ENS 48400
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ENS Event | |
|---|---|
19:08 Oct 11, 2012 | |
| Title | Unit 2 Experienced An Automatic Reactor Trip On A 500Kv Line Differential Relay Actuation |
| Event Description | On October 11, 2012, at 1208 PDT, the Diablo Canyon Power Plant Unit 2 500kV line differential relay actuated, resulting in a unit trip. The unit trip actuated the turbine trip. With the turbine tripped and Unit 2 operating above the P-9 50% power permissive, a reactor trip was initiated from the reactor protection system. All plant equipment responded as designed.
Unit 2 is stable at normal operating temperature and pressure. All power transferred to the plant startup source without incident. Condenser vacuum was maintained. The cause of the differential relay actuation is under investigation. Based on personnel observation it appears to have been initiated due to a flashover to ground across the phase 'A' main bank transformer capacitive coupled voltage transformer. PG&E will issue a press release regarding the Unit 2 trip. NRC Resident Inspectors have been informed of this event.
This update to clarify the status of the auxiliary feedwater system during the above noted transient. Both motor driven pumps and the steam driven pump automatically started as expected. In addition, on October 11, 2012, at 12:26 PDT, the Diablo Canyon Power Plant Unit 2 turbine driven auxiliary feedwater pump was secured by plant operators manually closing the steam supply valve to the pump turbine. This action was performed in accordance with plant operating procedures after the operators had verified that the indicated steam generator levels were greater than the procedural requirement of 16%. However, because the steam generator low level bistables associated with the auxiliary feedwater actuation circuits had not yet cleared, the emergency safeguards actuation signal drove the steam supply valve back open, restarting the turbine driven auxiliary feedwater pump. Operators increased steam generator levels to clear the bistables and successfully reclosed the steam supply valve. The NRC Resident Inspector has been informed of this event. Notified R4DO (Hagar). |
| Where | |
|---|---|
Diablo Canyon  California (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-0.4 h-0.0167 days <br />-0.00238 weeks <br />-5.4792e-4 months <br />) | |
| Opened: | Michael Quitter 18:44 Oct 11, 2012 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Oct 12, 2012 |
| 48400 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
Diablo Canyon with 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 | |
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 547892020-07-17T20:46:00017 July 2020 20:46:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Scram Due to Increased Hydrogen Usage 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 531842018-01-26T03:01:00026 January 2018 03:01:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Screen Wash Pump Motor Fire ENS 526522017-03-30T23:30:00030 March 2017 23:30:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Onsite Fatality 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 516552016-01-14T22:43:00014 January 2016 22:43:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event - Security Condition That Does Not Involve Hostile Action ENS 512462015-07-21T21:53:00021 July 2015 21:53:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Single Emergency Siren Inadvertent Actuation 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 503702014-08-14T23:31:00014 August 2014 23:31:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Unit 2 Technical Specification Required Shutdown Due to Multiple Inoperable Emergency Diesel Generators ENS 502352014-06-27T22:35:00027 June 2014 22:35:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to an Inadvertent Activation of an Emergency Siren 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 491482013-06-26T04:58:00026 June 2013 04:58:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Plant Shutdown Required Due to Rhr System Socket Weld Leak 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 478652012-04-26T05:27:00026 April 2012 05:27:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Press Release Issued for Shutdown of Unit 2 Due to Salp Influx ENS 477582012-03-21T14:49:00021 March 2012 14:49:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Inadvertent Offsite Notification During Simulator Training ENS 477332012-03-12T14:42:00012 March 2012 14:42:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification - Non-Work Related On-Site Fatality ENS 470792011-07-20T20:18:00020 July 2011 20:18:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification - Press Release After Fire on Site 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 462512010-09-14T15:15:00014 September 2010 15:15:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Minor Diesel Fuel Spill Into the Ocean ENS 460362010-06-23T17:48:00023 June 2010 17:48:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Alert Declared for a Cardox Discharge in the Turbine Building ENS 459942010-06-09T18:12:0009 June 2010 18:12:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Press Release Concerning a Caustic Spill ENS 452602009-08-13T20:04:00013 August 2009 20:04:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Potential Media Interest Due to Planned Maintenance Outage ENS 451782009-06-30T22:13:00030 June 2009 22:13:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Potential Media Interest Due to Forced Outage ENS 446752008-11-21T19:08:00021 November 2008 19:08:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification and Media Briefing Due to Potential Discovery of Offshore Fault Near Plant 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 443572008-07-21T16:08:00021 July 2008 16:08:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared - Unable to Validate a Fire Alarm within 15 Minutes ENS 442302008-05-21T22:00:00021 May 2008 22:00:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Mobile Crane Caused Damage to Met Tower 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 ENS 408362004-06-23T21:25:00023 June 2004 21:25:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification and Media Interest in Fire in Cafeteria 2023-10-01T03:14:00 | |
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