United States Nuclear Regulatory Commission - Protecting People and the Environment

Reliability Study: Babcock & Wilcox Reactor Protection System, 1984–1998 (NUREG/CR-5500, INEL/EXT-97-00740, Volume 11)

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Publication Information

Manuscript Completed: November 2001
Date Published: November 2001

Prepared by:
Thomas E. Wierman, Scott T. Beck, Michael B. Calley
Steven A. Eide, Cindy D. Gentillon, William E. Kohn

Risk & Reliability Assessment Department
Idaho National Engineering and Environmental Laboratory
P.O. Box 1625
Idaho Falls, Idaho 83415-3850

Prepared for:
Division of Risk Analysis & Applications
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

NRC Job Code Y6214

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This report documents an analysis of the safety-related performance of the reactor protection system (RPS) at U.S. Babcock & Wilcox commercial reactors during the period 1984 through 1998. The analysis is based on the Oconee and Davis-Besse plant designs. RPS operational data were collected for all U.S. Babcock & Wilcox commercial reactors from the Nuclear Plant Reliability Data System and Licensee Event Reports. A risk-based analysis was performed on the data to estimate the observed unavailability of the RPS, based on fault tree models of the systems. An engineering analysis of trends and patterns was also performed on the data to provide additional insights into RPS performance. RPS unavailability results obtained from the data were compared with existing unavailability estimates from Individual Plant Examinations and other reports.

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