Event Notification Report for October 29, 2024
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
10/28/2024 - 10/29/2024
Power Reactor
Event Number: 57404
Facility: Prairie Island
Region: 3 State: MN
Unit: [2] [] []
RX Type: [1] W-2-LP,[2] W-2-LP
NRC Notified By: Martin Cabiro
HQ OPS Officer: Ernest West
Region: 3 State: MN
Unit: [2] [] []
RX Type: [1] W-2-LP,[2] W-2-LP
NRC Notified By: Martin Cabiro
HQ OPS Officer: Ernest West
Notification Date: 10/29/2024
Notification Time: 13:50 [ET]
Event Date: 10/29/2024
Event Time: 10:23 [CDT]
Last Update Date: 10/29/2024
Notification Time: 13:50 [ET]
Event Date: 10/29/2024
Event Time: 10:23 [CDT]
Last Update Date: 10/29/2024
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS Actuation - Critical 50.72(b)(3)(iv)(A) - Valid Specif Sys Actuation
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS Actuation - Critical 50.72(b)(3)(iv)(A) - Valid Specif Sys Actuation
Person (Organization):
Edwards, Rhex (R3DO)
Edwards, Rhex (R3DO)
| 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 |
AUTOMATIC REACTOR TRIP
The following information was provided by the licensee via phone and email:
"At 1023 CDT, on 10/29/2024, with Unit 2 in Mode 1 at 100 percent [reactor] power, during the performance of surveillance procedure 2047, CONTROL ROD QUARTERLY EXERCISE, Unit 2 experienced an automatic reactor trip [followed by a] turbine trip. All control rods fully inserted into the core following the reactor trip. The cause of the Unit 2 reactor trip is being investigated.
"Operations responded and stabilized the plant. Auxiliary feedwater actuated as expected. Decay heat is being removed by the steam generators through the main steam dumps to the condenser. The Unit 2 reactor trip was not complex with all systems responding normally post trip.
"Due to the actuation of the reactor protection system (RPS) of Unit 2, this event is being reported as a RPS Actuation in accordance with the reporting criteria of 10 CFR 50.72(b)(2)(iv)(B).
"Due to the actuation of the auxiliary feedwater system following the Unit 2 reactor trip, this event is being reported as a specified system actuation in accordance with the reporting criteria of 10 CFR 50.72(b)(3)(iv)(A).
"There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified."
The following information was provided by the licensee via phone and email:
"At 1023 CDT, on 10/29/2024, with Unit 2 in Mode 1 at 100 percent [reactor] power, during the performance of surveillance procedure 2047, CONTROL ROD QUARTERLY EXERCISE, Unit 2 experienced an automatic reactor trip [followed by a] turbine trip. All control rods fully inserted into the core following the reactor trip. The cause of the Unit 2 reactor trip is being investigated.
"Operations responded and stabilized the plant. Auxiliary feedwater actuated as expected. Decay heat is being removed by the steam generators through the main steam dumps to the condenser. The Unit 2 reactor trip was not complex with all systems responding normally post trip.
"Due to the actuation of the reactor protection system (RPS) of Unit 2, this event is being reported as a RPS Actuation in accordance with the reporting criteria of 10 CFR 50.72(b)(2)(iv)(B).
"Due to the actuation of the auxiliary feedwater system following the Unit 2 reactor trip, this event is being reported as a specified system actuation in accordance with the reporting criteria of 10 CFR 50.72(b)(3)(iv)(A).
"There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified."
Power Reactor
Event Number: 57406
Facility: Perry
Region: 3 State: OH
Unit: [1] [] []
RX Type: [1] GE-6
NRC Notified By: Darin Smith
HQ OPS Officer: Ernest West
Region: 3 State: OH
Unit: [1] [] []
RX Type: [1] GE-6
NRC Notified By: Darin Smith
HQ OPS Officer: Ernest West
Notification Date: 10/29/2024
Notification Time: 17:32 [ET]
Event Date: 10/29/2024
Event Time: 11:52 [EDT]
Last Update Date: 10/29/2024
Notification Time: 17:32 [ET]
Event Date: 10/29/2024
Event Time: 11:52 [EDT]
Last Update Date: 10/29/2024
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(3)(v)(D) - Accident Mitigation
10 CFR Section:
50.72(b)(3)(v)(D) - Accident Mitigation
Person (Organization):
Edwards, Rhex (R3DO)
Edwards, Rhex (R3DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
INOPERABILITY OF DIVISION 3 DIESEL GENERATOR SUPPORTING HIGH PRESSURE CORE SPRAY
The following information was provided by the licensee via phone and email:
"At 1152 EDT, on 10/29/2024, the division 3 diesel generator was declared inoperable due to variations in steady state voltage during a planned monthly surveillance run. Troubleshooting of the issue is in progress. This condition could prevent the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). All other emergency core cooling systems were operable during this time.
"There was no impact on the health and safety of the public or plant personnel. The NRC resident inspector has been notified."
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
Limiting condition for operations (LCO) 3.8.1.b was entered as a result of this event.
