A process to separate the sodium from radioactive aqueous effluents resulting from spent fuels reprocessing

This invention concerns the separation of sodium from radioactive aqueous effluents resulting from spent fuels reprocessing. The sodium separation is carried out with the use of charged porous membranes methods and of nano-filtration. Membranes are formed by a polymer layer as poly-aramids, sulfonated poly-sulfone or ionomer containing fluorine. The tangential filtration technology limits the accumulation phenomenon of the retained species at the membrane surface and is then used preferentially. In order to obtain the wished retention rates, the pH value of the aqueous effluent, the temperature, the pressure and the flow rates have to be adjusted. The membrane retention rate for the radioactive elements can be improved by the complexation with the use of chelating agents of one or several elements present in the effluent. Radioactive effluents without sodium can be then stored in vitreous matrices. (O.M.). 4 refs., 26 figs., 4 tabs