Diffusion of Chloride and Uranium in Compacted Sodium Bentonite

Abstract

Sorption and diffusion of chloride (Cl-36) and uranium in conpacted sodium bentonite MX-80 were measured. No sorption was observed in the Sorption tests, however, in the diffusion tests slight sorption of uranium was noticed. The diffusivities of Cl-36 were found to be strongly dependent on the compaction of bentonite and on the salt concentration of the solution. Ion-exclusion can propably explain these phenomena.The diffusivities of uranium were also strongly dependent on the compaction of bentonite. Uranium shews features of both ion-exclusion and sorption. Farther studies are, however, needed to explain the diffusion mechanisms of uranium.

A modified version of Archie’s law to estimate effective diffusion coefficients of radionuclides in argillaceous rocks and its application in safety analysis studies

“…Both throughdiffusion (HTO) and X-ray radiography techniques (I À ) were used to measure effective diffusion coefficients and diffusion accessible porosities. Also two sets of diffusion data for 36 Cl À measured on compacted bentonite were added (Muurinen et al, 1989;Van Loon et al, 2007). Fig.…”

Self-Diffusion of Water and Ions in Clay Barriers

“…where q nano 1 is a parameter that accounts for the slower diffusion dynamics of water and solutes in the vicinity of clay surfaces than in bulk liquid water (Kemper et al, 1964;Li and Gregory, 1974;Bourg et al, 2006;González Sánchez et al, 2009;Holmboe and Bourg, 2014), f e f is an effective "anion-accessible" porosity that accounts for anion exclusion in the EDL (van Schaik and Kemper, 1966;Muurinen et al, 1989;Mazurek et al, 2011;Shackelford and Moore, 2013)…”

Ion equilibrium between montmorillonite interlayer space and an external solution—Consequences for diffusional transport

“…(20) has also been tested against data measured by Muurinen et al (1989) on sodium dominated Wyoming type bentonite (MX-80, CEC % 0.8 eq/kg dry clay), in the same manner as above. The result is presented in Fig.…”

“…Comparison of calculated values of N Cl À (Eq. (20)) with values derived from diffusion measurements by Muurinen et al (1989). X = 800 mol/m 3 , q s = 2800 kg/m 3 and C 1 = 1.…”