05000247/FIN-2012007-01
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Finding | |
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| Title | Inadequate Design Verification that Bus 6A supply breaker amptector would not inadvertently trip and lockout bus during degraded grid accident Sl load current |
| Description | The team identified a finding of very low safety significance involving a non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion lll, Design Control, because Entergy had not verified the adequacy of the design with respect to ensuring the Unit 2 480V emergency Bus 64 offsite power supply breaker amptector trip system would not inadvertently trip under accident load during degraded grid conditions. Specifically, Entergy\'s evaluation did not account for the overall accuracy of the amptector long-time over-current trip system and the loop calibration procedures did not verify that the breaker would trip within the assumed trip system tolerance of t4 percent. Entergy entered the issue into their corrective action program to address the design analysis deficiency and evaluate the adequacy of the calibration procedures, and performed an operability evaluation to ensure the breaker would not inadvertently trip during anticipated accident loads. The performance deficiency was determined to be more than minor because it was associated with the design control attribute of the Mitigating Systems Cornerstone 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 team evaluated the finding in accordance with IMC 0609, Appendix A, The Significance Determination Process (SDP) for Findings at Power, Exhibit 2 - Mitigating Systems Screening Questions. The finding was determined to be of very low safety significance (Green) because it was a design deficiency confirmed not to result in loss of operability. This finding was not assigned a cross-cutting aspect because it was a historical design issue not indicative of current performance. Specifically, the deficiency originated in a 1993 design evaluation. |
| Site: | Indian Point  |
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| Report | IR 05000247/2012007 Section 1R21 |
| Date counted | Dec 31, 2012 (2012Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | M Singletary M Yeminy A Della Grecad Kern D Orr F Arner J Schoppy L Doerflein |
| INPO aspect | |
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Finding - Indian Point - IR 05000247/2012007 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Indian Point) @ 2012Q4
Self-Identified List (Indian Point)
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