Study of uranium and thorium behaviour in argillaceous sediments. Natural analogue study at the Ruprechtov site, Czech Republic

The pilot phase of the Ruprechtov Natural Analogue Study Project (1996-1998) was aimed at describing and characterizing a sedimentary system where a detailed study of the behaviour U and Th in bentonite sediments and of the barrier material itself were planned. The pilot phase of the project proved that the Ruprechtov site (Western Bohemia, Czech Republic) is well suited to the investigation of materials and processes analogous to those which bentonite/clay material can undergo during a long term performance of the barrier system in a deep radioactive waste repository. Accumulation of U in Tertiary clay sediments (argillized tuffs) was observed at the site. The basic geological, geochemical and hydrogeological parameters of the argillaceous sediment environment, i.e. characteristics of the sediment, ground water and pore water, were determined and evaluated