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NEA Thermochemical Database (TDB)


In 1986, the Nuclear Energy Agency (ΝΕΑ) of the Organisation for Economic Co-operation and Development (OECD) undertook the development of the Thermochemical Database (TDB), a critically evaluated chemical thermodynamic database for a number of elements and ligands of interest to nuclear technology, in particular to the performance assessment of geological repositories for spent nuclear fuel and radioactive waste. The critical assessment procedure applies rigorous evaluation techniques such as a uniform method to treat ionic strength dependencies and uncertainties. Equilibrium constants are categorised as either (i) recommended values, which are summarised in the “Tables of selected values” in the books and included in the NEA electronic database (see below), or (ii) data labelled as “for scoping calculations” or as “for qualitative modelling”, which are important for geochemical modelling but are known with lower certainty than the recommended values.


Fifteen volumes of the Chemical Thermodynamics Series have been produced so far, totalling more than 11’500 pages of documentation. The recommended data refer to the standard state and to 25 °C; extensive discussions of the data analyses and review processes are made available in the interests of transparency. Regarding the data labelled “for scoping calculations”, it is up to the user to read the documentation and to find the useful data.

NEA published volumes

System Reference
Uranium Grenthe et al. (1992, reprinted in 2004)
Americium Silva et al. (1995, reprinted in 2004)
Technetium Rard et al. (1999, 2nd update in 2020)
Neptunium and plutonium Lemire et al. (2001)
Update of uranium, neptunium, plutonium, americium and technetium Guillaumont et al. (2003, 2nd update in 2020)
Nickel Gamsjäger et al. (2005)
Selenium Olin et al. (2005)
Zirconium Brown et al. (2005)
Compounds and complexes of U, Np, Pu, Am, Tc, Se, Ni and Zr with selected organic ligands Hummel et al. (2005)
Solid solutions – state-of-the-art report Bruno et al. (2007)
Thorium Rand et al. (2008)
Tin Gamsjäger et al. (2012)
Iron – Part 1 Lemire et al. (2013)
Iron – Part 2 Lemire et al. (2019)
Second update of uranium, neptunium, plutonium, americium and technetium Grenthe et al. (2020)


All volumes in the series can be downloaded from the NEA website. Note that Bruno et al. (2007) is a “state-of-the-art” report on solid solutions and does not contain any thermodynamic data.

An interactive TDB electronic database, e-TDB, is available. Registration with the NEA is required in order to obtain access. The content of the e-TDB includes (a) all recommended thermodynamic data of the 14 Chemical Thermodynamic Series volumes, (b) a PHREEQC formatted database file, ready to download and use, and (c) searchable information on all the bibliographic references that have been used in the TDB published material.