Event Notification Report for December 26, 2010
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
12/25/2010 - 12/26/2010
EVENT NUMBERS
46511
Power Reactor
Event Number: 46511
Facility: BROWNS FERRY
Region: 2 State: AL
Unit: [] [] [3]
RX Type: [1] GE-4,[2] GE-4,[3] GE-4
NRC Notified By: TIMOTHY SCOTT
HQ OPS Officer: DONALD NORWOOD
Region: 2 State: AL
Unit: [] [] [3]
RX Type: [1] GE-4,[2] GE-4,[3] GE-4
NRC Notified By: TIMOTHY SCOTT
HQ OPS Officer: DONALD NORWOOD
Notification Date: 12/26/2010
Notification Time: 20:53 [ET]
Event Date: 12/26/2010
Event Time: 16:20 [CST]
Last Update Date: 12/26/2010
Notification Time: 20:53 [ET]
Event Date: 12/26/2010
Event Time: 16:20 [CST]
Last Update Date: 12/26/2010
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):
DAVID AYRES (R2DO)
DAVID AYRES (R2DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 3 | M/R | Y | 100 | Power Operation | 0 | Hot Shutdown |
MANUAL REACTOR SCRAM DUE TO HIGH VIBRATION ON MAIN GENERATOR EXCITER
"On 12/26/2010 at 1620 CST, Browns Ferry Unit 3 initiated a manual reactor SCRAM due to high vibration on the Unit 3 Generator Exciter inboard and outboard journal bearings. All plant systems responded as required to the manual SCRAM signal. No Emergency Core Cooling System (ECCS) initiations occurred as a result of the manual SCRAM signal. Reactor water level lowered below Level 3 (+2") as a result of the SCRAM and was recovered to the normal water level band by the Reactor Feed Pumps (RFPs). The expected Primary Containment Isolation System (PCIS) groups 2, 3, 6, and 8 isolations were received due to reactor water level lowering below Level 3 (+2") with all systems isolating as required. There were no indications of main steam relief valves (MSRVs) opening.
"The manual scram from critical is reportable within four hours under 10CFR50.72(b)(2)(iv)(B), 'Any event or condition that results in a valid actuation of the Reactor Protection System' and within eight hours under 10CFR50.72(b)(3)(iv)(A), 'Any event that results in an actuation of the specified systems.' The manual scram from critical also requires a 60-day written report in accordance with 10CFR50.73(a)(2)(iv)(A).
"The event was entered into the licensee corrective action program as Problem Evaluation Report 301505.
"The NRC Resident Inspector was informed."
All control rods fully inserted. Plant is in a normal post-scram electrical alignment. Decay heat is being removed through the turbine bypass valves to the main condenser.
"On 12/26/2010 at 1620 CST, Browns Ferry Unit 3 initiated a manual reactor SCRAM due to high vibration on the Unit 3 Generator Exciter inboard and outboard journal bearings. All plant systems responded as required to the manual SCRAM signal. No Emergency Core Cooling System (ECCS) initiations occurred as a result of the manual SCRAM signal. Reactor water level lowered below Level 3 (+2") as a result of the SCRAM and was recovered to the normal water level band by the Reactor Feed Pumps (RFPs). The expected Primary Containment Isolation System (PCIS) groups 2, 3, 6, and 8 isolations were received due to reactor water level lowering below Level 3 (+2") with all systems isolating as required. There were no indications of main steam relief valves (MSRVs) opening.
"The manual scram from critical is reportable within four hours under 10CFR50.72(b)(2)(iv)(B), 'Any event or condition that results in a valid actuation of the Reactor Protection System' and within eight hours under 10CFR50.72(b)(3)(iv)(A), 'Any event that results in an actuation of the specified systems.' The manual scram from critical also requires a 60-day written report in accordance with 10CFR50.73(a)(2)(iv)(A).
"The event was entered into the licensee corrective action program as Problem Evaluation Report 301505.
"The NRC Resident Inspector was informed."
All control rods fully inserted. Plant is in a normal post-scram electrical alignment. Decay heat is being removed through the turbine bypass valves to the main condenser.