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Tachi, Yukio; Aoyagi, Kazuhei; Ozaki, Yusuke; Hayano, Akira; Ono, Hirokazu; Takeda, Masaki; Mochizuki, Akihito; Dei, Shuntaro; Minaka, Jumpei; Murakami, Hiroaki; et al.
NEA/NE(2025)20 (Internet), 118 Pages, 2025/11
Hagihara, Koji*; Mayama, Tsuyoshi*; Yamasaki, Michiaki*; Harjo, S.; Tokunaga, Toko*; Yamamoto, Kazuki*; Sugita, Mika*; Aoyama, Kairi*; Gong, W.; Nishimoto, Soya*
International Journal of Plasticity, 173, p.103865_1 - 103865_21, 2024/02
Times Cited Count：52 Percentile：99.12(Engineering, Mechanical)Kondo, Keiji; Tsusaka, Kimikazu; Inagaki, Daisuke; Sugita, Yutaka; Kato, Harumi*; Niunoya, Sumio*
Dai-13-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM), p.583 - 588, 2013/01
no abstracts in English
Tsusaka, Kimikazu; Sugita, Yutaka; Kudo, Hajime
Doboku Gijutsu, 67(4), p.74 - 80, 2012/04
In this paper, the authors described a summery of the construction of the Horonobe Underground Research Laboratory and the technical features from the viewpoint of civil engineering. There are three important technical points in the construction. The first is the construction of shafts at great depth (500 m below the ground surface) through the soft sedimentary rocks. The second is pre-excavating grouting operation to fracture zone with high permeability. The third is to build gas-sensing system of methane dissolving in the groundwater in the drifts.
Sugita, Yutaka*; Takahashi, Yoshiaki*; Uragami, Manabu*; Kitayama, Kazumi*; Fujita, Tomoo; Yui, Mikazu
JAEA-Research 2007-023, 70 Pages, 2007/03
JAEA-Research-2007-023.pdf:26.16MB
The sealing performance of a repository is very important for the safety assessment of the geological disposal system for high-level radioactive waste. NUMO and JAEA set up a technical commission to investigate sealing technology in a repository in 2004 following a cooperation agreement between these two organisations. The objectives of this commission were to present a concept of sealing performance required in the disposal system and to direct future R&D for design requirements of closure components (backfilling material, clay plug, etc.). Hydraulic analyses on tunnel intersections were carried out during the first year in 2004. This was expanded into a hydraulic analysis of a complete disposal panel with all tunnels during the second year in 2005. Since the model structure in 2005 was more complicated than the one used in 2004, the concept of equivalent permeability was adopted in and around each tunnel in the hydraulic analyses. Parameters used in the hydraulic analyses were installation positions of clay plugs, permeability of the backfilling material, permeability of disposal tunnel and directions of hydraulic gradient to estimate influences to the analytical results preliminary. Analytical results showed that flow rate in a disposal tunnel was influenced by directions of hydraulic gradient, installation of the clay plug at the both ends of each disposal tunnel and permeability of the main tunnel.
Sugita, Yutaka; Fujita, Tomoo; Takahashi, Yoshiaki*; Kawakami, Susumu; Umeki, Hiroyuki; Yui, Mikazu; Uragami, Manabu*; Kitayama, Kazumi*
Physics and Chemistry of the Earth, 32(1-7), p.32 - 41, 2007/00
Times Cited Count：6 Percentile：19.30(Geosciences, Multidisciplinary)The H12 repository concept for vitrified high-level radioactive waste was developed based on a multi-barrier system with the emphasis on robust engineered barrier performance to ensure its feasibility for a wide range of geological conditions typically observed in Japan. The buffer is clay-based and plays a very important role in the engineered barrier system (EBS). The decision to use a volunteer siting process requires maximum flexibility of the repository concept to allow it to be adapted to potential sites and hence a wide range of variants of the basic H12 repository design has been developed. In order to evaluate the feasibility and the applicability of different repository options to specific siting environments, NUMO has established a set of "design factors" which classify the aspects that need to be considered when evaluating the pros and cons of different repository options. A Na-type bentonite from Japan is used as the reference material for all clay-based repository components (buffer, backfill, clay plug, etc.). The characteristics of this bentonite (thermal, mechanical, chemical, hydraulic) have been examined with consideration of various practical constraints (limitation on the repository footprint, the influence of saline water, the interaction of hyperalkaline leachates and practical working environment, etc.). Clay-based seals, which close off the tunnels after emplacement of the EBS, may also be key components for assessment of the repository. Full analyses considering all engineered barrier components (buffer, backfill, clay plug, concrete lining, tunnel, concrete plug, host rock) that may be used in a repository will be an essential future task. As a first step towards this goal, a numerical analysis focusing on hydraulic behaviour at the intersections of the disposal tunnels and the main tunnel is presented to illustrate how the design requirements of clay-based seals can be determined.
