ENS 57711
ENS Event | |
|---|---|
22:28 May 15, 2025 | |
| Title | Unusual Event - Loss of All Offsite Power |
| Event Description | The following information was provided by the licensee via phone and email:
At time 1828 EDT on 5/15/25, Oconee declared an Unusual Event (SU1.1) due to a loss of all offsite power for greater than 15 minutes. This occurred when the site lost their startup transformers (CT 2&3). At the time of the event, the site was restoring from switchyard maintenance and was experiencing a loss of their overhead powerline from the Keowee Hydropower Station. The underground powerline remains operable as a source of emergency power. Units 1, 2, and 3 remain at 100 percent power with Unit 1 being unaffected by this event. Units 2 and 3 are being powered by their auxiliary transformers. State and local agencies were notified. The NRC Resident Inspector has been notified. Notified DHS SWO, FEMA Operations Center, CISA Central Watch Officer, FEMA NWC, DHS Nuclear SSA (email), CWMD Watch Desk (email).
At time 0045, on 5/16/25, Oconee terminated their Unusual Event (SU1.1) due to restoring offsite power (CT 2&3 have been restored). The NRC Senior Resident Inspector has been informed. Notified R2DO (Desai), IR MOC (Grant), NRR EO (Felts). External notifications: DHS SWO, FEMA Operations Center, CISA Central Watch Officer, FEMA NWC, DHS Nuclear SSA (email), CWMD Watch Desk (email). |
| Where | |
|---|---|
Oconee  South Carolina (NRC Region 2) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration | |
| Time - Person (Reporting Time:+-3.57 h-0.149 days <br />-0.0212 weeks <br />-0.00489 months <br />) | |
| Opened: | Alan Hoglen 18:54 May 15, 2025 |
| NRC Officer: | Jordan Wingate |
| Last Updated: | May 16, 2025 |
| 57711 - NRC Website
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WEEKMONTHYEARENS 579142025-09-10T16:07:00010 September 2025 16:07:00
[Table view]10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event - RCS Identified Leakage Greater than 25 Gpm for Greater than 15 Minutes ENS 577112025-05-15T22:28:00015 May 2025 22:28:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event - Loss of All Offsite Power ENS 557332022-02-05T08:57:0005 February 2022 08:57:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Visual Observation of Smoke and Multiple Fire Alarms in the West Penetration Room ENS 533962018-05-10T20:17:00010 May 2018 20:17:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event ENS 517702016-03-06T20:20:0006 March 2016 20:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Emergency Declaration Due to Fire/Explosion in the Main Transformer ENS 510262015-04-30T22:40:00030 April 2015 22:40:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Electrical Fault ENS 461672010-08-11T16:07:00011 August 2010 16:07:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unit 3 Declared an Unusual Event Due to Loss of Annunciators ENS 411372004-10-20T02:10:00020 October 2004 02:10:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Unexplained Decrease in Spent Fuel Pool Water Level ENS 404242004-01-03T01:38:0003 January 2004 01:38:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unit 1 Declared an Unusual Event Due to 14 Gpm Unidentified Rcs Leakage 2025-09-10T16:07:00 | |