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Journal Articles

Chemical misfit origin of solute strengthening in iron alloys

Wakeda, Masato*; Tsuru, Tomohito; Koyama, Masanori*; Ozaki, Taisuke*; Sawada, Hideaki*; Itakura, Mitsuhiro; Ogata, Shigenobu*

Acta Materialia, 131, p.445 - 456, 2017/06

 Times Cited Count:27 Percentile:80.02(Materials Science, Multidisciplinary)

Most of the solute species show a significant interaction with the dislocation core, while only several solute species among them, such as Si, P, and Cu, significantly lower the Peierls potential of the screw dislocation motion. A first-principles interaction energy with the "Easy-core" structure excellently correlates with the change in the $$gamma$$-surface caused by solute atoms (i.e., chemical misfit). We show the availability of the interaction energy to predict the effect of each species on macroscopic critical resolved shear stress (CRSS) of the dilute Fe alloy. The CRSS at low and high temperature for various alloys basically agree with experiment CRSS. These results provide a novel understanding of the interaction between a screw dislocation and solute species from the first-principles.

Journal Articles

Segmentation of granite and single fracture through microfocus X-ray CT and its application

Ishikawa, Tomohiro*; Yasuhara, Hideaki*; Sawada, Atsushi; Kishida, Kiyoshi*

Dai-50-Kai Jiban Kogaku Kenkyu Happyokai Rombunshu, p.515 - 516, 2015/06

no abstracts in English

Journal Articles

Measurements of fracture aperture in granite core using microfocus X-ray CT and fluid flow simulation

Kishida, Kiyoshi*; Ishikawa, Tomohiro*; Higo, Yosuke*; Sawada, Atsushi; Yasuhara, Hideaki*

Proceedings of 49th US Rock Mechanics/Geomechanics Symposium (CD-ROM), 6 Pages, 2015/06

In order to estimate the changes in fracture aperture under various long-term confining and thermal conditions, measurements of the fracture aperture are conducted using microfocus X-ray CT. Through the imaging data, the altitude of the fracture surface and the contact points are evaluated, and contact ratios for the fracture, the JRC and the aperture distribution are estimated. On the other hand, measurements are also conducted using a laser scan profile sensor, and some parameters are estimated. In comparing these parameters, the validity of the X-ray CT data and an analysis of the data will be discussed. In addition, a fracture flow simulation will be conducted using the altitude and aperture data obtained by the microfocus X-ray CT.

JAEA Reports

Enhancement of the methodology of repository design and post-closure performance assessment for preliminary investigation stage, 2; Progress report on NUMO-JAEA collaborative research in FY2012 (Joint research)

Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Hayano, Akira; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.

JAEA-Research 2013-037, 455 Pages, 2013/12

JAEA-Research-2013-037.pdf:42.0MB

Following FY2011, JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, the tree diagram of methodology of groundwater travel time has been extended for crystalline rock, in addition, tree diagram for sedimentary rock newly has been organized. With regard to (2) study on scenario development, the existing approach has been improved in terms of a practical task, and applied and tested for near field focusing on the buffer. In addition, the uncertainty of some important processes and its impact on safety functions are discussed though analysis. With regard to (3) study on setting radionuclide migration parameters, the approaches for parameter setting have been developed for sorption for rocks and solubility, and applied and tested through parameter setting exercises for key radionuclides.

Journal Articles

Estimation of fracture flow in considering the inhomogeneous structure of single rock fractures

Kishida, Kiyoshi*; Sawada, Atsushi; Yasuhara, Hideaki*; Hosoda, Takashi*

Soils and Foundations, 53(1), p.105 - 116, 2013/02

 Times Cited Count:21 Percentile:62.5(Engineering, Geological)

Considering the safe, long-term sequestration of energy byproducts, such as radioactive waste, one of the important parameters is the groundwater flow velocity through the void of rock masses and/or fractures. In this research work, two-dimensional seepage flow analyses, using the authors' proposed 2D model, with considering the inertia term, are carried out for single fracture permeability tests under conditions which allow for the application of the cubic law. In comparing the results of the experiments with the numerical simulations, the results of the simulation show a good agreement with the experimental results. From these simulation results, the fracture flow of an inhomogeneous structure is discussed, along with the local Reynolds number, and the resistance through the fracture geometry is considered. Consequently, under the condition of a mean Reynolds number of less than 1.0, the inertia terms cannot affect on the fracture flow, but the hydraulic resistance can affect.

