ENS 53491
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ENS Event | |
|---|---|
05:00 Jul 6, 2018 | |
| Title | Transformer Failure Causes Loss of Offsite Power to Unit 2 |
| Event Description | At 1201 [CDT], Station Auxiliary Transformer 242-2 experienced a bushing failure, resulting in a loss of offsite power to Unit 2. The 2A and 2B Diesel Generators started and sequenced loads onto the Unit 2 ESF buses appropriately. All other buses normally powered from the Station Auxiliary Transformers automatically transferred to the Unit Auxiliary Transformers. ESF Bus 241 and 242 Undervoltage Relays actuated to start the Diesel Generators and the 2A Auxiliary Feedwater Pump started on the 2A Diesel Generator sequencer. ESF Battery Charger 212 tripped at the same time, which was an unexpected condition. DC Bus 212 was cross-tied with DC Bus 112.
This notification is being made under 10 CFR 50.72(b)3(iv)(A) due to the actuation of both Unit 2 Diesel Generators and the 2A Auxiliary Feedwater Pump. The NRC Senior Resident Inspector has been notified. Currently, offsite power was restored via the Unit 1 Unit Auxiliary Transformer. Both Unit 2 Emergency Diesel Generators have been secured. DC Busses are still cross-tied. The licensee is currently in a 72-hour shutdown action statement for the loss of offsite power and a 7-day action statement for having the Unit 2 DC Bus cross-tied to Unit 1. |
| Where | |
|---|---|
Byron  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+10.6 h0.442 days <br />0.0631 weeks <br />0.0145 months <br />) | |
| Opened: | Mace Davis 15:36 Jul 6, 2018 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Jul 6, 2018 |
| 53491 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 540202019-04-22T18:24:00022 April 2019 18:24:00
[Table view]10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Initiation of the Auxiliary Feedwater System in Response to a Loss of Feedwater ENS 534912018-07-06T05:00:0006 July 2018 05:00:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Transformer Failure Causes Loss of Offsite Power to Unit 2 ENS 522952016-10-12T18:38:00012 October 2016 18:38:00 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 Spurious Feedwater Isolation ENS 508592015-03-03T17:01:0003 March 2015 17:01:00 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 Main Power Transformer Bushing Short ENS 499192014-03-15T16:02:00015 March 2014 16:02:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Momentary Loss of Shutdown Cooling Due to a Loss of Offsite Power ENS 488382013-03-21T00:51:00021 March 2013 00:51:00 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 Generator Stator Cooling Water ENS 477082012-02-28T23:31:00028 February 2012 23:31:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 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 ENS 476442012-02-06T23:19:0006 February 2012 23:19:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Rps Actuation Due to Turbine Trip ENS 476242012-01-30T16:01:00030 January 2012 16:01:00 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, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Unusual Event Due to Loss of Offsite Power Greater than 15 Minutes ENS 458672010-04-19T10:03:00019 April 2010 10:03:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Rps and Afw Actuation Signals While Shutdown in Mode 4 ENS 420632005-10-19T05:57:00019 October 2005 05:57:00 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 Low 2 Steam Generator Water Level 2019-04-22T18:24:00 | |
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