Evaluation and optimization of efficiency, mass and economics of megawatt-scale space gas-cooled nuclear reactor system

Space nuclear reactors are pivotal for advancing deep space exploration, with the closed Brayton cycle being the most suitable power conversion technology for megawatt-scale systems. Unlike terrestrial reactors, space systems face unique challenges in achieving high thermal efficiency while minimizing mass and costs to ensure orbital launch feasibility. This study focuses on designing a Space Nuclear Energy Reactor system (SNER), evaluating its thermodynamic performance, mass characteristics, and economic implications. Key parameters such as turbine and compressor inlet temperatures, compressor pressure ratio, and recuperator efficiency were analyzed, revealing interdependence among system efficiency, specific mass, and levelized energy cost. Through multi-objective optimization, the theoretical performance limits of the SNER were established. The optimized configuration, compatible with Chinese and American heavy lift launch vehicles for geostationary transfer orbit (GTO), achieves a thermal efficiency of 40.64%, a specific mass of 11.67 t/MWe, and a levelized energy cost of 0.091 $/kWh. Notably, the radiator accounts for over 44% of the system mass, highlighting its importance in mass reduction efforts. This research provides valuable insights for the conceptual design and optimization of space nuclear reactor systems, offering both theoretical and practical significance for future advancements.