05000334/FIN-2011007-04
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Finding | |
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| Title | Offsite Power Non-Conservative Post Transient Voltage Calculations |
| Description | The team identified a finding of very low safety significance involving a non-cited violation of 10 CFR 50, Appendix B, Criterion lll, Design Control, because FENOC did not perform adequate voltage calculations to verify that vital bus voltage levels would be adequate when offsite power was the bus voltage source. The team determined that nonconservative assumptions and evaluations caused the calculation results to predict higher bus voltage levels than could actually occur. Specifically, the team found that FENOC\'s calculational assumptions related to the initial tap position of the SSSTs following bus transfers, evaluation of the effect of the voltage dips that occur during a fast bus transfer, and assumptions for the post event grid voltage condition following the main generator trip could be worse than assumed in the calculation. FENOC entered the issue into the corrective action program, and revised calculations and evaluated post event grid voltage conditions to verify the adequacy of the offsite power source. The team determined that this issue was more than minor because it was associated with the Mitigating Systems Cornerstone attribute of Design Control, and adversely affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. The finding was of very low safety significance (Green) because it was a design deficiency confirmed not to result in a loss of operability or functionality. The team determined that there was not a crosscutting aspect associated with this finding because it was not indicative of current performance. |
| Site: | Beaver Valley |
|---|---|
| Report | IR 05000334/2011007 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) | K Mangan G Skinner F Arner M Young J Ayala M Yeminy L Doerflein |
| INPO aspect | |
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Finding - Beaver Valley - IR 05000334/2011007 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Beaver Valley) @ 2011Q2
Self-Identified List (Beaver Valley)
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