Diffusion of radionuclides in concrete and concrete-bentonite systems

Migration behavior of plutonium affected by ferrous ion in compacted bentonite by using electrochemical technique

“…Figure 8 shows that in short-term tests of up to 6 days, the apparent dispersion coefficient was up to 0. (2) where α is the dispersion length [m] and V a is the apparent migration velocity [m/s]. This equation means that the dispersion coefficient is a sum of the diffusion coefficient and the mechanical dispersion coefficient.…”

“…Plutonium has a very low diffusivity in compacted bentonite under an oxidizing environment. There have been a few studies on plutonium diffusion in compacted bentonite, for example, in a concrete-bentonite system with an experiment duration as long as 5 years [2]. However, there have been few reports on its diffusion behavior under a reducing environment.…”

Waste Volume Reduction Using surface Characterization and Decontamination Laser Ablation

“…Concrete is a complex material comprising many distinct chemical and physical phases on a variety of size scales [6][7][8]. Most studies of radionuclides in cements and concrete are for the most part restricted to phenomenological treatments of diffusion of ions, particularly Cs, in and out of model waste forms and engineered barriers [9][10][11][12][13][14][15][16][17][18][19][20][21]. Few studies exist on the chemical speciation of the contaminants themselves in concrete [22][23][24][25].…”

Near-field/altered-zone models report

“…Fresh concrete and cement phases have been shown to strongly retard and/or immobilize certain actinides and, in some cases, alkali radionuclides (Albinsson et al, 1993;Atkins et al, 1988;Ma et al, 1996). Concrete interaction will alter the chemistry of water contacting the WP and waste form and will affect the interaction between radionuclide-bearing water and other downstream flow-path components such as iron oxides and the host rock.…”