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Kobayashi, Taishi*; Nakajima, Shogo*; Motokawa, Ryuhei; Matsumura, Daiju; Saito, Takumi*; Sasaki, Takayuki*
Langmuir, 35(24), p.7995 - 8006, 2019/06
Times Cited Count：5 Percentile：22.5(Chemistry, Multidisciplinary)Sasamoto, Hiroshi; Onda, Shingo*
Geological Society Special Publications, 482, 13 Pages, 2018/09
Times Cited Count：2 Percentile：21.58(Geology)Colloid concentration is an important parameter in models of colloid-facilitated transport. The purpose of present study is to characterize colloid concentrations and colloid stability in natural groundwater from the Horonobe Underground Research Laboratory (URL) as for development of a procedure. The particle sizes of colloids in groundwaters from the Horonobe URL range from several nm to ca. 500 nm, with a mode particle size of ca. 120 nm. Evaluation of colloid stability by DLVO theory suggests that larger colloids (i.e., 
100 nm in diameter) would be more stable than smaller colloids in some groundwaters. The estimated colloid particle concentrations ranged from 2.33
10
to 1.1210
pt/mL, and mass concentrations were estimated to range from 45 to 1540 
g/L for diameters greater than 100 nm. Colloids in Horonobe groundwaters appear to be less stable, with a moderate potential for transport, than colloids investigated in similar international studies. This reduced stability may be due to relatively higher ionic strengths and moderate dissolved organic concentrations in Horonobe groundwaters compared to their international counterparts.
Aosai, Daisuke*; Saeki, Daisuke*; Iwatsuki, Teruki; Matsuyama, Hideto*
Colloids and Surfaces A; Physicochemical and Engineering Aspects, 495, p.68 - 78, 2016/04
Times Cited Count：1 Percentile：1.69(Chemistry, Physical)The transport of radionuclides by organic colloids in deep groundwater is one of the important issues for the geological disposal of high-level radioactive waste. Because of their low concentration, it is difficult to directly analyze organic colloids in deep groundwater. In this study, hydrodynamic conditions were optimized, and surfaces of nanofiltration membranes were modified using a cationic phosphorylcholine polymer for preventing membrane fouling. Deep groundwater, obtained at the Mizunami Underground Research Laboratory in Japan, was condensed. The recovery yield of the organic colloids in the deep groundwater condensation test at 5-fold condensation was improved from 62% to 92% by the optimized hydrodynamic conditions and membrane surface modification for prevention of membrane fouling. The composition of organic colloids in the condensates was analyzed using pyrolysis gas chromatography coupled with mass spectrometry.
Aosai, Daisuke*; Saeki, Daisuke*; Iwatsuki, Teruki; Matsuyama, Hideto*
Colloids and Surfaces A; Physicochemical and Engineering Aspects, 485, p.55 - 62, 2015/11
Times Cited Count：5 Percentile：11.59(Chemistry, Physical)To analyze organic colloids in deep groundwater, concentration techniques using adsorption resins and reverse osmosis membranes have been widely applied, because their concentrations in deep groundwater are very low and detection of the organic colloids in raw groundwater is difficult. However, these techniques have respective disadvantages such as chemical disturbance and membrane fouling caused by cations. To overcome their disadvantages, we propose a new concentration method using nanofiltration membranes to concentrate organic colloids rapidly without chemical disturbance and to selectively remove monovalent and divalent ions, which may cause inorganic and/or organic fouling. Concentration performance of the NF and RO membranes for aqueous solutions for humic acids was evaluated using a laboratory-scale membrane test unit. The time course of permeate flux and concentration of humic acids were measured. These membranes were applied to the concentration of actual groundwater.
Saito, Takumi; Hamamoto, Takafumi*; Mizuno, Takashi; Iwatsuki, Teruki; Tanaka, Satoru*
Journal of Analytical Atomic Spectrometry, 30(6), p.1229 - 1236, 2015/06
Times Cited Count：13 Percentile：60.95(Chemistry, Analytical)Size distribution and elemental compositions of colloids in granitic and sedimentary deep groundwater was determined by flow field flow fractionation (Fl-FFF) combined with ICP-MS. In the granitic groundwater organic colloids and various inorganic elements were found in limited size ranges (
10 nm and 140 nm). The presence of different types of organic colloids was suggested in this groundwater. Most of the inorganic elements exhibited similar size distributions at 10 nm, which were largely overlapped with organic colloids rich in fluorophores. In the sedimentary groundwater small organic and probably inorganic colloids were found at 5 nm together with relatively large inorganic colloids. Organic colloids in this groundwater were homogeneous in terms of their sizes and the compositions of chromohores and fluorophores. The size distribution of inorganic elements depended on their types, indicating the presence of different host colloidal phases for them.
