[en] A programme of work has commenced to assess the radionuclide sorption efficiency of selected inorganic 'getters' incorporated into sulphate resisting Portland cement; as a means of enhancing the retention of radioactive species by the proposed repository backfill. For this initial study, a limited number of radioisotopes have been selected, with particular reference to those likely to be mobile in an alkaline environment, ie. Ra-266, Cs-134 and I-125. The getters chosen for this stage of the programme were Clinoptilolite, Molecular Sieve 5a, Tobermorite and Ferric Floc. (author)