ENS 55660
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ENS Event | |
|---|---|
13:05 Oct 20, 2021 | |
| Title | Invalid Actuation of a General Containment Isolation Signal Affecting More than One System |
| Event Description |
This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation of the Reactor Protection System (RPS). On October 20, 2021, at approximately 0705 hours0.00816 days <br />0.196 hours <br />0.00117 weeks <br />2.682525e-4 months <br /> Central Daylight Time (CDT), Browns Ferry, Unit 1, 1B RPS bus unexpectedly lost power. The loss of the bus resulted in a half scram, automatic Primary Containment Isolation System (PCIS) Groups 2, 3, 6, and 8 isolations, and Trains A, B, and C SBGT [Stand-By Gas Treatment] and A CREV [Control Room Emergency Ventilation system] started. All systems responded as expected. At 0720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> CDT, the bus was placed on the alternate power supply and the half scram and PCIS isolations were reset. Plant conditions which initiate PCIS Group 2 actuations are Reactor Vessel Low Water Level (Level 3) or High Drywell Pressure. The PCIS Group 3 actuations are initiated by Reactor Vessel Low Water Level (Level 3) or Reactor Water Cleanup Area High Temperature. The PCIS Group 6 actuations are initiated by Reactor Vessel Low Water Level (Level 3), High Drywell Pressure, or Reactor Building Ventilation Exhaust High Radiation (Reactor Zone or Refuel Zone). The PCIS Group 8 actuations are initiated by Low Reactor Vessel Water Level (Level 3) or High Drywell Pressure. At the time of the event, these conditions did not exist; therefore, the actuation of the PCIS was invalid. The cause of the RPS bus loss was a trip of the underfrequency relay due to drift of the relay setpoint. The relay was replaced and 1B RPS bus was returned to the normal power supply on October 21, 2021, at 0510 hours0.0059 days <br />0.142 hours <br />8.43254e-4 weeks <br />1.94055e-4 months <br /> CDT. There were no safety consequences or impact to the health and safety of the public as a result of this event. This event was entered into the Corrective Action Program as Condition Report 1729592. The NRC Resident Inspector has been notified of this event. |
| Where | |
|---|---|
Browns Ferry  Alabama (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1368.87 h57.036 days <br />8.148 weeks <br />1.875 months <br />) | |
| Opened: | Mark Acker 14:57 Dec 16, 2021 |
| NRC Officer: | Brian Lin |
| Last Updated: | Dec 16, 2021 |
| 55660 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 556602021-10-20T13:05:00020 October 2021 13:05:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of a General Containment Isolation Signal Affecting More than One System ENS 552872021-04-01T18:02:0001 April 2021 18:02:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Telephonic Notification of Invalid Actuation of a General Containment Isolation Signal Affecting More than One System ENS 549322020-08-06T22:49:0006 August 2020 22:49:00 10 CFR 50.73(a)(1), Submit an LER | 60-Day Optional Telephonic Notification of an Invalid Actuation of a General Containment Isolation Signal Affecting More than One System ENS 549312020-08-06T06:28:0006 August 2020 06:28:00 10 CFR 50.73(a)(1), Submit an LER | 60-Day Optional Telephonic Notification of an Invalid Specified System Actuation ENS 547092020-03-16T06:02:00016 March 2020 06:02:00 10 CFR 50.73(a)(1), Submit an LER Invalid Specified System Actuation ENS 546972020-03-09T01:21:0009 March 2020 01:21:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of a General Containment Isolation Signal Affecting More than One System ENS 543322019-08-20T16:33:00020 August 2019 16:33:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification of Invalid Specified System Actuation ENS 543002019-07-31T21:50:00031 July 2019 21:50:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification Due to an Invalid Actuation of a Containment Isolation Signal ENS 543412018-12-29T07:20:00029 December 2018 07:20:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of a Signal Affecting More than One System ENS 536612018-08-16T05:00:00016 August 2018 05:00:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of a General Containment Isolation Signal Affecting More than One System ENS 530702017-01-10T09:00:00010 January 2017 09:00:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of a General Containment Isolation Signal Affecting More than One System ENS 516282015-11-06T14:15:0006 November 2015 14:15:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of an Emergency Diesel Generator ENS 510852015-04-05T09:35:0005 April 2015 09:35:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification for an Invalid Primary Containment Isolation System Actuation ENS 