Sorption of strontium, cesium, nickel, iodine and carbon in concrete

Concrete have been suggested to use as contruction material for the respositories of low and medium level radioactive wastes. In this study the sorption of the most important radionuclides in low and medium level wastes, strontium, cesium, iodine, nickel and carbon, was studied. The determinations were made at ambient atmospheric conditions with natural groundwaters from nuclear power plant sites (Haestholmen and Olkiluoto). The samples were crushed concrete and concrete coupons. The order of sorption obtained for crushed samples and coupons was Ksub(d)sup(Ni) > Ksub(d)sup(C) > Ksub(d)sup(Cs) > Ksub(d)sup(I) > Ksub(d)sup(Sr). Autoradio graphy was used for detection of differences in sorption on the cement fraction and on the sand ballast. The sorption of cesium and carbon occured on the sand fraction. Iodine was mainly sorbed by the cement. For strontium and nickel there was no clear difference in sorption between cement and sand ballast. The mean values of the penetration depths of studied radionuclides into concrete coupons were calculated assuming the same Ksub(d)-value per mass for crushed concrete and coupons. The order of the penetration depth was Sr > I > C > Cs