This report presents the most up-to-date understanding of caesium (Cs) chemistry and transport behaviour in the Boom Clay formation (status 2010). The behaviour of caesium in clay host rocks and engineered barriers has been the subject of many studies worldwide. Also in Belgium the studies on the interaction of Cs with Boom Clay started many years ago and are still ongoing. This report discusses the experimental data obtained within these studies and the concepts used to interpret these data. The data and concepts are evaluated against published and generally acknowledged phenomenological models from similar geochemical studies. From this discussion, a phenomenological model is developed that is applicable to describe caesium transport under present-day conditions in Boom Clay at the Mol site. Moreover, the parameter values needed in the model are extracted and evaluated. These parameters are either a so-called “best estimate” (the most representative value for a given parameter best suited to describe caesium migration), an “expert range” (the range of values within which experts expect the parameter value to lie), or a “source range” (the range of values outside of which the parameter value is very unlikely to lie, considering current knowledge).
|Number of pages
|Published - Feb 2011
|Studiecentrum voor Kernenergie