A geological repository of spent nuclear fuel (SNF) and high-level waste (HLW) has not been realized in any country so far, but a lot of experience is collected in the assessment of radionuclide migration from geological repositories. Various processes influencing the safety of a disposal system are also investigated.

Solubility of radionuclides released into aqueous environment is one of the key factors influencing the fate of radionuclide transport out of the repository and consequently, the safety of the environment. The ability to model radionuclide dissolution under repository conditions is an important issue when assessing the safety of a disposal system.

In this paper, the solubility assessment route for geological disposal is reviewed within the context of the methodology developed by the International Atomic Energy Agency (IAEA) on Improvement of Safety Assessment Methodologies for Near Surface Disposal Facilities (ISAM). Necessary information for the modelling of radionuclide solubility limits is identified as well. This information will serve as a basis for the further research estimating radionuclide solubility under the conditions similar to those in potential sites for SNF disposal in Lithuania.

Keywords: spent nuclear fuel, geological disposal, solubility assessment, geochemical modelling