E3S Web Conf.
Volume 98, 201916th International Symposium on Water-Rock Interaction (WRI-16) and 13th International Symposium on Applied Isotope Geochemistry (1st IAGC International Conference)
|Number of page(s)||5|
|Section||Disposal of Radioactive Waste: Geological, Hydrogeological and Geochemical Aspects|
|Published online||07 June 2019|
Experimental study of multicomponent diffusion in low permeable sediments
Faculty of Geology, Department of Hydrogeology, Lomonosov Moscow State University, GSP-1, Leninskie Gory, Moscow 119899, Russia
* Corresponding author: email@example.com
Diffusion coefficients for Na+ and distribution coefficients for Cs+, Ba2+, Ni2+, CO2+, Sr2+ were measured on low permeable samples (3 cm diameter, average length 7 cm) from the deep disposal site Siberian Chemical Combine (SSC) using the end-diffusion technique. The direction of diffusion was perpendicular to bedding. Special equipment for experiment were designed and constructed. Two types of concentration observation were used. For non-sorbing Na+ in time used EC sensors and length distribution of sorbed elements. The synthetic solution used in the experiments was a model of low-activity contaminant of the SSC, and consist NaNO3 (25 g/l) and nitrate compounds: Cs+, Ba2+, Ni2+, Co2+, Sr2+ (100 mg/l each). The measured values of the effective diffusion coefficients De) for Na+ from 7.60×10-7 to 1.51×10-5 m2/day and volumetric dimensionless distribution coefficients (Kdρ) are: Cs+ from 0.21 to 22.1, Ba2+ from 1.1 to 1.45, Ni2+ from 0.3 to 16.4, Co2+ from 1.98 to 24.7, Sr2+ from 1.9 to 14.3. The values of the diffusion coefficient show a large degree of variability. The diffusion coefficients of non-sorbing Na+ measured in this study are in good agreement with pore-scale diffusion simulation on microtomography data.
© The Authors, published by EDP Sciences, 2019
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