05000458/FIN-2010003-01
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Finding | |
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| Title | Inadequate Risk Assessment for High Pressure Core Spray Pump Room Unit Cooler Maintenance |
| Description | The inspectors identified a noncited violation of 10 CFR 50.65(a)(4) involving the licensees failure to perform an adequate risk assessment while the high pressure core spray room unit cooler was unavailable. Specifically, the licensee assumed that risk would remain green and high pressure core spray would continue to inject into the reactor vessel for 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after room cooling was made unavailable, when, in fact, risk became yellow because high pressure core spray would become unreliable after approximately 60 minutes due to instrument failure in the pumps minimum flow logic. As immediate corrective action, the licensee issued a standing order that administratively considered high pressure core spray unavailable when its room cooler is removed from service. The licensee entered this issue into their corrective action program as Condition Report CR-RBS-2010-02937
This issue was more than minor because it was associated with the equipment performance attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Using Inspection Manual Chapter 0609, Significance Determination Process, Appendix K, Maintenance Risk Assessment and Risk Management Significance Determination Process, the finding is determined to have very low safety significance (Green) because the incremental core damage probability deficit for the affected time period is less than 1.0E-6 and because the licensee used incorrect risk assumptions that changed the outcome of their risk assessment. There is no crosscutting aspect associated with this violation because the assumptions that lead to the performance deficiency are not indicative of current licensee performance. |
| Site: | River Bend  |
|---|---|
| Report | IR 05000458/2010003 Section 1R13 |
| Date counted | Jun 30, 2010 (2010Q2) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.13 |
| Inspectors (proximate) | P Elkmann L Carson G Larkin V Gaddy A Fairbanks C Norton N Greene |
| INPO aspect | |
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Finding - River Bend - IR 05000458/2010003 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (River Bend) @ 2010Q2
Self-Identified List (River Bend)
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