Separation of fission products from irradiated uranium dioxide in fused nitrate systems

The separation of fission products from irradiated UO₂ in fused nitrate systems was studied by the following procedure: Dissolution of UO₂ in fused NH₄NO₃; adsorption of fission products on glass powder; fused salt chromatography with γ-Al₂O₃; evaporation from fused nitrates; and precipitation of U-compound (probably alkali uranate, M₂U₂O₇) in a fused LiNO₃-KNO₃ mixture. Radiochemically pure Zr-Nb was selectively separated from the fused NH₄NO₃ melt by adsorption. Ru and I were completely evaporated from fused LiNO₃-KNO₃ mixture at above 280℃ and from fused NH₄NO₃at above 240℃, respectively. By means of chromatography with a γ-Al₂O₃ column, Zr-Nb and rare earths were completely separated from U in fused NH₄NO₃ or fused NH₄NO₃-LiNO₃ medium at 150° to 180℃, and further, Cs, Ba and Ru were also expected to be separable from U under suitable condition. When the U-compound was precipitated in fused LiNO₃-KNO₃ at 350℃, Cs, Sr, Ba and Ru were fairly well separated from U. (author)