Event Notification Report for November 27, 2021
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
11/26/2021 - 11/27/2021
EVENT NUMBERS
55612
55612
Power Reactor
Event Number: 55612
Facility: Oconee
Region: 2 State: SC
Unit: [2] [] []
RX Type: [1] B&W-L-LP,[2] B&W-L-LP,[3] B&W-L-LP
NRC Notified By: Will Beekman
HQ OPS Officer: Howie Crouch
Region: 2 State: SC
Unit: [2] [] []
RX Type: [1] B&W-L-LP,[2] B&W-L-LP,[3] B&W-L-LP
NRC Notified By: Will Beekman
HQ OPS Officer: Howie Crouch
Notification Date: 11/27/2021
Notification Time: 13:16 [ET]
Event Date: 11/27/2021
Event Time: 05:19 [EST]
Last Update Date: 11/27/2021
Notification Time: 13:16 [ET]
Event Date: 11/27/2021
Event Time: 05:19 [EST]
Last Update Date: 11/27/2021
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(3)(iv)(A) - Valid Specif Sys Actuation 50.72(b)(3)(v)(B) - Pot Rhr Inop
10 CFR Section:
50.72(b)(3)(iv)(A) - Valid Specif Sys Actuation 50.72(b)(3)(v)(B) - Pot Rhr Inop
Person (Organization):
Miller, Mark (R2)
Miller, Mark (R2)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | N | 0 | Cold Shutdown | 0 | Cold Shutdown |
EN Revision Imported Date: 12/27/2021
EN Revision Text: AUTOMATIC ACTUATION OF THE EMERGENCY AC ELECTRICAL POWER SYSTEM
"At 0519 EST on November 27, 2021, with Unit 2 in Mode 5 at zero percent power, an actuation of the Emergency AC Electrical Power System occurred. The reason for the Emergency AC Electrical Power System auto-start was a lockout of the CT-2 transformer; causing a temporary loss of AC power to the main feeder bus. The Keowee Hydroelectric Units 1 and 2 automatically started as designed when a main feeder bus undervoltage signal was received.
"This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the Emergency AC Electrical Power System.
"Additionally, the temporary loss of AC power resulted in a loss of Decay Heat Removal (DHR) that was restored upon power restoration to the main feeder bus. Therefore, this condition is also being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v) for an event or condition that could have prevented fulfillment of a safety function.
"There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified."
The loss of the CT-2 transformer is under investigation. Main feeder bus power was restored within a minute so no plant heat up occurred as a result of the loss of the decay heat removal system.
EN Revision Text: AUTOMATIC ACTUATION OF THE EMERGENCY AC ELECTRICAL POWER SYSTEM
"At 0519 EST on November 27, 2021, with Unit 2 in Mode 5 at zero percent power, an actuation of the Emergency AC Electrical Power System occurred. The reason for the Emergency AC Electrical Power System auto-start was a lockout of the CT-2 transformer; causing a temporary loss of AC power to the main feeder bus. The Keowee Hydroelectric Units 1 and 2 automatically started as designed when a main feeder bus undervoltage signal was received.
"This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the Emergency AC Electrical Power System.
"Additionally, the temporary loss of AC power resulted in a loss of Decay Heat Removal (DHR) that was restored upon power restoration to the main feeder bus. Therefore, this condition is also being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v) for an event or condition that could have prevented fulfillment of a safety function.
"There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified."
The loss of the CT-2 transformer is under investigation. Main feeder bus power was restored within a minute so no plant heat up occurred as a result of the loss of the decay heat removal system.