NUCLEAR FUEL AND PROSPECTS OF CLOSED FUEL CYCLE. Molten- Salt Reactor(MSR) is a design of an advanced reactor system from the GEN IV family working in thermalor epithermal neutron spectrum and using thorium or transuranium fuel in the form of moltenfluorides. It is based on the experience with the development of the molten-salt reactortechnology in the Oak-Ridge National Laboratory in the United States.The MSR fuel cycle with integrated reprocessing represents one of the potential ways both forsignificant decrease of total amount of radioactive wastes for final deposition and forutilization of nuclear energy for electricity and heat production as effectively as possible.There are two pyrochemical reprocessing techniques studied in NRI Rez plc which areconsidered to be applied both for reprocessing of already existing spent fuel and forpreparation and „on-line“ reprocessing of MSR fuel: (i) the Fluoride Volatility Method(FVM), which performs chemical conversion of spent thermal oxide fuel components intofluorides and their consequent separation by means of their different volatility, thermalstability and chemical affinity to various sorbents; and (ii) electrochemical separation of theactinides (Ans) and fission products (FP), represented mainly by lanthanides (Lns), from eachother by electrolytic deposition method on solid cathode in molten fluoride media.Keywords : Pyrochemical Reprocessing, Spent Nuclear Fuel, Closed Fuel Cycle, MoltenSalt Reactor. R. Tulackova, K. Chuchvalcova-Bimova, M. Precek,M. Marecek and Jan Uhlir;