Hanford workers have finished cleaning up a Hanford reactor site for the first time, the Department of Energy announced Wednesday.
Gone is the industrial complex with more than 100 buildings that once surrounded F Reactor, Hanford's third plutonium production reactor along the Columbia River.
Contaminated soil and waste sites -- where debris was disposed of in unlined pits and trenches -- have been dug up. What remained of Hanford's former experimental animal farm, including buried carcasses and radioactive manure, was hauled off.
Now most of the 2-square-mile complex looks much as it did before settlers began arriving, only to have to give up their farms and homes during World War II to make way for the Manhattan Project.
An expanse of sagebrush stretches from what remains of F Reactor to the blue of the Columbia River.
"It's a momentous occasion," said Matt McCormick, manager of the DOE Hanford Richland Operations Office, at Wednesday's brief ceremony with contractor Washington Closure Hanford to mark completion. "You guys removed the source of contamination that could threaten the Columbia River."
Hanford had nine plutonium-production reactors, arranged in six areas around the horn of the river as it cuts through the nuclear reservation. F Reactor was farthest downstream and nearest to Richland.
The work at F Reactor "really was the proving ground for the methodologies and the closure documentation to wrap it up in a bow and say 'We are complete,' " said Carol Johnson, Washington Closure president.
Early in the environmental cleanup was the "cocooning" of F Reactor, which dates to World War II and continued producing plutonium for the nation's Cold War nuclear weapons program until 1965.
F Reactor was torn down to little more than its radioactive core, sealed up and reroofed to let radiation decay to more manageable levels over 75 years. That work was completed in 2003.
The boxy building that boaters can see from the river is the only above-ground structure that remains of what McCormick said once looked like a small city.
Workers also left a second structure, an underground concrete clearwell that held filtered water to cool the reactor.
After the clearwell stopped operating about 35 years ago, bats moved in to roost from spring to fall. Now, the approximately 6,000 bats form the largest known maternity colony of Yuma bats in Eastern Washington.
The clearwell, about the size of a football field, has 98 pillars holding up its ground-level top. The bats move up and down the pillars to find optimum temperatures of up to 110 degrees under the sun-heated concrete.
At night, the bats fly out to feed on insects such mosquitos and midges along the Columbia River. Once planned to be destroyed, the clearwell has been preserved as a bat haven.
Decades ago, the F Reactor area was home to rats, cats, dogs, cows, sheep, goats, pigs and even alligators. At times, up to 1,000 animals were kept there as an experimental animal farm.
Research was conducted from 1945 to the 1970s to study the potential effects of radiation exposure to humans. That included a large-scale test of sheep that ate tainted feed to determine the health effects of radioactive iodine released from Hanford stacks during fuel processing.
Alligators kept there escaped at least once in the early 1960s. Most were recovered, but a 33-inch alligator later was caught by an angler downriver near Ringold. Hanford officials confiscated it.
As part of environmental cleanup, Hanford workers removed 40,000 tons of carcasses, manure and other waste from the burial trenches near the former animal farms. That included a railroad tanker car packed with putrid animal carcasses in plastic bags.
Only minimal radioactive contamination was found in the carcasses dug up from the former farm.
Much of the environmental cleanup of F Reactor, however, was similar to that being done to date at other reactor areas.
Waste was buried during construction and operation of the reactor that included high-pressure cylinders, stray pieces of irradiated fuel and irradiated metal.
Former contractor Bechtel Hanford began cleanup of waste sites in the F Reactor area in 2005, and Washington Closure continued the work, with a total of 1.5 million tons of contaminated material hauled away. Much of it went to a lined landfill for low-level radioactive and chemical waste in central Hanford.
The debris came from 112 facilities that were torn down and 88 waste sites that were dug up, including sites where contaminated water from cooling the reactor was disposed of in the soil.
In one area, workers had to dig down to groundwater, about 47 feet deep, to remove soil contaminated with spilled chromium. Sodium dichromate was added as a corrosion inhibitor to river water used to cool F Reactor.
However, less chromium contamination was found near F Reactor than at some of the other reactor sites at Hanford. What has reached groundwater is not of regulatory concern and will be allowed to dissipate naturally, McCormick said.
Groundwater monitoring will continue at F Reactor. In addition, some planting remains to be done over back-filled soil at dig sites. That will be performed in the fall, said Rob Cantwell, Washington Closure director of field remediation.
"Once we've done revegetation, nature takes over and it is pretty quick how it recovers," McCormick said.
w Annette Cary: 582-1533; email@example.com