Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Nagaishi, Ryuji; Kimura, Takaumi; Sinha, S. P.*
Molecular Physics, 101(7), p.1007 - 1014, 2003/01
Times Cited Count：20 Percentile：52.78(Chemistry, Physical)no abstracts in English
Yamaguchi, Tetsuji; Nakayama, Shinichi; Okamoto, Hisato
Radiochimica Acta, 90(12), p.863 - 868, 2003/01
Times Cited Count：4 Percentile：29.25(Chemistry, Inorganic & Nuclear)no abstracts in English
Yamaguchi, Tetsuji
Kyouto Daigaku Daigakuin Kougaku Kenkyuka Hakase Gakui Ronbun, 136 Pages, 2001/01
no abstracts in English
Nagasaki, Shinya*
JNC TJ8400 2000-004, 32 Pages, 2000/02
JNC-TJ8400-2000-004.pdf:0.69MB
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/K
mol, 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 NpO
CO
) on Na-montmorillonite were also examined by using same technique.
Ashida, Takashi; ; Sato, Haruo; ; Kitamura, Akira; Kawamura, Kazuhiro
JNC TN8400 99-083, 63 Pages, 1999/11
Studies on the chemical and migration behaviour of radionuclides were carried out in the Quantitative Assessment Radionuclide Migration Experimental Facility (QUALITY)for assuring the relaiability and for improving the propriety of data concerning nuclide migration used in the Second Progress Report for the geoloical disposal of high-level radioactive waste. Five studies for solubility, sorption and diffusion concerning nuclide migration were carried out. The overview of each study and the result is as follows: (1)Study on Effect of Carbonate on Np Solubility. Solubilities of Np(IV) were measured as functions of pH and carbonate concentration under reducing conditions. The obtained data could be well described by considering two hydroxo-carbonate complexes, and those stability constants were estimated and compared with the literature data. Consequently, the data obtained in this study were similar to the literature data. (2)Study on Effect of Carbonate on Np Sorption on Bentonite. Distribution coefficients (Kd) of Np(IV) on smectite were measured as a function of carbonate concentration. The obtained Kd values were approximately constant over the carbonate concentration (total carbon concentration 0.04-0.15M). The results of desorption tests by 1M KCl and HCl at the end of sorption experiments showed two different desorption behaviour; Np(IV) was well removed by HCl for the experiments in low carbonate concentration and by KCl for those in high carbonate concentration. (3)Distribution Coefficient Measurements for Cs, Pb and Cm on Rocks. Distribution Coefficients for Cs, Pb and Cm on Japanese major rocks (basalt, mudstone, sandstone, granodiorite and tuff) were measured as a function of ionic strength. The obtained Kd values were either the same orders or higher compared with data used to both fresh and saline groundwater systems in the Second Progress Report. This indicates that the Kd data used in the Second Progress Report are either proper or conservative. ...
*; Sato, Haruo; *
JNC TN8400 99-059, 59 Pages, 1999/10
Organic acids in groundwater are considered to form complexes and increase the solubility of radionuclides released from vitrified waste in a high-level radioactive waste (HLW) repository. To ivestigate whether the solubility of samarium (Sm) is influenced by organic substances, we measured Sm solubility in the presence of different organic substances and compared those values with results from thermodynamic predictions. Humic acid (Aldrich) is commercially available and soluble organic matter originated from bentonite were used as organic substances in this study. Consequently, the solubility of Sm showed a tendency to apparently increase with icreasing the concentration of humic acid, but in the presence of carbonate, thermodynamic predictions suggested that the dominant species are carbonate complexes and that the effect of organic substances are less than that of carbonate. Based on total organic carbon (TOC), the increase of Sm solubility measured with humic acid (Aldrich) was more significant than that in the case with soluble organic matter originated from bentonite. Since bentonite is presumed to include also simple organic matters of which stability constant for forming complexes is low, the effect of soluble organic matter originated from bentonite on the solubility of Sm is eonsidered to be less effective than that of humic acid (Aldrieh). Experimental values were compared with model prediction, propsed by Kim, based on data measured in a low pH region. Tentatively we calculated the increase in Sm solubility assuming complexation with humic acid. Trial calculations were carried out on the premise that the complexation reaction of metal ion with humic acid is based on neutralization process by 1-1 complexation. In this process, it was assumed that one metal ion coordinates with one unit of complexation sites which number of proton exchange sites is equal to ionic charge. Consequently, Kim's model indicated that carbonate complexes should be dominant ...
Yamaguchi, Tetsuji;
Journal of Contaminant Hydrology, 35, p.55 - 65, 1998/00
Times Cited Count：29 Percentile：63(Environmental Sciences)no abstracts in English
G.Meinrath*; Kato, Yoshiharu; Kimura, Takaumi; Yoshida, Zenko
Radiochimica Acta, 82, p.115 - 120, 1998/00
no abstracts in English
Yamaguchi, Tetsuji;
Hoshasei Haikibutsu Kenkyu, 3(1), p.49 - 61, 1996/08
no abstracts in English
Kimura, Takaumi; ; G.Meinrath*; Yoshida, Zenko; Choppin, G. R.*
JAERI-Conf 95-005, Vol.2, 0, p.473 - 485, 1995/03
no abstracts in English
Yamaguchi, Tetsuji; Sakamoto, Yoshiaki; Onuki, Toshihiko
Radiochimica Acta, 66-67, p.9 - 14, 1994/00
no abstracts in English
G.Meinrath*; Kimura, Takaumi
Journal of Alloys and Compounds, 202, p.89 - 93, 1993/00
Times Cited Count：35 Percentile：89.28(Chemistry, Physical)no abstracts in English
;
Journal of Inorganic and Nuclear Chemistry, 42, p.1301 - 1305, 1980/00
Times Cited Count：1 Percentile：5.8(Chemistry, Inorganic & Nuclear)no abstracts in English
;
Journal of Inorganic and Nuclear Chemistry, 41(4), p.507 - 511, 1979/00
Times Cited Count：6no abstracts in English
;
Journal of Inorganic and Nuclear Chemistry, 41(4), p.513 - 516, 1979/00
Times Cited Count：4no abstracts in English
;
Radiochem.Radioanal.Lett., 22(2), p.127 - 133, 1975/02
no abstracts in English
Kitamura, Akira; Ito, Miki*; Akagi, Yosuke*; Yoshida, Yasushi*
no journal, ,
Effect of carbonate concentration and redox conditions on uranium solubility under geological disposal conditions was investigated. The applicability of predicted values using thermodynamic database was verified.
