ENS 54605
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ENS Event | |
|---|---|
15:46 Mar 24, 2020 | |
| Title | Specified System Actuation - Auto Start Emergency Diesel Generators |
| Event Description | At 1046 CDT on 3/24/2020, with Unit 1 defueled and Unit 2 in Mode 1 at 100 percent power, the South Texas Project (STP) South switchyard electrical bus was deenergized. This resulted in a loss of power to Standby Transformer 2 which was supplying power to the Engineered Safety Features (ESF) 4160v busses for Unit 1 A- and C-Trains, and Unit 2 B-Train. Emergency Diesel Generators (EDGs) 11, 13, and 22 automatically started in response to the undervoltage condition.
The cause for the loss of the South switchyard electrical bus was an error in relay testing in the switchyard. This event is reportable under 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in the valid actuation of emergency AC electrical power systems (50.72(b)(3)(iv)(B)(8)) as well as the Unit 1 A- and C-Train and Unit 2 B-Train Reactor Containment Fan Coolers (50.72(b)(3)(iv)(B)(7)) and Unit 2 B-Train Auxiliary Feedwater pump (50.72(b)(3)(iv)(B)(6)). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
South Texas  Texas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+1.48 h0.0617 days <br />0.00881 weeks <br />0.00203 months <br />) | |
| Opened: | Michael Chandler 17:15 Mar 24, 2020 |
| NRC Officer: | Kerby Scales |
| Last Updated: | Mar 24, 2020 |
| 54605 - NRC Website | |
WEEKMONTHYEARENS 568772023-12-02T12:10:0002 December 2023 12:10:00
[Table view]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 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 2023-12-02T12:10:00 | |
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