Equilibrium Core Optimization of Composite Moderators in Pebble Bed High-Temperature Gas-Cooled Microreactors

As both industry and government move toward meeting their decarbonization goals, nuclear power is increasingly being considered due to its legacy of providing clean and reliable power. Pebble bed (PB) high-temperature gas-cooled reactors (HTGRs) are a generation-IV reactor design being considered because of their past operational experience, intrinsic safety features, and online refueling capabilities. PB-HTGRs are conventionally moderated with graphite, but in the high-temperature and high-fluence environment of PB-HTGRs, graphite undergoes several undesirable property changes that limit the lifetime of the graphite components in the reactor.