This report presents the most up-to-date understanding of technetium chemistry and transport behaviour in the Boom Clay formation (status 2010). Technetium is a redox-active fission product, with tetravalent Tc being the thermodynamically stable species under far field conditions in the Boom Clay. Tetravalent Tc readily associates with dissolved organic matter (DOM) at circumneutral pH, and the resulting Tc-DOM colloid dominates Tc transport. Tc-DOM colloids migrate through Boom Clay almost unretarded, but slowly dissociate. The dissociated Tc has a very high affinity for sorption sinks on the solid Boom Clay phase. The bulk migration of Tc therefore shows considerable retardation. The phenomenological model for Tc-DOM migration is assumed to be similar for all radionuclides which show affinity towards Boom Clay organic matter.
|Number of pages
|Published - Oct 2010
|Studiecentrum voor Kernenergie