To retrieve radioactive waste from a tank for treatment and disposal, jet mixer are used to stir radioactive sludge, salt cake, and supernatant liquid. This approach produces slurry that can be easily removed from a tank. During the waste retrieval process, complex interactions occur among waste mixing, chemical reactions, and associated Rheological phenomena. To determine safe and cost-effective operational parameters for waste retrieval, decisions must rely on new scientific knowledge to account for physical mixing of multiphase flows, chemical reactions, and waste Rheological characteristics. Thus, it is important to investigate the interactions between the Rheological features and mixing processes. The objective of this study is to investigate the effect of jet pulsing on the mixing of non-Newtonian fluids in storage tank using laser diagnostic techniques. Particle Image Velocimetry (PIV) technique with high spatial and temporal resolution is used in this study to measure the flow pattern and mixing properties of non-Newtonian fluid in storage tank. The study focuses on the effects of fluid Rheological characteristics (viscosity, shear stress, shear rate), jet characteristics (exit velocity, Reynolds number), and jet pulsing conditions (frequency) on the mixing of non-Newtonian fluid flows. The results presented in this paper will show (1) the effect of jet pulsing frequency (f = 1 - 120 Hz) on the mixing process of non-Newtonian fluids and (2) the pulsing conditions leading to the optimum mixing (efficient distribution of the feed into the bulk tank volume and fluid velocity magnitude used to maintain solids in suspension and mobilize sludge from the tank floor). The results obtained in the course of this study are used as an assessment tool to support decisions made during waste retrieval operations.
