The U.S. Nuclear Regulatory Commission (NRC) was notified August 9 after the loss of a non-vital 480 V bus resulted in a feedwater transient that caused the steam generator water level to fall below the automatic reactor trip point, according to the NRC. The reactor responded as designed with all rods being inserted into the core.
An auxiliary feedwater system automatically started and is currently feeding the steam generators, according to Power Engineering. There is no danger to the public or to the workers.
There is no word on when the reactor will return to operation. Unit 2 continues to operate at full power.
Unit 2 had to shut down last August after workers with Dominion discovered cooling water was 1.7 degrees above the limit.