Workers have begun installing massive shield doors at the Hanford vitrification plant's Pretreatment Facility.

Four of 12 steel doors have been installed, with the last two weighing 22 tons each. They are 10 feet high, 11 feet wide and eight inches thick to shield workers from radiation.

"The installation of mechanical equipment, such as these shield doors, augments progress being made with concrete and steel in the facility," said Leon Lamm, a Bechtel National project manager, in a statement.

The Waste Treatment Plant, or vitrification plant, is 47 percent complete, with design 76 percent complete and construction 40 percent complete.

The Pretreatment Facility, where radioactive waste from underground tanks will be split into high-level and low-activity waste streams for treatment, is the largest building planned at the vit plant. Its design is 68 percent complete and its construction is 26 percent complete. Its footprint is wider than a football field and about as long as a field and a half.

Over the last two weeks, workers installed shield doors to the drum lidding and cask lidding rooms to allow access for filter maintenance.

At the drum lidding room, waste will be received and packaged in 55-gallon drums using remotely operated equipment. The shield door, installed on the second floor, will protect workers while radioactive material is in the room.

Drums filled with waste will be lowered through a hatch into the cask lidding room to be placed into casks and sealed. The door to the room was installed on the first floor.

Installation of larger shield doors is yet to come. The two largest doors each will weigh about 104 tons. They will be 51 feet wide, 12 feet high and about a foot thick.

When the Pretreatment Facility is completed, it will contain more than 113,000 cubic yards of concrete, nearly 17,000 tons of structural steel and 102 miles of piping. This year the Department of Energy expects placement of structural steel at the Pretreatment Facility to be completed to the 56-foot level. When done, the building will stand about 120 feet high.

Plans for construction of the vit plant this year, which includes work at four large buildings and 20 smaller support buildings, also call for placing 10,000 cubic yards of concrete and installing more than 2,500 tons of structural steel.

The structural steel design of the High Level Waste Facility should be completed this year. It will turn high-level radioactive waste into a stable glass form for disposal. Fabrication of the glass melters for the High Level Waste Facility also should be finished.

Work is continuing to resolve remaining technical issues at the vit plant. Testing has begun at the Pretreatment Engineering Platform. The platform, which covers an area the size of a basketball court in a north Richland building, is an approximately quarter-scale model of some equipment that will be used to separate high level and low activity waste at the vit plant.