ENS 55708
ENS Event | |
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17:28 Nov 29, 2021 | |
Title | Invalid Actuation of Secondary Containment Relays |
Event Description | The following information was provided by the licensee via email:
This telephone notification is provided in accordance with 10 CFR 50.73(a)(1) to report an invalid actuation of secondary containment relays in accordance with 10 CFR 50.73(a)(2)(iv)(A). On November 29, 2021, the `B' Fuel Pool radiation monitor spiked high during restoration following the performance of the 0068 procedure `Spent Fuel Pool & Reactor Building Exhaust Plenum Monitor Calibration' due to cable to radiation monitor connector degradation from handling. This resulted in a Partial Primary Containment Group II isolation (gas systems), initiation of Standby Gas Treatment system, and isolation of the Reactor Building Ventilation system. All systems responded as designed to the actuation signal. Operations reset the Partial Primary Containment Group II isolation signal, shutdown Standby Gas Treatment System, and restored Reactor Building Ventilation system per procedures. At the time of the occurrence, the `A' Fuel Pool radiation monitor was reading normal at approximately 1.5 mr/hr. The `B' Fuel Pool radiation monitor spiked above the 50 mr/hr setpoint and continued to read erratically. Work was performed to clean and reconnect the connector and testing per 0068 procedure verified the condition was corrected. The `B' Fuel Pool radiation monitor returned to service. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
Where | |
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Monticello Minnesota (NRC Region 3) | |
Reporting | |
10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
Time - Person (Reporting Time:+1264.95 h52.706 days <br />7.529 weeks <br />1.733 months <br />) | |
Opened: | Jason Brevig 10:25 Jan 21, 2022 |
NRC Officer: | Mike Stafford |
Last Updated: | Jan 21, 2022 |
55708 - NRC Website
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Unit 1 | |
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Reactor critical | Critical |
Scram | No |
Before | Power Operation (100 %) |
After | Power Operation (100 %) |
WEEKMONTHYEARENS 565842023-04-28T09:02:00028 April 2023 09:02:00
[Table view]10 CFR 50.73(a)(1), Submit an LER 60 Day Notification for an Invalid Actuation of Primary Containment Isolation Logic ENS 557082021-11-29T17:28:00029 November 2021 17:28:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Secondary Containment Relays ENS 524512016-10-24T23:45:00024 October 2016 23:45:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification of Invalid Specified System Actuation ENS 448992009-01-20T16:10:00020 January 2009 16:10:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Secondary Containment ENS 442112008-04-03T11:25:0003 April 2008 11:25:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of a Sbgt During Annunciator Test ENS 427882006-08-19T23:49:00019 August 2006 23:49:00 10 CFR 50.73(a)(1), Submit an LER Radiation Monitor Electrical Spike Causes Secondary Containment Isolation ENS 427402006-07-30T22:30:00030 July 2006 22:30:00 10 CFR 50.73(a)(1), Submit an LER Secondary Containment Isolation Due to 'B' Spent Fuel Rad Monitor Failure ENS 426522006-06-19T04:19:00019 June 2006 04:19:00 10 CFR 50.73(a)(1), Submit an LER Radiation Monitor Spiked Three Times 2023-04-28T09:02:00 | |