Investigation of lead oxide particulate formation and dissolution in lead-bismuth eutectic rod-bundle flow channels

Precise oxygen control in liquid lead-bismuth eutectic is essential for the safe and efficient operation of lead-cooled fast reactors. Insufficient oxygen accelerates the corrosion of structural materials, while excessive oxygen leads to the formation of solid PbO particles, which pose risks of flow blockages and degraded heat transfer. This study employs a coupled computational fluid dynamic–population balance model to simulate the nucleation, growth, and dissolution of PbO particles within a wire-wrapped fuel assembly during heating. The impact of key operational and geometric parameters—including Reynolds number, heat flux, and sub-channel position—on the spatiotemporal evolution of oxygen concentration and PbO particle characteristics are systematically investigated. The results demonstrate that lower Reynolds numbers and higher heat fluxes substantially accelerate the onset and progression of PbO nucleation and dissolution. Simulated oxide particles predominantly fall within the range of 10 -9 to 10 -8 meters. These findings offer new insights for optimizing oxygen control strategies and mitigating impurity-driven risks in liquid lead-bismuth eutectic cooled reactor systems.