to those is in the financing costs.

The cost of capital

Where the nuclear plants are really

penalised, and which is the dominant

cause of their high price, is the costs

of the capital. While infrastructure

projects such as BER and Crossrail

attract the capital with very low costs,

due to a perceived risk related to

nuclear projects, the cost of capital

encompasses a risk premium. In

the costs profile of new nuclear the

majority is indeed the costs of capital,

i.e. interest and risk premium. For

Hinkley point C, about 65 % of the

total cost of the plant is associated

with interest payment.

It is obvious that with the cost of

capital as it is in the EU today (zero or

negative interest rates), an investment

model where two thirds of the cost is

to cover the interest is not sustainable.

With the weighted cost of the capital

(WACC) in the range of 4 %, simular

to what is used in VRE projects,

nuclear becomes fully cost com petitive

with other sources of carbon free


The system cost

Apart from the costs of investment

(construction) and operating costs

(fuel, operation, maintenance) various

| Figure 4

The contributors to cost of electricity, comparison between

nuclear, solar and wind.

energy technologies would have

specific costs related to the integration

into the electricity supply system. The

system costs typically include the

balancing costs (deviations from the

planned production and extra cost for

investment in reserves), the profile

cost (technology dependant, i.e.

anti- cyclicals able to achieve higher

prices) and the grid cost (extra cost of


Energy Policy, Economy and Law

A Role for Nuclear in the Future Dutch Energy Mix ı Bojan Tomic and Mario van der Borst

atw Vol. 66 (2021) | Issue 3 ı May


expanding the grid). The system costs

are highly dependent on the configuration

of the electrical system – the

energy mix. The system costs is

what differentiate between reliably

dispatchable energy sources being

able to supply agreed electricity to the

grid and non-dispatchable ones, being

dependant on external influences like

weather and therefore requiring

backups. For the VREs, the system

costs are also dramatically increasing

with the penetration, while dispatchable

technologies might be credited

with system benefits due to being able

to vary their outputs to support system


The further point of attention is the

electric potential (in installed MW)

that is needed to guarantee the supply

of electricity in dispatched MWh. This

is best explained by comparing solar

and nuclear. Because of the capacity

factor of about 10 % for solar and

90 % for nuclear, the installed capacity

for solar to generate the same

amount of electricity needs to be

9 times larger. The LCOE cost calculation

takes this into the account only as

far as the expected production of

electricity from different sources is

concerned (i.e. capacity factor). However,

the grid costs and in particular

the balancing and profile costs to

assure reliable supply of electricity,

are (much) higher for VRE, and

dramatically increasing with the

higher penetration. The system costs

strongly depends on the geography

i.e. whether large hydro is available.

Typical studies addressing the system

costs always take into the account a

certain proportion of hydraulic plants,

which is not the case in countries such

as the Netherlands.

Another important consideration is

that the deployment of a large share of

variable-electricity generating sources

with (nearly) zero marginal cost has a

profound impact on the functioning of

electricity markets and on the operation

of the generating capacity. In the

short term, reduced load factors (the

compression effect) and lower prices

| Figure 5

The relation of system cost to the penetration of VREs.

affect the economics of all dispatchable

generators. Above certain level of

penetration of VRE and at specific

weather conditions, there would be

no other generators on the market,

leading to a necessity of shutting

down some of the VRE producers. At

that time the implicit promise (i.e. the

state guarantee) that all electricity

that would be generated by VREs will

be taken by the grid and delivered to

the consumers suddenly disappears,

further increasing system cost but

also the LCOE due to lower overall


The system costs for the dispatchable

sources such as nuclear or coal/

gas are very small, in the order of

2 Euro/MWh. With a low penetration

of VRE, the system costs remain small,

as there are enough reserves to

balance the grid when VREs are not

generating. With an increased penetration

of VRE, and in particular above

about 50 %, the system costs become a

dominant contributor, as documented

in the research of the IEA in the

Figure 5.

The decarbonation of electricity

supply with VRE only leads to the

situation of both very high costs (due

to electric potential, needs for grid

development, etc.) AND accepting

regular blackouts as there will be

periods when none of the VREs would

generate electricity. Availability of

VREs is internally closely related, i.e.

non redundant: doubling the amount

of PV panels will not add to overnight

supply; all windmills would stand still

when there is no wind.

The studies analysing VRE role in

the electric supply often significantly

underestimate system cost by projecting

upwards from the current situation

where there is 10-20 % penetration.

Sometimes the “low” system

costs are justified with the assumption

that electricity will be unavailable for

certain amount of time, which is very

likely not acceptable to today’s society.

Furthermore, typically advertised

“low cost of VRE” often exclude the

grid connection cost, which in a case

of offshore wind becoming a dominant

contributor. On the contrary,

nuclear is constantly dispatchable,

able to balance the grid and its investment

costs already include the grid


It should be highlighted that some

nuclear plants are now being approved

to operate for 80 years, while the wind

generators and solar panels have projected

lifetime up to a maximum of

25 years (with discernible degradation

over the lifetime for solar PV).

Typically, after about 25 years, the

investment in a nuclear plant is

already paid off. For VRE, this is

exactly the time when the new investment

cycle is needed.

The LCOE estimates for the

Netherlands for the year 2040

The key request by the Ministry of

Economic Affairs and Climate Policy

was to estimate the LCOE for several

electricity generation technologies

for the year 2040, on a comparable

basis specifically for the Netherlands.

The study considered the following

emission free sources of electricity:

p Large nuclear GEN-III plant

p Nuclear SMR

p Off-shore wind

p On-shore wind

p Large solar PV

p Hydrogen Power

To make this comparison meaningful

with expected higher (50 %) penetration

of VREs, the adjusted “LCOE*”

was calculated to include the system

effects, as defined by the OECD NEA.

A full utilisation was assumed for

all sources of electricity, meaning that

each source would be allowed to

deliver to the grid when it is capable to

deliver, independent of electricityexchange-market

or other prioritization

mechanisms. For the stability of

the electrical grid with the higher VRE

penetration rates, VRE units would

also be obliged to shut down or reduce

the output at certain moments, like

now is the case with the dispatchable

plants. This will result in the utilisation

rates being lower than 100 %. As

those are not driven only by economic

considerations, rather by political and

other issues, the Study did not elaborate

further on the expected utilisation

rate. The basis assumption for the

assessment is included in the list in

the following table.

The findings could be best illustrated

by the summary Figure 6.

The results are pretty obvious:

even limiting the VRE penetration rate

to 50 %, the system costs became so

dominant that the dispatchable sources

are visibly cheaper than the VREs.

Compared with the offshore wind,

onshore wind and solar PV, two

nuclear options remain cheaper when

realistic system costs are considered in

the LCOE*. The Hydrogen Round trip

is very costly. The expla nation is in the

low efficiency, between 25 % and

39 % for the electrolyser and the

turbine, meaning that 60 % to 75 % of

the energy is lost in the process. The

hydrogen storage is assumed to

be in the salt-caverns. When storage

Energy Policy, Economy and Law

A Role for Nuclear in the Future Dutch Energy Mix ı Bojan Tomic and Mario van der Borst

atw Vol. 66 (2021) | Issue 3 ı May

in high pressure casks is selected, the

LCOE* for this option could be 5-10

times higher.

As with any prediction for the

future in a dynamic and changing

environment, the point values might

be far off if the assumptions change.

All such estimations, and in particular

those that are addressing the more

distant future, could only be made on

the basis of a set of assumptions, covering

wide range of issues, from the

technology development to the cost of

financing and learning curves. While

the projections of the LCOE* are considered

the best estimate, it was highly

interesting to assess how those estimates

would be influenced by changes

in the assumptions and/or relevant

parameters. The Study undertook a

series of sensitivity analysis, covering

the following:

p Construction times (duration)

p Learning effects consideration

p Impact of the lifetime of a plant

p Utilisation rates of a plant

p Interest-rate (WACC) sensitivity

p System costs sensitivity

p Sensitivity cases for hydrogen


The results are depicted in the

Figure 7, indicating the effects of


The example sensitivity case for

the VRE penetration rate of 75 %

shows an interesting correlation. The

increased penetration of VREs from

about 50 % to about 75 % leads to

approximately doubling of the system

costs for every technology. However,

for the technologies with lower system

costs, this effect is barely visible while

for the non-dispatchable sources of

electricity it dominates, as in the

Figure 8.

ENCO report caused quite a

stir in the Dutch media and


The prevailing public opinion in the

Netherlands is that nuclear indeed

contributes to lowering the emissions,

but that the costs would be many

times higher than solar and wind

energy. Reference is often made to the

cost overruns of the new construction

projects in Finland and France. As a

result, enthusiasm for nuclear energy

decreased even among the most

interested parties.

The ENCO report made it clear that

nuclear energy can compete with

solar and wind energy in the future, if

the system costs are allocated to the

energy source causing those. This

message did not please the renewable

energy interests and many articles

General assumptions

LCOE assessment Nuclear VRE

WACC 7 % 4,3 % 4,3 %

| Table 1

The relation of system cost to the penetration of VREs.

appeared in the media contradicting

the Study conclusions. Most of the

articles lacked factual arguments and

attempts were made to discredit the

authors of the ENCO report.

The consultancy firm Kalavasta,

which had previously published a

report on the “Costs of Nuclear

Energy”, wrote a negative assessment

report, mainly focusing on the fact

that” system costs are not that high”.

The conclusion and arguments used

have been thoroughly refuted by the

Dutch journal Kernvisie.

Reflecting Kalvasta criticism of the

ENCO report, questions were asked in

the Dutch parliament. The Parliamentary

committee organised a round

table discussion on December 2 nd

2020 attended by the members of

the Parliament and a variety of

experts from energy companies,

NGOs, consultancies and universities.

Unsurprisingly, this discussion ended

in a draw.

In the meantime, EPZ, the operator

of the nuclear power plant Borssele,

announced that it is preparing the

extension of its lifetime after 2033

and consideration for the expansion

of Borssele site with two new large

nuclear power plants. Several Dutch

provinces, such as Zeeland and

Brabant, do not rule out nuclear

energy as a solution for achieving a

100 % CO 2 neutral economy by 2050.

On March 17 th the elections for the

Dutch parliament took place. Nuclear

energy was one of the major discussion

topics during the campaign,

including the argument that there is

not sufficient space in the Netherlands

to rely on wind and solar energy

for decarbonisation. The opponents

claiming that nuclear energy is too

expensive. The political parties that

believe in a role for nuclear energy to

tackle the climate problem represent

the majority in the new Dutch

| Figure 6

LCOE* for the decarbonised generation for the Netherlands in 2040.

| Figure 7

The results of sensitivity analysis on the LCOE*.



Technical Lifetime (years) 60 25 20, electrolysers limiting

Depreciation period technical lifetime technical lifetime technical lifetime

Utilisation factor 100 % 100 % 50 %

Decommissioning costs

Waste costs

15 % of capital costs,

discounted at 3 %

Spent fuel dis posal and

storage, decomm. waste

included in decomm. costs

and operational waste in

O&M costs

5% of capital costs,

discounted at 3 %

Decommissioning waste

included in decomm.

costs and operational

waste in O&M costs

5% of capital costs,

discounted at 3 %

Decommissioning. waste

included in decomm.

costs and operational

waste in O&M costs

Construction time (years) 7 0,5 – 1,5 3, CCGT limiting

| Figure 8

The results of sensitivity analysis on the LCOE*.


Energy Policy, Economy and Law

A Role for Nuclear in the Future Dutch Energy Mix ı Bojan Tomic and Mario van der Borst

atw Vol. 66 (2021) | Issue 3 ı May


parliament (80 out of 150 seats). It is

expected that the nuclear option will

be the topic for the Dutch political

discussions for the coming years.

From financial standpoint it is

recognized that system costs are

the discriminating factor between

nuclear and the VRE. Numerous

institutes, including PBL, TNO but

also Berenschot/Kalavasta, involved

in the development of the Dutch

energy scenario studies all consider

system costs in their analysis. However,

the system costs as projected for

VRE are (by far) too optimistic and

systema tically fail to consider obvious

uncertainties. The extrapolation from

the present situation to the one where

VREs predominate is obviously impossible,

because in the present world

the VRE caused system costs are

absorbed by the still-available margins

in the electrical system. Some studies

consider arrangements to moderate

system cost including smart grids,

load rejection, car-loading systems

and decentralised generation enable

short transport trajectories. All these

solutions have their limitations and

many are not established and their

technical merits and general acceptance

is uncertain. Furthermore, zero

curtailment (100 % utilisation) is

assumed for the VRE, and 50 % to

70 % curtailment for nuclear. With

higher VRE penetration this becomes

impossible and furthermore it obviously

does not establish a level playing

field, where all CO 2 free generators

should have the same priority to the



The outcome of the Study for the

Netherlands lead to some interesting

insights. When the system costs are

properly accounted for, two nuclear

options are markedly cheaper than

the offshore wind and significantly

cheaper than photovoltaic. This is

even before other (positive) externalities

are considered, e.g. the lifetime

of nuclear plants being 60 or

even 80 years, while the VREs at best

last for 25 years, the spatial impact of

nuclear is a minuscule fraction of that

for the VREs, or that the cost of

nuclear already include provisions for

decommissioning and safe disposals

of all of its waste.

The positive vision on future

developments is affecting all technologies,

though mainly the offshore

wind and nuclear SMR. For large

nuclear significant saving could be

achieved by reducing the duration

of the construction; it is however

uncertain whether nuclear industry

would be able to erect a NPP in Europe

in less than 7 years. A much more

dramatic impact is observed with the

reduction of the capital costs for a

nuclear plant. When the WACC is

reduced from 7 % to 4,3 %, the

resulting decrease of LCOE* is around

25 %. With some EU governments

being able to borrow at negative rates,

low WACC for nuclear by implementing

risk- sharing instruments becomes

a pretty logical con sideration.

When the design lifetime of nuclear

plant is being extended from 60 to

80 years, the impact of this change on

LCOE* appears low. This is because of

the devaluation of money, the impact

of the last 20 years on the LCOE* in

relation to the full lifetime is not that

significant (due to the constant value


The LCOE* of all electricity generation

sources is driven by capital costs.

All sources have roughly the same

dependence on the utilisation, as all

need to operate to generate income.

The impact from 100 % to 60 % is

moderate. Below 60 %, the LCOE*

increases fast.

The LCOE* of Hydrogen Round

trip units is extremely high, especially

affected by lower utilisation factor of

electrolysers. At the UF of 20 %, a

typical utilisation factor of a “Peaker”

unit, the LCOE* will increase to above

700 €/MWh.

Nuclear power emits no greenhouse

gases. The complete nuclear

power supply chain, from uranium

mining to waste disposal, including

the construction and operation, is

estimated to emit only 2–6 grams of

CO 2 per kilowatt-hour generated. This

is less than even wind and solar, and

up to two orders of magnitude fossil

fuels. Nuclear should not be viewed as

being in competition with “renewable”

sources of energy, such as wind or

solar. As the reduction of carbon emissions

becoming a top priority, both

nuclear and renewable sources have

both roles to play.

Possibly the most relevant finding

from the Study is that with the

level playing field for all non-carbon

emitting sources for electricity,

nuclear is fully competitive and even

dominates other sources in several

areas. The current situation where

VREs are effectively subsidized by

having guaranteed income (i.e. all

VRE generation is taken by the grid

and paid for at a predetermined price,

regardless of the need for such

electricity) will became impossible

with higher penetration of VREs, as

some will have to periodically shut

down. This, together with system

costs, further undermines the competitiveness

of VREs. On the contrary,

nuclear with its guaranteed dispatchability

and reliability of supply, when

financed with capital costs that are

prevailing in the markets today,

becomes the most affordable non

carbon emitting source of electricity.


Bojan Tomic

Principal Consultant

ENCO, Vienna, Austria


Bojan Tomic has more than 35 years experience in the

nuclear sector internationally. He started his career as

the designer of nuclear plant safety systems at

Combustion engineering in USA. He was a First officer

at the IAEA’s Nuclear safety division, with responsibilities

for probabilistic safety assessments and operational

safety. He continued his career as a consultant

with ENCO, advising clients on various aspects of

utilisation of nuclear and radiological technologies

worldwide. He was engaged in numerous modelling

and analytical studies, including due diligence

assessment for new nuclear units. Bojan has been

involved with many nuclear safety initiatives at the EU

level, most notably in the EU Post Fukushima Stress

test activities, where he led the peer review team

assessing national stress tests in several countries

including Germany. More recently he was on the

Board of ENSREG’s Topical peer review on Ageing

management of NPPs. Mr Tomic is a member of the

Borssele Benchmark committee.

