Retention of cesium, plutonium and americium by engineered and natural barriers

Safety assessment of low and intermediate level waste repository requires sorption parameters and understanding of the radionuclides sorption-desorption mechanism. In order to obtain realistic sorption data for safety relevant radionuclides present in cement (concrete) based near surface repository, some preliminary studies have been carried out. Batch sorption experiments were conducted with two clay samples to determine Kd values of Cs, Pu and Am under a wide range of geochemical conditions. Cs, Pu and Am Kd values were determined for rainwater, groundwater and cement-water of different chemical compositions. Cs, Pu, Am Kd values ranged from 450 to 9700, from 15000 to 21000 and from 15000 to 80000 ml/g, respectively. Iron speciation was determined using Moessbauer spectrometry. (author)