An installation for the conversion of uranium hexafluoride (UF.sub.6) to uranium dioxide (UO.sub.2) comprises a hydrolysis reactor (4) for the conversion of UF.sub.6 into uranium oxyfluoride powder (UO.sub.2F.sub.2), a pyrohydrolysis furnace (6) for converting the UO.sub.2F.sub.2 powder supplied by the reactor (4) into UO.sub.2 powder, a supply device (8) comprising reagent injection ducts (10) for the injection of UF.sub.6, water vapor or H.sub.2, and a control system (16) designed to control the supply device (8) so as to supply at least one of the reagent injection ducts (10) with a neutral gas during a shut-down or start-up phase of the conversion installation.

A separation apparatus for separating a supply of high-level nuclear waste (HLW), where the HL nuclear waste is separated into high-mass and low-mass portions. The high-and-low mass portions of the HLW have respective atomic masses that are above and below an atomic mass cut-off point of the separation apparatus. The separation apparatus includes first and second ICP torches that are respectively mounted to and within an apparatus housing. The apparatus housing defines a cylindrical separation chamber and includes first and second magnetic elements which generate a magnetic field along the length of the separation chamber, and a plurality concentric ring electrodes which generate an electric field that is perpendicular to, and which crosses the magnetic field. The supply of HLW is subject to a mass separation process within the separation chamber using the set of crossed electric and magnetic fields.

A single integrated system for recycling used nuclear fuel (UNF) emerging from a reactor has a decladding vessel separating fuel pellets from nuclear fuel rods via oxidation to produce U.sub.3O.sub.8. A fluorination vessel is coupled to the decladding vessel to remove hexafluorides from the U.sub.3O.sub.8 produced by the decladding vessel. An electrowinning vessel is coupled to the fluorination vessel removing plutonium and actinides via electrowinning.

A single integrated system for recycling used nuclear fuel (UNF) emerging from a reactor has a decladding vessel separating fuel pellets from nuclear fuel rods via oxidation to produce U.sub.3O.sub.8. A fluorination vessel is coupled to the decladding vessel to remove hexafluorides from the U.sub.3O.sub.8 produced by the decladding vessel. An electrowinning vessel is coupled to the fluorination vessel removing plutonium and actinides via electrowinning.

The-use of carbamides as extractants for fully or partially separating uranium(VI) from plutonium(IV) in an aqueous solution obtained by dissolving a spent nuclear fuel in nitric acid, by method of liquid-liquid extraction, without carrying out any reduction of the plutonium(IV) to plutonium(III). The invention also relates to new carbamides. Uses are the processing of spent nuclear fuels based on uranium (especially uranium oxides—UOX) or uranium and plutonium (especially mixed uranium and plutonium oxides—MOX).

The-use of carbamides as extractants for fully or partially separating uranium(VI) from plutonium(IV) in an aqueous solution obtained by dissolving a spent nuclear fuel in nitric acid, by method of liquid-liquid extraction, without carrying out any reduction of the plutonium(IV) to plutonium(III). The invention also relates to new carbamides. Uses are the processing of spent nuclear fuels based on uranium (especially uranium oxides—UOX) or uranium and plutonium (especially mixed uranium and plutonium oxides—MOX).

Methods and systems for separation of thorium from uranium and their decay products are provided. The method comprises combining a nuclear fuel feedstock comprising thorium and uranium with a first acid to form a first solution. The first solution is contacted an ion exchange resin that is selective for thorium or uranium. The thorium or uranium is at least partially removed from the first solution by binding the thorium or uranium to the ion exchange resin thereby forming a second solution. The second solution is combined with oxalic acid to precipitate uranium or thorium from the second solution to form a precipitate. The precipitate is separated from the second solution.

A single integrated system for recycling used nuclear fuel (UNF) emerging from a reactor has a decladding vessel separating fuel pellets from nuclear fuel rods via oxidation to produce U.sub.3O.sub.8. A fluorination vessel is coupled to the decladding vessel to remove hexafluorides from the U.sub.3O.sub.8 produced by the decladding vessel. An electrowinning vessel is coupled to the fluorination vessel removing plutonium and actinides via electrowinning.

A single integrated system for recycling used nuclear fuel (UNF) emerging from a reactor has a decladding vessel separating fuel pellets from nuclear fuel rods via oxidation to produce U.sub.3O.sub.8. A fluorination vessel is coupled to the decladding vessel to remove hexafluorides from the U.sub.3O.sub.8 produced by the decladding vessel. An electrowinning vessel is coupled to the fluorination vessel removing plutonium and actinides via electrowinning.

The present invention relates to a method for recovering plutonium from spent radioactive fuel. In one embodiment, the method comprises steps of extracting tetravalent plutonium from an aqueous solution of the spent radioactive fuel using a first organic solvent comprising tributyl phosphate; reducing tetravalent plutonium to trivalent plutonium by adding to an organic phase a second organic solvent comprising dimethylhydroxylamine; and stripping plutonium into the aqueous phase for recycling by adding an aqueous dilute acid solution into an organic phase. The method can significantly improve the efficiency of recovering plutonium from spent radioactive fuel compared with HAN stripping, and at the same time, can avoid the problems resulting from U(IV) reduction and extraction.