ENS 48782
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ENS Event | |
|---|---|
19:13 Feb 25, 2013 | |
| Title | Automatic Scram Due to a Turbine Trip from a Loss of Condenser Vacuum |
| Event Description | At 1313 [CST] on 02/25/2013, the Unit 3 reactor automatically scrammed due to actuation of the Reactor Protection System from a turbine trip. Preliminary indications show the turbine tripped on low condenser vacuum. Cause of loss of condenser vacuum has been identified as Reactor Feedwater recirculation piping separation. Main Steam Isolation Valves (MSIVs) were manually closed to isolate the leak. None of the Safety Relief Valves (SRVs) automatically cycled during the transient, and one Safety Relief Valve (SRV) was manually operated to maintain Reactor Pressure due to the Main Turbine Bypass Valves unavailability because of loss of condenser vacuum. All systems responded as expected to the turbine trip. No Emergency Core Cooling System (ECCS) or Reactor Core Isolation Cooling (RCIC), reactor water level initiation set points were reached. Reactor water level is being controlled by the RCIC system and Reactor Pressure is being controlled with the High Pressure Coolant Injection (HPCI) system.
All expected containment isolation and initiation signals (Groups 2, 3, 6, and 8) were received. Upon receipt of these signals all required components actuated, with the exception of one valve in Group 6. Drywell Continuous Air Monitor (CAM) Inboard Return Isolation Valve 3-FSV-90-257 did not have indication following isolation signal and was not able to be verified locally. Indication was subsequently restored following restoration of containment isolation signals, and the Drywell CAM was manually isolated at 1422 [CST] with positive indication of isolation, and isolation valves deactivated at time 1514 [CST] to satisfy TS LCO 3.6.1.3 required actions. 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 10CFR50.72(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). At 1415 [CST], Suppression Pool Water level exceeded -1 inch due to operation with HPCI in pressure control mode, and required entry into TS LCO 3.6.2.2 condition A to restore level within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. Efforts are being made to lower suppression pool water level within limits. At 1615 [CST], water level remains above -1 inch requiring entry into TS LCO 3.6.2.2 condition B requiring action to be in MODE 3 in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. 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)(i), 'The initiation of any nuclear plant shutdown required by the plant's Technical Specifications.' The NRC Resident Inspector has been notified. All control rods fully inserted and electrical offsite power is in a normal shutdown configuration. Residual Heat Removal is aligned for suppression pool cooling. There was no impact on either Unit 1 or 2. |
| 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 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | |
| Time - Person (Reporting Time:+-1.4 h-0.0583 days <br />-0.00833 weeks <br />-0.00192 months <br />) | |
| Opened: | Neel Shukla 17:49 Feb 25, 2013 |
| NRC Officer: | Vince Klco |
| Last Updated: | Feb 25, 2013 |
| 48782 - NRC Website | |
Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (92 %) |
| 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, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | |
WEEKMONTHYEARENS 569902024-02-24T08:19:00024 February 2024 08:19:00
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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 467132011-03-30T20:42:00030 March 2011 20:42:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Initiated 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 457282010-02-26T01:35:00026 February 2010 01:35:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Rhr Inoperability 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 451242009-06-11T20:55:00011 June 2009 20:55:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Unit 2 Initiated a Tech Spec Required Shutdown Due to a Rise in Unidentified Drywell Leakage 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 418612005-07-22T08:16:00022 July 2005 08:16:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown T/S Shutdown Due to Dc Subsystem Declared Inoperable 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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