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Title: Analysis of Loss-of-Offsite-Power Events 1998–2013

Loss of offsite power (LOOP) can have a major negative impact on a power plant’s ability to achieve and maintain safe shutdown conditions. Risk analyses suggest that loss of all alternating current power contributes over 70% of the overall risk at some U.S. nuclear plants. LOOP event and subsequent restoration of offsite power are important inputs to plant probabilistic risk assessments. This report presents a statistical and engineering analysis of LOOP frequencies and durations at U.S. commercial nuclear power plants. The data used in this study are based on the operating experience during calendar years 1997 through 2013. Frequencies and durations were determined for four event categories: plant-centered, switchyard-centered, grid-related, and weather-related. The emergency diesel generator failure modes considered are failure to start, failure to load and run, and failure to run more than 1 hour. The component reliability estimates and the reliability data are trended for the most recent 10-year period while yearly estimates for reliability are provided for the entire active period. No statistically significant trends in LOOP frequencies over the 1997–2013 period are identified. There is a possibility that a significant trend in grid-related LOOP frequency exists that is not easily detected by a simple analysis. Statisticallymore » significant increases in recovery times after grid- and switchyard-related LOOPs are identified.« less
  1. Idaho National Lab. (INL), Idaho Falls, ID (United States). Risk Assessment and Management Services Dept.
Publication Date:
OSTI Identifier:
Report Number(s):
DOE Contract Number:
AC07-05ID14517; NRC-HQ-14-D-0018
Resource Type:
Technical Report
Research Org:
Idaho National Lab. (INL), Idaho Falls, ID (United States)
Sponsoring Org:
USDOE; US Nuclear Regulatory Commission (NRC)
Country of Publication:
United States
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION duration; frequency; loss of offsite power; operating experience