ENS 49618
ENS Event | |
|---|---|
14:00 Dec 9, 2013 | |
| Title | Unusual Event Declared Due to Unit 2 Auxiliary Transformer Explosion |
| Event Description | At approximately 0748 [CST] on 12/9/2013, an electrical fault occurred resulting in a fire and explosion on the ANO [Arkansas Nuclear One] Unit 2 Unit Auxiliary Transformer. This caused a unit trip and a loss of power to Startup 3 Transformer, which is one of the two offsite power feeds to ANO Unit 2. ANO Unit 2 is currently in a stable shutdown condition. With Startup 3 and Unit Aux Transformer unavailable, power was lost to the Reactor Coolant Pumps and Circulating Water Pumps. RCS [Reactor Coolant System] natural circulation is in progress removing core decay heat. Emergency Feedwater actuated due to low steam generator levels and is supplying both steam generators. The unit is steaming to the atmosphere. 2A-1 and 2A-3 are powered from SU [Startup] 2 Transformer. 2A-4 is powered from 2K-4B Emergency Diesel Generator.
ANO Unit 1 is currently operating at 98% power. The auto transformer tripped off line with the fault in ANO Unit 2 Unit Auxiliary Transformer. This has caused Startup Transformer 1 to be inoperable. This places ANO Unit 1 in a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Technical Specification action statement (T.S 3.6.1 for Loss of the SU-1 Transformer). No significant injuries were reported as a result of this condition and offsite agencies have been notified. At 0800 on 12/9/2013 Unit 2 declared a Notification of Unusual Event based on EAL HU4 Fire or Explosion inside Protected Area not extinguished in 15 minutes. At 0917 on 12/9/2013, the fire on Unit 2 Unit Auxiliary Transformer is OUT. The Licensee notified the NRC Resident Inspector. Notified DHS SWO, DOE Ops Center, FEMA Ops Center, HHS Ops Center, NICC Watch Officer, USDA Ops Center, EPA EOC, and Nuclear SSA vial email.
At 1215 CST, ANO terminated from the Unusual Event as per HU4 stable plant conditions. ANO Unit 2 is stable and will be cooled down to Mode 5 via natural circulation and decay heat is being removed via emergency feedwater and downstream dump valves to atmosphere. There is no radiological release and no personnel injuries. The licensee has notified the NRC Resident Inspector, Arkansas Department of Emergency Management, Arkansas Department of Health, and other local authorities. Notified R4DO (Vasquez), NRR EO (King) and IRC MOC (Morris). Notified DHS SWO, DOE Ops Center, FEMA Ops Center, HHS Ops Center, NICC Watch Officer, USDA Ops Center, EPA EOC, and Nuclear SSA vial email.
Outside agencies (National Response Center, Arkansas Department of Emergency Management, Corps of Engineers, and U.S. Coast Guard) were contacted due to a minor unknown amount of oil that entered the plant discharge to Lake Dardanelle. The oil was from the faulted Unit 2 Unit Auxiliary Transformer. The majority of oil was contained within the containment around the transformer or the oily water separator it drains to. Local inspection revealed only a small amount of what was released actually passed the containment booms that are continuously in place on the discharge canal. The oil boom was verified to be in good condition. The oil was verified to be mineral oil. The release was verified to be terminated. An additional oil boom was deployed. Reference [ANO] Condition Report CR-ANO-C-2013-03071. The licensee notified the NRC Resident Inspector. Notified the R4DO (Werner) |
| Where | |
|---|---|
Arkansas Nuclear  Arkansas (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)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-4.67 h-0.195 days <br />-0.0278 weeks <br />-0.0064 months <br />) | |
| Opened: | Dan Breedlove 09:20 Dec 9, 2013 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | Dec 9, 2013 |
| 49618 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
Arkansas Nuclear 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(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 563512023-02-14T17:03:00014 February 2023 17:03:00
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Notification of Onsite Chemical Spill ENS 516072015-12-15T11:44:00015 December 2015 11:44:00 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 Manual Reactor Trip Due to Loss of Feed to One Steam Generator ENS 507392015-01-15T21:45:00015 January 2015 21:45:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Hospitalized Injured Employee ENS 501382014-05-24T15:09:00024 May 2014 15:09:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Individual Requiring Assistance from Offsite Emergency Personnel ENS 500632014-04-28T01:12:00028 April 2014 01:12:00 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 an Auxiliary Trip on Core Protection Calculator ENS 499952014-04-03T18:01:0003 April 2014 18:01:00 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 496182013-12-09T14:00:0009 December 2013 14:00:00 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(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Declared Due to Unit 2 Auxiliary Transformer Explosion ENS 488692013-03-31T15:33:00031 March 2013 15:33:00 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(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Notification of Unusual Event Declared Due to a Breaker Explosion in the Protected Area ENS 481692012-08-08T13:23:0008 August 2012 13:23:00 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 High Reactor Coolant System Pressurizer Pressure ENS 478242012-04-11T17:40:00011 April 2012 17:40:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Drill Message Inadvertently Mistaken for Actual Event ENS 465552011-01-20T02:58:00020 January 2011 02:58:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notice of Unusual Event Due to a Security Event ENS 458722010-04-26T05:00:00026 April 2010 05:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Unit 1 Experienced an Automatic Reactor Trip During an Ni Calibration ENS 458542010-04-18T18:57:00018 April 2010 18:57:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip During Reactor Startup ENS 455492009-12-08T14:42:0008 December 2009 14:42:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Due to Low Steam Generator Level Caused by Loss of Main Feed Water Pump ENS 453672009-09-20T10:11:00020 September 2009 10:11:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unplanned Emergency Diesel Auto Start During Surveillance Testing ENS 449062009-03-14T02:51:00014 March 2009 02:51:00 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 Feedwater Regulating Valve Failure Leads to Manual Reactor Trip ENS 448372009-02-07T16:59:0007 February 2009 16:59:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to a Fire Onsite ENS 448312009-02-05T21:24:0005 February 2009 21:24:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Unit 1 Manually Tripped Due to Control Rod Drive Motor High Temperatures ENS 447362008-12-20T18:12:00020 December 2008 18:12:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip When Control Rod Bank Inserted Without Operator Action ENS 447162008-12-12T14:55:00012 December 2008 14:55:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Unit 1 Was Manually Tripped from 32% Power Due to an Abnormal Rod Pattern ENS 441252008-04-07T18:45:0007 April 2008 18:45:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Core Element Assembly Calculators Declared Inoperable ENS 437422007-10-24T04:05:00024 October 2007 04:05:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Alert Declared Due to Electrical Fire in the Auxiliary Building ENS 429492006-10-30T19:04:00030 October 2006 19:04:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Alert Declaration Due to Electrical Fire Affecting One Esf Train ENS 422292005-12-26T16:47:00026 December 2005 16:47:00 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 419072005-08-10T13:15:00010 August 2005 13:15:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Spurious Activation of Off-Site Emergency Plan Sirens ENS 414752005-03-09T19:04:0009 March 2005 19:04:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Investigation of Inadvertent Siren Activation ENS 410562004-09-19T14:34:00019 September 2004 14:34:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Siren Activation ENS 402042003-09-28T05:13:00028 September 2003 05:13:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Report of Emergency Siren Actuation ENS 401192003-08-29T19:28:00029 August 2003 19:28:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip on High Rcs Pressure 2023-02-14T17:03:00 | |