Simulation Study of Sludge Precipitation in Spent Fuel Reprocessing

A simulation technology with electrolyte thermodynamic model has been developed to evaluate the precipitation behavior in reprocessing solution. In this study, we have chosen the model of OLI system Inc. which combines an excess Gibbs energy model for mixed-solvent electrolyte systems with a comprehensive treatment of chemical equilibrium. The simulation results of precipitation were compared with the experiment data from non-radioactive simulated HLLW and Pu-Zr-Mo solution, and they showed good agreement each other. Most of the precipitation species was zirconium molybdate hydrate (ZMH) from the both data. This study has shown the thermodynamic simulation model is one of the useful tools to estimate the behavior of precipitation species from the reprocessing solution.