05000271/FIN-2013005-02
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Finding | |
|---|---|
| Title | Inadequate Risk Assessment for Isolating All Nitrogen Supply to the Containment Instrument Air System |
| Description | The inspectors identified a NCV of 10 CFR 50.65, Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants, paragraph (a)(4), for Entergys failure to conduct an adequate risk assessment prior to isolating the nitrogen supply to the containment instrument air system. Specifically, the inspectors identified that Entergy personnel had not correctly analyzed the impact to plant risk with the liquid nitrogen supply, containment air compressor, and safety relief valve (SRV) nitrogen bottle backup supply removed from service. Entergys corrective actions included establishing a contingency to restore nitrogen supply, protecting further equipment, initiating a condition report, and revising the procedures for drywell entry to maintain the SRV nitrogen backup bottle supply in service until the reactor is shutdown. This finding is more than minor because it is associated with the configuration control attribute of the Mitigating Systems cornerstone and affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. The inspectors reviewed IMC 0612, Appendix E, Examples of Minor Issues, and found that example 7.e was similar to the issue. Specifically, the inspectors determined that the issue was more than minor because the overall elevated plant risk put the plant into a higher risk category established by Entergy. The inspectors determined the significance of the finding using IMC 0609, Appendix K, Maintenance Risk Assessment and Risk Management Significance Determination Process. The finding was determined to be of very low safety significance (Green) because the Incremental Core Damage Probability Deficit for the timeframe that the nitrogen supply system was unavailable was less than 1E-6 (approximately 1E-7). The inspectors determined that the finding had a cross-cutting aspect in Human Performance, Decision- Making component, because Entergy failed to use a systematic process using available risk assessment guidance and did not obtain interdisciplinary input to make a risk-significant decision H.1(a). |
| Site: | Vermont Yankee  |
|---|---|
| Report | IR 05000271/2013005 Section 1R13 |
| Date counted | Dec 31, 2013 (2013Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.13 |
| Inspectors (proximate) | C Lally J Furia J Laughlin J Schoppy R Mckinley S Rich S Rutenkroger |
| Violation of: | 10 CFR 50.65 |
| CCA | H.13, Consistent Process |
| INPO aspect | DM.1 |
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Finding - Vermont Yankee - IR 05000271/2013005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Vermont Yankee) @ 2013Q4
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