The following information was provided by the licensee via phone and email:
"At 1152 EDT, on 10/29/2024, the division 3 diesel generator was declared inoperable due to variations in steady state voltage during a planned monthly surveillance run. Troubleshooting of the issue is in progress. This condition could prevent the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). All other emergency core cooling systems were operable during this time.
"There was no impact on the health and safety of the public or plant personnel. The NRC resident inspector has been notified."
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
Limiting condition for operations (LCO) 3.8.1.b was entered as a result of this event.
Power Reactor
Event Number: 57407
Facility: Perry
Region: 3 State: OH
Unit: [1] [] []
RX Type: [1] GE-6
NRC Notified By: Robert Heil
HQ OPS Officer: Rodney Clagg
Region: 3 State: OH
Unit: [1] [] []
RX Type: [1] GE-6
NRC Notified By: Robert Heil
HQ OPS Officer: Rodney Clagg
Notification Date: 10/29/2024
Notification Time: 18:07 [ET]
Event Date: 10/29/2024
Event Time: 17:30 [EDT]
Last Update Date: 10/29/2024
Notification Time: 18:07 [ET]
Event Date: 10/29/2024
Event Time: 17:30 [EDT]
Last Update Date: 10/29/2024
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(2)(xi) - Offsite Notification
10 CFR Section:
50.72(b)(2)(xi) - Offsite Notification
Person (Organization):
Edwards, Rhex (R3DO)
Edwards, Rhex (R3DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
OFFSITE NOTIFICATION
The following information was provided by the licensee via phone and email:
"At 1730 [EDT], on 10/29/2024, Vistra authorized a report to the State of Ohio in accordance with NEI 07-07, 'Industry Groundwater Protection Initiative,' of a liquid spill to the plant's outdoor ground from an outdoor cask holding radioactive waste. This spill contained radionuclides cobalt-60 and manganese-54 with activities greater than the site procedural limits for state reporting. The outdoor cask has been removed from the onsite storage area; remediation and causal investigation activities are being performed. This exceedance did not exceed any NRC regulations or reporting criteria. There was no impact on the health and safety of the public or plant personnel.
"This notification is being made solely as a four-hour, non-emergency notification for a Notification of Other Government Agency. This event is reportable in accordance with 10 CFR 50.72(b)(2)(xi).
"The NRC Resident Inspector has been notified."
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
No EPA limits were exceeded
The following information was provided by the licensee via phone and email:
"At 1730 [EDT], on 10/29/2024, Vistra authorized a report to the State of Ohio in accordance with NEI 07-07, 'Industry Groundwater Protection Initiative,' of a liquid spill to the plant's outdoor ground from an outdoor cask holding radioactive waste. This spill contained radionuclides cobalt-60 and manganese-54 with activities greater than the site procedural limits for state reporting. The outdoor cask has been removed from the onsite storage area; remediation and causal investigation activities are being performed. This exceedance did not exceed any NRC regulations or reporting criteria. There was no impact on the health and safety of the public or plant personnel.
"This notification is being made solely as a four-hour, non-emergency notification for a Notification of Other Government Agency. This event is reportable in accordance with 10 CFR 50.72(b)(2)(xi).
"The NRC Resident Inspector has been notified."
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
No EPA limits were exceeded
Part 21
Event Number: 57483
Rep Org: Ametek Solidstate Controls
Licensee:
Region: 3
City: Columbus State: OH
County:
License #:
Agreement: Y
Docket:
NRC Notified By: Zachary Rumora
HQ OPS Officer: Bill Nytko
Licensee:
Region: 3
City: Columbus State: OH
County:
License #:
Agreement: Y
Docket:
NRC Notified By: Zachary Rumora
HQ OPS Officer: Bill Nytko
Notification Date: 12/28/2024
Notification Time: 11:01 [ET]
Event Date: 10/29/2024
Event Time: 00:00 [EST]
Last Update Date: 08/20/2025
Notification Time: 11:01 [ET]
Event Date: 10/29/2024
Event Time: 00:00 [EST]
Last Update Date: 08/20/2025
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):
Elkhiamy, Sarah (R1DO)
Franke, Mark (R2DO)
Part 21/50.55 Reactors, - (EMAIL)
Elkhiamy, Sarah (R1DO)
Franke, Mark (R2DO)
Part 21/50.55 Reactors, - (EMAIL)
EN Revision Imported Date: 8/21/2025
EN Revision Text: PART 21 - INTERIM REPORT FOR REGULATING TRANSFORMER
The following is a synopsis of information provided by AMETEK Solidstate Controls Inc. (AMETEK) via email:
During regulating transformer system operations, the transformer may be experiencing short circuiting between coils to ground.
Visual inspection for severe darkening or charring of coils, magnetic shunts, or core, and/or the use of thermal probes or infrared guns monitoring for excessive temperatures greater than 180 degrees Celsius or 355 degrees Fahrenheit may detect affected regulating transformer systems.
Affected systems exhibit signs of transformer insulation system deterioration, increased audible noise from the units, blackening on any areas of the transformer, or signs of electrical shorting between windings or coil to core.
The cause of the short circuiting is unknown. Component failure impact analysis and regulating transformer system electrical testing are in progress.
