ENS 42157
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ENS Event | |
|---|---|
23:51 Nov 19, 2005 | |
| Title | Unplanned Diesel Generator Starts on a Vaild Bus Undervoltage Signal |
| Event Description | On November 19, 2005 at 1551 Pacific Standard Time Diablo Canyon Unit 2 [was] in Mode 1 (Power Operation) at approximately 100% power when the 230kv offsite power supply breaker (#212) opened. Diesel generators 2-1, 2-2, and 2-3 auto-started on a valid bus undervoltage signal.
The immediate cause of the event was the opening of the 230kv breaker (#212) due to a valid (but unintentional) startup transformer 1-1 sudden pressure switch activation due to maintenance being performed on the Unit 1 Startup Transformer 1-1. All equipment performed as expected. None of the diesel generators picked up load since the buses remained energized. The safety buses were powered by offsite power. Unit 1 is in a refueling outage and was not adversely affected. The diesel generators are currently being returned to a standby condition. The licensee will notify the NRC Resident Inspector. |
| Where | |
|---|---|
Diablo Canyon  California (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| LER: | 05000323/LER-2005-002 |
| Time - Person (Reporting Time:+-3.5 h-0.146 days <br />-0.0208 weeks <br />-0.00479 months <br />) | |
| Opened: | James M. Welsch 20:21 Nov 19, 2005 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Nov 19, 2005 |
| 42157 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 567692023-10-01T03:14:0001 October 2023 03:14:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip ENS 555262021-10-16T00:49:00016 October 2021 00:49:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip and Automatic Auxiliary Feedwater Actuation ENS 537642018-12-01T08:00:0001 December 2018 08:00:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip of Unit 2 Due to a Load Rejection ENS 519652016-05-30T16:30:00030 May 2016 16:30:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Opening of Reactor Trip Breakers Due to Rod Position Error Greater than 12 Steps ENS 505862014-11-01T00:40:0001 November 2014 00:40:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Emergency Diesel Generator Start Due to Loss of Offsite 230Kv Startup Power Supply ENS 497862014-02-02T19:29:0002 February 2014 19:29:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 2 Automatic Reactor Trip ENS 492872013-08-16T01:24:00016 August 2013 01:24:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Startup Power Results in Valid Starts of All Three Emergency Diesel Generators ENS 491842013-07-10T16:50:00010 July 2013 16:50:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 2 Automatic Reactor Trip ENS 491432013-06-24T04:20:00024 June 2013 04:20:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of 230 Kv Offsite Power Results in the Automatic Start of Emergency Diesel Generators ENS 487962013-03-01T05:54:0001 March 2013 05:54:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Bus Inadvertently De-Energized with Unit Defueled ENS 484002012-10-11T19:08:00011 October 2012 19:08:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 2 Experienced an Automatic Reactor Trip on a 500Kv Line Differential Relay Actuation ENS 469002011-05-27T19:12:00027 May 2011 19:12:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Unit 1 Startup Power Results in Starting All Emergency Diesel Generators ENS 468942011-05-26T09:26:00026 May 2011 09:26:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Startup Power Due to Fault in Switchyard Causes All Edgs to Start ENS 468562011-05-17T16:54:00017 May 2011 16:54:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Generators Start Due to Maintenance Activities ENS 467012011-03-26T21:49:00026 March 2011 21:49:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip When a Loss of the 2-1 Main Feedwater Pump Occurred ENS 445882008-10-22T03:51:00022 October 2008 03:51:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 2 Manual Reactor Trip Due to Jellyfish Intrusion ENS 444192008-08-17T07:12:00017 August 2008 07:12:00 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 Fire in Main Bank Tranformer ENS 433932007-05-29T05:50:00029 May 2007 05:50:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Generator Actuation Due to Momentary Undervoltage Condition ENS 433912007-05-27T18:17:00027 May 2007 18:17:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip in Mode 3 During Control Rod Testing ENS 433602007-05-12T17:25:00012 May 2007 17:25:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Generators Start Due to Loss of Off Site Start Up Power ENS 430472006-12-12T21:22:00012 December 2006 21:22:00 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 Circulating Water Pump Failure Causes Explosion in Intake Structure ENS 430422006-12-11T00:08:00011 December 2006 00:08:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Rapid Shutdown and Manual Reactor Trip Due to High Reactor Coolant Pump Stator Temperature ENS 421572005-11-19T23:51:00019 November 2005 23:51:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unplanned Diesel Generator Starts on a Vaild Bus Undervoltage Signal ENS 412502004-12-09T10:04:0009 December 2004 10:04:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Rps Actuation While Shutdown Due to Failed Fuse ENS 411682004-11-02T19:05:0002 November 2004 19:05:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unplanned Diesel Generator Start on a Valid Bus Undervoltage Signal 2023-10-01T03:14:00 | |
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