Welcome to THEREDA

The Thermodynamic Reference Database (THEREDA) is designed for geo-chemical models in the context of a radioactive waste repository. The primary focus is on the correct calculation of the solubilities of radionuclides, fission products and matrix elements (construction materials and mineral phases of the surrounding host rock).

THEREDA especially addresses high-salinity aqueous solutions (brines) and therefore supports the Pitzer ion-interaction approach. Great effort has been made to ensure the internal consistency of the data.

For the oceanic salt system, THEREDA is applicable in the temperature range from 0 to 110 °C, for some subsystems even beyond. As such, THEREDA is    the only database in the world that polythermally covers the entire system of oceanic salts. The current radionuclide selection includes actinides (Th, U, Np, Pu, Am, Cm) and fission products (Se, Sr, Tc, Cs). There is also data for some heavy metals (Pb, Zn) available. The majority of the data for these radionuclides is valid for 25 °C.

THEREDA can export ready-to-use parameter files in the formats of commonly used geochemical codes: Geochemist's Workbench and PHREEQC/PhreePlot.

THEREDA's data set is regularly benchmarked by recalculating experimental measured values, with all results documented in the "Application examples" section.

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Application examples

An extensive survey of all tested systems can be accessed using the menu item Application Examples

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Data release 2023

The THEREDA management board announces a new data release. Major changes or additions compared to the former release are:

  • Systems NaOH - Mg(OH)2 - Ca(OH)2 - CO2(g) – H2O(l) (polythermal)
  • Systems Mg2+ – Cl – OH – H2O(l) (polythermal)
  • Systems Na+ – Mg2+ – Cl – OH – H2O(l) (polythermal)
  • Systems Zn2+ – Na+ – K+ – Mg2+ – Ca2+ – Cl – SO42− – OH – H2O(l) (25°C)
  • U(+IV)-Hydrolysis and -solubility: Systems U(+IV) – Na+ – Mg2+ – Ca2+ – H+ – OH – Cl – H2O(l) (25°C)
  • Systems Al(OH)4 – Si(OH)4(aq) – Na+ – K+ – Ca2+ – Mg2+ – Cl – SO42− – CO32− – H2O(l) (polythermal)
  • Double salt CsCl-NaCl and solid solution (25 °C)
  • Update for systems O2(g) – Na+ – K+ – Mg2+ – Ca2+ – Cl – SO42− – CO32− – PO43− – OH – H2O(l)(polythermal except for carbonates and phosphates)

The complete release has been extensively tested in 296 test cases including more than 1400 numerical results for the following codes:

  • Geochemist's Workbench
  • PHREEQC

Support for CHEMAPP and TOUGHREACT has been abandoned. As in the former release we also offer a JSON-formatted version.

Due to the increasing complexity of the database it is possible to run calculations for systems for which THEREDA isn't qualified. Therefore, users are advised, to have a look on our continously growing list of application examples.

On 2024-04-08 the release was revised. Fixed errors:

  • Water stability line at p(H2) = 1 atm was wrong (GWB only)
  • Miscibility gap in solid solution SO4-CO3-AFt_ss was wrong

Key References

If you want to read more on THEREDA or cite the THEREDA database in your publications, you can use these references:

Project Funding

THEREDA is funded by BGE – the federal company for radio-active waste disposal, with the contract number 45181017.