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Entered date | Event description | |
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ENS 40298 | 5 November 2003 03:45:00 | Unit 2 auxiliary feedwater support systems actuated during scheduled ATWS testing when an unrelated clearance order placement de-energized two 6.9 kv busses (256 and 258). The 2 of 4 6.9 kv bus undervoltage coincidence initiated a valid auto-start signal causing lube oil pumps 2AF01PA-A, 2AF01PB-A and 2AF01PB-C to start. Auxiliary Feedwater Pump AOV discharge valves 2AF004A and 2AF004B auto opened. 2AF01PA 4kv breaker, which was in the equipment test position. Neither auxiliary feedwater pump started and no water transferred to the steam generators. The licensee notified the NRC resident inspector. |
ENS 45104 | 29 May 2009 04:49:00 | At 2140 on 5/28/09 Braidwood Station identified a loss of control power for a Safety Related MCC (Motor Control Center) which provided power to SVAG (Single Valve Actuation Group) valves associated with both trains of the ECCS system. The MCC is normally de-energized to maintain the valve power removed in accordance with Tech Specs for ECCS. Loss of the control power for the associated MCC would prevent operation of these valves, which would prevent realignment of components required for transfer to cold leg recirculation and hot leg recirculation for long term core cooling. Entry was made into LCO 3.5.2, ECCS Operating, and LCO 3.0.3 due to inoperability of both trains of ECCS based on the inability to realign portions of both trains of the ECCS system from injection to cold leg recirculation and subsequent hot leg recirculation. At 2230 on 5/28/09 preparations had been completed for ramp off line per LCO 3.0.3. Troubleshooting was performed and a blown control power fuse was identified and replaced at 2319 on 5/28/09. No Unit ramp was initiated. The NRC Resident Inspector was notified.
The purpose of this report is to retract the ENS report made on May 29, 2009 at 04:49 EDT (ENS #45104) under 10CFR50.72(b)(3)(v)(B), a condition that could have prevented fulfillment of a safety function. The initial report was made based on identification of a loss of control power for a Safety Related MCC (Motor Control Center), which provided power to SVAG (Single Valve Actuation Group) valves associated with both trains of the ECCS system. The MCC is normally de-energized to maintain the valve power removed in accordance with Technical Specifications. The loss of the control power for the associated MCC would prevent operation of these valves. It was initially concluded that this condition would prevent realignment of components required for transfer to cold leg recirculation and hot leg recirculation for long term core cooling. Therefore, the referenced ENS report was made for a loss of safety function. Subsequent review of UFSAR information and previously developed analytical data determined that the safety function for ECCS was not lost due to the event. The failure of the MCC to energize would have NOT affected the ability of the 1B ECCS train to perform its design function of cold and hot leg recirculation. A blown control power fuse, the cause of the event, was identified and replaced on May 28, 2009 at 23:19 hours. The NRC Senior Resident Inspector has been notified of this retraction. R3DO(Pelke) notified. |