05000352/FIN-2015004-01
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Finding | |
|---|---|
| Title | Seismic Qualification of Safety Related Block Wall Not Maintained |
| Description | The inspectors identified a Green non-cited violation (NCV) of 10 CFR 50, Appendix B, Criterion III, Design Control, because Exelon did not properly store circuit breakers and ground trucks in accordance with the established design in order to maintain the seismic qualification of safety-related structures. Specifically, Exelon personnel attached stored circuit breakers and ground trucks to safety-related concrete block walls but did not evaluate the greater weight of circuit breakers, did not maintain the required separation distances, and did not attach all equipment to required attachment points. Exelon initiated issue report (IR) 2592543, removed all stored circuit breakers from the location, rearranged ground trucks to attach them only to designated wall anchors that maintained the required separation distance, and required refresher training of all operators and electrical maintenance personnel on proper spacing and restraint of circuit breakers and ground trucks. This finding is more than minor because it adversely affected the protection against external factors (seismic) attribute of the mitigating systems cornerstone to ensure the availability and reliability of systems that respond to initiating events to prevent undesirable consequences (i.e. core damage). Specifically, the improper storage of the circuit breakers and ground trucks affected the seismic qualification of the concrete block walls separating the switchgear of the emergency diesel generators (EDG) which had potential to damage the block walls during a seismic event. Using IMC 0609, Appendix A, Exhibit 4, the inspectors determined that this finding was of very low safety significance (Green). Specifically, the inspectors determined that the performance deficiency only affected the seismic qualification of the concrete block wall, the loss of the concrete wall by itself would not necessarily cause an initiating event or degradation of the EDG system, and the finding did not involve the total loss of any safety function. Furthermore, the inspectors consulted a Senior Risk Analyst regarding the risk screening and determined that a failure of the walls would not necessarily result in the degradation or failure of the EDG systems. Specifically, for screening purposes, assuming total failure of the concrete masonry walls only introduces a potential of degraded performance since the switchgear are anchored to the concrete floor. As such, Exhibit 4 provides a reasonable basis for screening the finding as Green. The inspectors determined that this finding has a cross-cutting aspect in the area of Human Performance, Procedure Adherence, because equipment operators did not follow the established work instructions (posted signs). |
| Site: | Limerick  |
|---|---|
| Report | IR 05000352/2015004 Section 1R15 |
| Date counted | Dec 31, 2015 (2015Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.15 |
| Inspectors (proximate) | B Fuller D Schroeder M Fannon M Orr M Patel S Rutenkroger |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
| CCA | H.8, Procedure Adherence |
| INPO aspect | WP.4 |
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Finding - Limerick - IR 05000352/2015004 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Limerick) @ 2015Q4
Self-Identified List (Limerick)
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