Beaver Valley: Residual Heat Removal System Piping Leak

Event Number: 46304
Facility: BEAVER VALLEY
Event Date: 10/02/2010

RESIDUAL HEAT REMOVAL SYSTEM PIPING LEAK

"Approximately five hours after Beaver Valley Power Station Unit No. 1 was shutdown at 0011 hours [EDT] to enter a scheduled refueling outage, an approximate 5 drops per minute leak was identified from a drain valve on the Residual Heat Removal (RHR) System inside containment. This leak is downstream of the two series RHR isolation valves on a pipe which connects to both trains of RHR. The actual location of the leak on the valve was not immediately evident. An evaluation was requested. At 1011 hours, the evaluation reported a 270 degree circumferential crack in the socket weld on the RHR side of the valve. Without reasonable assurance of RHR System operability, both trains of RHR were declared inoperable. Both trains of the RHR System are currently in service, along with three steam generators/condenser remaining available for decay heat removal. Actions to address this condition are being pursued.

"This is being reported as a condition that at the time of discovery could have prevented the fulfillment of the safety function of systems needed to remove decay heat pursuant to 10 CFR 50.72(b)(3)(v)(B) since both trains of RHR were declared inoperable.

"Beaver Valley Power Station Unit No. 2 is unaffected by this event and remains at 100 percent power.

"The NRC Resident Inspector has been notified."

T.S. Action 3.4.7 requires that efforts be immediately initiated to restore RHR as soon as possible.