507542014-11-26T20:27:00026 November 2014 20:27:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of a General Containment Isolation Signal Affecting More than One System ENS 506582014-10-07T15:35:0007 October 2014 15:35:00 10 CFR 50.73(a)(1), Submit an LER Invalid Specified System Actuation ENS 505652014-08-27T16:09:00027 August 2014 16:09:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of General Containment Isolation Signals ENS 499422014-01-21T13:46:00021 January 2014 13:46:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Optional Telephone Notification of an Invalid Primary Containment Isolation Signal ENS 490772013-04-09T10:06:0009 April 2013 10:06:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Report of an Invalid Primary Containment System Isolation Signal ENS 486902012-11-23T10:35:00023 November 2012 10:35:00 10 CFR 50.73(a)(1), Submit an LER Primary Containment Isolation Actuation Signal During Surveillance ENS 485872012-10-18T05:01:00018 October 2012 05:01:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Telephone Notification of an Invalid System Actuation ENS 485682012-10-09T16:50:0009 October 2012 16:50:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Telephonic Notification of an Invalid System Actuation ENS 485062012-09-18T06:45:00018 September 2012 06:45:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification of Invalid Actuation of Containment Isolation Signals ENS 485052012-09-17T09:12:00017 September 2012 09:12:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification of Invalid Actuation of Containment Isolation Signals ENS 480822012-05-19T05:06:00019 May 2012 05:06:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification of Invalid Specified System Actuation ENS 480062012-04-11T20:15:00011 April 2012 20:15:00 10 CFR 50.73(a)(1), Submit an LER Invalid System Actuation Resulting from Post Maintenance Testing ENS 474502011-09-19T16:00:00019 September 2011 16:00:00 10 CFR 50.73(a)(1), Submit an LER Invalid Group 6 Isolation Signal ENS 470032011-05-01T07:44:0001 May 2011 07:44:00 10 CFR 50.73(a)(1), Submit an LER Invalid Rps (Scram) Actuation ENS 468802011-03-30T19:43:00030 March 2011 19:43:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Telephonic Notification of Invalid Rps Signal Due to Loss of Variable Leg of Level Transmitter ENS 468812011-03-27T01:05:00027 March 2011 01:05:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Telephonic Notification of Invalid Primary Containment Isolation Signal Due to Maintenance ENS 466562011-01-03T21:15:0003 January 2011 21:15:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Telephone Notificaton Concerning Invalid Containment Isolation System Actuations ENS 460662010-07-02T17:32:0002 July 2010 17:32:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation System Actuation from a Loss of Power to the Reactor Protection System (Rps) 3A ENS 460542010-04-30T21:48:00030 April 2010 21:48:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation System (Pcis) Actuation from a Loss-Of-Power to Reactor Protection System (Rps) 1A ENS 460462010-04-27T22:37:00027 April 2010 22:37:00 10 CFR 50.73(a)(1), Submit an LER Invalid Group 6 Containment Isolation ENS 442942008-04-14T18:08:00014 April 2008 18:08:00 10 CFR 50.73(a)(1), Submit an LER Inadvertant Deenergization of Group Six Logic Circuit ENS 430832006-11-10T06:10:00010 November 2006 06:10:00 10 CFR 50.73(a)(1), Submit an LER Edg Actuation Due to Accidental Switch Mispositioning ENS 428782006-08-20T01:02:00020 August 2006 01:02:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation System Actuation ENS 428772006-08-19T00:58:00019 August 2006 00:58:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation System (Pcis) Actuation ENS 428672006-08-09T14:51:0009 August 2006 14:51:00 10 CFR 50.73(a)(1), Submit an LER Invalid Eecw Pump Actuation During Testing ENS 428372006-07-18T09:47:00018 July 2006 09:47:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation System Actuation Due to Loss of Power to One Reactor Protection System Bus ENS 423892006-01-13T17:57:00013 January 2006 17:57:00 10 CFR 50.73(a)(1), Submit an LER Unplanned, Invalid Actuation of Emergency Diesel Generator ENS 422152005-11-15T14:05:00015 November 2005 14:05:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation System (Pcis) Actuation ENS 411812004-09-28T18:02:00028 September 2004 18:02:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation System Actuation from Loss-Of-Power to Reactor Protection System (Rps) Bus 2A ENS 411802004-09-25T23:14:00025 September 2004 23:14:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation System Actuation from Loss-Of-Power to Reactor Protection System (Rps) Bus 3B 2021-04-01T18:02:00 [Table view] | |
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