Open pool–type nuclear research reactors are essential for various applications, including material testing, radioisotope production, and fundamental nuclear research. Ensuring a stable hot water layer within these reactors is vital for operational safety and to minimize radiation release. This research aims to optimize flow dynamics and temperature distribution within a typical open pool research reactor. Using computational fluid dynamics analysis, four different geometry configurations are investigated by varying the coolant distributors and hot water headers to determine the most effective configuration. The velocity field and temperature distribution within the reactor are analyzed for each configuration.

This study indicates that using a mesh coolant distributor with a three-layered hole configuration in the hot water header leads to a 32.18% reduction in average velocities and a 57.21% decrease in turbulence generation in the hot water section, as compared to the conventional T-shaped coolant distributor with a single-layered hole configuration. The Richardson number, a parameter for measuring thermal stratification in the hot water section, is approximately 20, indicating the stability of the hot water layer. The average turbulent Reynolds number is 4120, meaning flow stability in the reactor pool. These characteristics led to the successful attainment of a hot water layer with a thickness of 2.11 m and an average temperature of 48.35°C.