05000456/FIN-2014004-01
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Finding | |
|---|---|
| Title | Adverse Impact of Floor Drain Design on Flooding Analysis |
| Description | The inspectors identified a finding of very low safety significance and an associated NCV of 10 CFR Part 50, Appendix B, Criterion III Design Control, when licensee personnel failed to verify the design of bag-strainers in the floor drains of the auxiliary building and their impact on the associated flooding analysis. Specifically, when Calculation 3C80686002, Auxiliary Building Flood Level Calculation, was revised on May 16, 2013, the licensee credited the use of floor drains, which had bag-type strainers that were designed in such a way that they increased the potential for blockage, and therefore adversely impacted the analysis of record for internal flooding. This issue was entered into the licensees Corrective Action Program (CAP) as Issue Report (IR) 2385204, NRC Questions on Aux [Auxiliary] Building Flood Evaluation. Corrective actions for this issue included instituting Standing Order 14005 to prevent the interim removal of flood seals, and a plan to revise Calculation 3C80685002 to resolve the identified non-conformances. The inspectors determined that the performance deficiency was more than minor in accordance with IMC 0612, Appendix B, Issue Screening, because the issue 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 (i.e., core damage). Specifically, the floor drain strainer bags were inadequately designed in such a manner that instead of ensuring that the floor drains would be able to function properly to remove flood water, they would act to increase the possibility that the floor drains would become plugged and unable to perform this function adequately. The inspectors concluded that the finding was of very low safety significance in accordance with IMC 0609, Appendix A, Exhibit 2 and Exhibit 4. The inspectors determined that the finding had a cross-cutting aspect in the Evaluation component of the Problem Identification and Resolution (PI&R) cross-cutting area because the licensee failed to thoroughly evaluate the issue to ensure that the resolution addressed the causes. Specifically, when the licensee made a major revision to Calculation 3C80685002 in 2013 to, in part, incorporate minor revisions and address non-conservatisms in the calculation, the licensee failed to adequately consider a previous minor revision that had removed credit for 3 the drain system due to problems with its design that were previously identified by the NRC (P.2). |
| Site: | Braidwood  |
|---|---|
| Report | IR 05000456/2014004 Section 1R06 |
| Date counted | Sep 30, 2014 (2014Q3) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.06 |
| Inspectors (proximate) | B Boston D Betancourt E Duncan J Benjamin J Laughlin L Rodriguez M Learn M Perry R Edwards R Jickling T Go |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
| CCA | P.2, Evaluation |
| INPO aspect | PI.2 |
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Finding - Braidwood - IR 05000456/2014004 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Braidwood) @ 2014Q3
Self-Identified List (Braidwood)
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