Mario van der Borst

Principal Consultant


Mario van der Borst started his career in R&D at TNO

in the Netherlands. In 1984 he entered the Nuclear

Industry. He specialized in Thermo-Hydraulics and

Probabilistic Safety Assessments. He was responsible

for major back-fitting and O&M projects at the NPP

Borssele. From 2003 till 2010 he was the Technical

Director of this plant. In 2010 he entered the RWE

New Build Team to be responsible for Technology,

Authorization and Regulation. At that time RWE was

involved in NNB projects in the UK, Netherlands,

Romania and Bulgaria. He is president of the Dutch

Nuclear society. At the moment he is principal


Energy Policy, Economy and Law

A Role for Nuclear in the Future Dutch Energy Mix ı Bojan Tomic and Mario van der Borst

atw Vol. 66 (2021) | Issue 3 ı May

BREST-OD-300 – Demonstration

of Natural Safety Technologies

Vadim Lemehov and Valeriy Rachkov

Introduction The article discusses the need to update the strategy for the development of nuclear power, various

approaches to the development of large-scale nuclear power. The current state of fast reactor technologies development

is examined through the example of the BREST-OD-300 reactor plant and the closed nuclear fuel cycle (CNFC) in Russia

with highlighting the main problems. The problems of choosing solutions for fast reactors and organization of the

nuclear fuel cycle are discussed within the article as well.

Evaluation of prospects for the

development of the nuclear power

industry in Russia and other countries

shows the presence of two trends [1]:

1. Focusing on the development of

the nuclear power industry on the

basis of the existing and improved

types of thermal reactors with an

open nuclear fuel cycle that use

mainly U-235. This also includes

possibilities of using a limited additional

fuel resource in the form of

mixed oxide uranium-plutonium

fuel (MOX-fuel). It is obtained by

single recycling of spent nuclear

fuel (SNF) from these reactors,

separation of accumu lated plutonium,

and mixing it with depleted

uranium. Despite a long history,

the share of MOX fuel in the world’s

nuclear fuel pro duction for thermal

reactors has never exceeded

5 %, and its production at some

plants ( Belgium, UK) is ceasing.

2. Focusing on the development of the

closed nuclear fuel cycle (NFC)

with the introduction of reactors

ensuring simple nuclear fuel conversion

or nuclear fuel breeding

(BR ≥ 1). These could be conventional

fast neutron reactors (FNRs)

or the light water hard spectrum

reactors (LWRs) previously discussed

in the 1970s and newly

proposed in the United States and

Russia. Nuclear fuel breeding

provides full-scale involvement of

natural uranium (with 99.3 %

U-238) in the plutonium- uranium

breeder producing fissionable

plutonium from U-238 and fissionable

U-233 from natural Th-232 in

the breeder reactor.

The first approach involves evergrowing

quantities of natural uranium

that is used less than 1 % energy-wise,

and the amount of accumulated SNF

constantly in creases. In the conditions

of modern energy markets, this

approach is recognized as economically

justified. A concept of

further development of this approach

has spread in the Unites States, which

has the largest nuclear power industry

in the world, and has been promoted

by leading nuclear power plant (NPP)

designers in emerging countries,

where nuclear power engineering is in

progress. According to American

experts, the world‘s known uranium

resources make it possible to stay on

this track for a long time.

It is obvious that large-scale nuclear

power engineering can be implemented

only under the second

approach. But development strategies

under this approach are conceptually

different in different countries,

depending on the expected role of

fast-neutron reactor (FNR) in the

structure of the nuclear power industry.

There are three strategies for the

formation of large-scale nuclear power

engineering, which can be conditionally

distinguished: [1].

“AS USUAL” Strategy. The United

States in the foreseeable future will

rely on thermal light water reactors

(LWRs) with the open NFC, and

provision is made for the transition to

SNF reprocessing from LWR (being

accumulated in a tem porary storage

facility for 100 years) in order to

reduce the amount of high level waste

(HLW) subject to final disposal by

means of burning of minor actinides

(MA) from HLW in an FNR. At the

same time, FNRs themselves are

considered as noncompetitive energy

generators and possible “cleaners” for

the dominant LWRs. For such FNRs, a

breeding ratio (BR < 1) is adopted,

and their NFCs remain open, since it

requires a constant external (not from

the NFC) makeup by fissile nuclides. A

possibility of using FNRs with BR ~ 1

and BR > 1 is under consideration,

but their mission remains fundamentally

the same.

Closed NFC with thermal reactors

(TRs). France and Japan, which

do not have their own uranium deposits,

have traditionally built their development

strategies providing for the

transition from LWRs with the open

NFC to sodium-cooled FNRs with the

closed NFC and a BR much larger

than 1, ensuring LWR makeup fuel

supply. A similar strategy was considered

and has still been proposed bv a

team of specialists in Russia.

Closed NFC with FNR. The

Russian Strategy Guidelines formulated

in the “Strategy for the Development

of Russia’s Nuclear Power Industry

in the First Half of the 21 st Century”

[2] and worked out in detail in [3] is

based on the concept of large-scale

nuclear power engineering, which can

be used to solve its main tasks by

means of FNRs of moderate power

rate without surplus plutonium produc

tion remaining in the structure of

previously built NPPs with thermal

reactors. In this case, the complete

inner plutonium breeding (IBR » 1)

with dense nitride fuel of equilibrium

composition is important.

Scenarios for the formation of

FNRs with the closed NFC should be

based on the actually established

structure of the nuclear power industry.

In this regard, it is important to

understand the difference between

temporary two-component nuclear

power engineering ensuring a gradual

transition from thermal reactors to

FNRs, and basic two-component

nuclear power engineering, where

thermal reactors play a key role and

fast breeder reactors only feed them

with fuel and burn HLW.

The idea of the basic twocomponent

nuclear energetics was

developed in the second half of the

last century under the influence of the

following factors:

p Development of uranium enriched

thermal reactors for military

purposes and their further modernization

for the civilian power


p Understanding of the necessity of

FNRs for the development of

nuclear power industry;

p Economic uncompetitiveness of

fast reactors reactors built in

dif ferent countries with their

specific features determined by the



Operation and New Build

BREST-OD-300 – Demonstration of Natural Safety Technologies ı Vadim Lemehov and Valeriy Rachkov

atw Vol. 66 (2021) | Issue 3 ı May



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ISSN 1431-5254

require ments of a large BR: high power density, use of a

sodium coolant, pro duction of weapon-grade plutonium

in the blanket.

With the development of the uranium enrichment technology,

thermal reactors became the basis of modern

nuclear power engineering, and, for more expensive FNRs

with a large BR, they could be used for thermal reactors’

makeup fuel supply (with plutonium produced by FNRs)

in case of cheap natural uranium depletion. In such a

two-component nuclear power industry, a large-scale SNF

and MOX fuel circulation is required between fast and

thermal reactors and centralized nuclear fuel recycling


The “Strategy for the Development of Russia’s Nuclear

Power Industry in the First Half of the 21 st Century” [1]

considers two-component nuclear power as a Stage of a

gradual tran sition from thermal to fast neutron reactors,

which forms the basis of the future large-scale power


The main large-scale development factors of the nuclear

power industry in Russia and the world remain safety and

economic competitiveness with other types of energy

generation. Russia’s nuclear power processing datum

surface on the basis water-water energetic reactors (VVER)

reactors is sufficient for the scale of NPP construction and

volume of exports forecasted by the ES-2030. [4] However,

its long- term strategic potential is limited by the inconsistency

of a safety level with requirements for large-scale

nuclear power engineering, limited natural uranium

resources, SNF accumulation, and falling competitiveness

due to increased safety measures.

The “Strategy for the Development of Russia’s Nuclear

Power Industry in the First Half of the 21 st Century” [2]

defined main conditions for natural safety of a large-scale

nuclear power industry:

p Elimination of accidents requiring evacuation, and

especially resettlement of the population and withdrawal

of significant areas from economic use;

p Effective use of energy potential of the extracted fuel

raw materials;

p Circulation of nuclear materials in the fuel cycle

without significant violation of the natural radiation

balance 1 ;

p Technological support of the nonproliferation of

nuclear weapons;

p Ensuring the competitiveness of nuclear power

engineering in comparison with other types of energy


The abandonment of the thermal reactor plutonium

makeup from the SNF solves the problem of choosing

between a large or small FNR BR in favor of the inner BR

(IBR) close to l. It should be noted again that the smallscale

nuclear energy system (NES) component is an

imperative associated with acceptable safety of the largescale

nuclear power engineer ing, while the choice between

the hybrid NFC (with the enriched uranium makeup) and

a closed NFC (with the plutonium makeup from the FNR

SNF) is a matter of economic feasibility.

Sometimes fears are expressed that in the case of a FNR

BR close to one, it is impossible to increase the power of the

nuclear power plant in a short time (if necessary). But,

firstly, today even the most optimistic forecasts do not

1 Preservation of the natural radiation balance assumes that, after a certain

historically short period of time, the total radioactivity and radiotoxicity of the

waste generated as a result of the NPP operation, reprocessing of irradiated fuel

and land-buried waste will not exceed the total radioactivity and radiotoxicity of

the uranium isotopes extracted from the earth’s crust to supply NPPs with fuel.

Operation and New Build

BREST-OD-300 – Demonstration of Natural Safety Technologies ı Vadim Lemehov and Valeriy Rachkov

atw Vol. 66 (2021) | Issue 3 ı May

discern such a scenario for

the development of nuclear power.

Secondly, if such a scenario turns out

to be in demand, then, without going

beyond the natural safety, it can be

implemented by quickly putting in any

rationally required amount of FNR

capacity with fuel from enriched

uranium or using a blanket, the

presence of which in the countries

of the “nuclear club” meets nonproliferation


At present, it can be considered

theoretically proven and computationally

experimentally substantiated

that such three additional

requirements for FNR, as IBR close

to 1 [5], lead coolant [6] and dense

nitride uranium-plutonium fuel

(MNIT-fuel) [7], make it possible to

significantly increase the safety

level of FNR that meet these requirements,

in com parison with FNR

with IBR, significantly less than

one (larger only when using a

blanket), with sodium coolant and

MOX fuel mastered in Russia. Thus,

for a large-scale component of

nuclear power, an FNR with a IBR

close to unity, with lead coolant

and dense uranium- plutonium fuel

is required.

1. In connection...

with the requirement to increase the

level of safety, in relation to the reactor

installations of NPPs, six main

technical solutions can be distinguished

that ensure the satisfaction

of the natural safety requirements of

large-scale nuclear power, which are

demonstrated in the BREST-OD-300

reactor plant: The equilibrium active

zone of FNR

The equilibrium FNR core allows

minimizing the reactivity margin for

nuclear fuel burnout and virtually

eliminating instantaneous neutron

acceleration (Figure 1).

2. Dense fuel

Among the fundamental properties

of dense fuel, three play a significant

role in terms of influencing the basic

characteristics of the active zones and

safety: density, thermal conductivity,

and the specific amount of scattering

light elements (oxygen, carbon, and


A higher fuel density and a smaller

number of light elements contributes

to an increase in the reproduction

coefficient in the reactor core (IBR)

and the integral BR for the reactor

plant (RP). Special unique properties

are acquired by active zones with the

so-called “equilibrium” fuel, in which

| Figure 1

Reactivity reserve for the campaign of the BREST-OD-300.

the burning of the fissile material is

completely compensated by its reproduction.

Dense fuel allows realizing an

equilibrium core (Figure 2) with a IBR

of about one (Table 1), that provide:

p complete reproduction of fissile

nuclides, which is a sufficient

con dition for the practical use of

the energy resource U-238;

p work without a uranium blanket,

which eliminates the production of

low-background radiation with a

quality close to weapons-grade;

p the absence of the need to separate

plutonium from SNF and the

possibility of using technologies

without separating uranium and

plutonium, which together with

the previous advantage provide

technological support for the nonproliferation


p minimization of the burnout

reactivity margin, which reduces

the maximum reactivity margin of

the reactor vessel and increases the

nuclear safety of the reactor vessel;

p unique stability of fuel rods and

fuel assemblies heat release during

their operation.

Currently, more than 1,500 fuel rods

have been tested in the BOR-60 and

BN-600 rector plants, including up to

a burn-up depth of 9.3 % t. a.

3. Wide core grid

The wide grid of the core allows

having a level of natural circulation

sufficient to remove the residual heat

and reduce the power consumption

for pumping the coolant.

4. Integrated layout of the

reactor plant

The integrated layout of the reactor

plant (Figure 3) allows excluding the

loss of core cooling.

All primary circuit equipment

required for organizing the circulation

circuit and transferring energy to the

heat conversion circuit is located in a

single reactor block.

5. Heavy liquid metal coolant

The choice of lead as a coolant for the

BREST-OD-300 reactor plant stems


p the presence of a well-founded

lead coolant technology, i.e. a set

of measures and means to ensure

the required quality of the coolant

and the cleanliness of the primary

circuit during operation;

p low potential energy associated

with possible chemical reactions

involving lead;

p negligible moderating ability of

lead nuclei, which, on the one

hand, eliminates the problem of

the positive void effect of coolant

reactivity, and on the other hand,

| Figure 2

Cartogram a.z. reactor plant BREST-OD-300.

Number of fuel assemblies in the core 169

Core height, mm 1,100

MNIT fuel density, g/cm 3 12.3

Full load of MNIT fuel, t 20.8

Max. burn-up depth in the discharged fuel

(at the initial stage), % t. a.

Average ST temperature at the inlet/outlet

of the core, °C

Average energy intensity of a.z., MWth/m 3 140

Maximum linear power over the core, W/cm 420

| Table 1

Index a.z. reactor plant BREST-OD-300.

9.3 (6.0)


Reproduction rate (blanket is missing) 1.05


Operation and New Build

BREST-OD-300 – Demonstration of Natural Safety Technologies ı Vadim Lemehov and Valeriy Rachkov

atw Vol. 66 (2021) | Issue 3 ı May


| Figure 3

The view of BREST-OD-300 reactor plant.

allows the use of a wide lattice in

the core, thereby providing an

effective mode of natural circulation

of the coolant in the core with

a simultaneous decrease in coolant

velocity (almost twice as compared

with sodium coolants in a sodiumcooled

fast breeder reactor (BNreactor)

reactor) and hydraulic

resistance of the circulation loop

and, as a consequence, with a reduction

in the power consumption

for pumping the coolant;

p low availability of lead nuclei in

the neutron flux, which makes it

possible to switch from a vessel

structure to a pool structure,

charac terized by a high heat capacity,

and place the equipment in a

concrete shaft lined with steel

or cast iron compatible with lead,

with a decrease in the cost of a

reactor installation and an increase

in reactor safety in transient and

emergency processes due to the

thermal inertia of the circuit;

p high boiling point (~ 1745 °C) of

the lead coolant, which excludes

accidents associated with the crisis

of heat exchange (in the reactor,

due to the higher pressure in the

core, the boiling point of lead can

reach 2300 °C).

The above benefits are illustrated in

Figures 4 and 5.

The figures are given for the worst

conditions of heat removal from the

reactor core – complete blackout.

There is a shutdown of four reactor

coolant pumps (RCPs) and a cessation

of feed water supply during operation

at the initial nominal power. The

removal of the residual energy release

is carried out by two of the four

emergency core cooling systems

(ECCSs) loops (the failure of the other

two ECCS loops and the failure of the

ECCS is postulated).

Result: for all standardized

radionuclides, emissions into the

atmo sphere do not reach the control

level per day.

6. Using ambient air

as an aftercooler

Use of atmospheric air as a final cooler

without intermediate circuits in the

case of natural circulation removal of

residual heat in a high-power reactor

plant (Figure 6).

In addition to the safety requirements

for nuclear power plants, there

are a number of requirements for

closed NFC technologies, which

are implemented at the Industrial

pilot facility with a power complex

with the BREST OD-300 reactor, a

plant for the production of nuclear

fuel from the products of reprocessing

of spent nuclear fuel and a

plant for repro cessing spent nuclear


p low-waste reprocessing spent

nuclear fuel from FNR;

p involvement of SNF reprocessing

products from thermal reactors

into the nuclear reactor fuel cycle;

p reduction of the duration the spent

nuclear fuel spends on the nuclear

reactor before its reprocessing to

1 – 2 years;

p ensuring the radiation balance

between the extracted fuel raw

materials and the buried radioactive

waste (RW);

p technological support for the

nonproliferation regime.

| Figure 4

Change in power (1) and flow through the reactor (2).

| Figure 5

Temperature change of fuel (1) and fuel element cladding (2).

Operation and New Build

BREST-OD-300 – Demonstration of Natural Safety Technologies ı Vadim Lemehov and Valeriy Rachkov

atw Vol. 66 (2021) | Issue 3 ı May

| Figure 6

ECCS plan.

In connection with the requirements

for the technologies of the closed

NFC, three technical solutions can

be distinguished:

p “dry” reprocessing of spent

nuclear fuel from FNR to reduce

the duration of spent nuclear fuel

holding before reprocessing and to

exclude the separation of pure

plutonium during reprocessing;

p transmutation of minor actinides

in FNR to ensure a balance

between the extracted fuel raw

material and the disposed radioactive


p abandonment of the blanket in

FNR to exclude the production of

weapon-grade plutonium (when

exporting technologies).

The question remaining is competitiveness

of NPPs in general and on the

basis of FNR in particular. Obviously,

without norms and standards corresponding

with the new technological

nuclear power platform the solution

of this question is difficult. The first

approach to the answer about the feasibility

of competitive CNFC power

engineering based on fast neutron reactors

will be given by conceptual projects

of industrial power facilities with

reactor plants BN-1200 and BR-1200.

balance between the extracted fuel

raw material and buried RAW) are

preferable for the large-scale

nuclear power engineering in


3. To prove the advantages of reactors

with lead coolant, a pilot demonstration

power complex is being

created at the site of JSC Siberian

Chemical Combine (SKhK).

