05000382/FIN-2015001-01
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Finding | |
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| Title | Failure to Identify and Perform Testing of Safety-Related Dry Cooling Tower Tube Bundle Isolation Valves |
| Description | The inspectors identified a non-cited violation of 10 CFR Part 50, Appendix B, Criterion XI, Test Control, because the licensee did not identify and perform testing for safety-related components to demonstrate that they would perform satisfactorily in service. Specifically, prior to February 12, 2015, the licensee did not identify and perform testing to demonstrate that, as described in the licensees design basis, the dry cooling tower tube bundle isolation valves could be used to isolate a dry cooling tower tube bundle following a tornado missile strike on the non-missile-protected portions of the dry cooling tower. The licensee entered this condition into their corrective action program as Condition Report CR-WF3-2015-00828. The planned corrective actions are to develop seat leakage criteria for the dry cooling tower tube bundle isolation valves and to perform periodic seat leakage testing. The inspectors determined that the performance deficiency was more than minor because it was associated with the protection against external factors attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the failure to establish a test program for a safety related component to demonstrate that it would perform satisfactorily following a tornado missile strike could impact the systems ability to perform its safety function in the event of a tornado. The inspectors performed the initial significance determination using NRC Inspection Manual 0609, Appendix A, Exhibit 4, External Event Screening Questions. The finding required a detailed evaluation because it would degrade one or more trains of a system that supports a risk significant system or function. Therefore, a senior reactor analyst performed a bounding detailed risk evaluation. The analyst determined that the finding was of very low safety significance (Green). The bounding change to the core damage frequency was less than 2.9E-7/year. The finding was not significant with respect to the large early release frequency. The dominant core damage sequences included tornado-induced losses of offsite power, failure of the train B dry cooling tower pressure boundary, random failure of the train A component cooling water system, random failures of the emergency diesel generators, and failure to recover offsite power in 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. Risk was minimized because the diesel generators have air cooled radiators and do not require component cooling water to remain functional. The low tornado frequency also minimized the risk. The inspectors concluded that the finding did not have a cross-cutting aspect because the most significant contributor to the performance deficiency of not identifying the need for a leak test occurred more than two years ago and did not reflect current licensee performance. |
| Site: | Waterford  |
|---|---|
| Report | IR 05000382/2015001 Section 1R04 |
| Date counted | Mar 31, 2015 (2015Q1) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.04 |
| Inspectors (proximate) | C Speer F Ramirez G Replogle J Dixon J O'Donnell L Carson N Greene P Hernandez R Lantz |
| Violation of: | 10 CFR 50 Appendix B Criterion XI |
| INPO aspect | |
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Finding - Waterford - IR 05000382/2015001 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Waterford) @ 2015Q1
Self-Identified List (Waterford)
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