Sorption of Cs-137 radionuclide into clay stone of Subang formation as potential area for rad waste disposal

Sorption of Cs-137 radionuclide by clay rock from potentially area in Jawa Island such as Subang area for radwaste disposal had been done. When radionuclides interacted with rock around disposal facility usually radionuclides sorption into host rock occurred, one of used method is placed waste packages on clay typed host rock and this method could be restrict distribution of radionuclides into environment. Other reason, clay rock also use as barriers in the disposal of radioactive waste and the experiments of sorption of Cs-137 by clay rock from potentially area such as Subang area important to be done. Batch method was used in the experiments. Taking out data was sorption-desorption Cs-137 data as functions of time, CsCl concentrations, ionic strength, and effect of coexistence ions. Objective of experiment was to known reliability of Indonesian local host rock from Subang area if use as radwaste disposal facility in the future. Distribution coefficient was found from the experiment was 5200 and 90 ml/g with contact time 190 and 150 hours for 10^-8 and 10^-3 M CsCl, respectively. Contact time for desorption kinetic was 150 hours with new Kd values 2900 and 56 ml/g for 10^-8 and 10^-3 M CsCl, respectively. Increasing in CsCl concentrations in solution will decrease on Kd value of Cs by clay, and increased in concentration of background salt affect on Kd of Cs by clay due to competition of Na and Cs ions in solution. Increased in valence of coexistence ions will decrease on Kd values, and its affectivity in solution will follow as Ca²⁺ > Mg²⁺ > K⁺ > Na⁺. (author)