Common-Cause Component Group Modeling Issues in Probabilistic Risk Assessment

摘要

Common cause failures (CCFs) have been recognized as significant risk contributors in probabilistic risk assessments (PRAs) for commercial nuclear power plants (NPPs) since the 1980s. A series of reports including those of United States Nuclear Regulatory Commission (NRC) have been published from the late 1980s to early 2000s to provide guidelines for performing CCF event data analysis and modeling CCF in PRA. NUREG/CR-4780 [1] presented the framework for including CCFs in risk and reliability evaluations and provided procedures to perform and document CCF analysis with a practical and systematic approach. NUREG/CR-5485 [2] provided a set of guidelines to help PRA analysts in modeling CCF events in commercial NPPs. NUREG/CR-6268, Revision 1 [3] provided guidance for collecting, classifying, and coding CCF events. It also described the impact vector and mapping method used in the CCF software system to estimate CCF parameters. NUREG/CR-5497 [4] provided the CCF parameter estimates for the majority of the risk important safety systems and components in commercial NPPs.