ENS 43676
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ENS Event | |
|---|---|
02:32 Sep 29, 2007 | |
| Title | Automatic Reactor Trip Due to Loss of a Startup Transformer |
| Event Description | On September 28, 2007, while reducing power for a planned refueling outage with the reactor at approximately 30 percent power in MODE 1, an unplanned actuation of the reactor protection system occurred. At 2232 a fault pressure trip signal was received on the A Startup Transformer (SUT), causing a loss of power to Aux Buses D, A & C electrical buses as well as the A-SA safety bus. The loss of A & C buses initiated the RCP underfrequency trip which tripped the Reactor and all three RCPs as designed. The A Diesel Generator automatically started and reenergized bus A-SA as designed. The auxiliary feedwater system actuated as expected due to undervoltage on the A-SA safety bus and loss of the main feedwater pumps. All control rods inserted on the reactor trip. The operations staff responded to the event in accordance with applicable plant procedures. The plant stabilized at normal operating no-load reactor coolant system temperature and pressure following the reactor trip. Steam generator water levels are being maintained using auxiliary feedwater. All emergency core cooling system equipment is available. The plant electrical system is being restored at this time. The A SUT remains out of service. The cause of the loss of power from A SUT is under investigation.
This condition is being reported as an unplanned reactor protection system actuation and specified system actuation in accordance with 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A). The NRC Resident Inspector was notified of this event by the licensee. The plant was in natural circulation for approximately 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. The Main Steam Isolation Valves (MSIVs) were manually isolated per procedure due to loss of EHC indication. Presently the B RCP has been restored to service, MSIVs are still closed, and the motor driven auxiliary feedwater pumps are feeding the Main Steam Generators. There are not any leaking steam generator tubes. The A EDG will be secured after backfeeding of the deenergized buses have been established. |
| Where | |
|---|---|
Harris  North Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| LER: | 05000400/LER-2007-003 |
| Time - Person (Reporting Time:+-0.22 h-0.00917 days <br />-0.00131 weeks <br />-3.01356e-4 months <br />) | |
| Opened: | M. Hinman 02:19 Sep 29, 2007 |
| NRC Officer: | John Mackinnon |
| Last Updated: | Sep 29, 2007 |
| 43676 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (30 %) |
| After | Hot Standby (0 %) |
Harris with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 561902022-10-31T00:57:00031 October 2022 00:57:00
[Table view]10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation - Auxiliary Feedwater System Actuation ENS 561892022-10-30T10:53:00030 October 2022 10:53:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip and Auxiliary Feedwater System Actuation ENS 560752022-08-28T07:29:00028 August 2022 07:29:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip and Auxiliary Feedwater System Actuation ENS 558682022-04-29T08:05:00029 April 2022 08:05:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip and Auxiliary Feedwater System Actuation ENS 550382020-12-16T13:51:00016 December 2020 13:51:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip Due to Generator Lockout ENS 548342020-08-13T13:38:00013 August 2020 13:38:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Dropped Control Rod ENS 545992020-03-23T14:13:00023 March 2020 14:13:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip ENS 533182018-04-07T08:51:0007 April 2018 08:51:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Actuation of Auxiliary Feedwater System (Afw) ENS 523352016-10-26T15:42:00026 October 2016 15:42:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Containment Sump Suction Valve Opened During Containment Spray Pump Testing ENS 522912016-10-08T17:28:0008 October 2016 17:28:00 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, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Unusual Event Declared Due to Loss of Offsite Power ENS 522892016-10-08T05:50:0008 October 2016 05:50:00 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)(iv)(A), System Actuation - ECCS Discharge Unplanned Reactor Trip and Safety Injection Due to Turbine Control Valve Transient ENS 497422014-01-18T15:16:00018 January 2014 15:16:00 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 Alert Declared Due to Fire in 480V Bus ENS 463962010-11-05T05:04:0005 November 2010 05:04:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Actuation of an Emergency Diesel Generator Following Inadvertent De-Energization of Safety Bus ENS 454992009-11-16T03:42:00016 November 2009 03:42:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Main Generator Oil Leak ENS 444232008-08-19T13:05:00019 August 2008 13:05:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Rod Control System Malfunctioned ENS 444042008-08-11T04:49:00011 August 2008 04:49:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Degrading Condenser Vacuum ENS 436762007-09-29T02:32:00029 September 2007 02:32:00 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 Loss of a Startup Transformer ENS 428482006-09-19T14:00:00019 September 2006 14:00:00 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 Signal ENS 416542005-05-01T04:21:0001 May 2005 04:21:00 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 Condensate Pump ENS 411792004-11-07T21:35:0007 November 2004 21:35:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation "a" Auxiliary Feedwater (Afw) Pump Manually Started Due to Decreasing Steam Generator Water Level. ENS 411292004-10-18T11:41:00018 October 2004 11:41:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unplanned Emergency Diesel Start ENS 407302004-05-06T16:52:0006 May 2004 16:52:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip and Actuation of Auxiliary Feedwater System ENS 400842003-08-17T19:51:00017 August 2003 19:51:00 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" Condensate Pump. 2022-08-28T07:29:00 | |
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