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| Entered date | Event description | |
|---|---|---|
| ENS 42459 | 31 March 2006 16:01:00 | In accordance with 10 CFR 21.21(d)(1), Pacific Gas and Electric (PG&E) is hereby notifying the NRC of a defective component received from Flowserve, Flow Control Division, in Raleigh, NC, but not installed at Diablo Canyon Power Plant (DCPP). The component is an 8-inch tilting disk check valve that was procured for installation in the Residual Heat Removal (RHR) System during the Unit 2 refueling outage (2R13) scheduled to begin on 04/17/06. On 03/02/06, the defect was identified at DCPP during post-receipt bench testing and involved incorrect disc dimensions that caused the disc to stick in the valve bonnet (i.e., in the open position). This would have prevented the valve from performing its intended safety function of closing to prevent pump-to-pump interaction when both RHR pumps are running. (These check valves were installed in response to NRC Bulletin 88-04, 'Potential Safety Related Pump Loss.') Failure of this check valve, had it been installed, could have resulted in the loss of one RHR train on Unit 2, which could impact the ability to shut down the reactor and maintain it in a safe shutdown condition. On 03/08/06, PG&E notified Flowserve of the defect via Supplier Audit Finding Report #060670010 and requested corrective actions be taken. On 03/13/06, Flowserve concluded that the defect was caused by disc design error and test procedure error. On 03/16/06, Flowserve initiated Quality Problem Corrective Action Plan #169, in which they concluded a Part 21 evaluation was not required. On 03/31/06, PG&E Vice President, Diablo Canyon Operations and Station Director, (deleted), determined that the defect met 10 CFR 21.21 reporting requirements. PG&E initiated purchase of the 600 lb, stainless steel check valve on 06/02/05, and does not know whether any others have been manufactured by Flowserve. The valve was manufactured in accordance with Vendor Assembly Drawing W9023267 and ASME Section III, Subsection NC, 1989 Edition. PG&E subsequently repaired the check valve in accordance with instructions provided in a Flowserve letter to PG&E, dated 03/16/06. The valve has passed inspection and bench testing and will be installed during 2R13. The licensee notified the NRC Resident Inspector. |