JAEA Reports

Enhancement of the methodology of repository design and post-closure performance assessment for preliminary investigation stage; Progress report on NUMO-JAEA collaborative research in FY2011 (Joint research)

Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Hayano, Akira; Mitsui, Seiichiro; Taniguchi, Naoki; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.

JAEA-Research 2012-032, 298 Pages, 2012/09

JAEA-Research-2012-032.pdf:33.68MB

JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation phase. The topics and the conducted research are follows; (1) Study on selection of host rock: in terms of hydraulic properties, items for assessing rock property, and assessment methodology of groundwater travel time has been organized with interaction from site investigation. (2) Study on development of scenario: the existing approach has been embodied, in addition, the phenomenological understanding regarding dissolution of and nuclide release from vitrified waste, corrosion of the overpack, long-term performance of the buffer are summarized. (3) Study on setting nuclide migration parameters: the approach for parameter setting has been improved for sorption and diffusion coefficient of buffer/rock, and applied and tested for parameter setting of key radionuclides. (4) Study on ensuring quality of knowledge: framework for ensuring quality of knowledge has been studied and examined aimed at the likely disposal facility condition.

Journal Articles

Dependence of fracture geometry and spatial variation in pressure on hydraulic conductivity in rock fractures

Kishida, Kiyoshi*; Hosoda, Takashi*; Sawada, Atsushi; Sato, Hisashi; Nakashima, Shinichiro*; Yasuhara, Hideaki*

Harmonising Rock Engineering and the Environment, p.1327 - 1330, 2011/10

Although it is generally known that a natural rock fracture indicates a complex aperture distribution, the fracture is an ideal representation of the parallel plate model. The cubic law is applied to evaluate the hydraulic properties of fractured rock. From several previous research works, it is known that the cubic law can be applied when the Reynolds number is less than 1.0 and that the advection term can basically be ignored in such fracture flows. In this research work, two-dimensional seepage flow analyses, using the authors' proposed 2D model which is considered with the advection term, are carried out for single fracture hydro-conductivity experiments under conditions which allow for the application of the cubic law. From the numerical results, the validity of the 2D model is discussed along with the local Reynolds number and the application of the cubic law.

JAEA Reports

Geometrical properties of tension-induced fractures in granite

Sato, Hisashi; Yasuhara, Hideaki*; Sawada, Atsushi

JAEA-Research 2010-069, 45 Pages, 2011/03

JAEA-Research-2010-069.pdf:13.04MB

Considering a safe, long-term sequestration of energy byproducts such as high level radioactive wastes, it is of significant importance to well-constrain the hydraulic and transport behavior of targeted permeants within fractured rocks. Specifically, fluid flow within low-permeability crystalline rock masses (e.g., granite) is often dominated by transport in through-cutting fractures, and thus careful considerations are needed on the behavior. There are three planes along that granites fail most easily under tension, and those may be identified as the rift, grain, and hardway planes. In this research, geometrical properties of tension-induced fractures were evaluated. Results show that rift planes are less rougher than the other planes of grain and hardway, and grain planes are generically rougher than the other planes of rift and hardway.

Journal Articles

Development of next-generation technology for integrated site characterization of deep geological repositories

Osawa, Hideaki; Umeki, Hiroyuki; Ota, Kunio; Hama, Katsuhiro; Sawada, Atsushi; Takeuchi, Shinji; Semba, Takeshi; Takase, Hiroyasu*; McKinley, I. G.*

Proceedings of International Waste Management Symposium 2009 (WM '09) (CD-ROM), 11 Pages, 2009/03

The focus of this paper is development of advanced technology from the field of Knowledge engineering, termed the Information Synthesis and Interpretation System (ISIS), which incorporates past experience and know-how currently being obtained in complex URL projects within Expert System (ES) modules in 2009.

