ENS 47942
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ENS Event | |
|---|---|
07:49 May 22, 2012 | |
| Title | Automatic Scram Due to Reactor Protection System Being De-Energized |
| Event Description | At 0249 CDT on 5/22/2012, Unit 3 reactor automatically scrammed due to de-energization of Reactor Protection System (RPS) from actuation of 3A Unit Station Service Transformer (USST) differential relay 387SA, which resulted in a loss of 500KV power to Unit 3. This relay was picked up during a transfer of 4KV Unit Board 3C from alternate power (161KV) to normal power (3A USST). Investigation is in progress as to the cause of relay actuation. 500KV power was restored through the alternate feeder breakers from 161KV to all Unit 3 4KV Unit Boards successfully. 161KV remained available during the entire event. Loss of 500KV power lasted less than 30 seconds and power has been restored to all safety related boards. All Unit 3 diesel generators successfully started and tied to their respective 4KV Shutdown Boards.
All safety systems responded as expected to the loss of 500KV power. No Emergency Core Cooling System (ECCS) or Reactor Core Isolation Cooling (RCIC) reactor water level initiation set points were reached. RCIC was manually started to control reactor water level. Primary Containment Isolation System (PCIS) and PCIS initiation signals for groups 1, 2, 3, 6 & 8 were received as designed. At the time of the scram, High Pressure Coolant Injection (HPCI) system was tagged out for removal of temporary instrumentation following planned maintenance. This event is reportable within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> per 10CFR 50.72(b)(2)(iv)(B) 'any event or condition that results in actuation of the reactor protection system (RPS) when the reactor is critical except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation'. It is also reportable within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> per 10CFR 50.72(b)(3)(iv)(A) and requires an LER within 60 days per 10CFR 50.73(a)(2)(iv)(A). The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Browns Ferry  Alabama (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:+-0.18 h-0.0075 days <br />-0.00107 weeks <br />-2.46564e-4 months <br />) | |
| Opened: | Todd Christensen 07:38 May 22, 2012 |
| NRC Officer: | John Knoke |
| Last Updated: | May 22, 2012 |
| 47942 - NRC Website | |
Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (19 %) |
| After | Hot Shutdown (0 %) |
Browns Ferry with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 569902024-02-24T08:19:00024 February 2024 08:19:00
[Table view]10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Start of Emergency Diesel Generator ENS 565312023-05-20T08:15:00020 May 2023 08:15:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram ENS 547952020-07-21T09:35:00021 July 2020 09:35:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Biofouling of Intake Structure Leads to Manual Reactor Scram of Unit 1 ENS 547942020-07-20T18:25:00020 July 2020 18:25:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Biofouling of Intake Structure Leads to Manual Reactor Scram of Unit 2 and Downpower of Units 1 & 3 ENS 545592020-03-03T10:16:0003 March 2020 10:16:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Generator Actuation ENS 543022019-10-01T08:07:0001 October 2019 08:07:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram During Reactor Startup ENS 539232019-03-10T04:59:00010 March 2019 04:59:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Scram Resulting in Rps and Eccs Actuation ENS 532692018-03-18T16:58:00018 March 2018 16:58:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Turbine Control Valve Closure ENS 531622018-01-10T15:28:00010 January 2018 15:28:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Turbine Control Valve Fast Closure Scram Signal ENS 526482017-03-29T23:44:00029 March 2017 23:44:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Scram Initiated During Startup ENS 518782016-04-22T18:59:00022 April 2016 18:59:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Partial Loss of Power Experienced During Electrical Bus Transfer ENS 513332015-08-20T15:32:00020 August 2015 15:32:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Start of an Emergency Diesel Generator on Low Bus Voltage ENS 504042014-08-26T22:30:00026 August 2014 22:30:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Generator Neutral Overvoltage Causes a Reactor Scram ENS 500902014-05-06T13:30:0006 May 2014 13:30:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Low Reactor Water Level During Instrument Testing ENS 499282014-03-19T03:52:00019 March 2014 03:52:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Due to Failure to Control Main Turbine Moisture Separator Level ENS 488292013-03-19T09:02:00019 March 2013 09:02:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Lowering Condenser Vacuum ENS 487822013-02-25T19:13:00025 February 2013 19:13:00 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 Automatic Scram Due to a Turbine Trip from a Loss of Condenser Vacuum ENS 489042013-02-11T11:13:00011 February 2013 11:13:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Initiation of Reactor Core Isolation Cooling System ENS 486232012-12-22T17:52:00022 December 2012 17:52:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Loss of Power to the Reactor Protection System ENS 479722012-05-29T08:31:00029 May 2012 08:31:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Main