The preliminary PSA is carried out through I ) exhaustive identification of potential abnormal events and II ) efficient screening of those events using a risk matrix. In the detailed PSA, III ) Accident scenario analysis is carried out to analyze causes and event sequences of each abnormal event by drawing a fault tree (FT) and event tree (ET) respectively. IV ) Accident frequencies are evaluated by quantifying FT and ET. Finally, V ) radioactive material releases to the environment are evaluated as the accident consequence using a five factor formula calculating the release amount from five material-specific factors.