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Title Operating experience feedback report -- Pressure locking and thermal binding of gate valves. Commercial power reactors: Volume 9
Creator/Author Hsu, C.
Publication Date1993 Mar 01
OSTI IdentifierOSTI ID: 10143999; Legacy ID: TI93010505
Report Number(s)NUREG--1275-Vol.9; AEOD/S--92-07
Other Number(s)Other: ON: TI93010505
Resource TypeTechnical Report
Resource RelationOther Information: PBD: Mar 1993
Research OrgNuclear Regulatory Commission, Washington, DC (United States). Div. of Safety Programs
Sponsoring OrgNuclear Regulatory Commission, Washington, DC (United States)
Subject22 GENERAL STUDIES OF NUCLEAR REACTORS; 21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; BWR TYPE REACTORS; VALVES; PWR TYPE REACTORS; FAILURES; AFTER-HEAT REMOVAL; LOW PRESSURE COOLANT INJECTION; RECOMMENDATIONS; CONTAINMENT SPRAY SYSTEMS; REACTOR SAFETY; ENGINEERED SAFETY SYSTEMS; PRESSURE EFFECTS; TEMPERATURE EFFECTS
Description/Abstract The potential for valve inoperability caused by pressure locking and thermal binding has been known for many years in the nuclear industry. Pressure locking or thermal binding is a common-mode failure mechanism that can prevent a gate valve from opening, and could render redundant trains of safety systems or multiple safety systems inoperable. In spite of numerous generic communications issued in the past by the Nuclear Regulatory Commission (NRC) and industry, pressure locking and thermal binding continues to occur to gate valves installed in safety-related systems of both boding water reactors (BWRs) and pressurized water reactors (PWRs). The generic communications to date have not led to effective industry action to fully identify, evaluate, and correct the problem. This report provides a review of operating events involving these failure mechanisms. As a result of this review this report: (1) identifies conditions when the failure mechanisms have occurred, (2) identifies the spectrum of safety systems that have been subjected to the failure mechanisms, and (3) identifies conditions that may introduce the failure mechanisms under both normal and accident conditions. On the basis of the evaluation of the operating events, the Office for Analysis and Evaluation of Operational Data (AEOD) of the NRC concludes that the binding problems with gate valves are an important safety issue that needs priority NRC and industry attention. This report also provides AEOD`s recommendation for actions to effectively prevent the occurrence of valve binding failures.
Country of PublicationUnited States
LanguageEnglish
FormatSize: 29 p.
AvailabilityOSTI; NTIS; INIS; GPO
System Entry Date2005 Jul 05

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