The extraction and recycling of fissile isotopes as well as their separation from the fission products was studied. order to use it in a fuel cycle, the extracted fuel must be allowed to decay for 3 years, which is sufficient to decrease the radiation background 1000-fold and lower the temperature at which water-extraction methods can be used. The equilibrium elemental composition of the fuel to be reprocessed approximately corresponds to the content of the elements in spent mixed fuel of fast reactors, with the exception of the elements of the carrying salt. The precipitated oxides are separated from the carrying salts by filtration, dissolved in 3M/liter nitric acid, and subjected to extraction reprocessing using 30% tributyl phosphate in dodecane. The uranium transitions into the organic phase; neodymium remains in the water phase. After washing, the uranium is re-extracted by a diluted solution of nitric acid and after denitration converted into UF4, which is returned into the fuel composition. Upon coprecipitation from the uranium and neodymium melt with stoichiometric deficit of Na₂O, the neodymium precipitates approximately twice as efficiently as uranium, which suggests the possibility of a new fuel-cycle closure scheme for a fast molten-salt reactor based on LiF–NaF–KF. After adjustment, the fuel composition purified by removal of a large part of the lanthanides is returned into the reactor, the precipitate of lanthanides with part of the uranium and plutonium is allowed to decay and after complete separation of uranium and plutonium is also returned into the reactor.