Development of Probabilistic Risk Assessment Model for BWR Shutdown Modes 4 and 5 Integrated in SPAR Model

摘要

Nuclear plant operating experience and several studies show that the risk from shutdown operation during modes 4, 5, and 6 can be significant in commercial light water reactors. This paper describes development of the standard template risk evaluation models for shutdown modes 4 and 5 for commercial boiling water nuclear power plants (BWR). The shutdown probabilistic risk assessment model uses full power Nuclear Regulatory Commission's (NRC's) Standardized Plant Analysis Risk (SPAR) model as the starting point for development. The shutdown PRA models are integrated with their respective internal events at-power SPAR model. This is accomplished by combining the modified system fault trees from SPAR full power model with shutdown event tree logic. For human reliability analysis (HRA), the SPAR HRA (SPAR-H) method is used which requires the analysts to perform a task analysis and complete worksheet to assign the performance shaping factors (PSFs). The results are then used to estimate HEP of interest.