Hanford's U Canyon prepped for demolition

Work has started to grout in the cells where radioactive waste was processed at the bottom of U Canyon at Hanford, preparing the massive building for demolition.

By the time workers are done, they will have poured 20,000 cubic yards of cementlike grout, enough material to fill six Olympic-size swimming pools.

Below the deck of the plant are 40 cells designed to chemically process radioactive material. Now they are filled with equipment, pieces of piping and other material from the plant that have been lowered by crane and fitted in like puzzle pieces.

Two small test pours of grout in April showed that the material could fill any open spaces and encapsulate equipment and debris as planned, clearing the way for full-scale grouting by CH2M Hill Plateau Remediation Group and its Tri-Cities subcontractors, AGEC and Central Pre-Mix.

A batch plant has been built outside U Canyon to produce the grout that will be needed. The material will be inserted through 100 eight-inch holes up to 17 feet long drilled through the exterior walls of the building, the cell covers and elsewhere.

The building is called a canyon because of its approximately 800-foot-long interior, with high walls and no windows.

"The sheer size of the building has been the main driver of our planning all along," said Dave Chojnacki, CH2M Hill project manager, in a statement.

U Plant was built during World War II, but two other canyons were able to keep up with processing irradiated fuel to remove plutonium for the nation's nuclear weapons program without bringing the new plant online. However, in 1952, it was converted to recover uranium from waste generated by other processing plants and was operated for five years.

After the below-deck cells of U Can-yon are grouted in, plans call for collapsing the walls and building an earthen barrier over the demolished building to keep out water.

The Department of Energy and CH2M Hill expect the canyon to be ready for demolition by fall, but money for the work is not budgeted until 2015 when most of the environmental cleanup along the Columbia River is completed.

Work is being done now with federal economic stimulus money.

U Canyon will be the first processing plant in the DOE complex to be prepared for demolition and could serve as a model for other plants, including the four additional chemical processing plants at Hanford.

This story was originally published June 14, 2011 at 12:00 AM with the headline "Hanford's U Canyon prepped for demolition ."