05000382/FIN-2010005-04
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Finding | |
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Title | Failure to Conduct Timely Corrective Actions to Replace Degraded Diodes in Safety Related Inverters |
Description | A self-revealing non-cited violation of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, occurred because the licensee did not promptly correct a significant condition adverse to quality that affected static uninterruptible power supply inverters used to power vital and safety related loads. Specifically, the licensee did not conduct timely corrective actions following identification of degraded diodes in static uninterruptible power supply A and B inverters, respectively. As a result, this led to another failure of a static uninterruptible power supply inverter. The licensee entered this issue into their corrective action program for resolution as CR-WF3-2011-0217. The immediate corrective actions following the additional failure included installation of newly tested diodes from a different batch, new fuses and a new silicon controlled rectifier. The planned corrective actions included implementation of an increased condition based testing preventive maintenance frequency and a maintenance activity to perform preinstallation testing on all new diodes and rectifiers. This finding is greater than minor because it is associated with the equipment performance attribute of the Mitigating System cornerstone and affects the cornerstone objective to ensure the availability and reliability of static uninterruptible power supply inverters that respond to initiating events to prevent undesirable consequences in that these inverters supply power to vital and safety related loads. The inspectors evaluated the significance of this finding using Phase 1 of the IMC 0609, Appendix A, Significance Determination of Reactor Inspection Findings for At-Power Situations given the importance of the system and the fact that this condition affects static uninterruptible power supplies A and B. The inspectors determined that the finding was of very low safety significance (Green) because it is not a design or qualification deficiency, did not represent a loss of a safety function of a system or a single train greater than its Technical Specification completion time, and did not screen as potentially risk significant due to external events. This finding has a crosscutting aspect in the decision-making component of human performance because the licensee did not make safety-significant or risk-significant decisions using a systematic process, especially when faced with uncertain or unexpected plant conditions, to ensure safety is maintained. |
Site: | Waterford ![]() |
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Report | IR 05000382/2010005 Section 4OA2 |
Date counted | Dec 31, 2010 (2010Q4) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | Self-revealing |
Inspection Procedure: | IP 71152 |
Inspectors (proximate) | L Ricketson P Elkmann M Davis D Jones T Burns J Clark D Overland R Latta C Steely N Greene P Prescott |
CCA | H.13, Consistent Process |
INPO aspect | DM.1 |
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Finding - Waterford - IR 05000382/2010005 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Waterford) @ 2010Q4
Self-Identified List (Waterford)
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