ENS 42725
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ENS Event | |
|---|---|
13:45 Jul 25, 2006 | |
| Title | Reactor Trip Breakers Opened During Maintenance on Steam Generator Wide Level Channels |
| Event Description | The licensee was performing maintenance on "D" Steam Generator Low Level bistables when 4 (four) out of 8 (eight) trip control breakers opened possibly due to a 24 V DC power supply transient to 2 (two) of 4 (four) logic matrix relays. The reactor trip logic was verified to be functional and capable of processing valid reactor trip signals. The actuation was invalid as no plant transient occurred and no process variable was exceeded which would otherwise have required a reactor trip.
The licensee notified the State and the NRC Resident Inspector.
Upon further review, the initial notification of this event is determined to have been conservative. A review of NUREG 1022, Rev. 2, 'Event Reporting Guidelines, 10 CFR 50.72 and 50.73,' as well as the supporting comments in the notice of final rulemaking for changes to 10 CFR Parts 50 and 72 contained in the Federal Register on October 25, 2000, indicates that these documents stress the need for reporting of system actuations. As stated in NUREG 1022, 'actuation of multichannel actuation systems is defined as actuation of enough channels to complete the minimum actuation logic. Therefore, single channel actuation logic,' Per the final rulemaking, 'the principal reason for reporting an actuation of one of these systems is that it is indicative of an unplanned plant transient that the NRC needs to evaluate to determine if action is necessary to address a safety problem.' In the event described in CR-06-06880, a portion of the RPS actuation sufficiently to cause four of the eight TCBs to open (i.e, a half trip), but not enough channels actuated to complete the minimum actuation logic for RPS (i.e, insufficient channels to fulfill the safety function of the RPS to deenergized the control rod drive mechanisms to shutdown the reactor). There was no unplanned plant transient as a result of the half trip. Determination Based on the above assessment, this condition in NOT reportable per 10 CFR 50.73(a)(2)(iv)(A) as an actuation of any of the systems listed in paragraph 10 CFR 50.73(a)(2)(iv)(B). Accordingly, the report of a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> non-emergency event under 10 CFR 50.72(b)(2)(iv)(b) for a half RPS trip actuation should be withdrawn. R1DO (Lorson) notified. The NRC Resident Inspector will be notified by the licensee of this retraction. |
| Where | |
|---|---|
Millstone  Connecticut (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation | |
| Time - Person (Reporting Time:+-2.07 h-0.0863 days <br />-0.0123 weeks <br />-0.00284 months <br />) | |
| Opened: | Jeff Young 11:41 Jul 25, 2006 |
| NRC Officer: | Arlon Costa |
| Last Updated: | Aug 14, 2006 |
| 42725 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 565442023-05-30T08:46:00030 May 2023 08:46:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip ENS 546632020-04-13T19:50:00013 April 2020 19:50:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Trip Due to Low Condenser Vacuum ENS 546312020-04-01T20:25:0001 April 2020 20:25:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip Due to Circuit Fault ENS 544572019-12-27T12:04:00027 December 2019 12:04:00 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 Feedwater Pump Trip ENS 521692016-08-11T13:59:00011 August 2016 13:59:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Loss of Two Circulating Water Pumps ENS 519292016-05-15T10:38:00015 May 2016 10:38:00 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 Due to Main Generator Hydrogen Leak in Turbine Building ENS 516822016-01-25T06:47:00025 January 2016 06:47:00 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 Reactor Coolant Pump Trip ENS 515212015-11-08T07:30:0008 November 2015 07:30:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Reactor Coolant Pump Oil Leak ENS 501422014-05-25T11:02:00025 May 2014 11:02:00 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, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Unusual Event Due to Loss of Offsite Power ENS 501412014-05-25T11:02:00025 May 2014 11:02:00 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 Due to Loss of Offsite Power ENS 495252013-11-09T20:13:0009 November 2013 20:13:00 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 Loss of Condenser Vacuum ENS 492602013-08-10T01:19:00010 August 2013 01:19:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip on Low Steam Generator Water Level ENS 520002013-06-13T00:13:00013 June 2013 00:13:00 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)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown and Reactor Trip ENS 474612011-11-20T22:58:00020 November 2011 22:58:00 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 Condenser Vacuum During Startup ENS 469712011-06-20T15:52:00020 June 2011 15:52:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 2 Reactor Trip Following the Loss of the "B" Main Feedwater (Mfw) Pump ENS 464412010-11-28T20:15:00028 November 2010 20:15:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip After Turbine Trip Due to Loss of Condenser Vacuum ENS 459452010-05-22T20:45:00022 May 2010 20:45:00 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 Loss of Steam Generator Water Level Control ENS 459312010-05-17T14:17:00017 May 2010 14:17:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to Low Steam Generator Water Level ENS 457292010-02-26T16:25:00026 February 2010 16:25:00 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 Two Circulating Water Pumps ENS 455832009-12-20T03:53:00020 December 2009 03:53:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Caused by a Turbine/Generator Electrical Fault ENS 451832009-07-03T17:05:0003 July 2009 17:05:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Trip Resulting from Turbine Trip ENS 445642008-10-12T02:36:00012 October 2008 02:36:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Trip/ Automatic Reactor Trip on Low Steam Generator Level ENS 443262008-06-28T15:46:00028 June 2008 15:46:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Loss of Both Feedwater Pumps ENS 442382008-05-24T13:54:00024 May 2008 13:54:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Loss of Offsite Power ENS 442342008-05-22T18:20:00022 May 2008 18:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Trip Due to Lightning Strike ENS 427252006-07-25T13:45:00025 July 2006 13:45:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Trip Breakers Opened During Maintenance on Steam Generator Wide Level Channels ENS 423672006-02-23T15:22:00023 February 2006 15:22:00 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 Main Feedwater ENS 421802005-12-01T19:45:0001 December 2005 19:45:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to Low Steam Generator Level ENS 420242005-09-29T17:10:00029 September 2005 17:10:00 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 Circulating Water Pumps ENS 416072005-04-17T12:42:00017 April 2005 12:42:00 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, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Alert Declared Due to Unit 3 Main Steam Relief Valves Not Reseating After Actuation ENS 405912004-03-16T01:20:00016 March 2004 01:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip at Millstone 2 Due to Spurious Loss of One Main Feed Pump ENS 405702004-03-06T05:50:0006 March 2004 05:50:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip at Millstone 2 Due to Spurious Trip of the "B" Feed Pump ENS 403612003-11-29T03:05:00029 November 2003 03:05:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip from 11% Power Due to Turbine Vibration ENS 403582003-11-27T11:29:00027 November 2003 11:29:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Plant Had a Manual Reactor Trip from 23% Power Due to Turbine Vibration 2023-05-30T08:46:00 | |
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