Event Notification Report for May 25, 2023
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
05/24/2023 - 05/25/2023
Power Reactor
Event Number: 56541
Facility: Watts Bar
Region: 2 State: TN
Unit: [2] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: Joanne Dehay
HQ OPS Officer: Ian Howard
Region: 2 State: TN
Unit: [2] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: Joanne Dehay
HQ OPS Officer: Ian Howard
Notification Date: 05/25/2023
Notification Time: 17:02 [ET]
Event Date: 05/25/2023
Event Time: 13:45 [EDT]
Last Update Date: 05/25/2023
Notification Time: 17:02 [ET]
Event Date: 05/25/2023
Event Time: 13:45 [EDT]
Last Update Date: 05/25/2023
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):
Miller, Mark (R2DO)
Miller, Mark (R2DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | Y | 100 | Power Operation | 100 | Power Operation |
UNANALYZED CONDITION OF EMERGENCY DIESEL GENERATOR
The following information was provided by the licensee via phone and email:
"At 1345 EDT on May 25, 2023, it was determined that a fire barrier for area 737-A1B was not installed, and would render the 2A Emergency Diesel Generator (EDG) not operable in the event of a fire on the Unit 2 side of elevation 737 in the Auxiliary Building. The 2A EDG is the credited power source for fire safe shutdown for a fire located in this area. Without the credited source of power, this places WBN U2 [Watts Bar Nuclear Unit 2] in an unanalyzed condition. A fire watch has been established in the area until the issue is resolved. Therefore, this event is being reported as an eight-hour non-emergency notification per 10 CFR 50.72(b)(3)(ii)(B).
"The NRC Resident Inspector has been notified."
The following information was provided by the licensee via phone and email:
"At 1345 EDT on May 25, 2023, it was determined that a fire barrier for area 737-A1B was not installed, and would render the 2A Emergency Diesel Generator (EDG) not operable in the event of a fire on the Unit 2 side of elevation 737 in the Auxiliary Building. The 2A EDG is the credited power source for fire safe shutdown for a fire located in this area. Without the credited source of power, this places WBN U2 [Watts Bar Nuclear Unit 2] in an unanalyzed condition. A fire watch has been established in the area until the issue is resolved. Therefore, this event is being reported as an eight-hour non-emergency notification per 10 CFR 50.72(b)(3)(ii)(B).
"The NRC Resident Inspector has been notified."
Power Reactor
Event Number: 56542
Facility: Fermi
Region: 3 State: MI
Unit: [2] [] []
RX Type: [2] GE-4
NRC Notified By: Eric Frank
HQ OPS Officer: Donald Norwood
Region: 3 State: MI
Unit: [2] [] []
RX Type: [2] GE-4
NRC Notified By: Eric Frank
HQ OPS Officer: Donald Norwood
Notification Date: 05/26/2023
Notification Time: 14:16 [ET]
Event Date: 05/25/2023
Event Time: 00:00 [EDT]
Last Update Date: 05/26/2023
Notification Time: 14:16 [ET]
Event Date: 05/25/2023
Event Time: 00:00 [EDT]
Last Update Date: 05/26/2023
Emergency Class: Non Emergency
10 CFR Section:
21.21(a)(2) - Interim Eval Of Deviation
10 CFR Section:
21.21(a)(2) - Interim Eval Of Deviation
Person (Organization):
Benjamin, Jamie (R3DO)
Part 21/50.55 Reactors, - (EMAIL)
Benjamin, Jamie (R3DO)
Part 21/50.55 Reactors, - (EMAIL)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | Y | 100 | Power Operation | 100 | Power Operation |
PART 21 INTERIM EVALUATION - MECHANICAL DRAFT COOLING TOWER FAN BRAKES DESIGN FLAW
The following is a summary of the information provided by the licensee via email:
"As previously reported under Fermi LER 2023-001-00, submitted on May 22, 2023, at 1145 EDT on March 23, 2023, it was determined that all mechanical draft cooling tower (MDCT) fan brakes would not perform their design function during a tornado due to the speed switch not functioning over its published voltage and frequency ranges. The MDCT fan brakes are required to prevent fan overspeed from a design basis tornado. On May 25, 2023, Fermi completed its 10 CFR Part 21 discovery process and determined the need to perform a 10 CFR Part 21 evaluation. The vendor (Engine Systems Inc. (ESI)) was contacted and the purchaser (Fermi) assumed responsibility for performing the Part 21 evaluation for the supplied mechanism. This Part 21 evaluation is being tracked by Fermi CARD 23-20075.
"It has been determined the direct cause of the event was due to the Dynalco speed switch model SST-2400A-1, supplied by ESI, not functioning over its published voltage and frequency ranges. Corrective actions were taken to develop a design change to correct MDCT fan speed control system returning the MDCT fans, ultimate heat sink, and the service water subsystems to service on March 24, 2023. The root cause evaluation is ongoing, and written follow-up will be provided in 30 days by providing a supplement to the original LER by June 24, 2023.
"No new commitments are being made in this submittal."
The following is a summary of the information provided by the licensee via email:
"As previously reported under Fermi LER 2023-001-00, submitted on May 22, 2023, at 1145 EDT on March 23, 2023, it was determined that all mechanical draft cooling tower (MDCT) fan brakes would not perform their design function during a tornado due to the speed switch not functioning over its published voltage and frequency ranges. The MDCT fan brakes are required to prevent fan overspeed from a design basis tornado. On May 25, 2023, Fermi completed its 10 CFR Part 21 discovery process and determined the need to perform a 10 CFR Part 21 evaluation. The vendor (Engine Systems Inc. (ESI)) was contacted and the purchaser (Fermi) assumed responsibility for performing the Part 21 evaluation for the supplied mechanism. This Part 21 evaluation is being tracked by Fermi CARD 23-20075.
"It has been determined the direct cause of the event was due to the Dynalco speed switch model SST-2400A-1, supplied by ESI, not functioning over its published voltage and frequency ranges. Corrective actions were taken to develop a design change to correct MDCT fan speed control system returning the MDCT fans, ultimate heat sink, and the service water subsystems to service on March 24, 2023. The root cause evaluation is ongoing, and written follow-up will be provided in 30 days by providing a supplement to the original LER by June 24, 2023.
"No new commitments are being made in this submittal."