ENS 46748
ENS Event | |
|---|---|
03:15 Apr 13, 2011 | |
| Title | Esf Actuation Following Loss of a Safeguard Bus During Edg Testing |
| Event Description | The following event occurred with the unit in a "No Mode" defueled condition.
On the 12th of April at 2215 CDT Comanche Peak Nuclear Power Plant Unit 2 had a Train B ESF Actuation (Black Out) reportable per 10CFR50.72(b)(3)(iv) for [the 6.9KV Train B] Emergency AC Electrical power systems including Emergency Diesel Generator (EDG). At the time of the event, Unit 2 was in 'No Mode' - the core was off loaded and post maintenance testing was being performed on the 2-02 Emergency Diesel Generator. The scope of the EDG testing was to verify proper operation of the EDG when it was the sole supply to the Unit 2 Train B 6.9KV safeguards buses. Unit 2 Train B 6.9 KV buses have 3 AC sources - XST1 (138KV) preferred source, XST2 (345KV) alternate source and the 2-02 Emergency Diesel Generator. The 2-02 EDG was started normally and was operating in parallel with XST1 (preferred AC source) just before the event. The event was triggered when the preferred AC supply breaker to the Train B 6.9KV Safeguard bus was opened per plan. The opening of the preferred feeder breaker resulted in the 2-02 EDG being the sole AC source to the Train B 6.9KV bus. Immediately following this breaker operation, the EDG tripped on an Auto Voltage Regulator failure. This caused the Train B 6.9KV safeguard bus to de-energize which resulted in the automatic closure of the alternate AC (XST2) feeder breaker. This in turn triggered the Train B Solid State Sequencer to sequence on Train B Black Out loads - as designed. The Train B Black Out Solid State Sequencer operated as designed. No abnormalities were noted. All available equipment operated as designed. The 2-02 EDG is currently tagged out and the problem associated with the [Auto Voltage Regulator] failure is being investigated. [The] NRC Resident Inspector has been informed and is currently located on site. No fuel movement was in progress during this event. Train A safeguard power was unaffected and available throughout. Non-safety related power was also not affected. The only operational impact was the loss of a Train B spent fuel pool cooling pump for approximately 10 minutes. The spent fuel pool temperature increased approximately 1/2 degree during before cooling was restored.
Further investigation of this event has determined that the 2-02 Emergency Diesel Generator (EDG) auto voltage regulator functioned as designed. The EDG did not receive an emergency start signal, which was consistent with the design for the plant conditions present. In addition, Unit 2 was defueled and in a 'No Mode' condition, and there was no actuation of any of the systems listed in paragraph 50.72 (b)(3)(iv)(B) by the sequencer operation. Therefore, this event is not reportable because it did not meet the criteria for a system actuation per 50.72(b)(3)(iv)(A) and the guidance in NUREG-1022. The licensee will be notifying the NRC Resident Inspector. Notified R4DO (Miller). |
| Where | |
|---|---|
Comanche Peak  Texas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-1.3 h-0.0542 days <br />-0.00774 weeks <br />-0.00178 months <br />) | |
| Opened: | Ed Lessmann 01:57 Apr 13, 2011 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Apr 14, 2011 |
| 46748 - NRC Website | |
WEEKMONTHYEARENS 570332024-03-17T20:15:00017 March 2024 20:15:00
[Table view]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 Main Feedwater Pump Trip ENS 570242024-03-12T13:16:00012 March 2024 13:16:00 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 565802023-06-16T23:32:00016 June 2023 23:32:00 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 LO-LO Steam Generator Level ENS 560912022-09-06T04:45:0006 September 2022 04:45:00 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 Turbine Trip ENS 540642019-05-15T02:51:00015 May 2019 02:51:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Voltage Transient Due to Loss of Offsite Switchyard ENS 539062019-03-02T09:17:0002 March 2019 09:17:00 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 Feedwater Isolation Valve Closure ENS 537672018-12-03T06:00:0003 December 2018 06:00:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Actuation of Blackout Sequencers Due to Loss of One Offsite Power Source ENS 535502018-08-13T05:00:00013 August 2018 05:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to Generator Lockout ENS 530912017-11-26T02:25:00026 November 2017 02:25:00 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 Main Feed Water ENS 529452017-09-02T02:40:0002 September 2017 02:40:00 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 Two Dropped Rods ENS 528982017-08-11T16:24:00011 August 2017 16:24:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Comanche Peak Automatic Turbine Trip from 10 Percent Power ENS 514442015-10-03T15:00:0003 October 2015 15:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip During Shutdown for a Refueling Outage ENS 497432014-01-18T14:40:00018 January 2014 14:40:00 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 Turbine Trip ENS 496062013-12-04T19:50:0004 December 2013 19:50:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event - Loss of Startup Power Due to a Cut Cable ENS 494972013-11-02T02:47:0002 November 2013 02:47:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip During Solid State Protection System Testing ENS 485142012-11-17T16:23:00017 November 2012 16:23:00 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 484752012-11-02T06:42:0002 November 2012 06:42:00 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 Reactor Coolant Pump Motor Bearing Temperature ENS 468632011-05-19T19:07:00019 May 2011 19:07:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip After a Main Condenser Tube Leak ENS 467482011-04-13T03:15:00013 April 2011 03:15:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Esf Actuation Following Loss of a Safeguard Bus During Edg Testing ENS 458332010-04-12T12:21:00012 April 2010 12:21:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Actuation of Blackout Sequencers Due to Loss of One Offsite Power Source ENS 456172010-01-09T16:28:0009 January 2010 16:28:00 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 Sudden Pressure in Output Transformer ENS 440672008-03-16T16:37:00016 March 2008 16:37:00 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 Broken Sensing Line ENS 429452006-10-29T21:20:00029 October 2006 21:20:00 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 Lowering Steam Generator Level ENS 429372006-10-27T08:08:00027 October 2006 08:08:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Loss of Both Main Feed Pumps ENS 414322005-02-23T07:53:00023 February 2005 07:53:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Auxiliary Feedwater Action Following Momentary Power Interruption ENS 411342004-10-19T10:28:00019 October 2004 10:28:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Normal Power Supply to "2E" Switchgear Resulted in Afw Autostart ENS 404062003-12-22T14:27:00022 December 2003 14:27:00 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 Turbine Trip 2024-03-17T20:15:00 | |