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Journal Articles

The Effect of montmorillonite partial density on the role of colloid filtration by a bentonite buffer

Kurosawa, Susumi; Tanaka, Satoru*; James, S. C.*; Yui, Mikazu

Journal of Nuclear Science and Technology, 43(5), p.605 - 609, 2006/05

 Times Cited Count:8 Percentile:52.29(Nuclear Science & Technology)

In this work, the effective clay density as a function of interstitial pore size was estimated by applying the homogenization analysis (HA) of bentonite. In the estimation by the HA method, the interstitial pore size was set up to be $$<$$ 1 nm which is the smallest size equivalent to colloid. The results indicate that the interstitial pore is estimated to be 1 nm or less if the effective clay density in the buffer is higher than 1.5 Mg/m$$^{3}$$ and it is also suggested that the penetration of colloidal fine particles in the buffer did not occur.

JAEA Reports

A Study on Effects of Colloids on Radionuclide Migration in High-Level Radioactive Waste Geological Disposal System -The Examinations after Publication of the H12 Report-

Kurosawa, Susumi

JNC TN8400 2005-007, 36 Pages, 2005/03

JNC-TN8400-2005-007.pdf:1.73MB

This paper presents the examinations that were performed after publication of the H12 report to evaluate the effects of colloids in the engineered barrier, the natural barrier and these boundaries on the performance assessment of radioactive waste geological disposal system. This paper presents the interesting topics that is summarized as a dissertation based on results (contributed papers) obtained in Japan Nuclear Cycle Development Institute by studying under with Prof. Satoru Tanaka, Department of Quantum Engineering and Systems Science, The School of Engineering, The University of Tokyo.

Journal Articles

Effects of Colloids and Microorganisms on Radionuclide Migration in Fractured Rock

Kurosawa, Susumi; Yui, Mikazu; Yoshikawa, Hideki

International Symposium NUCEF2005, 0 Pages, 2005/02

It is reported that the nuclide migration in groundwater is enhanced according to transport behavior of colloids compared with the migration behavior as the ion when the nuclide generates colloids. For example, in the colloids and radionuclide retardation experiment (CRR experiment) in the Grimusel test site in Switzerland had been performed as collaboration of JNC and NAGRA (Switzerland), the possibility that the nuclide migration was enhanced by the influence of the colloids in the groundwater was indicated. We will present on the simulations of the analysis by numerical code COLFRAC which describes colloid-facilitated solute transport in fractured media. Moreover, in order to evaluate the impact of microorganism on the performance assessment for geological disposal of HLW, we simulated effects of microorganism on radionuclide migration by using the COLFRAC code.

Journal Articles

Effects of Colloids and Microorganisms on Radionuclide Migration in Fractured Rock

Kurosawa, Susumi; Yui, Mikazu; Yoshikawa, Hideki

International Symposium NUCEF2005, 0 Pages, 2005/02

On the geological disposal of high-level radioactive waste (HLW), it is known that the actinide ion which is released from the HLW generates true-colloids with hydrolysis reaction, and forms pseudo- colloids by sorption reaction onto the colloids in the groundwater. Recently, it is reported that the radionuclide migration in groundwater is enhanced by transport behavior of colloids compared with the migration behavior of the solute. For example, the in-situ experiment on the colloids and radionuclide retardation (CRR experiment) in the Grimsel test site in Switzerland had been performed by the collaboration among NAGRA (Switzerland), ENRESA (Spain), ANDRA (France), FZK-INE (Germany), USDoE/SNL (U.S.A) and JNC (Japan), the possibility of the radionuclide migration enhancement by the influence of the colloids was indicated. We will present the modeling results by numerical code COLFRAC which describes colloid-facilitated solute transport in fractured media. Moreover, in order to evaluate the impact of microorganisms on the performance assessment for geological disposal of HLW, we simulated effects of microorganism as a colloid on radionuclide migration by using the COLFRAC code.

Journal Articles

Influence of the Colloids on Performance Assessment for Radioactive Waste Geological Disposal System; Based on the Results of Laboratory, in-Situ Programs and Analysis

Yui, Mikazu; Kurosawa, Susumi; Iijima, Kazuki

Genshiryoku Bakkuendo Kenkyu, 11(1), p.45 - 51, 2005/00

The information of experimental and theoretical studies which were performed with Japan Nuclear Cycle Development Institute (JNC) as leader to evaluate the influence of colloid, organic material and microorganism in artificial barrier, natural barrier and its boundary area on performance assessment of radioactive waste geological disposal system were presented. Furthermore, the experimental and analytical results of laboratory and in-situ programs which were performed on and after compilation of the results of R&D studies relevant to radioactive waste management by JNC to develop and advance the transport model of radionuclide with colloid, organic material and microorganism were indicated.

