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Journal Articles

Alkaline dissolution behavior of montmorillonite under compacted condition

Sawaguchi, Takuma; Kadowaki, Mitsushi*; Yamaguchi, Tetsuji; Mukai, Masayuki; Tanaka, Tadao

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 20(2), p.71 - 78, 2013/12

The dissolution rate for montmorillonite under compacted condition was studied in order to evaluate long-term alteration behavior of bentonite buffer materials by highly alkaline groundwater. The dissolution rate of compacted montmorillonite was found to be larger than that of montmorillonite in compacted sand-bentonite mixtures at 130 $$^{circ}$$C, which revealed that the dissolution of montmorillonite was inhibited by decreasing the activity of hydroxide ions (${it $alpha$$_O$$_H$$^-$}$) in the compacted mixtures including accessory minerals such as silica. In order to provide reliability for the analysis of bentonite-alteration using a formula of dissolution rate of montmorillonite, it is important to quantify the decrease of ${it $alpha$$_O$$_H$$^-$}$ in the compacted mixtures and to formulate the dissolution rate of compacted montmorillonite.

Journal Articles

Changes in hydraulic conductivity of sand-bentonite mixtures accompanied by alkaline alteration

Yamaguchi, Tetsuji; Sawaguchi, Takuma; Tsukada, Manabu; Kadowaki, Mitsushi*; Tanaka, Tadao

Clay Minerals, 48(2), p.403 - 410, 2013/05

 Times Cited Count:7 Percentile:23.85(Chemistry, Physical)

Montmorillonite is the main constituent of bentonite clay buffer materials in radioactive waste repositories. Highly alkaline environments induced by cement based materials are likely to alter montmorillonite, and to deteriorate the physical and/or chemical properties of the buffer materials. The deterioration may cause variation in hydraulic conductivity of the buffer and induce major uncertainties in the radionuclide migration analysis. Empirical data on the variation of hydraulic conductivity are, however, scarce mainly because the alteration of compacted buffer materials, sand-bentonite mixture specimen, is extremely slow. In this study, laboratory experiments were performed to observe changes in hydraulic conductivity of sand-bentonite mixtures accompanied with their alkaline alteration using NaOH based solutions at 80-90 $$^{circ}$$C. Three types of experiments proved that the alkaline alteration of bentonite buffer can increase the hydraulic conductivity. The data obtained in this study are useful for verification of the code that will be used for assessing the alteration.

Oral presentation

Experimental research for long term evaluation on radioactive waste disposal; Progress in 2006

Tanaka, Tadao; Yamaguchi, Tetsuji; Iida, Yoshihisa; Kimura, Yuichiro; Taki, Hiroshi; Fujiwara, Takeshi; Ueda, Masato*; Mukai, Masayuki; Yamada, Fumika; Mizuno, Tsuyoshi; et al.

no journal, , 

no abstracts in English

Oral presentation

Experimental research for long term evaluation on radioactive waste disposal; Progress in 2007

Kimura, Yuichiro; Yamaguchi, Tetsuji; Iida, Yoshihisa; Otsuka, Ichiro; Taki, Hiroshi*; Mukai, Masayuki; Yamada, Fumika; Hoshino, Seiichi; Kadowaki, Mitsushi; Tanaka, Tadao; et al.

no journal, , 

no abstracts in English

Oral presentation

Dependence of OH$$^{-}$$ activity on the dissolution rate of compacted montmorillonite

Kadowaki, Mitsushi; Yamaguchi, Tetsuji; Mukai, Masayuki; Iida, Yoshihisa; Tanaka, Tadao; Nakayama, Shinichi

no journal, , 

no abstracts in English

Oral presentation

Experimental determination of hydraulic conductivity of bentonite under various exchangeable cation compositions and ionic strengths

Kadowaki, Mitsushi; Yamaguchi, Tetsuji; Mukai, Masayuki; Iida, Yoshihisa; Tanaka, Tadao

no journal, , 

no abstracts in English

Oral presentation

Experimental research for long-term assessment of radioactive waste disposal, Status at 2008; Outline

