NUREG/CR-6928
INL/EXT-06-11119Idaho National Laboratory
U.S. Nuclear Regulatory Commission
Office of Nuclear Regulatory Research
Washington, DC 20555-0001Prepared by: S.A. Eide, T.E. Wierman, C.D. Gentillon, D.M. Rasmuson, C.L. Atwood
NRC Job Code Y6546
2007This report characterizes current industry-average performance for components and initiating events at U.S. commercial nuclear power plants. Studies have indicated that industry performance has improved since the 1980s and early 1990s, so the characterization of current industry-average performance is an important step in maintaining up-to-date risk models. Four types of events are covered: component unreliability (e.g., pump fail to start or fail to run), component or train unavailability resulting from test or maintenance outages, special event probabilities covering operational issues (e.g., pump restarts and injection valve re-openings during unplanned demands), and initiating event frequencies. Typically data for 1998–2002 were used to characterize current industry-average performance, although many initiating events required longer periods (ending in 2002) to adequately characterize frequencies. Results (beta distributions for failure probabilities upon demand and gamma distributions for rates) are used as inputs to the U.S. Nuclear Regulatory Commission standardized plant analysis risk (SPAR) models covering U.S. commercial nuclear power plants.