Sugita, Yutaka*; Fujita, Tomoo; Takahashi, Yoshiaki*; Kawakami, Susumu; Umeki, Hiroyuki; Yui, Mikazu; Uragami, Manabu*
JNC TN8400 2005-016, 49 Pages, 2005/09
JNC-TN8400-2005-016.pdf:5.45MB
The sealing performance of a repository should be considered in the safety assessment of the geological disposal system of the high level radioactive waste. Nuclear Waste Management Organization of Japan and Japan Nuclear Cycle Development Institute are examining the sealing performance of the closure components (backfilling material and clay plug) to present the concept on the sealing performance required to the disposal system, and to develop the direction for the future R&D programme for the design requirements of the closure components of the presented concepts.The first step of this examination reviewed the current status of the domestic and the international sealing technologies, summarized the repository components and the repository environments, and performed the hydraulic analysis considering components on the intersections of a main tunnel and a disposal tunnel in a disposal panel and in and around the engineered barrier system (EBS). Since all tunnels connect in the underground facility, understanding of hydraulic behaviour at the intersections of the tunnels is the important issue to estimate migration of radionuclides from the EBS, and to evaluate the required sealing performance for the disposal system. The considering components in the analysis model are the intersections of the disposal tunnel and the main tunnel, the waste package, the EBS, the backfilling material, the clay plug, the concrete plug, the excavated disturbed zone, the tunnel lining and the host rock. Alteration of the concrete material (tunnel lining and concrete plug) is described as variation of the hydraulic conductivity of it. Sites of emplacement of the clay plug are the disposal tunnel and the main tunnel. No clay plug condition is also analysed. Effect of the clay plug is discussed by the results of these analyses.
Kurihara, Yuji; Yui, Mikazu; Tanai, Kenji; Kawakami, Susumu; Sugita, Yutaka; Taniguchi, Naoki; Hirai, Takashi
JNC TN8400 2004-006, 59 Pages, 2004/04
JNC-TN8400-2004-006.pdf:5.97MB
Following studies have been done in this papers in order to apply the technologies based on H12 report to the actual geological conditions of Horonobe underground research laboratory. 1.reconsidering the process of repository design, 2. arrangement of the relations between geological conditions and the performance of engineering barrier systems, 3.present the appropriate form of geological informations, 4.study on the stability of deposition hall.
Kurihara, Yuji; Yui, Mikazu; Tanai, Kenji; Kawakami, Susumu; Sugita, Yutaka; Taniguchi, Naoki; Hirai, Takashi
JNC TN8400 2004-002, 58 Pages, 2004/04
JNC-TN8400-2004-002.pdf:2.38MB
In this paper, the items of in-situ experiments at Horonobe URL with respect to the technical issues about reliability of long-term behavior of engineered barrier system were extracted. And the concepts of the experiments were studied from several points of view such as verification of models and getting the actual behavior. Extracted items of the in-situ experiments are as follows. Coupled Phenomena Test (THMC Test), Buffer & Rock Creep Test, Gas Migration Test, Over-pack Corrosion Test, High-pH Influence Test, Low Alkaline Concrete Execution Test, Engineering-Barrier Emplacement Test, Tunnel Plugging Test.
Kurihara, Yuji; Fujita, Tomoo; Kawakami, Susumu; Jintoku, Takashi; Yui, Mikazu; Sugita, Yutaka
JNC TN8400 2003-053, 32 Pages, 2004/03
JNC-TN8400-2003-053.pdf:0.41MB
In previous JNC tequnichal reports, from a view point of long-term safety on geological disposal of high level radioactive waste, the items which should guarantee the performance of each element of the repository were extracted, and it was shown how to guarantee the performance about these items. Furthermore, future R&D requirements were extracted. In this report, the status of each subject in JNC was reported.
Sugita, Yutaka; Kawakami, Susumu; Taniguchi, Naoki; Yui, Mikazu
JNC TN8400 2003-038, 27 Pages, 2004/02
JNC-TN8400-2003-038.pdf:1.29MB
Regarding installation of buffer material for geological disposal of the high-level radioactive waste, various installation techniques are studied. Block type installation technique which uses high density pre-compacted block has benefits and problems. Benefits are that quality assurance reaches high level because block is compacted before move to the disposal facilities, and that high performance machine can product the higher density blocks. Problems are that flexibility at the underground facilities is low, and that assessment of influence of the gaps between blocks until the swollen blocks fill the gaps is required.Therefore, barrier performance of the block type buffer material was assessed by results of fundamental experiments of filling gap function, corrosion behavior of carbon steel overpack under conditions of the gap coexistence, shear tests and the permeability tests.From the results of these tests, block type buffer material will act ideal function under consideration of the expected environment and adequate materials and so on.
