ENS Event | |
|---|---|
07:14 May 22, 2015 | |
| Title | Emergency Diesel Generator Start Due to Actuation of Undervoltage Circuitry |
| Event Description | At 0014 PDT on 05/22/2015, Columbia experienced an unexpected momentary loss of SM-7, a Division 1 4.16 kV vital bus, resulting in a start of Emergency Diesel DG-1 . Additionally, under voltage circuitry prevented Standby Service Water pump 1A from starting to support DG-1 in response to the valid under voltage condition, and operators tripped the diesel at 0016 PDT. The SM-7 bus was reenergized by a 115 kV offsite source through backup transformer TR-B.
The cause of this event was an inadvertent trip of under voltage circuitry while connecting test equipment in preparation for Diesel and Loss of Power logic testing. Division 1 was inoperable due to ongoing maintenance during the current refueling outage and was not being relied upon for decay heat removal or core circulation. Columbia is in Mode 5 with a coolant temperature of 96 degrees F, water level is at the normal refueling flooded level with fuel pool cooling gates removed. Division 2 is providing required electrical power and supporting components required for decay heat removal and inventory control. There was no impact to Shutdown Safety Assessment. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Columbia  Washington (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+3.48 h0.145 days <br />0.0207 weeks <br />0.00477 months <br />) | |
| Opened: | Mot Hedges 10:43 May 22, 2015 |
| NRC Officer: | Daniel Mills |
| Last Updated: | May 22, 2015 |
| 51086 - NRC Website
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WEEKMONTHYEARENS 559382022-06-13T16:23:00013 June 2022 16:23:00
[Table view]10 CFR 50.72(b)(3)(iv)(A), System Actuation Partial Loss of Power to RPS During Maintenance ENS 529182017-08-20T23:05:00020 August 2017 23:05:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to a Rise in Main Condenser Back Pressure ENS 524422016-12-18T19:24:00018 December 2016 19:24:00 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 Automatic Scram Due to Load Reject from Substation ENS 510862015-05-22T07:14:00022 May 2015 07:14:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Generator Start Due to Actuation of Undervoltage Circuitry ENS 491202013-06-15T19:22:00015 June 2013 19:22:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Division 1 and 2 Emergency Diesel Generators Power Buses After Momentary Offsite Power Loss ENS 452452009-08-05T14:50:0005 August 2009 14:50:00 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 Toxic Gas from a Switchgear Fire in the Turbine Building ENS 417902005-06-23T20:46:00023 June 2005 20:46:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit Experienced an Automatic Reactor Scram Due to a Loss of Feedwater Flow ENS 417792005-06-15T21:00:00015 June 2005 21:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Turbine Throttle Valve Closure 2022-06-13T16:23:00 | |