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Osawa, Hideaki
Gijutsushi "Chubu", (15), p.40 - 47, 2025/03
This paper introduces the history of the development of borehole investigation techniques at the Tono Geoscience Center of the Japan Atomic Energy Agency (JAEA), which started in 1986, as one of the research of geological environmental characteristics.
Mitsuguchi, Takehiro; Okabe, Nobuaki*; Kokubu, Yoko; Matsuzaki, Hiroyuki*
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 31(2), p.96 - 110, 2024/12
Geological disposal of high-level radioactive waste requires not only selecting sites appropriate for the waste repository, where its isolation ability would not be damaged by natural phenomena for several tens of thousands of years, but also rationally constructing the disposal system depending on site-specific geological environments and their anticipated long-term variability. Recently, elemental/isotopic compositions of underground fluids (deep groundwaters, hot/cold spring waters, brines associated with oil and natural gas reservoirs, and so on) in Japan have been studied for evaluating the long-term stability of the geological environments of this country. Iodine and its radioactive isotope 
I (half-life = 15.7 million years) are included in the subjects of the study. The current review paper provides overviews of (i) the iodine content and iodine-129/127 ratio (I/
I ratio) of various materials in Earth's surface layers, (ii) relevant sample pretreatments and measurements, and (iii) I/I data of the underground fluids in Japan, then gives (iv) some interpretations of the fluid I/I data, along with their problems and uncertainties, and (v) some implications towards evaluating the long-term stability of geological environments.
Yuguchi, Takashi*; Kato, Takenori*; Ogita, Yasuhiro; Watanabe, Minori*; Yamazaki, Hayato*; Kato, Asuka*; Ito, Daichi*; Yokoyama, Tatsunori; Sakata, Shuhei*; Ono, Takeshi*
Journal of Asian Earth Sciences, 265, p.106091_1 - 106091_13, 2024/04
Times Cited Count：2 Percentile：50.98(Geosciences, Multidisciplinary)Osawa, Hideaki
Gijutsushi "Chubu", (12), p.34 - 41, 2023/09
This introduces current status of Toki Geochronology Research Laboratory, Tono Geoscience Center, Japan Atomic Energy Agency.
Geological Disposal Research and Development Department
JAEA-Evaluation 2022-007, 81 Pages, 2022/11
JAEA-Evaluation-2022-007.pdf:2.06MB
JAEA-Evaluation-2022-007-appendix(CD-ROM).zip:37.06MB
Japan Atomic Energy Agency (JAEA) consulted the advisory committee, "Evaluation Committee on Research and Development (R&D) Activities for Geological Disposal of High-Level Radioactive Waste", for post- and pre-review assessment of R&D activities on high-level radioactive waste disposal in accordance with "General Guideline for the Evaluation of Government Research and Development (R&D) Activities" by the Cabinet Office, Government of Japan, "Guideline for Evaluation of R&D in Ministry of Education, Culture, Sports, Science and Technology" and JAEA's "Regulation on Conduct for Evaluation of R&D Activities". In response to JAEA's request, the Committee reviewed mainly the progress of the R&D project on geological disposal, the relevance of the project outcome and the efficiency of the project implementation during the period of the current and next plan. This report summarizes the results of the assessment by the Committee with the Committee report attached.
Sakai, Toshihiro; Hayano, Akira
JAEA-Data/Code 2021-010, 243 Pages, 2021/10
JAEA-Data-Code-2021-010.pdf:62.15MBJAEA-Data-Code-2021-010-appendix1(CD-ROM).zip:95.55MBJAEA-Data-Code-2021-010-appendix2(CD-ROM).zip:152.69MBJAEA-Data-Code-2021-010-appendix3(CD-ROM).zip:25.48MB
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formations at Horonobe, northern Hokkaido. The project consists of two major research areas, "Geoscientific Research" and "R&D on Geological Disposal", and proceeds in three overlapping phases, "Phase I: Surface-based investigation", "Phase II: Construction" and "Phase III: Operation". The geological survey has been carried out at the shafts and the galleries in the Phase II. The geological survey was carried out during the excavation cycle, and the data were obtained for each an excavation cross section. This report shows the data which the individual geological data were integrated for the geological survey at the shafts and the galleries from the surface to a depth of 380m.
