Separation of uranium from fission products

A simple procedure has been developed for separating U from F.P. and neutron-irradiated Th. The separation is performed with tri-n-butyl phosphate in a system of dodecane-mixture of sulfuric acid and aluminium nitrate. Uranium dioxide was irradiated with 20 MeV bremsstrahlung, which produced both 237U and F.P. The target was dissolved in dilute nitric acid and U was extracted into the organic phase of the above mentioned system. Finally, U in the organic phase was back-extracted into an aqueous phase. The γ-ray spectrum and decay curve of the separated U fraction show no radioactive nuclides other than U isotopes and its decay products. This method can also be applied to the preliminary separation of 238U from neutron- irradiated Th. The distribution ratios (Kd) for U, Th and some other elements in the extraction system are also given.