New reprocessing method overcoming environmental problems

A new method for nuclear fuel reprocessing has been proposed. This method consists of several processes, all of which are carried out in low acidic solutions at room temperature and the separations are made based on precipitation methods without using organic solvents. Therefore, any potential danger of explosion can be avoided. The dissolution of uranium dioxide UO2 fuel was carried out in dilute HCl and HNO3 solutions in the presence of strong oxidants such as chlorine dioxide ClO2 or ozone. In the latter case Ce3+ was used as a catalyzer. Uranium and transuranium elements are separated by a precipitation method as follows. Since penta or hexa valent ions of these actinides form extremely stable complexes with carbonate ion and the complexes formed are soluble in aqueous solutions at pH 7-9, these actinide ions are separated from precipitated fission products. Under such basic solutions most of transition elements, lanthanides, zirconium and platinum group elements as well as alkaline earth metals are precipitated. The platinum group elements, Ru, Rh and Pd are recovered by using the complex formations of these elements with trichlorostannate(II) [SnCl3]-, which precipitates by the addition of some cations, such as Cs+ or quaternary ammonium ion. It was found that [SnCl3]- acts as an effective precipitant of Cs+. (author)