Mass Optimization of a Supercritical CO₂ Brayton Cycle Power Conversion System for a Mars Surface Fission Power Reactor

In the National Aeronautics and Space Administration (NASA) Design Reference Architecture 5.0 (DRA 5.0), fission surface power systems (FSPS) are described as “enabling for the human exploration of Mars.” This study investigates the design of a power conversion system (PCS) based on supercritical carbon dioxide (sCO₂) Brayton configurations for a growing Martian colony. Various configurations utilizing regeneration, intercooling (IC), and reheating are analyzed. A model to estimate the mass of the PCS is developed and used to obtain a realistic mass-optimized configuration. This mass model is conservative, being based on simple concentric tube counterflow heat exchangers and published data regarding turbomachinery masses. For load following and redundancy purposes, the FSPS consists of three 333 kW_e reactors and PCS to provide a total of 1 MW_e for 15 years. The optimal configuration is a sCO₂ Brayton cycle with 60% regeneration and two stages of intercooling. The majority of the analyses are performed in matlab, with certain data provided by a comsol multiphysics model of part of a low-enriched uranium (LEU) ceramic metallic (CERMET) reactor core.