05000352/FIN-2012010-01
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Finding | |
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| Title | Failure to Take Timely Corrective Actions to Address the 144D Load Center ODM Contingency Actions |
| Description | The inspectors identified a finding of very low safety significance (Green) for Exelons failure to complete an evaluation of the off-normal bus alignment prior to the summer period. Consequently, on July 18, 2012, LGS experienced a fault of the 124A load center (LC) transformer which led to an unplanned manual scram. Exelons root cause evaluation for this event identified that a contributing cause was the electrical configuration being in an off-normal bus alignment (114A LC cross-tied to the 124A LC) for an extended period due to the failure of the 144D transformer, which placed more load on the degraded 124A connection and contributed to its failure. Exelon has entered the issue into the corrective action program (AR 1437657). This finding was more than minor because it is similar to examples 4.f and 4.g of IMC 0612, Appendix E, Examples of Minor Issues, in that operators inserted a manual scram per procedural requirements following the loss of the reactor recirculation pumps (RRP) associated with the 124A LC transformer failure. Additionally, the finding was more than minor because it is associated with the equipment performance attribute of the Initiating Events cornerstone and 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. This finding was of very low safety significance (Green) because the finding did cause a reactor trip but did not cause a loss of mitigation equipment relied upon to transition the plant from the onset of the trip to a stable shutdown condition. This finding had a cross-cutting aspect in the Problem Identification and Resolution cross-cutting area, Corrective Action Program component, because Exelon did not take appropriate corrective actions to address safety issues and adverse trends in a timely manner, commensurate with their safety significance and complexity P.1(d). Specifically, Exelons failure to restore the normal 124A LC alignment or evaluate the effects of continuing the off-normal alignment during the summer period in a timely manner placed additional loading on the transformer contributing to the failure. |
| Site: | Limerick  |
|---|---|
| Report | IR 05000352/2012010 Section 4OA2 |
| Date counted | Dec 31, 2012 (2012Q4) |
| Type: | Finding: Green |
| cornerstone | Initiating Events |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | A Defrancisco P Krohn J Hawkins A Dugandzic |
| CCA | P.3, Resolution |
| INPO aspect | PI.3 |
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Finding - Limerick - IR 05000352/2012010 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Limerick) @ 2012Q4
Self-Identified List (Limerick)
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