ENS 55733
ENS Event | |
|---|---|
08:57 Feb 5, 2022 | |
| Title | Unusual Event Declared Due to Visual Observation of Smoke and Multiple Fire Alarms in the West Penetration Room |
| Event Description | The following information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
At 0357 EST on 2/5/22, Oconee Unit 2 declared an Unusual Event due to a multiple fire alarms and visual observance of a smoke filled room in the West Penetration Room (EAL HU 4.1). Unit 2 automatically tripped and entered Mode 3. There was an indication that a release to the environment potentially occurred. Units 1 and 3 remained at 100% power. The Licensee notified the NRC Resident Inspector, the State, and local authorities. Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), and DHS Nuclear SSA (email).
The following information was provided by the licensee via email: At 0343 EST on February 5th, 2022, with Unit 2 in Mode 1 at 100% power, the reactor automatically tripped due to Reactor Coolant Pump (RCP) Flux/Flow Imbalance caused by the simultaneous trip of all 4 RCPs. The cause of the loss of all RCPs is under investigation. The trip was not complex. There was no inoperable equipment prior to the event that contributed to it. Operations responded and stabilized the plant. Decay heat is being removed by the Reactor Coolant System (RCS) in natural circulation with normal feedwater flow. Due to the Reactor Protection System (RPS) actuation while critical, this event is being reported as a four hour, nonemergency notification per 10 CFR 50.72(b)(2)(iv)(B). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The Licensee notified the State and local authorities. Notified R2DO (Miller)
The following information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: At 0811 EST on 2/5/22, Oconee Unit 2 terminated the notification of unusual event because EAL HU 4.1 criteria were no longer met. Unit 2 remains shutdown in Mode 3. The licensee has notified the State and local authorities and will notify the NRC Resident Inspector. Notified R2DO (Miller), IRD MOC (Gott), NRR EO (Regan), DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).
The following information was provided by the licensee via email: The follow-up investigation determine that the cause of the trip was determined to be a failed fuse in an undervoltage monitoring circuit for the electrical bus powering the reactor coolant pumps. The trip of the reactor coolant pumps resulted in an automatic reactor trip as designed. The plant responded as expected. There was no fire. The response of the main feedwater system caused an expected increase in temperature in a standby portion of the system which caused the breakdown of the pipe coating producing smoke. There was no release to the environment. The reading of a single instrument was determined to be invalid and other indications supported the conclusion that no release occurred. The following information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The Licensee notified the NRC Resident Inspector, State and local authorities. A media release was issued on 2/5/22. Notified R2DO (Miller), IRD MOC (Gott), NRR EO (Regan). |
| 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:+-4.42 h-0.184 days <br />-0.0263 weeks <br />-0.00605 months <br />) | |
| Opened: | Christopher Tam 04:32 Feb 5, 2022 |
| NRC Officer: | Lloyd Desotell |
| Last Updated: | Feb 8, 2022 |
| 55733 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
WEEKMONTHYEARENS 557332022-02-05T08:57:0005 February 2022 08:57:00
[Table view]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 2022-02-05T08:57:00 | |