Iida, Yoshihisa; Usui, Hideo; Mitsumoto, Yoshibumi; Hoshino, Seiichi; Kadowaki, Mitsushi; Mukai, Masayuki; Yamaguchi, Tetsuji; Tanaka, Tadao

no journal, , 

no abstracts in English

Oral presentation

Experimental research for long-term assessment of radioactive waste disposal, Status at 2008; Studies on alteration of cement and bentonite

Hoshino, Seiichi; Kadowaki, Mitsushi; Yamada, Fumika*; Mukai, Masayuki; Iida, Yoshihisa; Yamaguchi, Tetsuji; Tanaka, Tadao; Nakayama, Shinichi

no journal, , 

no abstracts in English

Oral presentation

Verification of a reactive transport model for long-term alteration of cement-clay systems based on laboratory experiments and in situ observations

Yamaguchi, Tetsuji; Mitsumoto, Yoshibumi; Kadowaki, Mitsushi; Hoshino, Seiichi; Maeda, Toshikatsu; Tanaka, Tadao; Nakayama, Shinichi; Marsal, F.*; Pellegrini, D.*

no journal, , 

It is important to assess long-term alteration of engineered barrier composed of bentonite and cement for the safety assessment of radioactive waste disposal. A mineral model for bentonite-cement-seawater systems and a hydraulic conductivity model for bentonite buffer materials were developed and verified by comparing results of the model calculations with experimental observations. Changes in mineralogy of bentonite buffer materials and accompanying changes in the hydraulic conductivity over 10,000 y were calculated to identify key issues in the long-term alteration analysis. The calculation showed that the temperature, the slow kinetics of the dissolution of montmorillonite, the diffusive mass transfer and the initial (1000 y) mineralogical changes were identified as the key issues. The salinity of the groundwater was identifies as another key issue, which has both positive and negative effects on the hydraulic conductivity.

Oral presentation

Dependence of the dissolution rate of compacted montmorillonite on OH$$^{-}$$ activity under highly alkaline conditions

Sawaguchi, Takuma; Kadowaki, Mitsushi*; Mukai, Masayuki; Tsukada, Manabu; Maeda, Toshikatsu; Tanaka, Tadao

no journal, , 

no abstracts in English

Oral presentation

Development on evaluation method for hydraulic conductivity of compacted bentonite under alkaline conditions, 1; Outline of long-term hydraulic conductivity experiments

Tsukada, Manabu; Kadowaki, Mitsushi*; Mukai, Masayuki; Sawaguchi, Takuma; Kataoka, Masaharu; Maeda, Toshikatsu; Tanaka, Tadao

no journal, , 

no abstracts in English

Oral presentation

Development on evaluation method for hydraulic conductivity of compacted bentonite under alkaline conditions, 2; Analysis using coupled mass-transport/chemical-reaction code

Kataoka, Masaharu; Mukai, Masayuki; Sawaguchi, Takuma; Tsukada, Manabu; Kadowaki, Mitsushi*; Maeda, Toshikatsu; Tanaka, Tadao

no journal, , 

no abstracts in English

Oral presentation

Study on hydraulic conductivity of conpacted bentonite considered with alkaline alteration

Kataoka, Masaharu; Tsukada, Manabu; Mukai, Masayuki; Sawaguchi, Takuma; Kadowaki, Mitsushi*; Maeda, Toshikatsu; Tanaka, Tadao

no journal, , 

no abstracts in English

Oral presentation

Study on evaluation for long-term alteration behavior of bentonite buffer materials

Sawaguchi, Takuma; Kadowaki, Mitsushi*; Mukai, Masayuki; Tsukada, Manabu; Kataoka, Masaharu; Maeda, Toshikatsu; Tanaka, Tadao

no journal, , 

no abstracts in English

Oral presentation

Study on hydraulic conductivity of compacted bentonite considered with Long-term degradation

Kataoka, Masaharu; Tsukada, Manabu; Mukai, Masayuki; Sawaguchi, Takuma; Kadowaki, Mitsushi*; Maeda, Toshikatsu; Tanaka, Tadao

no journal, , 

no abstracts in English

15 (Records 1-15 displayed on this page)
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