An improved radiochemical separation of uranium and thorium in environmental samples involving peroxide fusion.

A radiochemical procedure for the accurate determination of uranium and thorium using peroxide fusion followed by ion exchange and extraction chromatography is described. The method of extraction of the element from solid samples is the most important factor in the investigation. It is demonstrated, by measuring a number of reference materials, that fusion with Na(2)O(2) ensures a complete destruction of the mineral lattice and greatly improves the determination of the true activity of actinides.