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JAEA Reports

Activation energy of diffusivities for deuterated water in compacted sodium-bentonite; Through-diffusion experiment and molecular dynamics simulation

; Sato, Haruo; Ishidera, Takamitsu; Fujii, Naoki*; Kawamura, Katsuyuki*

JNC-TN8400 2001-031, 44 Pages, 2002/05

JNC-TN8400-2001-031.pdf:1.58MB

In order to quantify effect of temperature on diffusivity of deuterated water (HDO) in compacted sodium-bentonite, through-diffusion experiments were conducted at elevated tempemture from 298 to 333 K. Kunipia F (Na-montmorillonite content $$>$$ 98 wt. %; Kunimine Industly Co.) was compacted to a dry density of 0.9 and l.35 Mg/m$$^{3}$$. Since smectite flakes were perpendicularly oriented to a direction of compaction, anisotropy of diffusivity was investigated parallel and normal to the preferred orientation of smectite. Effective diffusion coeficient D$$_{e}$$ of HDO was larger for a diffusional direction parallel to the preferred orientation than normal to that for both dry densities. These results well agreed to the previously reported ones for tritiated water. Activation energies of D$$_{e}$$ in compacted bentonite increased with increasing dry density in the range of 19 - 25 kJ/mol which was slightly larger than that in bulk water (18 kJ/mol). This relationship can be considered to be due to both the pore structure development and high activation energy of water (18-23 kJ/mol) in the vicinity of smectite surface (within 2 nm) on the basis of molecular dynamics simulations.

Journal Articles

Study on uptake of europium by the thin film of apatite and smectite mixture using RBS and micro-PIXE

Onuki, Toshihiko; Kozai, Naofumi; Samadfam, M.; Yamamoto, Shunya; Narumi, Kazumasa; Naramoto, Hiroshi; Kamiya, Tomihiro; Sakai, Takuro; Murakami, Takashi*

Nuclear Instruments and Methods in Physics Research B, 181(1-4), p.644 - 648, 2001/07

 Times Cited Count:4 Percentile:64.97(Instruments & Instrumentation)

no abstracts in English

JAEA Reports

Study of vibrational spectra of interlayer water in Na-Smectite by means of molecular dynamics simulations

; Kawamura, Katsuyuki*

JNC-TN8400 2001-005, 41 Pages, 2001/04

JNC-TN8400-2001-005.pdf:1.1MB

A correlation between molecular structure and a vibrational spectrum of interlayer water in Na-smectite was investigated by means of Molecular Dymamics (MDs) simulations. Detailed comparison of simulation results with IR spectroscopic observations for the water-smectite system indicated good agreement. Internal vibrational spectra of water were obtained by the Fourier transformation of velocty auto-correlation function of hydrogen atom. A stretching vibrational spectrum of interlayer water consisted of a broad band with a peak top around 3400cm$$^{-1}$$ and a sharp peak around 3650 to 3700cm$$^{-1}$$. The fomer broad band was assigned to O-H vibrations between water molecules as bulk water, while the latter band was attributed to O-H ones oriented to siloxane surface through hydrogen bonding. The hydrogen bond distance, determined as the shortest O-O distance by the radial distribution function (RDF), revealed that hydrogen bond distance between water and siloxane surface (O$$_{H2O}$$-O$$_{clay}$$ $$>$$ 3.0 $AA )was larger than that between water molecules (O$_{H2O}$$-O$$_{H2O}$$ = ca. 2.8 AA ). These results suggested that interaction between water molecule and siloxane surface weaker than that between water molecules, although they were forced to be oriented.

