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Mukai, Masayuki; Tanaka, Tadao; Yukawa, Kazuhiko; Suryantoro*
Genshiryoku Bakkuendo Kenkyu, 12(1-2), p.41 - 51, 2006/03
To evaluate radionuclides migration through geologic media coexistent with colloids in groundwater, a model has been coded. To evaluate an applicability of four models to colloid transport through porous media, breakthrough curves (BTCs) from column experiments using sand and reddish soil have been analyzed. Instantaneous equilibrium model could not explain both timings of breakthrough and reach to C/C
=1 concurrenyly, however 1st order kinetic reaction model successfully simulate them well. BTCs from the reddish soil column have a particular feature that shows step-wise rising pattern in response to alternately inflow of colloid. Both the instantaneous equilibrium, the 1st order kinetic reaction and filtration models could not simulate this feature, however a 1st order kinetic reaction with filtration capacity model reasonably simulates the feature. The model for colloid transport, given an important role as a part of colloidal migration model of radionuclide, has been validated on the basis of the laboratory experiments.
Mukai, Masayuki; Ueda, Masato; Inada, Daisuke; Yukawa, Kazuhiko; Maeda, Toshikatsu; Iida, Yoshihisa
Proceedings of International Symposium NUCEF 2005, p.219 - 224, 2005/08
For better quantitative understanding of radionuclide migration for safety assessment of geologic disposal, JAERI has been conducting experimental and modeling studies on influences of humic substances, highly alkaline conditions and colloids on sorptive and diffusional behavior of TRU in geologic materials. In the absence of fulvic acid, one of humic substances, diffusion of Am through a tuff sample was not detected. By adding fulvic acid, Am was detected in the downstream cell, which indicates the diffusion through the sample. Highly alkaline conditions arisen from cementitious materials may spread by altering chemical and physical properties of geologic materials. Through-diffusion experiments of alkaline species in granite showed that the effective diffusion coefficient of Ca and OH
in a cement-equilibrated aqueous solution were found to be higher by almost two orders of magnitude than Na
and OH
in a NaOH solution. Radionuclide migration can be enhanced by colloids, and thus a calculation code describing the effect of colloids on radionuclide migration has been required.