Crystallization behavior of uranium and plutonium in nitric acid solution

Yano, Kimihiko ; Shibata, Atsuhiro  ; Nomura, Kazunori  ; Koizumi, Tsutomu; Koyama, Tomozo

U crystallization is effective to minimize solvent extraction process equipment by separating U from dissolver solution of spent fuel. In order to establish crystallization process for FBR MOX fuel, Pu behavior needs to be investigated with mixed U and Pu solution. Pu valence influence on the decontamination factor (DF) of Pu to U in crystal. Pu(IV) was not crystallized with U and DF was about 30. Although Pu(VI) dose not solely crystallized, it was co-crystallized with U and DF of Pu to U in crystal was about 1.3. The effect of Pu(IV) concentration on crystallization yield of U is small. It had a tendency to decrease crystallization yield of U by that Pu(VI) exists, compared with that calculated by solubility of U in U-HNO-HO system.