Review of the sorption data of the main radionuclides in low and intermediate level nuclear wastes for Finnish bedrock

This report summarizes the studies on sorption of radionuclides in Finnish bedrock performed at the Department of Radiochemistry University of Helsinki. Sorption data for backfill and construction material are also included. Samples represent common rocks, minerals, construction and backfill materials at the sites in the prposed repositories for low and intermediate level nuclear wastes at Haestholmen (IVO) and Olkiluoto (TVO). Sample types used for sorption experiments were crushed rock and concrete, mineral and rock thin sections, rock pieces, 'drill core cups' and natural fracture surfaces. The method used for determination of Ksub(d)-values was the batch method. The determination of Ksub(a)-values was performed by the autoradiographic method. The radionuclides discussed in this report are 134Cs, 85Sr, 89Sr, 58Co, 63Ni, 125I, 99Tc and 14C. Recommended sorption data (Ksub(d) and Ksub(a)-values) for use in safety analyses in migration modelling are presented. For conservative evaluation the values selected are minimum values from two or three parallel determinations. When only one Ksub(a)-value of radionuclide was available for a rock species that value was considered as recommended value. (author)