Examination of the Emergency Planning Zone (EPZ) using Level 3 PSA Approach with MACCS2

This study introduces a probabilistic approach to examine the adequacy of the plume exposure pathway EPZ. Results of this study showed that 6-mile distance meets the probabilistic criteria for this EPZ. Current regulations in the U. S. (10 miles) or Korea (8-10 km) do provide adequate margin for the plume exposure pathway EPZ. The approach may also be useful for regulatory bodies in developing a common procedure for setting up and optimizing the EPZ, especially in the context that there are currently significant differences in the EPZ size defined in different countries. In the U. S., the emergency planning regulation is codified in 10 CFR 50.47. It requires the establishment of two EPZs around each nuclear power plant (NPP): a plume exposure pathway EPZ and an ingestion exposure pathway EPZ. The basis of emergency planning zone (EPZ) was examined in detail in the NUREG-0396 (1978). The existing EPZs determination in the U. S. is based on dose calculations using the 'Reactor Safety Study' WASH 1400 (1975) sequence probabilities and source terms. Since the WASH 1400 study, understanding of severe accident behaviors has improved. Furthermore, many enhancements have been applied to safety features and procedures in modern NPPs. The purpose of this study is to examine the adequacy of current plume exposure pathway EPZ concept using probabilistic safety assessment (PSA) and the MELCOR Accident Consequence Code System 2 (MACCS2). A case study is performed for a Korean Standardized Nuclear Plant (KSNP), which is two loop plant of 2826 MWt, with the assumption that it is located at Kori site. Realistic evaluation based on best estimate approach is important for the correct characterization of risk