Event Notification Report for September 17, 2005
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
09/16/2005 - 09/17/2005
EVENT NUMBERS
41997
Power Reactor
Event Number: 41997
Facility: BROWNS FERRY
Region: 2 State: AL
Unit: [] [] [3]
RX Type: [1] GE-4,[2] GE-4,[3] GE-4
NRC Notified By: MIKE MORROW
HQ OPS Officer: BILL GOTT
Region: 2 State: AL
Unit: [] [] [3]
RX Type: [1] GE-4,[2] GE-4,[3] GE-4
NRC Notified By: MIKE MORROW
HQ OPS Officer: BILL GOTT
Notification Date: 09/17/2005
Notification Time: 16:07 [ET]
Event Date: 09/17/2005
Event Time: 11:29 [CDT]
Last Update Date: 09/17/2005
Notification Time: 16:07 [ET]
Event Date: 09/17/2005
Event Time: 11:29 [CDT]
Last Update Date: 09/17/2005
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
JOEL MUNDAY (R2)
JOEL MUNDAY (R2)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 3 | A/R | Y | 74 | Power Operation | 0 | Hot Shutdown |
REACTOR SCRAM DUE TO MAINTENANCE
"On 09/17/2005 at 1129 CDT, Browns Ferry Unit 3 reactor automatically scrammed due to the trip of the main generator turbine on low main condenser vacuum. Prior to the trip, the unit was operating at reduced power (74 percent) and maintenance was in progress to repair in place a secondary plant moisture separator level control valve. This maintenance activity resulted in the low condenser vacuum condition.
"Plant response to the scram was as expected. Post-scram transient RPV low water level caused a valid automatic initiation of primary containment isolation (PCIS) valves group 2 (containment sumps and shutdown cooling valves), group 3 (reactor water cleanup system), group 6 (ventilation systems, including initiation of standby gas treatment and control room emergency ventilation systems), and group 8 (traversing in-core probe system).
"This event is reportable to the NRC via ENS within four hours under 10CFR50.72(b)(2)(iv)(B) (RPS actuation while critical), and within eight hours under 10CFR50.72(b)(3)(iv)(A) (RPS and containment isolation actuation)."
Browns Ferry Unit 2 was not affected. The reactor shutdown and all control rods fully inserted. Condenser vacuum has been restored and decay heat is being removed using the bypass valves.
"On 09/17/2005 at 1129 CDT, Browns Ferry Unit 3 reactor automatically scrammed due to the trip of the main generator turbine on low main condenser vacuum. Prior to the trip, the unit was operating at reduced power (74 percent) and maintenance was in progress to repair in place a secondary plant moisture separator level control valve. This maintenance activity resulted in the low condenser vacuum condition.
"Plant response to the scram was as expected. Post-scram transient RPV low water level caused a valid automatic initiation of primary containment isolation (PCIS) valves group 2 (containment sumps and shutdown cooling valves), group 3 (reactor water cleanup system), group 6 (ventilation systems, including initiation of standby gas treatment and control room emergency ventilation systems), and group 8 (traversing in-core probe system).
"This event is reportable to the NRC via ENS within four hours under 10CFR50.72(b)(2)(iv)(B) (RPS actuation while critical), and within eight hours under 10CFR50.72(b)(3)(iv)(A) (RPS and containment isolation actuation)."
Browns Ferry Unit 2 was not affected. The reactor shutdown and all control rods fully inserted. Condenser vacuum has been restored and decay heat is being removed using the bypass valves.