This research discusses the neutronic design of a fast reactor core of the GFR type with a thermal power of 500 Mwt based on metallic uranium (U-10% wtZr) fuel with a coolant in the form of S-CO2, and by applying the strategy burnup Modified CANDLE in the preparation of fuel during combustion. Neutronic calculations for fuel cells and reactor cores were carried out using the PIJ and CITATION mo…