Vitrifying Nuclear Waste Could Reduce Volume by 90 Percent

By vitrifying plutonium-contaminated waste with the ore refinery byproduct slag, the volume of nuclear waste could be reduced by 90 percent, according to a researcher from University of Sheffield's engineering department.

Blast-furnace slag, a granular byproduct of the ore-smelting process, can be used to vitrify, or turn into glass, plutonium-contaminated waste from nuclear sites, including the Fukushima nuclear campus in Japan, according to professor Neil Hyatt, who tested the process with cerium, an element that behaves like plutonium, but is safe enough to conduct tests upon.

Plutonium-contaminated waste can include a variety of objects and accessories found at nuclear sites, including filters, used personal protective equipment, and decommissioning waste such as metals and masonry. The gross volume of all these contaminated waste products can be staggering, Hyatt said.

"The overall volume of plutonium-contaminated wastes from operations and decommissioning in the UK could be upwards of 31,000 cubic meters, enough to fill the clock tower of Big Ben seven times over," Hyatt said. "Our process would reduce this waste volume to fit neatly within the confines of just one Big Ben tower."

Currently, the most commonly used method of disposal for non-compactable, plutonium-contaminated waste products is to entomb them in cement, a practice that generally increases the overall volume of the waste, Hyatt said.

"If we can reduce the volume of waste that eventually needs to be stored and buried underground, we can reduce the costs considerably. At the same time, our process can stabilize the plutonium in a more corrosion resistant material, so this should improve the safety case and public acceptability of geological disposal," he said.

"Cerium is known to behave in similar ways to plutonium so provides a good, but safe, way to develop techniques like this," Hyatt said in a news release. "Our method produces a robust and stable final product, because the thermal treatment destroys all plastics and organic material. This is an advantage because it is difficult to predict with certainty how the degradation of plastic and organic materials affects the movement of plutonium underground."

Hyatt is currently working on optimizing the vitrification process to support full-scale demonstration.