4. Answers to the questions related to

the industrial production and

application of MNIT fuel for the

IPF on the BN-1200 and BR-1200

basis can be given only in case of its

pilot application in the BREST-

OD-300 reactor plant of the industrial

pilot facility.

5. Answers to the questions related to

the industrial reprocessing of

MNIT-SNF for the isotope production

facilities (IPF) can be given

only in the operation of the

processing module on the pilot

demonstration facility.

6. Technological support of the nonproliferation

regime in the export

version of natural safety technologies

is not a complete solution to

the nonproliferation problem but

only an important addition to

institutional tools of its solution.

7. For a radical solution to the CO 2

problem, it is possible to develop a

large-scale nuclear power industry

by the end of this century, which

means a gradual transition to FNRs

with closed NFC in the nearest


8. The main requirement for the

development of the nuclear power

industry is its competitiveness,

primarily with the generation

based on organic fuels and with

renewable energy sources in terms

of exports. Preliminary calculations

for industrial power complexes

with fast reactors operating

in a closed fuel cycle show the

possibility of achieving parity with

other types of generation.






Reactor Plant

Radioactive Waste

Spent Nuclear Fuel

Thermal Reactor

Water-Water Energetic Reactor


[1] New Technological Platform for the National Nuclear Energy

Strategy Development / Adamov E.O., Rachkov V.I. // Russian

Academy of Sciences Bulletin.

Energy. – 2017.– No. 2. – P. 3-12.

[2] Development Strategy of the Russian Nuclear Power Industry

for the First Half of the XXI Century. Main Provisions, Minatom

Rossii, Moscow, 2000. – 26 p.

[3] E. O. Adamov, A. V. Dzhalavyan, A. V. Lopatkin,

N. A. Molokanov, E. V. Murav’ev, V. V. Orlov, S. G. Kalyakin,

V. I. Rachkov, V. M. Troyanov, E. N. Avrorin, V. B. Ivanov, and

R. M. Aleksakhin, Conceptual Provisions of the Development

Strategy of the Russian Nuclear Power Industry in Prospect up

to 2100 - NIKIET, Moscow, 2012. – 61 p.

[4] Energy strategy of Russia for the period up to 2030

[approved. by order of the Government of the Russian

Federation of November 13, 2009 No. 1715-r].

[5] E. O. Adamov, et al., White Book of Nuclear Power

Engineering – NIKIET, Moscow, 2001. – 496 p.

[6] E. O. Adamov, V. I. Rachkov, et al., “Choice of coolant for

nuclear power plant with inherent safety,” Izv. Ross. Akad.

Nauk Energ., No. 6, 3 − 14, 2015

[7] E. O. Adamov, L. M. Zabud’ko, V. I. Matveev, V. I. Rachkov, V.

M. Troyanov, Yu. S. Khomyakov, and V. N. Leonov,

“ Comparative study of advantages and disadvantages of the

use of metal and mixed nitride uranium- plutonium fuel in fast

reactors,” Izv. Ross. Akad. Nauk., Energ., No. 2, 3 − 15, 2015.


Vadim Lemehov

Chief Designer and

Technical Committee

member of the Proryv



Valeriy Rachkov

Research and Development

Chief Scientific

Officer of the Proryv

Project* as well as

Technical Committee




1. A large-scale element of twocomponent

nuclear power engineering,

i.e. a closed nuclear fuel

cycle FNR, requires an FNR with

the inner breeding rate close to 1

with a lead coolant and dense

uranium- plutonium fuel to ensure

the necessary safety level.

2. Low-waste “dry” SNF reprocessing

(mainly to reduce a duration of the

SNF conditioning before its reprocessing)

and minor actinide transmutation

(to ensure a radiation


BN Sodium-Cooled Fast Breeder Reactor

BR Breeding Ratio

CFC Closed fuel cycle

ECCS Emergency Core Cooling Systems

FNR Fast-Neutron Reactor

HLW High Level Waste

IBR Inner Breeding Ratio

IPF Isotope Production Facilities

LWR Light Water Reactor

MA Minor Actinides

MNIT Mixed Uranium-Plutonium Nitride Fuel

NES Nuclear energy system

NFC Nuclear Fuel Cycle

NPP Nuclear Power Plant

RCP Reactor Coolant Pump

* Proryv project

is implemented

by Rosatom

Operation and New Build

BREST-OD-300 – Demonstration of Natural Safety Technologies ı Vadim Lemehov and Valeriy Rachkov

atw Vol. 66 (2021) | Issue 3 ı May



Nuclear Innovation Alliance (NIA)

The Nuclear Innovation Alliance (NIA) is focused on championing cuttingedge

solutions to the climate challenges of this century. NIA is a non- partisan,

non-profit, “think-and-do” tank working to ensure advanced nuclear energy

can be a part of the climate solution. By engaging with policymakers,

industry, and other stakeholders, NIA works on licensing modernization,

policy development, and industry commercialization to bring economicallycompetitive,

zero-carbon energy to U.S. and global markets. Advanced

nuclear energy technologies face economic, political, and social obstacles

to successful development, demonstration, and commercialization. NIA

believes these obstacles can be overcome by encouraging public and private

investment in advanced nuclear innovation at a scale adequate to drive

meaningful innovation, and by building strong public trust in emerging

technologies through collaboration among industry, government, labor, and

civil society.

NIA approaches its education and engagement efforts

thoughtfully, by producing technically-informed analysis

and policy recommendations for policymakers, investors,

and members of the public. It informs licensing

moder nization efforts at the U.S. Nuclear Regulatory

Com mission (NRC), educates policymakers in the

legislative and executive branches, and promotes

commercialization through collaboration with industry.

NIA also promotes entrepreneurialism through its annual

Nuclear Innovation Bootcamp.

“NIA’s highest objective is to help achieve the conditions

for advanced nuclear energy success. We believe

advanced nuclear energy is key to making substantial

and identifiable progress in climate protection. NIA is an

advocacy hub for advanced nuclear energy policy in the

United States, and is building a durable and sustainable

organization with an expanding base of support,” says

Judi Greenwald, NIA Executive Director.

Currently, NIA is primarily funded through charitable

grants and philanthropic donations from climateconcerned

individuals and foundations. With its strong

policy research base, NIA regularly works with policymakers

and fellow NGOs, including The Breakthrough

Institute, Clean Air Task Force, ClearPath, Good Energy

Collective, and Third Way. The organization also reaches

out into the broader nuclear energy ecosystem by

actively engaging with advanced nuclear developers

and investors, as well as universities, national laboratories,

and other technical research institutions. More

recently, NIA has also begun to work collaboratively with

stakeholders outside of the nuclear sector, including

environmentalists, other clean energy industries, labor,

and energy consumers.


NIA was created in 2015 after the Clean Air Task Force

spun off its advanced nuclear program under Dr. Ashley

Finan into a separate organization. Under Dr. Finan’s

leadership, NIA quickly emerged as a leader in analysis,

stakeholder convening, and advocacy for advanced

reactors. Through a mix of coordination, reports, and

Congressional testimony, NIA played a major role in the

development and passage of two major pieces of


The Nuclear Ecosystem and the NIA’s Role in Innovation

P The Nuclear Energy Innovation and Modernization

Act (NEIMA), which required reforms at the NRC to

facilitate the licensing of advanced reactors, including

the development of a risk-informed, performancebased,

technology-inclusive pathway.

P The Nuclear Energy Innovation and Capabilities Act

(NEICA), to support U.S. Department of Energy

research activities and to ensure national research

assets facilitate private innovation.

At a Glance

Nuclear Innovation Alliance (NIA)

atw Vol. 66 (2021) | Issue 3 ı May

Beyond these two major successes, the NIA also worked

on nuclear export control reform, nuclear energy geopolitics,

and other priority areas for the industry.

In 2019, Dr. Finan departed NIA to head Idaho National

Laboratory’s newly formed Nuclear Reactor Innovation

Center, an institution created by NEICA. In 2020, Judi

Greenwald was selected to replace Dr. Finan, bringing an

extensive background in energy and environmental

policy leadership in Washington, DC. Recently, NIA has

grown its staff as the pace of licensing modernization

and commercialization for advanced reactors grows.

From one employee at its founding, NIA is set to reach

four employees in summer 2021, supported by fellows

and outside consultants.

Building on its success in helping pass NEIMA, NIA is

pursuing an ambitious research agenda to inform

licensing modernization at the NRC. NIA continues to

monitor and support NRC efforts to develop Part 53, a

performance-based licensing pathway for advanced

reactors. NIA is also conducting research on potential

NRC fee reforms to reduce barriers to reactor innovation,

identifying ways to shorten the duration of NRC reviews,

and evaluating how to make U.S. licensing compatible

with international approaches.

Beyond its regulatory work, NIA engages extensively

with policymakers as they endeavor to enact and

implement new laws to drive nuclear innovation.




NIA is overseen by its Board of Directors, and consults

with its Industry Innovation Leadership Council and

Advisory Committee, to ensure its approach to achieving

conditions for success encompasses a broad range of

interests and perspectives, including investors, government

leadership, and the public.

NIA’s Industry Council is a forum for advanced reactor

developers to discuss innovation challenges and opportunities.

Reformed in early 2021, the Council informs the

NIA’s strategy and activities but does not set NIA policy.

The current members of the Council include leading

advanced reactor developers in the U.S.:

P BWX Technologies, Inc.

P Framatome,

P GE Hitachi

P General Atomics

P Holtec

P Kairos

P NuScale

P Oklo

P Terrapower

P Terrestrial Energy USA

P Ultra Safe Nuclear Corporation

P Westinghouse

P X-Energy

Ongoing Activities

Today, NIA is engaged in many activities to catalyze the

development of advanced nuclear energy. In February,

NIA and the Partnership for Global Security released a

joint strategy for U.S. leadership on commercialization of

advanced reactors. The report, titled “U.S. Advanced

Nuclear Energy Strategy for Domestic Prosperity, Climate

Protection, National Security, and Global Leadership,”

details a whole-of-society approach; with collaboration

between government, industry, civil society, and other

nations that can bring advanced reactors to market to

reduce global emissions, provide domestic jobs, and

support national security. The Strategy and other reports

by NIA are available on the NIA website.

Nuclear Innovation Bootcamp

NIA is a proud sponsor and organizing partner of the

Nuclear Innovation Bootcamp, an annual workshop that

introduces select students and early career professionals

to advanced nuclear energy and the 21st century energy

landscape. Over the span of two weeks, participants

engage in multi-disciplinary classes and workshops

delivered by a broad array of presenters, all while

developing group ventures that are ultimately pitched to

industry leaders. Past Bootcamps have incorporated a

diverse range of topics including technology, marketing,

policy, and public relations. Bootcamp alumni are active

across industry, academia, and the policy space.

In 2016, the first Nuclear Innovation Bootcamp was held.

The program convened twenty-five students from

around the world at UC Berkeley, where the students

developed and pitched nuclear start-up concepts to a

panel of judges. Using lessons learned from the inaugural

edition, the program format was enhanced and

remained at UC Berkeley for the following two years. In

2019, the Bootcamp, “Atoms in Action,” was hosted at

the OECD Nuclear Energy Agency in Paris, France.

Twenty- seven students and young professionals from

10 countries and 4 continents took part that year, the

Bootcamp’s first edition in Europe. While there, they

drew upon experience from the established French

nuclear industry and learned about exciting developments

taking place in the European advanced nuclear


In light of the COVID-19 pandemic, the 2020 Bootcamp’s

programming was abbreviated, moved online, and

opened to past alumni. Due to ongoing public health

concerns and travel restrictions, the NIA and other

cooperating organizations are looking to build on the

success of the 2020 online experience and develop an

equally engaging program for 2021.




At a Glance

Nuclear Innovation Alliance (NIA)

atw Vol. 66 (2021) | Issue 3 ı May



Safety-related Residual Heat Removal

Chains of German Technology Pressure

Water Reactors (Light and Heavy Water)

Franz Stuhlmüller and Rafael Macián-Juan

Introduction The Nuclear Power Plants (NPPs) with Pressure Water Reactor for enriched fuel (PLWR, Pressurized

Light Water Reactor) and for natural uranium (PHWR, Pressurized Heavy Water Reactor), developed in Germany, are

largely identical in their basic design. However, there is a striking difference in the scope of the main reactor systems.

While in PLWR these only consist of Reactor and Reactor Coolant System including Pressurizer and Pressurizer Relief

Tank, in PHWR the Moderator System is added. In power operation of a PLWR, the entire thermal reactor power is

transferred to the water/steam cycle via the Steam Generators. In PHWR, on the other hand, part of the power has to be

removed - at a lower temperature level - from the moderator, which is spatially separated from the main reactor coolant

within the Reactor Pressure Vessel, but is kept at the same pressure via function-related compensating openings. This

portion of power is used to preheat the feed water before it enters the Steam Generators. The Moderator System

installed for this purpose can also be used in a second function as the inner link in the Residual Heat Removal Chain

(RHRC) for cooling the Reactor after it has been switched off. In PLWR the analog system is operated exclusively for the

removal of residual heat from the Reactor and, if necessary, the Fuel Pool. In the following, the development steps of the

RHRC of both NPP lines are shown and the main differences between both NPP-types in this regard are explained by

comparing the most recently erected plants, DWR 1300 MW (KONVOI) and Atucha 2.

*In the case of sump

operation after loss of

coolant, the extraction

does not take place

from the reactor system,

but from the floor

(sump) of the Reactor

Building Interior. With

the PLWR, this is

achieved by switching

to a separate suction

line in the intake to the

Residual Heat Removal

Pump. The PHWR uses

the Safety Injection

Pump for this – possibly

in parallel operation

with the Moderator

Pump – which thus

becomes part of the

RHRC. In the further

explanations and

figures these RHRC

special variants are not


Residual Heat Removal Chain,

Structure and Terms

Figure 1 shows the basic structure of

the RHRC using the example of a plant

with four cooling lines, as is the case

with DWR 1300 MW and Atucha 2

(CNA 2). The figure also illustrates the

terms “system” (or “RHR link”), “subsystem”,

“RHR line” (resp. “redundancy”)

and “RHR Chain”. While a

“system” contains the entirety of all

“subsystems” of an RHR link (horizontal

unit), each “RHR line” is made up

of three contiguous subsystems, from

heat source to heat sink (vertical unit).

All RHR lines together form the “RHR

Chain” (although in normal usage a

chain is understood to mean what is

referred to here as a line).






Residual Heat





Safety Component

Cooling System/

RHR Intermediate

Cooling System

Secured Service

Cooling Water




3 4





3 4



Heat Sink



3 4


The RHRC thus consists of three

procedural systems, namely

p a circulation system for reactor

coolant or moderator, connected

to the reactor cooling loops or

directly to the Reactor Pressure


p an intermediate cooling system,

which takes heat from it in heat

exchangers, and

p transfers it in other heat exchangers

via the Secured Service

Cooling Water System to the external

heat sink. “Secured” expresses

that the system – like the entire

RHRC – has a fail-safe design and

that its electrical units can be

operated via the NPPs Emergency

Power Supply, if necessary.



3 4


Residual Heat Removal Chain






Residual Heat Removal Pump/

Moderator Pump

Residual Heat Exchanger/

Moderator Cooler

Component Cooling Pump/

RHR Intermediate Cooling Pump

Component Cooling

Heat Exchanger/

RHR Intermediate Cooling

Heat Exchanger

Secured Service Cooling

Water Pump

| Figure 1

Residual Heat Removal from the Reactor; Definition of “System” (or “RHR link”), “Sub-System”,

“RHR Line” and “RHR Chain”.

Temporal Development

of the RHRC

The development steps up to the latest

versions of the RHRC for PLWR and

PHWR go hand in hand with the

chronological growth of the unit sizes

of both NPP variants from the second

half of the 1960s to the end of the

1980s (Figure 2).

Starting with MZFR (multi- purpose

research reactor Karlsruhe) as a prototype

NPP of a PHWR and KWO

(Obrigheim nuclear power plant) as a

PLWR demonstration plant, the unit

power outputs increased with almost

constant gradients,

p at the PLWR version via KKS ( Stade

nuclear power plant) to the KWB-A

plant (Biblis nuclear power plant,

Unit A). This was followed by a

consolidation phase with the

construction of several (1200 to)

1300 MWel class NPPs (before

the step towards an EPR size of

≥ 1600 MWel was taken),

p at the PHWR with a significantly

flatter course via Atucha 1 (CNA 1)

to CNA 2 plant as the last NPP of

this type to date.

Hereinafter, the RHRC concepts of all

of the above power plants (without

EPR) are shown in their original

version. Later retrofittings, e.g. as

adaptation measures to tightened

safety regulations are not considered.

In the first plants – both PLWR and

PHWR – the single-line concept or

multi-line in meshed construction was

common for the systems of the RHRC.

