More Hanford vitrification tests finished

YAKIMA – Scientists have completed another round of tests on a process that would turn nuclear waste stored in underground tanks at the Hanford nuclear site into glass for long-term disposal.

About 53 million gallons of highly radioactive waste from World War II and Cold War-era plutonium production sit in 177 aging underground tanks at Hanford, less than 10 miles from the Columbia River.

Plans call for using a process called vitrification to turn the high-level waste into glass logs for long-term disposal in a nuclear waste repository.

Construction already is under way on a plant to treat the high-level waste.

But the plant was not designed to treat all the less-radioactive waste also found in the tanks, and researchers have been studying a similar process called bulk vitrification to treat that material.

The highly radioactive waste would be filtered from the lower-level waste as it flowed into the vitrification plant.

Bulk vitrification requires electric currents to be passed between electrodes in a mixture of soil and tank waste. The aim is for the soil to then capture the waste as it melts into glass.

Using about two gallons of liquid waste from one of the Hanford tanks – the largest quantity of actual tank waste to be used in the bulk vitrification testing to date – scientists completed an engineering-scale test the week of Oct. 11.

CH2M Hill Hanford Group, the contractor hired to handle tank waste cleanup, termed the test a successful “melt,” resulting in a 220-pound slab of radioactive glass.

Detailed tests on the glass remain to be completed to confirm that the mixture meets standards for long-term disposal, said Rick Raymond, director of supplemental treatment for CH2M Hill.

“It’s not a done deal, but it looks very promising,” Raymond said Wednesday. “We need to collect more information before any decision can be made.”

The next step would be a full-scale test of the treatment process. Such a test will provide a solid technical foundation for evaluating the viability of the technology, said Roy Schepens, manager of the U.S. Department of Energy’s Office of River Protection, which manages tank waste cleanup.

The Energy Department has applied for a permit to build and operate a pilot test facility to treat as much as 200,000 gallons of low-level waste.

Public comment already has been accepted on the proposal, but the state Department of Ecology has not yet issued the permit.

For 40 years, the Hanford reservation made plutonium for the nation’s nuclear weapons arsenal. Today, work there centers on a $50 billion to $60 billion cleanup, to be finished by 2035.

Much of the cleanup involves retrieving and treating the tank waste, composed of radioactive liquid, sludge and saltcake. Most critical was the liquid waste in 149 tanks that had a single-wall construction, making them more susceptible to leaks as they aged.