Event Notification Report for December 28, 2023
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
12/27/2023 - 12/28/2023
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
Power Reactor
Event Number: 56910
Facility: Watts Bar
Region: 2 State: TN
Unit: [1] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: Tony Pate
HQ OPS Officer: Adam Koziol
Region: 2 State: TN
Unit: [1] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: Tony Pate
HQ OPS Officer: Adam Koziol
Notification Date: 12/28/2023
Notification Time: 18:55 [ET]
Event Date: 12/28/2023
Event Time: 11:29 [EST]
Last Update Date: 01/04/2024
Notification Time: 18:55 [ET]
Event Date: 12/28/2023
Event Time: 11:29 [EST]
Last Update Date: 01/04/2024
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 |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
| 2 | N | Y | 100 | Power Operation | 100 | Power Operation |
EN Revision Imported Date: 1/5/2024
EN Revision Text: UNANALYZED CONDITION
The following information was provided by the licensee via email:
"Plant alignment caused an unanalyzed condition regarding unit 1 and unit 2 Appendix R procedures.
"[Watts Bar Nuclear] (WBN) unit 1 and unit 2 Appendix R procedures require manual operator action times including [volume control tank] (VCT) isolation. They are calculated with an assumed hydrogen cover gas constant at 20 psig. This is to preclude hydrogen ingestion into the charging pumps with an operator action time of 70 minutes. Due to recent lower hydrogen concentration in the [reactor coolant system] (RCS), [unit 2] VCT hydrogen regulator set point was increased to 28 psig. This increased pressure set point invalidated the initial assumptions made in the Appendix R calculations for manual operator action times.
"WBN unit 1 VCT hydrogen regulator was also verified high out of band at 22 psig.
"WBN has restored unit 1 and unit 2 VCT hydrogen regulators to the required specification.
"The NRC Resident Inspector has been notified of this condition."
* * * RETRACTION ON 1/4/24 AT 1556 EST FROM JARRETT K. LAVASSEUR TO OSSY FONT * * *
The following information was provided by the licensee via email:
"In accordance with NUREG-1022, Section 2.8 and Section 4.2.3, WBN is retracting the previous report in EN 56910 pursuant to 10 CFR 50.72(b)(3)(ii)(B). An analysis of the postulated Appendix R Fires that could cause ingestion of cover gas into the charging pumps would be mitigated through current plant processes and procedures and therefore does not present a significant threat to fire safe shutdown. Based on sufficient margin and existing operator actions, the event does not represent a condition that significantly degrades plant safety under 10 CFR 50.72(b)(3)(ii)(B). Therefore EN 56910 is being retracted.
"The NRC Resident Inspector has been notified of this retraction."
Notified R2DO (Miller).
EN Revision Text: UNANALYZED CONDITION
The following information was provided by the licensee via email:
"Plant alignment caused an unanalyzed condition regarding unit 1 and unit 2 Appendix R procedures.
"[Watts Bar Nuclear] (WBN) unit 1 and unit 2 Appendix R procedures require manual operator action times including [volume control tank] (VCT) isolation. They are calculated with an assumed hydrogen cover gas constant at 20 psig. This is to preclude hydrogen ingestion into the charging pumps with an operator action time of 70 minutes. Due to recent lower hydrogen concentration in the [reactor coolant system] (RCS), [unit 2] VCT hydrogen regulator set point was increased to 28 psig. This increased pressure set point invalidated the initial assumptions made in the Appendix R calculations for manual operator action times.
"WBN unit 1 VCT hydrogen regulator was also verified high out of band at 22 psig.
"WBN has restored unit 1 and unit 2 VCT hydrogen regulators to the required specification.
"The NRC Resident Inspector has been notified of this condition."
