05000280/FIN-2009004-05
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Finding | |
|---|---|
| Title | Failure to promptly identify and correct a ground on safety bus 1H |
| Description | A Green NCV of 10 CFR 50, Appendix B, Criterion XVI, Corrective Action, was identified by the inspectors for failure to promptly identify and correct a condition adverse to quality related to a ground on emergency safety bus 1H. This resulted in the degraded condition being allowed to exist for 72 days prior to de-energizing the containment recirculation fan and correcting the adverse condition (CR 336041). This finding is more than minor because it adversely impacted the equipment performance attribute of the reactor safety mitigating system cornerstone and its objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. The finding, evaluated per MC-0609, Appendix A, Determining the Significance of Reactor Inspection Findings for At-Power Situations, was determined to be of very low safety significance (GREEN). The finding screened to a Phase II assessment on the assumption that a second ground would result in a complete loss of the safety bus and its safety function. The Phase II analysis was performed for the core damage sequence Loss of a 4.16Kv Bus (1J or 1H) utilizing an increased initiating event likelihood (IEL) value of 1 due to the degraded condition of the 1H bus. The duration of the degraded condition was 72 days. The finding was not greater than Green because full mitigation capability of the opposite train remained available. This finding has a cross cutting aspect in human performance, decision making, in that the licensee did not use conservative assumptions in their decision making process (H.1.b) |
| Site: | Surry  |
|---|---|
| Report | IR 05000280/2009004 Section 4OA2 |
| Date counted | Sep 30, 2009 (2009Q3) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | C Welch D Arnett G Mccoy J Nadel |
| CCA | H.14, Conservative Bias |
| INPO aspect | DM.2 |
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Finding - Surry - IR 05000280/2009004 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Surry) @ 2009Q3
Self-Identified List (Surry)
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