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Mei, H.; Aoyagi, Noboru; Saito, Takumi*; Tanaka, Kazuya; Sugiura, Yuki; Tachi, Yukio
Applied Geochemistry, 162, p.105926_1 - 105926_8, 2024/02
Iida, Yoshihisa; Barr, L.; Yamaguchi, Tetsuji; Hemmi, Ko
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 23(1), p.3 - 8, 2016/06
Thorium (Th)-229 is one of the important radionuclides for the performance assessment calculations for high-level radioactive waste repositories. The sorption behavior of Th onto montmorillonite and illite were investigated by batch sorption experiments. Experiments were carried out under variable pH and carbonate concentrations. The sorbability of montmorillonite was higher than that of illite. Distribution coefficients, (m kg), decreased with increased carbonate concentrations and showed the minimal value at around pH 10. The sorption behaviors of Th were analyzed by the non-electrostatic surface complex model with PHREEQC computer program. The model calculations were able to explain the experimental results reasonably well. The decreases of was likely due to the stabilization of aqueous species by hydroxo-carbonate complexations in the solutions.
Futakuchi, Katsuhito*; Hashimoto, Shuji*; Sakuramoto, Yuji*; ; Kamei, Gento
JNC TN8400 2001-007, 52 Pages, 2001/04
As a natural analogue, the authors investigted a Tertiary argillaceous bed and a Quarternary hypabyssal rock (porphyrite) which intruded into the argillaceous rock, distributed in the Nishikubiki district of Niigata prefecture in Japan. We examined the variation of clay mineral species in the argillaceous rock surrounding the intrusive rock and carried out thermal analyses for the argillaceous rock based on the coolig history of the intrusive rock. The predominant clay mineral varied from montmorillonite to illite through illite/montmorillonite interlayers with approaching to the intrusive rock. The thermal analyses indicated that the temperature descended from 270 to 15 C during the 7.5 10 years at alocalty of argillaceous rock containing 75% illite in the interlayers. On the assumption that the alteration from montmorillonite to illite was regarded as a first-order reaction, we evaluated the apparent activation energy based on the thermal condition mentioned above; about 103 kJ/mol was obtained for this illitization. This was within the range of values reported previously by laboratory experiments and/or examinations of natural illitizations.
Imai, Jun*
JNC TJ8400 2000-008, 196 Pages, 2000/02
The objective of this research is to make clear long-term alteration processes of bentonite contacting with concrete under a repository condition for radioactive waste. The Uzu tunnel in yamagata prefecture in Japan, constructed during the term of December of 1963 to July 1967, was selected as an appropriate natural analogue: the tunnel wall was made of portland cement and which has been contacting with a bentonite bed during 32 years. Sample analyses indicated that the original bentonite was Na-type and it changed to Ca-type in the range of a few millimeters from the contact. Although a Ca leaching was also observed from the concrete near the contact, neither transformation to zeolite nor to illite was recognized. On the other hand, sulfur increased and ettringite (3CaO AlO 3CaSO4 32HO) was recognized in the concrete within the depth about 30 mm from the contact.
Nagasaki, Shinya*
JNC TJ8400 2000-004, 32 Pages, 2000/02
Equilibrium and kinetics of sorption of NpO on illite were investigated at pH = 6 by using the differential pulse anodic stripping voltammetry method and the spectroscopic method, respectively. It was found that the sorption isotherm obtained was fitted better by the Langmuir-Freundlich type equation than by the Langmuir equation. The heterogeneity coefficient was 0.89 0.05 and the half width at half maximum (HWHM) of affinity spectrum was 0.19 log unit, indicating that the surfacc of illite used has a low degree of heterogeneity. The kinetic spectra indicated that the sorption of NpO occurs only at the outer surfacc. The mean HWHM of the kinetic spectra was 0.18 log unit. This also proves that the sorption kinetics of NpO on the illite used is controlled by the same heterogeneity of the sorption sites. From the dependence of mean rate constants on temperature, a mean apparent activation enthalpy and a mean apparent activation entropy were evaluated at 373 kJ/mol and - 69 7 J/Kmol, respectively. This value of enthalpy suggests that the sorption is not controlled by diffusion through the hydrodynamic film around the illite. Equilibrium and kinetics of sorption of NpO and Np(V) carbonate complexes (mainly NpOCO) on Na-montmorillonite were also examined by using same technique.
Tanaka, Toru*; Wakahara, Akihiro*; Yoshida, Akira*; Oshima, Takeshi; Ito, Hisayoshi; Okada, Sohei
Journal of Applied Physics, 87(7), p.3283 - 3286, 2000/01
Times Cited Count:11 Percentile:46.85(Physics, Applied)no abstracts in English
Sato, Tsutomu; Murakami, Takashi*; Watanabe, Takashi*
Clays and Clay Minerals, 44(4), p.460 - 469, 1996/00
Times Cited Count:37 Percentile:75.36(Chemistry, Physical)no abstracts in English
Sato, Tsutomu; Murakami, Takashi*; Isobe, Hiroshi; Onuki, Toshihiko
Materials Research Society Symposium Proceedings, Vol.353, 0, p.239 - 246, 1995/00
no abstracts in English
Onuki, Toshihiko; Murakami, Takashi; Sato, Tsutomu; Isobe, Hiroshi
Radiochimica Acta, 66-67, p.323 - 326, 1994/00
no abstracts in English
Sato, Tsutomu
SMECTITE, 3(1), p.39 - 41, 1993/05
no abstracts in English
Murakami, Takashi; Sato, Tsutomu; Watanabe, Takashi*
American Mineralogist, 78(3), p.465 - 468, 1993/00
no abstracts in English
Onuki, Toshihiko; Murakami, Takashi; Sato, Tsutomu; Isobe, Hiroshi
Nihon Genshiryoku Gakkai-Shi, 34(12), p.1139 - 1142, 1992/12
Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)no abstracts in English