05000261/FIN-2011004-01
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Finding | |
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| Title | Water Intrusion into Safety-Related Buildings due to Inadequate Design of Site Storm Water Runoff Drainage System |
| Description | A self-revealing apparent violation (AV) of 10 CFR 50, Appendix B, Criterion III, Design Control, was identified for the licenseei12s failure to consider how the aggregate changes to the sitei12s topography could impact the sitei12s ability to drain storm water runoff and adequately respond to localized flooding during periods of heavy rain. This resulted in the ponding of storm water runoff, the subsequent direction of runoff flow towards the power block, overfilling of the retention basin, backup of the storm drainage system, and ultimately, uncontrolled water intrusion into safety-related equipment rooms in the auxiliary building. The licensee took immediate actions to remove the water from the affected plant buildings and grounds. In addition, within a few weeks of the event, the licensee repaired the washed out area of the berm just to the north of the power block, and performed interim adjustments to site topography to limit ponding near the berm. The licensee plans to perform additional site grade and trench restoration and remediation to permanently prevent site ponding. This issue was entered into the licensee\\\'s corrective action program as NCR 468235. The licensee\\\'s failure to consider how the aggregate changes to the site\\\'s topography could impact the site\\\'s ability to drain storm water runoff and adequately respond to localized flooding during periods of heavy rain as required by procedure EGR-NGGC- 0005, Engineering Change, was a performance deficiency. This performance deficiency was considered more than minor because it was associated with the Initiating Events Cornerstone attributes of the Design Control (plant modifications) and Protection Against External Factors (flood hazard), and adversely affected the cornerstone objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, the failure to consider aggregate changes to the site\\\'s topography on the site\\\'s ability to drain storm water runoff resulted in uncontrolled water intrusion into safety-related equipment rooms. The inspectors assessed the finding using Inspection Manual Chapter (IMC) 0609, Significance Determination Process (SDP), Att. 4, Phase 1 - Initial Screening and Characterization of Findings, and determined the finding was potentially greater than very low safety significance because the finding increases the likelihood of an external flooding event. As a result, the characterization worksheet for Initiating Events required a Phase 3 analysis using the Individual Plant Examination for External Event Submittal (IPEEE) or other existing plant specific analyses as inputs. The significance of this finding is designated as To Be Determined (TBD) until the safety characterization has been completed by the NRC Senior Reactor Analyst (SRA). The inspectors determined that the cause of this finding was related to the trending and assessment aspect in the Corrective Action Program component of the Problem Identification and Resolution cross-cutting area. |
| Site: | Robinson  |
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| Report | IR 05000261/2011004 Section 1R01 |
| Date counted | Sep 30, 2011 (2011Q3) |
| Type: | NCV: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.01 |
| Inspectors (proximate) | C Scott C Stancil E Coffman J Austin J Hickey M Coursey R Musser T Chandlerc Scottp Lessard R Musser T Chandler |
| CCA | P.4, Trending |
| INPO aspect | PI.4 |
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Finding - Robinson - IR 05000261/2011004 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Robinson) @ 2011Q3
Self-Identified List (Robinson)
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