ENS 45556
ENS Event | |
|---|---|
19:23 Dec 9, 2009 | |
| Title | Automatic Reactor Trip on Unit 2 and Edg Start on Both Units Due to Inadvertent Loss of "C" Reserve Station Service Transformer |
| Event Description | At 1423 hours0.0165 days <br />0.395 hours <br />0.00235 weeks <br />5.414515e-4 months <br /> on 12/9/2009, electrical supply breaker L102 was inadvertently opened which caused electrical Bus 3 and the 'C' Reserve Station Service Transformer to de-energize. This caused the loss of 'F' Transfer Bus which resulted in a loss of power to the 1H and 2J Emergency Busses and an automatic start of the 1H and the 2J Emergency Diesel Generators. Both emergency diesel generators started and re-energized their associated emergency bus as designed.
The Unit 2 'G' Bus, which supplies power to the Unit 2 Circulating Water Pumps, did not automatically transfer to the 'B' Reserve Station Service Transformer in a sufficiently short time to prevent the loss of the Unit 2 Circulating Water pumps. The loss of the Unit 2 Circulating Water pumps resulted in an automatic low vacuum turbine trip and a subsequent [Unit 2] reactor trip due to the turbine trip. The 2 'G' Bus did automatically transfer to the 'B' Reserve Station Service Transformer and is currently energized. The Unit 2 Auxiliary Feedwater pumps automatically started and provided flow to the steam generators. There were no issues with the Auxiliary Feedwater System operation. The Unit 2 'A' Charging Pump and the Unit 2 'A' Component Cooling Water pump automatically started as designed due to the loss of power. The Unit 1 'B' Charging Pump and the Unit 1 'B' Component Cooling Water pump automatically started as designed due to the loss of power. The Unit 2 'C' Station Service Bus was lost following the trip when the electrical system automatically transferred to the Reserve Station Service transformers. With the 'C' Reserve Station Service Transformer de-energized the 'C' Station Service Bus was unable to transfer to an energized transformer. This resulted in the loss of the Unit 2 'C' Reactor Coolant Pump. The 'A' and 'B' Reactor Coolant Pumps remain in service at this time. The reactor trip is reportable per 10CFR50.72(b)(2)(iv)(B). The Auxiliary Feedwater system, Emergency Diesel Generator system, Charging system actuations are reportable per 10CFR50.72(b)(3)(iv)(A). The electrical system is being returned to a normal lineup. The condensate and feedwater system remained in service to provide flow to the steam generators. Steam Dump operation to the condenser is not available due to low condenser vacuum, therefore steam is being released to the atmosphere from the Steam Generator Power Operated Relief Valves. The licensee suspects that switchyard maintenance activities caused the L102 trip which initiated the chain of events. All rods inserted into the core during the trip. During the transient, some secondary relief valves lifted and properly reseated. There is no known primary to secondary leakage. During the event call, the licensee reported that the 'C' Reserve Station Service Transformer was returned to service. The licensee notified the NRC Resident Inspector and will be notifying the Louisa County Administrator. |
| Where | |
|---|---|
North Anna  Virginia (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-2.13 h-0.0888 days <br />-0.0127 weeks <br />-0.00292 months <br />) | |
| Opened: | Page Kemp 17:15 Dec 9, 2009 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Dec 9, 2009 |
| 45556 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (97 %) |
| After | Hot Standby (0 %) |
North Anna with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 571482024-05-29T10:24:00029 May 2024 10:24:00
[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 558432022-04-14T13:28:00014 April 2022 13:28:00 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 Control Rod Testing ENS 552392021-05-06T16:23:0006 May 2021 16:23:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip ENS 539082019-03-03T03:37:0003 March 2019 03:37:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Degrading Main Condenser Vacuum ENS 535792018-09-03T04:00:0003 September 2018 04:00:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Start of the Emergency Diesel Generator ENS 518922016-04-30T02:14:00030 April 2016 02:14:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Offsite Power to the a Reserve Station Service Transformer ENS 516782016-01-23T22:03:00023 January 2016 22:03:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Partial Loss of Power Results in Emergency Diesel Generators Starting ENS 509462015-04-02T08:26:0002 April 2015 08:26:00 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 Main Generator Voltage Regulator Failure ENS 508512015-02-26T20:11:00026 February 2015 20:11:00 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 Feedwater Regulating Valve Failing Closed ENS 501162014-05-15T23:20:00015 May 2014 23:20:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 1 and Unit 2 Emergency Diesel Generators Start and Load Due to Loss of One 34.5Kv Line ENS 497842014-02-02T13:59:0002 February 2014 13:59:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Following Loss of the "a" Main Feedwater Pump ENS 494292013-10-11T17:17:00011 October 2013 17:17:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Turbine and Reactor Trip Due to Station Service Transformer Lockout ENS 490752013-05-28T19:07:00028 May 2013 19:07:00 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 a Feedwater Transient ENS 490202013-05-10T10:12:00010 May 2013 10:12:00 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 Turbine Bearing Vibration ENS 484362012-10-24T05:47:00024 October 2012 05:47:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip on Low Steam Generator Water Level ENS 463522010-10-22T10:36:00022 October 2010 10:36:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip During Physics Testing Due to Problems with the Rod Control in Hold Out Switch ENS 460202010-06-16T23:20:00016 June 2010 23:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to a Lightning Storm ENS 459602010-05-28T04:03:00028 May 2010 04:03:00 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 Reactor Coolant Pump ENS 458772010-04-27T20:37:00027 April 2010 20:37:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip Following a Generator Lockout During Automatic Voltage Regulator Testing ENS 455562009-12-09T19:23:0009 December 2009 19:23:00 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 Unit 2 and Edg Start on Both Units Due to Inadvertent Loss of "C" Reserve Station Service Transformer ENS 450262009-04-28T13:53:00028 April 2009 13:53:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Auto-Start Due to Loss of the "B" Reserve Station Service Transformer ENS 439722008-02-08T23:12:0008 February 2008 23:12:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Control Rod Position Deviation ENS 438662007-12-26T02:10:00026 December 2007 02:10:00 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 Trip of "B" Reactor Coolant Pump ENS 434622007-06-29T21:52:00029 June 2007 21:52:00 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)(iv)(A), System Actuation - ECCS Discharge Reactor Trip and Spurious Safety Injection ENS 432172007-03-07T08:05:0007 March 2007 08:05:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Generator Autostart on Loss of "B" Reserve Station Service Transformer ENS 430722007-01-03T23:03:0003 January 2007 23:03:00 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 a Card Failure ENS 429962006-11-16T07:26:00016 November 2006 07:26:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip ENS 424832006-04-08T02:31:0008 April 2006 02:31:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Group Step Counter Failure During Reactor Startup ENS 418982005-08-06T02:28:0006 August 2005 02:28:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Apparently Due to Lightning Strike ENS 408042004-06-10T17:13:00010 June 2004 17:13:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip While Performing Scheduled Solid State Protection Testing ENS 407842004-05-29T06:02:00029 May 2004 06:02:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Control Rod Position Indication Failure During Hot Rod Drop Test 2024-05-29T10:24:00 | |