Sakai, Toshihiro; Ishii, Eiichi
JAEA-Data/Code 2021-009, 13 Pages, 2021/08
JAEA-Data-Code-2021-009.pdf:1.9MBJAEA-Data-Code-2021-009-appendix(CD-ROM).zip:42.79MB
Japan Atomic Energy Agency is performing the Horonobe Underground Research Laboratory Project, which includes a scientific study of the deep geological environment as a basis of research and development for the geological disposal of high level radioactive wastes, in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in the sedimentary rock. The numerical data of 3D geological model in regional-scale was compiled in 2019 as JAEA-Data/Code 2019-007, and then this report updates a part of the numerical data of 3D geological model around the underground facilities.
Onoe, Hironori
JAEA-Data/Code 2020-016, 15 Pages, 2020/11
JAEA-Data-Code-2020-016.pdf:3.12MBJAEA-Data-Code-2020-016-appendix(DVD-ROM).zip:262.52MB
Japan Atomic Energy Agency has been conducting Mizunami Underground Research Laboratory (MIU) Project, which is a broad scientific study of the deep geological environment as a basis of research and development for geological disposal of high-level radioactive waste, targeting in crystalline rock. This report summarized the digital data of local scale and site scale geological model and hydrogeological model constructed in the MIU project and the Regional hydraulic study.
Yuguchi, Takashi*; Ogita, Yasuhiro; Kato, Takenori*; Yokota, Rintaro*; Sasao, Eiji; Nishiyama, Tadao*
Journal of Asian Earth Sciences, 192, p.104289_1 - 104289_16, 2020/05
Times Cited Count：6 Percentile：27.59(Geosciences, Multidisciplinary)Quartz from a granitic pluton is found to have formed through sequential growth events under different mechanisms and crystallization temperatures, which can provide new insights into magmatic processes of granitic magmas that were eventually consolidified into plutons. The events were identified using (1) the description of crystal shape and occurrence, (2) the study of the internal structure with cathodoluminescence (CL), and (3) derivation of the crystallization temperatures based on TitaniQ thermometry. The magmatic quartz crystals from the Toki granite, central Japan, are characterized as having the following internal structures: oscillatory zonation, no-oscillatory zonation with luminescence graduation (gradational zonation), and heterogeneous CL. The quartz crystals with oscillatory zonation were formed in the temperature range of about 800 
C to below 700 C, which is referred to as oscillatory zoning temperature (OZT) conditions. The CL zonation pattern was controlled by the temperature conditions and titanium diffusivity in the melt (magma). The crystallization process of quartz within the Toki granite reveals the cooling processes of the granitic pluton; the lithofacies with a high frequency of oscillatory-zoned quartz underwent slower cooling under the OZT conditions than those in other lithofacies.
Tomita, Jumpei
Zusetsu Nihon No Onsen No, 170 Onsen No Saiensu, P. 111, 2020/03
no abstracts in English
Sakai, Toshihiro; Matsuoka, Toshiyuki
JAEA-Data/Code 2019-007, 29 Pages, 2019/09
JAEA-Data-Code-2019-007.pdf:53.07MBJAEA-Data-Code-2019-007-appendix(CD-ROM).zip:340.04MB
Japan Atomic Energy Agency is performing the Horonobe Underground Research Laboratory Project, which includes a scientific study of the deep geological environment as a basis of research and development for the geological disposal of high level radioactive wastes, in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in the sedimentary rock. This report summarize numerical data of 3D geological model in regional-scale constructed by Maptek
Vulcan.
Shimada, Koji
Chishitsu Gijutsu, (9), p.25 - 40, 2019/09
Today many collaborations are there in Earth-scientific research and development. Structural geology can serve crucial information on tectonic strain at sampling point in Japan, belonging to the circum-Pacific orogenic belt. Visualize of strain estimation would be effective during field geological survey and for better understanding for non-specialist on structural geology. Illustrations decoding mathematical expressions of strain estimation methods are presented here.
Murakami, Hiroaki; Ashizawa, Masaomi*; Tanaka, Kazuhiro*
Oyo Chishitsu, 59(1), p.2 - 12, 2018/04
This study describes the features of fractures and their fillings along with the long-term behavior of their hydrogeological structures in an underground environment based on the results of a geological investigation conducted at an underground facility in northern Kyushu. Fractures were classified into five groups on the basis of fracture orientation: A, B, C, D, and low-angle groups. The genesis of all fractures is the cooling process of granodiorite pluton. Almost all of the water-conducting fractures are included in the B group. Because a number of fracture fillings in the B group are filled by prehnite and crushed fragments of epidote and quartz, the fractures in this group alternated sealing and re-opening. The fracture characteristics in the B group are follow as: accompanying many alteration halos, long trace length, and cutting off other fractures. These results indicate that fractures in the B group have possibly functioned as pathways for groundwater flow in the long term.
