Time evolution of criticality and burn up grades of the Fixed Bed Nuclear Reactor (FBNR) are investigated using alternative fuels. Neutron transport calculations are performed by using XSDRNPM/SCALE 5 codes. Firstly, the calculations were performed to search the optimum compositions of UO2/Reactor grade-PuO2; UO2/weapon grade-PuO2 and of UO2/MAO(2) that would result in the similar initial value of keff as that of UO2, the original fuel of FBNR. Fuel component has been varied from 1% to 100%. The fuel compositions have been obtained with UO2: (1) 35% RG-Pu (2); 19% WG-Pu O-2; (3) 50% MAO(2). After that, ken burnup and operation time values of the fuels were compared. The temporal variation of the criticality keff and the burn-up values of the reactor have been calculated by full power operation for a period of 18 years. The criticality in compositions of Reactor grade-PuO2/UO2; weapon grade-PuO2/UO2 and MAO(2)/UO2 starts by k(eff) = 1.2742, 1.2726 and 1.2783 for the fuels compositions, respectively. These mixed fuels would allow full power reactor operation for >= 14 years and burn up grade can reach 104,646, 101,990 and 80,798 MW D/T, respectively. On that way, the hazardous nuclear waste product can be transmuted as well as utilized as fuel. (C) 2013 Elsevier Ltd. All rights reserved.