THEREDA - Thermodynamic Reference Database

Part of the process to ensure the safety of radioactive waste disposal is the predictive modelling of the solubility of all relevant toxic components in a complex aqueous solution. To ensure the reliability of thermodynamic equilibrium modelling as well as to facilitate the comparison of such calculations done by different institutions it is necessary to create a mutually accepted thermodynamic reference database. To meet this demand several institutions in Germany joined efforts and created THEREDA [1].

THEREDA is a suite of programs at the base of which resides a relational databank. Special emphasis is put on thermodynamic data along with suitable Pitzer coefficients, which allow for the calculation of solubilities in high-saline solutions. Registered users may either view single thermodynamic data and Pitzer interaction parameters or download ready-to-use parameter files for the geochemical speciation codes PHREEQC, Geochemist’s Workbench, CHEMAPP, or TOUGHREACT. The dataset can also be downloaded in a generic JSON-format to allow the import into other codes. The database can be accessed via the World Wide Web: www.thereda.de

Prior to release, the released part of the database is subjected to many tests. Results are compared to results from earlier releases and among the different codes. This is to ensure that by additions of new and modification of existing data no adverse side effects on calculations are caused. Furthermore, our website offers an in-creasing number of examples for applications, including graphical representation, which can be filtered by com-ponents of the calculated system.

REFERENCES
[1] Moog, H. C., Bok, F., Marquardt, C. M., and Brendler, V.: Disposal of Nuclear Waste in Host Rock formations featuring high-saline solutions - Implementation of a Thermodynamic Reference Database (THEREDA). Appl. Geochem., 55, 72-84, 2015