ENS Event | |
|---|---|
03:05 Jul 2, 2020 | |
| Title | Loss of Offsite Power - Auto Initiation of Emergency Diesel Generator |
| Event Description | At 2305 EDT on July 1, 2020, while in Mode 5 for Refueling Outage 20 with no core alterations in progress, Fermi 2 experienced a loss of Division 2 offsite power (345 kV) which resulted in a valid automatic initiation of the Division 2 Emergency Diesel Generators (EDG) 13 and 14. EDG 13 and 14 started as expected to supply their associated busses. Division 1 offsite power remains operable and powering the Division 1 Residual Heat Removal (RHR) system in Shutdown Cooling (SDC) mode of operation. Division 1 EDGs 11 and 12 remain operable and available.
The cause of the loss of Division 2 offsite power is under review and has preliminarily been determined to be caused by Mayfly accumulation in and around the Division 2 (345 kV) switchyard. Actions have been put in place to minimize and deter Mayflies from gathering near plant switchyards. All systems responded as expected for the loss of Division 2 offsite power and no loss of SDC occurred. There was no impact to the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The event is reportable pursuant to 10 CFR 50.72(b)(3)(iv)(A), as a valid specified system actuation. |
| Where | |
|---|---|
Fermi  Michigan (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| LER: | 05000341/LER-2020-002 Valid Actuation of Emergency Diesel Generators During Partial Loss of Offsite Power |
| Time - Person (Reporting Time:+-1.07 h-0.0446 days <br />-0.00637 weeks <br />-0.00147 months <br />) | |
| Opened: | Jeffrey Myers 02:01 Jul 2, 2020 |
| NRC Officer: | Kerby Scales |
| Last Updated: | Jul 2, 2020 |
| 54761 - NRC Website
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