Hanford

World’s largest radioactive waste melter assembled at Hanford

Bechtel National subcontractors install refractory brick in 2014 in a Low Activity Waste Facility melter at the Hanford nuclear reservation’s vitrification plant. The facility’s first melter has been assembled, meeting a construction milestone.
Bechtel National subcontractors install refractory brick in 2014 in a Low Activity Waste Facility melter at the Hanford nuclear reservation’s vitrification plant. The facility’s first melter has been assembled, meeting a construction milestone. Courtesy Bechtel National

Hanford workers have finished assembling what will be the world’s largest radioactive waste melter when it begins operating at the nuclear reservation’s vitrification plant.

“This is a large, technically complex piece of equipment,” said Bill Hamel, the Department of Energy project director for the plant. “I really can’t emphasize that enough. This is a significant accomplishment for the project.”

Contractor Bechtel National earned $4.275 million, as outlined in its contract, for getting the first melter that will be used at the plant’s Low Activity Waste Facility assembled.

The facility will have a second melter, and Bechtel may earn another $4.275 million by finishing its assembly in September.

DOE has set a goal to start processing low-activity radioactive waste at the plant as soon as 2022, turning it into a stable glass form for disposal.

The glass melters are at the heart of the process, Hamel said.

30 tons amount of glass the Low Activity Waste Facility could produce daily

Concentrated low-activity radioactive waste will be mixed with glass-forming materials, including silica, and then heated to 2,100 degrees Fahrenheit in the two melters. The mixture will be poured into stainless steel containers to harden for permanent disposal at Hanford.

The low-activity waste, which makes up the majority of the 56 million gallons now held in underground tanks at Hanford, is left from the past production of plutonium for the nation’s nuclear weapons program during World War II and the Cold War.

Work on the melters started in about 2002 with the initial design, followed by construction of a prototype and a particular focus on the refractory, or liner, that will contain the molten glass mixture.

The glass mixture will be so hot that metal would melt, so the refractory was assembled from specially manufactured interlocking bricks measured in thousandths of inches. When the melter gets hot, the refractory will expand and form a seal.

The refractory will be surrounded with a metal shell with a bolt system to keep it from expanding or contracting too much, then a cooling jacket and another shell.

We are supremely confident this facility is going to safely process the waste that currently threatens the environment here at Hanford.

Peggy McCullough, Bechtel National project director

The melter also has a system of lids, with one serving as a radiation shield and the other sealing the melter to allow a ventilation system to keep radioactive gases contained.

Each of the Low Activity Waste Facility’s melters will weigh 300 tons and measure 20 by 30 feet and 16 feet high,

Together they will produce 30 tons of glass a day, which is 10 times the capacity of a melter that is vitrifying radioactive waste at DOE’s Savannah River, S.C., site.

Assembling the melter, with only some final hookups to be made when the electricity is turned on, prepares the melter to be heated up.

“There was a tremendous amount of work that went into that — engineering, procurement, construction, nuclear safety — and we are supremely confident this facility is going to safely process the waste that currently threatens the environment here at Hanford,” said Peggy McCullough, Bechtel National project director.

The plant, which is expected to cost more than $17 billion, also will have a second facility to glassify the portion of the tank waste that is high-level radioactive waste.

Technical issues have delayed work on parts of the plant that will handle high-level radioactive waste, but the plant is expected to be fully operational to meet a court-enforced deadline in 2036.

Annette Cary: 509-582-1533, @HanfordNews

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