Study on criteria and prediction method of liquid fall type gas entrainment in pool-type sodium-cooled fast reactors.

• An experimental phenomenon was used to verify numerical model and method. • The modeling criteria of simulating sodium entrainment by other liquids were determined by simulation results. • The relation of critical re-submergence velocity can be accurately concluded and validated. • An improved wide-applicable prediction method was proposed for entrainment situation judgment. Liquid fall type entrainment, a kind of gas entrainment phenomenon which may undesirably occur in sodium-cooled fast reactors (SFRs) due to complex immersed structures and high-velocity flowing coolants of SFRs, will involve bubbles into coolants and lead a series of safety risks. Aiming at providing a guideline for avoiding this phenomenon, the computational fluid dynamics (CFD) method was adopted to investigate the influences of fluid properties on entrainment initiation. Before the simulation case study, a small-scale experiment was conducted for verification which demonstrated the numerical model and VOF method are suitable for this study. The modeling criteria of simulating sodium entrainment by other liquids were determined by simulation results. It was also found that the relation between critical inlet velocity and σ / ρ , and the relation between critical re-submergence velocity and critical inlet velocity can be accurately estimated by the case validation. Based on which, an improved wide-applicable prediction method was proposed for entrainment situation judgment. [ABSTRACT FROM AUTHOR]