Event Notification Report for April 22, 2016
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
04/21/2016 - 04/22/2016
EVENT NUMBERS
51878
Power Reactor
Event Number: 51878
Facility: BROWNS FERRY
Region: 2 State: AL
Unit: [1] [2] []
RX Type: [1] GE-4,[2] GE-4,[3] GE-4
NRC Notified By: MARK MOEBES
HQ OPS Officer: JOHN SHOEMAKER
Region: 2 State: AL
Unit: [1] [2] []
RX Type: [1] GE-4,[2] GE-4,[3] GE-4
NRC Notified By: MARK MOEBES
HQ OPS Officer: JOHN SHOEMAKER
Notification Date: 04/22/2016
Notification Time: 18:22 [ET]
Event Date: 04/22/2016
Event Time: 13:59 [CDT]
Last Update Date: 04/22/2016
Notification Time: 18:22 [ET]
Event Date: 04/22/2016
Event Time: 13:59 [CDT]
Last Update Date: 04/22/2016
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
10 CFR Section:
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
GERALD MCCOY (R2DO)
GERALD MCCOY (R2DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
| 2 | N | Y | 100 | Power Operation | 100 | Power Operation |
PARTIAL LOSS OF POWER EXPERIENCED DURING ELECTRICAL BUS TRANSFER
"At 1359 CDT on April 22, 2016, Browns Ferry Units 1 & 2 experienced a partial loss of power during the transfer of Shutdown Bus 2 from the alternate power source back to the normal power source. During the transfer, the normal feeder breaker failed to close and provide power to the Shutdown Bus, resulting in an auto actuation of two Emergency Diesel Generators (EDGs). Power to Shutdown Bus 2 was immediately restored using the alternate feeder breaker. The EDGs did not tie to the boards.
"All systems responded as expected for the loss of power, and both Units 1 & 2 maintained 100% Rx Power. All systems have been restored to a normal lineup, and both Units 1 & 2 remain at 100% Rx Power.
"This event requires an 8 hour report per 10 CFR 50.72(b)(3)(iv)(A), 'Any event or condition that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B), (8) Emergency AC electrical power systems, including: Emergency diesel generators (EDGs).'
"The NRC resident inspector has been notified."
The cause of the normal feeder breaker failure is being investigated. There was no impact on Unit 3.
"At 1359 CDT on April 22, 2016, Browns Ferry Units 1 & 2 experienced a partial loss of power during the transfer of Shutdown Bus 2 from the alternate power source back to the normal power source. During the transfer, the normal feeder breaker failed to close and provide power to the Shutdown Bus, resulting in an auto actuation of two Emergency Diesel Generators (EDGs). Power to Shutdown Bus 2 was immediately restored using the alternate feeder breaker. The EDGs did not tie to the boards.
"All systems responded as expected for the loss of power, and both Units 1 & 2 maintained 100% Rx Power. All systems have been restored to a normal lineup, and both Units 1 & 2 remain at 100% Rx Power.
"This event requires an 8 hour report per 10 CFR 50.72(b)(3)(iv)(A), 'Any event or condition that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B), (8) Emergency AC electrical power systems, including: Emergency diesel generators (EDGs).'
"The NRC resident inspector has been notified."
The cause of the normal feeder breaker failure is being investigated. There was no impact on Unit 3.