* * * RETRACTION ON 1/4/24 AT 1556 EST FROM JARRETT K. LAVASSEUR TO OSSY FONT * * *
The following information was provided by the licensee via email:
"In accordance with NUREG-1022, Section 2.8 and Section 4.2.3, WBN is retracting the previous report in EN 56910 pursuant to 10 CFR 50.72(b)(3)(ii)(B). An analysis of the postulated Appendix R Fires that could cause ingestion of cover gas into the charging pumps would be mitigated through current plant processes and procedures and therefore does not present a significant threat to fire safe shutdown. Based on sufficient margin and existing operator actions, the event does not represent a condition that significantly degrades plant safety under 10 CFR 50.72(b)(3)(ii)(B). Therefore EN 56910 is being retracted.
"The NRC Resident Inspector has been notified of this retraction."
Notified R2DO (Miller).
Power Reactor
Event Number: 56988
Facility: Brunswick
Region: 2 State: NC
Unit: [2] [] []
RX Type: [1] GE-4,[2] GE-4
NRC Notified By: Chris Denton
HQ OPS Officer: Ernest West
Region: 2 State: NC
Unit: [2] [] []
RX Type: [1] GE-4,[2] GE-4
NRC Notified By: Chris Denton
HQ OPS Officer: Ernest West
Notification Date: 02/22/2024
Notification Time: 08:55 [ET]
Event Date: 12/28/2023
Event Time: 08:15 [EST]
Last Update Date: 02/26/2024
Notification Time: 08:55 [ET]
Event Date: 12/28/2023
Event Time: 08:15 [EST]
Last Update Date: 02/26/2024
Emergency Class: Non Emergency
10 CFR Section:
50.73(a)(1) - Invalid Specif System Actuation
10 CFR Section:
50.73(a)(1) - Invalid Specif System Actuation
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 |
EN Revision Imported Date: 2/26/2024
EN Revision Text: INVALID ACTUATION OF EMERGENCY DIESEL GENERATORS
The following information was provided by the licensee via phone and email:
"This 60-day optional telephone notification is being made in lieu of a Licensee Event Report (LER) submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B).
"At approximately 0815 EST on December 28, 2023, an invalid actuation of the four emergency diesel generators (EDGs) occurred. It was determined that this condition was likely caused by spurious operation of the undervoltage relay for the startup auxiliary transformer feeder breaker to the `1D' balance of plant bus which was being fed by the unit auxiliary transformer at the time, per the normal lineup. This non-safety related EDG actuation logic was disabled, and additional investigation is planned during the upcoming refueling outage.
"The actuation was not initiated in response to actual plant conditions, it was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the system. Therefore, this event has been determined to be an invalid actuation.
"During this event, the four EDGs functioned successfully, and the actuations were complete. All emergency buses remained energized from offsite power and, therefore, the EDGs did not tie to their respective buses.
"This event did not result in any adverse impact to the health and safety of the public."
The NRC Resident Inspector had been notified.
EN Revision Text: INVALID ACTUATION OF EMERGENCY DIESEL GENERATORS
The following information was provided by the licensee via phone and email:
"This 60-day optional telephone notification is being made in lieu of a Licensee Event Report (LER) submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B).
"At approximately 0815 EST on December 28, 2023, an invalid actuation of the four emergency diesel generators (EDGs) occurred. It was determined that this condition was likely caused by spurious operation of the undervoltage relay for the startup auxiliary transformer feeder breaker to the `1D' balance of plant bus which was being fed by the unit auxiliary transformer at the time, per the normal lineup. This non-safety related EDG actuation logic was disabled, and additional investigation is planned during the upcoming refueling outage.
"The actuation was not initiated in response to actual plant conditions, it was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the system. Therefore, this event has been determined to be an invalid actuation.
"During this event, the four EDGs functioned successfully, and the actuations were complete. All emergency buses remained energized from offsite power and, therefore, the EDGs did not tie to their respective buses.
"This event did not result in any adverse impact to the health and safety of the public."
The NRC Resident Inspector had been notified.