Event Notification Report for March 23, 2023
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
03/22/2023 - 03/23/2023
Power Reactor
Event Number: 56429
Facility: Fermi
Region: 3 State: MI
Unit: [2] [] []
RX Type: [2] GE-4
NRC Notified By: Justin Wilhelm
HQ OPS Officer: Donald Norwood
Region: 3 State: MI
Unit: [2] [] []
RX Type: [2] GE-4
NRC Notified By: Justin Wilhelm
HQ OPS Officer: Donald Norwood
Notification Date: 03/23/2023
Notification Time: 18:30 [ET]
Event Date: 03/23/2023
Event Time: 11:45 [EDT]
Last Update Date: 03/27/2023
Notification Time: 18:30 [ET]
Event Date: 03/23/2023
Event Time: 11:45 [EDT]
Last Update Date: 03/27/2023
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(3)(v)(A) - Pot Unable To Safe Sd 50.72(b)(3)(v)(B) - Pot Rhr Inop 50.72(b)(3)(v)(D) - Accident Mitigation
10 CFR Section:
50.72(b)(3)(v)(A) - Pot Unable To Safe Sd 50.72(b)(3)(v)(B) - Pot Rhr Inop 50.72(b)(3)(v)(D) - Accident Mitigation
Person (Organization):
McCraw, Aaron (R3DO)
McCraw, Aaron (R3DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | Y | 100 | Power Operation | 100 | Power Operation |
EN Revision Imported Date: 3/27/2023
EN Revision Text: DESIGN FLAW DISCOVERED IN MECHANICAL DRAFT COOLING TOWER FAN BRAKES
The following information was provided by the licensee via fax:
"While in Mode 1 at 100 percent power 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 a design flaw with the control system. The MDCT fan brakes are required to prevent fan overspeed from a design basis tornado. The MDCT fans are required to support the operability of the ultimate heat sink (UHS).
"At the time of discovery, the provisions of LCO 3.0.9 were being utilized for loss of the 'D' MDCT fan brake (barrier loss). When it was identified the condition was a design flaw common to all MDCT fan brakes, the 24-hour allowance for restoration was entered.
"A design change is currently being implemented to restore MDCT fan brake operability.
"This condition is reportable per 10 CFR 50.72(b)(3)(v)(A), (B), & (D).
"The NRC Resident Inspector has been notified."
EN Revision Text: DESIGN FLAW DISCOVERED IN MECHANICAL DRAFT COOLING TOWER FAN BRAKES
The following information was provided by the licensee via fax:
"While in Mode 1 at 100 percent power 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 a design flaw with the control system. The MDCT fan brakes are required to prevent fan overspeed from a design basis tornado. The MDCT fans are required to support the operability of the ultimate heat sink (UHS).
"At the time of discovery, the provisions of LCO 3.0.9 were being utilized for loss of the 'D' MDCT fan brake (barrier loss). When it was identified the condition was a design flaw common to all MDCT fan brakes, the 24-hour allowance for restoration was entered.
"A design change is currently being implemented to restore MDCT fan brake operability.
"This condition is reportable per 10 CFR 50.72(b)(3)(v)(A), (B), & (D).
"The NRC Resident Inspector has been notified."
Power Reactor
Event Number: 56430
Facility: Susquehanna
Region: 1 State: PA
Unit: [2] [] []
RX Type: [1] GE-4,[2] GE-4
NRC Notified By: Robert Bingman
HQ OPS Officer: Brian P. Smith
Region: 1 State: PA
Unit: [2] [] []
RX Type: [1] GE-4,[2] GE-4
NRC Notified By: Robert Bingman
HQ OPS Officer: Brian P. Smith
Notification Date: 03/23/2023
Notification Time: 20:40 [ET]
Event Date: 03/23/2023
Event Time: 17:36 [EDT]
Last Update Date: 03/27/2023
Notification Time: 20:40 [ET]
Event Date: 03/23/2023
Event Time: 17:36 [EDT]
Last Update Date: 03/27/2023
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(3)(iv)(A) - Valid Specif Sys Actuation
10 CFR Section:
50.72(b)(3)(iv)(A) - Valid Specif Sys Actuation
Person (Organization):
Werkheiser, Dave (R1DO)
Werkheiser, Dave (R1DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | N | 0 | Cold Shutdown | 0 | Cold Shutdown |
EN Revision Imported Date: 3/27/2023
EN Revision Text: EMERGENCY DIESEL GENERATOR ACTUATION
The following information was provided by the licensee via email:
"At 1736 EDT on March 23, 2023, during overcurrent testing of the '2B' [Emergency Safeguards System] ESS Bus, the work group was re-installing tested relays and inadvertently caused a '2B' ESS Bus lockout. This resulted in the '2B' ESS Bus deenergizing and a valid start signal provided to the 'B' Emergency Diesel Generator [EDG]. The 'B' EDG started and functioned as designed.
"This is being reported as an unplanned actuation of systems that mitigate the consequences of significant events in accordance with 10 CFR 50.72(b)(3)(iv)(A).
"The NRC Resident Inspector has been notified."
EN Revision Text: EMERGENCY DIESEL GENERATOR ACTUATION
The following information was provided by the licensee via email:
"At 1736 EDT on March 23, 2023, during overcurrent testing of the '2B' [Emergency Safeguards System] ESS Bus, the work group was re-installing tested relays and inadvertently caused a '2B' ESS Bus lockout. This resulted in the '2B' ESS Bus deenergizing and a valid start signal provided to the 'B' Emergency Diesel Generator [EDG]. The 'B' EDG started and functioned as designed.
"This is being reported as an unplanned actuation of systems that mitigate the consequences of significant events in accordance with 10 CFR 50.72(b)(3)(iv)(A).
"The NRC Resident Inspector has been notified."