05000482/FIN-2016008-02
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Finding | |
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| Title | Failure to Promptly Identify and Correct a Condition Adverse to Quality Associated with the Emergency Diesel Generator B Excitation System Diodes |
| Description | The inspectors identified a Green non-cited violation of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, for the licensees failure to assure that conditions adverse to quality, such as failures, malfunctions, and deficiencies are promptly identified and corrected. Specifically, the licensee failed to promptly identify and correct a failed rectifier bridge diode after smoke was observed coming from the three power potential transformers in the emergency diesel generator exciter cabinet NE106 on June 11, 2014, which contributed to the emergency diesel generator B being declared inoperable and unavailable when it tripped during a 24-hour surveillance test on October 6, 2014. To address the failure to take adequate corrective actions Wolf Creek entered this issue into its corrective action program as Condition Report 105480 and plans to implement a modification to install overcurrent detection for each emergency diesel generators power potential transformer. This finding is more than minor because it is associated with the equipment performance 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. Specifically, the failure to identify and correct the failed emergency diesel generator excitation system diode contributed to the emergency diesel generator B failure on October 6, 2014. The inspectors evaluated the finding using Attachment 0609.04, "Initial Characterization of Findings," worksheet to Inspection Manual Chapter (IMC) 0609, Significance Determination Process, issued June 19, 2012. The attachment instructs the inspectors to utilize IMC 0609, Appendix A, Significance Determination Process (SDP) for Findings At-Power, issued June 19, 2012. The inspectors determined this finding is not a deficiency affecting the design or qualification of a mitigating structure, system, or component that maintained its operability or functionality, the finding does not represent a loss of system and/or function, the finding does not represent an actual loss of function of at least a single train for greater than its Technical Specification allowed outage time, and the finding does not represent an actual loss of function of one or more non-Technical Specification trains of equipment designated as high safety-significant. Therefore, the inspectors determined the finding was of very low safety significance (Green). The inspectors determined that in accordance with Inspection Manual Chapter 0310, Aspects Within The Cross-Cutting Areas, issued December 4, 2014, the finding has a cross-cutting aspect in the area of human performance, conservative bias, because when smoke was identified coming from the power potential transformers on multiple occasions, licensee personnel did not use decision making-practices that emphasize prudent choices over those that are simply allowable, and a proposed action is determined to be safe in order to proceed, rather than unsafe in order to stop. As a result, the licensee missed an opportunity to identify and correct the condition of the failed diode in the static exciter [H.14]. |
| Site: | Wolf Creek  |
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| Report | IR 05000482/2016008 Section 4OA3 |
| Date counted | Jun 30, 2016 (2016Q2) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | D Dodson D Loveless F Thomas G Pick T Pruett |
| Violation of: | 10 CFR 50 Appendix B 10 CFR 50 Appendix B Criterion XVI |
| CCA | H.14, Conservative Bias |
| INPO aspect | DM.2 |
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Finding - Wolf Creek - IR 05000482/2016008 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Wolf Creek) @ 2016Q2
Self-Identified List (Wolf Creek)
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