Optimization study on neutron/γ radiation-protective clothing materials with computational human phantoms

The applications of nuclear science and technology in both production and daily life are becoming increasingly widespread. Radiation shielding, as a critical component, ensures environmental safety and protects human health. In this study, 20 shielding schemes were designed using ethylene-propylene diene monomer as the base material. These schemes incorporated various proportions of boron carbide and gadolinium oxide as neutron-absorbing components and tungsten as the gamma-shielding component. Based on the Chinese reference adult male (CRAM) voxel model and using an anterior-posterior (AP) irradiation setup, the Monte Carlo method was employed to calculate 28 organ/tissue doses and effective dose reductions from neutron and gamma radiation across the 20 material compositions. Each case was evaluated at three different thicknesses-1, 3, and 5 mm-with Monte Carlo calculation errors controlled within 1%. Results indicated that, for any composite shielding material, the 5-mm thickness provided optimal protection. When an unmoderated and unthermalized 252Cf neutron source was used, effective dose reductions ranged from 32.60% to 38.75% compared to the unshielded case. With a monoenergetic neutron source at 1 keV, the reduction range was between 57.62% and 69.42%. The trend in changes for different composite shielding materials under neutron sources at different energy levels is consistent. When 137Cs served as the gamma source, effective dose reductions ranged from 7.96% to 20.97%, demonstrating that the composite materials offer substantial protection for both neutron and gamma radiation. Additionally, it was found that organs partially exposed outside the shielding material experienced a slight increase in dose due to neutron scattering. In practical applications, full-body protection should be implemented to mitigate this issue.