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Accession Number DE14-1129950
Title Analysis of Loss-of-Offiste-Power Events 1998-2012.
Publication Date Oct 2013
Media Count 48p
Personal Author T. E. Wierman
Abstract Loss of offsite power (LOOP) can have a major negative impact on a power plants ability to achieve and maintain safe shutdown conditions. Risk analyses performed 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 from fiscal year 1998 through 2012. Frequencies and durations were determined for four event categories: plantcentered, switchyard-centered, grid-related, and weather-related. The EDG 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. A statistically significant increase in industry performance was identified for plant-centered and switchyard-centered LOOP frequencies. There is no statistically significant trend in LOOP durations.
Keywords Failures
Loss of offsite power(LOOP)
Nuclear power plants
Performance evaluation
Power losses
Reactor safety
Reactor shutdown
Risk analysis
Statistical data

Source Agency Technical Information Center Oak Ridge Tennessee
NTIS Subject Category 77H - Reactor Engineering & Nuclear Power Plants
Corporate Author Idaho National Laboratory, Idaho Falls, ID. Risk Assessment and Management Services Department.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1422
Contract Number N/A

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