In the operation of a nuclear power plant, it is very important to determine the time
evolution of material composition and radionuclide inventory during the entire operation
of the plant. In the experiments, the Monte Carlo N-Particle eXtended (MCNPX) code was
found to be accurate in predicting the uranium fuel depletion, the plutonium production
and the buildup of most of the fission products in a nuclear reactor. The goal in this
chapter is to analyze the effect of different nuclear fuel grades on the total radioactivity
of the reactor core by employing nuclear burnup calculations for the three different fuels:
mixed oxide fuel (MOX), uranium oxide fuel (UOX) and commercially enriched uranium
(CEU), utilizing simulations with MCNPX code. The calculated results indicate that there
is a buildup of plutonium isotopes for UOX and CEU, whereas there is a decline in the
plutonium radioisotopes for MOX fuel with burnup time. The study of reactor neutronic
parameters showed UOX fuel performs better relative to MOX and CEU. Zircaloy, with
low thermal neutron absorption cross-section and high thermal conductivity, produced
better results for the effective multiplication factor Keff and hence proved to be a much
more effective clad material.