Evaluation of Radiocesium Sorption in Some Materials as Safety Barrier System of Radioactive Waste Disposal Demonstration Facility

Sorption characteristic study of the prospective barrier materials will be used as safety barrier system on the disposal facilities such as bentonite, kaolinite, and quartz sandy has been done. Such barrier materials were contacted against 137Cs with affected parameters were the functions of contact time, concentration of CsCl, ionic strength of solution, and the sorption isotherm, and all the experiments were done in batch method. Objective of the research is to obtain a specific sorption character data of radiocesium into some prospective barrier materials for radioactive waste disposal demonstration facility at Serpong. The initial concentration of CsCl being used was 10-8 M, and 0.1, 0.5, 1.0 M NaCl and also 10-8-10-4 M CsCl for experiments of the effects of shaking time, ionic strength and concentration of CsCl in the solution, respectively. Sorption quantification of 137Cs was predicted through their distribution coefficient (Kd). Equilibrium state were reached after 7, 5 days and 24 hours shaking time with Kd values 17000; 1100 and 130 mL/g for bentonite, kaolinite and quartz sandy samples, respectively. Increasing of NaCl and CsCl concentrations in solution caused Kd values decreased due to the competition between Na and Cs ions when interacting with the sample, and also due to the limited sorption capacity of the sample to 137Cs.