Burning up radioactive waste

A new process to deal with nuclear waste is being developed at the US department of energy's research facility at Hanford, Washington State, writes David Black.

GeoMelt involves heating the waste to more than 2,000 C, turning it into a glassy, rock-like mass which is 10 times stronger than concrete and impervious to erosion.

The first test of the process was carried out by Amec, the construction and engineering company, as part of a long-term clean-up programme at Hanford, which used to be the main plutonium production site in the US.

Amec has won a $7.6m (£4.5m) contract to test whether its existing bulk vitrification technology could be adapted for radioactive waste disposal.

The process involves ex cavating a pit, filling it with the waste and then inserting high-temperature electrodes (see artist's impression above).

An Amec spokesman said: "The electrodes effectively melt the contaminated soil and waste, destroying all organic contaminants through pyrolysis [chemical decomposition caused by high temperatures] and catalytic reactions, and in the process it permanently immobilises all hazardous inorganic and radioactive contaminants."

Amec's process has already been used for other forms of toxic wastes, including polychlorinated biphenyls (PCBs), dioxins and heavy metals. The process prevents the main hazard of burying such materials - the leaching of toxins into the surrounding soil and ground water.

If the process works on radioactive waste, it could be used to clean up an estimated 4m cubic metres of contaminated material in the UK alone - much of it left over from decommissioned nuclear power stations.

Amec is to carry out two further trials next month. If the process is judged a success, the company said its commercial potential will be "global and enormous".