Mass and Power Estimations of Moderated and Unmoderated HALEU Fueled Heat-Pipe Reactors for Space Applications

Heat-pipe reactors (HPR) are an interesting option for energy production in space due to their passive cooling capability and core design simplicity. To save mass, most relevant designs exploit highly enriched fuel posing proliferation concerns. Its known that the use of Low-Enriched Uranium (LEU) or High-Assay Low-Enriched Uranium (HALEU) make the reactor heavier. However, this provides no information on the power the reactor can produce. The aim of this work is to estimate the core mass and maximum power of HALEU HPR working at zero gravity. Mass has been computed by means of a pseudo-optimization algorithm using OpenMC Monte Carlo code. Different materials combinations h ave been considered for moderator (ZrHx , YHx , Be) and reflector (BeO, MgO, Z r3Si2). Monolith UMo fuel have been considered. The thermal power limitations have been estimated considering materials temperature constraints, heat-pipe (HP) working limits and neutron fluence l imitations. Among these aspects, the HP limits resulted the primary bottleneck for achieving high powers. To meet the needs of space applications high performance HPs are required.