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Journal Articles

Discrete fracture network modeling based on in-situ data at underground gallery, 1

Ishibashi, Masayuki; Onoe, Hironori; Sawada, Atsushi; Atsumi, Hiroyuki*; Masumoto, Kazuhiko*; Hosoya, Shinichi*

Dai-42-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.101 - 106, 2014/01

Japan Atomic Energy Agency is proceeding with the Mizunami Underground Research Laboratory Project in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock for geological disposal of high level radioactive wastes. We have carried out discrete fracture network modeling, groundwater flow and particle tracking simulation in order to understand the important factors for the solute transport characterizations. In this paper, a method of discrete fracture network modeling based on in-situ data at underground gallery and the influences of different data interpretation are described.

Journal Articles

Gas entrainment allowance level at free surface and gas dynamics behavior of sodium-cooled fast reactor

Yamaguchi, Akira*; Tatsumi, Eisaku*; Takata, Takashi*; Ito, Kei; Ohshima, Hiroyuki; Kamide, Hideki; Sakakibara, Jun*

Nuclear Engineering and Design, 241(5), p.1627 - 1635, 2011/05

 Times Cited Count:4 Percentile:36.36(Nuclear Science & Technology)

In a sodium-cooled fast reactor, inert gases exist in the primary coolant system either in a state of dissolved gas or free gas bubbles. In the present study, a gas entrainment allowance level at the free surface is discussed and rationalized. The influence of the gas entrainment is evaluated using the void fraction at the core inlet. For the purpose, a plant dynamics code VIBUL has been developed to evaluate the concentration distribution of the dissolved gas and the free gas bubble. It is noted that the background level is already very low in comparison with the induced void reactivity by the void passing the reactor core.

Journal Articles

Rationalization of gas entrainment allowance level at free surface of sodium-cooled fast reactor

Yamaguchi, Akira*; Takata, Takashi*; Tatsumi, Eisaku*; Ito, Kei; Ohshima, Hiroyuki; Kamide, Hideki; Sakakibara, Jun*

Proceedings of 7th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-7) (CD-ROM), 16 Pages, 2008/10

In a sodium-cooled fast reactor, inert gases exist in the primary coolant system either in a state of dissolved gas or free gas bubbles. The gas in the primary system may cause disturbance in reactivity, nucleation site for boiling, etc. Therefore, the allowance level is necessary regarding the gas entrainment and the gas bubble concentration. In the present study, a gas entrainment allowance level is discussed and rationalized. For the purpose, a plant dynamics code VIBUL has been developed to evaluate the concentration distribution of the dissolved gas and the free gas bubble. Assuming that the total void fraction should be kept below 105% of the background level, a preliminary design allowance level of gas entrainment is proposed as the map in terms of the entrainment ratio and the entrained bubble radius. Furthermore, the possibility of bubble removal is investigated to satisfy the allowance level.

JAEA Reports

Assessment of uncertainties associated with characterization of geological environment in the Tono area -Japanese fiscal year, 2006- (Contract research)

Toida, Masaru*; Suyama, Yasuhiro*; Seno, Shoji*; Atsumi, Hiroyuki*; Ogata, Nobuhisa

JAEA-Research 2008-035, 89 Pages, 2008/03

JAEA-Research-2008-035.pdf:5.66MB

"Geoscientific research" performed at the Tono Geoscience Center is developing site investigation, characterization and assessment techniques for understanding of geological environment. Their important themes are to establish a methodology for analyzing uncertainties in heterogeneous geological environment, and to develop investigation techniques for reducing the uncertainties efficiently. This study proposes a new approach where all the possible options in the models and data-sets that cannot be excluded in the light of the evidence available, are identified. This approach enables uncertainties associated with the understanding at a given stage of the site characterization to be made explicitly using an uncertainty analysis technique based on Fuzzy geostatistics. This, in turn, supports the design of the following investigation stage to reduce the uncertainties efficiently. In the study, current knowledge had been compiled, and the technique had been advanced through geological modeling and groundwater analyses in the Tono area. This report systematized the uncertainty analysis methodology associated with the characterization of the geological environment, and organized the procedure of the methodology with the application examples in the study. This report also dealt with investigation techniques for reducing the uncertainties efficiently, and underground facility design options for handling geological uncertainties based on the characterization of the geological environment.

