In this study, the fluids were composed with increased mole fractions of a mixture of molten salt: heavy metals 99-95 % Li20Sn80-1 - 5 % SFG-Pu, 99 - 95 % Li20Sn80-1 - 5 % SFG-PuF4, 99 - 95 % Li20Sn80-1 - 5 % SFG-PuO2. In this study, the effect on conversion of each isotope (Pu238-242) in spent fuel grade plutonium by (n,gamma) reactions was investigated in liquid first wall, blanket and shield zones of the designed hybrid reactor system. Beryllium (Be) is the neutron multiplier by (n,2n) reactions. The Be zone used was 3 cm thick. 9Cr2WVT, a ferritic steel, is used as structural material. Three-dimensional nucleonic calculations were performed by using the most recent versions of the MCNPX-2.7.0 Monte Carlo code and the nuclear data library ENDF/B-VII.0.