Abstract: According to an embodiment, a nuclear fuel material recovery method of recovering a nuclear fuel material containing thorium metal by reprocessing an oxide of a nuclear fuel material containing thorium oxide in a spent fuel is provided. The method has: a first electrolytic reduction step of electrolytically reducing thorium oxide in a first molten salt of alkaline-earth metal halide; a first reduction product washing step of washing a reduction product; and a main electrolytic separation step of separating the reduction product. The first molten salt further contains alkali metal halide, and contains at least one out of a group consisting of calcium chloride, magnesium chloride, calcium fluoride and magnesium fluoride. The method may further has a second electrolytic reduction step of electrolytically reducing uranium oxide, plutonium oxide, and minor actinoid oxide in a second molten salt of alkali metal halide.

Abstract: A spent nuclear fuel is reprocessed by dissolving a spent nuclear fuel in an aqueous nitric acid solution and separating and recovering nuclides contained in the resulting fuel solution by solvent extraction. A spent nuclear fuel reprocessing method includes: an electrolytic valence adjustment step in which nuclides contained in the fuel solution is electrolytically reduced without removing fission products or minor actinides until valence of plutonium is at a level at which solvent extraction efficiency is low by using the valence of plutonium contained in the fuel solution as a parameter; and a nuclide separation step in which, by using an extraction solvent which extracts uranium contained in the fuel solution, uranium is distributed from the fuel solution subjected to the electrolytic valence adjustment step to the extraction solvent.

Abstract: According to an embodiment, a nuclear fuel material recovery method of recovering a nuclear fuel material containing thorium metal by reprocessing an oxide of a nuclear fuel material containing thorium oxide in a spent fuel is provided. The method has: a first electrolytic reduction step of electrolytically reducing thorium oxide in a first molten salt of alkaline-earth metal halide; a first reduction product washing step of washing a reduction product; and a main electrolytic separation step of separating the reduction product. The first molten salt further contains alkali metal halide, and contains at least one out of a group consisting of calcium chloride, magnesium chloride, calcium fluoride and magnesium fluoride. The method may further has a second electrolytic reduction step of electrolytically reducing uranium oxide, plutonium oxide, and minor actinoid oxide in a second molten salt of alkali metal halide.

Abstract: According to one embodiment, a method of separating and recovering metals whereby a mixture containing at least a first metal and a second metal, the second metal having a higher standard electrode potential than that of the first metal, is connected to an anode in a molten salt, and the first metal and the second metal are precipitated on a cathode in the molten salt by electrolysis, the method of separating and recovering metals comprising: a detection step of detecting a concentration change in each of a first metal ion and a second metal ion in the molten salt by a concentration change detection unit; a first electrolysis step of electrolyzing the first metal; a first recovery step of recovering a precipitated substance according to a detection in which a concentration decrease of the first metal ion, which is predefined in the concentration change detection unit, is detected in the detection step; a second electrolysis step of electrolyzing the second metal; and a second recovery step of recovering a pre

Abstract: An object of the present invention is to provide a method of producing metal zirconium, the method having a fewer steps and a smaller amount of secondary wastes generated, wherein the metal zirconium is obtained from a zirconium compound containing hafnium. A method of producing metal zirconium according to the present invention includes: a separation step of separating a hafnium oxychloride from a first substance containing a zirconium oxychloride and a hafnium oxychloride to obtain a second substance having a higher content of the zirconium oxychloride; a calcination step of calcining the second substance to obtain a third substance containing at least any of a zirconium oxychloride and a zirconium oxide; and a direct reduction step of holding the third substance in a molten salt with the third substance brought into contact with a cathode and applying a voltage between the cathode and an anode to directly reduce the third substance to obtain metal zirconium.

Abstract: A corium processing method includes a dissolution step of feeding the corium into a first molten salt and dissolving uranium oxide and plutonium oxide contained in an oxide solid from the corium; a nuclear fuel recovery step of recovering the uranium oxide and the plutonium oxide from the first molten salt; a metal recovery step of feeding the corium into a second molten salt and separating and recovering metal Fe and metal Zr by molten salt electrolysis; and a solidification step of solidifying and recovering residues of the corium.

