Preparation and interface analysis of Gd2O3@W core-shell powders as co-shielding absorbers for neutron and gamma-ray

Gd2O3 is often used as an absorber in nuclear fuel shielding because of its excellent neutron absorption capacity. However, Gd element releases prompt gamma rays when absorbing neutrons, which threatens the safety of personnel and equipment. In this paper, a new absorber, Gd2O3@W core-shell powder, is proposed, which can simultaneously absorb thermal neutrons and prompt gamma rays. Firstly, MCNP5 software was used to explore the influence of tungsten layer thickness on γ-ray attenuation ratio, and the thickness of tungsten layer required to shield prompt γ-ray was obtained. Then, in order to explore an effective tungsten plating method, Gd2O3@W core-shell powders were prepared by three methods : powder coverage sintering, sol-gel method and immersion method. The Gd2O3@W core-shell powders prepared by the above three methods were observed and analyzed by SEM and EDS. The results show that the core-shell powder prepared by immersion method is more uniform and dense. Finally, the composition and shell thickness of the Gd2O3@W core-shell powder prepared by immersion method was further studied. The results show that the W layer thickness is about 200 ∼ 600 nm, and there is a diffusion zone between the shell and the core, resulting in new phases Gd2W2O9 and Gd2WO6. The prepared Gd2O3@W core-shell powder in this paper can be used as a co-absorber of neutron and gamma rays for shielding composites.