Finding | |
|---|---|
| Title | Over-Duty Breakers on Safety-Related Buses on Unit 2 |
| Description | The team identified a finding of very low safety significance (Green) and an associated non-cited violation (NCV) of Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix B, Criterion III, Design Control. Specifically, Dominion incorrectly concluded that the 480V safety-related breakers were conforming to the plants licensing basis following their identification that the calculated short circuit fault current exceeded the breaker rating. Dominions evaluation failed to take into consideration that non-class 1E loads fed from safety-related buses must be isolated from the class 1E system by fully qualified safety-related isolation devices (breakers). Dominions design basis requires that a circuit fault on the non-class 1E side of the isolation device shall not cause the loss of the associated safety-related system |
| Site: | Millstone  |
|---|---|
| Report | IR 05000336/2018010 Section 1R21 |
| Date counted | Jun 30, 2018 (2018Q2) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21M |
| Inspectors (proximate) | K Mangan M Patel J Brand J Rady C Lally C Baron J Nicely M Gray |
| Violation of: | 10 CFR 50 Appendix B 10 CFR 50 Appendix B Criterion III, Design Control |
| CCA | P.2, Evaluation |
| INPO aspect | PI.2 |
| ' | |
Finding - Millstone - IR 05000336/2018010 | |||||||||||||||||||||||||||||||||||||||||
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Finding List (Millstone) @ 2018Q2
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