ENS 47660
ENS Event | |
|---|---|
13:34 Feb 12, 2012 | |
| Title | Unusual Event Due to Electrical Fault in 161 Kv Switchyard |
| Event Description | At 0756 [EST] on 2/12/12, an electrical event occurred in the 161 kV switchyard that resulted in bus differential relay operating, and opening all PCBs [Protective Circuit Breakers] within 161 kV bus 2-2. Shortly after, a call was received from site security regarding an explosion in the switchyard.
At 0820, a report was received that visible damage was present on an insulator between a PCB and a Motor Operated Disconnect (MOD) in the 161 kV switchyard, which is where the fault occurred. Follow up reports indicated an oil leak from a current transformer. Two other PCBs were identified to have visible damage. After the event, while opening MODS for PCBs that tripped open, the 'A' phase for one MOD did not open. No safety related equipment required to establish or maintain safe shutdown was affected. All the Diesel Generators remain in operable standby conditions. Unit 1 remained steady at 100% with no transients. Unit 2 had a 2B Condenser Circ Water pump trip off. Crew responded to the pump trip and Unit 2 remains at 100%. One offsite power source is inoperable and second offsite power source has been verified operable. Grid status is Yellow. There were no personnel injuries reported due to the fault and resulting explosion. The loss of the offsite power source resulted in the licensee entering a 72-hr. LCO. The licensee is investigating both the cause of loss of offsite power and the circulating water pump trip. The licensee has notified the State of Tennessee and the NRC Resident Inspector.
At 1019 EST, the licensee terminated their Notification of Unusual Event. The basis for termination was that the fault was cleared and the conditions for EAL entry no longer exists. The licensee has made state and local notifications and has notified the NRC Resident Inspector. Notified R2DO (Calle), IRD (Kozal), NRR (Evans), DHS (Beach), FEMA (Fuller), and NICC (Berger) |
| Where | |
|---|---|
Sequoyah  Tennessee (NRC Region 2) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration | |
| Time - Person (Reporting Time:+-4.13 h-0.172 days <br />-0.0246 weeks <br />-0.00566 months <br />) | |
| Opened: | Tim Reed 09:26 Feb 12, 2012 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Feb 12, 2012 |
| 47660 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 558662022-04-29T03:55:00029 April 2022 03:55:00
[Table view]10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notice of Unusual Event ENS 537542018-11-26T05:00:00026 November 2018 05:00:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared for Excessive Smoke in Containment ENS 476602012-02-12T13:34:00012 February 2012 13:34:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Due to Electrical Fault in 161 Kv Switchyard ENS 462702010-09-23T01:54:00023 September 2010 01:54:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event Due to a Transformer Fire ENS 401132003-08-28T20:04:00028 August 2003 20:04:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Alert Declared Due to Reactor Protection System Failure 2022-04-29T03:55:00 | |