Technical Specification action statements requiring shutdown. A risk perspective with application to the RHR/SSW systems of a BWR

Technical Report · Mon Nov 01 04:00:00 EST 1993

DOI:https://doi.org/10.2172/10106753· OSTI ID:10106753

Mankamo, T ^[1]; Kim, I S; Samanta, P K ^[2]

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1. Avaplan Oy, Espoo (Finland)
2. Brookhaven National Lab., Upton, NY (United States)

When safety systems fail during power operation, the limiting conditions for operation (LCOs) and associated action statements of technical specifications typically require that the plant be shut down within the limits of allowed outage time (AOT). However, when a system needed to remove decay heat, such as the residual heat removal (RHR) system, is inoperable or degraded, shutting down the plant may not necessarily be preferable, from a risk perspective, to continuing power operation over a usual repair time, giving priority to the repairs. The risk impact of the basic operational alternatives, i.e., continued operation or shutdown, was evaluated for failures in the RHR and standby service water (SSW) systems of a boiling-water reactor (BWR) nuclear power plant. A complete or partial failure of the SSW system fails or degrades not only the RHR system but other front-line safety systems supported by the SSW system. This report presents the methodology to evaluate the risk impact of LCOs and associated AOT; the results of risk evaluation from its application to the RHR and SSW systems of a BWR; the findings from the risk-sensitivity analyses to identify alternative operational policies; and the major insights and recommendations to improve the technical specifications action statements.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (United States). Div. of Systems Research; Avaplan Oy, Espoo (Finland); Brookhaven National Lab., Upton, NY (United States)
• Sponsoring Organization: Nuclear Regulatory Commission, Washington, DC (United States)
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 10106753
• Report Number(s): NUREG/CR--5995; BNL-NUREG--52364; ON: TI94003823
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210100
22 GENERAL STUDIES OF NUCLEAR REACTORS
220900
AFTER-HEAT REMOVAL
BWR TYPE REACTORS
ENGINEERED SAFETY SYSTEMS
FAILURES
HEAT TRANSFER
HYDRAULICS
POWER REACTORS
NONBREEDING
LIGHT-WATER MODERATED
BOILING WATER COOLED
REACTOR COOLING SYSTEMS
REACTOR SAFETY
RISK ASSESSMENT
SENSITIVITY ANALYSIS