Toledo, Three-sixteenths of an Inch From Chernobyl
For years, no one at Davis-Besse noticed as coolant water dripped onto the roof of the reactor vessel, a giant pot of nearly six-inch-thick carbon steel that holds the core. Or maybe they noticed, but decided it wasn't important. Either way, the coolant dripped, and the boric acid in it accumulated into a slushy little pile, and eventually the acid ate entirely through the carbon steel walls, creating a hole six inches deep, five inches long and seven inches wide.
Luckily, the inside of the vessel was coated with a three-sixteenths of an inch thick stainless-steel liner, which held off the acid--but the immense pressure inside the vessel forced it back out the hole. The Davis-Besse nuclear power plant, about forty kilometers outside of Toledo, stood three-sixteenths of an inch from a loss-of-coolant catastrophe. No one even knows how long the hole was there.
Nor was the hole formed without warning. In the summer of 2000, the NRC had put out the word: Nuclear power plant operators were to immediately inspect the nozzles of reactor vessels. Cracks in such nozzles had just been discovered at the Oconee nuclear plant in South Carolina (embarrassingly, just months after the NRC had given the plant a clean bill of health). Similar cracks were found at plants in Arkansas and Virginia. At Davis-Besse in Ohio, the acidic water was dripping from just such a nozzle crack.
After Besse-Davis eventually alerted regulators to the problem in July, 2001, the NRC admitted it failed to properly police the plant and had ignored numerous warnings; a survey of NRC employees found many concerned "that the NRC is becoming influenced by private industry," and that there is "a compromise of the [agency's] 'safety culture.' "Davis-Besse, and the plant's owners, FirstEnergy Corp., have since been in the national doghouse--not least since it's emerged that the August 2003 blackout probably originated with FirstEnergy's Ohio transmission lines. The good news is: When you've been caught in a ludicrous situation--letting acidic water drip for years onto your reactor and bringing Toledo within three-sixteenths of an inch from a possible disaster--you're free to fess up to other problems without taking much of a hit. You can even sell it as a contrite new dedication to safety.
And if you've shut down the plant anyway for embarrassing repairs, why not make all needed repairs? After all, even if it does end up costing $80 million, it's cheaper that way.
So in December, Davis-Besse became the first of the sixty-nine PWRs to confess that its containment sump pumps would probably not work if needed. "[T]he licensee stated that the recirculation sump had been declared inoperable as a result of the potential for sump clogging due to unqualified coatings [i.e., old paint] and other potential sources of post-accident debris," wrote the NRC.
In May, Davis-Besse also stated that another part of the system--high-pressure injection pumps further down the line--would also choke shut. (The Cleveland Plain Dealer, which has done excellent work on the Davis-Besse story, has a graphic here that explains it all.)