05000395/FIN-2009005-03
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Finding | |
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| Title | Control of Electrical Grounding Devices Resulting in Fires in the Turbine Building Non-Safety-Related Switchgear |
| Description | At approximately 3:42 p.m. on November 22, 2009, with the unit in Mode 5 (Cold Shutdown), the new main transformer was energized for testing following replacement during the refueling outage. The transformer circuit breaker immediately tripped and a loss of all station 7.2 kV balance of plant (BOP) power occurred due to a ground fault condition. Coincident with the BOP power loss, smoke alarms were received on the fire protection panel located in the control room. Shortly thereafter, heavy smoke was identified in both of the 7.2 kV BOP switchgear rooms located in the Turbine Building. The licensee dispatched the onsite fire brigade to the affected locations and contacted the offsite fire departments for support. At 4:00 p.m., the licensee declared a Notice of Unusual Event (NOUE) condition onsite per Emergency Action Level HU2.1, Fire within the Protected Area not extinguished within 15 minutes of detection or explosion within the Protected Area. When the fire brigade responded, they found indications of fires in the 1A, 1B, and 1C 7.2 kV BOP normal incoming breaker cubicles located in the two BOP switchgear rooms. After the initial fires were extinguished, re-flash fires were observed and extinguished by the onsite fire brigade with support from the offsite fire departments. The licensee confirmed that the fire was extinguished at 4:40 p.m. and terminated the NOUE at 6:55 p.m. At the time of the event, the inspectors were onsite and immediately responded to the control room to monitor licensee emergency actions, evaluate the actual/potential impact on safety-related equipment, and notified NRC regional and headquarters management of the event and the status of plant conditions and fire brigade response actions. The inspectors verified that the licensees response to the event was appropriate and consistent with emergency and fire response procedure requirements. The inspectors verified that the NRC reporting requirements for the event were properly implemented and that the licensee entered the issues related to the event into their CAP. The licensee determined that the cause of the fire was the failure to remove ground protection devices that were left in the 1A, 1B, and 1C 7.2 kV BOP normal incoming breaker cubicles earlier in the outage. With the ground devices still installed, a direct path to ground and significant arc flash occurred in each of the three 7.2 kV BOPincoming breaker cubicles when the main transformer was energized. At the end of the inspection period, the inspectors were awaiting the completion of the licensees Corrective Action Review Board review of the root cause evaluation results to understand the potential performance deficiencies. This issue is unresolved pending review of the licensees final evaluation and corrective actions by the inspectors in order to characterize this issue. This unresolved item (URI) is identified as05000395/2009005-03, Control of Electrical Grounding Devices Resulting in Fires in the Turbine Building Non-Safety-Related Switchgear |
| Site: | Summer  |
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| Report | IR 05000395/2009005 Section 4OA3 |
| Date counted | Dec 31, 2009 (2009Q4) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | J Polickoski J Zeiler G Mccoye Michelr Hamilton L Miller J Polickoski J Zeiler G Mccoy M Coursey |
| INPO aspect | |
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Finding - Summer - IR 05000395/2009005 | |||||||||||||||||||||||||
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Finding List (Summer) @ 2009Q4
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