A key material engineering challenge for the spherical tokamak reactor is the neutron shielding in the central column. Tungsten boride ceramics are a primary candidate material, due to tungsten’s effective gamma attenuation and boron’s neutron absorption capabilities. However, the effect of radiation damage on tungsten boride is yet to be examined. Under high energy neutron flux, boron will produce extensive helium and lithium as the activation products due to nuclear reaction. The shield will also experience significant displacement damage causing vacancy clusters.
In this study, helium is deposited via ion beam to mimic such combination of damage and inert gas production. Irradiations are being carried out using in-situ TEM at the Microscope and Ion Accelerator for Materials Investigations (MIAMI) beamline. Additionally, the Dalton Cambrian Facility (DCF) is employed for bulk irradiation, with the aim of ex-situ characterization of material properties. Fully dense tungsten boride samples produced by hot-pressing of powders will be irradiated at various temperatures up to 700°C to evaluate the effect of temperature on defect evolution. This information will be used to inform the integrity of the material in service, including the acceptable operational temperature window of the material and its estimated lifetime.