JAEA Reports

None

; *; ; *

JNC-TY6400 2000-013, 102 Pages, 2000/02

JNC-TY6400-2000-013.pdf:2.45MB

None

JAEA Reports

ExperimentaI studies for sorption behavior of Tin on bentonite and rocks, and diffusion behavior of Tin in compacted bentonite

Oda, Chie; Ikeda, Takao*; Shibata, Masahiro

JNC-TN8400 99-073, 112 Pages, 1999/11

JNC-TN8400-99-073.pdf:2.79MB

In the safety assessment for geological disposal of high-level radioactive wastes (HLW), distribution coefficients (Kd) and diffusion coefficients of radionuclides are used to estimate the migration of radionuclides in a near-field of repository. $$^{126}$$Sn is one of the important nuclides for the safety assessment in Japan and its behavior under reopsitory conditions has not been understood. This report provides the experimental informations for the sorption of Sn on bentonite, tuff and granodiorite, and the diffusion of Sn in a compacted bentonite. The Kd values of Sn on bentonite, tuff and granodiorite were determined by the batch-type sorption experiments as l0$$^{3}$$$$sim$$10$$^{6}$$[ml/g], 10$$^{4}$$$$sim$$10$$^{5}$$[ml/g] and 10$$^{3}$$ $$sim$$ 10$$^{5}$$[ml/g], respectively. The sequential extraction experiments for adsorbed Sn on bentonite were also performed to investigate its desorption behavior. These experimental results indicated that the mechanisms of sorprion onto bentonite were dominated by the sorption reactions on smectite and pyrite and consisted of reversible and irreversible sorption on solid and stable fixation in solid. On the other hands, the apparent diffusion coefficients (Da) in compacted bentonite were measured by the diffusion experiments as 10$$^{-13}$$[m$$^{2}$$/sec] and l0$$^{-14}$$ [m$$^{2}$$/sec] for dry densities of 0.4[g/cm$$^{3}$$] and 1.0[g/cm$$^{3}$$], respectively. Moreover, the Kd values in compacted bentonite were calculated according to the relationship with the measured Da values, and the solubilities in the porewaters of compacted bentonite were calculated by use of the calculated Kd and the obtained diffusion plofiles. It is found that the derived solubilities almost agreed with the solubiliies of amorphis SnO$$_{2}$$ reported by Amaya et al. (1997), however, the derived Kd values were lower than that measured from the batch-type sorption experiments.

JAEA Reports

None

*

PNC-TJ1626 98-001, 123 Pages, 1998/03

PNC-TJ1626-98-001.pdf:3.51MB

None

JAEA Reports

None

Futakuchi, Katsuhito*; Sakuramoto, Yuji*; *; *; *; Hashimoto, Shuji*

PNC-TJ1308 98-001, 103 Pages, 1998/02

PNC-TJ1308-98-001.pdf:19.05MB

None

JAEA Reports

A Study on nuclide migration in buffer materials and rocks for geological disposal of radioactive waste

Sato, Haruo

PNC-TN8410 97-202, 205 Pages, 1998/01

PNC-TN8410-97-202.pdf:14.14MB

This thesis summarizes the results investigated in order to establish a basic theory on the predictive method of diffusion coefficients of nuclides in compacted sodium bentonite which is a candidate buffer material and in representative rocks for the geological disposal of radioactive waste by measuring the pore structural factors of the compacted bentonite and rocks such as porosity and tortuosity, measuring diffusion coefficients of nuclides in the bentonite and rocks, acquiring basic data on diffusion and developing diffusion models which can quantitatively predict nuclide migration in long-term. This consists of 7 chapters. Chapter 1 is the introduction, in which conventional studies on nuclide migration in buffer materials and rocks for the geological disposal of radioactive waste carried out to date are reviewed, and those problems are summarized as well as the objectives of this study are described. Besides, the difinition of geological disposal is explained. In Chapter 2, it is described on non-steady state diffusion of HTO, Sr-90, Tc-99, I-129, Cs-137, Np-237, Am-241 and Pu in purified sodium bentonite, Kunipia-F, in which the rate of constituent Na-smectite was raised approximately 100wt%. In-diffusion experiments were carried out in a range of bentonite densities of 200 $$sim$$ 2000 kg$$cdot$$m$$^{-3}$$ under ambient aerobic conditions at room temperature (20 $$sim$$ 23$$^{circ}$$C), and apparent diffusion coefficients (Da) were obtained. The apparent diffusion coefficients decreased with increasing dry density of bentonite. It was quantitatively indicated from diffusion experiments using HTO that these Da values include the effect of geometric retardation such as the tortuosity factor of compacted bentonite. It was experimentally clarified that Da is not affected by diffusion time based on diffusion experiments for different experimental periods using Sr and Cs. Moreover, it was also experimentally clarified that Da is not affected by tracer ...

