Installation of the two melters for the Low-Activity Waste Facility at the Hanford’ Site’s Waste Treatment Plant has been completed, a key milestone on the project, plant officials announced Wednesday.
“When operational, these melters will be the largest operating vitrification plant melters in the world,” said Bill Hamel, Department of Energy project director for the vit plant, which will convert millions of gallons of chemical and radioactive waste stored at Hanford into a glass form for permanent disposal.
The melters are 10 times larger than the melters being used to treat high-level radioactive waste at DOE’s Savannah River Site in South Carolina, said Peggy McCullough, vitrification plant project director for contract prime Bechtel National.
“With the melters assembled and all major process equipment already installed, our workforce remains on pace toward the construction complete contract milestone of June 2018 for the LAW Facility,” McCullough said. Under Bechtel National’s contract it earned $4.275 million for assembling the first melter this spring and should earn the same for the second melter.
Each melter weighs 300 tons and measures 20 by 30 feet and 16 feet high. Together they will produce 30 tons of glass a day. The melters will heat a mixture of concentrated low-activity radioactive waste and glass-forming material to 2,100 degrees Fahrenheit. The mixture will be poured into steel containers to harden for disposal at Hanford.
Remaining construction at the facility includes installing electrical equipment, hooking up mechanical processes, putting in permanent lighting, and making some small design changes. Some facility startup work has begun, under plans to energize electric, water, mechanical, steam, and chiller services, first at the component level, then the system level, and then facility-wide. Commissioning also must be done before the planned 2022 start of waste treatment at the facility. Facility operations will be tested first with water and then with a waste simulant before the treatment of low-activity radioactive waste begins.
Completing the melters “is a huge milestone,” said Alex Smith, manager of the Washington state Department of Ecology’s Nuclear Waste Program. But much work remains, she said, both to begin operating all the facilities needed to treat low-activity radioactive waste and also to start treating high-level radioactive waste.
Construction stopped in 2012 on parts of the plant that will treat high-level radioactive waste to resolve technical issues. DOE faces a court-ordered deadline to have all facilities at the vit plant, including those handling high-level waste, operating together in 2036.
The fourth of the nine technical issues identified under former Energy Secretary Steven Chu has been resolved with completion of full-scale mixing tests at a Washington State University Tri-Cities laboratory, Hamel said. Testing that started in 2014 confirmed calculations that showed a pulse jet mixing system could keep waste adequately mixed in vessels in the WTP Pretreatment Facility. The pulse jet mixers have no moving parts that would need to be maintained once they are contaminated with waste. They work like a turkey baster, sucking up material and expelling it, to keep waste well mixed and prevent heavy particles from settling to the bottom of the vessel. Adequate mixing helps prevent the slight chance of a criticality or an accumulation of flammable hydrogen. The remaining technical issues are expected to be resolved by the end of the year.
