The depletion analysis of the Nigerian research reactor fuel with 19.75% enriched UO2 have been performed using the VENTURE PC code. The matrix exponential method was selected in this work to perform the depletion analysis. The volume fraction of the materials in this mixture was calculated and multiplied by their respective atom densities to obtain the effective atom density of the nuclide in the water, Aluminium mix region of the fuel cell model. The plot of the variation of k infinity versus hydrogen to Uranium ratio was generated using Matlab programming language for processing of the computer code result. This shows that as the ratio of hydrogen to uranium in the core of the reactor is increased, the reactivity also increases by gradually increasing the fuel cell radii till it gets to the peak of 0.6193. Any further increment in the radius of the fuel cell radii, the reactivity of the reactor decreases as the hydrogen to uranium ratio increases.