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Tochigi, Yoshikatsu; Tachi, Yukio
JAEA-Data/Code 2009-029, 39 Pages, 2010/03
JAEA-Data-Code-2009-029.pdf:3.33MB
Japan Atomic Energy Agency (JAEA) has been developing database of diffusion parameters in buffer material (bentonite) and rock, which are key parameters for safety assessment of the geological disposal. JAEA is continuing development and updating such as parameter estimation, finding data trend, examining related information concerning reliability have been carried on to apply the database in parameter setting for safety assessment. As the result of data addition, total data count of effective diffusion coefficient is 2,020 (599 for measured value) and that of apparent diffusion coefficient is 1,747 (measured value). As an example of practical use of the improved database, the example of evaluation for the plot of a diffusion coefficient vs. dry and partial smectite density was discussed. As a result of introducing partial smectite density for database update, domestic and foreign bentonites are normalized on same index and compared each other on the same plot of measured data.
Tochigi, Yoshikatsu; Tachi, Yukio
JAEA-Data/Code 2008-035, 57 Pages, 2009/02
JAEA-Data-Code-2008-035.pdf:3.0MB
The database for utilizing the data related to the diffusion coefficient of nuclides in the buffer material and rock was improved on the basis of the existing diffusion database. Renewals of database definition include maintenance of database contents, extension of stored data scope, etc. The database was updated with especially emphasis on introduction of estimated value in data evaluation and description concerning reliability of information. Existing data of domestic rock were updated by implementation of the result of literature survey in accordance with the definition of updated database and new data of domestic bentonite. As the result of data addition, total data count of effective diffusion coefficient is about 450 and that of apparent diffusion coefficient is about 1,350. As an example of practical use of the improved database, the example of evaluation for the plot of a diffusion coefficient of dry density or porosity was discussed.
Tachi, Yukio; Tochigi, Yoshikatsu; Suyama, Tadahiro; Saito, Yoshihiko; Ochs, M.*; Yui, Mikazu
JAEA-Data/Code 2008-034, 36 Pages, 2009/02
JAEA-Data-Code-2008-034.pdf:5.72MB
Japan Atomic Energy Agency (JAEA) has been developing databases of sorption and diffusion parameters in buffer material and rock, which are key parameters for safety assessment of the geological disposal. The new web-based sorption and diffusion database system (JAEA-SDB/DDB) has been developed to utilize quality assuring procedure and to allow effective application for parameter setting, based on the existing database. In the present report, practical examples were illustrated regarding the applicability of the database system to the parameter setting by using additional functions such as QA information and parameter estimation. This database system is expected to make it possible to obtain quick overview of the available data from the database, and to have suitable access to the respective data for parameter-setting for performance assessment and parameter-deriving for mechanistic modeling in traceable and transparence manner.
Tochigi, Yoshikatsu; Yoshikawa, Hideki; Aoki, Kazuhiro; Yui, Mikazu; Asano, Takahiro*; Honjo, Hideko*; Haginuma, Masashi*; Kawakami, Yasushi*; Suzuki, Kazunori*
JAEA-Research 2008-025, 55 Pages, 2008/03
JAEA-Research-2008-025.pdf:8.55MB
Results of joint research on fiscal year 2006 between Japan Atomic Energy Agency (JAEA) and Institute of Research and Innovative (IRI) titled as "Study on investigation of microbial effects for geological disposal" are described in this report. The objective of this study is to develop a method for estimating microbial effects for barrier performance of geological disposal site. The modeling was performed to examine the effect on the change in groundwater chemistry (mainly by electron acceptors) by microbial metabolism as well as microbial activities. In order to use the data (chemical composition, biomass, etc.) in the MINT code, groundwater was collected from the drilled well prepared for chemical and microbial analyses of groundwater. The well was prepared in observation field near Horonobe Underground Research Center of JAEA in fiscal year 2006. Then, numerical modeling using collected data of groundwater with numerical modeling program code "MINT" considering microbial effects was carried out. The modeling was carried out to evaluate the microbial effect for stability of chemical and microbial composition of groundwater. As the result of the modeling, relatively low microbial effect for groundwater composition was observed in particular for the concentration of dissolved methane, methanogen, sulfur reducing bacteria (SRB) and sulfur ion. The result shows that low redox potential is stable in the well in spite of shallow depth.
Tochigi, Yoshikatsu; Kogawa, Noritaka*; Mukai, Satoru*; Jintoku, Takashi*; Sasamoto, Hiroshi; Shibata, Masahiro; Yui, Mikazu
JAEA-Research 2007-024, 27 Pages, 2007/03
JAEA-Research-2007-024.pdf:1.83MB
In the safety assessment of high-level radioactive waste (HLW) geological disposal, it is important to understand diffusion behavior of radionuclides for evaluation of retardation capacity in the host rock. In this study, non steady state diffusion experiments with non-sorbing ion ware carried out using several granitic rock samples of different length and the matrix diffusion depth was evaluated. As the results of experiment, it is confirmed that the non-sorbing ion can diffuse into the unaltered zone of granitic rock at least about 200 mm in depth and almost same diffusion coefficient is estimated for all rock samples independent of length. Based on these results, it is expected that matrix diffusion of nuclides is acting on a scale of several dozens of centimeters in the granitic rock.
