Investigation of BeO as a reflector for the low power research reactor

Calculations of the fuel burnup, core excess reactivity, and the reactivity worths of the top beryllium shim plates for two reflector types (beryllium and beryllium oxide (BeO)) in the Miniature Neutron Source Reactor (MNSR) have been presented in this paper using the GETERA and MCNP4C codes. The results showed that the reactor infinity multiplication factors were 1.7030 and 1.6824, the core unadjusted excess reactivities were 31.9 and 5.0 mk, and the reactivity worths of the top beryllium shim plates were 22 and 19 mk for the BeO and Be reflectors respectively. Finally, using the beryllium oxide instead of the existing Be reflector in the MNSR reactor increased the core excess reactivity and reactor operation time.