A more efficient formula for vitrifying radioactive waste has been developed by a team of researchers at Pacific Northwest National Laboratory and the Savannah River Technology Centre.
A more efficient formula for vitrifying radioactive waste has been developed by a team of researchers at Pacific Northwest National Laboratory (PNNL) and the Savannah River Technology Centre (SRTC).
By allowing more waste to be incorporated into each batch of glass, this new glass formula may significantly reduce the price tag attached to vitrifying waste, which is an integral part of cleaning up nuclear waste in the US.
Scientists at PNNL and SRTC studied the details of the glass-melting process and applied glass property models to develop a new frit (the glass-forming material used in vitrification). This frit is expected to yield significantly higher melter throughput and higher waste loading (ratio of waste to frit), while maintaining adequate quality of the glass product.
The Defence Waste Processing Facility at the Savannah River Site is the largest waste vitrification plant in the world. There, highly radioactive waste is currently mixed with Frit 200, heated until they are molten, and poured into canisters.
The canisters can then be disposed of in a federal geologic repository. Frit 200 reportedly produced excellent glass but wasn’t optimised for quickly processing Savannah River’s high-level waste sludge, meaning it took a long time for the waste and frit mixture to melt into glass.
The new PNNL/SRTC formula (Frit 320) showed a melt rate 20% faster than the previous frit in small-scale melter tests. In addition, recent calculations and laboratory tests showed that the Savannah River Site sludge loading in Frit 320 might be significantly higher than in Frit 200, while maintaining all Defence Waste Processing Facility constraints.
According to Savannah River’s Bill Holtzscheiter, Immobilisation Technology Integration Manager for the US Department of Energy’s Tanks Focus Area, the life cycle costs savings will be significant. Each 10 percent improvement in the melt rate will save about $800 million. Each percent waste loading improvement will save about $300 million over the current baseline.