RICHLAND, Wash.-The Department of Energy's River Corridor contractor, Washington Closure Hanford, has begun cleanup of highly radioactive underground silos at Hanford's 118-K-1 Burial Ground. The burial ground is near Hanford's K East Reactor area in southeastern Washington state.
The burial ground is about 16 acres in size and a half-mile from the Columbia River. The original configuration of the burial ground included 16 trenches and 11 silos. It operated from 1955-73 and accepted wastes from the K East, K West and N reactors.
The six silos located in Trench I of the 118-K-1 Burial Ground are corrugated metal pipes 10 feet in diameter and 25 feet deep.
"We know that most of the highly radioactive waste is located at the bottom of the silos," said Scott Parnell, project manager for the 118-K-1 Burial Ground. "We'll start by removing the first 10 feet of debris from within the silos using an excavator equipped with a special bucket called a clamshell. Once the first 10 feet is removed, we'll work from the lower hazard to the higher hazard silos."
Parnell said their approach is to take each step slowly, carefully and deliberately to ensure the protection of workers and the environment at every stage of cleanup.
Some of the things they expect to find in the silos include: remnants of the reactors safety systems, used nuclear fuel, tritium targets and cobalt irradiators with extremely high dose radiation rates.
"To put it in perspective, if it is there (cobalt irradiators) it would be the most radioactive piece of material we would have brought out of a burial ground in a hundred areas we remediate to date," says Parnell
Work on the silos is expected to take three months to complete. Work for the entire site is to be completed by spring of 2012.
Washington Closure removed 130,000 tons of contaminated material from the site between May 2006-June 2008. Since work resumed in January 2010, workers have dug up 140,000 tons of contaminated material, such as lead, soft wastes, reactor process tubes, spacers and highly radioactive piping and other reactor equipment and hardware.
The cost of the project is $9.4 million dollars.