Process for reprocessing a spent nuclear fuel and of preparing a mixed uranium-plutonium oxide

A process for reprocessing a spent nuclear fuel comprising uranium, plutonium, fission products, americium and curium and for, preparing a mixed uranium-plutonium oxide, comprising at least:

• a) separating the uranium and plutonium from the fission products, the americium and the curium that are present in a aqueous nitric acid solution that results from dissolving the spent nuclear fuel in nitric acid, a) comprising coextracting uranium in oxidation state (VI), and plutonium in oxidation state (IV), from the aqueous nitric acid solution by bringing the solution into contact with a water-immiscible solvent phase comprising at least one extractant in an organic diluent;
• b) partitioning the uranium and plutonium coextracted in a) into two aqueous phases, a first aqueous phase comprising plutonium and uranium, and a second aqueous phase comprising uranium but not containing plutonium;
• c) purifying the plutonium and uranium present in the first aqueous phase obtained after b) from the fission products also found in the first aqueous phase;
• and
• d) coconverting the plutonium and uranium that are present in the aqueous phase obtained after c) into a mixed uranium-plutonium oxide.