ENS 44860
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ENS Event | |
|---|---|
09:51 Feb 18, 2009 | |
| Title | Turbine Trip Due to Power Load Unbalance Signal on Main Generator Resulting in Reactor Scram |
| Event Description | At 0351 on 2/18/09, the Unit 1 reactor automatically scrammed due to actuation of the Reactor Protection System from a turbine trip due to a power load unbalance signal on the main generator. The cause of the power load unbalance signal was due to a generator neutral over voltage condition of which the cause is unknown and the investigation is continuing. All systems responded as expected to the turbine trip. One Safety Relief Valve (SRV) opened due to the reactor pressure transient, and then reactor pressure was automatically controlled by the Main Turbine Bypass valves. No Emergency Core Cooling System (ECCS), or Reactor Core Isolation Cooling (RCIC) reactor water level initiation set points were reached, all expected containment isolation and initiation signals were received, and reactor water level is being automatically controlled by the feedwater system.
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) for 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. All control rods fully inserted. The plant electrical system is in normal shut down alignment. No Diesel Generators started as a result of this event. There was no ECCS injection to the reactor vessel.
Review of available data indicates that no Main Steam safety/relief valves (MSRVs) opened in response to the Unit 1 reactor scram on 02/18/2009. There were no indications of an open MSRV on any discharge tailpipe thermocouple or acoustic monitor. Initial indications of the discharge tailpipe thermocouples for MSRV (1-PCV-1-30) did indicate a slight increase in temperature (approximately 36 degrees F) as reactor pressure decreased, which resulted in the initial assumption of an SRV opening. However, this behavior is a classical indication of slight main seat leakage and system engineering believes this seat leakage is what the post scram data indicates. Utilizing multiple reactor pressure instrumentation responses, the peak reactor pressure was determined to be approximately 1130 psig which is 15 psi below MSRV 1-PCV-1-30 setpoint. Additionally, the rise in tailpipe temperature did not coincide with the peak pressure but was after pressure had lowered. Based upon a thorough review of this data and a better understanding of the timing of the temperature rise, it is now believed that the MSRVs performed as designed during the reactor pressure transient event. The initial determination that concluded an MSRV opened will be further investigated within the corrective action program; reference PER 164114." The licensee has notified the NRC Resident Inspector. Notified R2 DO (Charlie Payne) |
| 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:+-1.8 h-0.075 days <br />-0.0107 weeks <br />-0.00247 months <br />) | |
| Opened: | Joe Bennett 08:03 Feb 18, 2009 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Feb 21, 2009 |
| 44860 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| 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
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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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