An attempt to select thermodynamic data and to evaluate the solubility of radioelements with uncertainty under HLW disposal conditions

An attempt was made to select thermodynamic data with uncertainties and to evaluate the solubility of radioelements with uncertainties considering the uncertainties of the thermodynamic data and variation in groundwater chemistry. The thermodynamic data were selected by reviewing the JAEA-TDB released in 2012 from the viewpoint of consistency of the data selection process, the conservativeness of the solubility evaluation and testing up-to-date data. A Monte Carlo-based probabilistic solubility calculation code, PA-SOL, was used for the uncertainty analysis of the solubility. The uncertainty analysis for the solubility of 13 elements showed large uncertainties for Nb, Tc and U. The variations in pH, pe and total carbonate concentration assumed in this study induce significant uncertainties to the evaluated solubility. The reactions whose log K-0 with uncertainties induce significant uncertainties to the evaluated solubilities were identified.