Aosai, Daisuke*; Yamamoto, Yuhei*; Mizuno, Takashi; Ishigami, Toru*; Matsuyama, Hideto*
Colloids and Surfaces A; Physicochemical and Engineering Aspects, 461, p.279 - 286, 2014/11
Times Cited Count：10 Percentile：25(Chemistry, Physical)In studies of colloids in deep groundwater, a serious problem exists because the properties of the colloids are influenced by changes in the chemistry of groundwater upon exposure to the atmosphere and pressure release during sampling. Then, ultrafiltration technique, while maintaining in situ hydrochemical conditions was developed. As the result of the investigation using the method at the Mizunami underground Research Laboratory (MIU), different types of colloids consisting of inorganic and organic substances were observed and complex formation between the colloids and REEs was suggested. Furthermore, characteristic partitioning of REEs depending on colloids size was observed in complex natural environments without chemical disturbance. The current findings are useful for understanding migration of radionuclides.
Mukai, Masayuki; Tanaka, Tadao; Yukawa, Kazuhiko; Suryantoro*
Genshiryoku Bakkuendo Kenkyu, 12(1-2), p.41 - 51, 2006/03
To evaluate radionuclides migration through geologic media coexistent with colloids in groundwater, a model has been coded. To evaluate an applicability of four models to colloid transport through porous media, breakthrough curves (BTCs) from column experiments using sand and reddish soil have been analyzed. Instantaneous equilibrium model could not explain both timings of breakthrough and reach to C
/C
=1 concurrenyly, however 1st order kinetic reaction model successfully simulate them well. BTCs from the reddish soil column have a particular feature that shows step-wise rising pattern in response to alternately inflow of colloid. Both the instantaneous equilibrium, the 1st order kinetic reaction and filtration models could not simulate this feature, however a 1st order kinetic reaction with filtration capacity model reasonably simulates the feature. The model for colloid transport, given an important role as a part of colloidal migration model of radionuclide, has been validated on the basis of the laboratory experiments.
Chinju, H.*; Nagasaki, Shinya*; Tanaka, Satoru*; Sakamoto, Yoshiaki; Takebe, Shinichi; Ogawa, Hiromichi
Journal of Nuclear Science and Technology, 38(8), p.645 - 654, 2001/08
Times Cited Count：3 Percentile：27.1(Nuclear Science & Technology)no abstracts in English
JNC TN9400 2000-021, 104 Pages, 2000/03
JNC-TN9400-2000-021.pdf:5.21MB
ln this report, research works performed in the Structura1 Safety Engineering Group of OEC/JNC are summarized as the final report of the doctoral fellowship. The main objective of this study is for the enhancement of the nondestructive evaluation techniques for structural components of both magnetic and nonmagnetic material. Studies in three topics have been carried out aiming at the quantitative evaluation of crack with the eddy current testing and the validation of a natural magnetic field based NDE method for detecting mechanical damages in a paramagnetic material. ln the first part of the study, an approach to the reconstruction of the natural crack was proposed and implemented with an idealized crack model for its validation. ln the second part, the correlation of the natural magnetization and the mechanical damages in the SUS304 stainless steel was investigated by using an experimental approach. ln part 3, an inverse method of the measured magnetic fields is proposed for the reconstruction of magnetic charges in the inspected material by using an optimization method and wavalet. As the first work, an approach to the reconstruction of an idealized natural crack of non-vanishing conductivity is proposed with use of signals of eddy current testing. Two numerical models are introduced at first for modeling the natural crack in order to represented it with a set of crack parameters. A method for the rapid prediction of the eddy current testing signals coming from these idealized cracks is given then by extending a knowledge based fast forward solver to the case of a non-vanishing conductivity. Based on this fast forward solver, the inverse algorithm of conjugate gradient method is updated to identify the crack parameters. Several examples are presented finally as a validation of the proposed strategy. The results show that both the two numerical models can give reasonable reconstruction results for signal of low noise. The model concerning the touch of ...
