Argon entrainment into liquid sodium in fast breeder reactor

Gas entrainment in pool type sodium cooled fast breeder reactors has been a subject of great interest for a quite long time now. The issue of entrainment of argon cover gas in LMFBR's is being addressed by fundamental studies. Present work focuses on characterization of onset of shear type entrainment and liquid fall type entrainment based on mean velocity and turbulent kinetic energy at liquid surface. Study also includes characterization of onset of vortex type entrainment based on mean velocities (time averaged) in the outlet pipe. Experiments were carried out to characterize shear type entrainment in stirred tank with different impeller geometries with air–water and xylene–water systems. Onset of liquid fall type entrainment was studied with cylindrical tank with a nozzle whose input angle varied. Mean and r.m.s. velocity profiles near the liquid surface were measured with the help of ultrasonic velocity profiler (UVP). The results are compared with other literature. It is observed that the onset of entrainment can be characterized by the turbulent kinetic energy near the free liquid surface. Re-submergence angle was measured and r.m.s. velocities found to be in the same range as in case of shear type of entrainment. Cylindrical tank with tangential inlet and bottom outlet was used to study onset of vortex formation. Effect of different parameters like outlet diameter, tank diameter and liquid height in the tank on critical velocity was studied and correlation has been proposed.

► In the present work, different types of entrainment mechanisms have been studied.
► Onset of entrainment could be characterized with turbulent intensities.
► For vortex type entrainment, a correlation has been proposed.