ENS 50141
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ENS Event | |
|---|---|
11:02 May 25, 2014 | |
| Title | Unusual Event Due to Loss of Offsite Power |
| Event Description | At 0702 EDT on 5/25/14, Millstone Units 2 and 3 experienced a loss of offsite power and subsequent trip of both units. An Unusual Event was declared by Millstone Units 2 and 3 at 0715 EDT.
Power is currently being supplied to all emergency busses by the emergency diesel generators. Offsite power is not available. At this time, it appears that the loss of offsite power is due to a localized issue in the Millstone switchyard. The surrounding areas were not affected. A decision was made to take the NRC to monitoring mode at 0749 EDT with Region 1 in the lead. Notified DHS SWO, FEMA Ops Center, NICC Watch Officer, DOE Ops Center, USDA Ops Center, HHS Ops Center, and Nuclear SSA via email.
The loss of offsite power was due to one main line coming into the plant shorting to ground. Emergency plan procedures have been implemented, natural circulation has been established, and the plant is stable. Offsite electrical power has been restored to both Unit 2 and Unit 3. Emergency diesel generators have been secured, and plant equipment has been restored to a normal line up. Extended loss of instrument air following the loss of offsite power complicated the recovery actions. The normal reactor coolant system letdown flow path was not able to be established. This resulted in the rupture of the pressurizer relief tank rupture disk inside containment. The relief valve on the volume control tank lifted when restoring normal letdown. This caused the primary drains transfer tank to overflow into the auxiliary building. This overflow path has been isolated. Supplementary leakage collection system radiation monitor HVR-RE19B, and auxiliary building normal ventilation radiation monitor HVR-RE10B, are indicating normal levels. Notified R1DO (Gray), R1DRA (Lew), NRR EO (Kokajko), IRD MOC (Grant).
At 1414 EDT the licensee terminated the Unusual Event. Notified R1DO (Gray), R1DRA (Lew), NRR EO (Kokajko), IRD MOC (Grant), DHS SWO, FEMA Ops Center, NICC Watch Officer, DOE Ops Center, USDA Ops Center, HHS Ops Center, and Nuclear SSA via email. |
| Where | |
|---|---|
Millstone  Connecticut (NRC Region 1) | |
| 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 | |
| LER: | 05000336/LER-2014-006 |
| Time - Person (Reporting Time:+-3.53 h-0.147 days <br />-0.021 weeks <br />-0.00484 months <br />) | |
| Opened: | Michael Fortner 07:30 May 25, 2014 |
| NRC Officer: | Donald Norwood |
| Last Updated: | May 25, 2014 |
| 50141 - NRC Website | |
Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
Millstone 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 565442023-05-30T08:46:00030 May 2023 08:46:00
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Class Declaration Unusual Event Due to Fire Alarm in Containment ENS 521692016-08-11T13:59:00011 August 2016 13:59:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Loss of Two Circulating Water Pumps ENS 519292016-05-15T10:38:00015 May 2016 10:38:00 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 Due to Main Generator Hydrogen Leak in Turbine Building ENS 516822016-01-25T06:47:00025 January 2016 06:47:00 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 Reactor Coolant Pump Trip ENS 515212015-11-08T07:30:0008 November 2015 07:30:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Reactor Coolant Pump Oil Leak ENS 515132015-11-04T16:33:0004 November 2015 16:33:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Fire on the 'A' Emergency Diesel Generator ENS 514482015-10-04T13:32:0004 October 2015 13:32:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Identified Rcs Leakage > 25 Gpm ENS 501422014-05-25T11:02:00025 May 2014 11:02:00 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)(3)(xiii), Loss of Emergency Preparedness Unusual Event Due to Loss of Offsite Power ENS 501412014-05-25T11:02:00025 May 2014 11:02:00 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 Due to Loss of Offsite Power ENS 495252013-11-09T20:13:0009 November 2013 20:13:00 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 Loss of Condenser Vacuum ENS 492602013-08-10T01:19:00010 August 2013 01:19:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip on Low Steam Generator Water Level ENS 520002013-06-13T00:13:00013 June 2013 00:13:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 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 and Reactor Trip ENS 490392013-05-16T06:56:00016 May 2013 06:56:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip During Control Rod Testing ENS 474612011-11-20T22:58:00020 November 2011 22:58:00 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 Condenser Vacuum During Startup ENS 469712011-06-20T15:52:00020 June 2011 15:52:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 2 Reactor Trip Following the Loss of the "B" Main Feedwater (Mfw) Pump ENS 464412010-11-28T20:15:00028 November 2010 20:15:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip After Turbine Trip Due to Loss of Condenser Vacuum ENS 459452010-05-22T20:45:00022 May 2010 20:45:00 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 Steam Generator Water Level Control ENS 459312010-05-17T14:17:00017 May 2010 14:17:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to Low Steam Generator Water Level ENS 457292010-02-26T16:25:00026 February 2010 16:25:00 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 Two Circulating Water Pumps ENS 455832009-12-20T03:53:00020 December 2009 03:53:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Caused by a Turbine/Generator Electrical Fault ENS 454982009-11-15T13:26:00015 November 2009 13:26:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unit 2 Declared an Unusual Event Due to a Loss of Annunciators ENS 451832009-07-03T17:05:0003 July 2009 17:05:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Trip Resulting from Turbine Trip ENS 445642008-10-12T02:36:00012 October 2008 02:36:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Trip/ Automatic Reactor Trip on Low Steam Generator Level ENS 443262008-06-28T15:46:00028 June 2008 15:46:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Loss of Both Feedwater Pumps ENS 442382008-05-24T13:54:00024 May 2008 13:54:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Loss of Offsite Power ENS 442342008-05-22T18:20:00022 May 2008 18:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Trip Due to Lightning Strike ENS 441212008-04-06T17:17:0006 April 2008 17:17:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event from Reactor Coolant System Leakage ENS 433182007-04-25T15:01:00025 April 2007 15:01:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Loss of Offsite Power While Defueled ENS 427252006-07-25T13:45:00025 July 2006 13:45:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Trip Breakers Opened During Maintenance on Steam Generator Wide Level Channels ENS 423672006-02-23T15:22:00023 February 2006 15:22:00 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 Main Feedwater ENS 421802005-12-01T19:45:0001 December 2005 19:45:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to Low Steam Generator Level ENS 420242005-09-29T17:10:00029 September 2005 17:10:00 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 Circulating Water Pumps ENS 416072005-04-17T12:42:00017 April 2005 12:42:00 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)(iv)(A), System Actuation - ECCS Discharge Alert Declared Due to Unit 3 Main Steam Relief Valves Not Reseating After Actuation ENS 413332005-01-14T14:55:00014 January 2005 14:55:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Licensee Reported a Fire in the Turbine Building ENS 405912004-03-16T01:20:00016 March 2004 01:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip at Millstone 2 Due to Spurious Loss of One Main Feed Pump ENS 405702004-03-06T05:50:0006 March 2004 05:50:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip at Millstone 2 Due to Spurious Trip of the "B" Feed Pump ENS 403612003-11-29T03:05:00029 November 2003 03:05:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip from 11% Power Due to Turbine Vibration ENS 403582003-11-27T11:29:00027 November 2003 11:29:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Plant Had a Manual Reactor Trip from 23% Power Due to Turbine Vibration ENS 402452003-10-14T08:04:00014 October 2003 08:04:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared - Loss of Shutdown Cooling 2023-05-30T08:46:00 | |
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