Ground-breaking research on nuclear waste by US scientists has given their South African colleagues working on preventing the pollution of this country's water by the acid-water draining from old mines a new and powerful tool.Scientists at Washington University, in St Louis, have discovered a new method of immobilising - binding as a compound with another substance - uranium in contaminated groundwater.This is likely to lead to more success in rehabilitation efforts at mines.Uranium is a deadly by-product of gold mining.The research was aimed at neutralising uranium in contaminated groundwater at nuclear waste sites in the US.Researchers discovered a new efficient way of using calcium phosphate to react with and immobilise uranium."The solution is to figure out how to send the phosphate to where the uranium is, and where the phosphate can be added where the natural groundwater flow will bring the uranium into contact with it," said lead researcher Daniel Giammar.In their experiments, researchers first determined the exact level of calcium in the contaminated water. They then added the phosphate, which formed calcium phosphate, chemically binding and neutralising the uranium."This method will give us another tool," said Jo Burgess of the Water Research Council's mine water programme...