Monte Carlo simulation of neutron shielding performance of iron spherical shell

Neutron Shielding with different energy is one of the important issues in radiation safety. To investigate the neutron shielding performance of iron spherical shell, this paper built a simple physical model of iron spherical shell; the neutron transport processes in iron spherical shell with different thicknesses were numerically simulated by using Monte Carlo method. For isotropic neutron source with energy ranging from 0.1 keV to 14 MeV, the numbers of leakage neutrons and gamma rays from iron spherical shell with different thicknesses has been obtained. The simulation results show that both the energy of neutron source and the thickness of iron spherical shell shield have a significant influence on number of leakage neutrons and gamma rays. For iron spherical shell shield, the number of leakage neutrons decreases with the increase of thickness of iron spherical shell when the normalized number of leakage neutrons is less than 1 (i.e. when the number of neutrons absorbed by iron is few), but increases with the increase of thickness of iron spherical shell when the normalized number of leakage neutrons is greater than 1 (i.e. when the reaction of (n, 2n) occurs in neutron transportation process). For neutron source with energy of 2 MeV, the normalized number of leakage neutrons is less than 1. The normalized number of leakage gamma rays keeps the trend from increase to reduction with the increase of thickness of iron spherical shell shield; the ratio of number of leakage neutrons to leakage gamma rays decreases with the increase of thickness of iron spherical shell shield for a certain range of thickness. (paper)