05000482/FIN-2012004-02
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Finding | |
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Title | Inadequate Operability Evaluation for a Degraded Switchgear Cooling Fan |
Description | On August 30, 2012, inspectors identified a non-cited violation of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, for an operability evaluation that failed to adequately evaluate the operability of safety-related electrical equipment. On July 9, 2012, the inspectors identified that train B air conditioning unit SGK05B had a flow rate of 1,028 cfm below that of its design flow rate of 11,500 cfm during a flow rate surveillance test on June 8, 2011. Wolf Creek performed an operability evaluation when the inspectors questioned the test results. The inspectors found that the evaluation contained non-conservative errors in cooling coil capacity specifications, incorrect assumptions for heat conducted into the switchgear rooms, unaccounted for latent and sensible heat sources, and a single failure that was not considered. Wolf Creek then expanded the operability evaluations to both trains, was performing cause evaluations on the repetitive operability evaluations, and planned to reconstitute the design basis for the system. This was captured in condition reports 54791, 54865, 55712, 55994, 56020, 56253, 56014, 56966, and 28252. The failure to perform an operability evaluation that accurately reflected the plant design was a performance deficiency. The performance deficiency is more than minor because it impacted the design control attribute of the Mitigating Systems Cornerstone and affected the objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences because the licensee had to re-perform the evaluations to demonstrate that adequate capability existed. Using Inspection Manual Chapter 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power, this finding was determined to be of very low safety significance because operability evaluations were ultimately able to demonstrate adequate heat removal capability for the Class IE electrical equipment rooms. The inspectors identified the cause of the finding had a crosscutting aspect in the area of problem identification and resolution because Wolf Creek did not thoroughly evaluate the - 6 - Enclosure problem such that the resolutions address causes and extent of conditions, as necessary. Specifically, the reduced flow rate was a narrow focus of the evaluation and did not consider ongoing system design problems in evaluating the losses of margin |
Site: | Wolf Creek |
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Report | IR 05000482/2012004 Section 1R15 |
Date counted | Sep 30, 2012 (2012Q3) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.15 |
Inspectors (proximate) | C Long C Peabody C Speer G Guerra J Laughlin J Watkins L Ricketson N Greene N Makris N O'Keefe R Kopriva S Hedger |
CCA | P.2, Evaluation |
INPO aspect | PI.2 |
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Finding List (Wolf Creek) @ 2012Q3
Self-Identified List (Wolf Creek)
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