ENS 56584
ENS Event | |
|---|---|
09:02 Apr 28, 2023 | |
| Title | 60 Day Notification for an Invalid Actuation of Primary Containment Isolation Logic |
| Event Description | The following information was provided by the licensee email:
This telephone notification is provided in accordance with 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to report an invalid actuation of Division 2 Primary Containment Isolation logic at the Monticello Nuclear Generating Plant (MNGP) that occurred while in a refueling outage. At approximately 0402 Central Daylight Time (CDT) on April 28, 2023 and at approximately 1611 and 2143 CDT on May 4, 2023, momentary losses of 'Y80 Division 2 Uninterruptible 120VAC Class 1E Distribution Panel', which provides power to Division 2 Primary Containment Isolation logic, resulted in a partial Primary Containment Group 2 Isolation (gas systems), initiation of the Standby Gas Treatment system, and the shift of Control Room ventilation to the high radiation mode. The momentary losses of 'Y80' were due to an intermittent, age-related degradation issue with the 'Uninterruptible Power Supply Y81, Division 2 120VAC Class 1E Inverter', which resulted in a temporary loss of output plus a lack of static switch transfer from the inverter supply to the alternate source as designed. The actuations were not initiated in response to actual plant conditions, these were not intentional manual initiations, and there were no parameters satisfying the requirements for initiation. Therefore, these events have been determined to be invalid actuations that were attributed to the same cause. All systems responded as designed to the actuation signal. Operations reset the partial Primary Containment Group 2 Isolation signal, shutdown the Standby Gas Treatment system, and restored Control Room ventilation per the procedure. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Monticello  Minnesota (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1320.7 h55.029 days <br />7.861 weeks <br />1.809 months <br />) | |
| Opened: | Quinten Kovanen 09:44 Jun 22, 2023 |
| NRC Officer: | Brian P. Smith |
| Last Updated: | Jun 22, 2023 |
| 56584 - NRC Website
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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 | |