Event Notification Report for May 22, 2008
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
05/21/2008 - 05/22/2008
EVENT NUMBERS
44234
Power Reactor
Event Number: 44234
Facility: MILLSTONE
Region: 1 State: CT
Unit: [] [2] []
RX Type: [1] GE-3,[2] CE,[3] W-4-LP
NRC Notified By: MARIA GHARAKHANIAN
HQ OPS Officer: JOHN KNOKE
Region: 1 State: CT
Unit: [] [2] []
RX Type: [1] GE-3,[2] CE,[3] W-4-LP
NRC Notified By: MARIA GHARAKHANIAN
HQ OPS Officer: JOHN KNOKE
Notification Date: 05/22/2008
Notification Time: 14:35 [ET]
Event Date: 05/22/2008
Event Time: 14:20 [EDT]
Last Update Date: 05/23/2008
Notification Time: 14:35 [ET]
Event Date: 05/22/2008
Event Time: 14:20 [EDT]
Last Update Date: 05/23/2008
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
Person (Organization):
MEL GRAY (R1)
MEL GRAY (R1)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | A/R | Y | 100 | Power Operation | 0 | Hot Standby |
REACTOR TRIP DUE TO LIGHTNING STRIKE
Lightning struck the main transformer for Millstone Unit 2 and caused actuation of the reactor protection system. The reactor had an uncomplicated trip. Reactor shutdown and all control rods fully inserted. No primary or secondary relief valves lifted. Plant is stable in Hot Standby at NOP and NOT. Level is being maintained with normal feedwater and AFW is available if required. Decay heat is being removed via steam bypass valves.
The licensee notified the NRC Resident Inspector.
* * * UPDATE PROVIDED AT 2127 EDT ON 05/23/08 FROM MARK STROLLO TO JEFF ROTTON * * *
"The purpose of this update is to clarify the stated cause of the reactor trip and plant response. The original title was 'Reactor Trip Due to lightning Strike on Main Transformer'. Although there was a lightning storm in the vicinity of Millstone 2 at the time of the reactor trip, the cause of the reactor trip may be related to a grid disturbance caused by a lightning strike on a transmission line off site. This cause remains under investigation. [Initial] event report states that no primary or secondary relief valves lifted. A steam generator safety relief valve (secondary) lifted for about 34 seconds.
"The NRC Sr. Resident Inspector has been notified."
Notified R1DO (Gray).
Lightning struck the main transformer for Millstone Unit 2 and caused actuation of the reactor protection system. The reactor had an uncomplicated trip. Reactor shutdown and all control rods fully inserted. No primary or secondary relief valves lifted. Plant is stable in Hot Standby at NOP and NOT. Level is being maintained with normal feedwater and AFW is available if required. Decay heat is being removed via steam bypass valves.
The licensee notified the NRC Resident Inspector.
* * * UPDATE PROVIDED AT 2127 EDT ON 05/23/08 FROM MARK STROLLO TO JEFF ROTTON * * *
"The purpose of this update is to clarify the stated cause of the reactor trip and plant response. The original title was 'Reactor Trip Due to lightning Strike on Main Transformer'. Although there was a lightning storm in the vicinity of Millstone 2 at the time of the reactor trip, the cause of the reactor trip may be related to a grid disturbance caused by a lightning strike on a transmission line off site. This cause remains under investigation. [Initial] event report states that no primary or secondary relief valves lifted. A steam generator safety relief valve (secondary) lifted for about 34 seconds.
"The NRC Sr. Resident Inspector has been notified."
Notified R1DO (Gray).