Closeout of IE Bulletin 80-25: operating problems with target rock safety-relief valves at boiling water reactors. Final report

During the three-month period beginning July 25, 1980, five events occurred involving two types of malfunctions of Target Rock safety-relief valves at Boston Edison Company's Pilgrim Nuclear Power Station Unit 1. The first three events were caused by direct failures of the valves; the last two events were caused by nitrogen supply system overpressure which led to valve failure. IE Information Notice 80-40 was issued November 7, 1980, to call attention to the two nitrogen overpressure events. As a result of all five events, IE Bulletin 80-25 was issued December 19, 1980, for action to all 30 BWR facilities with operating licenses or near-term operating licenses, and for information only to 24 facilities then under construction. Actions were to be taken with respect to (1) all Target Rock two-stage, pilot-operated safety-relief valves (SRVs), (2) any make or model of SRV which fails to function as designed, excepting for pressure setpoint requirements, and (3) SRV nitrogen/air supply systems. Upon evaluation of utility responses and NRC inspection reports, the bulletin has been closed out for eight of the 30 facilities to which the bulletin was issued for action. For use by NRC/IE, followup items for 22 current facilities with open bulletin status are proposed in Appendix C. Remaining areas of concern and continuing actions dealing with them are described