Temperature distribution in nuclear fuel rod, burn-up (BU), possibility of nuclear fuel rejuvenation and breeding parameters are investigated for different coolants under various first wall loads (Pw = 2, 5 and 7 MW m (-2)) in a deuterium-tritium driven fusion-fission reactor system, fueled with mixed UO2-ThO2 fuel. The fuel mixture is considered to be mixed with various mixture fractions.