Development of a fast thermal-hydraulic model to simulate heat and fluid flow in MNSR

•A TH model is developed as the first step in developing a micro-simulator for the MNSR.•The model relies on the integral form of conservation equations of fluid dynamics.•The model well predicts the normal operation of MNSR at different power levels. Extending a reliable and fast thermal–hydraulic model is the first stage in developing a micro-simulator for a miniature neutron research reactor (MNSR) with training and educational objectives. The framework of the TH model, which comprises an explicit finite difference formulation for solving coupled hydraulic and thermal equations with variable water properties, is explored in this study. The hydraulic section uses the integral form of the momentum equation to relate the mass flow rate variation to buoyancy and friction forces. The thermal part of the model relies on the integral form of the energy equation for different elements of the reactor including fuel, core, reflector, tank, chimney, and pool. The model's results are compared to reactor operation data and available correlations for various reactor powers. According to the comparison, the model's output matches the trend of experimental data for all power in both short and long time periods and predicts the eventual temperature rise of the core with an error of less than 5%. The performance of the model in other operational conditions is also evaluated. The model's performance in different operational circumstances is also assessed, and the results suggest that reducing the reactor's initial temperature would enhance the core's temperature rise.