A Study on the Effect of Clay Particle Orientation on Diffusion in Compacted Bentonite [electronic resource].
- Published:
- Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2002.
- Physical Description:
- 16 pages : digital, PDF file
- Additional Creators:
- United States. Department of Energy. Office of Scientific and Technical Information
Access Online
- Restrictions on Access:
- Free-to-read Unrestricted online access
- Summary:
- In this study, the effect of the orientation of clay particles on diffusion in compacted bentonite, which is regarded to be quite important as a candidate buffer material in safety assessment for a geological disposal of high-level radioactive waste, was experimentally discussed by investigating effective diffusion coefficients (De) for tritiated water (HTO), which is non-sorptive onto bentonite. The diffusion experiments were carried out for 2 kinds of smectite contents of Na-bentonites, Kunigel-V1{reg_sign} (content of Na-smectite, 46-49wt%) and Kunipia-F{reg_sign} (content of Na-smectite, > 99wt%) at dry densities of 1.0 and 1.5 Mg/m3 by a through-diffusion method. The through-diffusion experiments were carried out for the same direction as compacted direction of bentonite and perpendicular direction to compacted direction. Scanning electron microscopic (SEM) observations for the cross section of bentonite in the axial and perpendicular directions to compacted direction of bentonite were also carried out at dry densities of 1.0, 1.6, and 2.0 Mg/m3. Although De values for Kunigel-V1{reg_sign} were approximately the same for both diffusion directions to compacted direction over the densities, and no anisotropy in De was found, De values in the perpendicular direction to compacted direction for Kunipia-F{reg_sign} were clearly higher than those in the same direction as compacted direction. In the SEM observations, no significant orientation of clay particles was found for Kunigel-V1{reg_sign} over the densities, while the orientation of clay particles was clearly found for Kunipia-F{reg_sign}, and the degree of the orientation of clay particles became significant with an increase in dry density of bentonite. This tendency is in good agreement with that for De values obtained, indicating that smectite content in bentonite affects the orientation property of clay particles, and that the orientated clay particles affect diffusion pathway.
- Report Numbers:
- E 1.99:828424
- Subject(s):
- Other Subject(s):
- Note:
- Published through SciTech Connect.
02/26/2002.
Waste Management 2002 Symposium, Tucson, AZ (US), 02/24/2002--02/28/2002.
Sato, H.
Japan Nuclear Cycle Development Institute 4-33 Muramatsu, Tokai-mura, Naka-gun, Ibaraki-ken 319-1194 (JP)
View MARC record | catkey: 14380114