ENS 41868
ENS Event | |
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04:00 Jul 25, 2005 | |
Title | Automatic Reactor Trip Caused By Failure In Switchyard |
Event Description | At 1525 the plant experienced a load reject generator trip due to a catastrophic failure in the 345 Kv switchyard. A reactor scram occurred as a result. The degraded AC power system prevented a fast transfer from occurring. Degraded bus voltage caused the emergency diesel generators (EDGs) to start. A residual bus transfer restored power to the 4 Kv busses. The [main steam isolation valves] (MSIVs) closed on a low-low reactor water level of 82.5 inches. [Reactor Core Isolation Cooling] and [High Pressure Coolant Injection] (HPCI) also started on the low-low reactor vessel water level.
The [Safety Relief Valves] were cycled twice for pressure control. OT 3100 Reactor Scram procedure was executed. EOP-3 was entered due to elevated torus water temperature and both loops of [Residual Heat Removal] (RHR) are in torus cooling. Water level has restored and is being maintained by feedwater. The MSIVs have been reopened and the scram reset. EDGs were secured. The plant is currently shutdown and stable with all control rods fully inserted. Decay heat removal is being accomplished with HPCI in pressure control mode. The licensee is transitioning to feeding with normal feedwater and steam exhausting through drains. Both trains of RHR are providing torus cooling. Electric power is being provided by offsite power. The licensee is currently investigating the event in the switchyard. The licensee notified the NRC Resident Inspector and will issue a press release.
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Where | |
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Vermont Yankee File:NorthStar Vermont Yankee icon.png Vermont (NRC Region 1) | |
Reporting | |
10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | |
LER: | 05000271/LER-2005-001 |
Time - Person (Reporting Time:+13.58 h0.566 days <br />0.0808 weeks <br />0.0186 months <br />) | |
Opened: | Andrew Wisniewski 17:35 Jul 25, 2005 |
NRC Officer: | Pete Snyder |
Last Updated: | Jul 29, 2005 |
41868 - NRC Website
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Unit 1 | |
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Reactor critical | Critical |
Scram | A/R |
Before | Power Operation (100 %) |
After | Hot Shutdown (0 %) |
Vermont YankeeFile:NorthStar Vermont Yankee icon.png 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(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge | |
WEEKMONTHYEARENS 527872017-06-03T10:15:0003 June 2017 10:15:00
[Table view]10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification of a Fatality ENS 475422011-12-21T20:15:00021 December 2011 20:15:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Water Sample Testing Positive for Low Level of Tritium ENS 473792011-10-26T15:25:00026 October 2011 15:25:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification to State and Local Officials Due to Inadvertent Siren Activation ENS 472002011-08-26T17:45:00026 August 2011 17:45:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Press Release Regarding Licensee Hurricane Preparation Activities ENS 459572010-05-26T19:26:00026 May 2010 19:26:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram While Increasing Power ENS 456132010-01-07T20:30:0007 January 2010 20:30:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification to State and Local Agencies Concerning Results of Quarterly Ground Water Analysis ENS 436102007-08-30T19:13:00030 August 2007 19:13:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram on Turbine Stop Valve Closure ENS 418682005-07-25T04:00:00025 July 2005 04:00:00 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(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Automatic Reactor Trip Caused by Failure in Switchyard ENS 417002005-05-15T05:18:00015 May 2005 05:18:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification of Onsite Fatality ENS 408672004-07-13T22:00:00013 July 2004 22:00:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Entergy Locates Spent Fuel Segments at Vermont Yankee ENS 406942004-04-21T21:50:00021 April 2004 21:50:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Licensee Plans to Issue News Release Regarding an Accountability Discrepancy of Snm 2017-06-03T10:15:00 | |