Performance of Gadolinium-Neutron Shielding Layer Formed by Plasma Thermal Spray Method

Plasma thermal spray coating method was applied to prepare a high performance neutron shielding layer for various applications such as nuclear spent fuel transportation and storage containers and experimental research reactors. In this study, layers with various compositions of a gadolinium oxide neutron absorber and a nickel alloy binder on a 304 stainless steels substrate were deposited by the plasma thermal spraying method, and their performance including the neutron shielding ability and the corrosion behavior was evaluated to develop a high performance thermal neutron shield coating layer. In the neutron shielding test results, layers with more than a 450 m thick coating with a 1:3 ratio of gadolinium oxide and nickel alloy binder provided 100% thermal neutron shielding against a neutron beam with energy of 48.4 meV and a wavelength of 0.13 nm. Electrochemical corrosion tests showed that the corrosion potential and corrosion rate of the thermal spray coated layers in the artificial sea water were lower than -0.833 VSHE and slower than 7.12×10-5A/cm2, respectively. Both the neutron shielding and the corrosion resistance tests results suggest that neutron shielding layers with thickness exceeding 450 m formed by the plasma thermal spraying method can be effectively applied as a thermal neutron shielding material for spent fuel transportation and storage containers and experimental nuclear reactors.