Abstract: Mixed low-energy neutron and γ-ray radiations may exist in the working environment of the spent fuel reprocessing plants, which threatens the health of staff. In this work, Monte Carlo simulations based on Geant4 software is applied to assist the design of composite materials, i.e., tungsten/boron fibers in the polymer substrate containing boron and bismuth, for shielding such mixed radiations by simulating the effects of various material parameters. The results show that this tungsten-boron composite material has an excellent shielding effect for both neutron and γ-ray radiations. It can be proved that the vertical arrangement of fibers has better shielding effect than parallel arrangement, since the distribution of transmission beam became more uniform when the fibers were arranged vertically. Moreover, the shielding effectiveness of this material can be further enhanced by adding bismuth into the polymer substrate. These findings can be expected to provide guidance not only for radiation protection suits, but also other relevant protective gears used in the radiation environment, such as reprocessing plants.

Key words: mixed neutron and γ-ray radiations, radiation shielding, Geant4, tungsten/boron fibers