05000298/LER-2010-001, Regarding Technical Specification Prohibited Condition Due to Safety Relief Valve Test Failures
| ML100700590 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 03/05/2010 |
| From: | Dori Willis Nebraska Public Power District (NPPD) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NLS2010021 LER 10-001-00 | |
| Download: ML100700590 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| 2982010001R00 - NRC Website | |
text
N Nebraska Public Power District "Always there when you need us" NLS2010021 March 5, 2010 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001
Subject:
Licensee Event Report No. 2010-001-00 Cooper Nuclear Station, Docket No. 50-298, DPR-46
Dear Sir or Madam:
The purpose of this correspondence is to forward Licensee Event Report 2010-001-00.
Sincerely, Demetrius L. Wi.
General Manager of Plant Operations
/bk Attachment cc:
Regional Administrator w/attachment USNRC - Region IV Cooper Project Manager w/attachment USNRC - NRR Project Directorate IV-1 Senior Resident Inspector w/attachment USNRC - CNS SRAB Administrator w/attachment NPG Distribution w/attachment INPO Records Center w/attachment SORC Chairman w/attachment CNS Records w/attachment COOPER NUCLEAR STATION P.O. Box 98 / Brownville, NE 68321-0098 Telephone: (402) 825-3817 / Fax: (402) 825-5211 wvw'npod.com 0 k R_
Abstract
On January 12, 2010, two of eight Target Rock safety relief valve (SRV) pilot valve assemblies, removed during refueling outage 25, failed to lift within Technical Specification (TS) lift setpoint requirements. Wyle Laboratories, Inc. performed this testing. The pressure setpoint for the first pilot assembly is 1100 +/- 33.0 psig; the SRV pilot assembly lifted at 1166 psig. The pressure setpoint for the second pilot assembly is 1090 +/- 32.7 psig; it lifted at 1139 psig. Two subsequent informational lifts were performed for both SRV pilot assemblies and were within the TS pressure setpoint tolerances.
Cooper Nuclear Station (CNS) was in Mode 1, Power Operation, at approximately 74% power at the time of the discovery. The remaining SRV and SRV pilot valve assemblies tested satisfactory for TS lift setpoint requirements.
The cause is the same as previously reported in Licensee Event-Report 2008-002-00, pilot disc-to-seat corrosion bonding. The performance of the two-stage Target Rock pilot-actuated valves in the current design application at CNS is unsuccessful in consistently meeting the as-found lift test requirements. CNS is pursuing corrective actions to evaluate and revise the as-found test requirements contained within TS.
This event is reportable as a condition prohibited by TS. The event has negligible safety significance.
NRC FORM 366 (9-2007)
(If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of Form 366A)
CORRECTIVE ACTIONS
CNS has not fully implemented the corrective actions reported in LER 2008-002-00. They are being tracked in the CNS corrective action program as follows:
- 1. Prepare a design document to determine how many of the eight SRVs must function to ensure plant safety.
- 2. Prepare and submit a TS license amendment request to allow one or two SRV failures during the SRV as-found TS lift testing as determined by the approved design document.
Based on the test evidence, past evaluations of the failure mechanism, and corrective actions currently in process, no additional corrective actions are required.
PREVIOUS EVENTS LER 2008-002 On July 7 through July 9, 2008, the results of Target Rock SRV test data performed at Wyle Laboratories identified that one of eight SRV pilot assemblies failed as-found pressure setpoint testing. The SRV pilot assembly lifted at 1165 psig, outside its TS setpoint tolerance of 1100 +/- 33.0 psig. The mechanistic cause was pilot disc-to-seat corrosion bonding between the Stellite 21 pilot disc and Stellite 6B pilot body seat to cause the SRV pilot assembly to lift outside its TS setpoint tolerance.
LER 2007-002 On February 28 through March 2, 2007, the results of Target Rock SRV tests performed at Wyle Laboratories identified that one of eight SRV pilot valve assemblies failed to lift within its TS lift setpoint of 1090 +/- 32.7 psig. The failure was a result of sufficient corrosion bonding between the SRV pilot valve assembly Stellite 21 disc and the pilot valve Stellite 6B body seat to cause the SRV pilot valve to lift outside its TS setpoint tolerance.
LER 2005-002 On May 16 and May 19, 2005, a review of Target Rock SRV test data, provided by Wyle Laboratories, determined that three of eight SRV pilot valve assemblies failed to lift within their TS lift setpoint. Examination determined that sufficient corrosion bonding existed between the SRV pilot valve assembly Stellite 21 disc and the pilot valve Stellite 6B in-body seat to cause the SRV pilot valves to lift outside TS setpoint tolerances.
LER 2003-002 On May 19, 2003, a review of Target Rock SRV test data, provided by Wyle Laboratories, determined that four of eight SRV pilot valve assemblies failed to lift within their TS lift setpoint. Examination determined that sufficient corrosion bonding existed between the SRV pilot valve assembly Stellite 21 disc and the pilot valve Stellite 6B in-body seat to cause the SRV pilot valves to lift outside TS setpoint tolerances.
ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS© 4 ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS© 4
Correspondence Number: NLS2010021 The following table identifies those actions committed to by Nebraska Public Power District (NPPD) in this document. Any other actions discussed in the submittal represent intended or planned actions by NPPD. They are described for information only and are not regulatory
commitments
Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.
COMMITMENT
COMMITTED DATE
COMMITMENT
NUMBER OR OUTAGE None 4
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I 4
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