Development of Standardized Probabilistic Risk Assessment Models forShutdown Operations Integrated in SPAR Level 1 Model

摘要

Nuclear plant operating experience and several studies show that the risk from shutdownoperation during Modes 4, 5, and 6 at pressurized water reactors and Modes 4 and 5 at boiling waterreactors can be significant. This paper describes using the U.S. Nuclear Regulatory Commission'sfull-power Standardized Plant Analysis Risk (SPAR) model as the starting point for development ofrisk evaluation models for commercial nuclear power plants. The shutdown models are integratedwith their respective internal event at-power SPAR model. This is accomplished by combining themodified system fault trees from the SPAR full-power model with shutdown event tree logic.Preliminary human reliability analysis results indicate that risk is dominated by the operator's abilityto correctly diagnose events and initiate systems.