Tochigi, Yoshikatsu; Yoshikawa, Hideki; Aoki, Kazuhiro; Yui, Mikazu; Honjo, Hideko*; Haginuma, Masashi*; Kawakami, Yasushi*; Suzuki, Kazunori*
JAEA-Research 2007-010, 51 Pages, 2007/03
JAEA-Research-2007-010.pdf:4.82MB
Results of joint research on Fiscal 2005 between Japan Atomic Energy Agency (JAEA) and Institute of Research and Innovative (IRI) titled as "Study for investigation of microbial effects on geological disposal" are described in this report. The objective of this study is constructing advanced method for examining microbial effect for barrier performance of geological disposal site. In fiscal 2005, groundwater and rock core sample have been collected from drilled well on observation field near Horonobe Underground Research Center of JAEA and chemical analysis for collected ground water have been carried out and sensitivity analysis for existing observed data of groundwater with numerical analysis program code "MINT" considering microbial effect have been carried out.
Tochigi, Yoshikatsu; Shibata, Masahiro; Sato, Haruo; Kitamura, Akira
JAEA-Data/Code 2007-010, 14 Pages, 2007/03
JAEA-Data-Code-2007-010.pdf:3.32MB
The Diffusivity Database (DDB) System developed on early 2006 was upgraded to apply the data of effective diffusion coefficient of the nuclides in the rock matrix for the "H12: Project to Establish the Scientific and Technical Basis for HLW Disposal in Japan", and the data in the buffer materials from literature survey was newly added. Some functions of data search and selection were reformed to improve the level of convenience. This DDB system (work on MS-AccessTM) is released to the public through Web server managed by JAEA.
Tochigi, Yoshikatsu; Sasamoto, Hiroshi; Shibata, Masahiro; Sato, Haruo; Yui, Mikazu
JAEA-Data/Code 2006-008, 16 Pages, 2006/03
JAEA-Data-Code-2006-008.pdf:1.15MB
The development of the database system has been started to manage with the generally used. The database system has been constructed based on datasheets of the effective diffusion coefficient of the nuclides in the rock matrix in order to be applied on the "H12: Project to Establish the Scientific and Technical Basis for HLW Disposal in Japan". In this document, the examination and expansion of the datasheet structure and the process of construction of the database system and conversion of all data existing on datasheets are described. As the first step of the development of the database, this database system and its data will continue to be updated and the interface will be revised to improve the availability. The developed database system is attached on the CD-ROM as the file format of Microsoft Access.
Tochigi, Yoshikatsu*; Kanno, Takeshi*; Ueno, Shunichiro*; Kubota, Nobuhiko*; Nishino, Junnya*; Fukunaga, Sakae*
JNC TJ7400 2005-017, 49 Pages, 2004/03
JNC-TJ7400-2005-017.PDF:12.08MB
The analytical procedure is investigated and examined with the aim of considering complex stability constant concerned with abundance ratio of metal ion / organic complexes dissolved in groundwater. The condenser of organic material in groundwater and experimental system for simulating subsurface environment are constructed and the experiment.
Tochigi, Yoshikatsu
no journal, ,
no abstracts in English
Tochigi, Yoshikatsu; Yoshikawa, Hideki; Yui, Mikazu
no journal, ,
no abstracts in English
Miyasaka, Iku*; Fukunaga, Sakae*; Kanno, Takeshi*; Tochigi, Yoshikatsu; Namba, Kenji*
no journal, ,
no abstracts in English
Tachi, Yukio; Saito, Yoshihiko; Tochigi, Yoshikatsu; Ochs, M.*; Kitamura, Akira; Yui, Mikazu
no journal, ,
The sorption and diffusion database has been developed for the safety assessment of geological disposal system. This report has focused on evaluating of quality level and testing the usefulness of the database for possible applications to Kd setting.
Tochigi, Yoshikatsu; Tachi, Yukio; Yui, Mikazu
no journal, ,
no abstracts in English
Tochigi, Yoshikatsu; Tachi, Yukio
no journal, ,
no abstracts in English
Yamazaki, Kazutoshi*; Takao, Hajime*; Kikuchi, Takahiro*; Kuriki, Yoshiro*; Kobayashi, Masato*; Kawakubo, Masahiro*; Shirase, Mitsuyasu*; Iwata, Yumiko*; Tochigi, Yoshikatsu*; Nakayama, Gen*; et al.
no journal, ,
Among factors affecting the corrosion behavior of carbon steel overpack, in order to consider materials (size) and realistic environmental factors which are difficult to reproduce in the laboratory scale test, engineering scale tests in the underground environment were carried out. A mock-up test of the same scale was also carried out on the ground with the aim of controlling and evaluating factors that govern the corrosion phenomenon. As a result of the test for about 3 years, there was no big difference between the average corrosion amount and the maximum corrosion amount of the simulated overpack base metal and the welded part. On the other hand, unlike the laboratory scale test, localization of corrosion due to the adhesion between the buffer material and the simulated overpack was also confirmed during the initial transient period.