Multiphysics framework development and energy conversion analysis for a space nuclear power system

Nuclear energy systems present a compelling solution for deep-space exploration by offering high energy density, long operational life, and independence from solar illumination. Among various space nuclear power concepts, the heat pipe reactor (HPR) is particularly advantageous due to its compact structure, low mass, high energy density, inherent safety, and modularity. This study develops a comprehensive multiphysics coupling framework based on COMSOL, enabling integrated neutronic, thermal, mechanical, and system-level electrical analyses under both steady-state and transient conditions. The framework has been validated against existing experimental data and simulation results. Subsequently, the platform is applied to a space-based HPR system equipped with a static thermoelectric generator (TEG), facilitating a detailed analysis of the energy conversion performance from fission heat to electrical power. Various operational scenarios are simulated, including nominal operation, reactivity insertion, heat sink temperature fluctuations, and heat pipe failure events. Simulation results demonstrate that the system maintains stable operation during transients and transitions to new steady-state conditions via inherent negative feedback mechanisms. In all simulated scenarios, the fuel and heat pipe wall temperatures remain within safety limits, confirming the system's robust safety characteristics. Furthermore, the framework enables precise evaluation of energy conversion efficiency and system-level electrical output behavior in response to temperature field variations and reactor dynamics. These results underscore the effectiveness of the proposed framework as a predictive tool for both safety assessment and the performance optimization of space nuclear power systems.