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.
Tanaka, Satoru*
JNC TJ8400 2000-003, 62 Pages, 2000/02
JNC-TJ8400-2000-003.pdf:11.88MB
For the safety assessment of radioactive waste disposal, it is important to elucidate the effect of colloids on radionuclide migration, which are released with dissolution of cementitious materials composing engineered barricr. In the previous work, we identified and characterized the colloidal particles in the solutions contacting cement hydrates, OPC and low-alkaline cement paste, and observed the release of the colloid particle. In the present work, we performed same experiments as the last year to confirm the reproducibility of the colloid release. We studied the leaching behavior of the colloid when OPC and low-alkaline cement past contact water flow. Furthermore, the effect of an alumina particle was studied, which is used as a barrier material for colloid migration. The following conclusions were derived: (1)In the solution contacting cement paste, the small amount of particles, which are considered as CaCO or silicate colloids were observed. Thus, the reproducibility of the last work was confirmed. (2)The leaching of colloid in the solution was confirmed by water flow through the cement paste. The concentration of particle was as low as 10
10
mL
. (3)Al0 powder, with the diameter of 200150m, was found to be effective to some extent as a barrier for a colloid migration from low-alkaline cement paste.
Ueta, Shinzo*; *; *; *
JNC TJ8400 2000-002, 364 Pages, 2000/02
JNC-TJ8400-2000-002.pdf:16.99MB
Japan Nuclear Cycle Development Institute (JNC) have been setting migration parameters and developing its database for the 2nd Progress Report of HLW Geological Disposal (H12 Report). In this study, experimentswere carried out to certify the reliability of parameters and scenario, and examination was carried out to survey procedures of quality management. The main contents are as follows. (1)Data acquisition for certification of migration parameters. The effect of NH complex of Pd on distribution coefficients (Kd) of Pd on both bentonite and rocks, and the effect of sulfate and carbonate complexes of Am on Kds of Am on bentonite are investigated. Kds of Pd depended on NH
concentration in aqueous. The dependence varied with pH. Effects of sulfate and carbonate complexes on Kds of Am were not remarkable. Apparent diffusivities of Cs in bentonite saturated by saline water were measured. It was confirmed that the apparent diffusivities of Cs in saline water were similar to those in pure water. (2)Evaluation of colloidal effect on nuclide migration. An evaluation of validity of analytical model (Hwang's model) for nuclide migration under existence of colloids and investigation of characterization of colloids in groundwater were carried out. As the results, it was indicated that the Hwang's model was appropriate, and it was found that samplingtechnique influenced concentration and size distribution of colloids. (3)Influence of organic substances on solubility. Solubility of Th was measured under the condition with humic acid and carbonate. It increased roughly in proportion to the concentration of humic acid. And it was remarkably high under the condition with carbonate. It was confirmed that Th solubility data set in H12 report was conservative, even though humic acid existed in groundwater. (4)Use of Mechanistic Models for Safety Assessment. The integrated sorption/diffusion model has been used to calculate K
, D
and D
values ...
Chinju, H.*; Nagasaki, Shinya*; Tanaka, Satoru*; Tanaka, Tadao; Ogawa, Hiromichi
Materials Research Society Symposium Proceedings, Vol.556, p.743 - 750, 1999/00
no abstracts in English
Sakamoto, Yoshiaki; ; *; *
Proc. of 7th Int. Conf. on Radioactive Waste Management and Environmental Remediation (ICEM'99)(CD-ROM), 5 Pages, 1999/00
no abstracts in English
Tanaka, Tadao; Muraoka, Susumu
JAERI-Research 98-017, 20 Pages, 1998/03
JAERI-Research-98-017.pdf:0.91MB
no abstracts in English
Tanaka, Tadao; Ogawa, Hiromichi
JAERI-Conf 99-004, p.654 - 661, 1998/03
no abstracts in English
Ueta, Shinzo*
PNC TJ1211 98-002, 46 Pages, 1998/02
None
