The Department of Energy is making plans for a third system to prepare radioactive waste for treatment, after the initial two systems planned could not meet a court-mandated deadline for the vitrification plant to start glassifying waste.
Hanford officials say work is on track to start limited operations of the $17 billion vitrification plant by a 2023 deadline set under a federal-court enforced consent decree.
But it needs a way to prepare the waste, separating out only the low-activity radioactive waste held in Hanford's underground storage tanks for initial treatment at the plant.
The plant is not required to be fully operational and also treating high-level radioactive waste until 2036.
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A small system that could be set up next to individual waste storage tanks has been proposed as a demonstration project for the preparation of waste to feed to the vitrification plant in its initial years of operation.
DOE has asked for bids for the latest system, but has yet to announce an award.
Hanford has 56 million gallons of radioactive and hazardous chemical waste left from the World War II and Cold War production of plutonium for the nation's nuclear weapons program. It is being held in underground tanks, some of them prone to leaks, until it can be treated for disposal.
DOE wants to start treating low-activity radioactive waste first, which would need to be separated out of the tank waste. It's classified as high-level radioactive waste.
When construction started on the vitrification plant in 2002, the largest building — standing 12 stories high and covering an area larger than a football field — was the Pretreatment Facility.
It is planned to separate waste into low-activity and high-level waste streams for treatment.
But construction stopped on the Pretreatment Facility in 2012 until technical issues related to the high-level waste it will handle. can be addressed.
DOE switched then to a plan to start treating low-activity waste first.
The department began making plans for a smaller, but permanent, facility to be built in the Hanford tank farms to separate out some low-activity waste from waste storage tanks for initial treatment.
In 2014, DOE put the estimated cost of the new facility before design work started at between $243 million and $375 million.
That cost had risen to $800 million by this spring, Ben Harp, deputy manager of the DOE Office of River Protection, told the Hanford Advisory Board.
The facility would not be pretreating waste in time to meet the court-ordered 2023 deadline for the start of waste vitrification, he said.
Now DOE is looking at a third option: a small system it is calling the Tank-Side Cesium Removal system.
It could be placed on a pad by a tank with much of the work done in a structure the size of a land-sea shipping container
The latest system draws on some of the technology used for cleanup following the Fukushima, Japan, nuclear disaster and that has been developed for use at the Savannah River, S.C., nuclear cleanup site, Ben Harp, deputy manager of the DOE Office of River Protection, told the Hanford Advisory Board last month.
The small system could prepare enough low-activity waste to feed the vitrification plant for its ramp-up period through 2025, Harp said.
The tank-side system would use similar technology to the full-scale Pretreatment Facility to remove chemicals from the waste that must be treated as high-level waste.
Low-activity radioactive waste is primarily liquid, but suspended solids and radioactive cesium dissolved in the liquids are designated as high-level radioactive waste and must be removed if the waste is treated as low-activity waste.
The system would filter the liquid to remove solids and use an ion exchange system to remove cesium.
The used ion-exchange columns filled with captured cesium would be stored on pads initially.
The cesium would eventually be sent to a national repository for high level radioactive waste, once the nation has one, but no decision has been made on how the cesium in the columns might be prepared for disposal.
DOE budget documents show that design and permitting activities for the system would start during the current fiscal year and construction in fiscal 2019.
The report for the Senate spending bill covering Hanford for fiscal 2019 says money may be spent to test one tank-side treatment unit, but DOE may not expand use of the system until it reports to Congress.
It must tell the Senate and House appropriations committees how the tank-side system will be integrated with other facilities, how costs compare with other approaches and proposed plans for the cesium it removes.
Annette Cary; 509-582-1533; @HanfordNews