The sparingly soluble ThO2 dissolution behaviour was studied under conditions that are expected to prevail in bedrock after the closure of the spent nuclear fuel disposal facility. The objective was to investigate the characteristics of initial dissolution of crystalline (ThO2)-Th-232 by adding Th-229 tracer to the aqueous phase in the beginning of the 534 days experiment.The evolution of Th-232 concentration and Th-229/Th-232 ratio were followed by sector field ICP-MS (inductively coupled plasma mass spectrometer). Selected samples were measured also by alpha spectrometry to compare the results from the used analysis techniques and they gave comparable results. In the early stage of dissolution there was no significant control by chemical equilibrium and the dissolution process seemed to be controlled by the stability of surfaces.
Fields of Science
- 116 Chemical sciences