But by the end of the Cold War, all the reactors had been shut down, and the challenge fell to the Department of Energy to clean up the contamination.The legacy of Hanford is now measured in half-lives.
In 1948, a dike at a reactor waste pond broke, dumping 28 pounds of uranium into the Columbia River. A federal report released in 1992 estimated that 685,000 curies of radioactive iodine-131 had been released into the river and air from the Hanford site between 1944 and 1947.
In comparison, about 43,000 curies of radioactive krypton and less than 20 curies of the particularly hazardous iodine-131 were released in the 1979 Three Mile Island nuclear accident. Exposure to iodine-131 can increase the risk of thyroid cancer.
Today, scientists and biologists extensively test almost every creature along the river, whether a tadpole or a deer.
Critics say that tourists who occasionally visit the Hanford Reach should be safe but that locals who regularly swim in, go boating on and eat fish from the river may have a higher risk of exposure to harmful contaminants, a charge that state health officials dispute.
"Would I eat fish out of that river? No way," said Gregory deBruler, an environmental health specialist with the Columbia Riverkeeper, a nonprofit environmental group dedicated to protecting the river.
A spokeswoman for the Washington State Department of Health's Office of Radiation Protection said that tests of fish from the river had not detected levels exceeding public health standards for radiation.
The task of cleaning up the mess has been daunting, involving the removal of millions of gallons of contaminated ground water, hundreds of tanks of liquid radioactive waste and thousands of tons of spent nuclear fuel. Even the tumbleweeds that blow across the site are scanned for radiation before being carted away for disposal.
Department of Energy officials say they don't know how long the cleanup work will take because they still don't know the extent of the contamination. The agency has built a massive landfill at the Hanford site to hold up to 10 million tons of contaminated materials. The still-radioactive cores of the reactors will be entombed in 4-foot-thick walls of concrete and steel for a minimum of 75 years. All the nuclear facilities except the B reactor will be off-limits to the public while the soil cleanup continues.
