Event Notification Report for November 06, 2021
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
11/05/2021 - 11/06/2021
EVENT NUMBERS
55565
55565
Power Reactor
Event Number: 55565
Facility: Millstone
Region: 1 State: CT
Unit: [2] [] []
RX Type: [1] GE-3,[2] CE,[3] W-4-LP
NRC Notified By: Joseph Browning
HQ OPS Officer: Kerby Scales
Region: 1 State: CT
Unit: [2] [] []
RX Type: [1] GE-3,[2] CE,[3] W-4-LP
NRC Notified By: Joseph Browning
HQ OPS Officer: Kerby Scales
Notification Date: 11/06/2021
Notification Time: 13:03 [ET]
Event Date: 11/06/2021
Event Time: 11:00 [EDT]
Last Update Date: 11/06/2021
Notification Time: 13:03 [ET]
Event Date: 11/06/2021
Event Time: 11:00 [EDT]
Last Update Date: 11/06/2021
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(3)(ii)(B) - Unanalyzed Condition
10 CFR Section:
50.72(b)(3)(ii)(B) - Unanalyzed Condition
Person (Organization):
Young, Matt (R1)
Young, Matt (R1)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | N | 0 | Hot Standby | 0 | Hot Standby |
EN Revision Imported Date: 12/6/2021
EN Revision Text: STEAM SUPPLY CHECK FAILURE TO TURBINE DRIVEN AUXILLARY FEEDWATER
"During a Unit 2 refueling outage valve overhaul activity on the steam supply check valve from the number 2 steam generator to the turbine driven auxiliary feedwater pump, 2-MS-4B, the check valve was found with its disc separated from the disc arm. This failure would have resulted in the blowdown of both steam generators during a main steam line break in the steam generator number 2 main steam line upstream of the main steam isolation valves until the operators could isolate the faulted steam generator. On November 6, at approximately 1100 EDT evaluation determined that this condition constituted an unanalyzed condition that could impact containment pressure.
"There has been no radioactive release to the environment. The valve has been repaired. The check valve in the steam supply from the number 1 steam generator to the turbine driven auxiliary feedwater pump was inspected and found to be satisfactory. There has been no impact to Unit 3 which remains at 100% power.
"The NRC Senior Resident has been notified.
"This condition is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(B) as a condition that resulted in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety."
EN Revision Text: STEAM SUPPLY CHECK FAILURE TO TURBINE DRIVEN AUXILLARY FEEDWATER
"During a Unit 2 refueling outage valve overhaul activity on the steam supply check valve from the number 2 steam generator to the turbine driven auxiliary feedwater pump, 2-MS-4B, the check valve was found with its disc separated from the disc arm. This failure would have resulted in the blowdown of both steam generators during a main steam line break in the steam generator number 2 main steam line upstream of the main steam isolation valves until the operators could isolate the faulted steam generator. On November 6, at approximately 1100 EDT evaluation determined that this condition constituted an unanalyzed condition that could impact containment pressure.
"There has been no radioactive release to the environment. The valve has been repaired. The check valve in the steam supply from the number 1 steam generator to the turbine driven auxiliary feedwater pump was inspected and found to be satisfactory. There has been no impact to Unit 3 which remains at 100% power.
"The NRC Senior Resident has been notified.
"This condition is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(B) as a condition that resulted in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety."