ENS 52710
ENS Event | |
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15:04 Apr 26, 2017 | |
Title | Unit 1 Automatic Reactor Scram Due to Partial Loss of Offsite Power |
Event Description | At 1004 CDT, Arkansas Nuclear One, Unit 1 (ANO-1) reactor automatically tripped due to the partial loss of offsite power. At the time of the trip, the site was in a Tornado Warning and a Severe Thunderstorm Warning. The Emergency Feedwater (EFW) system auto-actuated due to the loss of main feedwater pumps and the loss of the Reactor Coolant pumps. Both Emergency Diesel Generators started as expected with only one loading as expected. All control rods fully inserted. Currently, ANO-1 has stabilized in Hot Standby via natural circulation.
ANO-1 also lost Spent Fuel Pool cooling for approximately 69 minutes. The temperature of the spent fuel pool at the beginning of the event was approximately 102 [degrees] F. The spent fuel pool saw a heatup of 1 [degree] F during the loss of spent fuel pool cooling. The Spent Fuel Pool cooling has been restored. ANO-2 is currently in a refueling outage with all fuel in the spent fuel pool. ANO-2 completed a full core off load to the spent fuel pool and this was completed on April 12, 2017. Spent Fuel Pool cooling was lost for approximately 10 minutes. The Spent Fuel Pool temperature was 91 [degrees] F prior to the event. No heat up of the pool was identified during the event. Cooling has subsequently been restored. The #1 Emergency Diesel Generator auto-started as designed but did not supply the safety bus due to availability of offsite power. No radiological releases have occurred from either unit due to this event. The licensee has notified the NRC Resident Inspector. |
Where | |
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Arkansas Nuclear ![]() Arkansas (NRC Region 4) | |
Reporting | |
10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
LER: | 05000313/LER-2017-001 |
Time - Person (Reporting Time:+-0.25 h-0.0104 days <br />-0.00149 weeks <br />-3.4245e-4 months <br />) | |
Opened: | Josh Heathcock 14:49 Apr 26, 2017 |
NRC Officer: | Howie Crouch |
Last Updated: | Apr 26, 2017 |
52710 - NRC Website
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Unit 1 | |
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Reactor critical | Critical |
Scram | A/R |
Before | Power Operation (100 %) |
After | Hot Standby (0 %) |
Arkansas Nuclear ![]() | |
WEEKMONTHYEARENS 563512023-02-14T17:03:00014 February 2023 17:03:00
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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 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 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 | |