05000461/FIN-2009005-03
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Finding | |
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| Title | Failure to Correctly Torque Valve Packing Gland Nuts Resulted in Valve Packing Failure and Unplanned Plant Shutdown |
| Description | A finding of very low safety significance with an associated Non-Cited Violation of 10 CFR 50, Appendix B, Criteria V, Instructions, Procedures, and Drawings, was self-revealed on September 29, 2009, when a steam leak developed from the reactor core isolation cooling (RCIC) system inboard steam isolation valve (1E51F0063) stem packing. This resulted in a plant shutdown due to a greater than 2 gallons-per-minute increase in unidentified reactor coolant system (RCS) leakage within the previous 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Subsequent investigation revealed that maintenance craftsmen had failed to correctly tighten the valve packing gland nuts to the as-left torque value from original packing installation when performing scheduled maintenance to verify the as-found torque value in 2006. As corrective action, the licensee replaced the 1E51F0063 valve stem packing during the subsequent forced outage and tightened the gland nuts to the correct torque value. The finding was of more than minor significance because it was associated with the Equipment Performance attribute of the Initiating Events Cornerstone and affected the cornerstone objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, the failure to correctly tighten the valve stem packing gland nuts resulted in stem packing failure and a subsequent plant shutdown due to exceeding the Technical Specification (TS) limit for an increase in unidentified RCS leakage. Although the finding resulted in exceeding the TS limit for RCS leakage, it was determined to be of very low safety significance during a Phase 2 Significance Determination Process review because there was no loss of mitigation capability for any safety system and therefore no resultant change in core damage frequency. Because the performance issue was associated with maintenance performed in February 2006, it did not necessarily reflect current licensee performance and no cross-cutting aspect was identified |
| Site: | Clinton  |
|---|---|
| Report | IR 05000461/2009005 Section 4OA2 |
| Date counted | Dec 31, 2009 (2009Q4) |
| Type: | NCV: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | D Reeser E Coffman G Roach J Bozga J Draper M Ring S Mischke B Kemker D Lords D Mcneil |
| INPO aspect | |
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Finding - Clinton - IR 05000461/2009005 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Clinton) @ 2009Q4
Self-Identified List (Clinton)
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