Thermodynamic data are important for the modelling of the chemical processes in the engineering part on nuclear waste repository systems (the "near-field" region), and also to describe the effect of the "far-field", i.e. how the chemical change in ground and surface water systems may affect the transport of toxic elements from the repository to the biosphere.

This publication contains guidelines on how to use the NEA-recommended Thermochemical Database (TDB) values, and on procedures to estimate values for cases where none can be recommended based on published experimental work.