Comprehensive analysis of oxygen mass transfer and impurity dynamics in oxygen-controlled ELSY lead-cooled reactors

In lead-cooled fast reactors, precise oxygen control is critical for mitigating corrosion, maintaining protective oxide layers, enhancing heat transfer, and reducing impurity deposition. However, achieving consistent oxygen management is challenging due to the high cost and limited availability of sensitive sensors, along with difficulties in monitoring oxygen distribution in pool-type reactors. Existing studies often oversimplify oxygen dynamics, neglecting the impacts of temperature gradients and cyclic flows on reactor-wide oxygen behavior and corrosion processes. This study refines traditional models by incorporating corrosion mechanisms and experimental data to analyze oxygen interactions with iron oxide nucleation in oxygen-controlled environments. Using Computational Fluid Dynamics (CFD), the distribution of oxygen and corrosion products is examined under various conditions. Results reveal hypoxic zones in high-flow and reflux regions under anoxic conditions, with inlet oxygen concentrations reaching a minimum at 1715 s. Enhanced gas-phase mass transfer stabilizes oxygen levels, reducing iron release and ensuring uniform distribution over time. Impurity nucleation begins in the cold zone beneath the steam generator at 7960 s, highlighting critical areas for management. By coupling reactor-wide oxygen dynamics and impurity behavior, this study underscores the importance of optimized oxygen management to mitigate corrosion, control impurities, and ensure long-term reactor stability, safety, and efficiency.