US researchers claim nuclear waste advance

New York -- Scientists at Penn State University and the Savannah River National Laboratory claim to have developed a new way to process liquid wastes into solid form for safe disposal.

The process employs temperatures of 90°C or below to solidify and stabilise high alkali, low-activity radioactive waste. The resulting form, which the researchers term ‘hydroceramic,’ is strong, durable and can encapsulate minor radioactive components within its zeolitic structure.

The research teams are working with the US Department of Energy (DOE), which is storing around 80 million gallons of radioactive waste in underground tanks at two sites in Richland, Washington and Aiken, South Carolina.

The researchers’ main focus is on supernate -- a type of waste that coexists with a small amount of highly radioactive sludge settled at the bottom of the tanks. Supernate makes up most of the volume, but contains only a fraction of the radioactivity.

While the DOE is to vitrify the highly radioactive sludge, the researchers say the new technology offer a viable alternative for treating the supernate waste. The teams are also developing an equivalent hydroceramic concrete to fill empty waste tanks at both sites.