Mesoscale simulations of thermal transport in w-uo₂ cermet fuel for nuclear thermal propulsion

Nuclear thermal propulsion (NTP) provides constant power for long space missions, which is a tremendous benefit over chemical rockets. Therefore, a lot of effort in investigating different fuel concepts and geometries has been invested. For applications involving NTP or nuclear power, it is very important that the heat generated by the fissile nuclei can be quickly transferred to the coolant. It is then essential that the fuel has a high thermal conductivity so that minimum stored energy is left inside the fuel. In this project, the thermal performance of a WUO₂ CERMET fuel was assessed. The effective thermal conductivity was calculated at the mesoscale for a 3-dimensional microstructure using the MOOSE framework. Then, the results were compared with published literature and analytical solutions. The thermal conductivity calculated using MOOSE was approximately 20% lower than that proposed by the Bruggeman model. The temperature profile in 7, 19 and 61-channel fuel concepts were analyzed using the MOOSE framework. The 61-channel concept had the best performance due to a better ratio of cooling surface area to fuel volume.