Here e. g. cross-connections between

individual subsystems of an RHR link

Environment and Safety

Safety-related Residual Heat Removal Chains of German Technology Pressure Water Reactors (Light and Heavy Water) ı Franz Stuhlmüller and Rafael Macián-Juan

atw Vol. 66 (2021) | Issue 3 ı May

| Figure 2

Temporal Development of unit net power of german-type PLWR and PHWR plants.

are established, via which, if necessary,

a standby pump can optionally be

connected to several circuits. However,

this design pre supposes that failure of

passive system parts, such as piping,

does not have to be assumed. The

extension of scenarios to be controlled,

in particular the postulate that in the

event of an accident, in addition to

the maintenance or repair of a component,

a single failure also occurs on

any system part, led to transition to

the completely line-separated concept

with three or four RHR-lines for the

RHRC, depending on the unit size. This

change took place step by step for both

types of NPP, with the line separation

developing from the inner to the outer

link of the cooling chain, i.e. starting

with the Moderator System (PHWR)

resp. the Residual Heat Removal

System (PLWR) up to the Secured

Service Cooling Water System.

The following descriptions are

exclusively in the present form, also

for the plants that have already been


NPPs with Pressurized Light

Water Reactor

Immediately after switching off a

PLWR power plant, cooling of the

reactor system basically takes place

via the Steam Generators (exception:

loss of coolant accidents above certain

leak sizes). At the time, when cooling

is taken over by the RHRC, pressure

and temperature of the reactor cooling

circuit have already been reduced to

such an extent, that the design values

for the Residual Heat Removal System

can be kept significantly lower than

those of the reactor system. The heat

to be removed has sunk so far, that an

intermediate cooling system, designed

for low temperature and low pressure,

can be used on the secondary side of

the Residual Heat Exchanger. This

intermediate cooling system (called

“Component Cooling System”) supplies

further safety- related and operational

cooling points in parallel to the

Residual Heat Exchanger. If the RHRC

has a multi-line structure at least up to

and including the Component Cooling

System, then two component cooling

subsystems are designed so that –

alternating – they can supply cooling

water to all of the operational cooling

consumers (e.g. of Reactor Coolant

Pumps and nuclear auxiliary systems)

in addition to their line- associated

safety-related cooling points.

NPP Obrigheim (KWO),

283 MWel

The RHRC is formed from one line,

i. e. each RHR link from one circuit.

The Residual Heat Removal System

here includes two Residual Heat






4 7







| Figure 3

KWO, Reactor Coolant System and RHR Chain.

Removal Pumps connected in parallel

and two Residual Heat Exchangers,

both of which are integrated on their

secondary side in the single component

cooling circuit [1].

Special features of KWO are:

p The additional use of the Residual

Heat Exchangers as low-pressure

coolers within the Volume Control

System (not shown in Figure 3),

p Two Emergency Secured Service

Cooling Water Pumps (in addition

to the regular two Secured Service

Cooling Water Pumps).

NPP Stade (KKS), 630 MWel

The Residual Heat Removal System as

the inner link of the RHRC is carried

out in two subsystems, but is still

mesh-designed with one Residual

Heat Exchanger und two Residual

Heat Removal Pumps each [2], [3],

[4]. The other two RHR links consist –

like at KWO – of only one circulation

system each, but with special features.

These are:

p Three Component Cooling Pumps,

p Three Component Cooling Heat

Exchangers connected in parallel

(which were probably activated as


p Two additional Emergency Component

Cooling Pumps (not shown

in Figure 4),

p Three Service Cooling Water


NPP Biblis Unit A (KWB-A),

1150 MWel

With KWB-A, already in 1975 the

RHRC took the shape, which subsequently

– with a few safety-relevant

additions – became the standard and

Main Steam System

Reactor Coolant System

Residual Heat

Removal System

Component Cooling


Secured Service

Cooling Water System

SG Steam Generator

RCP Reactor Coolant Pump









Residual Heat Removal Pumps

Residual Heat Exchangers

Component Cooling Pump(s)

Component Cooling

Heat Exchanger

Secured Service

Cooling Water Pumps

Emergency Secured

Service Cooling Water Pumps

Further Component Cooling

Water Consumers

Further Secured Service

Cooling Water Consumers


Environment and Safety

Safety-related Residual Heat Removal Chains of German Technology Pressure Water Reactors (Light and Heavy Water) ı Franz Stuhlmüller and Rafael Macián-Juan

atw Vol. 66 (2021) | Issue 3 ı May













has since been used for all following

PLWR plants [5], [6]. The number of

RHR lines usually, but not necessarily,

corresponds to the number of reactor

cooling loops. For this size of units

(and also for the EPR concept

(≥ 1600 MWel) four Steam Generators

and thus four reactor cooling

loops are required for heat transfer to

the water/steam cycle in power operation.

Accordingly, the RHRC also

consists of four independent RHR

lines with a heat transfer capacity of

50 % each, based on the design case.







| Figure 4

KKS, Reactor Coolant System and RHR Chain.


Main Steam System

Reactor Coolant System

Residual Heat

Removal System

Component Cooling


Secured Service

Cooling Water System

SG Steam Generator

RCP Reactor Coolant Pump







Residual Heat Removal Pumps

Residual Heat Exchangers

Component Cooling Pumps

Component Cooling

Heat Exchangers

Secured Service

Cooling Water Pumps

Further Component Cooling

Water Consumers

(Note: Even for plants with only three

reactor cooling loops, this “one to

one” assignment of loop and line

number can be obtained without

violating the safety philo sophy (repair

and simultaneously single-failure)

when the heat transfer capacity of

each line is increased to 100 %.) In

Figure 5, the two inner component

cooling circuits are designed for the

alternating supply of operational

component points. For this purpose,

in addition to the regular Component

Cooling Pump, a second pump is

connected in parallel, operated in case

of a very high cooling water demand.

NPPs of DWR 1300 MW class

The increasing safety-related requirements,

set down e. g. in the “RSK

Guidelines for Pressurized Water

Reactors” [7] and in “Safety Regulations

of the KTA” [8], [9], in


p elevated awareness of the fuel pool

inventory as a source of activity,


p the inclusion of “civilizationrelated

external impacts” (aircraft

crash, explosion pressure waves,

third part influences) as cases to be


led to important extensions for the

system technology of the steam

generator feed as well as for the RHRC


With the Emergency Feed Water

System, a possibility of short- and

medium-term heat removal from the

Reactor Coolant System via the Steam

Generators was created, independent

of the Feed Water Tank and the regular

Emergency Power Supply. For the

subsequent long-term cooling via the

so-called Emergency Cooling Chain

(ECC) in this two of the four RHR

lines, whose residual heat removal

circuits contain a Fuel Pool Cooling


p an Emergency Component Cooling

Pump within the Safety Component

Cooling System*, and

p an Emergency Secured Service

Cooling Water Pump in the Secured

Service Cooling Water System.


Cooling points

Reactor Reactor

Building Building

Interior Annulus





Main Steam System

Reactor Coolant System

Residual Heat

Removal System

Component Cooling

System (safety-related part)

Component Cooling

System (operational part)

Secured Service

Cooling Water System

Steam Generator

RCP Reactor Coolant Pump







Residual Heat Removal Pumps

Residual Heat Exchangers

Component Cooling Pumps

Component Cooling

Heat Exchangers

Secured Service

Cooling Water Pumps

Further Component Cooling

Water Consumers

7 Further Secured Service

Cooling Water Consumers

| Figure 5

KWB-A, Reactor Coolant System and RHR Chain.

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atw Vol. 66 (2021) | Issue 3 ı May

Emergency Feed

Water System


8 9 10










are installed in parallel to the existing


The Fuel Pool Cooling Pumps

themselves act as “Emergency Residual

Heat Removal Pumps” as part of

the Residual Heat Removal System in

this case. If required, all this pumps

are supplied with power via the

Emergency Generators, which – after

the Emergency Feed Water Pumps

have been disconnected – are driven

by the Emergency Diesel Engines.

For the fuel pool cooling, in

addition to the two RHR lines that

include the Fuel Pool Cooling Pumps,

there is also another fuel pool cooling

circuit whose single cooler is supplied

by the Operation Component Cooling


NPPs with Pressurized Heavy

Water Reactor

The function of the Moderator System

in power operation of the plant

requires identical pressure and

temperature design values as for the

Reactor Coolant System itself. However,

this also opens up the possibility

– by switching over valves inside

the Moderator System and with an

appropriate design of the RHR Intermediate

Cooling System as the middle

link of the RHRC – to take over the

cooling of the reactor immediately

after shut down, even without additional

Steam Generator feed. This

option has not yet been implemented

for the MZFR as the first PHWR plant.

Only CNA 1 and CNA 2 are equipped

with a high pressure/high temperature

designed RHRC and are therefore

independent of the function of the

main heat sink (steam turbine condenser)

for cooling down the plant






after all shut-down occasions to be


Multi-purpose research reactor

Karlsruhe (MZFR), 50 MWel

The shutdown concept of the MZFR

basically corresponds to that of PLWR

plants, with priority on the Steam

Generators [11]. Only when this –

below a certain coolant temperature –

is no longer thermodynamically

possible, switch over to RHRC operation

has to be performed for further

cooling of the plant. Moderator temperature

and heat to be removed at

this time are already so low that the












3. Fuel Pool

7 4 7 Cooler 7 4 7 4






2 2



6 6 Reactor






3a 3


3 3


Emergency Feed

Water System

8 9 10


Cooling points

Reactor Reactor

Building Auxiliary

Interior Building

| Figure 6

DWR 1300 MW, Reactor Coolant System and RHR Chain.

Emergency Feed

Water System

10 9 8














5 7

| Figure 7

MZFR, Reactor Coolant System and RHR Chain.

Emergency Feed

Water System

9 8



Moderator Cooler on its secondary

side can be operated with inlet

temperatures, which are accepted by

the other cooling points of the

Component Cooling System without

boiling at its outlet; even at the slight

overpressure with which the Component

cooling System is operated.

A special feature of the MZFR-

RHRC is that the operating pressure in

the Secured Service Cooling Water is

higher than in the system. In the event

of a heat tube leak in the Component

Cooling Heat Exchanger, transition

of possibly radioactive contaminated

water to the environment is thereby


Main Steam System

Reactor Coolant System

Residual Heat

Removal System

Safety Component

Cooling System

Secured Service

Cooling Water System

SG Steam Generator

RCP Reactor Coolant Pump

1 Residual Heat Removal Pumps

1a Fuel Pool Cooling Pumps

2 Residual Heat Exchangers

3 Component Cooling Pumps

3a Emergency Component

Cooling Pumps


Operation Component

Cooling System

Component Cooling

Heat Exchangers


Main Steam System

Reactor Coolant System

Moderator System

Component Cooling


Secured Service

Cooling Water System

Steam Generator

RCP Reactor Coolant Pump

1 Moderator Pumps

2 Moderator Coolers

3 Component Cooling Pump(s)

4 Component Cooling

Heat Exchanger

5 Secured Service

Cooling Water Pumps

6 Further Component Cooling

Water Consumers

7 Further Secured Service

Cooling Water Consumers

5 Secured Service

Cooling Water Pumps

5a Emergency Secured Service

Cooling Water Pumps


Safety-related Cooling Points

7 Secured Intermediate Coolers

8 Emergency Feed Water Pumps

9 Emergency Generators

10 Emergency Diesel Engines

11 Demineralized

Water Pool

*With introduction of the

new “Power Plant

Labeling System (KKS)”

in 1976 the Component

Cooling System was,

without any technical

impact, split into “Safety

Component Cooling

System” and “Operation

Component Cooling

System”. The former

includes the Component

Cooling Pumps,

the Component Cooling

Heat Exchangers as

well as the supply of all

cooling points that are

relevant for operation

of the RHRC. The latter

only consists of the

connected pipe network,

which distributes

and collects the cooling

water flows to consumers

of nuclear

operating systems

inside Reactor- and

Reactor Auxiliary



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Safety-related Residual Heat Removal Chains of German Technology Pressure Water Reactors (Light and Heavy Water) ı Franz Stuhlmüller and Rafael Macián-Juan

atw Vol. 66 (2021) | Issue 3 ı May








2 1

1 2 Feed Water



4 4


| Figure 8

CNA 1, Reactor Coolant System and RHR Chain.


avoided, but pollution of the demineralized

water in the component

cooling circuit may happen instead. In

subsequent plants, the pressure gradation

was implemented consistently

from the heat source (high) to the

heat sink (low).

NPP Atucha 1 (CNA 1),

319 MWel

The Moderator System consists of two

completely separate loops, each of

which assigned to a circuit of the RHR

Intermediate Cooling System [12],

[13], [14]. Deviating from MZFR, the

task of this system is to be able to take


Main Steam System SG Steam Generator

Reactor Coolant System RCP Reactor Coolant Pump

1 Moderator Pumps

Moderator System

2 Moderator Coolers

RHR Intermediate

3 RHR Intermediate

Cooling System

Cooling Pumps

Component Cooling

4 RHR Intermediate


Cooling Heat Exchanger

Secured Service

Cooling Water System




5 Secured Service

Cooling Water Pumps

6 Component

Cooling Pumps

7 Component Cooling

Heat Exchanger


Component Cooling

Water Consumers

9 Fuel Pool Coolers

over the reactor cooling already

shortly after shut down of the Reactor.

The asso ciated temperature and

pressure values ​in the system preclude

the use of the Component Cooling

System for heat removal; this is

designed to only supply all other

safety- related and the operational

cooling points as a single circuit

without redundancy. It is fitted out

with two Component Cooling Heat

Exchangers and Component Cooling

Pumps of full capacity each. The

RHR Intermediate Cooling System is

equipped with a third RHR Intermediate

Cooling Pump. In the event of

failure of one of the two regular

pumps this additional pump takes

over the circulation in the affected

circuit. The return lines of the RHR

Intermediate Cooling Circuits cannot

be shut off to the area around the

Moderator Cooler flowed through by

the feed water during power operation,

so that the feed water pressure is

impressed on them in their standby

state. After the feed water lines at the

outlet of the Moderator Cooler have

been shut off and transition to the

RHRC cycle operation is completed,

the water balance in the RHR Intermediate

Cooling Circuits (absorption

of expansion water when heating up,

recovery of contraction water when

cooling down) can be carried out via

expansion tanks as well as discharges

to the Feed Water Tank on the one

hand, and feed from the tank or the

demineralized water pool by means of

system-associated pumps on the other


A line assignment has not yet

been made for the outer RHRC link,

the Secured Service Cooling Water

System. Three parallel Secured Service

Cooling Water Pumps can feed a

manifold, from which all inter coolers

as well as the Fuel Pool Coolers are


NPP Atucha 2 (CNA 2),

692 MWel

A clear line separation concept has

been implemented at CNA 2. Although

the plant only has two reactor cooling

circuits, the Moderator System and

the entire RHRC are constructed with

four lines, each of them having a

capacity of 50 % of the total power to

| Figure 9

CNA 2, Reactor Coolant System and RHR Chain.

RCP Reactor Coolant Pump

SG Steam Generator











Moderator Pumps

Moderator Coolers

RHR Intermediate Cooling Pumps

RHR Intermediate Cooling Heat Exchangers

Secured Service Cooling Water Pumps

Component Cooling Pumps

Component Cooling Heat Exchangers

Component Cooling Water Consumers

Fuel Pool Coolers

Secured Intermediate Coolers

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Safety-related Residual Heat Removal Chains of German Technology Pressure Water Reactors (Light and Heavy Water) ı Franz Stuhlmüller and Rafael Macián-Juan

atw Vol. 66 (2021) | Issue 3 ı May

be removed in the design case. Thus

the “repair + single-failure” criterion

for accidents is fulfilled. Not only the

RHR Intermediate Cooling System,

but also the Safety Component

Cooling System here consists of four

circuits, which supply the respective

associated consumers – i. e. pumps

and their motors – with cooling water.

The circuits of the two outer re dundancies

in Figure 9 can also be optionally

switched on to cooling points of

the fuel assembly transport devices

(not shown in Figure 9). One circuit

of the two inner redundancies serves

not only its safety-relevant consumers,

but also the Operation Component

Cooling System, the other one stands

by for that. The design of the RHR Intermediate

Cooling System enables –

if necessary – a takeover of heat transfer

from the Reactor Cooling System

after shut-down of the plant without

the aid of Steam Generator feed. To

achieve the maximum possible heat

removal capacity, the bypasses inside

the RHR Intermediate Cooling Circuit

around Moderator Cooler and RHR

Intermediate Cooling Heat Exchanger

must be closed. If it is necessary for

the RHRC to keep the Reactor Cooling

System at a desired temperature state

or to cool it down according to a

specified shutdown gradient, this is

done by opening/ closing the bypass

around the Moderator Cooler and

by controlling the flow rate through

the primary side of the RHR Intermediate

Cooling Heat Exchanger on

the one hand and the bypass around

the cooler on the other (Shutdown


An important modification compared

to CNA 1 is the handling of the

water balance in the RHR Intermediate

Cooling Circuits. Facilities

for absorbing expansion water and

re-feeding it when the circuit cools

down as well as replacing operational

medium losses (in the event of failure

of operational demineralized water

supply) are set up for each circuit

self-sufficient and spatially separated

from each other in the Reactor

Building Annulus.

Each of the four subsystems of the

Secured Service Cooling Water

System with one Secured Service

Cooling Water Pump each, supplies all

of the assigned heat exchangers in

parallel, that are

p one RHR Intermediate Cooling

Heat Exchanger,

p one Component Cooling Heat


p one Secured Intermediate Cooler,

(This heat exchanger removes the

Emergency Feed

Water System







heat loss from the line-assigned

Emergency Diesel Engine and the

Secured Chilled Water System,

which is absorbed in the so-called

Secured Closed Cooling Water


p One Fuel Pool Cooler (Each one of

the two coolers is connected to two

subsystems of the Secured Service

Cooling Water System; this is why

in Figure 9 and Figure 10 below –

only to illustrate the supplyability –

four pool coolers are drawn.)




