ENS 49358
ENS Event | |
|---|---|
04:00 Jul 23, 2013 | |
| Title | Invalid Primary Containment Isolation System Group 3 Actuation |
| Event Description | This notification is being made in accordance with 10CFR50.73 (a)(2)(iv)(A) to provide information pertaining to an invalid Primary Containment Isolation System (PCIS) Group 3 actuation signal that affected containment valves in more than one system.
On 7/23/2013, and again on 7/24/2013, with the reactor at 100% power, an invalid PCIS Group 3 actuation occurred from a momentary spike of the 'B' Reactor Building ventilation radiation monitor which reached the instrument's high radiation trip set point. A radiation protection technician was dispatched and radiation levels in the vicinity of the 'B' radiation monitor were verified to be normal and below the alarm set points. The radiation monitor was verified to be indicating normal expected radiation levels. Subsequent visual inspection and functional checks of the radiation monitors were completed satisfactory and the instrument channel was returned to service. At the recommendation from the vendor, the detectors were replaced in both of the Reactor Building ventilation monitors as well as the Refuel Floor radiation monitors. On 8/19/2013, 9/12/2013, and 9/13/2013, with the reactor at 100% power, invalid PCIS Group 3 actuations occurred from a momentary spike of the 'A' Refuel Floor radiation monitor which reached the instrument's high radiation trip set point. A radiation protection technician was dispatched to the refuel floor and dose rates in the vicinity of the 'A' radiation monitor detector were verified to be normal and below the alarm set points. The radiation monitor was verified to be indicating normal expected radiation levels. Subsequent visual inspection and functional checks of the radiation monitors were completed satisfactory and the instrument channel was returned to service. Both trains of Standby Gas Treatment System started as designed and Reactor Building ventilation isolated as a result of the invalid PCIS actuation. The PCIS functioned successfully providing a complete Group 3 isolation. The PCIS Group 3 isolation involves the following systems: Drywell and Suppression Chamber air and vent: V16-19-6A, 6B, 7, 7A, 7B, 8, 9, 10, 23 Containment Makeup: V-16-20-20, 22A, 22B Containment Air Sampling: VG-23, 26, V109-76A, 76B Containment Air compressor suction: V72-38A, 38B Containment Air Dilution: VG-9A, 9B, 22A, 22B, NG-11A, 11B, 12A, 12B, 13A, 13B Since no actual high radiation condition existed which required the PCIS Group 3 isolation, and the actuation was not in response to actual plant conditions satisfying the requirements for isolation, this event has been classified as an invalid actuation. This event did not result in any adverse impact to the health and safety of the public. In accordance with 10CFR50.73(a)(1) a telephone notification is being made instead of submitting a written Licensee Event Report. The licensee has notified the NRC resident inspector. |
| Where | |
|---|---|
Vermont Yankee  Vermont (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1401.28 h58.387 days <br />8.341 weeks <br />1.919 months <br />) | |
| Opened: | Benjamin Agnew 13:17 Sep 19, 2013 |
| NRC Officer: | Charles Teal |
| Last Updated: | Sep 19, 2013 |
| 49358 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 501642014-04-05T11:00:0005 April 2014 11:00:00
[Table view]10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation System Actuation ENS 498252013-12-15T05:00:00015 December 2013 05:00:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Optional Telephone Notification of Invalid Pcis System Actuation ENS 493582013-07-23T04:00:00023 July 2013 04:00:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation System Group 3 Actuation ENS 492112013-06-14T22:06:00014 June 2013 22:06:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation System Actuation Due to a Radiation Monitor Spike ENS 475002011-10-11T21:29:00011 October 2011 21:29:00 10 CFR 50.73(a)(1), Submit an LER Loss of Vital Ac Power While Shutdown ENS 460702010-05-17T04:00:00017 May 2010 04:00:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Report - Invalid Actuation of Hpci and Rcic Systems ENS 450092009-03-24T17:26:00024 March 2009 17:26:00 10 CFR 50.73(a)(1), Submit an LER Primary Containment Isolation System (Pcis) Group 3 Invalid Actuation ENS 437292007-09-15T04:00:00015 September 2007 04:00:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation ENS 421202005-11-04T21:08:0004 November 2005 21:08:00 10 CFR 50.73(a)(1), Submit an LER Temporary Loss of the Running Rhr Pump During a Bus Transfer ENS 422352005-11-03T00:01:0003 November 2005 00:01:00 10 CFR 50.73(a)(1), Submit an LER Inadvertent Containment Isolation Signal Affecting Containment Isolation Valves ENS 410042004-07-31T17:56:00031 July 2004 17:56:00 10 CFR 50.73(a)(1), Submit an LER Invalid Pcis Actuation ENS 403712003-10-31T05:00:00031 October 2003 05:00:00 10 CFR 50.73(a)(1), Submit an LER Invalid Group Iii Primary Containment Isolation System Actuation 2014-04-05T11:00:00 | |