Computational fluid dynamics modeling of high level waste plug formation - 15228
At Hanford, an extensive network of pipelines traversing several miles is used to transfer the high level radioactive nuclear waste from tanks to the treatment facilities. During transfer operations, however, there is a potential risk for the transport lines to plug, causing significant delays, increasing operation costs and creating hazardous conditions for personnel and the environment. In this study we investigate the phenomena of plug formation in the pipelines due to solids depositing during the waste transfer process. A three-dimensional (3-D) Computational Fluid Dynamics (CFD) model has been developed using Comsol Multiphysics 4.3b by Florida International University (FIU) to evaluate the factors that can contribute to pipeline plug formation. Several virtual scenarios are developed simulating the settling mechanics as a function of particle size, solids volume fraction and solids density. The numerical results are validated with the available experimental results and the established critical velocity correlations. The 3-D numerical results were also compared with the previous 2-D numerical studies to understand the trade-off between the two studies in terms of computing speed and numerical accuracy. (authors)