Retention of radionuclides by sorption and ion-exchange is an important mechanism ensuring the long-term safety of a clay-based host rock for geological disposal radioactive waste.
A lot of attention is therefore given to achieve understanding of these processes and to acquire quantitative data for safety assessment calculations.
In this respect, the key parameter in the transport calculations is the apparent diffusion coefficient Da. These values are either determined directly from diffusion experiments or they are calculated from separately derived parameters: effective/pore diffusion coefficient (De/p) and distribution coefficients (Kd or Rd) measured from batch experiments.
However, are sorption values measured in batch tests on dispersed material compatible with those deduced from diffusion experiments on intact rock? This issue is still a matter of debate.
The sorption and diffusion behaviour of Cs, Sr and Am/Eu were investigated as representatives for mono-, di- and trivalent sorbing cationic radionuclides in Boom Clay.
Based on the available data it was possible to give a positive answer with respect to the question: "are sorption values measured in batch tests on dispersed material compatible with those deduced from diffusion experiments on intact rock material?" – at least for radionuclides that are sorbed mainly by cation-exchange.
|Number of pages
|Published - Dec 2009
|Studiecentrum voor Kernenergie