Kawakami, Susumu; Yui, Mikazu; Kurihara, Yuji; Jintoku, Takashi; Sugita, Yutaka
JNC TN8400 2003-037, 26 Pages, 2004/02
JNC-TN8400-2003-037.pdf:1.33MB
In order to contribute to the safety standards and guidelines upon which a administration decides, examination for clarifying how to reflect the result obtained by future R&D was performed in other reports, as the JNC technical reports. In those reports, from a viewpoint of the long-term safety on geological disposal of high-level radioactive waste, the items which should guarantee the performance of each element of the repository were extracted, and it was shown how to guarantee the performance about these items. Furthermore, future R&D requirements were extracted. In this report, the status of each subject in JNC was reported.
Sugita, Yutaka; Kawakami, Susumu; Yui, Mikazu; Makino, Hitoshi; Sawada, Atsushi; Mihara, Morihiro; Kurihara, Yuji
Genshiryoku Bakkuendo Kenkyu, 10(1), p.103 - 112, 2004/00
None
Sugita, Yutaka; Kurihara, Yuji; Kawakami, Susumu; Jintoku, Takashi; Yui, Mikazu
JNC TN8400 2003-015, 34 Pages, 2003/05
JNC-TN8400-2003-015.pdf:2.65MB
In order to contribute to the safety standards and guidelines upon which a governmental administration decide, examination for clarifying how to reflect the result obtained by future R&D was performed. From a view point of long-term safety on geological disposal, the items which should guarantee the performance of each element which constitutes disposal institutions (by this report, they are the backfill, the plug, the tunnel, and the pit) were extracted, and it was shown what a performance guarantee is concretely offered about these items. Furthermore, based on H12 report as a situation of present R&D for a method of a performance guarantee, the subjects considered that a future R&D is required were extracted.
Sugita, Yutaka; Kawakami, Susumu; Yui, Mikazu; Makino, Hitoshi; ; Kurihara, Yuji; Mihara, Morihiro
JNC TN8400 2003-010, 44 Pages, 2003/04
Regarding closure technology of undergound facilities in geological disposal of the HLW in H12 rport, the fundamental concept that closure technology has no impact against the engineered barrier system(EBS) was described. Performance Assessment(PA) has been performed without considering of the barrier function of closure elements. Following H12 report, the various in-situ data of the closure elements (ex. plug, backfill) have been obtained. Therefore, we considered that the PA of the EBS considering the expecting performance of the closure elements from the view points of both the engineering technology and the PA should be examined. First, the characteristics of rock mass and the function of the closure elements were summarized. Then, the closure scenario was developed preliminarily based on hydrological analysis between a hydraulic fracture and a disposal panel, the fault tree analysis, and so on.
Kawakami, Susumu; Sugita, Yutaka; Kurihara, Yuji; Jintoku, Takashi; Taniguchi, Naoki; Yui, Mikazu
JNC TN8400 2002-026, 42 Pages, 2003/03
JNC-TN8400-2002-026.pdf:12.1MB
In order to contribute to the safety standards and guidelines upon which a administration decides, examination for clarifying how to reflect the result obtained by future R%D was performed. From a viewpoint of the long-term safety on geological disposal, the items which should guarantee the performance of each element which constitutes disposal institutions (by this report, they are the overpack and the buffer material) were extracted, and it was shown what a performance guarantee is concretely offered about these items. Furthermore, based on the H12 report as a situation of present R&D for a method of a performance guarantee, the subjects considered that a future R&D is required were extracted. Moreover, the items of a safety standard and guideline were assumed, and the relation between these items and a performance guarantee items was arranged. One arrangement for clarifying whether to be reflected in the safety regulations and guidelines whose R%D subjects extracted from the performance guarantee items was shown.
Ito, Akira; Yui, Mikazu; Sugita, Yutaka; Kawakami, Susumu
Proceedings of International Conference on Coupled T-H-M-C Processes in Geo-systems; Fundamentals, Modelling, Experiments and Applications (GeoProc 2003), 346 Pages, 2003/00
None
Sugita, Yutaka; Yui, Mikazu
JNC TN8450 2002-005, 23 Pages, 2002/10
JNC-TN8450-2002-005.pdf:0.59MB
This report summarizes the dataset of the dry density and water content of the emplaced buffer on the full-scale laboratory tests described in JNC Technical Report (TN8430 98-003), "Verification of buffer material emplacement technique in coupled T-H-M Experiment at Kamaishi In-situ Experiment".
Sugita, Yutaka; Yui, Mikazu
JNC TN8450 2001-010, 40 Pages, 2002/02
JNC-TN8450-2001-010.pdf:1.11MB
This report summary the dataset of the relationship between unconfined compressive strength and various parameters of the rock mass described in supporting report 2; repository design and engineering technology of second progress report (H12 report) on research and development for the geological disposal of HLW in Japan.
Sugita, Yutaka; Yui, Mikazu
JNC TN8450 2001-007, 16 Pages, 2002/02
JNC-TN8450-2001-007.pdf:0.78MB
This report summary the dataset of the relationship between unconfined compressive strength and tensile strength of the rock mass described in supporting report 2; repository design and engineering technology of second progress report (H12 report) on research and development for the geological disposal of HLW in Japan.
