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JAEA Reports

Study on engineering technologies in the Mizunami Underground Research Laboratory; FY2008 (Contract research)

Ijiri, Yuji*; Noda, Masaru*; Sasakura, Takeshi*; Nobuto, Jun*; Matsui, Hiroya; Mikake, Shinichiro; Hashizume, Shigeru

JAEA-Technology 2012-018, 288 Pages, 2012/07

JAEA-Technology-2012-018.pdf:19.13MB

The researches on engineering technology in the Mizunami Underground Research Laboratory plan consists of (1) research on engineering technology at a deep underground, and (2) research on engineering technology as a basis of geological disposal. The former research mainly aimed in this study are categorized in (a) development of design and construction planning technologies, (b) development of construction technology, (c) development of countermeasure technology, (d) development of technology for security. In this study, the researches on engineering technology are proceeded in these four categories by using data measured down to GL-300m during construction as a part of the second phase of the MIU plan.

Journal Articles

Full-scale experimental study on mechanical behavior of a clay plug under HLW disposal conditions

Sasakura, Takeshi*; Masumoto, Kazuhiko*; Toida, Masaru*; Fujita, Tomoo; Sugita, Yutaka

Proceedings of 9th International Conference on Geo-environmental Engineering (GEE 2010), p.47 - 56, 2010/05

High level radioactive waste is to be vitrified, and after some period of storage for cooling, put into engineered barriers such as metal canister, overpack and buffer material, and finally disposed of in the stable geology at the depth of 300 m or deeper to isolate from human environment for a long period of time in Japan. The geological repository consists of surface facilities and subsurface facilities; the later, mainly consists of tunnels for transportation and waste emplacement, will be closed using sealing technologies such as backfilling, plugging, and grouting after emplacement of the waste to prevent seepage of radionuclides for a long period of time. Effectiveness of these sealing technologies, however, has not been well demonstrated in-situ worldwide, and the technologies may be considered in the stage of research and development. Therefore, in this paper, the in-situ tunnel sealing test performed at Canada to demonstrate the effectiveness of the plug under crystalline rock environment was overviewed focusing on the plug. Then behavior of the plug, particular of mechanical behavior, during sealing tests, observation result of dismantled plug were reviewed and points to be addressed for establishing the clay plug technology were identified. Because the procedure of this tunnel sealing test and hydraulic sealing performance of the plug has already been precisely reported by Fujita et al. (2007), outline of the test is briefly summarized and mechanical behavior of the plug was focused. As a result, effectiveness of conventional construction technology of a plug was shown, the behavior of a plug during the pressurization test was clarified and important points to be addressed for establishing the clay plug technology were identified.

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

Studies on Mechanical Behavior of Materials Employed in Engineered Barrier for Development of the Constitutive Model

Toida, Masaru*; Sasakura, Takeshi*; Yokozeki, Kosuke*; Kobayashi, Ichizo*; Watanabe, Kenzo*; Ashizawa, Ryoichi*

JNC TJ8400 2004-036, 310 Pages, 2005/03

JNC-TJ8400-2004-036.pdf:3.76MB

To integrate the system for evaluation of long-term hydraulic condition in near field of TRU waste disposal, the engineered barrier, which consists of bentonite buffer and cementitious materials, was employed in the series of laboratory tests. On the bentonite buffer, with the aim of investigating of the effect of (i)interlayer cation in bentonite, (ii)content of siliceous sand and (iii)the ionic strength of ground water on its mechanical and hydraulic properties, series of laboratory tests were conducted. The same lot of bentonite was used in the series of tests to obtain consistent data. In addition, the swelling test of the laminated bentonite with caliumization front was conducted for verification of the proposed constitutive model. On cementitious materials, the altered specimen that produced immersing was investigated the water permeation and also characteristics. The hardened cement paste specimens with W/C=40 to 105% were immersed into deionized water and alteration behavior under diffusion condition was investigated.

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

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:96.64MB

"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

Studies on Mechanical Behavior of Bentonite for Development of the Constitutive Model II

Sasakura, Takeshi*; Kuroyanagi, Mikio*; Okamoto, Michitaka*; Kobayashi, Ichizo*

JNC TJ8400 2003-048, 180 Pages, 2003/02

JNC-TJ8400-2003-048.pdf:9.43MB

Series of laboratory tests were conducted to investigate the effect of 1)cation exchange of Na-bentonite for Ca ion, and 2)the swelling behavior of bentonite, on its mechanical and hydraulic properties.

JAEA Reports

Studies on mechanical behavior of bentonite for development of the constitutive model

Sasakura, Takeshi*; Kuroyanagi, Mikio*; *

JNC TJ8400 2002-025, 182 Pages, 2002/02

JNC-TJ8400-2002-025.pdf:10.59MB

To integrate the system for evaluation of long-term hydraulic condition in near field of TRU waste disposal, series of laboratory tests were conducted to investigate the effect of (a)cation exchange of Na-bentonite for Ca ion, and (b)the swelling behavior of bentonite, on its mechanical and hydraulic properties. For the purpose of this study, same lot of bentonite was used in a series of tests to obtain consistent data. A constitutive model of clayey materials, called Cam-clay model, was expanded conceptually to express the effects mentioned above. The research results of this year are summarized below; (1)Some basic properties such as cation exchange capacity, particle density, grain size distribution, compaction-characteristics and water content were obtained. To examine the effect of previous swelling history of bentonite on its swelling characteristics and hydraulic and mechanical properties, specimens, which generated swelling deformation to various volumetric strain levels, were specially prepared and used in the following tests. Swelling pressure tests, swelling deformation tests, permeability tests were conducted to observe one dimensional swelling characteristics and hydraulic properties of Na-bentonite and Ca-bentonite. High-pressured triaxial consolidated-undrained (CU) compression tests and high-pressured consolidation tests were also carried out to investigate the compression, swelling, and shearing behavior of each type of bentonite. (2)As indicated in previous studies, two important phenomena (a)bentonite possesses remarkable swelling capacity, (b)cation exchange of Na-bentonite for Ca-ion lead increasing of hydraulic conductivity, were confirmed in the test results. From the swelling deformation test results and published data, it was found that swelling capacity of bentonite has no dependency on previous swelling history and it could be easily expressed as a function of void ratio e. It was also confirmed that swelling pressure and water ...

Oral presentation

The Project for grouting technology development for the high level radioactive waste repository, 10; In-situ test plan of developed techniques

Kobayashi, Yasushi; Sugita, Yutaka; Izumi, Atsushi; Toida, Masaru*; Sasakura, Takeshi*

no journal, , 

no abstracts in English

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