Technical Report NTB 09-08

Physico-Chemical Characterisation Data and Sorption Measurements of Cs, Ni, Eu, Th, U, Cl, I and Se on MX-80 Bentonite

This report describes the work carried out in LES on MX-80 bentonite in support of Swiss radioactive waste performance assessment studies. With particular regard to Stage 2 of the Sectoral Plan for deep geological disposal, it was considered to be important to bring together in one document the information and results that have accrued over the years from both “in house” studies and associated relevant literature data. The report gives a brief overview of the physico-chemical characteristics and porewater chemistry determined for MX-80 bentonite followed by the results of an extensive experimental sorption programme on the uptake of Cs(I), Ni(II), Eu(III), Th(IV), U(VI), Cl(-I), I(-I) and Se(IV) on the same material. Sorption values are also given for K(I), Ca(II) and Sr(II) which were deduced from porewater chemistry modelling studies.