ENS 42399
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ENS Event | |
|---|---|
20:53 Mar 8, 2006 | |
| Title | Valid Actuation of Emergency Diesel Generators |
| Event Description | While restoring power to the 3C 480V Load Center following planned maintenance, the 3A safety related 4KV Bus was deenergized by the 3A Sequencer. This resulted in a valid actuation of the emergency diesel generator. The plant was in Mode 5, depressurized, with reactor coolant system level at approximately the vessel flange level. This resulted in a temporary loss of residual heat removal flow which was restored within approximately seven (7) minutes. Reactor coolant system temperature increased from 113 degrees F to 140 degrees F.
Reactor coolant system level and temperature were stabilized at pre-event values. At this time the licensee is preparing to restore off-site power to the 3A Bus and put the emergency diesel generator in standby. The licensee is also investigating the cause of the power loss to the 3A safety related 4KV Bus. The licensee will notify the NRC Resident Inspector.
In response to questions regarding the cause of the loss of the 3A 4KV bus, the following information is provided: The 3C 480 volt Load Center was de-energized for maintenance and was being restored at the time of the event. One of the maintenance activities associated with the 3C Load Center involved replacement of the 480V feeder breaker for the load center. A rotating cam inside the auxiliary switch for the replacement breaker was misaligned. The misaligned cam caused the switch contacts to operate in reverse, such that normally open contacts would be normally closed and vice versa. One of the auxiliary contacts on the 3C Load Center 480V feeder breaker provides input to the A-train Emergency Diesel Generator (EDG) Load Sequencer. With this contact operation reversed (closed vs. open with the breaker open), the Load Sequencer sensed undervoltage on the 3C Load Center, when the 4kV feeder breaker for the load center was closed. The contact being open would normally block the undervoltage signal, until the 480V feeder breaker was closed and the bus was energized. Once the A-train Load Sequencer sensed the undervoltage condition, the 3A 4kV bus was stripped and then re-energized from the 3A EDG. The licensee notified the NRC Resident Inspector. Notified R2DO (Fredrickson) |
| Where | |
|---|---|
Turkey Point  Florida (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| LER: | 05000250/LER-2006-004 |
| Time - Person (Reporting Time:+1.75 h0.0729 days <br />0.0104 weeks <br />0.0024 months <br />) | |
| Opened: | Michael Coen 22:38 Mar 8, 2006 |
| NRC Officer: | John Knoke |
| Last Updated: | Mar 9, 2006 |
| 42399 - NRC Website
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Unit 3 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 568132023-10-25T01:59:00025 October 2023 01:59:00
[Table view]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 567552023-09-22T22:19:00022 September 2023 22:19:00 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 566582023-08-04T17:20:0004 August 2023 17:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip ENS 555132021-10-09T07:00:0009 October 2021 07:00:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Auxiliary Feedwater System AUTO-STARTED on Feedwater Isolation Signal ENS 540722019-05-18T15:08:00018 May 2019 15:08:00 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 Grid Disturbance ENS 529602017-09-10T22:55:00010 September 2017 22:55:00 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 Lowering Steam Generator Water Level ENS 526232017-03-18T15:07:00018 March 2017 15:07:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Reactor Trip and Loss of Ability for Unit 4 to Supply Power to Unit 3 ENS 510652015-05-12T08:30:00012 May 2015 08:30:00 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 Main Generator Differential Trip ENS 506452014-11-30T18:54:00030 November 2014 18:54:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Auxiliary Feedwater Actuation Due to Planned Reactor Trip ENS 503542014-08-11T14:20:00011 August 2014 14:20:00 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 Loss of Instrument Air Followed by Safety Injection ENS 500542014-04-23T17:02:00023 April 2014 17:02:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation During Rod Testing ENS 489482013-04-19T21:20:00019 April 2013 21:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Due to Loss of Offsite Power Greater than 15 Minutes ENS 488212013-03-13T15:20:00013 March 2013 15:20:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Afw Actuation Due to Trip of 3B Feedwater Pump ENS 487642013-02-18T06:31:00018 February 2013 06:31:00 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 High Seal Leakoff on Reactor Coolant Pump 3A ENS 487442013-02-12T03:36:00012 February 2013 03:36:00 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 on Loss of Condenser Vacuum ENS 464192010-11-15T11:03:00015 November 2010 11:03:00 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 a Circulating Water Pump with Another Pump Out of Service for Maintenance ENS 462742010-09-23T21:14:00023 September 2010 21:14:00 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 Inadvertent Energization Generator Trip ENS 462652010-09-22T00:17:00022 September 2010 00:17:00 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 462462010-09-09T19:34:0009 September 2010 19:34:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip During Startup Due to a Control Bank Step Counter Failure ENS 462352010-09-08T17:45:0008 September 2010 17:45:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip During Maintenance on a Reactor Protection System Relay ENS 456192010-01-11T15:55:00011 January 2010 15:55:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Initiated Due to High Steam Generator Level ENS 455222009-11-27T04:40:00027 November 2009 04:40:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Two Shutdown Bank Rods Were Dropped from Fully Withdrawn Position ENS 440092008-02-26T18:09:00026 February 2008 18:09:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Units 3 and 4 Tripped Due to Grid Fluctuations ENS 423992006-03-08T20:53:0008 March 2006 20:53:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Actuation of Emergency Diesel Generators ENS 421372005-11-11T20:02:00011 November 2005 20:02:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip During Startup Following Failure of Rod Control Power Cabinet ENS 421042005-11-01T03:27:0001 November 2005 03:27:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Declaration: Loss of Offsite Power Due to Loss of Startup Transformer ENS 420562005-10-15T11:02:00015 October 2005 11:02:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Auxiliary Feedwater Actuation on a Manual Reactor Trip ENS 418002005-06-27T07:16:00027 June 2005 07:16:00 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(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Declaration of an Unusual Event Due Transformer Fire >10 Minutes ENS 415112005-03-22T08:47:00022 March 2005 08:47:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Manually Tripped Following Loss of Main Feed Pump ENS 412982004-12-29T03:46:00029 December 2004 03:46:00 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 Generator Exciter Cooling Water Leak ENS 412322004-11-30T13:50:00030 November 2004 13:50:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Dropped Control Rod ENS 412292004-11-29T05:09:00029 November 2004 05:09:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specifications Required Shutdown Due to Dropped Control Rod ENS 407522004-05-14T21:29:00014 May 2004 21:29:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Scram Due to Lowering Steam Generator Level 2023-09-22T22:19:00 | |
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