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Hemmi, Ko
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 23(1), P. 113, 2016/06
no abstracts in English
, Na, I
and HTO in granodiorite; Laboratory-scale results and their extrapolation to the in situ conditionTachi, Yukio; Ebina, Takanori*; Takeda, Chizuko*; Saito, Toshihiko*; Takahashi, Hiroaki*; Ouchi, Yuji*; Martin, A. J.*
Journal of Contaminant Hydrology, 179, p.10 - 24, 2015/08
Times Cited Count：29 Percentile：73.48(Environmental Sciences)Matrix diffusion and sorption are important processes in the assessment of radionuclide transport in crystalline rocks. Diffusion and sorption parameters for Cs, Na, I and HTO were determined by through-diffusion and batch sorption experiments using granodiorite samples from the Grimsel Test Site, Switzerland. The De values were in the order Cs, Na, HTO, I. The capacity factor and Kd values show the same trends. The dual depth profiles for Cs and Na can be interpreted by a near-surface Kd increment. The microscopic analysis indicated that this is caused by high porosity and sorption capacities in disturbed biotite minerals on the sample surface. The Kd values derived from the dual profiles are likely to correspond to Kd dependence on the grain sizes of crushed samples in the batch experiments. The results of the in situ LTD experiments were interpreted reasonably well by using transport parameters derived from laboratory data and extrapolating them to in situ conditions.
Hemmi, Ko; Yamaguchi, Tetsuji; Iida, Yoshihisa
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 22(1), p.3 - 10, 2015/06
Iodine and tin are important elements in performance assessment of geological disposal of radioactive wastes. Sorption experiments of iodine were carried out under varying nitrate concentration with a range of 0 to 5 mol dm
at neutral pH range in order to determine the distribution coefficient of iodine was zero or non-zero value. The experimental results with estimated statistical errors showed non-zero values for tuffaceous sandstone except for NaNO
concentration 0.5 mol dm. Non-zero values were also obtained under NaNO concentrations higher than 0.5 mol dm for granodiorite. Sorption experiments of tin were carried out at high pH range in order to check whether the distribution coefficient of tin decreases significantly with pH as a result of formation of anionic hydrolysis species of tin. The distribution coefficients of tin on granodiorite decreased from 9.79
10
m
kg
at pH10.4 to 2.4610 m kg at pH12.4. The distribution coefficient of tin on tuffaceous sandstone was about one order of magnitude higher (about 210 m kg) than that of granodiorite at pH around 12.4.
Kato, Hiroshige*; Sato, Mitsuyoshi*; Owada, Hitoshi*; Mihara, Morihiro;
JNC TN8430 2000-008, 53 Pages, 2000/05
Cementitious materials will be used in TRU waste disposal repository. In such cases, it is considered that the migration of alkaline leachates from cementitious materials, so called high pH plume, will cause dissolution of rock and precipitation of secondary minerals. In addition, the high pH plume will move along the flow of groundwater, so it is predicted that rock formation and components of high pH groundwater vary with time and space. However, time and spatial dependence of the variations of secondary minerals and groundwater components has not been clarified. In order to acquire the data of variations of secondary minerals and groundwater components, we carried out the rock alteration experiments with column method. The crushed granodiorite was filled into 4 meters length column (
3.7 cm) and artificial cement leachate (pH=13.3; Na=0,1 mol/l, K=0.1 mol/l, Ca=0.002 mol/l) was streamed at flow rates of 0.1 ml/min for 7 months at 80
C. As the result, secondary minerals confirmed on the rock were calcite and C-S-H at upstream of column and C-S-H at mid-downstream. The pH value of the fluid dominated by Na and K did not be decreased by reaction with the rock. In this study, the data relating to the effect of high pH plume on rock over the long term was acquired.
*; Takahashi, Nao*
JNC TJ7440 2000-014, 40 Pages, 2000/02
JNC-TJ7440-2000-014.pdf:17.73MB
no abstracts in English
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. ...
Oda, Chie; Ikeda, Takao*; Shibata, Masahiro
JNC TN8400 99-073, 112 Pages, 1999/11
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. 
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
10
[ml/g], 10
10
[ml/g] and 10 10[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
[m
/sec] and l0
[m/sec] for dry densities of 0.4[g/cm] and 1.0[g/cm], 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
reported by Amaya et al. (1997), however, the derived Kd values were lower than that measured from the batch-type sorption experiments.
Sato, Haruo
JNC TN8400 99-061, 9 Pages, 1999/10
The porosities and dry densities for rock samples sampled from a fractured zone (fracture type C: composed of intact ganodiorite, altered ganodiorite and fracture fillings) at the Kamaishi mine were obtained by a water saturation (intrusion) method as input parameters for nuclide migration analysis in performance assessment of the geological disposal of high-level radioactive waste. Consequently, the average porosity, 8.6
0.43% was higher than those of fracture fillings, altered garnodiorite and intact ganodiorite composing fracture type B with a single fracture taken from the Kamaishi mine so far. While, the average dry density, 2.430.0089 Mg
m, was lower than those of rocks composing the fracture type B. Based on this, it is predicted that radionuclides are the easiest to migrate in the fracture zone.