JAEA Reports

Model Analysis on the Colloid and Radionuclide Retardation Experiment at the Grimsel Test Site

Kurosawa, Susumi; Ibaraki, Motomu*; Scott, J.*; Yui, Mikazu; Russell, A.*

JNC TN8400 2004-016, 35 Pages, 2004/09

JNC-TN8400-2004-016.pdf:1.18MB

To evaluate the influence of colloids on radionuclide transport through the fractured rock, the colloid and radionuclide retardation experiment project were carried out in a shear zone in the Grimsel Test Site on one of JNC-NAGRA internatinal collaboration programs. In this study, the results of the transport experiments were analyzed by numerical simulation code of radionuclide transport, COLFRAC, which describe colloid-facilitated solute transport in fractured media.

Journal Articles

Effects of Kinetic Radionuclide Sorption onto Colloids for Radionuclide Transport in Fractured Rock; Experimental and Numerical Studies

Kurosawa, Susumi; Ibaraki, Motomu*; Yui, Mikazu; Ueda, Shinzo*; Yoshikawa, Hideki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(3), p.249 - 256, 2004/09

Colloidal effect is one of the major factors to enhance the transport of radionuclide in groundwater. In this study, the impact of kinetic reactions of radionuclide sorption onto both the fracture wall and colloid on the transport behavior of radionuclide were investigated by carrying out the transport experiment of the radionuclide with colloid through fractured rock. In the experiments, the Cs and clay colloid were used as moderately sorbing radionuclide and typical natural colloid by the concentration of 1.0$$times$$10$$^{-6}$$ g/l (7.5$$times$$10$$^{-9}$$ mol/l) and 3.5$$times$$10$$^{-3}$$ g/l, respectively. The granodiorite with artificially the single fracture (dimension: 50$$times$$50$$times$$0.5 mm) was used. The results of the transport experiments were analyzed by numerical simulation code of radionuclide transport COLFRAC which can model radionuclide transport based on either equilibrium or kinetic reaction of radionuclide sorption onto fracture wall and colloid. Consequently, it was indicated that calculated results strongly dep

JAEA Reports

Evaluation in an Effect of Microorganism on Performance Assessment by COLFRAC

Kurosawa, Susumi; Sasaki, Ryoichi; Ueda, Shinzo*; Yoshikawa, Hideki

JNC TN8400 2004-012, 68 Pages, 2004/07

JNC-TN8400-2004-012.pdf:5.37MB

In order to evaluate the impact of microorganism by COLFRAC, which simulates colloid-facilitated contaminant migration, the microorganism - radionuclide sorption data and microbial films data in deep geological environment were surveyed. After the survey, the data conversion to be able to calculate the effect of them on performance assessment in COLFRAC has been undertaken. As the results of calculation by COLFRAC, the transport behavior of radionuclide may be enhanced, when radionuclide will be taken in the microorganism. Furthermore, the results indicated that the transport rate of radionuclide depends on microbial concentration.

Journal Articles

Experimental and Numerical Studies on Colloid-enhanced Radionuclide Transport: The Effects of Kinetic Radionuclide Sorption onto Colloidal Particles

Kurosawa, Susumi; Yui, Mikazu; Yoshikawa, Hideki; Ibaraki, Motomu*; Ueda, Shinzo*

Abstracts P.510-511, p.510 - 511, 2004/00

Many studies have shown that colloidal particles which exist in ground water can facilitate radionuclide transport in subsurface environments. We conducted a series of laboratory experiments to investigate the effects of radionuclide sorption onto colloids and the surfaces of rock fractures. We focused on overall effects related to the kinetic behavior of those sorption processes. A mixed solution of cesium and clay colloids was injected into an artificially-created single fracture in a granite column. The fracture aperture and length are 0.5 mm and 50 cm, respectively. Numerical simulations were conducted to analyze the experiment results using a numerical code COLFRAC which can simulate colloid-facilitated solute transport in discretely-fractured porous media. The numerical formulation allows for either equilibrium or kinetic sorption onto the fracture walls, and the mobile and filtered colloidal particles. A series of experimental and numerical analyses shows that migration of cesium is facilitated by mobile colloidal particles which can sorb cesium and migrate in the fracture. The analyses also demonstrate that cesium migration is significantly enhanced if desorption of cesium from the colloids is a slow kinetic process and illustrate the importance of evaluating the parameters which describe such kinetic processes. Furthermore, radionuclide transport is likely to be retarded if mobile colloidal particles which sorb radionuclides are vigorously filtered on the fracture surfaces.