Abstract: According to one embodiment, a method of separating and recovering metals whereby a mixture containing at least a first metal and a second metal, the second metal having a higher standard electrode potential than that of the first metal, is connected to an anode in a molten salt, and the first metal and the second metal are precipitated on a cathode in the molten salt by electrolysis, the method of separating and recovering metals comprising: a detection step of detecting a concentration change in each of a first metal ion and a second metal ion in the molten salt by a concentration change detection unit; a first electrolysis step of electrolyzing the first metal; a first recovery step of recovering a precipitated substance according to a detection in which a concentration decrease of the first metal ion, which is predefined in the concentration change detection unit, is detected in the detection step; a second electrolysis step of electrolyzing the second metal; and a second recovery step of recovering a pre

Abstract: According to one embodiment, a process for producing rare metals includes the steps of: recovering a first-residue solution through a primary target metal extracted by leaching a mineral resource; extracting a perrhenic acid ion contained in the first-residue solution with at least one of an anion exchange resin and a first-organic solvent; back extracting the perrhenic acid ion contained in the anion exchange resin or the first-organic solvent to a first-eluant; and electrolyzing the back extracted first-eluant to collect a rhenium at a cathode.

Abstract: According to one embodiment, a process for producing rare metals includes the steps of: recovering a first-residue solution through a primary target metal extracted by leaching a mineral resource; extracting a perrhenic acid ion contained in the first-residue solution with at least one of an anion exchange resin and a first-organic solvent; back extracting the perrhenic acid ion contained in the anion exchange resin or the first-organic solvent to a first-eluant; and electrolyzing the back extracted first-eluant to collect a rhenium at a cathode.

Abstract: According to one embodiment, a process for producing rare metals includes the steps of: electrolyzing an electrolytic solution to extract a Re oxide at a cathode; recovering the Re oxide, and electrolyzing the Re oxide in a molten salt electrolyte to extract metallic Re; recovering a Nd containing residue solution; treating the Nd containing residue solution to produce Nd oxide; electrolyzing the Nd oxide in a molten salt electrolyte to extract metallic Nd; recovering a Dy containing residue solution; treating the Dy containing residue solution to produce Dy oxide; and electrolyzing the Dy oxide in a molten salt electrolyte to extract metallic Dy.

Abstract: An object of the present invention is to provide a method of producing metal zirconium, the method having a fewer steps and a smaller amount of secondary wastes generated, wherein the metal zirconium is obtained from a zirconium compound containing hafnium. A method of producing metal zirconium according to the present invention includes: a separation step of separating a hafnium oxychloride from a first substance containing a zirconium oxychloride and a hafnium oxychloride to obtain a second substance having a higher content of the zirconium oxychloride; a calcination step of calcining the second substance to obtain a third substance containing at least any of a zirconium oxychloride and a zirconium oxide; and a direct reduction step of holding the third substance in a molten salt with the third substance brought into contact with a cathode and applying a voltage between the cathode and an anode to directly reduce the third substance to obtain metal zirconium.

Abstract: According to one embodiment, a process for producing rare metals includes the steps of: electrolyzing an electrolytic solution to extract a Re oxide at a cathode; recovering the Re oxide, and electrolyzing the Re oxide in a molten salt electrolyte to extract metallic Re; recovering a Nd containing residue solution; treating the Nd containing residue solution to produce Nd oxide; electrolyzing the Nd oxide in a molten salt electrolyte to extract metallic Nd; recovering a Dy containing residue solution; treating the Dy containing residue solution to produce Dy oxide; and electrolyzing the Dy oxide in a molten salt electrolyte to extract metallic Dy.

Abstract: A spent nuclear fuel is reprocessed by dissolving a spent nuclear fuel in an aqueous nitric acid solution and separating and recovering nuclides contained in the resulting fuel solution by solvent extraction. A spent nuclear fuel reprocessing method includes: an electrolytic valence adjustment step in which nuclides contained in the fuel solution is electrolytically reduced without removing fission products or minor actinides until valence of plutonium is at a level at which solvent extraction efficiency is low by using the valence of plutonium contained in the fuel solution as a parameter; and a nuclide separation step in which, by using an extraction solvent which extracts uranium contained in the fuel solution, uranium is distributed from the fuel solution subjected to the electrolytic valence adjustment step to the extraction solvent.

Abstract: A spent fuel reprocessing method has a dissolution step of dissolving the spent fuel in nitric acid solution, an electrolysis/valence adjustment step of reducing Pu to trivalent, maintaining the pentavalent of Np, a uranium extraction step of collecting UO2 by bringing the fuel into contact with organic solvent and extracting hexavalent U by means of an extraction agent, an oxalic acid precipitation step of causing MA and the fissure products remaining in the nitric acid solution to precipitate together as oxalic acid precipitate, a chlorination step of converting the oxalic acid precipitate into chlorides by adding hydrochloric acid to the oxalic acid precipitate, a dehydration step of synthetically producing anhydrous chlorides by dehydrating the chlorides in a flow of Ar gas, and a molten salt electrolysis step of dissolving the anhydrous chlorides into molten salt and collecting U, Pu and MA at the cathode by electrolysis.