Neutron scattering experiment sheds light on HALEU TRISO nuclear fuel

Researchers at Oak Ridge National Laboratory (ORNL) have, for the first time, used neutron scattering techniques to non-destructively probe the internal chemistry of tristructural isotropic (TRISO) nuclear fuel particles containing high-assay low-enriched uranium (HALEU). Conducted at ORNL’s Spallation Neutron Source using the Spallation Neutron and Pressure Diffractometer (SNAP), the experiment directed a focused neutron beam at unirradiated HALEU TRISO particles. By analyzing how neutrons scattered after interacting with the fuel, scientists gained critical insights into the internal structure and composition of these robust, ceramic- and carbon-coated uranium kernels, which are key to high-temperature gas reactors (HTGRs). The study specifically examined the balance between uranium carbide and uranium oxide within the fuel kernels, an important factor influencing fuel performance. Unlike traditional uranium oxide kernels, uranium carbide-based kernels can absorb oxygen released during fission and convert it into uranium oxide rather than