6 6


Building 6





3a 3


3 3 3a

3. Fuel Pool

4 7 4 7 Cooler

7 4 7 4


Main Steam System

Reactor Coolant System




Residual Heat Removal System

Safety Component Cooling System





2 2

8 9 10 8 9 10

10 9 8

10 9 8



Emergency Feed

Water System



Cooling Points

Reactor Reactor

Building Auxiliary

Interior Building

Comparison DWR 1300 MW –

Atucha 2

By comparing the RHRC configurations

of the latest PLWR- and PHWR

plants in Figure 10 it is intended to

show at a glance their differences

in the type and scope of process

engineering equipment for the removal

of residual heat from the

reactor cooling system. Furthermore,

it is marked which resp. how many

subsystems/lines must be active

during power operation of the plant.



DWR 1300 MW

Emergency Feed

Water System





Operation Component Cooling System

Secured Service Cooling Water System

| Figure 10

DWR 1300 MW – CNA 2, Comparison of RHR Chains regarding their necessary use during power operation of the plant;

Explanation of Numbers: see Figures 6 and 9.


Emergency Feed

Water System





Environment and Safety

Safety-related Residual Heat Removal Chains of German Technology Pressure Water Reactors (Light and Heavy Water) ı Franz Stuhlmüller and Rafael Macián-Juan

atw Vol. 66 (2021) | Issue 3 ı May


DWR 1300 MW

Reactor SG




















Main Cooling







Steam Systems

Reactor Coolant System

Moderator System

Feedwater System

Main Condensate System

Main Cooling Water System

Steam Generator

Reactor Coolant Pump

FWT Feed Water Tank









High Pressure Turbine

Low Pressure Turbine

Moisture Separator

Moderator Pump

Moderator Cooler

Main Feedwater Pump

1 2



3 5

Main Cooling






Feedwater Heater

Main Condensate Pump


Feedwater Heater

| Figure 11

DWR 1300 MW – CNA 2, Comparison of Water/Steam Cycles (simplified).

In order to complete the comparison,

the water/steam cycle must

also be included. By using the

Moderator Cooler for preheating the

feed water, the PHWR – in this

regard – is considerably simplified in

comparison to the PLWR (Figure 11).

In addition to the High Pressure

Preheaters themselves, the steam

extraction points on the high- pressure

section of the Steam Turbine and the

connecting steam pipes are eliminated

for the PHWR.

The second above item determines

the number of pumps within the

RHRC that are to be operated continuously,

and thus also the electrical

auxiliary power demand as well as the

net efficiency.

In Figure 10 mean:

p Thick drawn subsystems and


Used in power operation

p Thin drawn subsystems and


Operation readiness

p Thin drawn heat exchanger edging,

but with thick drawn flow symbol:

Flow through its secondary side,

but without heat input

For DWR 1300 MW, the upper part

of Figure 10 shows the minimum

amount of subsystems to be operated.

It is assumed that

p the fuel pool cooling circuit

connected to the Operating Component

Cooling System is sufficient

to maintain the fuel pool water

under the desired temperature.

Otherwise, one of the outer RHR

lines would have to be operated

with a Fuel Pool Cooling Pump,

addi tionally or exclusively.

p operation of only one of the four

Secured Chilled Water Systems

(which are redundantly supplied

by the Secured Closed Cooling

Water Systems) is necessary and

therefore just one of the Secured

Intermediate Coolers (No. 7 in

Figure 6 and Figure 10 above) has

to be flowed through. If this is not

the case, then additional subsystems

of the Secured Service

Cooling Water System must be


With CNA 2, the constantly running

Moderator Pumps mean that their

cooling points – line-separated –

always have to be supplied with cooling

water via the Safety Component

Cooling System. Therefore, all its

subsystems as well as the entire

Secured Service Cooling Water S ystem

must continuously be operated. With

regard to the heat removal capacity,

actually only the line which is connected

to the Operation Com ponent

Cooling System with its permanent

heat input is utilized, fully or only


The part of the RHR Intermediate

Cooling System not flowed by feed

water is separated and in stand-by


In contrast to the DWR 1300 MW,

the fuel pool cooling in CNA 2 is

completely independent from the heat

removal via the RHRC. Here, the fuel

pool cooling circuits transfer the heat

to be removed directly to the Secured

Service Cooling Water.


Development of the Residual Heat

Removal Chain (RHRC) in NPPs with

Pressurized Water Reactors of german

design, from the prototype plant

MZFR (heavy water) and the

demonstration power plant KWO

(light water) to the last plants erected,

was carried out on three mutually

independent areas:

p PLWR and PHWR:

Increasing requirements concerning

plant-internal damage


The assumption of failing of passive

components and system parts

as well as the postulate of simultaneity

of “repair case and single

failure” led to the (step- by-step)

Environment and Safety

Safety-related Residual Heat Removal Chains of German Technology Pressure Water Reactors (Light and Heavy Water) ı Franz Stuhlmüller and Rafael Macián-Juan

atw Vol. 66 (2021) | Issue 3 ı May

P transition from the single-line

to the multi-line RHRC-design

with several functionally independent

redundancies of the

same heat transfer capacity. In

plants with four RHR lines – as

is the case with the DWR

1300 MW class as well as with

Atucha 2 – each of the lines has

to be equipped with a heat

removal capacity of 50 %, based

on the thermodynamic design

case of the entire RHRC.

P This goes hand in hand with

abandoning meshing technology

in which, for example, if

a pump fails, a reserve unit

can be switched to various

subsystems of an RHR link.

p PLWR – specific:

Measures for emergencies “civilization-related

external impacts”

For the first time after the occurrence

of accidents, in which it is no

longer possible to feed the Steam

Generators from the Feed Water

Tank, the Emergency Feed Water

System was created to remove the

residual heat via Steam Generators,

for the long-term range via

the Emergency Cooling Chain

(ECC) Chain, both of them operated

by self-sufficient diesel engines/

generators. According to the safety

requirements two Emergency

Cooling Lines of a thermal capacity

of 100 % each, with respect to the

max. power to be removed, are

sufficient. For this ECC, sub systems

of the middle link (Safety Component

Cooling System) and the

outer link (Secured Service

Cooling Water System) of the

existing RHRC are equipped with

additional, less powerful pumps –

parallel to the main pumps. By

using this two lines as ECC which

contain a Fuel Pool Cooling Pump

in their inner link, this aggregates

are also deployed as “emergency

residual heat removal pumps”.

Both the Reactor and the Fuel Pool

can thus be cooled via these lines.

p PHWR – specific :

Transition to a high-pressure/

high-temperature RHRC

The residual heat removal concept

of the MZFR as the first plant of this

type of NPPs is largely identical

with that from PLWR. In the first

time after Reactor shut-down

cooling is performed exclusively

via the secondary side (Steam

Generator) before the RHRC takes

over with the Moderator System

as the inner link. Only in the

sub sequent plants Atucha 1 and

Atucha 2 the fact has been utilized,

that with the Moderator System a

“ Residual Heat Removal System” is

available, which is similar to the

Reactor Cooling System regarding

its pressure/temperature design

values. By also designing the

middle RHR link, the RHR Intermediate

Cooling System, as highpressure/high-temperature


it was possible to create a divers

residual heat removal option for

the Steam Generators, with which

reactor cooling is possible from the

beginning – without further Steam

Generator feeding.


[1] Lepie, G., Martin, A.

“Aufbau der Gesamtanlage KWO”

Atomwirtschaft, December 1968

P. 596 – 606

[2] Kernkraftwerk Stade

“Tabelle: Wichtige Daten des Kernkraftwerks Stade”

Atomwirtschaft, November 1971

P. 586 – 590

[3] Müller, H., Stahlschmidt, H.

“Die Gesamtanlage des Kernkraftwerks Stade”

Atomwirtschaft, November 1971

P. 579 – 580

[4] Bruhn, H.

“Reaktorhilfs- und Nebenanlagen des KKS”

Atomwirtschaft, November 1971

P. 610 – 612

[5] Huttach, A., Putschögl, G., Ritter, M.

“Die Nuklearanlage des Kernkraftwerks Biblis”

Atomwirtschaft, August/September 1974

P. 420 – 430

[6] Bald, A., Brix, O.

“Die Dampfkraftanlage des Kernkraftwerks Biblis”

Atomwirtschaft, August/September 1974

P. 431 – 438

[7] “RSK-Leitlinien für Druckwasserreaktoren”

Original version (3 rd edition of October 14, 1981)

with amendments of November 15, 1996

[8] Sicherheitstechnische Regel des KTA

“KTA 3301, Nachwärmeabfuhrsysteme

für Leichtwasserreaktoren”

Version 2015-11

[9] Sicherheitstechnische Regel des KTA

“KTA 3303, Wärmeabfuhrsysteme für Brennelementlagerbecken

von Kernkraftwerken mit Leichtwasserreaktoren”

Version 2015-11

[10] Rieser, R., Brosche, D., Faber, P.

“Planung, Errichtung und Inbetriebnahme

des Konvoi-Leitprojektes Isar-2”

Atomwirtschaft, June 1988

P. 276 – 284

[11] Bald, A., Schamburger, R.

“Die Dampfkraftanlage”, from “MZFR Kernkraftwerk

mit Mehrzweck-D2O-Druckkesselreaktor in Karlsruhe”

Atomwirtschaft, July/August 1965

P. 363 – 368

[12] Frewer, H., Keller, W.

“Das 340-MW-Kernkraftwerk Atucha

mit Siemens-Natururan-Druckwasserreaktor”

Atomwirtschaft, July 1968

P. 350 – 358

[13] Herzog, G., Sauerwald, K.-J.

“Das Kernkraftwerk Atucha”

Changed reprint from ATOM und STROM, 15 th Year,

issue 4, April 1969

P. 53 – 63

[14] Hirmer, G., Seifert, W.

“Das Kernkraftwerk Atucha”

Elektrotechnische Zeitschrift,

Ausgabe A (ETZ-A), Band 90, (1969)

P. 509 – 513


Franz Stuhlmüller

External Scientific

Associate at the Chair of

Nuclear Technology at

the Technical University

of Munich



Franz Stuhlmüller studied Mechanical Engineering at

the Rudolf-Diesel-Polytechnikum in Augsburg as well

as Energy and Power Plant Technology at the Technical

University of Munich. He was employed at Kraftwerk

Union / Siemens AG in Erlangen in the field of nuclear

power plants as well as conventional power plant

technology. As a section manager he was responsible

for decay power calculation and design of nuclear

safety systems, conventionally for the development of

advanced coal-fired combined cycle power plants as

well as new emerging power generation technologies.

After he retired in 2007 he was a consultant during

completion of the Heavy Water Nuclear Power Plant

Atucha 2 in Argentina till 2015. Since 2016 Franz is an

External Scientific Associate at the Chair of Nuclear

Technology at the Technical University of Munich


Prof. Rafael

Macián-Juan, PhD

Head of the Chair

of Nuclear Technology

at the Technical

University of Munich



Prof. Rafael Macián-Juan has a Master of Science in

Energy Engineering from the Polytechnic University of

Valencia, Spain, as well as a Master of Science in

Nuclear Technology and holds an PhD in Nuclear

Technology by the Penn State University, USA. He is

the Head of the Chair of Nuclear Technology since

2007 at the Technical University of Munich (TUM).

Before joining TUM, he worked at the Paul Scherrer

Institute (PSI), Switzerland, where he carried out

research and development in reactor thermalhydraulics

and coupled neutronics, as well as safety

assessments of the Swiss nuclear power plants. His

current research interests include nuclear safety,

multi-physics and multiscale simulation codes,

uncertainty and sensitivity methods, experimental and

numerical thermal-hydraulics, and safety analysis and

development of future nuclear reactor designs. He is

currently also visiting professor at Harbin Engineering

University in China.


Environment and Safety

Safety-related Residual Heat Removal Chains of German Technology Pressure Water Reactors (Light and Heavy Water) ı Franz Stuhlmüller and Rafael Macián-Juan

atw Vol. 66 (2021) | Issue 3 ı May


IAEA Approach to Review the

Applicability of the Safety Standards

to Small Modular Reactors

Paula Calle Vives, Kristine Madden and Vesselina Ranguelova

Introduction A continuously increasing interest in nuclear power, and particularly in small modular reactor (SMR)

technologies, has been expressed over the past several years by numerous IAEA Member States particularly in

contributing to the mitigation of climate change. Today there are over seventy (70) SMR designs under development

according to the IAEA booklet Advances in Small Modular Reactor Technology Developments, a Supplement to IAEA

Advanced Reactors Information System (ARIS) [5]. While SMRs are typically designed to generate electric power up to

300 MW, many new designs are also designed for other heat production applications, such as district heating,

desalination and hydrogen production or a combination of the former.

SMRs present novel features and

innovative technologies, including

different types of coolant, nuclear fuel

and neutron spectrums and inherent

safety features. As for all reactors,

SMRs shall meet the objective of

ensuring the protection of people and

the environment from the harmful

effects of ionizing radiation. A key

element of meeting this objective

is demonstrating compliance with

fundamental safety principles and

safety requirements.

The IAEA safety standards reflect a

widely accepted extensive approach

to ensure nuclear safety, establishing

safety principles, requirements and

associated guidance. The IAEA safety

standards are Member States consensus

based documents that have

been developed in an iterative fashion

and capture wider aspects of legal,

regulatory, siting, design, construction,

commissioning, operation, decommissioning,

and release from

regulatory control of nuclear facilities

and radioactive waste management,

including disposal. Although the IAEA

safety standards are considered to

be technology neutral, they are influenced

by specific issues pertaining to

water cooled large reactors technology

as most of the experience and

knowledge in the Member States

contributing to the development of

safety standards is based predominantly

the existing technology.

In recent years, the IAEA has

undertaken various initiatives to

review the applicability of certain

safety standards to particular types of

SMRs. Until now, however, the IAEA

has not systematically assessed the

applicability of the IAEA safety

standards to all types of SMRs

through out their entire lifecycle.

Therefore, the IAEA has developed

and is implementing an approach for

the identification of areas of nonapplicability

of the IAEA safety

standards, to suggest compensatory

measures to close any identified gaps,

in order to address the needs of the

Member States.

The Early Work

The current approach adopted by the

IAEA builds on the early work

performed for the preparation of the

IAEA in TecDoc-1936 [1] establishing

the engineering judgement necessary

to apply the design safety requirements

contained in SSR-2/1 (Rev. 1)

[2] to light water cooled and

high temperature gas cooled SMRs

(LW-SMRs and HTG-SMRs).

A team of international experts

between 2016 and 2018 (see

TecDoc-1936 [1], pg 144-145 ) was

asked by the IAEA to perform a pilot

study to assess, with comments, the

applicability of SSR-2/1 (Rev. 1) [2] to

the aforementioned SMR tech nologies

on the basis of the following criteria:

p Applicable as is

p Applicable with modification

p Applicable with interpretation

p Not applicable

The participants were also encouraged

to include any recommendations

for new criteria not covered in SSR-

2/1 (Rev. 1) [2] and to provide technical

rationale for their recommendations.

Applicable with modification

inferred the need for the text to be

updated for the requirement to be

applicable to the specific design,

whereas applicable with interpretation

inferred the need to modify

definitions of pre-existing terminology

to encompass the new technologies.

The Member States’ contributions

were merged and refined

into one comprehensive working

document to provide an overarching

list of recommendations. The creation

of this working document highlighted

the need for the two SMR designs

assessed to initially be discussed

independently in reference to their

applicability to SSR-2/1 (Rev. 1) [2].

The working document, in its final

form, evaluated the applicability of

each of the 82 design safety requirements

established in SSR-2/1 (Rev. 1)

[2] to LW-SMRs and HTG-SMRs. The

initial findings from the LW-SMR

working group were presented and

published at an international IAEA

conference in 2017 [4]. The working

material developed in this manner

was channelled into an evolving project

report that forms the basis of

Appendixes I and II and Annex I in

IAEA TecDoc-1936 [1]. The IAEA

officers responsible for the development

of this pilot study report were

Kristine M.. Madden and Ramsey

Arnold of the Division of Nuclear

Installation Safety IAEA. The results

of the study were subsequently extensively

used to prepare an IAEA official

publication. The work was completed

by a team of international experts (see

TecDoc-1936 [1], pg 143) with IAEA

responsible officer Palmiro Villalibre

Ares of the Division of Nuclear Installation

Safety in the form of

TecDoc-1936 [1].

Current applicability review


The ongoing review of applicability of

the safety standards builds on previous

experiences and aims to consider

in a holistic manner whether the

current requirements and recommendations

for SMRs cover the safety

issues related to the new possibilities

opened by the novel designs or, on the

contrary, if there are gaps that need to

be addressed to ensure that the level

of safety established by the IAEA

fundamental safety principles will be

complied with.

