ENS 42576
ENS Event | |
|---|---|
14:59 May 15, 2006 | |
| Title | Momentary Loss of Dhr Due to Automatic Actuation of the Keowee Emergency Power Supply |
| Event Description | Event: At 10:59 hours on 5-15-06, while in Mode 6 following completion of refueling activities, Oconee Unit 3 experienced a lockout of CT-3, the transformer for the Startup power source, which was in service at the time. This resulted in a momentary loss of AC power to the unit. Keowee Hydro Station, the Oconee emergency power source received an automatic emergency start signal, started, and closed in to supply power via the Underground Emergency Power path within approximately 40 seconds.
Initial Safety Significance: Initial conditions of significant systems: Normal power via backcharge of main transformer was not available. The Fuel Transfer Canal was full and valves open connecting it to the Spent Fuel Pool. Time to core boil was 58 minutes per procedure. The Equipment Hatch was open. The initial loss of power resulted in interruption of Decay Heat Removal (DHR) Cooling, Spent Fuel Pool Cooling, and other support systems. Power was automatically restored and the affected systems returned to service promptly. Therefore there was no safety significance to this event. Reactor Coolant System heated up from approximately 80F to approximately 89.5F during this event. Corrective Action(s): As stated, Keowee started and supplied power automatically. The appropriate Abnormal Procedures were entered to restore power and restart these systems. DHR was restored at 11:13. Actions were initiated to achieve Containment Closure due to the loss of DHR. The Equipment Hatch was closed by 11:40. Backup power is available from Central Switchyard via CT-5. The cause of the initiating transformer lock out is under investigation. The licensee informed the NRC Resident Inspector. |
| Where | |
|---|---|
Oconee  South Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-1.18 h-0.0492 days <br />-0.00702 weeks <br />-0.00162 months <br />) | |
| Opened: | Randy Todd 13:48 May 15, 2006 |
| NRC Officer: | Steve Sandin |
| Last Updated: | May 15, 2006 |
| 42576 - NRC Website | |
WEEKMONTHYEARENS 558882022-05-07T03:10:0007 May 2022 03:10:00
[Table view]10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Actuation of Emergency Feedwater ENS 557502022-02-22T03:07:00022 February 2022 03:07:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip ENS 558002022-02-13T21:25:00013 February 2022 21:25:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Feedwater System Actuation ENS 556122021-11-27T10:19:00027 November 2021 10:19:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Actuation of the Emergency AC Electrical Power System ENS 536772018-10-19T04:00:00019 October 2018 04:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Steam Seal Header Pressure Malfunction ENS 512682015-07-27T13:56:00027 July 2015 13:56:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Actuation of Unit 2 Emergency Feedwater System During Startup ENS 461592010-08-07T18:51:0007 August 2010 18:51:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip After Reactor Coolant Pumps High Vibration ENS 446382008-11-07T13:34:0007 November 2008 13:34:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip ENS 441092008-03-31T17:52:00031 March 2008 17:52:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip on Turbine Trip During Maintenance Activities ENS 431692007-02-15T21:54:00015 February 2007 21:54:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 1 and Unit 2 Reactor Trip ENS 425762006-05-15T14:59:00015 May 2006 14:59:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Momentary Loss of Dhr Due to Automatic Actuation of the Keowee Emergency Power Supply ENS 419662005-08-31T18:28:00031 August 2005 18:28:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Unit 3 Experienced an Automatic Reactor Trip During Routine Testing 2022-05-07T03:10:00 | |