Verification of SuperMC for MNSRs core analysis: The case of Ghana Research Reactor-I

The commercial type Miniature Neutron Source Reactors (MNSRs) have relatively uncomplicated structures. They use highly enriched uranium (HEU) as fuel, light water as moderator, coolant and shield, and beryllium as reflector. However, efficient and accurate modeling, calculation and analysis are necessary for safety evaluation of operational processes, assessment of routine operations' safety and for planned modifications to ensure optimum utilization. In this work, the neutronics characteristics of MNSR-GHARR-1 (Miniature Neutron Source Reactor-Ghana Research Reactor-1) have been extensively studied with SuperMC code, with an intention to verify SuperMC for MNSRs' analysis. In respect of the later intent, the germaneness of SuperMC for modeling and calculation of MNSRs-GHARR-1's core analysis has been duly verified. In all calculations, ENDF/B-VI.6 nuclear data library was used, with S (α β) scattering feature applied on specified compound materials for thermal scattering treatment. The criticality results (keff, shutdown margin, control rod worth and core excess reactivity) compared with reference results, showed very close agreement. In addition, neutron distribution characteristics curves for axial irradiation channels (inner and outer) have been shown to be consistent with expected MNSR's neutronics and physics characteristics. We have also demonstrated through simulation of different control rod positions that, the control rod fluctuations do not affect neutron distribution in the experimental zones, but only have significant effect within its immediate environment. In an uncharacteristic fashion of other codes, the convenient visualization features of SuperMC for post processing of output data, has been applied for the analysis of neutron evolution within MNSR core.