Accident Scenario Analysis for Beyond-design Basis External Hazards Based on the PSA Model

Nuclear power plants in Korea are mostly located along the coastal areas, and can be affected by external hazards caused by typhoons such as high wind or external flooding. In addition, the intensity of typhoons in Korea is predicted to increase due to climate change and the possibility of external hazards exceeding design basis is also expected to increase. Therefore, it is necessary to review the plant risk against beyond-design basis external hazards. This study aims to investigate the accident scenarios caused by high wind hazard and external flooding hazard caused by typhoon. In addition, we calculate the conditional probability of core damage for each accident scenario to determine the possibility of core damage resulting from external hazards using the probabilistic safety assessment (PSA) model. By focusing on the derived accident scenarios and their results presented here, it is expected that the plant safety against external hazards can be evaluated more efficiently.

Keywords: Probabilistic safety assessment, beyond-design basis external hazard, high wind, external flooding, accident scenario analysis.