JAEA Reports

Establishment of advanced integration technology for site characterization of deep geological repository; Development of information synthesis and interpretation system; Annual report 2007 (Contract research)

Osawa, Hideaki; Ota, Kunio; Hama, Katsuhiro; Sawada, Atsushi; Takeuchi, Shinji; Amano, Kenji; Saegusa, Hiromitsu; Matsuoka, Toshiyuki; Miyamoto, Tetsuo; Toyoda, Gakuji; et al.

JAEA-Research 2008-085, 742 Pages, 2008/11

JAEA-Research-2008-085-1.pdf:26.22MB
JAEA-Research-2008-085-2.pdf:16.64MB
JAEA-Research-2008-085-3.pdf:28.27MB

This report shows the results the project for the establishment of comprehensive site characterization technology, entrusted from Natural Resources and Energy Agency, Ministry of Economy, Trade and Industry Natural Resources and Energy Agency in 2007.

JAEA Reports

Development and management of the knowledge base for the geological disposal technology; Annual report 2006

Umeda, Koji; Oi, Takao; Osawa, Hideaki; Oyama, Takuya; Oda, Chie; Kamei, Gento; Kuji, Masayoshi*; Kurosawa, Hideki; Kobayashi, Yasushi; Sasaki, Yasuo; et al.

JAEA-Review 2007-050, 82 Pages, 2007/12

JAEA-Review-2007-050.pdf:28.56MB

This report shows the annual report which shows the summarized results and topic outline of each project on geological disposal technology in the fiscal year of 2006.

Oral presentation

Development of Information Synthesis and Interpretation System (ISIS), 8; Basic design of ISIS

Osawa, Hideaki; Sawada, Atsushi; Umeki, Hiroyuki; Hama, Katsuhiro; Takase, Hiroyasu*; Tachibana, Shoko*

no journal, , 

This presentation shows basic design of Information Synthesis and Interpretation System based on the traial of making some expert systems.

Oral presentation

Development of Information Synthesis and Interpretation System (ISIS), 1; Fundamental concept for development of ISIS

Umeki, Hiroyuki; Osawa, Hideaki; Ota, Kunio; Hama, Katsuhiro; Sawada, Atsushi; Takase, Hiroyasu*

no journal, , 

This presentation shows the fundamental concept for the development of Information Synthesis and Interpretation System(ISIS).

Oral presentation

Development of Information Synthesis and Interpretation System (ISIS), 1; Approach and future plan

Semba, Takeshi; Osawa, Hideaki; Ota, Kunio; Hama, Katsuhiro; Sawada, Atsushi; Umeki, Hiroyuki

no journal, , 

no abstracts in English

Oral presentation

Information Synthesis and Interpretation System (ISIS), 1; An Overview

Semba, Takeshi; Osawa, Hideaki; Hama, Katsuhiro; Takeuchi, Shinji; Iwatsuki, Teruki; Sawada, Atsushi; Umeki, Hiroyuki

no journal, , 

Japan Atomic Energy Agency has now been developed Information Synthesis and Interpretation System (ISIS) which supports flexible planning of site characterization taking into account of changes in scientific understandings and socio-political conditions. This paper describes the progress of development of ISIS.

Oral presentation

Current status of development of next-generation Information Synthesis and Interpretation System (ISIS), 1; An Overview of ISIS

Semba, Takeshi; Osawa, Hideaki; Iwatsuki, Teruki; Hama, Katsuhiro; Takeuchi, Shinji; Sawada, Atsushi; Umeki, Hiroyuki

no journal, , 

As site investigation proceeds and information obtained on geological environments increases, the characterization plan has to be iteratively reviewed and modified to reflect improved understanding. Thus JAEA teams are developing a system for transferring the know-how and decision-making process, based on the experiences from JAEA's URL program, which are needed for the future site investigations.

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