Radiation risk assessment for nuclear power plant staff in different emergency situations

The paper presents the results of radiation risk assessment for the staff of a nuclear power plant design during design basis accident (spent nuclear fuel assembly falling on fuel in reactor core or storage pool during refueling operations) and a beyond design basis accident (large leakage of the primary coolant with failure of the active part of the emergency cooling system and complete blackout for 24 h). The assessment is based on state-of-the-art radiation risk models from the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and the International Commission on Radiological Protection (ICRP). The calculation of risk indicators for occupational exposure of NPP staff in emergency situations was carried out on the basis of data obtained using a computational module created in the COMSOL 5.6 multiphysics software, doses from a radioactive cloud and internal exposure due to inhalation for such radionuclides as 134Cs, 137Cs, 131I, 133I, 90Sr. A feature of this approach is the detailed consideration of the NPP industrial site infrastructure, which allows obtaining a more accurate assessment of the radionuclide air distribution and fallout.