PHOENIX - The Nuclear Regulatory Commission's chairman on Friday toured the Palo Verde Nuclear Generation Station and met with its operators, a day after the federal agency downgraded the safety rating of the nation's largest nuclear plant.
The NRC's downgrade of Palo Verde followed a series of problems - most recently the discovery in September that an emergency diesel generator had been broken for 18 days. Emergency generators at nuclear reactors provide electricity to pumps, valves and control rooms if the main electrical supply fails.
NRC Chairman Dale Klein had previously planned to visit Palo Verde but moved up his visit because of the downgrade, NRC spokesman Victor Dricks said Friday. "It was given a higher priority."
Workers previously have found leaking oil seals in reactor coolant pumps and potential problems with a so-called dry pipe that could have disrupted the flow of water to the emergency core-cooling system. Federal inspectors also have said engineers and staff haven't always followed technical requirements when restarting the reactors.
The NRC said Thursday it will step up its inspections of Palo Verde and require APS to develop a plan identifying Palo Verde's safety deficiencies and setting a course to fix the shortfalls.
Only FirstEnergy Corp.'s Perry nuclear plant in Ohio now has a safety rating as bad as Palo Verde's, Dricks said Thursday.
Arizona Public Service Co., the plant's operator and a subsidiary of Phoenix-based Pinnacle West Capital Corp., responded to the downgrade by saying it would not appeal the ruling and plans to guide Palo Verde "to a state of excellence."
APS spokesman Jim McDonald said the company's top nuclear official, Randy Edington, was reviewing an improvement plan drafted by previous management and will draft a new version in consultation with NRC officials.
Edington was hired in January to oversee operations after the company's former chief nuclear engineer retired.
The uranium-fueled three-reactor plant is located approximately 50 miles west of downtown Phoenix. It is owned by utilities in Arizona, California, New Mexico and Texas.