Columbia-based Duratek Inc. said yesterday that it has signed two subcontracts, worth $110.7 million, with Bechtel National Inc. to design and test a waste-treatment plant in Washington state that will convert radioactive waste to glass.

One of the Department of Energy's largest and most complex environmental cleanup jobs, the Hanford Waste Treatment Plant project will treat more than 53 million gallons of highly radioactive tank waste, which was a byproduct of plutonium produced for America's nuclear weapons during World War II and the Cold War.

Using vitrification technology, which converts waste to glass pellets, Duratek will help Bechtel develop and test a pilot-scale plant and then design a full-scale system for the Hanford site. Duratek has been working on the Hanford project since 1996, but the new multi-year agreements mean that it will no longer have to negotiate subcontracts every year.

The plant is expected to begin operations in 2006 or 2007.

"This ensures our role there until 2006," said Diane R. Brown, director of investor relations at Duratek. "It also positions our company to go after the bid to run the operations of the facility after that. We hope to be a part of this project for a very, very long time."

The first subcontract with San Francisco-based Bechtel, which is the primary contractor on the project, is valued at $86.7 million. It involves research, development and testing of the pilot-scale melters and glass development formulation for the plants. The second subcontract, worth $24 million, will involve designing and completing the full-scale waste treatment system.

Once the plant is completed, it will treat waste stored in 177 underground tanks. According to Bechtel, at least 67 of the tanks are known to have leaked as much as a million gallons of waste into the surrounding soil and groundwater.

Shares of Duratek closed yesterday at $6.85, up 19 cents.