Unit 2 of the Diablo Canyon nuclear power plant was restarted Tuesday after a maintenance and refueling shutdown.
Plant workers, along with more than 1,000 temporary workers, replaced one-third of the reactor fuel and performed numerous maintenance and testing tasks. They also replaced the reactor vessel head, a component that sits atop the reactor and helps maintain pressure in it.
Also during this outage, workers discovered that switches on two safety valves were improperly set during the previous outage that occurred a year and a half ago. The valves were set in such a way that they could not have been opened remotely during a loss-of-coolant accident.
— David Sneed