Spent fuel reprocessing process by selective sulfurization

Sato, Nobuaki*; Sato, Soichi 

For the recovery of nuclear materials from spent oxide fuel, a selective sulfurization method was examined. Sulfurization behavior of uranium and fission products such as rare-earths, was investigated by XRD analysis as well as thermodynamic consideration. The sulfurization behavior of PuO was also investigated by using CeO as a stand-in of PuO. The results are summarized as follows; (1)At voloxidation, a part of UO changed to rare-earth doped UO solid solution in the presence of rare-earths. (2)Rare-earth oxides were selectively sulfurized, while UO was reduced to UO. (3)CeO showed a similar sulfurization behavior to that of UO. (4)The sulfurized rare-earths selectively dissolved into nitric acid, while UO did not. (5)Sulfurization behaviors of other fission products such as Cs, Sr and platinum group were discussed by thermodynamic consideration. (6)Process for recycling nuclear materials as oxides by selective sulfurization was proposed.