Effect of Poison and Thermal Hydraulic on Miniature Neutron Source Reactor (MNSR) Parameters

Abstract

Over the years of operation of the Nigeria Miniature Neutron Source Reactor's after installation in 2004, numerous installations and calculations were made for the safety of Nigeria Research Reactor-1 in accordance with project supply agreements and IAEA member states. By using the lattice code WIMS and the core analysis code CITATION to automatically perform each of the following calculations on MNSRs: core excess reactivity, verification of certain safety criteria, and calculation of various temperature coefficients of reactivity, we demonstrate in this work the impact of removing cadmium poison on neutron flux and related parameters. Results obtained before, after and after removal of cadmium poison are: excess core reactivity (3.72, 2.96 and 2.92) mkel temperature coefficient reactivity (−0.0018, −0.0054 and −0.0060) mk/^°C, power coefficient of reactivity (−0.2527, −0.1260 and 0.0575) mk/kW and predicted power of (15.23, 14.65 and 14.99) kW with coolant temperature (12.43, 12.10 and 12.50) ^°C respectively. The result will not only boost the sample handling capabilities of NIRR-1 but will also provide useful data to the MNSR community for upgrading their reactors and specifically ageing management.