JAEA Reports

Assessment of uncertainties associated with the characterization of the geological environment in the Tono Area -Japanese fiscal year, 2005- (Contract research)

Toida, Masaru*; Suyama, Yasuhiro*; Mori, Takayuki*; Inaba, Takeshi*; Atsumi, Hiroyuki*; Tanaka, Toshiyuki*; Kobayashi, Ichizo*; Nakajima, Makoto*; Ogata, Nobuhisa

JAEA-Research 2007-071, 159 Pages, 2007/09

JAEA-Research-2007-071.pdf:48.05MB

"Geoscientific research" at the Tono Area is developing site investigation, characterization and assessment techniques for understanding of geological environment. Their important goal is to establish a methodology for analyzing uncertainties in a heterogeneous geological environment and to develop investigation techniques for efficiently reducing the uncertainties. In Fiscal Year 17, in addition to information from the MIZ-1 borehole investigation, present knowledge has been compiled. The proposed technique has been improved through conceptual geological modeling and groundwater analyses at the Tono Area. Design options for handling geological uncertainties based on the characterization of the geological environment have also been tested. The results of this study can be summarized as follows: (1) It was shown that the fracture group with NW strike has high correlation with maximum measured transmissivity. This was maybe caused by the effect of regional in situ stress. (2) Through conceptual geological modelling and groundwater analysis, a procedure for modelling of the geological environment with heterogeneous characteristics was proposed. (3) From the viewpoint of improving the design of an underground facility, the existence of uncertainties of the geological environment with heterogeneous characteristics requests multiple options. A design option should be adapted to the geological environment with heterogeneous characteristics.

JAEA Reports

Assessment of heterogeneous geological environment at Tono -Japanese fiscal year 2004- (Contract research)

Toida, Masaru*; Suyama, Yasuhiro*; Mori, Takayuki*; Inaba, Takeshi*; Sasakura, Takeshi*; Atsumi, Hiroyuki*; Masumoto, Kazuhiko*; Kobayashi, Ichizo*; Iwano, Keita*; Furuichi, Mitsuaki*; et al.

JAEA-Research 2007-065, 210 Pages, 2007/09

JAEA-Research-2007-065-1.pdf:28.82MB
JAEA-Research-2007-065-2.pdf:42.37MB
JAEA-Research-2007-065-3.pdf:24.46MB
JAEA-Research-2007-065-4.pdf:48.78MB

"Geoscientific research" at the Tono Area is developing site investigation, characterization and assessment techniques for understanding of geological environment. Their important goals are to establish a methodology for analyzing uncertainties in heterogeneous geological environment and to develop investigation techniques for efficiently reducing the uncertainties. The current study proposes a new approach where all the possible options in the models and data-sets, which cannot be excluded in the light of the evidences available, are identified. This approach enables uncertainties associated with the understanding at a given stage of the site characterization to be made explicitly using an uncertainty analysis technique based on Fuzzy geostatistics. This approach supports the design of the following investigation stage and reduces the uncertainties efficiently. In FY H16 the technique has been tested through geological modelling and groundwater analyses with Tono Area case based on current knowledge, to demonstrate its applicability and to compile the knowledge / information required to describe the H17 report. This report can be summarized as follows: (1) The knowledge / information required to describe the heterogeneous characteristics was compiled and connected to uncertainties associated with the characterization of a geological environment using a synthesis diagram. (2) Methodologies for assignment and screening of parameters were developed by using Evidential Support Logic (ESL). (3) Applicability of the techniques could be confirmed with Tono Area case. (4) This report proposed a new methodology that integrates the technique into JAEA ordinary technique to good advantage in the geoscientific research project.

