atw - International Journal for Nuclear Power | 10.2020

atw Vol. 65 (2020) | Issue 10 ı October
ENVIRONMENT AND SAFETY 492
Nuclear Energy – Reliable, Safe,
Economical and Always Available
to Protect the Environment
Peter Dyck
Introduction The commercial use of nuclear energy (NE) was initially linked to the great expectation of generating
enormous quantities of cheap electricity. Various technologies were therefore developed, starting with reactors based
on natural uranium. Many countries, however, concentrated on reactors with enriched uranium to achieve even higher
power densities. Nuclear power plants worldwide were designed and constructed on this basis. At that time in Germany,
for example, the SPD in particular campaigned for around 50 nuclear power plants.
Mainly in western countries, the
emphasis was placed on high safety
standards from the very outset. As
time went by these standards were
raised higher and higher. Naturally,
the consequence was further increases
in specific costs. Increasing the capacity
and thus the size of the plants was
seen as an initial solution to reducing
them. There were also repeated
demands for inherently safe plants.
Different approaches and concepts,
such as Generation III, Generation
III+ and Generation IV, brought this
goal closer and closer.
In the 2000s, the construction
of new nuclear power plants was also
influenced by another aspect, namely
the reduction of CO 2 emissions from
electricity generation. The reason for
this was the conviction that CO 2
released by humans would contribute
massively to global warming. It quickly
became clear, however, that the socalled
renewable energies (wind and
solar energy), which were promoted
from 2000 onwards, could only supply
weather-dependent power and were
not sustainable with respect to the
entire electricity system. Permanent
back-up provided by fossil fuel or
nuclear power are required. In
Germany, these back-up systems were
made more expensive due to the
prio ritization rule of the Renewable
Energy Sources Act. The renewable
energies were unable to contribute to
grid stability, not to mention the costs.
It is therefore impossible to provide a
secure power supply for industrialized
countries with wind turbines (off and
on-shore) and photovoltaic installations.
These and other serious disadvantages
were the trigger that
brought the focus of interest in various
countries firmly back to nuclear
energy.
SMRs (small modular reactors,
Generation IV) are now being developed
as a near inherently safe design
concept for small countries and a
decentralized power supply. They
include gas-cooled (He) reactors with
up to 300 MW installed capacity. The
idea is based on a uniform design, a
standard approval procedure and
standardized components, combined
with a reduction in costs. In each case,
the plants can be adjusted to the
demand (electricity, sea water desalination,
process heat) by constructing
several modules. They would be
particularly suitable for use in
combination with renewable energies
as they can be switched on and off
quickly.
The dual fluid reactor (DFR) is
emerging as a new development. This
reactor works with a liquid fuel
mixture and a metal coolant. As a fast
breeder reactor, it can fission all
uranium and plutonium isotopes as
well as all transuranic elements and
breed fissile material. In each case, the
fission products are separated and
sent for ultimate waste disposal, while
transmutation is still carried out for a
number of isotopes. This results in
significantly lower requirements for
the proof of long-term safety of a deep
geological repository of some 500 to
1,000 years instead of one million
years. In this way, it is also possible to
use spent nuclear fuels from light
water reactors (LWR). As a result, an
enormous amount of fissile material
is available, especially since Th-232
could also be used. The policy adopted
by many countries of choosing longterm
interim storage for their spent
fuel assemblies is now proving to have
been right.
Current situation
A number of the many nuclear power
plants that were built in the early
years have already ceased operation.
Either because the design or size of
the plant did not meet economic
requirements, or because technical
problems made decommissioning
appear advisable, or because the plant
had simply reached the end of its
service life.
The reactor accidents of Three
Mile Island (1979, in Block II) and
Chernobyl (1986, Block IV), which
resulted in the decommissioning of
nuclear power plants, had an additional
impact. In Italy, it was even
decided to abandon the nuclear
energy supply completely.
Further shutdowns followed the
tsunami in Japan due to the problems
associated with it, such as failure of
the electricity supply and oxyhydrogen
gas explosions in the old,
poorly secured Fukushima reactors.
Thereupon, in Germany, for example,
eight reactors were forced to shut
down for political reasons. At the
same time, the decision was also
taken to phase out nuclear energy
completely by 2022. The three most
modern rectors Isar 2, Emsland and
Neckarwestheim 2 will be shut down
for decommissioning at the end of
2022. In other countries, on the other
hand, safety systems were reassessed
and, where necessary, upgraded.
With its “international best practices
in the ageing management of
nuclear power plants”, the International
Atomic Energy Agency (IAEA)
supports its member states in extending
the service life of nuclear power
plants by a further 20 to 40 years
while continuing to guarantee the
highest possible level of safety. [1]
The IAEA coordinates collaboration
between the member states in order to
adopt best practices. The program
deals with the physical aging of
systems, structures and components
as well as technical progress. It also
incorporates the results of the Electric
Power Research Institute (EPRI),
which cooperates with the IAEA.
Recently, however, new nuclear
power plants have been commissioned
Environment and Safety
Nuclear Energy – Reliable, Safe, Economical and Always Available to Protect the Environment ı Peter Dyck