Methodologies for determination activation of steel components and concrete structures of WWER-440 type nuclear power plants
23rd Symposium of AER on VVER Reactor Physics and Reactor Safety (2013, Štrbské Pleso, Slovakia)
Spent fuel storage and disposal
Abstract
Preliminary decommissioning plans constitute vital parts of the licensing
documentation of nuclear power plants. On the other hand, a reasonable estimate of the
amount and radiological characteristics of the radioactive waste born during the operational
life of a power plant is crucial. Since the largest activities are created by neutron activation,
the characteristics of the activated waste materials, such as mass, volume, specific activities
by isotopes and waste index, should be estimated in advance as accurately as possible in order
to assess the waste repository requirements of an NPP. The cost issues related to waste
disposal are huge. Therefore, inadequate planning of the volume and mass of low,
intermediate and high level waste types can result in financial problems.
The present paper describes the methodology applied for determination of neutron
induced activation of steel components and concrete structures surrounding VVER 440 type
reactor cores and the general results which were obtained from the above mentioned two
projects. According to related international literature and studies performed earlier by the
authors, the vast majority (usually exceeding 99%) of the radioactive inventory present at the
time of final shutdown of a nuclear power plant is concentrated in the materials directly
surrounding the reactor core. In these regions, the predominant evolution of radionuclides is
upon neutron induced nuclear reactions. This report is not aimed at the assessment of the
radioactive inventory produced by contamination of NPP components (such as steam
generators and pipelines etc.), only the relevant radioactive waste characteristics of the
activated steel and concrete structures are calculated and summarized.