05000352/FIN-2011003-03
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Finding | |
|---|---|
| Title | Failure to ldentify Adverse Trend regarding Out-of-Calibration lnstrumentation |
| Description | A Green self-revealing finding was identified for Exelon\'s failure to identify and correct an adverse trend regarding out-of-calibration temperature switches in the Unit 1 and Unit 2 station cooling water (SCW) systems. Specifically, between 1990 and 201 1 the SCW outlet temperature switches were checked by Exelon on a two year frequency and found to be out-of-calibration approximately 50 percent of the time. Since 2005, the switches were found out-of-calibration nearly 70 percent of the time, often by a significant amount. Each time the switches were found out-of-calibration, they were recalibrated within acceptable limits, but the adverse trend was not recognized. The inspectors determined that Exelon\'s failure to identify and correct the adverse trend of out of calibration SCW outlet temperature switches was a performance deficiency which was reasonably within the licensee\'s ability to foresee and prevent. Specifically, Exelon\'s Performance Monitoring Program, described in ER-AA-2003, should have identified the trend during the system engineer\'s annual review of cause and repair codes for completed work orders. Exelon entered the issue into the CAP for resolution. The finding was more than minor because it was associated with the equipment performance attribute of the Initiating Events cornerstone and affected the cornerstone objective of limiting the likelihood of events that upset plant stability. Specifically, on February 25,2011, the\'out of calibration SCW outlet temperature switches resulted in a SCW runback and manual scram of Limerick Unit 2 when the outlet temperature switches actuated 15 degrees lower than their intended set point. The finding was determined to be of very low safety significance (Green) in accordance with Phase 1 of IMC 0609, significance Determination Process, because the finding did not contribute to both the likelihood of a reactor trip and the likelihood that mitigation equipment or functions would not be available. The inspectors determined that this finding had a cross-cutting aspect in the area of Problem ldentification and Resolution, Corrective Action Program, because Exelon did not identify the trend of out-of-calibration temperature switches in a timely manner. Exelon relied on the implementation of a thorough Performance Monitoring Program to supplement their CAP in the specific area of instrument performance monitoring and trending, and this program failed to detect the adverse trend in instrument performance. |
| Site: | Limerick  |
|---|---|
| Report | IR 05000352/2011003 Section 4OA2 |
| Date counted | Jun 30, 2011 (2011Q2) |
| Type: | Finding: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | E Dipaolo T Moslak S Barr N Sieller P Krohn E Burket |
| CCA | P.4, Trending |
| INPO aspect | PI.4 |
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Finding - Limerick - IR 05000352/2011003 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Limerick) @ 2011Q2
Self-Identified List (Limerick)
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