For the recovery of lanthanides and actinides such as europium and uranium from spent nuclear oxide fuel, the sulfide process which consists of three steps such as, 1) voloxidation, 2) selective sulfurization and 3) selective dissolution, has been proposed. The new process has some advantages for the recovery of nuclear materials from spent fuel with more effective and convenient methods comparing with conventional wet processes. Lanthanide oxides were selectively sulfurized by the use of CS2 at temperature lower than 673 K, while actinide oxides such as UO2 remain as oxide. After the sulfurization, lanthanides were found to dissolve into nitric acid. The sulfurization and dissolution behavior of plutonium was studied by the use of chemical analogue, CeO2 and plutonium tracer. From the results, the separation of lanthanides and actinides could be achieved by the sulfide method, i.e. selective sulfurization and dissolution. The applicability of the sulfide process to the spent nuclear fuel reprocessing was also discussed.
