期刊名称：International Journal of Energy and Environment
印刷版ISSN：2076-2895
电子版ISSN：2076-2909
出版年度：2011
卷号：2
期号：3
页码：491-504
出版社：International Energy and Environment Foundation (IEEF)
摘要：A numerical model is developed for studying the transport of colloid facilitated radionuclide transport in a coupled fracture-matrix system. The radionuclides and the colloids are assumed to decay, sorb on the fracture surface, as well as diffuse into the rock matrix. The sorption of the radionuclides onto the mobile and immobile colloids within the fracture is assumed to be linear. The governing equations describing the radionuclide and colloidal transport along the fracture axis and diffusive mass transport within the rock matrix, which is normal to the fracture axis are coupled together, while maintaining the continuity of fluxes at the fracture-matrix interface. Constant concentration is assumed at the inlet of the fracture for both colloids as well as radionuclides and varying grid is adopted at the fracture and rock-matrix interface to capture the flux transfer. Spatial moments are performed on the concentration profiles of the radionuclides in order to investigate the impact on the mobility and dispersion behavior of the radionuclides. Results suggest that a combination of fluid velocity and colloidal velocity, which influences the residence time of radionuclides within the fracture (against sorption onto the fracture walls, diffusion into the rock-matrix and sorption onto the colloids) ultimately decides the mobility of radionuclides. The presence of colloids retards the mobility of radionuclides in the aqueous phase. The presence of colloids have reduced the mixing of radionuclides within the fractures significantly as against the mixing experienced in a coupled fracture-matrix system in the absence of colloidal transport.
