Operating experience feedback report -- Pressure locking and thermal binding of gate valves. Commercial power reactors: Volume 9

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

OSTI ID:10143999

Hsu, C

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.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (United States). Div. of Safety Programs
• Sponsoring Organization: Nuclear Regulatory Commission, Washington, DC (United States)
• OSTI ID: 10143999
• Report Number(s): NUREG--1275-Vol.9; AEOD/S--92-07; ON: TI93010505
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210100
210200
22 GENERAL STUDIES OF NUCLEAR REACTORS
220900
AFTER-HEAT REMOVAL
BWR TYPE REACTORS
CONTAINMENT SPRAY SYSTEMS
ENGINEERED SAFETY SYSTEMS
FAILURES
LOW PRESSURE COOLANT INJECTION
POWER REACTORS
NONBREEDING
LIGHT-WATER MODERATED
BOILING WATER COOLED
POWER REACTORS
NONBREEDING
LIGHT-WATER MODERATED
NONBOILING WATER COOLED
PRESSURE EFFECTS
PWR TYPE REACTORS
REACTOR SAFETY
RECOMMENDATIONS
TEMPERATURE EFFECTS
VALVES