Numerical Investigation on Heat Transfer Features of Gas-Cooled Open Lattice Reactor in Normal Operations

Abstract The gas-cooled reactor combined with Brayton cycle energy conversion system has been investigated with the application potential to meet the requirement of large power nuclear reactor systems in deep space explorations. Conceptual core design configured in the open lattice has attracted extensive attention due to the compact structure, and its heat transfer features need further investigation, including conduction, convection, and radiation. Many studies on thermal-hydraulic characteristics of similar structure reactors such as Pressurized Water Reactor (PWR) and Sodium Cooled Fast Reactor (SFR) have been carried out. However, different operating conditions bring the distinct heat transfer features. Referring to Prometheus program, this paper analyses the heat transfer features of gas-cooled open lattice reactor by numerical simulations. The computational fluid dynamic tool (ANSYS Fluent) is mainly used to investigate the effect of circumferential rod heat conduction, thermal radiation among fuel rods, and gas flow distribution. The results show that contributions of conduction, convection and radiation to the total reactor core heat transfer should be taken into account. The maximum temperature on the walls can be lower by increasing the rod thermal conductivity, enhancing the thermal radiation among fuel rods, and increasing the gas flow of inner core. This study will help to develop the system code for the thermal-hydraulic design and safety analysis of gas-cooled open lattice reactors.