Conceptual design and neutronic analysis of a megawatt-level vehicular microreactor based on TRISO fuel particles and S-CO2 direct power generation

With global warming, the demand for diversified energy sources has increased significantly. Transportable microreactors are important potential supplements to the global power market and are a promising development direction. This paper describes a 5 MW integrated long-life S-CO2 cooled vehicular microreactor (VMR) design based on tristructural isotropic (TRISO) fuel particles that aims to provide electricity for industrial power facilities, remote mines, and remote mountainous areas that are not connected to central power grids. First, to facilitate transportation, flexible deployment, and simplified operation and maintenance requirements, the VMR core and auxiliary system were designed to be reasonably small and as simple as possible. Second, the TRISO fuel particles used in the proposed VMR offer excellent properties, such as high inherent security and nonproliferation, which are vital for reactors in remote areas. In addition, a long core lifetime was achieved using the compact core design and enhanced fuel loading capacity, which is challenging when using TRISO as fuel. Finally, to make the VMR economically competitive in terms of improved neutron performance and fuel efficiency compared to similar designs, large-size TRISO particles and tube-in-duct fuel assembly were utilized and different core configurations were schemed and simulated to obtain the design that best satisfied the proposed criteria. The lifetime and burnup in the final optimized VMR were satisfactory at 21 years and 43.9 MWd/kgU, respectively, with an adequate shutdown margin and excellent safety parameters to ensure safe operation.