Los Alamos National Laboratory researchers have performed a critical experiment using high-assay low-enriched uranium (HALEU) TRISO fuel. It is the nation’s first criticality safety experiment using HALEU fuel in more than 20 years. On November 21, LANL announced the work of its Deimos team, which earlier this year carried out an experiment at the National Criticality Experiments Research Center (NCERC), operated by LANL at the Nevada National Security Site.