United States Nuclear Regulatory Commission - Protecting People and the Environment
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Industry Average Parameter Estimates

NUREG/CR-6928 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. The document is titled "Industry-Average Performance for Components and Initiating Events at U.S. Commercial Nuclear Power Plants" (NUREG/CR-6928).

The Data Sheets are shown to provide direct access to each parameter estimate. These data sheets are originally from NUREG/CR-6928. When the date in the footer of the data sheet is later than February 2007 (the publishing date of NUREG/CR-6928), that data sheet has been updated and supercedes the NUREG/CR-6928 parameter estimates. In addition, a spreadsheet with the summary tables in NUREG/CR-6928 is available for download.

Current Results:

Summary Detailed Data Sheets

Historical Results:

Summary Detailed Data Sheets
Page Last Reviewed/Updated Thursday, April 14, 2016