Generator Load Reject Signal ENS 479552012-05-24T11:39:00024 May 2012 11:39:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram During Startup ENS 479422012-05-22T07:49:00022 May 2012 07:49:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Scram Due to Reactor Protection System Being De-Energized ENS 472992011-09-28T09:14:00028 September 2011 09:14:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to a Turbine Trip ENS 471302011-08-06T11:17:0006 August 2011 11:17:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Initiation of Technical Specification Required Shutdown ENS 468722011-05-22T22:37:00022 May 2011 22:37:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Reactor Protection System (Rps) Actuation Signal - Scram Discharge Volume (Sdv) High Water Level ENS 468052011-05-02T11:26:0002 May 2011 11:26:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation Due to a Emergency Diesel Generator Output Breaker Trip ENS 468012011-04-29T04:38:00029 April 2011 04:38:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Primary Containment Isolation System Actuation Due to Loss of Power from a Diesel Generator ENS 467932011-04-27T22:01:00027 April 2011 22:01:00 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)(xiii), Loss of Emergency Preparedness Notification of Unusual Event Due to Loss of Offsite Power ENS 465112010-12-26T22:20:00026 December 2010 22:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to High Vibration on Main Generator Exciter ENS 459902010-06-09T08:31:0009 June 2010 08:31:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Due to Closure of Main Steam Isolation Valves ENS 458882010-04-30T21:48:00030 April 2010 21:48:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Light Socket Short Causes Isolation Systems to Actuate ENS 453912009-09-30T04:23:00030 September 2009 04:23:00 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 Unit 2 Manually Scrammed After Trip of an Operating Condensate Pump and Rapidly Lowering Rvwl ENS 452902009-08-24T23:50:00024 August 2009 23:50:00 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 Condensate Booster Pump Trip Resulting in a Manual Reactor Scram ENS 448602009-02-18T09:51:00018 February 2009 09:51:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Trip Due to Power Load Unbalance Signal on Main Generator Resulting in Reactor Scram ENS 448542009-02-16T11:13:00016 February 2009 11:13:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Loss of Stator Cooling Water ENS 445402008-10-05T03:08:0005 October 2008 03:08:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Following Reverse Power Signal on Main Generator ENS 441872008-05-05T08:32:0005 May 2008 08:32:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Power to Esf Buses During Transfer of Offsite Power Source ENS 438782008-01-01T03:40:0001 January 2008 03:40:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 3 Automatic Scram Due to Main Generator Load Reject Signal ENS 437182007-10-12T13:02:00012 October 2007 13:02:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Turbine Trip ENS 436132007-09-03T07:14:0003 September 2007 07:14:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Electro-Hydraulic Control (Ehc) System Leak ENS 435602007-08-11T22:51:00011 August 2007 22:51:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Scram Due to Neutron Monitoring Trip Signal ENS 434142007-06-09T16:00:0009 June 2007 16:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due Turbine Trip as a Result of High Moisture Separator Reheater Tank Level ENS 433812007-05-24T07:11:00024 May 2007 07:11:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Electro-Hydraulic Control (Ehc) System Leak ENS 431592007-02-09T18:08:0009 February 2007 18:08:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Reactor Scram Due to Low Reactor Water Level ENS 430922007-01-11T14:16:00011 January 2007 14:16:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram When Turbine Output Breakers Opened ENS 428132006-08-30T03:25:00030 August 2006 03:25:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Electro-Hydraulic Oil Leak ENS 427872006-08-19T16:05:00019 August 2006 16:05:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram of Unit 3 Due to the Loss of Both Reactor Recirculation Pumps ENS 421022005-10-31T19:18:00031 October 2005 19:18:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Trip of Main Turbine ENS 419972005-09-17T16:29:00017 September 2005 16:29:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Due to Maintenance ENS 418962005-08-05T22:08:0005 August 2005 22:08:00 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 Rps Actuation Due to Low Reactor Water Level Caused by Loss of Reactor Feed Pumps ENS 415952005-04-13T15:53:00013 April 2005 15:53:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Rps Actuation Due to an Invalid Atws Logic Actuation ENS 414042005-02-11T22:29:00011 February 2005 22:29:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to a Load Rejection ENS 412192004-11-23T16:02:00023 November 2004 16:02:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Turbine Trip ENS 408622004-07-11T03:35:00011 July 2004 03:35:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to an Upscale Trip on Intermediate Range Monitors ENS 408582004-07-09T03:32:0009 July 2004 03:32:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Due to a Turbine Generator Load Rejection Signal 2024-02-24T08:19:00 | |
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