ENS 57773
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ENS Event | |
|---|---|
18:38 Jun 21, 2025 | |
| Title | Unusual Event - Unit 4 Containment Isolation Failure Due to Bus Lockout |
| Event Description | The following information is a summary of the information provided by the licensee via phone and email:
On 6/21/2025, at 1438 EDT, Turkey Point experienced an unplanned reactor trip and a spurious safety injection signal when the '4A' 4 kV bus locked out. An Unusual Event, SU8.1, was declared at 1453 EDT due to two open, motor-operated steam generator sample containment isolation valves not closing on the phase 'A' containment isolation signal due to the loss of power. There were no abnormal parameters that would require a safety injection signal. Turkey Point unit 3 was unaffected and remains at 100 percent power. Turkey Point unit 4 is stable in mode 3. The state and one county were notified, and the other county will be notified. The NRC Resident Inspector was notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The licensee manually closed the valves due to loss of power to the bus, and they are investigating the cause of the reactor trip.
Turkey Point unit 4 exited the Unusual Event at 1609 EDT. Notified R2RA (Lara), NRR (Bowman), NSIR (Erlanger), R2DO (Blamey), NRR EO (Felts), IR MOC (Whited), R2 PAO (Gasperson). Notified DHS SWO, FEMA Operations Center, CISA Central Watch Officer, FEMA NWC, DHS Nuclear SSA (email), CWMD Watch Desk (email).
The following information was provided by the licensee via phone and email: On June 21, 2025, at 1438 EDT, while Turkey Point Unit 4 was in mode 1 at 100 percent power, the reactor automatically tripped due to lockout of the '4A' 4 kV bus. The cause of the bus lockout is unknown. The trip was complicated with all systems responding normally post-trip, except for containment isolation valves powered from the '4A' 4 kV bus. Operations stabilized the plant in mode 3. Decay heat is removed by discharging steam from the steam generators to atmosphere. Unit 3 is not affected. This event is being reported pursuant to 10 CFR 50.72(b)(2)(iv)(B). An actuation of the auxiliary feedwater (AFW) system occurred during the reactor trip and safety injection signal. The AFW pumps automatically started as designed when the low steam generator, safety injection, and '4A' 4 kV bus undervoltage signals were received. This event is being reported pursuant to 10 CFR 50.72(b)(3)(iv)(A). The NRC Resident Inspector has been notified." Notified R2DO (Blamey). |
| Where | |
|---|---|
Turkey Point  Florida (NRC Region 2) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-3.13 h-0.13 days <br />-0.0186 weeks <br />-0.00429 months <br />) | |
| Opened: | Chad Hellman 15:30 Jun 21, 2025 |
| NRC Officer: | Karen Cotton |
| Last Updated: | Jun 21, 2025 |
| 57773 - NRC Website
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Turkey Point with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 578572025-08-09T15:13:0009 August 2025 15:13:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip ENS 577732025-06-21T18:38:00021 June 2025 18:38:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event - Unit 4 Containment Isolation Failure Due to Bus Lockout ENS 576032025-03-13T23:02:00013 March 2025 23:02:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event - Loss of Offsite Power ENS 576042025-03-13T22:47:00013 March 2025 22:47:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Actuation of '4B' Emergency Diesel Generator ENS 574532024-12-04T15:33:0004 December 2024 15:33:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip ENS 568132023-10-25T01:59:00025 October 2023 01:59:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip ENS 567552023-09-22T22:19:00022 September 2023 22:19:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip ENS 566582023-08-04T17:20:0004 August 2023 17:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip ENS 562642022-12-08T19:02:0008 December 2022 19:02:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Due to Excessive Reactor Coolant System Leakage ENS 555132021-10-09T07:00:0009 October 2021 07:00:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Auxiliary Feedwater System AUTO-STARTED on Feedwater Isolation Signal ENS 551532021-03-25T01:29:00025 March 2021 01:29:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notice of Unusual Event Declared Due to Fire Alarm in Containment ENS 551172021-03-01T16:12:0001 March 2021 16:12:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip Due to Reactor Protection System Actuation ENS 548472020-08-21T03:54:00021 August 2020 03:54:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Steam Generator Water Level Control ENS 548442020-08-19T17:25:00019 August 2020 17:25:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip During Startup ENS 548392020-08-18T01:13:00018 August 2020 01:13:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Rising Steam Generator Level ENS 547622020-07-06T01:09:0006 July 2020 01:09:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Trip Due to Turbine Trip ENS 540722019-05-18T15:08:00018 May 2019 15:08:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Due Grid Disturbance ENS 529602017-09-10T22:55:00010 September 2017 22:55:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip on Lowering Steam Generator Water Level ENS 529522017-09-08T03:14:0008 September 2017 03:14:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event - Hurricane Warning ENS 526212017-03-18T15:19:00018 March 2017 15:19:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Alert Declared for Indications of Fire in Safety Related Switchgear ENS 526232017-03-18T15:07:00018 March 2017 15:07:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Reactor Trip and Loss of Ability for Unit 4 to Supply Power to Unit 3 ENS 521362016-07-30T07:33:00030 July 2016 07:33:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Turkey Point Unit 3 Shutdown Due to Water Hammer ENS 510652015-05-12T08:30:00012 May 2015 08:30:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip Due to Main Generator Differential Trip ENS 506452014-11-30T18:54:00030 November 2014 18:54:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Auxiliary Feedwater Actuation Due