05000298/LER-2007-002, Re Technical Specification Prohibited Operation Due to Safety Relief Valve Test Failure
| ML071230269 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 04/30/2007 |
| From: | Michael Colomb Nebraska Public Power District (NPPD) |
| To: | Document Control Desk, Plant Licensing Branch III-2 |
| References | |
| NLS2007024 LER 07-002-00 | |
| Download: ML071230269 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| 2982007002R00 - NRC Website | |
text
N Nebraska Public Power District Always there when you need us NLS2007024 April 30, 2007 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001
Subject:
Licensee Event Report No. 2007-002-00 Cooper Nuclear Station, NRC Docket 50-298, DPR-46
Dear Sir or Madam,
The purpose of this correspondence is to forward the enclosed Licensee Event Report.
Sincer Michael J. Colomb General Manager of Plant Operations
/dm Enclosure cc:
Regional Administrator w/enclosure USNRC - Region IV Cooper Project Manager w/enclosure USNRC - NRR Project Directorate IV-1 Senior Resident Inspector w/enclosure USNRC - CNS NPG Distribution w/enclosure INPO Records Center w/enclosure SORC Administrator w/enclosure SRAB Administrator w/enclosure CNS Records w/enclosure COOPER NUCLEAR STATION P.O. Box 98 / Brownville, NE 68321-0098 Telephone: (402) 825-3811 / Fax:. (402) 825-5211 www.nppd.com
ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS@
ATTACHMENT 3 LIST OF REGULATORY COMMITMENTSC Correspondence Number: NLS2007024 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 N/A N/A i -
t t
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4 I PROCEDURE 0.42 REVISION 20 PAGE 18 OF 25 ý
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Abstract
The results of Target Rock safety relief valve (SRV) tests performed on February 28 through March 2, 2007 by Wyle Laboratories, identified that one of eight SRV pilot valve assemblies failed to lift within its Technical Specification (TS) lift set point of 1090 +/- 32.7 psig. The SRV lifted at 1127 psig. The discovery was made as a result of routine TS surveillance testing of pilot valve assemblies removed during Refueling Outage 23. Cooper Nuclear Station (CNS) was in Mode 1 at 100 percent power at the time of the determination. The remaining valves tested within their TS lift set point tolerances.
The failure was a result of sufficient corrosion bonding between the SRV pilot valve assembly Stellite 21 disc and the pilot valve Stellite 6 body seat to cause the SRV pilot valve to lift outside TS set point tolerances. As documented in CNS Licensee Event Report 2005-002-00, this is a recurring problem at CNS and in the industry. The valves were replaced with tested spare valves certified to lift within 1% of set point.
This event is considered to have no safety significance and has no impact on the reactor pressure vessel pressure relief function capability.
NRC FORM 366 (6-2004)
(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 ACTION
The corrective action identified in CNS LER 2003-002, to replace the SRV pilot valve assemblies with certified pilot valve assemblies containing Stellite 21 pilot discs and Stellite 6 pilot body seals, has been fully implemented during RFO 21. The corrective actions identified in CNS LER 2005-002, to implement appropriate elements of the Target Rock Users Group industry best practices for refurbishment on each refurbishment, including installation of a new Stellite 21 pilot disc during each refurbishment, and to have a CNS Engineering representative present during refurbishment of each SRV, had not been fully applied to pilot assembly 383 prior to its installation during RFO 22 for Cycle 23. However, it is part of the population of pilot valve assemblies, sent to the vendor for refurbishment following RFO 23, which will undergo these
corrective actions
The corrective actions represent an ongoing effort for future SRV pilot valve refurbishments.
Based on the test evidence, the evaluation of the failure mechanism, and the corrective actions currently in place, no additional corrective actions are required.
PREVIOUS EVENTS 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 set point. Examination determined that sufficient corrosion bonding existed between the SRV pilot valve assembly Stellite 21 disc and the pilot valve Stellite 6 in-body seat to cause the SRV pilot valves to lift outside TS set point 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 set point.
Examination determined that sufficient corrosion bonding existed between the SRV pilot valve assembly Stellite 21 disc and the pilot valve Stellite 6 in-body seat to cause the SRV pilot valves to lift outside TS set point tolerances.
NRC FORM 366 (1-2001)