ENS 57124
ENS Event | |
|---|---|
21:41 May 12, 2024 | |
| Title | Automatic Reactor Trip |
| Event Description | The following information was provided by the licensee via email and phone:
At 1641 CDT on May 12, 2024, with Unit 2 in Mode 1 at 15 percent power, the reactor automatically tripped due to a unit auxiliary transformer lockout. During the trip, all control rods fully inserted. The cause of the transformer lockout is currently unknown. Emergency diesel generator (EDG) 21 and 23 actuated and all three engineered safety feature (ESF) busses were energized. All equipment responded as expected except for steam generator power operated relief valve (PORV) 2C which failed to open when required in automatic, and the load center (LC) E2A output breaker which failed to close automatically but was closed manually. Steam generator PORV 2C did open when placed in manual, although it subsequently failed to full open and was then closed. Primary system temperature and pressure are currently being maintained at 567 degrees/2235 psig following start of reactor coolant pumps 2A and 2D. Due to the reactor protection system actuation (RPS) while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). This event is also being reported per 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in a valid actuation of the emergency diesel generators. There was no impact to 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: South Texas Project Unit 2 was in Mode 1 at 15 percent power due to performance of testing and analysis on the main turbine prior to the RPS actuation.
The following information was provided by the licensee via email and phone: South Texas Project is submitting the following correction to the event notification: The steam generator (SG) power operated relief valve (PORV) 2C did not fail to open automatically. System pressure during this event did not reach the automatic setpoint for the PORV (1225 psi), and there was no demand for it to open automatically. During the event, SG PORV 2C was taken to manual and it went full open when the up button was pushed slightly. It went closed when the down button was pressed to close it manually. In addition, the load center E2A output breaker initially failed to close automatically, however, after operations placed it in pull-to-lock and returned the hand switch to automatic, it closed automatically. Notified R4DO (Dixon). |
| Where | |
|---|---|
South Texas  Texas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| LER: | 05000499/LER-2024-001 Automatic Reactor Trip and Actuation of Two of Three Emergency Diesel Generators 05000499/LER-2024-001-01 Supplement to Automatic Reactor Trip and Actuation of Two of Three Emergency Diesel Generators |
| Time - Person (Reporting Time:+-0.92 h-0.0383 days <br />-0.00548 weeks <br />-0.00126 months <br />) | |
| Opened: | Ron Rohan 20:46 May 12, 2024 |
| NRC Officer: | Tenisha Meadows |
| Last Updated: | May 22, 2024 |
| 57124 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (15 %) |
| After | Hot Standby (0 %) |
South Texas with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 572372024-07-24T12:02:00024 July 2024 12:02:00
[Table view]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 Notification of Unusual Event Due to Loss of Offsite Power ENS 571242024-05-12T21:41:00012 May 2024 21:41:00 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 568772023-12-02T12:10:0002 December 2023 12:10:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation - Auto Start of Emergency Diesel Generator ENS 556922022-01-06T12:03:0006 January 2022 12:03:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation - Auto Start Emergency Diesel Generator ENS 551042021-02-15T11:26:00015 February 2021 11:26:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip Due to Low Steam Generator Level ENS 546052020-03-24T15:46:00024 March 2020 15:46:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation - Auto Start Emergency Diesel Generators ENS 543512019-10-25T01:51:00025 October 2019 01:51:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Undervoltage Actuation During Edg Sequencer Maintenance ENS 518972016-05-02T01:21:0002 May 2016 01:21:00 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 Generator Lockout ENS 516872016-01-27T05:25:00027 January 2016 05:25:00 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 Feedwater to a Single Steam Generator ENS 516152015-12-21T21:33:00021 December 2015 21:33:00 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 Feedwater Isolation ENS 496662013-12-20T04:33:00020 December 2013 04:33:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Actuation of Main Steam Isolation Valves That Was Not Part of a Preplanned Sequence ENS 486592013-01-08T22:40:0008 January 2013 22:40:00 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 Declared Due to Main Transformer Fire ENS 486512013-01-04T15:41:0004 January 2013 15:41:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 2 Manually Tripped After Two Shutdown Control Rods Unexpectedly Dropped During Surveillance Testing ENS 474852011-11-29T09:29:00029 November 2011 09:29:00 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 Generator Lockout ENS 463872010-11-03T15:21:0003 November 2010 15:21:00 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 Unusual Event Declared Due to an Explosion in the Protected Area Which Affects Normal Operations ENS 462982010-10-01T00:04:0001 October 2010 00:04:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Standby Diesel Generator Autostart Due to Loss of a Switchyard Bus During Maintenance ENS 461912010-08-20T20:25:00020 August 2010 20:25:00 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 an Inadvertent Turbine Trip Signal During Testing ENS 446052008-10-26T04:42:00026 October 2008 04:42:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Safety Injection Signal Due to Maintenance Error ENS 404732004-01-23T22:16:00023 January 2004 22:16:00 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 High-High Steam Generator Level 2024-07-24T12:02:00 | |