Recommend all units currently in service with internal components, which include but are not limited to capacitors, wire harnesses, and transformer materials, with temperatures in excess of 180 degrees Celsius or 355 degrees Fahrenheit be removed from service.
COMPONENT DESCRIPTION:
The AMETEK SCI model numbers listed are for regulating transformers that are intended to take in AC power at 460 VAC plus or minus 10 percent and output AC power at 120 VAC plus or minus 2 percent with low harmonic distortion.
Models: 85-IS0075-12 and 85-IS0150-14
AFFECTED PLANTS:
Southern Nuclear Company - Vogtle
Constellation Energy - Ginna
* * * UPDATE ON 03/11/25 AT 1530 EDT FROM ZACHARY RUMORA TO KERBY SCALES * * *
The following is a synopsis of the information provided from Ametek:
Test were performed on both models (85-IS0075-14 and 85-IS0075-12).
Model 85-IS0075-12 was found to be functioning as expected during testing and did not present a failure mode. Therefore, Ginna is not affected by this component.
Regarding model 85-IS0075-14, dielectric testing was performed and the apparent source of the failure was a short-circuit between the secondary coil of the transformer and the magnetic shunts and center leg of the transformer core. The suspected cause of this short circuit is the design of the magnetic shunt. Various actions are being reviewed to enhance model 85-IS0150-14 specifically regarding the insulation system of the transformer around the coils and magnetic shunts. An updated report is expected to be completed in May/June.
Notified R1DO (Schussler), R2DO (Pearson), Part 21 Group (email)
* * * UPDATE ON 08/20/2025 AT 0748 EDT FROM ZACHARY RUMORA TO ROBERT THOMPSON * * *
The following is a synopsis of the information provided from Ametek:
AMETEK is submitting the final report on the potential defect. A design change is being implemented to enhance the insulation system of the transformer used in model 85-IS0150-14. This design change is expected to be released by August 31, 2025. Additionally, an alternative regulating transformer design is available that can replace the existing design.
AFFECTED PLANTS:
Southern Nuclear Company - Vogtle
Notified R1DO (Dimitriadis), R2DO (Bacon), Part 21 Group (email)
EN Revision Text: PART 21 - INTERIM REPORT FOR REGULATING TRANSFORMER
The following is a synopsis of information provided by AMETEK Solidstate Controls Inc. (AMETEK) via email:
During regulating transformer system operations, the transformer may be experiencing short circuiting between coils to ground.
Visual inspection for severe darkening or charring of coils, magnetic shunts, or core, and/or the use of thermal probes or infrared guns monitoring for excessive temperatures greater than 180 degrees Celsius or 355 degrees Fahrenheit may detect affected regulating transformer systems.
Affected systems exhibit signs of transformer insulation system deterioration, increased audible noise from the units, blackening on any areas of the transformer, or signs of electrical shorting between windings or coil to core.
The cause of the short circuiting is unknown. Component failure impact analysis and regulating transformer system electrical testing are in progress.
Recommend all units currently in service with internal components, which include but are not limited to capacitors, wire harnesses, and transformer materials, with temperatures in excess of 180 degrees Celsius or 355 degrees Fahrenheit be removed from service.
COMPONENT DESCRIPTION:
The AMETEK SCI model numbers listed are for regulating transformers that are intended to take in AC power at 460 VAC plus or minus 10 percent and output AC power at 120 VAC plus or minus 2 percent with low harmonic distortion.
Models: 85-IS0075-12 and 85-IS0150-14
AFFECTED PLANTS:
Southern Nuclear Company - Vogtle
Constellation Energy - Ginna
* * * UPDATE ON 03/11/25 AT 1530 EDT FROM ZACHARY RUMORA TO KERBY SCALES * * *
The following is a synopsis of the information provided from Ametek:
Test were performed on both models (85-IS0075-14 and 85-IS0075-12).
Model 85-IS0075-12 was found to be functioning as expected during testing and did not present a failure mode. Therefore, Ginna is not affected by this component.
Regarding model 85-IS0075-14, dielectric testing was performed and the apparent source of the failure was a short-circuit between the secondary coil of the transformer and the magnetic shunts and center leg of the transformer core. The suspected cause of this short circuit is the design of the magnetic shunt. Various actions are being reviewed to enhance model 85-IS0150-14 specifically regarding the insulation system of the transformer around the coils and magnetic shunts. An updated report is expected to be completed in May/June.
Notified R1DO (Schussler), R2DO (Pearson), Part 21 Group (email)
* * * UPDATE ON 08/20/2025 AT 0748 EDT FROM ZACHARY RUMORA TO ROBERT THOMPSON * * *
The following is a synopsis of the information provided from Ametek:
AMETEK is submitting the final report on the potential defect. A design change is being implemented to enhance the insulation system of the transformer used in model 85-IS0150-14. This design change is expected to be released by August 31, 2025. Additionally, an alternative regulating transformer design is available that can replace the existing design.
AFFECTED PLANTS:
Southern Nuclear Company - Vogtle
Notified R1DO (Dimitriadis), R2DO (Bacon), Part 21 Group (email)