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| Entered date | Event description | |
|---|---|---|
| ENS 45558 | 10 December 2009 12:48:00 | On December 9, 2009, at 1423 hours, Unit 2 tripped offline due to the loss of 'C' Reserve Station Service Transformer. This resulted in a loss of power to one of the bearing cooling system level control valves (LCV). The affected LCV failed open, which caused the bearing cooling tower basin to overflow and release bearing cooling water to Lake Anna. By approximately 1530 hours, plant personnel had manually isolated the bearing cooling water system and the flow to the lake stopped shortly afterwards. Based on the duration of the event (approximately 70 minutes) and the maximum discharge flow rate of a bearing cooling water make-up pump (850 gpm), no more than 59,500 gal. of water were discharged to the lake. Based on visual observation of the actual flow going to the lake, it was estimated that approximately 35,000 gal. were discharged. The bearing cooling water was sampled on 12/09/09 by the Chemistry Department as part of their routine chemistry surveillance. All chemical parameters analyzed were within VPDES (Virginia Pollutant Discharge Elimination System) permit limits. There was no violation of permit parameters from this discharge and no adverse impact to the environment was observed. Bearing cooling system chemistry is maintained to meet VPDES discharge limits. At 1035 hours on December 10, 2009, a 24-hour notification of the unusual discharge was made to the Virginia Department of Environmental Quality in accordance with the North Anna VPDES permit. This issue is being reported per 10CFR50.72(b)(2)(xi) as an event where notification of other government agencies has been made. The NRC resident inspector has been notified. |