Monte Carlo simulation of low energy neutron reflection characteristic of Al/B₄C composite material

To systematically analyze the neutron reflection characteristics of boron carbide reinforced with aluminium (Al/B4C) composite material, the neutron shielding calculation model of Al/B4C was established. Monte Carlo method had been used to simulate the low energy neutron transmission and reflection coefficients of Al/B4C composite with different mass content of B4C and different thickness of composite material. The results show that the neutron reflection coefficient of Al/B4C increases rapidly with the increase of composite shielding thickness and then tends to saturate when the shielding thickness increases to a certain value. The neutron saturation reflection coefficient and the corresponding saturation reflection thickness both decreases with the increase of B4C mass content in the composite material. The smaller the interaction cross section of the neutron with the material is, the greater the neutron saturation reflection coefficient of the material is, and the greater the saturation thickness required reaching the saturation reflection. In the energy range of 200 eV-20 keV, in addition to the resonance energy point, the neutron reflection coefficient increases with the increase of the neutron energy. The increase of the neutron reflection coefficient per unit of energy increases firstly and then decreases with the increase of energy. When the B4C mass content in the composite material is at the range of 10%-40%, the 100 eV neutron reflection coefficients are below 10%, and the 10 keV neutron reflection coefficients are above 25%.