to Planned Reactor Trip ENS 503542014-08-11T14:20:00011 August 2014 14:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip on Loss of Instrument Air Followed by Safety Injection ENS 501402014-05-25T09:36:00025 May 2014 09:36:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip Due to Turbine Trip on Loss of Condenser Vacuum ENS 500542014-04-23T17:02:00023 April 2014 17:02:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation During Rod Testing ENS 490212013-05-10T15:08:00010 May 2013 15:08:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Unit 3 Manual Reactor Trip Due to Malfunction of Turbine Valves ENS 489482013-04-19T21:20:00019 April 2013 21:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Due to Loss of Offsite Power Greater than 15 Minutes ENS 488212013-03-13T15:20:00013 March 2013 15:20:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Afw Actuation Due to Trip of 3B Feedwater Pump ENS 488172013-03-12T18:31:00012 March 2013 18:31:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip Due to Turbine Inlet Pressure Perturbation ENS 487642013-02-18T06:31:00018 February 2013 06:31:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Due to High Seal Leakoff on Reactor Coolant Pump 3A ENS 487442013-02-12T03:36:00012 February 2013 03:36:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to Turbine Trip on Loss of Condenser Vacuum ENS 477972012-04-02T23:33:0002 April 2012 23:33:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event - Fire from Hydrogen Supply to Volume Control Tank ENS 466602011-03-06T21:44:0006 March 2011 21:44:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Secondary Sodium Concentrations Exceeding Chemistry Limits ENS 464712010-12-10T03:58:00010 December 2010 03:58:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip After Indications of a Condenser Tube Leak ENS 464192010-11-15T11:03:00015 November 2010 11:03:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Due to Loss of a Circulating Water Pump with Another Pump Out of Service for Maintenance ENS 462742010-09-23T21:14:00023 September 2010 21:14:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip Due to Inadvertent Energization Generator Trip ENS 462652010-09-22T00:17:00022 September 2010 00:17:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip ENS 462462010-09-09T19:34:0009 September 2010 19:34:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip During Startup Due to a Control Bank Step Counter Failure ENS 462352010-09-08T17:45:0008 September 2010 17:45:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip During Maintenance on a Reactor Protection System Relay ENS 456192010-01-11T15:55:00011 January 2010 15:55:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Initiated Due to High Steam Generator Level ENS 455222009-11-27T04:40:00027 November 2009 04:40:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Two Shutdown Bank Rods Were Dropped from Fully Withdrawn Position ENS 440162008-02-29T09:51:00029 February 2008 09:51:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to High Steam Generator Water Level ENS 440092008-02-26T18:09:00026 February 2008 18:09:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Units 3 and 4 Tripped Due to Grid Fluctuations ENS 423992006-03-08T20:53:0008 March 2006 20:53:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Actuation of Emergency Diesel Generators ENS 421372005-11-11T20:02:00011 November 2005 20:02:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip During Startup Following Failure of Rod Control Power Cabinet ENS 421042005-11-01T03:27:0001 November 2005 03:27:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Declaration: Loss of Offsite Power Due to Loss of Startup Transformer ENS 420782005-10-26T01:40:00026 October 2005 01:40:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to a Small Fire at the Main Turbine Area ENS 420672005-10-23T02:54:00023 October 2005 02:54:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Hurricane Wilma ENS 420562005-10-15T11:02:00015 October 2005 11:02:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Auxiliary Feedwater Actuation on a Manual Reactor Trip ENS 420012005-09-19T15:04:00019 September 2005 15:04:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Hurricane Rita ENS 419432005-08-25T03:04:00025 August 2005 03:04:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Hurricane Warning ENS 418002005-06-27T07:16:00027 June 2005 07:16:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Declaration of an Unusual Event Due Transformer Fire >10 Minutes ENS 417432005-06-03T04:33:0003 June 2005 04:33:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Declared Unusual Event Due to Rcs Leakage in Excess of Technical Specification Limit ENS 415162005-03-24T00:56:00024 March 2005 00:56:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Manually Tripped from 20% Power During Load Reduction. ENS 415112005-03-22T08:47:00022 March 2005 08:47:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Manually Tripped Following Loss of Main Feed Pump ENS 412982004-12-29T03:46:00029 December 2004 03:46:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Due to Generator Exciter Cooling Water Leak ENS 412922004-12-25T12:36:00025 December 2004 12:36:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Unit4 Manually Tripped Due to Lowering Condenser Vacuum ENS 412572004-12-14T16:45:00014 December 2004 16:45:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Manually Tripped Due to Fire on Unit 3 Hp Turbine ENS 412322004-11-30T13:50:00030 November 2004 13:50:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Dropped Control Rod ENS 412292004-11-29T05:09:00029 November 2004 05:09:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specifications Required Shutdown Due to Dropped Control Rod ENS 410682004-09-24T21:00:00024 September 2004 21:00:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Hurricane Warning ENS 410072004-09-02T14:56:0002 September 2004 14:56:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event Declared ENS 407522004-05-14T21:29:00014 May 2004 21:29:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Scram Due to Lowering Steam Generator Level 2025-08-09T15:13:00 | |
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