14:23 Dec 3, 2020
Valid Actuation of an Emergency Diesel Generator
At 0923 EST on December 3, 2020, with Unit 1 in Mode 1 at 100 percent power, an actuation of the Emergency AC Electrical Power System (Emergency Diesel Generator 1A) occurred during normal plant operations. The reason for Emergency Diesel Generator 1A auto start was due to Class 1E 4KV Bus 11 feeder breaker opening.
The Emergency Diesel Generator 1A automatically started as designed when the loss of voltage signal on 4KV Bus 11 was received. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in a valid actuation of the Emergency AC Electrical Power System.
There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.The cause of the 4KV Bus 11 Feeder Breaker opening is unknown at the present time and is under investigation.
|Calvert Cliffs |
Maryland (NRC Region 1)
|10 CFR 50.72(b)(3)(iv)(A), ECCS Actuation|
|Time - Person (Reporting Time:+2.78 h0.116 days <br />0.0165 weeks <br />0.00381 months <br />)|
17:10 Dec 3, 2020
|NRC Officer:||Donald Norwood|
|Last Updated:||Dec 3, 2020|
|55020 - NRC Website|