05000352/FIN-2013004-01
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Finding | |
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| Title | Inadequate and Untimely Corrective Actions Associated With the Unit 1 Instrument Air System |
| Description | A self-revealing finding of very low safety significance was identified for Exelons failure to take adequate and timely corrective actions to address the inadvertent depressurization of the Unit 1 Instrument Air (IA) headers. This led to a repeat depressurization of the Unit 1 IA headers when the service air compressor tripped on July 7, 2013, causing the operators to enter ON-119, Loss of Instrument Air, and reduce reactor power by 20 percent until IA header pressure could be restored and maintained. Exelons corrective actions for this issue included replacing all of the IA dryer pre-filters, creating an activity to perform dryer performance monitoring prior to any IA maintenance outage, and recalibrating all of the IA dryer pre-filter differential pressure (D/P) switches. Exelon was also in the process of evaluating a replacement component for the IA dryer D/P switches and investigating the effectiveness of the prioritization of their maintenance backlog strategy. Exelon has entered this issue into their corrective action program (CAP) as Issue Report (IR) 1569901. Exelons corrective actions to address the inadvertent depressurization of the Unit 1 IA headers on October 9, 2012, were ineffective and untimely, representing a performance deficiency that was within their ability to foresee and correct. This performance deficiency was determined to be more than minor because it affected the Equipment Performance attribute of the Initiating Events cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, unnecessary transients on the IA header increase the likelihood of a loss of IA, an unplanned down power or a potential rapid plant shutdown due to plant instability. The finding is of very low safety significance (Green) per IMC 0609, Appendix A, Exhibit 1 - Initiating Events Screening Questions, because it did not involve the complete or partial loss of a support system that contributes to the likelihood of, or cause, an initiating event and affected mitigation equipment. The finding had a cross-cutting aspect in the area of Human Performance, Resources, because Exelon did not ensure that personnel, equipment, procedures, and other resources were adequate to assure nuclear safety. Specifically, Exelon did not adequately maintain engineering and maintenance backlogs to support safety, which led to IRs (1426043 and 1426045) to check the operation of the Unit 1 IA dryer pre-filter D/P switches not being performed in a timely manner H.2(a). Exelon did not complete work associated with these IRs and failed to utilize internal operating experience concerning the creation of a time-based preventative maintenance (PM) in order to replace the pre-filters and functionally check the D/P switches prior to conducting maintenance. |
| Site: | Limerick  |
|---|---|
| Report | IR 05000352/2013004 Section 1R04 |
| Date counted | Sep 30, 2013 (2013Q3) |
| Type: | Finding: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.04 |
| Inspectors (proximate) | E Dipaolo J Laughlin R Nimitz F Bower J Hawkins D Aird |
| INPO aspect | |
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Finding - Limerick - IR 05000352/2013004 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Limerick) @ 2013Q3
Self-Identified List (Limerick)
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