CFD Evaluation of Mixing Processes for High-Level Nuclear Waste Tanks

Abstract

Computational Fluid Dynamics (CFD) has been applied to investigate two aspects of a mixing process for high level nuclear waste tanks. Through CFD the applicability of Poreh's correlations that are currently used to describe the radial wall jets in the Pulse Jet Mixing (PJM) process were assessed. In addition, simulations were conducted in order to investigate mean hydrodynamic characteristics of sparged non-Newtonian fluids for the use in the PJM process.Three single phase turbulent simulations using the commercial package STAR-CCM+ were successively conducted. A model validated with experimental data was developed and successively altered to see the effects of low characteristic ratio and a curved impingement surface. Results suggested that Poreh's correlations are applicable under PJM conditions and geometry.Lastly, multi-phase Eulerian-Eulerian Simulations were conducted using the commercial software package ANSYS Fluent. Altering the characteristic ratio (h/D) of a sparged non-Newtonian fluid system resulted in a trend of flattening air volume fraction and air axial velocity profiles with decreasing characteristic ratio.