05000458/FIN-2017002-02
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Finding | |
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| Title | Single Component Failure Leads to Loss of Both Divisions of Control Building Air Conditioning |
| Description | The inspectors reviewed a self-revealing, non-cited violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control, for the licensees failure to correctly translate the design basis into plant specifications. Specifically, the licensee implemented a breaker design in the control building air conditioning system that allowed a single failure of one train of the system to render the other train inoperable, contrary to the design basis. The licensee entered this condition into their corrective action program as Condition Report CR-RBS-2017-01740. The licensee restored compliance by implementing modifications to the affected breakers designed to eliminate the single failure vulnerability.The failure to correctly translate the design basis into plant specifications was a performance deficiency. The performance deficiency was more than minor, and therefore a finding, because it was associated with the design control attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the licensees failure to implement an appropriate design in the main control room and standby switchgear room air conditioning subsystems adversely affected the availability, reliability, and capability of safety-related components that rely on those subsystems for cooling. The inspectors performed the initial significance determination using NRC Inspection Manual Chapter 0609, Appendix A, Exhibit 2, Mitigating Systems Screening Questions. The finding required a detailed risk evaluation because it involved a loss of system and/or function. A Region IV senior reactor analyst performed a detailed risk evaluation for the issue and determined the issue to be of very low safety significance (Green). No cross-cutting aspect was assigned because the finding did not reflect current performance. |
| Site: | River Bend  |
|---|---|
| Report | IR 05000458/2017002 Section 4OA3 |
| Date counted | Jun 30, 2017 (2017Q2) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | J Sowa B Parks S Graves S Hedger |
| Violation of: | 10 CFR 50 Appendix B 10 CFR 50 Appendix B Criterion III, Design Control |
| INPO aspect | |
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Finding - River Bend - IR 05000458/2017002 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (River Bend) @ 2017Q2
Self-Identified List (River Bend)
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