Unit 1 at Diablo Canyon nuclear power plant returned to full power Friday, after completing a planned maintenance and refueling outage that began April 23.

Nearly 1,000 contractors from all over the country came to the plant to assist regular plant employees in the event, Pacific Gas and Electric Co. officials say.

During the outage, more than 225,000 hours of inspections, maintenance and project work were completed, including replacing a portion of the reactor fuel and installing a new digital process control system.

The new system monitors and controls various systems and provides indications for the control room. The project upgraded the system from analog to digital, which increases redundancies for safety, reduces maintenance and further enhances safe operation of the facility.

Diablo Canyon is the first nuclear facility in the country to execute a digital process control system replacement of this extent using in-house resources, according to PG&E officials.