Sasamoto, Hiroshi; Yui, Mikazu; Arthur, R. C,*
JNC TN8400 99-033, 153 Pages, 1999/07
The results of hydrochemical investigations of groundwaters in the Kurihashi granodiorite at JNC's Kamaishi in-situ tests site indicate that these solutions are: (1)meteoric in origin, (2)chemically reducing (at depths greater than a few hundreds meters), (3)relatively young [residence times in the Kurihashi granodiorite generally less than about 40 years, but groundwaters older than several thousand years BP (before present) are also indicated by preliminary carbon-14 dating of samples obtained from the KH-1 borehole], (4)Ca-HCO type solutions near the surface, changing to Na-HCO type groundwaters with increasing depth. The evolution of groundwater compositions in the Kurihashi granodiorite is modeled assuming local equilibrium for selected mineral-fluid reactions, taking into account the rainwater origin of these solutions. Results suggest it is possible to interpret approximately the "real" groundwater chemistry (i.e., pH, Eh, total dissolved concentrations of Si, Na, Ca, K, AI, carbonate and sulfate) in the Kurihashi granodiorite if the following assumptions are adopted: (1)CO concentration in the gas phase contacting pore solutions in the overlying soil zone = 10 bar, (2)minerals in the rock zone that control the solubility of respective elements in the groundwater include; chalcedony (Si), albite (Na), kaolinite (Al), calcite (Ca and carbonate), microcline (K) and pyrite (Eh and sulfate). Discussions with international experts suggest a systematic approach utilizing reaction-path models of irreversible water-rock interactions in open systems may be needed to more realistically model groundwater evolution at the Kamaishi test site. Detailed information characterizing certain site properties (e.g., fracture mineralogy) may be required to adequately constrain such models, however.
; ; Sato, Haruo; Shibata, Masahiro
JNC TN8400 99-088, 58 Pages, 1999/06
Sorption and diffusion behavior of palladium, which has been identified as one of the hazardous radionuclides in performance assessment of HLW disposal, in bentonite, granodiorite and tuff was studied in order to make reliable data set for the performance assessment. Sorption experiments of Pd on bentonite, granodiorite and tuff were conducted as functions of pH, ionic strength and liquid to solid ratio by batch method under aerobic conditions at room temperature. The distribution coefficients (K
) of Pd on these solids were almost in the range of 10 to 10 m/kg and were in the order of bentonite 
granodiorite 
tuff. The sorption trends with change in PH, ionic strength and liquid to solid ratio are very similar between three solids. The K values were the highest at pH5 and decreased with increasing pH between 5 and 11. The effect of ionic strength on K was not found in a range of 10 to 10, but K values increased with increasing liquid to solid ratio. The width of variation in K was one order of magnitude in a liquid to solid ratio of 0.1 to 1 m/kg. Sorption behavior of Pd is different from that of divalent metal ions such as Ni and Co etc. and chemical analogy may be inappropriate. The dominant aqueous species of Pd in the expermental conditions studied is estimated to be neutral species, Pd(OH)(aq) by the thermodynamic calculations. The K values of Pd on three solids were relatively high and uncharged complexes may be more strongly sorbed. The pH dependency of K values suggests that Pd sorption is most likely to be occurring onto positively charged S-OH type site which are progressively removed (to from SOH and SO
sites) at higher pH values. Diffusion behavior of Pd in bentonite was also studied by in-diffusion method as a function of dry density. The D
values obtained based on the instantaneous planar source model were in the orders of ...
Ueta, Shinzo*
PNC TJ1211 98-002, 46 Pages, 1998/02
None
Ueta, Shinzo*
PNC TJ1211 98-001, 824 Pages, 1998/02
None
Sato, Haruo
PNC TN8410 97-202, 205 Pages, 1998/01
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 2000 kgm under ambient aerobic conditions at room temperature (20 23C), 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 ...
*; Shingu, Kazuki*; Takahashi, Eiichiro*; Nakajima, Toshihide*; Yamashita, Mitsugu*; *; *
PNC TJ7187 97-002, 586 Pages, 1997/11
None
Yoneda, Yoshihiro*; Takahara, Hiroyuki*; Nakamura, Naoaki*; Akiyama, Shinsuke*; Moriya, Toshifumi*; Negi, Tateyuki*
PNC TJ1380 97-001, 1338 Pages, 1997/03
None
; Koide, Kaoru*; *; Yoshida, Eiichi; *; ; Fujita, Tomoo
PNC TN1410 97-038, 307 Pages, 1996/04
no abstracts in English
