Simulating the dynamics of spouted bed nuclear fuel coaters

We describe the status of simulating the dynamics of spouted beds used for chemical vapor deposition on nuclear fuel particles. Our principal modeling tool is the MFIX (Multiphase Flow with Interphase exchanges) code (http://www.mfix.org) originally developed by the National Energy Technology Laboratory (NETL) for fossil energy process applications. In addition to standard MFIX features that allow coupling of hydrodynamics, heat and mass transfer, and chemical kinetics, we employ special postprocessing tools to track particle mixing and circulation as a function of operating conditions and changes in bed design. We describe in detail one particular aspect of the dynamics, nearly periodic pulsations of the inlet gas flow. These pulsations appear to be a critical component of the solids circulation and allow direct comparisons of model predictions with experiments. Future planned research directions for nuclear fuel coating process improvement are also summarized.