Preliminary Multi-physics Coupled Simulation of Small Helium-Xenon Cooled Mobile Nuclear Reactor

Abstract For the prediction of the internal physical process of SIMONS (Small Innovative helium-xenon cooled MObile Nuclear power Systems), this research created a coupled three-dimensional high-fidelity calculation platform of the neutronics/ thermo-elasticity analysis called FEMAS (FEM based Multi-physics Analysis Software for Nuclear Reactor). This platform allows for the multi-physics coupling calculations of neutron diffusion/ transport, thermal diffusion, and thermal elasticity. It is based on the open-source Monte Carlo code OpenMC and the open-source finite element codes Dealii and Fenics. In this paper, a simplified SIMONS reactor core is analyzed using the coupling platform. The results demonstrate that the coupling platform is capable of accurately predicting the effective multiplication factor change curve, power and temperature distribution, and thermal expansion phenomenon of SIMONS. With 240 kW of thermal power, the local temperature difference of the whole reactor is 390.1 K, and thermal stress-related deformation occurs at a rate of 2.4%. The reactivity feedback caused by the monolith’s heating and thermal expansion is 30.5 pcm. Leveraging the high-precision computing hardware, this platform can assess the core performance to ensure that the core design satisfies the design criteria of ultra-long life and inherent safety.