YAKIMA – Three down, 174 to go.
Workers at Hanford Nuclear Reservation have completed the removal of radioactive and chemical waste from a third underground tank less than 10 miles from the Columbia River. The milestone marks the second time this year that workers completed a project to remove solid waste from a tank. The first tank was emptied of solid waste in 2003.
“The tanks are the most important cleanup project at Hanford. There’s no greater need,” said Sheryl Hutchison, spokeswoman for the state Department of Ecology, which regulates the U.S. Department of Energy’s cleanup operations at the site. “So every one they get emptied is a big step forward.”
For 40 years, the Hanford reservation made plutonium for the nation’s nuclear weapons arsenal. Today, work there centers on a $50 billion to $60 billion cleanup, to be finished by 2035.
Much of the cleanup involves treating 53 million gallons of highly radioactive waste that has been stewing in 177 aging underground tanks. Most critical is the waste in 149 tanks that have a single-wall construction, making them more susceptible to leaks as they age.
The single-shell tanks, built from the 1940s through the ‘60s, were designed to last about 20 years. An estimated 67 of them leaked about 1 million gallons of radioactive brew into the soil, contaminating the aquifer and threatening the river.
Last year, the last liquids were pumped from all the single-shell tanks into newer, double-walled tanks. However, the tough job of removing sludge or hardened salt cake at their bottom remained.
In 2003, workers used a sluicing method to remove sludge from the first tank, C-106. The method involved adding acid to dissolved sludge and then washing away waste with water. For tank C-203, completed in March, workers inserted a vacuum hose into the tank to suck up sludge containing radioactive cesium and strontium. The process took nine months.
The vacuum procedure was repeated for tank C-202, a 55,000-gallon tank built in 1944 to store waste from the production of nuclear materials for the top-secret Manhattan Project. Removal of solid waste from the tank was completed last week, six weeks after the project began, said Ryan Dodd, CH2M Hill vice president of closure operations for one of the tank farms. CH2M Hill is the contractor hired to handle the tank farm cleanup.
“From nine months to six weeks is a major accomplishment for us, and really demonstrates our learning in the process and our operation getting much more efficient at how to operate this vacuum system,” Dodd said Tuesday when cleanup of the third tank was announced.
Cleanup at the Hanford site is governed by the Tri-Party Agreement, the cleanup pact signed by the Energy Department, state Ecology Department and the U.S. Environmental Protection Agency.
Subscribe to the Coronavirus newsletter
Get the day’s latest Coronavirus news delivered to your inbox by subscribing to our newsletter.