PHOENIX -- A Palo Verde Nuclear Generating Station reactor unit is nearly back to full production after what's described as a minor explosion in an electrical cabinet.
Arizona Public Service Co. reported the Tuesday night incident as an "unusual event," the lowest of four emergency levels classified by the federal Nuclear Regulatory Commission.
APS spokesman Betty Dayyo said the explosion consisted of arcing inside a cabinet that routes electricity to equipment in a turbine building.
Dayyo said the cause is under investigation.
APS said no radioactive material was released from the three-reactor plant 50 miles west of downtown Phoenix.
Arizona, California, New Mexico and Texas utilities own the plant.
Palo Verde's Unit 1 reduced its power production to 60 percent but started ramping back up Thursday, reaching 93 percent by Friday morning.