The optimization of photon-neutron target and electron beam energy for the subcritical small modular reactor driven with electron accelerator via MCNPX code

Abstract

Small modular reactors and accelerator driven subcritical reactors have many potentials, which have attracted the attention of many researchers. In this study, the sub-criticality of a small portable reactor is proposed to increase reactor safety and widespread use in different areas and the feasibility study of subcritical operation of a mobile power generator to produce economic power has been conducted. The MCNPX 2.6 code was used to simulate the photon-neutron source and the Holos subcritical core. The optimization of this cylindrical target was done so that it would have the highest neutron leakage and an acceptable deposited heat for easy heat removal from the target. Other parameters such as the optimized electron beam, the radial and axial flux distributions for thermal, epi-thermal and fast neutrons, heat and dose distributions in the reactor core have been calculated. According to the computational data, the most flux of the leaked neutrons from the target was obtained for energy 2 MeV and the maximum flux of leaked photons from the target was calculated for the photon energy of less than 10 MeV, which have the maximum probability of neutron and photon fissions. Most of the leaked particles from the target are photons and calculations have shown that part of the output power of the subcritical core is due to (γ,fission) reaction in fuel assemblies of the Holos subcritical core. It was shown that a small portable subcritical core driven with a 100 MeV, 100 mA electron accelerator produces total thermal power of 7 MW.