JAEA Reports

Study for Evaluation of Performance of Sealing Technique

Toida, Masaru*; Sasakura, Takeshi*; Atsumi, Hiroyuki*; Masumoto, Kazuhiko*; Tanaka, Toshiyuki*; Suyama, Yasuhiro*; Kobayashi, Ichizo*

JNC TJ8400 2004-023, 146 Pages, 2005/02

JNC-TJ8400-2004-023.pdf:11.18MB

To establish sealing technique suitable for geological environmental conditions of Japan, it is necessary to obtain data related with this sealing function through laboratory tests and in-situ tests. It also is necessary to put these data to practical use and to establish the estimating method of the sealing technique.Tunnel sealing experiment, which has been carried out as collaboration between JNC and AECL at URL of AECL Canada, is progressing in the final stage and fundamental data relating with the sealing function has almost obtained. This report deals with the total data processing and interpretation of the sealing experiment, as well as the numerical analysis and interpretation on tracer test results. Conceptual plans of the experiment to confirm the performance of tunnel sealing technique in a sedimentary rock are also discussed.

JAEA Reports

The laboratory test of dielectric constant of the rock core piece in Tono mine

Toida, Masaru*; Atsumi, Hiroyuki*; Nagoya, Kaoru*; Suyama, Yasuhiro*

JNC TJ7440 2005-070, 279 Pages, 2004/03

JNC-TJ7440-2005-070.PDF:22.63MB

no abstracts in English

JAEA Reports

Assessment of unsaturated zone with ground penetrating radar with modulating frequency in Tono mine

Toida, Masaru*; Atsumi, Hiroyuki*; Nagoya, Kaoru*; Suyama, Yasuhiro*

JNC TJ7400 2005-057, 113 Pages, 2004/03

JNC-TJ7400-2005-057.PDF:20.78MB

In this study, in order to conduct all unsaturated territory investigation techniques in the same test site, and to present the result of estimations which interpolate mutually, the continuous wave radar between the hole, and the pore water pressure measurment near the drift wall were executed, in the NATM gallery.

JAEA Reports

Analytical Assessment of Full-Scale Demonstration of Sealing Technique in Canadian Geological Disposal Facility

Toida, Masaru*; Sasakura, Takeshi*; Atsumi, Hiroyuki*; Suyama, Yasuhiro*; Kobayashi, Ichizo*; Kawabata, Junichi*; Ito, Keijiro*

JNC TJ8400 2003-088, 254 Pages, 2004/02

JNC-TJ8400-2003-088.pdf:9.59MB

To establish sealing technique suitable for geological environmental conditions of Japan, it is necessary to obtain data related with this sealing function through laboratory tests and in-situ tests. It also is necessary to put these data to practical use and to establish the estimating method of the sealing technique. Tunnnel sealing experiment, which has been carried out as a joint research between JNC and AECL at URL of AECL Canada, is arriving the final stage and fundamental data relating with the sealing function has almost obtained. This report deals with the total data processing and interpretation of the sealing test, as well as the numerical analysis and interpretation on tracer test results. Concrete plans for the disassembling and sampling of clay and concrete plugs, which is important for the evaluation of function of the sealing system, is also discussed.

JAEA Reports

Assessment of Heterogeneous Geological Environment at Tono; A Technical Report

Toida, Masaru*; Suyama, Yasuhiro*; Inaba, Takeshi*; Sasakura, Takeshi*; Atsumi, Hiroyuki*; Tanaka, Toshiyuki*; Kobayashi, Ichizo*; Iwano, Keita*; Furuichi, Mitsuaki*

JNC TJ7400 2004-017, 521 Pages, 2004/02

JNC-TJ7400-2004-017.pdf:188.01MB

"Geoscientific research" at Tono is developing site investigation, characterization and assessment techniques for understanding of geological environment. Their important themes are to establish a methodology for analyzing uncertainties in heterogeneous geological environment and to develop investigation techniques for reducing the uncertainties efficiently. The current study proposes a new approach where all the possible options in the models and data-sets that cannot be excluded in the light of the evidence available is identified. This approach enables uncertainties associated with the understanding at a given stage of the site characterization to be made explicitly using an uncertainty analysis technique based on Fuzzy geostatistics. This, in turn, supports the design of the following investigation stage to reduce the uncertainties efficiently. In this report the technique has been tested through geological modelling and groundwater analysis with Tono area case based on current knouledge, to demonstrate its applicability. This report summarizes as follows: (1)It is possible to quantify the uncertainties with Tono area case based on current knouledge using the technique. (2)Based on sensitivity analyses, it is possible to support designs of the following investigation stage to reduce the uncertainties efficiently. (3)The methodology of the technique has been developed with Tono area case. (4)The above could evaluate its applicability and propose further issues for synthesis of the methodology.

