In recent years, a lengthening series of safety problems have been identified at the Palo Verde nuclear plant in Arizona. Nuclear Regulatory Commission (NRC) inspectors discovered many of the problems while several others revealed themselves during near-misses. As a direct result of these discoveries, the NRC in November 2006 rated only three of the nation's 103 operating nuclear reactors as having worse safety records than Palo Verde.

UCS is extremely troubled by the situation at Palo Verde. As bad as the long list of safety problems is, even worse is the company's unacceptable response. The company has spent millions of dollars trying to persuade the NRC that its mistakes—like deliberately draining water from the piping for emergency core cooling system pumps between 1992 and 2004, when the NRC caught them at it—aren't so bad. The smarter, responsible thing for the company to have done was to have applied those resources into seeking out and fixing other safety problems.

In an issue brief titled "How Palo Verde Made the NRC's Naughty List," UCS chronicles the abridged list of safety problems cropping up at Palo Verde in recent years that prompted the NRC to downgrade the reactors' safety rating. It is a sad story with no happy ending in sight.