Salawu A., Balogun G. I., Jonah S. A. and Zakari Y. I.
A number of cell models of the heterogeneous regions in a Miniature Neutron Source Reactor (MNSR) as well as a full core computational model have been developed and a cross section library has been generated for the Nigeria Research Reactor-1 (NIRR-1), a version of the MNSR, manufactured by China Institute of Atomic Energy. Because of the low density of U238 in the present HEU system, the resonance shielding effect does not produce any significant reduction in the absorption rate in the three regions of the energy dependent U238 cross section generated for NIRR-1 system. The same is true for the resonance plus spatial self shielding effect on the U238 absorption cross section except at a very low thermal energy of about 0.005eV. Various plots of multigroup neutron flux as a function of energy or lethargy has shown that the NIRR-1 behaves as expected of a typical thermal reactor system. The position of the reference NIRR-1 on the plot of k-infinity as a function of hydrogen to uranium ratio predicted an over moderated system for the reactor with a hydrogen to uranium ratio of about 180.
