ENS 41531
ENS Event | |
|---|---|
01:30 Mar 28, 2005 | |
| Title | Electrical Safety Bus Trip During Quad Cities Unit 1 Refueling Outage |
| Event Description | The following information was obtained from the licensee via facsimile (licensee text in quotes):
At 1930, Unit 1 experienced a loss of 480 VAC busses 18 and 19. This caused a loss of power to the Control Room Emergency Ventilation System (CREVS) and the CREVS Air Conditioning System (CREVS AC). This event also caused a loss of power to the U1 equipment that was supporting the Alternate Decay Heat Removal (ADHR) mode of operation. Power was restored to Bus 19 at 2001 and Bus 18 at 2013. The restoration of Bus 18 also restored power to CREVS and CREVS AC. All systems supporting ADHR were restored by 2015. At the time of the occurrence, the estimated time to boil without decay heat removal capability was 571 minutes. All isolations and actuations occurred as expected. The cause of the bus trips is being investigated. This Event is being reported under 50.72 (b)(3)(v)(B) and 50.72 (b)(3)(v)(D). The licensee stated at the time of the event, Busses 18 and 19 were cross-tied and the feeder breaker to Bus 18 tripped open. The breaker was changed out and power to Busses 18 and 19 restored. The cause of the Bus 18 feeder breaker trip has not yet been determined. The licensee has notified the NRC Resident Inspector.
|
| Where | |
|---|---|
Quad Cities  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-0.3 h-0.0125 days <br />-0.00179 weeks <br />-4.1094e-4 months <br />) | |
| Opened: | Tom Oseland 01:12 Mar 28, 2005 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Mar 28, 2005 |
| 41531 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (85 %) |
| After | Power Operation (85 %) |