Technology and Operation - Kernkraftwerk Gösgen

Nuclear fuel cycle
of plutonium which was used in the KKG reactor
in the form of MOX fuel assemblies over
the period 1997 to 2007.
Reprocessing
Irradiated fuel assemblies contain approximately
95 % uranium, 1 % plutonium and
4 % fission products. The precise composition
depends on the discharge burn-up of
the fuel assemblies. During the reprocessing
operation, the structural materials are separated
from the fuel. The fuel is split into uranium,
plutonium and fission products by
chemical means. The extracted energy carriers
of uranium and plutonium are reused in
fuel fabrication and recycled in the reactor.
The fission products are embedded in a glass
matrix, which is then welded into a steel container.
These fission products form the highlevel
waste. The structural materials from the
irradiated fuel assemblies are processed into
intermediate-level waste. Each year, 3.7 cubic
metres of high-level waste and 3 cubic metres
of intermediate-level waste are produced
through the operation of the KKG.
Irradiated fuel assemblies can be disposed of
either with or without reprocessing. Whether
the uranium and plutonium are recycled or
not is subject to political influences. In
Switzerland, for example, a ten-year moratorium
came into effect in 2006 prohibiting the
transport of irradiated fuel assemblies to reprocessing
sites.
Transport of irradiated fuel
assemblies
The transport of irradiated fuel assemblies
and other radioactive materials is subject to
statutory regulations, which are based on
recommendations issued by the International
Atomic Energy Agency (IAEA). The regulations
are designed to protect people and the environment
from harmful radiation and to protect
the material being transported from external
impacts. In the case of irradiated fuel
assemblies that are being transported to a reprocessing
site or to an interim storage facility,
the requisite protection is provided by
transport casks which constitute a radiation
shield. Prior to certification, proof must be
submitted of the fact that the casks can withstand
the most severe of accident scenarios
and remain completely tight.
Interim storage
The Central Interim Storage Facility in Würenlingen
(ZZL) can take high-level, intermediate-level
and low-level radioactive waste. This
also includes the vitrified high-level and intermediate-level
waste from reprocessing
and from irradiated fuel assemblies from the
nuclear power plants. Prior to transfer into a
final repository, all high-level waste needs to
be placed in interim storage (i.e. cooled) for
30 to 40 years on purely physical grounds in
order to remove decay heat. The ZZL has sufficient
capacity for an even longer period of
storage.
Geological repository
After more than 30 years of investigations
and research, comprehensive knowledge and
a basis for decision-making have now been
acquired for the establishment of repositories
in deep geological formations that are required
for radioactive waste. At the end of
June 2006, the Federal Council approved the
«Demonstration of Disposal Feasibility» for
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