JAEA Reports

Assessment of Unsaturated Zones with Ground Penetrating Radar with Modulating Frequency in Tono Mine

Toida, Masaru*; Suyama, Yasuhiro*; Kaoru, Nagoya*; Atsumi, Hiroyuki*

JNC TJ7440 2003-001, 92 Pages, 2003/03

JNC-TJ7440-2003-001.pdf:5.66MB

The TDR (Time Domain Reflectmetry) wave analysis method has been developed for measuring unsaturated zones by TGC in Tono mine. The new packer type probe of the TDR wave analysis method has already been made by TGC. But it is impossible for the TDR wave analysis method to estimate distribution of unsaturated zones between boreholes. In the meantime, to overcome the reached penetration depth of the sedimentary rock, the ground penetrating radar with modulating frequency was developed and could have the ability of interpretation of water content distribution from electromagnetic velocity. This report summarizes as follows: 1)An electromagnetic wave tomography with modulating frequency could measure the dielectric constant distribution with a good correlation between the tomography and the TDR wave method at the second measurement gallery. Therefore it recognized that the tomography has a high possibility to interpolate the TDR wave method's results between boreholes. 2)The ground penetrating radar with modulating frequency could measure the dielectric constant, which has a good relationship with water content distribution, at the NATM gallery. Therefore it recognized that the radar has a high possibility to get information concerning water content distribution.

JAEA Reports

Assessment of Heterogeneous Geological Environment Using Geostatistical Techniques; A Technical Report

Toida, Masaru*; Suyama, Yasuhiro*; Shiogama, Yukihiro*; Atsumi, Hiroyuki*; Abe, Yasunori*; Furuichi, Mitsuaki*

JNC TJ7410 2003-004, 351 Pages, 2003/02

JNC-TJ7410-2003-004.pdf:47.52MB

"Geoscientific research" at Tono are developing site investigation and assessment techniques in geological environment. One of their important themes is to establish rational methodology to reduce uncertainties associated with the understanding of geological environment, which often exhibits significant heterogeneity. Purpose of this study is to identify and evaluate uncertainties associated with the understanding of geological environment. Because it is useful to guide designing effective site investigation techniques to reduce the uncertainty. For this, a methodology of the uncertainty analysis concerning the heterogeneous geological environment has been developed. In this report the methodology has also been tested through an exercise attempted in Tono area to demonstrate its applicability. This report summarizes as follows: 1)The exercise shows that the methodology considered 'variability' and 'ignorance' can demonstrate its applicability at three-dimensional case. 2)The exercise shows that the methodology can identity and evaluate uncertainties concerning ground water flow associated with performance assessment. 3)Based on sensitivity analysis, it is possible for the methodology to support designs of the following stage investigations to reduce the uncertainties efficiently.

JAEA Reports

Study on synthesis of Geologocal Environment at Horonobe area; A Technical review

Toida, Masaru*; Suyama, Yasuhiro*; Shiogama, Yukihiro*; Atsumi, Hiroyuki*; Abe, Yasunori*; Furuichi, Mitsuaki*

JNC TJ5400 2003-003, 460 Pages, 2003/02

JNC-TJ5400-2003-003.pdf:81.56MB
JNC-TJ5400-2003-003(errata).pdf:0.08MB

In this study, through development of cnceptual models of geological environment based on those data, the flows from data collection to modeling, which have been constructed independently for each geological environment of geology / geological structure , hydrogeology, geochemistry of groundwater and rock mechanics , were synthesized , adn a systematic approach includeing process from investigation of geological environment to its modeling was established , which is expected to ensure objectivity and raceability of the design and safety assessment of a disposal system.

