atw - International Journal for Nuclear Power | 06/07.2019

atw Vol. 64 (2019) | Issue 6/7 ı June/July
SERIAL | MAJOR TRENDS IN ENERGY POLICY AND NUCLEAR POWER 336
Serial | Major Trends in Energy Policy and Nuclear Power
SMRs – Overview on International
Developments and Safety Features
Andreas Schaffrath and Sebastian Buchholz
1 Introduction
In the last years, several well-developed Small Modular
Reactor (SMR) designs from different international
vendors were announced. SMRs are mainly designated
for deployment not only in sparsely populated remote
areas but also near heavily populated cities and may
provide electricity, district heating and potable water. The
construction and deployment of SMRs is also being
promoted in various European countries (e.g. the UK or
Russia) [BUS-16, WNA-19].
SMRs can satisfy the need for low carbon generation
energy sources and especially the need for new capacities,
since significant (conventional and nuclear) power plant
capacities have to be retired and replaced in the coming
decades. Additionally, many countries see nuclear energy
alongside renewables as a possibility for sustainable
development and a reliable energy system [OZA-19].
Especially for strongly growing developing countries,
SMRs can provide the possibility to establish a nuclear
industry with a fraction of the costs of currently operating
nuclear power plants. These savings result mainly due to
complete prefabrication of modules fully equipped in
factories. This results in high qualities, shorter production
times, lower capital costs, standardization and therefore
lower costs due to mass production, simplification of safety
systems by primarily use of passive systems, lower number
of employees for deploying and removal, the opportunity
to deploy one module after another and higher plant availability
due to modular character. SMRs may also replace
older fossil plants and lead consequently to savings of gas,
oil and other fossil resources [BUS-15, WNA-19].
In chapter 2 of this contribution an overview on current
SMR developments is given. Due to the large number of
designs currently in operation, in construction or under
development, the focus is on identifying general construction
und safety trends. These are discussed in chapter
3. The description of individual details is given below for
illustrative purposes only. For the sake of completeness,
issues such as competitiveness, licensing, position of
selected European decision makers are addressed
additionally. Finally, in chapter 4 an overview of necessary
improvements and validation of the nuclear simulation
chain applied in nuclear licensing procedures is provided.
The improved simulation chain will be used for safety
assessments of SMRs according to the current state of the
art in science and technology.
2 Definitions, history and
current developments
After a compilation of different SMR definitions in section
2.1, a short overview on the history (section 2.2) and
­current projects (section 2.3) is provided. This publication
deals exclusively with SMRs for energy and/or power
generation. Engines for nuclear icebreakers, merchant
vessels and submarines, studies of mobile SMRs, propulsion
systems for outer space, as well as military applications
are not considered here, as this would go far
beyond the scope.
2.1 Definitions
There are two different definitions for SMR in literature.
The first one is widely used in North America (e.g. the USA
and Canada). Here, the abbreviation SMR stands for Small
Modular Reactor. The emphasis of this definition is on the
term modular, which characterises, that a (larger) production
unit can consist of different modules, which may
be added one by one. Also, it is possible to refuel one
module, while the others continue operation. The term
small in the definition SMR characterises an electrical
power output of less than 300 MW e . In this scale the
primary coolant system, selected parts of the secondary
and, where necessary, intermediate circuit and auxiliary
systems can be arranged in an integral reactor pressure
vessel (RPV). An SMR module may be transported to the
construction site in one piece or in few parts [WNA-19].
On the contrary, the IAEA defines SMR as Small
and Medium Sized Reactors. These reactors can have
capacities up to 700 MWe. The modular character is not
met by this definition but is also not excluded [BUS-15].
According to this definition, all reactors ever built in this
power range – even the VVER440s – are SMRs [SCA-19].
Therefore, in the following the focus is on modular SMRs
2.2 History
The idea of small (modular) reactors is not a new one.
Since the mid of the last century the former USSR and the
USA have used SMRs for
pp
energy and heat production of remote areas (e.g. Arctic,
the Antarctica or Greenland) and
pp
engines for their submarines, merchant vessels and ice
breakers [BUS-15].
One well-known example is e.g. the Army Nuclear Power
Program (ANPP) [SUL-90]. Numerous information and
pictures about the ANPP are published on the website
Army Engineer History of the U.S. Army Corps of Engineers
[ARH-171]. The ANPP was supervised by the U.S. Army
Engineer Reactors Group and had it headquarters in Fort
Belvoir (Virginia). Eight nuclear power plants (NPPs) were
built and operated in remote areas. The program ran
from 1954 to 1977, when the last nuclear reactor was
decommissioned. The main tasks were
pp
to carry out research and development in the field of
nuclear power plants together with the Atomic Energy
Commission,
pp
to operate the nuclear power plants of the Corps of
Engineers,
pp
to carry out training measures for the operation of
these nuclear power plants,
pp
to provide technical assistance to other authorities as
needed and
pp
to develop programs for the application of nuclear reactors
for military use.
One peculiarity was the naming of the SMRs. The name
consists of two letters followed by a number and in some
cases a third letter. The first letter indicates whether the
installation is stationary (S), mobile (M) or portable (P),
the second letter whether the power is high (H), medium
Serial | Major Trends in Energy Policy and Nuclear Power
SMRs – Overview on International Developments and Safety Features ı Andreas Schaffrath and Sebastian Buchholz