Effect of exchangeable cations on apparent diffusion of Ca ions in Na- and Ca-montmorillonite mixtures

Kozaki, Tamotsu*; Sawaguchi, Takuma; Fujishima, Atsushi; Sato, Seichi*

Physics and Chemistry of the Earth, 35(6-8), p.254 - 258, 2010/00

https://doi.org/10.1016/j.pce.2010.04.006

Compacted Na-bentonite, of which the major mineral is montmorillonite, is a candidate buffer material for the geological disposal of high-level radioactive waste. A potential alteration of the bentonite in a repository is the partial replacement of the exchangeable cations of Na with Ca. The Ca cations could be released from cementitious materials and diffuse into the buffer material in the repository. In this study, to evaluate the alteration that could reduce the performance of the bentonite buffer, the apparent diffusion coefficients of HTO and Ca ions were determined from non-steady, one-dimensional diffusion experiments using Na- and Ca-montmorillonite mixtures with different ionic equivalent fractions of Ca ions. The apparent diffusion coefficient of HTO at a dry density of 1.0 Mg m slightly increased with an increase in the ionic equivalent fraction of Ca ions. However, the apparent diffusion coefficient of Ca and the activation energy for diffusion at the same dry density were independent of the ionic equivalent fraction of Ca ions. These findings suggest that unlike HTO, which can be postulated to diffuse mainly in pore water, Ca ion diffusion could occur predominantly in interlayer spaces.

Development and management of the knowledge base for the geological disposal technology; Annual report 2006

Umeda, Koji; Oi, Takao; Osawa, Hideaki; Oyama, Takuya; Oda, Chie; Kamei, Gento; Kuji, Masayoshi*; Kurosawa, Hideki; Kobayashi, Yasushi; Sasaki, Yasuo; et al.

JAEA-Review 2007-050, 82 Pages, 2007/12

JAEA-Review-2007-050.pdf:28.56MB

This report shows the annual report which shows the summarized results and topic outline of each project on geological disposal technology in the fiscal year of 2006.

None

; Fujishima, Atsushi

JNC TN1400 2002-014, 15 Pages, 2002/09

JNC-TN1400-2002-014.pdf:1.95MB

no abstracts in English

Microstructural Modeling of Compacted Sodium-Bentonite and Application of Unified Molecular Dynamics/Homogenization Analysis for Diffusion Process

Suzuki, Satoru; Fujishima, Atsushi; Ueno, Kenichi; Ichikawa, Yasuaki*; Kawamura, Katsuyuki*; Fujii, Naoki*; Shibata, Masahiro; Sato, Haruo; Kitayama, Kazumi*

Nendo Kagaku, 41(2), p.43 - 57, 2001/12

None

Information materials of research and development on geological isolation of radioactive waste

Kato, Tomoko; Fujishima, Atsushi; Ueno, Kenichi; ; Notoya, Shin; Sonobe, Hitoshi

JNC TN8450 2001-003, 205 Pages, 2001/01

JNC-TN8450-2001-003.pdf:77.1MB

We have compiled and refined the information materials to explain ENTRY (Engineering Scale Test and Research Facility) and QUALITY (Quantitative Assessment Radionuclide Migration Experimental Facility). These include information materials to show activities for research and development of radioactive waste disposal in Tokai Works such as panels of experimental equipments. This work was carried out by a working group in Waste Isolation Research Division, Waste Management and Fuel Cycle Research Center; Tokai Works in 19982000. We have developed database for above information materials including typical experimental equipments of ENTRY and QUALITY. In the future, it can be easily refind in case of reconstruction of the experimental equipments. This report presents the database including the experimental equipments and several pamphlet.

EXAFS analysis of Sm adsorbed on montmorillonite

Fujishima, Atsushi; Suzuki, Satoru; Ueno, Kenichi; ;

Spring-8 User Experiment Report No.5 (2000A), 0 Pages, 2001/00

None