ENS 53132
ENS Event | |
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15:40 Dec 20, 2017 | |
Title | System Actuations Due to Opening of Feeder Breaker to Shutdown Board |
Event Description | On December 20, 2017, at 1040 Eastern Standard Time (EST), the Watts Bar Nuclear Plant (WBN) 1B-B 6.9kV Shutdown Board (SDBD) normal feeder breaker opened. The loss of voltage to the 1B-B SDBD resulted in the start of the 1B-B Motor Driven Auxiliary Feedwater (MDAFW) pump, the Unit 1 Turbine Driven Auxiliary Feedwater (TDAFW) pump, and the start of all four Emergency Diesel Generators (EDGs). Power was restored to the 1B-B 6.9 kV SDBD when it loaded on to its associated EDG.
Following initial investigation, the 1B-B 6.9 kV SDBD was transferred to its alternate offsite power source, Common Station Service Transformer (CSST) C at 1217 EST. At 1230 EST, the 1B-B 6.9 kV SDBD alternate feeder breaker opened. The loss of voltage to the 1B-B SDBD did not result in the restart of the 1B MDAFW pump, the Unit 1 TDAFW pump, or EDGs; this equipment remained running from the earlier event. Power was restored to the 1B-B 6.9 kV SDBD when it loaded on to its associated EDG. Restoration of normal offsite power to the 1B-B SDBD was completed at 1654. Other than several common Unit Technical Specifications having not been met, Unit 2 was not operationally impacted by the transfer of the 1B-B Shutdown Board to onsite power and remains in Mode 1 at 100% power. This report is made per 10 CFR 50.72(b)(3)(iv)(A). NRC Resident Inspector has been notified. The licensee investigation continues for the cause of the event. |
Where | |
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Watts Bar Tennessee (NRC Region 2) | |
Reporting | |
10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
Time - Person (Reporting Time:+2.63 h0.11 days <br />0.0157 weeks <br />0.0036 months <br />) | |
Opened: | Justin Gallagher 18:18 Dec 20, 2017 |
NRC Officer: | Vince Klco |
Last Updated: | Dec 20, 2017 |
53132 - NRC Website
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Unit 1 | |
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Reactor critical | Critical |
Scram | No |
Before | Power Operation (100 %) |
After | Power Operation (100 %) |
Unit 2 | |
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Reactor critical | Critical |
Scram | No |
Before | Power Operation (100 %) |
After | Power Operation (100 %) |
WEEKMONTHYEARENS 572142024-07-08T19:21:0008 July 2024 19:21:00
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Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Actuation of Turbine Driven Auxiliary Feedwater Pump Due to Loss of 6.9Kv Shutdown Board ENS 528722017-07-25T08:28:00025 July 2017 08:28:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Due to Rod Position Indication System Being Inoperable ENS 527322017-05-04T21:09:0004 May 2017 21:09:00 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 Failed Reactor Coolant Pump Power Transfer ENS 527252017-05-02T23:45:0002 May 2017 23:45:00 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 Failed Reactor Coolant Pump Power Transfer ENS 526302017-03-23T04:14:00023 March 2017 04:14:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Start of Auxiliary Feed Water ENS 526252017-03-20T12:13:00020 March 2017 12:13:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip as a Result of Secondary Plant Transient ENS 522102016-08-31T01:20:00031 August 2016 01:20:00 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 Notice of Unusual Event - Fire in a Main Bank Transformer ENS 521942016-08-23T17:56:00023 August 2016 17:56:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Trip Due to a Loss of Main Feedwater ENS 521772016-08-13T07:36:00013 August 2016 07:36:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Start of Turbine Driven Auxiliary Feed Water Pump ENS 520262016-06-20T19:40:00020 June 2016 19:40:00 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 519822016-06-05T16:27:0005 June 2016 16:27:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Reactor Trip and Eccs Actuation Caused by Turbine Governor Valve Failure ENS 519402016-05-17T20:30:00017 May 2016 20:30:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation - Loss of 1 B-B Electrical Buss ENS 518152016-03-22T15:31:00022 March 2016 15:31:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Watts Bar Automatic Reactor Trip ENS 508392015-02-21T15:32:00021 February 2015 15:32:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Inserted Due to Rapid Loss of Main Condenser Vacuum ENS 502782014-07-13T23:37:00013 July 2014 23:37:00 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 Automatic Feedwater Heater Isolation ENS 491542013-06-28T17:30:00028 June 2013 17:30:00 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 Offsite Electrical Fault ENS 484142012-10-17T03:30:00017 October 2012 03:30:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation All Four Emergency Diesel Generators Auto-Start on Valid Undervoltage Signal ENS 482382012-08-28T07:32:00028 August 2012 07:32:00 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 Failure of a Feedwater Regulating Valve ENS 469022011-05-29T05:55:00029 May 2011 05:55:00 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 Turbine Trip ENS 464182010-11-14T11:52:00014 November 2010 11:52:00 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 Loss of Cooling to the 'A' Phase Main Bank Transformer ENS 461772010-08-15T19:24:00015 August 2010 19:24:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Aux Feedwater System Actuation During Power Reduction for Turbine Maintenance ENS 459442010-05-21T23:37:00021 May 2010 23:37:00 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 Turbine Trip ENS 452102009-07-17T21:42:00017 July 2009 21:42:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Actuation of Emergency Diesel Generators Due to Loss of Power to Safety Related Bus ENS 445062008-09-20T13:06:00020 September 2008 13:06:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip Due to Turbine Trip ENS 443882008-08-07T06:28:0007 August 2008 06:28:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Trip from 50% Power Following Low Pressure Heater String Isolation ENS 427442006-07-31T16:13:00031 July 2006 16:13:00 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 Main Generator Trip ENS 426102006-05-30T21:00:00030 May 2006 21:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip on High Turbine Vibration ENS 410542004-09-19T08:56:00019 September 2004 08:56:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip in Response to Indication of Dropped Control Rods ENS 404542004-01-16T16:37:00016 January 2004 16:37:00 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 Turbine Trip ENS 401002003-08-25T13:45:00025 August 2003 13:45:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Turbine Trip/Reactor Trip Due to a Sudden Pressure Relay Signal from Main Transformer Bank "1C 2024-07-08T19:21:00 | |