Unit 2 at Diablo Canyon Power Plant has returned to service and is now operating at 100-percent power after the nuclear reactor detected a fault and shut down five days ago, according to plant owner Pacific Gas and Electric Co.
A PG&E spokeswoman said a grid monitoring device detected a lower-than-normal current on the transmission lines Saturday and Unit 2 automatically went offline to protect equipment.
She did not say what caused the transmission line current to be lower than normal.
The Unit 1 reactor is currently operating at 55-percent power while maintenance activities are underway, the spokeswoman said.
When both units are operating at full power, Diablo Canyon's twin reactors produce a total of approximately 2,300 net megawatts of electricity, providing more than 20 percent of the power PG&E delivers to its customers.