05000219/FIN-2009009-01
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Finding | |
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| Title | Review Exelon\'s Root Cause Analysis for the Q121 Circuit Breaker Failure to Open on July 12, 2009 |
| Description | No findings of significance were identified. The team determined that if the Q121 circuit breaker had opened on the primary protection signal the reactor scram with a LOOP would have been avoided. The team identified an Unresolved Item pending review of Exelons root cause analysis of the failure of the Q121 circuit breaker to open and Maintenance Rule performance monitoring of this breaker. At the end of the inspection period, the Q121 breaker remained open and the root cause for the breaker failing to open had not been completed. The OC maintenance rule program included the capability of the offsite power system to conduct 34.5 kV power to the Startup Transformers and the capability of the protective relays and controls to operate the breakers on demand to perform their protective functions. As such, the failure of the breaker to open during the July 2009 event, appeared to be a functional failure. In discussions with the transmission system operator JCP&L, following the end of the inspection, Exelon discovered that there had been a previous instance in June 2009,where the Q121 breaker had failed to open when demanded by protective relaying. Apparently in that instance the fault current was sufficiently low such that the OC generator was not impacted. At the close of the inspection period Exelon had not completed the root cause analysis for the failure and was reviewing the impact of the newly identified failure in June 2009 and the July 2009 failure for applicability to the OC Maintenance Rule Program.URI 05000219/2009009-01, Review Exelons Root Cause Analysis for the Q121Circuit Breaker Failure to Open on July 12, 200 |
| Site: | Oyster Creek |
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| Report | IR 05000219/2009009 Section 4OA5 |
| Date counted | Sep 30, 2009 (2009Q3) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 93812 |
| Inspectors (proximate) | M Patel W Schmidt J Kulp M Ferdas P Presby R Bellamy J Heinly R Pinney T Hediganw Schmidtj Kulp R Bellamy J Ambrosini |
| INPO aspect | |
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Finding - Oyster Creek - IR 05000219/2009009 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Oyster Creek) @ 2009Q3
Self-Identified List (Oyster Creek)
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