Journal Articles

Experimental and Numerical Studies on Colloid-Enhanced Radionuclide Transport; The Effect of Kinetic Radionuclide Sorption onto Colloidal Particles

Kurosawa, Susumi; Ibaraki, Motomu*; Yui, Mikazu; Ueda, Shinzo*; Yoshikawa, Hideki

Materials Research Society Symposium Proceedings, Vol.824, 473 Pages, 2004/00

We conducted a series of laboratory experiments to investigate the effects of radionuclide sorption onto colloids and the surfaces of rock fractures. We focused on overall effects related to the kinetic behavior of those sorption processes. A mixed solution of cesium and clay colloids was injected into an artificially-created single fracture in a granite column. Numerical simulations were conducted to analyze the experiment results using a numerical code COLFRAC which can simulate colloid-facilitated solute transport in discretely-fractured porous media. A series of experimental and numerical analyses show that migration of cesium is facilitated by mobile colloidal particles which can sorb cesium and migrate in the fracture. The analyses also demonstrate that cesium migration is significantly enhanced if desorption of cesium from the colloids is a slow kinetic process and illustrate the importance of evaluating the parameters which describe such kinetic processes. Furthermore, radionuclide transport is likely to be retarded if mobile colloidal particles which sorb radionuclides are vigorously filtered on the fracture surfaces.

Journal Articles

Practical Availability of Radionuclide Transport Model based on the Interaction among Radionuclide, Colloid and Rock

Kurosawa, Susumi; Ueda, Shinzo*; Yui, Mikazu; Kato, Hiroyasu*; Hayashi, Kenichi*; *; Yoshikawa, Hideki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 2(4), p.460 - 468, 2003/12

None

JAEA Reports

Transport Behavior of Colloids through Compacted Bentonite -Study with 3wt%Nacl Solution and Ca-Type Bentonite-

Kurosawa, Susumi; Kuno, Yoshio*; Morooka, Koichi; Ueda, Shinzo*

JNC TN8430 2003-006, 39 Pages, 2003/03

JNC-TN8430-2003-006.pdf:26.18MB

The transport behavior of colloids through the compacted sand-bentonite mixture was investigated by the column experiments. Colloidal gold was used to simulate the mobile colloids because gold colloid was stabilized easily. The sand-bentonite mixtures were prepared by mixing 30wt.% silica sand with the bentonite (Na-type and Ca-type) and were compacted at the dry density of 1.6g/cm$$^{3}$$. The colloidal particles in the 3.5% NaCl solution migrated through the compacted sand- Na bentonite mixture at 8kgf/cm$$^{2}$$ of injection pressure. However colloidal migration was not observed after injection pressure of the colloidal solution was lowered below the swelling pressure. And the selective flow path of colloids in the compacted sand-bentonite mixture was observed after the experiment. On the other hand, colloids in the pure water were filtered by the compacted sand- Ca bentonite mixture.

JAEA Reports

Effect of colloids on radionuclide migration assessment for radioactive waste geological disposal

Kurosawa, Susumi; Yoshikawa, Hideki; Yui, Mikazu

JNC TN8410 2002-010, 40 Pages, 2002/11

JNC-TN8410-2002-010.pdf:0.65MB

It is necessary to evaluate the effect of colloids on radionuclide transport in geologic environments relevant to safety assessment of radioactive waste geological disposal. This report summarizes the recent researches from the viewpoint of colloids generation in radioactive waste disposal system, e汀ffect of the colloids on the radionuclide transport, and transport model development. (1)The colloid of radionuclide could be generated by the waste dissolution. It is possible to be filtered by the engineered barrier system. (2)The effect of humic substance and biological colloids on radionuclide migration should be estimated, thus the researches on the interaction of organic matter, microbe and radionuclide are required. (3)Colloid generation from bentonite and cement material has been investigated, however the data in due consideration of the alteration are not sufficient, especially for discussion on the effect of these colloids on radionuclide transport. (4)To simulate the radionuclide migration behavior under existence of colloids, the modeling of the interaction among three phases (radionuclide-colloid-rock) is important.

Journal Articles

Alteration of bentonite in highly alkaline conditions and its effect on colloid filtration

Kurosawa, Susumi; Shibata, Masahiro; Ueda, Shinzo*; Ichige, Satoru*; Hayashi, Kenichi*; Yui, Mikazu

Nihon Genshiryoku Gakkai Wabun Rombunshi, 1(2), p.244 - 248, 2002/00

None

Journal Articles

None

Yoshikawa, Hideki; Kurosawa, Susumi

Donen Giho, (99), p.65 - 72, 1996/09

None

15 (Records 1-15 displayed on this page)
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