Study on flow distribution characteristics of pool-type research reactor

The core of a specific pool-type research reactor utilizes multiple closed plate-type fuel assemblies. Non-uniform coolant flow distribution among these assemblies can lead to localized overheating, posing a safety risk. This study investigates the flow distribution characteristics of the reactor core using a combined approach of theoretical modeling and Computational Fluid Dynamics (CFD) simulation, validated by full-scale experiments. The key findings are: (1) The results from the proposed methodology show a deviation of less than 2% from the experimental data, demonstrating high accuracy. (2) Both analytical and experimental results confirm a uniform flow distribution across different core assemblies, with flow distribution factors ranging from 0.97 to 1.02, thereby meeting the core thermal-hydraulic safety requirements. (3) The reactor retains a 1.82% design margin in bypass flow, which facilitates future target design and enhances operational economics. (4) The flow distribution factors stabilize once the experimental flow rate exceeds 70% of the nominal operating flow rate, indicating that the core has reached a hydraulically stable state.