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Friday, February 23, 2024
Feb. 23, 2024

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After 20+ years, success at Hanford’s huge nuclear waste treatment plant

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KENNEWICK — The vitrification plant at the Hanford site has hit a new milestone — pouring glass for the first time since construction began 21 years ago.

“This marks another important step in commissioning the plant with test glass as we prepare for immobilizing radioactive and chemical waste in glass for safe disposal,” said Mat Irwin, the Department of Energy assistant manager for the vitrification plant.

So far, the first melter is only being tested with glass forming materials. Testing it with mock, nonradioactive waste and then glassifying real radioactive waste are yet to come.

The plant is being built to turn some of the 56 million gallons of Hanford radioactive waste stored in underground tanks, many of them prone to leaking, into a stable glass form for permanent disposal.

Successfully reaching the stage where it has demonstrated it can successfully operate a melter and begun filling a waste container is a step forward after Bechtel National started its first attempt to make glass just over a year ago.

The initial test heatup of the first melter that will be used to mix waste with molten glass was stopped before it reached 300 degrees when a problem was discovered with the power supply to the melter’s startup heaters. It left an inductor in its electrical system blackened from overheating.

After months of troubleshooting and revisions in melter systems to make sure that the melter would operate safely and efficiently, the melter heatup was started for a second time June 25.

This time the melter reached its planned operating temperature of 2,100 degrees Fahrenheit within a month.

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Then glass beads, or frit, produced in Richland began to be added to the melter until the pool of glass was 31 inches deep.

The melter is planned to remain on continuously now for its planned lifespan of five years.

Glass poured at vitrification plant

On Oct. 26 about 900 pounds of glass was poured into a stainless steel container, located below the melter in a “pour cave,” to fill about 10 percent of the container. A second pour was done on Monday for a total of about 1,500 pounds in the container.

The pour was done by remote operations from a control room at the vit plant, with workers watching on video monitors as a stream of molten glass was released from the melter.

The containers that are being used for the first waste to be treated, which is the least radioactive waste held in underground tanks, are about 4 feet wide by 7.5 feet wide.

The container will continue to be filled as more frit is added to the melter, with different crews for the vitrification plant’s round-the-clock operations getting practice on the procedure for pouring in the coming weeks.

As soon as December another major step at the plant is planned. The second of the two melters at the vitrification plant’s Low Activity Waste Facility will be started up.

Two more melters will immobilize high level radioactive waste at the vitrification plant’s High Level Waste Facility. Its construction has been delayed by technical issues, but it is required by a federal court order to be operating in 2033.

The container now being filled with just glass will be hauled on a specially designed truck and trailer to Chemical Waste Management, an industrial and hazardous waste landfill in Arlington, Ore., for disposal. Several practice runs of the 250-mile round trip route have been made.

In early 2025 the Department of Energy expects to start filling containers with a molten glass mixture that includes low level waste.

Treating radioactive waste

The same truck and trailer plus two more will be used to haul canisters with radioactive waste immobilized in glass to a lined landfill in central Hanford, the Integrated Disposal Facility. Each trailer will be able to carry three canisters.

At full production, the vitrification plant’s Low Activity Waste Facility should be processing about 5,300 gallons of waste per day or producing about 23 tons of glass per day, filling 3.5 containers.

The containers of glassified high-level radioactive waste are required to be sent to a national high-level waste repository for disposal, rather than being disposed of with less radioactive glassified waste at Hanford. A site has not been picked after work stopped on the Yucca Mountain, Nev., repository.

The melters in the Low Activity Waste Facility are about 20-feet-by-30-feet and 15 feet high. Each is nearly five times larger than the 65-ton melter operating at DOE’s Savannah River Site’s Defense Waste Processing Facility in South Carolina.

The Hanford melters use temporary heaters at startup and then a second set of heaters are turned on. These are joule heaters that pass an electrical current through the pool of melted glass.

Bubblers are installed to blow air into the bottom of the melter glass pool to mix the glass and prevent hot spots from forming.

The 586-square-mile Hanford site adjacent to Richland in Eastern Washington was used from World War II through the Cold War to produce almost two-thirds of the plutonium for the nation’s nuclear weapons program.

Chemically separating plutonium from uranium fuel irradiated in Hanford reactors, has left 56 million gallons of radioactive and other chemical waste stored in Hanford underground tanks.

The vitrification plant is planned to treat all the high-level radioactive waste in the tanks and much of the low activity waste. About 90 percent of the waste to be treated is low activity waste.

A decision on how to treat the remainder of the waste has not been made.

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