HANFORD -- A massive door that will shield workers from radiation was installed at the Hanford vitrification plant this week.
The 102-ton door was lowered through the roof of the Pretreatment Facility, the largest building at the plant, and placed on top of an adjoining 85-ton door that was installed last month.
"This installation was particularly complex due to the size, shape and layout of these two massive doors," Ty Troutman, Bechtel National area project manager for the facility, said in a statement. "It required extensive planning by our skilled craft and engineers."
The carbon steel doors come together to form an upside-down L-shape. The upper, heavier door is oriented horizontally and will be the largest in any vit plant building. It measures 52 feet wide and 15 feet tall.
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The lower door is oriented vertically and measures 15 feet wide and 27 feet tall. Both are 10 inches thick, including a stainless steel liner.
They were manufactured by Oregon Iron Works Inc. in Portland.
"Setting these doors, as well as the overhead crane last month, marks a transition in the Pretreatment Facility from a civil construction focus to mechanical installations," Wahed Abdul, of the Department of Energy, said in a statement. "This will enable us to complete construction in 2016 and reach operations by 2019."
The doors will be controlled using three giant motorized drive screws -- two in the upper and one in the lower door. The screws are 20 feet long and about 3 inches in diameter. The upper door will slide open and closed vertically, and the lower door will slide horizontally.
The doors separate the canyon-like center of the Pretreatment Facility, known as the "hot cell," from a maintenance area that will be used to service an overhead crane and remote-handling equipment. When operational, the hot cell will be used for the waste radioactive separations process and will be highly radioactive and inaccessible by humans. All hot cell maintenance will be performed using the crane and remote-handling equipment.
A third shield door separates the maintenance area from the rest of the Pretreatment Facility. The two doors installed recently and the third door will never be open at the same time.
Construction of the building is 34 percent complete.