05000482/FIN-2010003-03
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Finding | |
|---|---|
| Title | Nonsafety Power Supply Causes Failure of Emergency Diesel Generator A |
| Description | The inspectors identified a Green noncited violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control, for the failure of the licensee to ensure the design of the emergency diesel local annunciator power supply circuit such that its failure would not cause failure of the associated emergency diesel generator. On October 22, 2009, Wolf Creek was defueled when the control room received annunciators for emergency diesel generator A. The power supply for the local annunciators had input enough noise or voltage spikes on to the safety-related power wires to cause the speed switch to actuate while the engine was in standby. This inhibited engine start. The power supply was replaced and emergency diesel generator A was returned to service on October 23, 2009. Condition Report 21039 examined this failure but failed to identify that the vendors circuit analysis did not consider voltage ripple as a failure mode and that the requirements of IEEE 384-1974 were not met. The nonsafety-related power supply was not supposed to be able to cause the failure of the safety-related emergency diesel generator. The licensee placed this issue into the corrective action program as Condition Reports 25663, 24867, and 25479. The inspectors determined the failure to ensure that the licensing basis for the emergency diesel generators was being met to be the performance deficiency. This finding was more than minor because it was associated with the Mitigating Systems Cornerstone attribute of human performance and it affected the objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences (i.e., core damage). Using Inspection Manual Chapter 0609.04, Phase 1 - Initial Screening and Characterization of Findings, the finding was determined to have very low safety significance because emergency diesel generator A was out of service for less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. This finding has a crosscutting aspect in the area of problem identification and resolution associated with the corrective action program because the licensee failed to evaluate this failure mode against the vendors circuit analysis |
| Site: | Wolf Creek  |
|---|---|
| Report | IR 05000482/2010003 Section 4OA2 |
| Date counted | Jun 30, 2010 (2010Q2) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | R Deese G Guerra C Graves G Miller C Long C Peabody G Apger N Greene |
| CCA | P.2, Evaluation |
| INPO aspect | PI.2 |
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Finding - Wolf Creek - IR 05000482/2010003 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Wolf Creek) @ 2010Q2
Self-Identified List (Wolf Creek)
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