By replacing a large pump in a radioactive waste storage tank at Hanford, workers moved one step closer toward eventually moving millions of gallons of deadly waste from the tank farm to a glassification facility.

The Department of Energy's Office of River Protection and its tank farm contractor, CH2M Hill Hanford Group, successfully replaced a 50-foot transfer pump in Tank AW-104 last week.

The million-gallon tank is one of the tanks that eventually will serve as a staging point after the glassification plant is built and ready to start accepting the highly radioactive wastes stored at the tank farm.

Replacing the old broken pump was perhaps the most challenging work on a Hanford tank in a decade and was significant because it's a major step toward showing how existing double-shelled tanks and underground transfer lines can be upgraded for future cleanup programs.

DOE previously showed it can move waste across the site in a special pipeline, and last spring CH2M Hill showed it could mix up layers of settled waste at the bottom of the underground tanks.

The replacement pump is part of a system for transferring waste through the staging tanks to the glassification plant.

Replacing the pump in Tank AW-104 is part of $1.4 billion in upgrades to prepare the tank farm to transfer approximately 53 million gallons of highly radioactive and hazardous wastes stored at Hanford's 177 underground tanks to the glassification plant.

The waste is mostly stored in 149 old leak-prone single-shell tanks, 67 of which are suspected of leaking more than 1 million gallons of radioactive liquids.

The goals is to move all the waste into 228 of the safer double-shell tanks for eventual conversion to glass logs.

In the immediate future, the newly working pump means some can be transferred from the underground tanks to an evaporation facility, reducing overall volume.

The successful pump replacement comes on the heels of the announcement that DOE has awarded a lucrative contract to the team of Bechtel National Inc. and Washington Group International to continue development of the glassification facility.

DOE fired its original contractor after costs mushroomed to $15.2 billion, in part because of the way that contract was structured.

The plan is to start treating waste by 2007.