Calculation analysis of a severe accident at a nuclear power plant with a sodium-cooled fast reactor

The article represents an approach used at the IPPE JSC to the computational analysis of a severe accident caused by a complete cessation of the system and emergency power supply at a nuclear power plant with a sodium-cooled fast reactor. The analysis starts with the initial event and ends with the calculation of the radiation dose to the population. The used codes and methods, the development of the accident, and its consequences are described. The COREMELT code simulating thermal-hydraulic and neutron-physical processes in fast reactors was used to determine the scale of the core destruction. The accumulation of fission products in the fuel is calculated by the SKIF 1.0 code; their release to the gas volumes of fuel elements, to the coolant during the depressurization of fuel elements, and then to the gas cavity of the reactor is determined methodically (in the future, it is planned to use the Alpha‑M code). The transfer through the gas system is calculated by the COREMELT gas module. The activity of fission products released into the environment is methodically assessed (in the future, it is planned to use the KUPOL-BR code). The VYBROS-BN code was used to determine the radiation dose to the population. According to the performed calculation analysis, despite the significant destruction of the core, the dose load to the population at the border of the zone will not exceed the standards.