ENS 47022
ENS Event | |
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19:17 Jun 4, 2011 | |
Title | Invalid Specified System Actuation Caused All 4 Emergency Diesel Generators to Start |
Event Description | This report is a 60-day telephone notification in lieu of a written licensee event report being made under 10CFR50.73(a)(2)(iv)(A) and 10CFR50.73(a)(1). The event was an invalid actuation of all four Emergency Diesel Generators (EDGs). At the time of the event Unit 1 was at 100% power and Unit 2 was in a refueling outage with the core offloaded.
At 1517 EDT on 6/4/2011, breaker 212 on Vital Battery Board III was opened under a work order in preparation for breaker maintenance. The opening of this breaker started the 2A-A EDG by removing the control power to the 2A-A EDG emergency start relays. In addition, the loss of control power to 2A-A EDG remote control circuit actuated a relay in the common emergency start circuit, which caused the other three EDGs to start. The 2A-A EDG was declared inoperable until it's control power was restored approximately 30 minutes after starting, requiring an unplanned entry for Unit 1 into Technical Specification Limiting Condition for Operation 3.8.1.1 action b. The impact on EDG control power was not foreseen when planning the breaker maintenance, so it was not expected that any EDGs would start. Both trains of the Unit 1 and 2 EDGs received a complete train actuation, started and functioned successfully. The EDGs ran unloaded. Actual plant conditions did not exist that required an automatic start of the EDGs. Therefore, this actuation was invalid. The 4 EDGs were not loaded and were returned to normal stand-by alignment. The licensee notified the NRC Resident Inspector. |
Where | |
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Sequoyah Tennessee (NRC Region 2) | |
Reporting | |
10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
Time - Person (Reporting Time:+734.18 h30.591 days <br />4.37 weeks <br />1.006 months <br />) | |
Opened: | Richard Agnew 09:28 Jul 5, 2011 |
NRC Officer: | John Shoemaker |
Last Updated: | Jul 5, 2011 |
47022 - 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 %) |
WEEKMONTHYEARENS 551302021-01-11T16:52:00011 January 2021 16:52:00
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