The level of safety defined by the

Safety Objective and the Safety

Fundamentals [6] is considered as the

departing point for the study. The

review therefore focuses only on

the applicability of the requirements

and recommendations to meet the

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IAEA Approach to Review the Applicability of the Safety Standards to Small Modular Reactors ı Paula Calle Vives, Kristine Madden and Vesselina Ranguelova

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overall high level of safety defined in

the Fundamental Safety Principles:

Safety Fundamentals (SF-1) [6].

It is also expected that key elements

of the safety design approach remain

applicable to these technologies

although additional guidance in the

implementation may be necessary,

such as

p Defence in depth

p The elimination of high radiation

doses to workers

p The practical elimination of early


It is also important to clarify that the

scope of some SSGs may be wider than

the scope of the safety requirements.

These SSGs reflect the best practices in

Member States. The lack of linkage

with safety requirements may lead to

additional consideration on how to

define the design objectives in terms of

acceptability of the consequences of

novel accident scenarios.

To achieve this objective, the

review approach follows four steps

that are presented in detail in this

publication to identify:

p the relevant safety standards to be

considered in the review

p areas of novelty when compared to

operating land-based water-cooled

large reactors

p gaps in the applicability of the

safety standards to SMRs, based on

the areas of novelty identified.

p areas of where the safety standards

may not be applicable or could be

adapted for a better application

to novel design to some SMRs,

based on the areas of novelty


Identification of the relevant

safety areas to be considered

in the review

The safety areas and topics considered

in the applicability review are presented

in the table.

Identification of areas

of novelty

The first step of the applicability

review is the identification of areas of

novelty in the lifecycle of the SMR

when compared with land based

water- cooled large reactors.

The technologies considered as

part of the review include transportable

SMR, micro-sized reactors water

cooled SMRs, and non-water SMRs

(sodium fast reactors, lead fast reactors,

high temperature gas cooled reactors,

molten salt reactors).

The identification of areas of novelty

is based on a systematic comparison

of the characteristics of SMRs with a

Light-water Cooled Reactor Reference

defined as part of the project.

The characterization of these

technologies in terms of areas of

novelty is developed at the onset

based on expert knowledge, literature

review and detailed questionnaires

responses by technology developers,

reflecting designers’ current practices

and claims. This information is then

reviewed by regulatory authorities,

technical support organisations and

Safety Areas


Design and


Fuel Cycle



Facilities and




Operation and



Legal and


Safety Topics

other organisations from member

states participating in the project.

Identification of gaps in the

applicability of the safety

standards to identified areas

of novelty

The areas of novelty identified are

compared to the contents of the

IAEA safety standards in terms of

Site Evaluation for Nuclear Installations

p Site survey and site selection

p Consideration of external events in site evaluation for NPPs

p Dispersion of radioactive material in site evaluation for NPPs

Safety in Design for NPPs

p Safety classification

p The design of key reactor safety systems: the reactor core, the containment and associated systems and

the reactor coolant system and associated systems

p The design of electrical power systems

p Instrumentation and control systems

p The design of fuel handling and storage systems for NPPs

p The application of the human factors engineering in the design

p External hazards in the design

p Internal hazards

p Radiation protection and radioactive waste management

p Construction for nuclear installations

Safety of Nuclear Fuel Cycle Facilities

p Safety of conversion facilities and uranium enrichment facilities

p Safety of uranium fuel fabrication facilities

p Safety of uranium and plutonium mixed oxide fuel fabrication facilities

p Safety of nuclear fuel reprocessing facilities

p Safety of nuclear fuel cycle research and development facilities

p Criticality safety in the handling of fissile material

Predisposal Management of Radioactive Waste and Decommissioning

p Disposal of radioactive waste

p Classification of radioactive waste

p The safety case and safety assessment for the predisposal management of radioactive waste

p Leadership, management and culture for safety in radioactive waste management

p Predisposal management of radioactive waste from NPPs and research reactors

p Storage of radioactive waste

p The safety case and safety assessment for the disposal of radioactive waste.

p Geological disposal of radioactive waste

p Near surface disposal of radioactive waste

p Decommissioning of nuclear power plants, research reactors and other nuclear fuel cycle facilities

p Release of sites from regulatory control on termination of practices

p Storage of spent fuel pool

Safety Assessment for Activities and Facilities

p The structure and content of the safety analysis report

p The development and application to nuclear power plants of deterministic safety analysis and probabilistic

safety analysis

p The conduct of a periodic safety review (PSR) for an existing nuclear power plant

Commissioning and Operations

p Commissioning

p Conduct of operations at nuclear power plants

p Operational limits and conditions and operating procedures for nuclear power plants

p Fire safety in the operation of nuclear power plants

p Maintenance, surveillance and in-service

p Modifications to nuclear power plants

p Core management and fuel handling for nuclear power plants and criticality safety in the handling of

fissile material

p Operating experience feedback for nuclear installations

p Ageing management and development of a programme for long term operation of nuclear power plants

p Chemistry programme for water cooled nuclear power plants

p The evaluation of seismic safety for nuclear installations

p Accident management programme for a NPP

Leadership and Management for Safety (LMfS)

p The operating organization

p The recruitment, qualification and training

p The application of management systems to facilities

p The management system for nuclear installations

p Establishing the safety infrastructure for a nuclear power programme

Legal and Regulation

p Organisation etc. for regulatory body

p Functions and processes of the regulatory body

p Licensing process for nuclear installations regulatory control of radiactive discharges to the environment


Environment and Safety

IAEA Approach to Review the Applicability of the Safety Standards to Small Modular Reactors ı Paula Calle Vives, Kristine Madden and Vesselina Ranguelova

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requirements and recommendations.

Gaps in the safety standards may be

associated to one or several of the following

areas of novelty:

p New barriers, new safety functions

or new provisions to deliver the

safety functions.

p New failure mechanisms, faults,

phenomena that could lead to the

failure of a barrier or a provision to

deliver a safety function.

p Eliminated failure modes, faults,

phenomena by design which

may imply the need for additional

design requirements and/or


p The use of new technologies,

including new fuels, new coolants,

novel safety provisions, novel

materials and construction/manufacturing

techniques that could

lead to the need for additional

requirements and/or recommendations

(e.g. recommendations for

fuel qualification, qualification of

materials to higher temperatures,

use of more corrosive coolants, etc.)

p New operating, maintenance,

testing, refuelling and/or wates

management strategies.

p New facilities and/or activities on

site and/or off site needed to support

the construction, ope ration

and/or post-operation management

of the nuclear power plant.

To ensure exhaustivity, for each of the

above areas, the potential gaps are

closely examined to judge if existing

requirements and recommendations

are sufficiently overarching to address

the specific differences. In some cases,

additional and more detailed review

may be necessary at a later stage to

characterise and confirm the identified

potential gaps.

Identification of areas where

the safety standards may not

be applicable to (some) areas

of novelty

The areas of novelty identified are

then compared to the requirements

and recommendation in the safety

standards. Areas of non-applicability

in the safety standards may be associated

to one or several of the following


p Failure modes, faults, phenomena

typically considered in light-water

cooled reactor reference that are

not relevant to the design, which

may imply some requirements

and/or recommendations may not

be applicable

p Safety functions and provisions to

deliver these functions that are no

longer needed which may imply

some requirements and/or recommendations

may not be applicable

p New operating, maintenance,

testing, refuelling and/or postoperation

management strategies

which may imply some requirements

and/or recommendations

may not be applicable

When areas of non-applicability are

identified, the review also considers:

p If there are associated gaps (not

identified in the gap review)

p If there is sufficient experience to

confirm that the relevant areas

of the safety standards are not

applicable. In some cases, claims

may have not been confirmed by

sufficient operating experience or

there are still considerable uncertainties

related to the areas of

novelty. For these cases additional

features may be needed in the

design until sufficient experience is

available. The potential nonapplicability

and uncertainty will

be captured in the review.

Expected outcomes

The IAEA expects to publish this work

as a Safety Report providing a roadmap

for the applicability of the IAEA

safety standards to novel advanced

reactors and particularly SMRs

throughout their entire lifecycle. The

large team of IAEA experts and international

experts from member states

supporting the development and implementation

of the presented

approach will be acknowledged in the

Safety Report publication.

As a secondary outcome, it may be

possible to further analyse gaps and

areas of non-applicability to identify

potential pathways for resolution and

help to build a further programme

of work to address areas of nonapplicability

and potential gaps.



Design Safety Requirements to Small Modular Reactor

Technologies Intended for Near Term Deployment: Light Water

Reactors and High Temperature Gas Cooled Reactors, IAEA

Technical Document No. 1936, IAEA, Vienna (2021).


Power Plants: Design, IAEA Safety Standards Series No.

SSR-2/1 (Rev. 1), IAEA, Vienna (2016).


Glossary: Terminology Used in Nuclear Safety and Radiation

Protection (2007 Edition), IAEA, Vienna (2007).

[4] K. Madden et al. “Applicability of IAEA Safety Standard SSR-

2/1 to Water Cooled Small Modular Reactors”. Proceedings of

an International Conference organized by the International

Atomic Energy Agency held in Vienna, 6 – 9 June 2017:

Topical Issues in Nuclear Installation Safety: Safety

Demonstration of Advanced Water Cooled Nuclear Power

Plants, V2. IAEA, Vienna (2018).


Modular Reactor Technology Developments, a Supplement to

IAEA Advanced Reactors Information System (ARIS), IAEA

Booklet, 2020 Edition, IAEA, Vienna (2020).


Safety Principles, IAEA, Vienna (2006).


Paula Calle Vives

(Lead Author)

Senior Nuclear

Safety Officer

International Atomic

Energy Agency


Paula Calle Vives is a Senior Nuclear Safety Officer at the

IAEA and the Lead of SMRs and other cross cutting topics

at the Safety Assessment Section. She chairs the IAEA

Working Group on SMR Safety and leads the review of

applicability of the IAEA Safety Standards to novel

advanced reactors. Previously, she was the Delivery Lead

of Advanced Nuclear Technologies at the Office for

Nuclear Regulation (ONR), UK. As a Principal Inspector,

she also undertook roles on regulation of new build and

operating reactors. Before ONR, she was a Senior Safety

Engineer working in UK operating reactors, and

developed proba bilistic safety analysis research in France.

Paula holds a double nuclear engineering master’s degree

(Universidad Politécnica de Madrid and Ecole Centrale de

Nantes) as well as an international relations master’s

degree (University of Cambridge).

Kristine Madden

Associate Nuclear

Safety Officer

International Atomic

Energy Agency


Kristine Madden is a creative and results driven nuclear

industry leader with over ten years of progressive leadership

experience across a broad range of diverse industry

segments, including deterrence, non-proliferation, nuclear

safety, nuclear security and nuclear energy. Kristine is currently

a Nuclear Safeguards Inspector at the Inter national

Atomic Energy Agency (IAEA), where she also previously

worked on SMR and emergency response initiatives

within the Department for Nuclear Safety and Security.

Prior to joining the IAEA, she led licensing initiatives for

the Chernobyl ISF-2 project for Holtec International and

was a Senior Reactor Operator, INPO Engineering Coordinator

and Reactor Engineer at USA based nuclear power

plants. Kristine is completing her master’s degree in International

Relations at the University of Cambridge and

holds a bachelor’s degree in nuclear engineering and

radiological sciences from the University of Michigan.

Vesselina Rangelova

Safety Assessment

Section Head

International Atomic

Energy Agency


Vesselina is the Head of the Safety Assessment Section, Department

of Safety and Security at the International Atomic

Energy Agency, managing the IAEA activities on design

safety and safety assessment of nuclear power plants.

Previously, she led the IAEA Operational Safety Review

Team (OSART) to assess operational safety of Nuclear

Power Plants in IAEA Member States. Before joi ning the

IAEA, she was coordinating the implementation of the

European Commission Joint Research Centre EURATOM

research and training programme on nuclear safety and

security. Vesselina holds a master of science degree in

nuclear engineering from Moscow Power Engineering University

and post graduate diploma in probabilistic safety

assessment techniques from Manchester University.

Environment and Safety

IAEA Approach to Review the Applicability of the Safety Standards to Small Modular Reactors ı Paula Calle Vives, Kristine Madden and Vesselina Ranguelova

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A Zero-power Facility as a Multi-fold

Opportunity to Support Quick Progress

in Innovative Reactor Development

Bruno Merk, Dzianis Litskevich, Anna Detkina, Greg Cartland-Glover, Seddon Atknison and Mark Bankhead

Introduction and history Nuclear has a very unique role to play in a sustainable energy future, since it is the

only currently available technology which can assure 24/7 availability and controllability while delivering massive

amounts of low carbon energy on demand for a net-zero future. However, in the recent decades there has not been any

significant progress in the development of viable innovative nuclear technologies in comparison with the golden age of

the nuclear development (1950’s-1970’s). Most new designs are iterative improvements of the nuclear technologies

developed at that time (e. g. EPR in France, BN in Russia), or are more radical designs with little substantiation with an

exception made for BREST-OD-300 [1], currently under development/construction [2]. Regardless of the different

nuclear technologies studied and developed, the majority of the NPPs built around the world are still light water

reactors. Unfortunately, light water reactor technologies have their limits due to their operational characteristics and

cannot address major challenges which nuclear industry faces at the moment. Core points are: reducing nuclear waste,

the availability of resources to manage assets over 100’s years and the complexity systems leading to elevated cost. To

be accepted by both, business and public, nuclear must deliver and be cost competitive compared to other flexible,

on-demand producing, power plants with similar financial risks applied. Thus, nuclear needs innovations to be more

sustainable, but even more importantly, we need to regrow the trust that nuclear can deliver these innovations. Finally,

we need innovative approaches to reduce the risks associated with nuclear power plant construction becoming complex

mega projects.



Looking back to the most recent

western nuclear reactors put into

operation as well as the current new

build projects, the demand for risk

reduction should be evident. The time

since the last reactor being put into

operation in the west indicates that

we will have a problem when we

intend to rely on experience.

Looking into innovative reactor

development, the last building projects

fall into the 1980ies, followed by

very mixed levels of success on operation.

The German THTR project to

build an industrial demonstrator for

high temperature reactor technology

lasted from 1971 to 1985 with the

permanent shutdown in 1988. The

French SUPERPHENIX construction

took from 1976 to 1985 and the

reactor was permanently shutdown

1998 never delivering an Energy

Availability Factor above 33 % and

most of the time below 15 %. The

UK fast reactor project in Dounreay

indicates comparable dates and outcomes,

construction started in 1966,


Western Reactors

under construction

first criticality in 1974 with a load

factor of below 30 % and the shutdown

in 1994 (all data from [3]).

Obviously, if we want to be successful

in delivering innovative reactors,

we need to learn again, and this

should happen in a smart way. The

key will be to receive timely feedback/

quick response on the decisions made

instead of the long lead times which

results typically in high costs when

late adaptions are required, see e. g.

the Olkiluoto or the Vogtle project,

where changes in the later construction

phase have not only led to higher

costs but also to massive time delays

which is maybe even more important.

To support the required learning,

we need an innovative and efficient

approach, start smart and small –

looking back to early reactor developments,

zero/low power reactors have

been used as a test bed for the next

steps [5, 6] which seems to be highly

promising. The main challenge will be

to make the best out of the money and

to use the time wisely.




start year

USA Watts Bar-1 WH 4LP 1973 1996

USA River Bend GE BWR 1977 1985

France Chooz B N4 1984 1996

France Civaux N4 1988 1997

USA Watts Bar-2 WH 4LP 1973/2007 2016

| Table 1

The last constructed nuclear power plants and their grid connection [3].



p How is starting small possible

in a highly complex multi-billion


p How did we do this in the 50ies and

60ies? Can we repeat this? What

do we need to do differently in the

21 st century?

p How important are collaborative

opportunities to support upskilling

and engineering development?

The fundamental problem is, when

building an innovative reactor there is

no experience, no plan, so appropriate

cost management is almost impossible

because we don’t know all the steps,

the required technologies, and the

challenges (unknown unknowns).

Introducing a structured process to

the R&D will be a key requirement and

will help to define a structured

approach to the first of a kind (FOAK)

or the later serial build. Learning on a

small real project and going in steps

will allow us to achieve a more

efficient cost reduction than just

learning from experience which typically

takes place at a very later stage of

the project which leads to delays and

cost over runs. These multiple arguments

speak for starting a new, innovative

reactor programme on a small

scale using a zero-power reactor to

reduce the risk of the whole development


Why do we need this program?

The last indigenous reactor in the UK

was constructed 1980 and put into

operation in 1988, while the design

Research and Innovation

A Zero-power Facility as a Multi-fold Opportunity to Support Quick Progress in Innovative Reactor Development ı Bruno Merk, Dzianis Litskevich, Anna Detkina, Greg Cartland-Glover, Seddon Atknison and Mark Bankhead

atw Vol. 66 (2021) | Issue 3 ı May


The Dungeness disaster

Construction on the new AGR at Dungeness B started in

January 1966. A later historian of the privatization of the

British electricity industry described it as “the single most

disastrous engineering project undertaken in Britain”

[Henney (1994) p. 131]. Among a certain generation of

people, Dungeness B is still a byword for failure of

construction, design and project management on a heroic

scale. The project was beset by delays, strikes and cost


Henney, A (1994). A Study of the Privatisation of the Electricity

Supply Industry in England & Wales,

London: Energy Economic Engineering

| Figure 1

Simon Taylor (2016) The Fall and Rise of Nuclear Power in Britain:

A history [8].

also occurred several decades earlier

and the knowledge was not passed

onto the next generation. This has led

to a significant reduction in the

number of the specialists in the

nuclear sector. Looking deeper, the

last indigenous development of a

reactor has been delivered in the late

1960ies, see Figure 1. This development

was pushed by an ambitious

construction programme aiming to

deliver five twin reactor stations and

was quickly rolled out to support

business since export orders were

eagerly anticipated. Thus, the situation

seems to be a bit like the todays

nuclear renaissance supported by

the BEIS (Department for Business,

Energy & Industrial Strategy) nuclear

innovation program (NIP) [7] with

the aim to produce business opportunities

for UK plc and to become a top

table nation in nuclear latest in 2050

to support the green recovery.

