Technical Report NTB 89-02
Geochemical database for the sediment studyIntermediate report 1988
This report documents the geochemical database which was used for the safety assessment of two sedimentary formations: the Lower Freshwater Molasse (Untere Süsswassermolasse, USM) and the Opalinus Clay (Opalinuston, OPA). The database was used for the "Sediment-Zwischenbericht" study of HLW disposal in Swiss sediments (Nagra 1989). The in-situ geochemistry of the groundwaters has been derived from available water sample analyses, assumptions based on mineralogical and literature data, as well as on computer calculations.
The available data (geology, geochemistry/petrography, organics, gas, hydrochemistry) allow the definition of geochemical Reference Conditions (RC) for the potential repository site. This information is then used to calculate the associated Reference Waters (RW).
A sorption database for modelling radionuclide transport in these formations is presented. In addition, possible geochemical perturbations due to the presence of colloids, microorganisms or organic carbon are discussed.