ENS 43047
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ENS Event | |
|---|---|
21:22 Dec 12, 2006 | |
| Title | Circulating Water Pump Failure Causes Explosion in Intake Structure |
| Event Description | On December 12, 2006, at 1322 PST, while conducting power ascension operations with Unit 2 at approximately 25 percent power, an electrical failure occurred in the Unit 2 circulating water pump motor enclosure (CWP) 2-1. A loud bang and explosion was reported to the Unit 2 control room. At 1322 PST, an electrical transient was experienced on Unit 2 12-Kv non-vital bus 'D' which in turn caused reactor coolant pump (RCP) 2-2 and RCP 2-4 motor breakers to trip on 12kV non-vital bus 'D' undervoltage, initiating an automatic reactor trip. The reactor trip signal was initiated when 2 out of 4 RCP motor breakers opened. All control rods fully inserted in response to the reactor trip and all plant systems functioned as required. The auxiliary feedwater system for Unit 2 was manually actuated per plant procedures, before an auto-start signal for this system was generated. At 1356 PST, DCPP Fire Department first responders reported that the fire was out.
At 1340 the licensee declared a Notice of Unusual Event (NUE), number 23, 'Confirmed Explosion Onsite'. Decay heat is being removed via auxiliary feedwater to the steam generators steaming to the atmospheric dump valves. Emergency power is being supplied via offsite power. The NRC resident inspector has been informed and was onsite at the time of the Unit 2 reactor trip. Diablo Canyon Power Plant [DCPP] Unit 2 is presently in Mode 3. There were no injuries associated with this event. Investigations into the electrical transient are ongoing. DCPP Unit 2 will remain in Mode 3 pending the results of this investigation. An estimated restart of DCPP Unit 2 is not known at this time. DCPP Unit 1 is unaffected and remains in Mode 1 at 100% power.
The licensee terminated the Unusual Event at 1430 PST. The Notice of Unusual Event was terminated due to the fact the licensee assessed the damage to the circulating water pump and determined that the explosion was caused by a breaker in the local area. The licensee fire brigade was satisfied that the fire was extinguished and that the damage was confined to the local area of circulating water pump 2-1. The licensee notified the NRC Resident Inspector. Notified the R4DO (Smith), NRR EO (Highland), IRD (Wilson), DHS (Inzer), and FEMA (Discoe).
The licensee provided an update to make the formal 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> notification pursuant to 10 CFR 50.72 (b)(2)(iv)(B) due to the RPS actuation while critical, and the formal 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> notification pursuant to 10 CFR 50.72 (b)(3)(iv)(A) due to the actuation of the auxiliary feedwater system. The licensee notified the NRC Resident Inspector. Notified the R4DO (Smith), and NRR EO (Highland). |
| Where | |
|---|---|
Diablo Canyon  California (NRC Region 4) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| LER: | 05000323/LER-2006-004 |
| Time - Person (Reporting Time:+-4.38 h-0.183 days <br />-0.0261 weeks <br />-0.006 months <br />) | |
| Opened: | Tony Chitwood 16:59 Dec 12, 2006 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Dec 12, 2006 |
| 43047 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (23 %) |
| After | Hot Standby (0 %) |
Diablo Canyon with 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 | |
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 528762017-07-28T19:06:00028 July 2017 19:06:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Alert Declared Due to Low Oxygen Levels Inside Containment 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 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 484272012-10-21T07:09:00021 October 2012 07:09:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Seismic Event 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 466682011-03-11T09:23:00011 March 2011 09:23:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notice of Unusual Event as a Result of a Tsunami Warning in the Area ENS 465092010-12-26T00:25:00026 December 2010 00:25:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event Declared Due to High Winds 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 459922010-06-09T18:12:0009 June 2010 18:12:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Toxic Gas/Chemical Spill in the Protected Area ENS 451122009-06-02T08:22:0002 June 2009 08:22:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event - Smoke Alarm in Protected Area Lasting Greater than 15 Minutes 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 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 417742005-06-15T03:50:00015 June 2005 03:50:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event Due to Tsunami Warning 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 410762004-09-28T17:30:00028 September 2004 17:30:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Seismic Activity ENS 404082003-12-22T19:22:00022 December 2003 19:22:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event - Earthquake ENS 402582003-10-18T07:52:00018 October 2003 07:52:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Earthquake Felt on Site. Entered Emergency Action Level (Eal) 18 2023-10-01T03:14:00 | |
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