Semantic search
Jump to navigation
Jump to search
| Entered date | Event description | |
|---|---|---|
| ENS 43590 | 23 August 2007 20:14:00 | At 1530 hours on 8/23/07, Braidwood Station Unit 2 was manually tripped due to lowering condenser vacuum. The lowering condenser vacuum resulted from the trip of two circulating water pumps. The cause of the two circulating water pump tripping is under investigation. All control rods inserted and there were no complications during the trip and all systems functions as required. Following the unit trip, the Auxiliary Feedwater System actuated as expected to maintain steam generator level. At the time of the unit trip, the Braidwood Station area was experiencing severe thunderstorms. Additionally, at 1604 hours, 19 of 70 emergency sirens for the Braidwood Station were declared inoperable due to a loss of power from storms in the area. As of 1704 hours, 19 sirens (greater than 25%) remain inoperable. This event is considered a major loss of offsite response capability and applies to both Braidwood Station Unit 1 and Unit 2. These events are is being reported under: (1) 10 CFR 50.72(b)(2)(iv)(B) as an event that results in the actuation of the reactor protection system (RPS) when the reactor is critical, (2) 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the PWR auxiliary feedwater system. (3) 10 CFR 50.72(b)(3)(xiii) as a major loss of offsite response capability. All safety buses remained powered by offsite power throughout this event. Emergency diesel generators are available if needed. No steam generator PORV's lifted as a result of the trip. Decay heat is being discharged to the condenser via the steam dumps. The licensee informed the NRC Resident Inspector. |