Physical Property Models of Concentrated Cesium Eluate Solutions

Major analytes expected to be present in the WTP cesium ion-exchange eluate solutions were identified from the available analytical data collected during radioactive bench-scale runs, and a test matrix of cesium eluate solutions was designed within the bounding concentration ranges of those major analytes. A computer model describing the semi-batch evaporation of cesium eluate solutions was built using the Environmental Simulation Program (ESP), licensed by OLI Systems, Inc., and was run to calculate the physical properties of each test matrix solution concentrated to the target endpoints of 80 percent and 100 percent bulk saturation. The calculated physical properties were then analyzed statistically and fitted into predetermined mathematical expressions for the bulk solubility, density, viscosity and heat capacity as a function of temperature and feed concentration of each species considered in the matrix. In addition, the volume reduction factor, which is defined as the ratio of total cumulative feed volume to that of the initial acid charge, was calculated and modeled for the 80 percent saturation case. The R2 of the resulting physical property models ranged from 0.89 to 0.99. Validation of these physical property models against the true experimental data was not part of the current work scope; instead, the results of model validation will be discussed later in another report, after all the necessary data for model validation have been collected and analyzed