Performance and Unavailability Analysis of RPS/ESFAS in Korea Standard Nuclear Power Plant (KSNPP)

The safety-related performance analysis of plant protection system (PPS) comprising reactor protection system/engineered safety features actuation system (RPS/ESFAS) was performed from the operating experience of the Korean standard nuclear power plant (KSNPP). The PPS operational data was collected from the trouble reports (TR) to record details of test and maintenance activities at sites. The total operating experience of 8.63 commercial reactor years at four units during the period 1995 through 2000 was studied. The system unavailability analysis was also performed through the detailed fault tree models, using plant specific data based on observed operational experience. Estimated were the unavailabilities on 11 automatic trip parameters for the RPS and 6 signals for the ESFAS. Results of the data analysis and system unavailability were close to ones published for other CE-supplied plants, though this study included a lot of failures occurred in the beginning periods of commercial operation without percolation. This study was performed to provide technical basis for risk-informed applications like technical specification improvement.