ENS 46178
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ENS Event | |
|---|---|
07:06 Aug 16, 2010 | |
| Title | Automatic Reactor Trips at Both Units |
| Event Description | Braidwood Unit 2 automatically tripped at 0206 [CST] due to a turbine generator trip due to generator lockout relay actuation. All systems responded as expected, with the auxiliary feed water pumps starting on Low-2 Steam Generator level. The Unit is stable in Mode 3, all primary systems are stable with the secondary heat sink being maintained via aux feed water and the steam dumps. Offsite power is supplying Unit 2, and both emergency diesel generators are available. Cause of generator lockout is under investigation.
Braidwood Unit 1 automatically tripped at 0219 [CST] on a turbine trip caused by a loss of condenser vacuum. All systems responded as expected, with the auxiliary feed water pumps supplying steam generator levels. Secondary heat sink is steam generator PORVs. One steam generator safety valve is not fully seated. No steam generator tube leakage. Cause of the loss of vacuum is under investigation. For both Units all control rods fully inserted. There were no complications during the trip and all systems functioned as required. Offsite power remained available throughout the transient. The licensee notified the NRC resident inspector. Braidwood Unit 1's loss of condenser vacuum was caused by the loss of an electrical bus supplying the circ water pumps. At the time of this report, both plants were in a normal shutdown electrical lineup with the exception of the deenergized bus supplying power to the circ water pumps on Unit 1. The steam generator safety valve that has not fully seated was characterized as weeping a small amount of steam. The licensee is uncertain if the Unit 1 trip is related to the Unit 2 trip. |
| Where | |
|---|---|
Braidwood  Illinois (NRC Region 3) | |
| 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:+-0.72 h-0.03 days <br />-0.00429 weeks <br />-9.86256e-4 months <br />) | |
| Opened: | Walter Smith 06:23 Aug 16, 2010 |
| NRC Officer: | Dong Park |
| Last Updated: | Aug 16, 2010 |
| 46178 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
Braidwood with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 553202021-06-21T05:51:00021 June 2021 05:51:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Trip on Generator Lockout Relay Trip ENS 542892019-09-23T16:06:00023 September 2019 16:06:00 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 Lowering Steam Generator Levels ENS 534432018-06-04T14:20:0004 June 2018 14:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip on Lowering Steam Generator Water Level ENS 533712018-04-30T16:24:00030 April 2018 16:24:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Following Turbine Trip ENS 533582018-04-22T21:46:00022 April 2018 21:46:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Undervoltage Actuation of the Engineered Safety Feature Bus ENS 533472018-04-19T16:52:00019 April 2018 16:52:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Undervoltage Actuation of the Engineered Safety Feature Bus ENS 514502015-10-05T06:05:0005 October 2015 06:05:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuations ENS 462622010-09-20T22:04:00020 September 2010 22:04:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip ENS 461782010-08-16T07:06:00016 August 2010 07:06:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trips at Both Units ENS 452382009-07-31T02:08:00031 July 2009 02:08:00 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 Declared Due to a Loss of Offsite Power for Greater than 15 Minutes ENS 450172009-04-24T16:41:00024 April 2009 16:41:00 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 Instrument Calibration ENS 447432008-12-27T20:18:00027 December 2008 20:18:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip as a Result of a Generator Trip ENS 435902007-08-23T20:30:00023 August 2007 20:30:00 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)(3)(xiii), Loss of Emergency Preparedness Manual Reactor Trip Because of Lowering Condenser Vacuum ENS 434492007-06-27T14:21:00027 June 2007 14:21:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip Due to Off-Site Power Fluctuation ENS 415352005-03-28T18:46:00028 March 2005 18:46:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip Due to Generator Protection Circuitry ENS 412802004-12-22T19:07:00022 December 2004 19:07:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Rps Actuation Due to Steam Generator Low Level Signal ENS 403702003-12-03T09:36:0003 December 2003 09:36:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Plant Had an Auto Reactor Trip from 100% Power Due to Steam Generator Low Level ENS 402982003-11-05T03:32:0005 November 2003 03:32:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Braidwood 2 Afw Support System Actuation During Outage 2021-06-21T05:51:00 | |
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