05000315/FIN-2015008-06
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Finding | |
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| Title | |
| Description | The team identified a finding of very low safety significance (Green), and an associated NCV of 10 CFR 50.63, Loss of All Alternating Current Power, for the failure to develop procedures to provide starting air to the EDGs to restore emergency alternating current power when recovering from a station blackout (SBO). Specifically, plant procedures did not ensure that there would be sufficient pressure in the EDG air receivers to start an EDG at the end of a 4-hour SBO coping period. In addition, the licensee did not have another proceduralized method of starting an EDG after a 4-hour period. The licensee entered this issue into their CAP as AR 2015-14802 and established an air receiver leak down rate administrative limit that would reasonably preserve sufficient pressure for four hours until the issue is resolved. The performance deficiency was more than minor because it was associated with the design control attribute of the Mitigating Systems cornerstone, and affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. The finding screened as of very low safety significance (Green). Specifically, a senior risk analyst performed a detailed risk evaluation and determined that the estimated change in core damage frequency was approximately 1.8E8/yr. The team determined that this finding had a cross cutting aspect in the area of problem identification and resolution because the licensee did not systematically and effectively evaluate relevant external operating experience. Specifically, the licensee self-assessment, conducted in preparation to this inspection, reviewed a similar issue identified at a different station and incorrectly concluded that, This issue is not likely to occur at Cook. |
| Site: | Cook  |
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| Report | IR 05000315/2015008 Section 1R21 |
| Date counted | Dec 31, 2015 (2015Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21M |
| Inspectors (proximate) | A Dunlop B Parks C Baron C Lipa L Smith M Jeffers N Feliz-Adorno R Walton S Kobylarz |
| Violation of: | 10 CFR 50.63 |
| INPO aspect | |
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Finding - Cook - IR 05000315/2015008 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Cook) @ 2015Q4
Self-Identified List (Cook)
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