The lead station of the AGR program

was Dungeness B which could

be seen as industrial demonstrator

and a first of a kind and it was a direct

step into a large station without real

stepwise development. It was ordered

in 1965 with a targeted completion

date of 1970. The project did not

progress as expected, being several

times delayed after problems in many

aspects of the reactor design, a bit

comparable to today’s mega projects,

see Figure 1. Finally, electricity generation

began in 1983, 13 years late,

while full power was reached for the

first time in 2004, roughly 38 years

after construction began [8]. Another,

early example how costly and time

consuming it can be to learn on a full

power project. The last, more successful,

reactor of the AGR fleet was connected

to the grid in 1989, thus the

last classical UK thermal reactor project

finished construction more than

30 years ago. The last delivery in the

innovative reactor program was the

prototype fast reactor (PFR) which

was announced in 1966 to be built at

Dounreay. The PFR achieved first

criticality in 1974 and grid connection


Thus, the design of the reactor

system of the commercial fleet took

place in the early 1960ies and the

design of the innovative reactor

system just shortly after, leading to

the situation that the last experience

of construction, commissioning, and

connection to the grid took place in

the late 1980ies [3]. This is a UK view,

but only the dates will be slightly

different in other western countries,

while the introduction just shows that

the situation is comparable. Maybe

the length of time period will be

slightly smaller, but in all cases, it is

too far back in time to rely on the

experience gained at that time.

The key questions to answer are:

p What should we learn from this

history to avoid repetition of such a

very costly disasters – costly in

regards not only to money, but also

with regards to time?

p How can we re-gain experience

and quick response in the whole


p How can we reduce the risk in the

project as mentioned at the end of

the introduction?

A key point will be to learn and to

re- educate experts for the nuclear

renaissance since the historic expertise

is obviously lost. In addition, we

can neither afford massive delays

which are predictable and costly when

problems appear at the very late stage

of a project, e.g. in the middle of

construction, nor do we have time to

waste if nuclear should make a

real contribution to a future net-zero

society. Luckily, the situation still

allows us to deliver on these tasks if

we start now and if we use time and

resources wisely. Moreover, in comparison

with the 1960ies we have

more robust and efficient simulation

tools which should speed up the R&D

activities. Digitalisation will help the

whole process via end to end support

and by adopted working practices

instead of simply sending more information

to key stakeholders creating a

decision-making bottleneck. To make

this possible some tools require

targeted validation for the innovative

reactor designs to leverage their

full potential and to reduce time of

development and costs significantly.

The learning has to be supported

by creating a structured programme

from feasibility through to construction,

see Figure 2, in combination

with following the recently proposed

4 step process [6] consisting of preliminary

studies, an experimental

phase starting with the zero power

reactor as the key steps towards

feasibility. This will support the smallscale

demonstrator providing information

for the preliminary design

with the first experience of nuclear

power production in a new kind of

reactor. However, in an innovative

reactor development, FOAK is going

all the way through this cycle in each

step. We need to build a complete

programme at sufficient detail encompassing

all of the R&D and skills

development required to effectively

project manage the delivery of each

step right-to-left (thus backwards)

engaging all of the stakeholders at

each level in the process.

| Figure 2

A structured program for the development of a nuclear reactor along the recommendations in a WNA white paper [9].

Research and Innovation

A Zero-power Facility as a Multi-fold Opportunity to Support Quick Progress in Innovative Reactor Development ı Bruno Merk, Dzianis Litskevich, Anna Detkina, Greg Cartland-Glover, Seddon Atknison and Mark Bankhead

atw Vol. 66 (2021) | Issue 3 ı May

All mentioned points demonstrate

that we need a new strategy to speed

up learning by identifying strengths

and weaknesses of the capabilities

and the current capacities available to

be able to deliver the end-to-end

approach developed above. Key will

be to work on the known unknowns

and to identify early the unknown

unknowns – areas where the community

is weak, but where we are not

aware of the weakness or the lack of

knowledge. Testing procedures and

technologies early and on smaller

scale will be of high importance to

avoid costly late failures.

Opportunities of a zero- power

reactor as a first step

Developing and delivering an indigenous

zero-power facility should be the

most promising first step into any

innovative reactor program as a part

of an active risk limitation program

for the whole nuclear reactor development.

The zero-power facility has the

potential to be used as a multi-fold

opportunity, since it is more than a

system that can be used for the validation

of numerical models and their

inherent approximations. It is a FOAK

and the opportunity to go through the

whole process from design to operation

of an innovative reactor facility

testing the feasibility, but in contrast

to any larger reactor it is delivering a:

p low cost opportunity compared to

a power reactor due to limited size

and significantly reduced system


p low risk opportunity in time,

finance, and nuclear – it is not

rocket science, GUINEVERE [15]

has finally been successfully

delivered – here the reduced complexity

is key, it reduces the number

of critical tasks and the required

safety systems. However, all key

components for the nuclear island

and the fuel production have to be

designed, regulated, and delivered

p less complex project, no heat transfer

and no power conversion

system are needed, no extensive

multi-redundant and diverse safety

systems are required as well as no

expensive mitigation devices like a


p quick response opportunity, since

such a project should not take

more than 3 to 5 years, a quick

turnaround and an accelerated

learning curve will be seen.

Knowledge and capacity gaps will

be identified in short time creating

less costly opportunities to close

gaps and even change/adapt the

final pro duct in a comparably late

project phase.

p High flexibility of the facility itself

which could be equipped with

a new core (as done in the

GUINEVERE project) if another

technology should be investigated

A zero-power facility for a new technology

is a comparably small project,

which still requires the whole production

chain for a nuclear reactor, while

it requests collaboration in an interdisciplinary

team. Thus, it will be a

perfect test case for the readiness for

future, larger projects, assuring an

accelerated learning curve in an innovative

reactor technology on:

p designing,

p licensing,

p constructing,

p commissioning, and

p operation

Where can these advantages

be delivered?

As previously mentioned, the zeropower

facility is a low cost, low risk,

quick response project which delivers

opportunities on different levels, see

Figure 3.

The opportunities of the facility are

in detail:

p Manufacturing

Manufacturing an innovative

reactor of a new technology will

help identifying weak points

( unknown unknowns), upskilling

demands, and already available

pockets of expertise. It will allow

developing and testing of new technological

approaches and advanced

manufacturing techno logies on a

small scale and support the creation

of a core team of experts with

real hands on experience for the

following small scale demonstrator

which would make the UK an

| Figure 3

The multiple opportunities which can be delivered in a zero-power facility.

attractive location to deploy these

designs. Testing of new components,

e. g. establishing a pre-industrial

fuel production. It will help

creating and educating the required

supply chain for the technologies.

All points will be essential for progressing

into the next step of the

development process – the smallscale


p Experiment

On the one hand, the experiment

will help in the education and

the qualification of future reactor

physics experts, which are highly

demanded worldwide. On the other

hand, it will help to improve the

recognition of reactor physics and

new reactor technologies. Thus, it

will attract bright students of future

generations into nuclear. The

investment in an experiment will

showcase the innovation potential

in nuclear technologies and the

drive to innovate to the public.

p Leading Science

Taking the lead through an investment

into advanced reactor technologies

such as the proposed

molten salt reactor technology.

The investment into the zeropower

facility will create a sustainable

long term claim in an innovative

reactor technology. The facility

will create the opportunity to provide

safety demonstrations and

code validation and deliver an

accelerated learning curve for the

operating entity as well as the local

academic community. The demonstration

opportunity will help

creating new IP for the country.

The facility will attract top scientists

to the country either in collaborations

or through relocation

while giving UK plc an advantageous



Research and Innovation

A Zero-power Facility as a Multi-fold Opportunity to Support Quick Progress in Innovative Reactor Development ı Bruno Merk, Dzianis Litskevich, Anna Detkina, Greg Cartland-Glover, Seddon Atknison and Mark Bankhead

atw Vol. 66 (2021) | Issue 3 ı May


An already successful example:

p Business Opportunity

Finally, besides the leading science,

the facility will allow experiments

for international partners and for

industrial developers who cannot

afford to build their own zeropower

system, as has been

delivered for decades through

the BFS at IPPE Obninsk for international

sodium fast reactor

development or through the new

opportunities of GUINEVERE at

SCK∙CEN at Mol for lead cooled

fast reactor technologies. The

facility will serve industry to

support the home-grown supply

chain and link them to reactor

developers while earning money

through paid experiments.

How can these advantages be


The key for the success will be to make

the most out of the money invested, as

well as to use the time available

wisely. The zero-power reactor project

has to deliver much more than only

results for code validation or safety

demonstration, which would be the

outcome of doing paid experiments at

another facility. Possible opportunities

are given above.

A zero-power reactor project can

build on these first approaches

delivered in project FAITH (see text

box), but it can and has to go much

further. The accelerated learning curve

starts already with the design and

manufacturing of a facility to study

innovative reactor development and

operation, not with the experiment.

Creating, enabling, and edu cating the

supply chain on a very small scale and

reduced complexity system, as a basis

for the next level of the small-scale

A first demonstrator of this approach is Project FAITH (Fuel

Assembly Incorporating Thermal Hydraulics) a multi- purpose

project using new, highly innovative approaches to make

better use out of the invested money. Main side purposes are:

Educating new partners from outside of the nuclear industry

how to deliver on nuclear standards while using already

established innovations from other technologies, e. g. modular

manufacturing established in ship building or application of

tailored materials through additive manufacturing. “In FAITH

we intend to demonstrate modular manufacturing on small

scale with low cost and complexity to quickly evaluate a key

technology for small modular reactors, while creating an

opportunity for qualification and education of the strongly

demanded workforce. This is delivered by a stepwise approach

from easy to build and operate experiments into future

cutting- edge science and technology with a complex and

challenging fluid. All surrounded by digital design and

development technologies from cradle to grave as well as the

approach to deliver a project management integrated with the

technical delivery. This will allow to include product quality

management into the digital twin as well as thinking in terms

of the whole project lifecycle using a common modelling

environment.” [9]

power demonstrator. Key points will be

to develop and test new approaches

(modular manufacturing, advanced

fuel production, and applying digital

twin technology across the whole lifecycle

of the asset), accept failure and

be prepared for a quick for recovery to

support rapid developments, but in

all cases by using small steps. This

approach reduces risk and promotes

learning and solving problems at each

step. Learning has to be seen as a process

making progress based on UK

capabilities and capacities instead of

just buying a product. It is about

involving all main suppliers into the

development instead of having just

suppliers delivering their parts. This

also implies using the available nuclear

chemistry expertise of academic partners

to improve the available database

for the pre- experiments required for

the design, as well as upgrading of

existing facilities to be able to deliver

on the new challenges, e.g. salt based

uranium fuels production. A further

opportunity is refurbishing existing

facilities and retaining the highly

skilled employees at these facilities

thus serving as a social-economic development

to support a new facility as

in the case of the VENUS facility at

SCK. This will be complemented by

linking with leading groups from outside

nuclear energy to involve them in

the project and attract available expertise

from other areas, e. g. detector

development for particle physics delive

ring UK’s contribution to CERN experiments

or modular manufacturing.

It is about using the experiment

to deliver a hands on education to give

the future experts a tier-one experience

in building a new type of reactor as well

as to operate the facility instead of

completely relying on modelling & simulation

as it has often become tradition

in reactor physics. The facility will offer

very effective accelerated learning to

the next generation of engineers and

scientists that comes with de signing,

developing and constructing the facility

as well as running and ana lyzing the

experiments. The facility will be at the

centre of a user community and

attracting international experts while

growing an experimental program for

a new type of zero- power experiment

in collaboration with national and

international partners. In addition, the

facility will allow the testing of new

detector technologies in a challenging

environment and potentially invest

into developing some tailored, innovative

detector technology.

The development of zero-power

experiments will proceed from easy

to complex to support the learning

process, a further example of learning

from project FAITH. Most probably, the

experimental campaign will be started

with experiments based on a solid salt

block operating at room temperature

to learn how to apply experimental

procedures from the ground, to test

detector technologies and establish the

data acquisition systems, while providing

first code validation data, but

keeping the commissioning process at

a much lower risk than a full power

system. This will be followed by the

much more complex experiments

using a liquid molten salt core to

demonstrate the real operational

behaviour of a liquid core including

feedbacks, power distribution, and the

effects of density changes which are

typically hard to observe and demonstrate

to the required accuracy with

traditional modelling and simulation.

Besides the technical advantages,

the investment into the development

and delivery of a zero-power facility

will demonstrate leadership in science

in an innovative reactor technology.

This is essential since “the start of a

nuclear programme is often associated

for with the first significant

reactor experiment” [6], thus the

project will create a major claim in

innovative nuclear of the 21st century.

It will mark a clear step for preparing

to become a leading player in new

nuclear in 2050 as it is expected in the

BEIS nuclear innovation program [7].

The zero-power experiment marks

a key crossroads for a technology, since

this facility will allow the delivery of

experiments which are essential for the

progress of a new technology to accelerate

the development process. On the

one hand, it is the first time that codes

can be evaluated on the real reactor behaviour

of a critical system. On the

other hand, it is the first time that

safety demonstrations can be delivered

which involve the neutronic behaviour

of the system. If the zero-power facility

is designed in a smart way, it will even

allow to deliver first coupled safety

demonstrations of a liquid core considering

not only the neutronics but

also thermodynamic effects and thermal

feedback effects. Typical, essential

safety de monstrations for a new, innovative

technology, thus a broad range

of proposed innovative reactor designs,

are required to be delivered through

experimental confirmation for licensing

of a power operation system are:

p of core criticality;

p of neutron flux, energy, and power


p of reactivity coefficients;

Research and Innovation

A Zero-power Facility as a Multi-fold Opportunity to Support Quick Progress in Innovative Reactor Development ı Bruno Merk, Dzianis Litskevich, Anna Detkina, Greg Cartland-Glover, Seddon Atknison and Mark Bankhead

atw Vol. 66 (2021) | Issue 3 ı May

| Figure 4

Opportunities in the different steps given by a zero-power facility at one glance.

p of changes in reactivity and flux as

a function of salt density, temperature

and composition change

Applying a smart design of a zeropower

facility for molten salt technology

will allow these demonstrations

without the requirement for a

considerable nuclear power production,

which typically requires a

powerful cooling system and strong

radiation protection measures.

Delivering the zero-power facility

will create a focal point for a longerterm

game changer technology which

will support the formation of the

teams and educating the specialist for

the next step in the process. The

facility opens the opportunity for

spin-offs of the technology already at

a very early stage through paid

experiments before achieving the

industrial scale demonstrator, see

Figure 4. The zero power experiments

help accelerating the next steps and

avoid potential mistakes (which can

be really costly for a large-scale

demonstrators) due to the availability

of experience and expertise with a

real project. The opportunity of quick

studies in a safe setting to test technologies

and to optimize new

approaches will create very valuable

experience and data. A role which has

been described through the development

of the German HTR program

where the zero-power experiment

KATHER was set up very late for the

design phase of the industrial demonstrator


However, it is important to keep in

mind that the use of the facility will

not be finished when the demonstration

and validation experiments

are finished. As described in the THTR

program the facility will help to speed

up the design process and reduce risks

during the small scale and later the

industrial demonstrator projects for

the iMAGINE technology [6]. The

facility has a strong potential to

support the education of future

reactor physics specialists through the

access to real world experiments. In

addition, zero-power reactors are a

well-recognized tool to deliver experiments

for money for start-ups around

the globe (e. g. Seaborg, TerraPower,

Moltex, Terrestrial Energy, etc.) to

support their development and their

interaction with the regulator as it is

today delivered at the BfS facility

in Obninsk [12, 13] and in the

GUNIEVERE facility in Mol [14, 15].

Figure 4 gives a collection of the

opportunities delivered through the

life of a future zero power facility.

How would the next steps

look like?

As already discussed the zero power

experiment is the first real world step

in the process of the development of

an innovative reactor program [6]

which delivers technology specific

hardware – thus it is often seen as the

start in a new reactor program leading

to the small scale and the industrial

demonstrator, see Figure 5. The role

of the facility for risk reduction has

been recently described by a highlevel

expert, the general director of

JSC “NIKIET”, in the opening remarks

for the Russian MSR project in

Zheleznogorsk [6] in October 2019.

“We all have to solve an extremely

ambitious task – to create a research

reactor here. There is no similar real

facility anywhere in the world. I am

| Figure 5

The process to develop an innovative, new reactor system, required governmental

investment structure in a successful program and resulting skills development and growth.

convinced that we will succeed, we

will be the first. … we will go in stages.

