[en] 1. Specific character analysis of ligand and extractant for uranium decontamination: The solubility of extractants and that of nitric acid-ligand complexes were measured under supercritical carbon dioxide. 2. Process mechanism analysis for uranium decontamination: Distribution coefficient of uranium according to amounts of ligand and concentration of nitric acid were measured under supercritical carbon dioxide. Dissolution of uranium by TBP-HNO₃ and formation of microemulsion by proline were identified under supercritical carbon dioxide. 3. Unit and demonstration experiment for extraction of uranium from aqueous solution: Uranium extracted by chelating ligand from aqueous solution under supercritical carbon dioxide. 4. Unit and demonstration experiment for extraction of uranium from soil: Uranium extracted by extractants from soil under supercritical carbon dioxide. The increased extraction efficiencies of uranium from soil by synergic effect using TBOD and sub-ligands were resulted under supercritical carbon dioxide. 5. Design for general idea of commercial soil contaminated uranium decontamination facility: The 50mL scaled equipment for uranium decontamination was designed and manufactured based on the result of basis experiment. The 300L scaled soil contaminated uranium decontamination facility was designed based on operation condition of the 50mL scaled equipment for uranium decontamination