Matsukawa, Shun*; Itakura, Kenichi*; Hayano, Akira; Suzuki, Yukinori*
Journal of MMIJ, 133(11), p.256 - 263, 2017/11
LIDAR detects a rock mass surface configurations as a point cloud. DiAna (Discontinuity Analysis) is a Matlab tool which was developed for geo-structural analysis of rock mass discontinuities. DiAna segments a point cloud into bounding boxes to estimate the surface of a rock mass. However, an expert's skills necessary to determine the appropriate size of the bounding boxes for DiAna. We developed the VBS (Variable-Box Segmentation) algorithm to determine the appropriate box size depending on the location of the point cloud and to estimate the surface of a rock mass. The performance of the VBS algorithms was evaluated by comparison with the DiAna algorithm. The results of comparison showed that the VBS algorithm estimated planes more accurately for the reference planes than the DiAna algorithm. Therefore, the VBS algorithm determines appropriate box sizes automatically depending on the location of the point cloud and estimates the surface appropriately.
Komatsu, Tetsuya
Chigaku Zasshi, 125(5), p.661 - 698, 2016/10
The Pamir is a mountain region of the westernmost part of the Himalayan-Tibetan orogen and extends 
300 km from north to south and 300-400 km from west to east. The Pamir lies on a double subduction zone, where two buoyant continental lithospheric plates have subducted several hundred kilometers deep into the asthenosphere. The southern plate is the northward-dipping Hindu Kush slab, and the northern plate is the southward-dipping Pamir slab. This paper reviews recent studies on the Cenozoic tectonic evolution of the Pamir in this unique tectonic setting.
Hama, Katsuhiro; Sasao, Eiji; Iwatsuki, Teruki; Onoe, Hironori; Sato, Toshinori; Fujita, Tomoo; Sasamoto, Hiroshi; Matsuoka, Toshiyuki; Takeda, Masaki; Aoyagi, Kazuhei; et al.
JAEA-Review 2016-014, 274 Pages, 2016/08
JAEA-Review-2016-014.pdf:44.45MB
We synthesized the research results from the Mizunami/Horonobe Underground Research Laboratories (URLs) and geo-stability projects in the second midterm research phase. This report can be used as a technical basis for the Nuclear Waste Management Organization of Japan/Regulator at each decision point from siting to beginning of disposal (Principal Investigation to Detailed Investigation Phase).
Sakai, Toshihiro; Nohara, Tsuyoshi; Ishibashi, Masayuki
JAEA-Research 2016-009, 27 Pages, 2016/07
JAEA-Research-2016-009.pdf:4.05MB
In the Phase II, the geophysical and geological surveys, and the borehole investigation of the research galleries were carried out and the results obtained were used to validate and update the geological model. Through these surveys and analysis work, we confirmed the geological properties and the distribution of model components and evaluated the accuracy of these research methods. This report presents the geological model updated based on the information of the distributions of lithofacies and geological structures at a depth 500m research galleries, and besides, the validity of the geological model of the site scale developed in the Phase I is confirmed by comparing with the updated model.
Tsuruta, Tadahiko; Sasao, Eiji
Oyo Chishitsu, 56(6), p.298 - 307, 2016/02
Japan Atomic Agency (JAEA) are performing Mizunami Underground Research Laboratory project (MIU project), which is a broad scientific study of the deep geological environment as a basis of research and development for geological disposal of nuclear wastes. Geological investigations, reflection seismic surveys, borehole drilling, etc., are carried out to understand the distribution and properties of important geological structures (permeable fractures, faults, etc). This report summarizes specifications and data characteristic of geological mapping on the shafts and gallery wall, and describes contributions to developments of geological model based on the results of geological mapping.
Kojima, Keiji*; Onishi, Yuzo*; Aoki, Kenji*; Tochiyama, Osamu*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Yoshida, Hidekazu*; Murakami, Hiroaki; Sasao, Eiji
JAEA-Research 2015-017, 54 Pages, 2015/12
JAEA-Research-2015-017.pdf:17.3MB
This report is concerned with research to reconstruct more realistic near-field (NF) concept for the geological disposal of radioactive waste. This year is the final year of this committee activities. So we have carried out the summary on Re-thinking of NF concept and its technical basis. Cooperation between the study fields and combination of various science and technology and evaluation methods are one of the important technical bases of NF concept. In addition, since the "Great East Japan Earthquake 2011", the safety paradigm has shifted dramatically. In the reconstruction of realistic NF concept, it is necessary to analyze what security matters whether society has become unacceptable for geological disposal. Committee, we also exchange views on such matters and presented the direction of future research and development for geological disposal.