First of all, the creation of a research

reactor for testing technologies. Let‘s

move on to a large reactor with more

powerful parameters, having completely

developed the underlying technology.

The path is not fast, but it is

new, and it is impossible to not take

risks. At the same time, it is logical to

build our work as parallel as possible

in order to save time.” Thus, reducing

the risk is the key point even for the

very experienced Russian specialists.

For a country which has not delivered

an indigenous reactor for decades, the

other key point is creating a project

tolerant for expected failure through

developing methods to quickly recover

with reasonably small risk in time and

cost. This will assure an effective,

accelerated learning opportunity

which has to be delivered alongside a

consequent stepwise learning process

from one step to the other. Thus, the

approach is to lead by applying as

much testing and learning as possible

in the smallest and least complex units

as possible while using the experience

of the last step to support the next

one. This will assure the parallel development

of capabilities and capacities

where the core group of one step

will form the seed for the much larger

team required for the next step.

| Figure 6

Possible spin-offs in the different development steps during the process to develop an innovative reactor system.


Research and Innovation

A Zero-power Facility as a Multi-fold Opportunity to Support Quick Progress in Innovative Reactor Development ı Bruno Merk, Dzianis Litskevich, Anna Detkina, Greg Cartland-Glover, Seddon Atknison and Mark Bankhead

atw Vol. 66 (2021) | Issue 3 ı May


Considering all focus on the zero

power reactor experiments, it must be

clear it is only the first of the steps

required on the way to delivering

an innovative nuclear system, see

Figure 5 and Figure 6. For any kind of

investment planning, the multi-fold

opportunities of the zero-power

facility are a perfect example of

creating early wins on the way

through the process by delivering

more than just a facility to do the

required experiments. These spin-offs

are essential, due to the long timescales

of nuclear programs, since they

allow the investors to create some

early revenues, even before the final

step is delivered. These revenues can

be financial like paid experiments, but

in nuclear with the strong demand

on highly qualified subject matter

experts and complex manufacturing

challenges the most valuable spin-offs

are provided by growing capabilities

and capacities. However, for investors

into a successful new build program

based on innovative reactors it seems

that the risk reduction in cost and

delivery schedules through the stepwise

approach forms a key part for a

successful program.


The last innovative reactor projects

have been delivered more than

40 years ago, thus it will be almost

impossible to rely on the experience

from these projects. In addition,

recent reactor projects have suffered

from massive cost overruns and time

delays due to changes in a very late

project stage. Learning from this, for

innovative projects we need much

quicker feedback since the number of

unknowns and thus the risk will be

much larger than in LWR technology.

Thus, a new, historically proven way

to develop this industry is required. At

the point entering into a new, innovative

nuclear reactor technology, it is

important to find a new way to reduce

the project risks of each of the process

steps as a first of a kind.

The first step is traditionally via

zero power experiments. However, we

have highlighted here that the experiments

are only a small part of the

opportunities given by a zero-power

facility. Developing a zero-power

facility will deliver on several levels

starting with manufacturing of the

facility and the components which

demand the development of capabilities

and capacities while delivering a

strong learning process which is

required after no innovative reactor

has been built in the west and no native

reactor has been designed and built

within the last few generations within

the UK. The next required opportunity

will be provided by the experiment itself

which will help to grow capabilities

and capacities in operating a reactor

and developing experiments which in

turn will provide the chance for quick

learning. Investing into a zero- power

facility will demonstrate the willingness

to lead and the operation will deliver

leading science, providing unique

results and the oppor tunity to deliver

the very valu able scientific data for

code validation, but also the chance to

provide the essential experiments

which will be demanded for the regulation

process of a future small-scale

demonstrator. Finally, after the most

promising cutting-edge science feat of

delivering the experiments for the

countries own program, the zeropower

facility will give a good business

opportunity to deliver experiments on

demand for national and international

scientific and industrial partners.

On the one hand a zero-power

facility requires the same steps as that

of any full-scale reactor development

which is required; designing, licensing,

constructing, commissioning, and

operating of a nuclear facility. On the

other hand, such a facility is a low-cost

opportunity with limited size and

significantly reduced system complexity,

being a low risk opportunity in time,

finance, and nuclear – here the reduced

complexity is very helpful since it

reduces the number of critical tasks,

while all key technologies for the

nuclear island are required, but the

consequences of potential accidents

and the related mitigation measures

are not needed. However, due to the

reduced complexity, neither requiring

heat transfer and no power conversion

nor extensive multi redundant and

diverse safety systems, the adventure is

easier to overview and it will lead a

quick response. Delivering such a

facility should not take more than 3 to

5 years assuring a quick turnaround

and a accelerated learning curve.

All points together demonstrate

that a zero-power facility is a great,

multi- fold opportunity which could

deliver a quick and very efficient start

into a new, innovative nuclear program.


[1] Dragunov, Yu & Lemekhov, V. & Smirnov, V. & Chernetsov, N.

(2012). Technical solutions and development stages for the

BREST-OD-300 reactor unit. Atomic Energy. 113. 10.1007/


[2] Construction licence issued for Russia‘s BREST reactor,

available: https://www.world-nuclear-news.org/Articles/

Construction-licence-issued-for-Russias-BREST-reac, accessed


[3] https://pris.iaea.org/PRIS, accessed 22/03/2021

[4] Barakah Nuclear Energy Plant, available: https://www.enec.

gov.ae/barakah-plant/ , accessed 22/03/2021

[5] Government and Industry Roles in the Research,

Development, Demonstration, and Deployment of Commercial

Nuclear Reactors: Historical Review and Analysis. EPRI

2017. 3002010478

[6] B. Merk et al: “iMAGINE - A disruptive change to nuclear or

how can we make more out of the existing spent nuclear fuel

and what has to be done to make it possible in the UK?”,

atw 6/7 2019

[7] B. Merk et al. The UK nuclear R&D programme on digital

nuclear reactor design - modelling, simulation, and virtual

engineering, ICAPP 2018 : Charlotte, NC, 8-11 April 2018

[8] Simon Taylor (2016) The Fall and Rise of Nuclear Power in

Britain: A history, UIT Cambridge (2 Mar. 2016),

UIT Cambridge Ltd., Cambridge, United Kingdom

[9] Lesson-learning in Nuclear Construction Projects, World

Nuclear Association, April 2018, Report No. 2018/002

[10] M. Bankhead, B. Merk: Project FAITH description, c

urrently submitted to IMGENIA

[11] V. Drüke & D. Filges (1987) The Critical HTGR Test Facility

KAHTER–An Experimental Program for Verification of Theoretical

Models, Codes, and Nuclear Data Bases, Nuclear Science

and Engineering, 97:1, 30-36, DOI: 10.13182/NSE87-A23493

[12] Profile SFR-64, BFS-2, RUSSIA, available: https://nucleus.iaea.


SFR-64%20Russia%20-BFS-2.pdf, accessed 22/03/2021

[13] I.P. Matveenko et al. EXPERIMENTAL STUDIES of BREST-


available: https://inis.iaea.org/collection/NCLCollectionStore/

_Public/32/021/32021979.pdf, accessed 22/03/2021

[14] GUINEVERE: Generator of Uninterrupted Intense Neutron at

the lead VEnus REactor, available: https://science.sckcen.be/

en/Projects/Project/GUINEVERE, accessed 25/11/2020

[15] H. Aït Abderrahim and P. Baeten, “The GUINEVERE-project at

VENUS, project status,” in ECATS Meeting, Cadarache, France,

January 2008.

[16] https://www.sibghk.ru/news/9068-na-gkhk-proshlorabochee-soveshchanie-po-voprosu-sozdaniyazhidkosolevogo-reaktora.html


Prof. Bruno Merk

(Lead Author)

School of Engineering,

University of Liverpool,

United Kingdom


Prof Bruno Merk is currently holding a Royal Academy

of Engineering Chair in Emerging Technologies for

advanced nuclear technologies. From 2015 to 2020,

he was holding the NNL/RAEng Research Chair in

Computational Modelling for Nuclear Engineering and

was NNL Laboratory Fellow for Physics of Nuclear

Reactors. Prior to moving to the UK, he was in a

leading position in the Helmholtz nuclear research

program NUSAFE and was advising the German

Academy for Science and Technology in the topic

nuclear waste management, giving political


Dzianis Litskevich

Anna Detkina

Seddon Atknison

School of Engineering, University of Liverpool,

United Kingdom

Greg Cartland-Glover

Scientific Computing Department, Science and

Technology Facilities Council, Daresbury Laboratory,

SciTech Daresbury, United Kingdom

Mark Bankhead

National Nuclear Laboratory, United Kingdom

Research and Innovation

A Zero-power Facility as a Multi-fold Opportunity to Support Quick Progress in Innovative Reactor Development ı Bruno Merk, Dzianis Litskevich, Anna Detkina, Greg Cartland-Glover, Seddon Atknison and Mark Bankhead

atw Vol. 66 (2021) | Issue 3 ı May

The Thorium Network –

An Introduction to Blockchain for SMRs

Dian Kemp, Hulmo Christiaansen, Yvette Kemp and Jeremiah E. Josey

Worldwide interest in adopting SMRs is on the rise. “SMRs everywhere” necessarily are safe, reliable and secure,

and this requires tracking tools for all activities of energy production. These tools answer questions of: “Where are the

SMRs?”, “What stage of their life cycle are they?”, “Where is the fuel in transit?”, “Where is the spent nuclear fuel?”,

“Where are the intermediate and low-level waste materials?”.

All of these questions can be answered

with one word: Blockchain.

Uncrackable, unhackable, immutable,

distributed: blockchain is the

modern marvel of the 21 st century.

The best example is the safe, secure

management of over 1 Trillion USD in

assets by the Bitcoin Protocol – the

leader in the Blockchain establishment

and growing from zero in 2009

to where it is today in only about 10

short years. It is used by millions of

people to store and transfer value all

over the planet.

But what does this have to do with

Small Modular Reactors (SMRs)? or

“Burners” as we like to call them.

Well, a lot actually. The present world’s

energy production from nuclear

energy is a little more than 10 %. And

that comes from about 440 installations

worldwide. With small burners

everywhere in the range from micro

(5 MW) to small (200 MW) and predicting

an uplift to 30 % of nuclear

energy production (as project financiers

and environmentalists converge

on the idea that wind and solar just

can’t do it). The number of machines

worldwide would balloon from current

numbers to perhaps 20,000 installations

or more. It’s a scenario screaming

for digitization. Blockchain does it

very very nicely.

But don’t worry about being first.

There are thousands of blockchain

projects worldwide today. Food

producers, shipping, even governments

are looking to move their entire

operation onto blockchain (Estonia

and Dubai are two leading examples).

Here’s a list of industries and how

blockchain is being deployed:

p Secure sharing of medical data;

p Music royalties tracking;

p Cross-border payments;

p Real-time IoT operating systems;

p Personal identity security;

p Anti-money laundering tracking


p Supply chain and logistics monitoring;

p Voting mechanisms;

p Advertising insights;

p Original content creation;

p Cryptocurrency exchange;

p Real estate processing platform;

IBM alone has been involved in over

400 blockchain projects ranging

from supply train logistics, shipping,

food and payments. So it’s only a

matter of time until Blockchain goes


In the typical nuclear energy

production process, materials require

safeguarding due to the danger

these materials pose for weapons

manu facture and uncontrolled radiation

exposure. Safeguarding requires

a significant amount of administrative

paperwork. Digitization of this adminis

tration reduces the environmental

and financial costs of safeguarding

material from nuclear energy production.

However, housing all that

information in a single digital

location makes it vulnerable to a

single point of failure, malicious

attack, mani pulation and falsification.

With the anticipated expansion of

SMRs worldwide, this system is

destined to fail. By using a blockchain,

this problem is circumvented

through the design and use of the


The Thorium Network’s Honey

Badger TM is the first commercially

available decentralized nuclear lifecycle

tool that derives its security from

Blockchain. It is designed to be used

to digitize the supply chain of nuclear

materials, such as radioactive isotopes

or nuclides, and the machines producing

energy from them – the

“Burners”. The blockchain shares the

information over multiple nodes, peerto-peer,

it is censorship-resistant, with

each node using encrypted channels,

and every authorized party having a

copy of the blockchain. This safeguards

the information by prohibiting

a single point failure removing the

chance of a malicious party changing

critical information such as enrichment,

plutonium and fission product


| Thorium in a bottle.

| Estimated Return in Investment in Energy Sytems

(Source: http://www.ansto.gov.au).

The blockchain is monitored on a

trust-less basis whereby everybody on

the network verifies it for itself and

checks each change. The resulting

consensus derives from the rules

requiring you to be compliant in such

a system. This makes it impossible

to maliciously change information

on the blockchain without anyone

noticing, as any changes will immediately

be recognized and be evaluated

for truth by the network. For this

reason, the integrity of the information

can be maintained indefinitely

while digitizing the information

and making it easily available to all

involved/authorized participants. In

order to improve access to the right

documents, a database of hash and

documents will be included within the


Research and Innovation

The Thorium Network – An Introduction to Blockchain for SMRs ı Dian Kemp, Hulmo Christiaansen, Yvette Kemp and Jeremiah E. Josey

atw Vol. 66 (2021) | Issue 3 ı May


| Thorium molten salt equipment: Circulation-loop.

blockchain. This will allow the documents

to be easily referenced while

keeping the document details and

hash connection secure.

A brief intro for the thorium

network and our ethos

The Thorium Network TM (TTN) is a

Swiss-based nuclear firm with the

objective of delivering thorium to the

market using blockchain technology.

The security and transparency of the

blockchain will allow for a digital

revolution in the manner in which we

will monitor and protect nuclear

energy. Small Modular Reactor (SMR)

technology is anticipated to expand

rapidly in the next decade. Non-

Nuclear-Proliferation Treaty (NPT)

countries will pursue this technology

and if ineffective monitoring of the

material is allowed to pass, then we

can see 3 rd parties use the material.

For malicious means.

Placing all orders for fuel and

SMRs onto the blockchain. By

making it secure and transparent, will

allow non-NPT countries to pursue

nuclear energy. The blockchain will

allow for effective oversight and

monitoring of all SMRs from all over

the world from the comfort of your


The expansion of SMR technology

worldwide will require effective

oversight which is unhackable, unchangeable

and available for a very

long time. The same blockchain will

be effective in the implementation of

Smart contracts, fuel transfer, waste

management and recording of the

material over a long period of time.

The blockchain is currently being

implemented in the transport and

transparency of medical isotope

transport, including value recording,

shielding calculations, on-time delivery

and faster more reliable delivery

of the medical isotopes.

The blockchain

The development of a thorium supply

chain has given The Thorium Network

new opportunities. These include the

upgrade of current nuclear supply

chains, such as nuclear equipment,

nuclear fuel, nuclear waste, and

medical isotopes using The Thorium

Network’s blockchain called Honey

Badger TM .

The problem with medical isotopes

is that from the point of production

the material has a short half-life. In

order to transport this material from

the production facility, a coordinated

group effort must be implemented

with all paperwork in place and all

transport approved. All of this documentation

traditionally is placed in a

hard copy which increases labor and

slows down an already time-sensitive

process. The advantage of using

blockchain technology is that all of

this paperwork can be compiled digitally

and be sent along with the supply

chain/blockchain. This will speed up

the process, reducing lost product

due to time delays in delivery and

incorrect paperwork. By using a

digital system using similar supply

chains and blockchains has reduced

cost by up to 70 %.

Going digital also allows for the

development of Smart contracts and

the ability to conduct online radiation

shielding calculations. It also allowsfor

real-time monitoring of the

package, its location and the status

of the container which houses the

isotopes. All of this information,

placed on the blockchain, will be

transparent to all approved interested

parties. This way the airline can see in

real-time the location of the transport

truck, the condition of the container,

time to delivery, the criticality of

the material, and have all necessary

paperwork for the journey already

on hand. This allows for better

| Thorium molten salt equipment: Purification.

coordination in the aircraft regarding

the location of the container, and if

any delays occur the airline is notified

timeously. By connecting a number of

transport logistics firms, in the event

that due to circumstances beyond the

firm’s control, like weather hold or

a change of aircraft, alternative

arrange ments can be made timeously

such that a minimal disruption of

product quantity occurs.

By going with a blockchain and the

supply of thorium, we are introducing

a new cryptocurrency token which will

be equivalent to 0.232 g of thorium

atoms. This token will be tradable on

the Swiss crypto exchange, similar to

other crypto- currency and will be used

as payment on the blockchain for

medical isotopes, fuel, components

and utilization of the blockchain.

The development into these new

fields increases the number of specialists

required such that expertise is

available for every facet of the nuclear

supply chain. This led to the creation

of a nuclear consultancy group called

SAFE Fission Consult TM . This group

is an international multidisciplinary

group in all fields related to the

nuclear fuel cycle, from universities to

accident investigations, financing of

nuclear plants, legislation creation,

new international nuclear programs,

mining and production of raw

materials by chemical means.

The senior advisory group is small

and can thus work fast while our list of

consultants is growing day by day.

This team is unique in the world due

to the length and breadth of experience

it has and the fact that today,

with zoom and the internet, can consult

anywhere in the world. This

panel, more importantly, are experts

in all things nuclear and have been

game-changers in the nuclear field.

Bringing in the thoriu