JAEA Reports

Full-scale Demonstration of Sealing Technique in Geological Disposal(III)

Toida, Masaru*; Shiogama, Yukihiro*; Atsumi, Hiroyuki*; Suyama, Yasuhiro*; Kawabata, Junichi*; Ito, Keijiro*; Okutsu, Kazuo*

JNC TJ8400 2003-023, 60 Pages, 2003/01

JNC-TJ8400-2003-023.pdf:2.48MB

To establish sealing technique suitable for geological environmental conditions of Japan, it is necessary to obtain data related with this sealing function through laboratory tests and in-situ tests. It also is necessary to put these data to practical use and to establish the estimating method of the sealing technique. This report deals with the sealing function tests under heating condition of supplying water, following the pressurized tests of supplying water at the AECL in Canada until last year. These test results are reported here together with the data, interpretation and analysis of tracer test results. Information arrangement for the establishment of estimation method of sealing function is also performed.

JAEA Reports

Full-scale Demonstration of Sealing Technique in Geological Disposal(III)

Toida, Masaru*; Shiogama, Yukihiro*; Atsumi, Hiroyuki*; Suyama, Yasuhiro*; Kawabata, Junichi*; Ito, Keijiro*; Okutsu, Kazuo*

JNC TJ8400 2003-022, 213 Pages, 2003/01

JNC-TJ8400-2003-022.pdf:13.05MB

To establish sealing technique suitable for geological environmental conditions of Japan, it is necessary to obtain data related with this sealing function through laboratory tests and in-situ tests. It also is necessary to put these data to practical use and to establish the estimating method of the sealing technique. This report deals with the sealing function tests under heating condition of supplying water, following the pressurized tests of supplying water at the AECL in Canada until last year. These test results are reported here together with the data, interpretation and analysis of tracer test results. Information arrangement for the establishment of estimation method of sealing function is also performed.

JAEA Reports

None

Toida, Masaru*; Shiogama, Yukihiro*; Atsumi, Hiroyuki; Masumoto, Kazuhiko*; *; Abe, Yasunori*; Furuichi, Mitsuaki*

JNC TJ7440 2000-006, 137 Pages, 2000/02

JNC-TJ7440-2000-006.pdf:3.55MB

no abstracts in English

Oral presentation

Consideration of acceptance level of gas bubbles entrained at free surface in reactor vessel of fast reactor

Tatsumi, Eisaku*; Takata, Takashi*; Yamaguchi, Akira*; Ohshima, Hiroyuki; Ito, Kei; Kamide, Hideki

no journal, , 

In order to estimate inert gas behavior in a circulating system of a sodium-cooled fast reactor, the plant dynamics code called the VIBUL code has been employed. In this study, the VIBUL was used to evaluate the effect of gas entrainment phenomena at free surface in upper plenum on the void fraction at core inlet.

Oral presentation

Development of methodlogy for the groundwater monitoring in natural barrier

Tanaka, Mayumi*; Toida, Masaru*; Atsumi, Hiroyuki*; Seno, Shoji*; Nakajima, Makoto*

no journal, , 

Ground penetrating radar with modulating frequency combined with static pressure measurement using hydrotesting tool for damaged zone, which were developed by Kajima coporation, has been applied to the drift of Tono mine for the evaluation of hydraulic characteristics of the damaged zone around the drift.

Oral presentation

Solute transport analysis using discrete fracture network model, 3

Hosoya, Shinichi*; Seno, Shoji*; Nakajima, Makoto*; Atsumi, Hiroyuki*; Ishibashi, Masayuki; Morikawa, Keita; Onoe, Hironori; Kunimaru, Takanori

no journal, , 

Discrete Fracture Network (DFN) model provides the basis of groundwater flow analysis and solute transport analysis for crystalline rock. Due to its complexity, it is difficult to estimate how the input parameters influence the result of the analysis. In this study, using the data obtained in the Mizunami Underground Research Laboratory (MIU) project conducted by Japan Atomic Energy Agency (JAEA), we examined how the modeling methodology influenced the result of groundwater flow analysis and solute transport analysis.

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