05000395/FIN-2011006-09
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Finding | |
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| Title | Failure to Adequately Account for the In-rush Current of the 7.2 kV Breaker Spring Charging Motors in a Safety-related Battery Voltage Drop Calculation |
| Description | The team identified a non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion III, Design Control for the licensees failure to adequately account for the in-rush current of the 7.2 kV breaker spring charging motors in a safety-related calculation. Specifically, the licensee used the steady-state current instead of the more limiting in-rush current in battery voltage drop calculation. The licensee entered the issue into their corrective action program as CR 11-00989 and performed testing to confirm the ability of the breaker to close with reduced voltage. The failure of the licensee to use the more limiting in-rush current in the safetyrelated calculation is a performance deficiency. The performance deficiency was more than minor because it adversely affected the mitigating systems cornerstone attribute of design control and adversely affected the cornerstone objective to ensure the availability, reliability and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the deficiencies in Calculation DC08320-010 resulted in a reasonable doubt that the B service water pump breaker would not have reliably closed during a design bases event. The performance deficiency resulted in the breakers not being tested with the lower voltage (71.04vdc) that would be available during an event. In accordance with NRC IMC 0609.04, Initial Screening and Characterization of Findings , the inspectors conducted a Phase 1 Significance Determination Process (SDP) screening and determined the finding to be of very low safety significance (Green) because it was a design deficiency confirmed not to result in the loss of operability or functionality, did not represent the loss of a system safety function and did not screen as potentially risk significant due to a seismic, flooding, or severe weather initiating event. A cross-cutting aspect was not identified because the finding does not represent current performance. |
| Site: | Summer  |
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| Report | IR 05000395/2011006 Section 1R21 |
| Date counted | Jun 30, 2011 (2011Q2) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | D Jones D Mas-Penaranda M Yeminy S Sandal B Desai J Eargle |
| INPO aspect | |
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Finding - Summer - IR 05000395/2011006 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Summer) @ 2011Q2
Self-Identified List (Summer)
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