Journal Articles

Liferature review; Behavior of smectites in high pH conditions

Sato, Tsutomu

Sumekutaito Kenkyukai Kaihou, 8(2), p.44 - 46, 1998/00

no abstracts in English

Journal Articles

Structure and characteristics of adsorbed water on smectites

Sato, Tsutomu

Sumekutaito Kenkyukai Kaihou, 7(2), p.2 - 13, 1997/11

no abstracts in English

Journal Articles

Neutron diffraction studies of smectite

Sato, Tsutomu

Sumekutaito Kenkyukai Kaihou, 7(2), p.39 - 41, 1997/00

no abstracts in English

Journal Articles

Change in layer charge of smectites and smectite layers in illite/smectite during diagenetic alteration

Sato, Tsutomu; Murakami, Takashi*; Watanabe, Takashi*

Clays and Clay Minerals, 44(4), p.460 - 469, 1996/00

 Times Cited Count:33 Percentile:28.54(Chemistry, Physical)

no abstracts in English

Journal Articles

A Study of specific sorption of neptunium(V) on smectite in low pH solution

Kozai, Naofumi; Onuki, Toshihiko; Matsumoto, Junko; Bamba, Tsunetaka; *

Radiochimica Acta, 75(3), p.149 - 158, 1996/00

no abstracts in English

Journal Articles

Effect of crystallochemistry of starting materials on the rate of smectite to illite reaction

Sato, Tsutomu; Murakami, Takashi*; Isobe, Hiroshi; Onuki, Toshihiko

Mater. Res. Soc. Symp. Proc., Vol. 353, 0, p.239 - 246, 1995/00

no abstracts in English

Journal Articles

Literature review; Heterogeneity of smectite: Monomineralic solid-solutions or multiphase mixtures?

Sato, Tsutomu

SMECTITE, 4(1), p.48 - 51, 1994/05

no abstracts in English

Journal Articles

Variety and variability of bentonites as buffer materials in radioactive waste disposal

Sato, Tsutomu

Nippon Genshiryoku Gakkai-Shi, 36(5), p.405 - 412, 1994/00

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Effect of calcium ion on sorption of neptunium by smectite

Kozai, Naofumi; Onuki, Toshihiko; Muraoka, Susumu

Nippon Genshiryoku Gakkai-Shi, 36(10), p.955 - 957, 1994/00

 Times Cited Count:2 Percentile:71.03(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Redistribution of strontium and cesium during alteration of smectite to illite

Onuki, Toshihiko; Murakami, Takashi; Sato, Tsutomu; Isobe, Hiroshi

Radiochimica Acta, 66-67, p.323 - 326, 1994/00

no abstracts in English

Journal Articles

Sorption characteristics of radioactive cesium and strontium on smectite

Onuki, Toshihiko; Kozai, Naofumi

Radiochimica Acta, 66-67, p.327 - 331, 1994/00

no abstracts in English

Journal Articles

Sorption characteristics of neptunium by sodium-smectite

Kozai, Naofumi; Onuki, Toshihiko; Muraoka, Susumu

Journal of Nuclear Science and Technology, 30(11), p.1153 - 1159, 1993/11

 Times Cited Count:26 Percentile:9.83(Nuclear Science & Technology)

no abstracts in English

29 (Records 1-20 displayed on this page)