Formation and transport of lead oxide in a non-isothermal lead-bismuth eutectic loop

Highlights: • Formation of suspended lead oxide particles in lead-bismuth eutectic is observed. • A lead oxide formation model is successfully coupled with LBE thermal-hydraulics. • Simulation results are validated based on oxygen concentration measurements. • Majority of lead oxide particles are expected to be of submicron size. - Abstract: Lead oxide (PbO) formation can occur in Lead-Bismuth Eutectic (LBE)-cooled nuclear systems in case of oxygen ingress or temperature decrease of the coolant beyond the normal operation ranges. In the present work the formation of lead oxide in an actively cooled LBE flow is studied. Computational fluid dynamics (CFD) is used to predict the nucleation, growth and dissolution of PbO particles. Solid oxide particles are modeled as a pseudo-continuous phase, using the Kinetic Theory of Granular Flow (KTGF) to account for particle-flow interaction. The particle size distribution (PSD) is accounted for using Population Balance Equations/Models (PBE/PBM). The results obtained from the model are qualitatively in good agreement with experimental results obtained in the MEXICO loop at SCK·CEN. The calculated PSD reveals that the majority of the oxide particles are expected to be in the sub-micron range. Experimental results indicate that in the studied conditions PbO nucleates in the LBE bulk leading to suspended particles in the LBE flow.