SUMMARY OF A STUDY OF AIR-OPERATED VALVES IN U. S. NUCLEAR POWER PLANTS, NUREG/CR-6654 (INEEL/EXT-98-00383)

摘要

The NRC, with assistance from the INEEL, studied the design, qualification, operation, maintenance, and testing of air-operated valves (AOVs) in commercial nuclear power plants. The goal was to help the NRC determine if and how the NRC needs to focus additional attention on the design, qualification, applications, testing (initial and in-service), and/or maintenance of AOVs in order to reduce plant vulnerabilities associated with individual or common-cause failures. Design, qualification, applications, maintenance, and testing of AOVs were studied in relation to their safety significance in nuclear power plant applications. Seven nuclear plant sites were visited as part of this study. Design requirements for AOVs were identified. Events were selected and analyzed to determine important issues. Risk studies were conducted and analyzed. Previous and ongoing work of licensees and other nuclear industry organizations were studied. Issues and events regarding pneumatic systems, solenoid operators, common-cause failures, etc. were examined. Conclusions and remarks about the safety-significance of issues involving AOVs were offered. References, a tabulation of AOV populations, tabulation of events, a listing of NRC generic communications, results of significance analyses (ASP), trip reports, and comment summaries were included in the tables and appendices in NUREG/CR-6654.