05000346/FIN-2015008-02
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Finding | |
|---|---|
| Title | Failure to Comply with IEEE 308-1971 for the Required Independence of Safety-Related Essential Inverter Distribution Systems |
| Description | The inspectors identified a finding of very-low safety significance (Green), and an associated NCV of 10 CFR Part 50, Appendix B, Criterion III, Design Control, for the failure to demonstrate compliance with Institute of Electrical and Electronics Engineers (IEEE) 308-1971, IEEE Standard Criteria for Class 1E Electric Systems for Nuclear Power Generating Stations, for the required independence of essential safety-related inverter distribution system channels. Specifically, a common mode failure due to inadequate fault protection on several outside distribution panels could cause the loss o
redundant safety-related inverters. The licensee entered this finding into their CAP, and initiated a Standing Order that would identify the affected circuit breakers and require they be opened based on a tornado warning that could potentially affect the site. The finding was determined to be more than minor because it was associated with the Mitigating System cornerstone attribute of Protection Against External Factors, 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) based on a SDP Phase II analysis that determined a conservative delta core damage frequency (?CDF) of 1.29E-7/yr. The inspectors did not identify a cross-cutting aspect associated with this finding because the finding was not representative of current performance. |
| Site: | Davis Besse  |
|---|---|
| Report | IR 05000346/2015008 Section 1R21 |
| Date counted | Mar 31, 2015 (2015Q1) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | A Dunlop C Baron C Lipa G O'Dwyer N Valos S Kobylarz S Sheldon |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
| INPO aspect | |
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Finding - Davis Besse - IR 05000346/2015008 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Davis Besse) @ 2015Q1
Self-Identified List (Davis Besse)
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