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Nara, Yoshitaka*; Kato, Masaji*; Sato, Tsutomu*; Kono, Masanori*; Sato, Toshinori
Journal of MMIJ, 138(4), p.44 - 50, 2022/04
It is important to understand the long-term migration of radionuclides when considering rock engineering projects such as the geological disposal of radioactive waste. The network of fractures and pores in a rock mass plays a major role in fluid migration as it provides a pathway for fluid flow. The geometry of a network can change due to fracture sealing by some fine-grained materials over long-term periods. In the present study, we use a macro-fractured granite sample to investigate the change of permeability that occurs under the flow of water that includes two different amounts of clay. Findings showed that clay accumulated in a fracture and that the permeability (hydraulic conductivity) of the granite sample decreased over time, which was greater in for the higher clay content. We concluded that the accumulation of clay minerals in the fracture decreased the permeability of the rock. Furthermore, we consider that the filling and closure of fractures in rock is possible under the flow of groundwater that includes clay minerals.
Shimada, Koji; Sueoka, Shigeru
Fisshion, Torakku Nyusureta, (33), p.19 - 21, 2020/10
no abstracts in English
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：5 Percentile：32.38(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.
Sakai, Toshihiro
JAEA-Data/Code 2018-006, 75 Pages, 2018/07
JAEA-Data-Code-2018-006.pdf:2.9MB
JAEA-Data-Code-2018-006-appendix(CD-ROM).zip:0.87MB
Data of bulk chemical compositions (major elements and trace elements) and/or of modal compositions of the Toki granitic body are compiled as a data-base for the purpose of improving geological and petrological basic information of the Mizunami Underground Research Laboratory Project and the Regional Hydrogeological Study Project. 696 rock samples are collected from the outcrops and boreholes of the Regional Hydrogeological Study Project, and 636 rock samples are collected from the Mizunami Underground Research Laboratory Construction Site. The analysis data of rock samples, as granitic rock samples, intrusive rock samples and crack filling samples, are attached three-dimensional position information to each thesis and report.
Ino, Kohei*; Hernsdorf, A. W.*; Konno, Yuta*; Kozuka, Mariko*; Yanagawa, Katsunori*; Kato, Shingo*; Sunamura, Michinari*; Hirota, Akinari*; Togo, Yoko*; Ito, Kazumasa*; et al.
ISME Journal, 12(1), p.31 - 47, 2018/01
Times Cited Count：49 Percentile：91.33(Ecology)In this study, we found the dominance ofanaerobic methane-oxidizing archaea in groundwater enriched in sulfate and methane from a 300-m deep underground borehole in granitic rock.
setting approaches for rocks for the performance assessment of geological disposal; Application for granitic rocksTachi, Yukio; Suyama, Tadahiro*; Shibutani, Sanae*
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 24(2), p.109 - 133, 2017/12
For performance assessment (PA), the distribution coefficient (K) need to be determined taking into account the specific PA conditions, including geochemical variability or uncertainty. The K setting approach for rocks was developed by integrating three methods; (i) direct use of measured K data extracted from the sorption database, (ii) semi-quantitative estimation by scaling differences between experimental and PA conditions, and (iii) thermodynamic sorption models. This approach was tested for granitic rock by comparing K values and their uncertainties of Cs and Am. The results indicated that K can be quantitatively evaluated by all approaches when adequate data and models are available. The K dataset for safety-relevant 25 radionuclides was developed based on the direct use of measured data, and compared with the recent K dataset in European PA projects. This K setting approaches allowed to estimate the K values and their uncertainties under the expected site conditions.
Ino, Kohei*; Konno, Yuta*; Kozuka, Mariko*; Hirota, Akinari*; Togo, Yoko*; Fukuda, Akari*; Komatsu, Daisuke*; Tsunogai, Urumu*; Tanabe, Akifumi*; Yamamoto, Satoshi*; et al.
Environmental Microbiology Reports (Internet), 8(2), p.285 - 294, 2016/04
Times Cited Count：26 Percentile：68.59(Environmental Sciences)To understand the subsurface biosphere, borehole investigation was conducted for 300-m deep granitic rocks at the Mizunami underground research laboratory, Japan. The initial biomass was the highest with the flourish of aerobic H
-oxidizing Hydrogenophaga spp., whereas an uncultivated lineage of the phylum Nitrospirae became predominant after three years with decreasing biomass. The common occurrence of many species of Nitrospirae and Chlorobi phyla at the geographically distinct sites and the exclusive detection of their phylogenetically related environmental sequences from deep groundwaters and terrestrial hot springs, suggest that these bacteria are indigenous and potentially adapted to the deep terrestrial subsurface.
Construction Department; Tono Geoscience Center, Sector of Decommissioning and Radioactive Waste Management; Horonobe Underground Research Center, Sector of Decommissioning and Radioactive Waste Management
JAEA-Technology 2015-034, 411 Pages, 2016/03
JAEA-Technology-2015-034.pdf:103.07MB
This report presents the results of shaft and gallery excavation performed focusing on crystalline rock (Mizunami) and sedimentary rock (Horonobe) from the point of view of construction technologies applied and the information obtained at respective construction stages, which is required for construction designing Facility construction in general, its goal is to build the facilities and the general and accrual designs are made based on the specific construction plan, while the construction of shafts and research galleries is being conducted based on the research plan. This construction is performed in the deep underground where significant uncertainties exit, for instance, it is difficult to obtain the precision information from preliminary investigation, construction work is inextricability liked to the stepwise research, and this very long-term construction period is likely to be receiving restrictions concerning environmental and social interests. Therefore, there are a number of conditions can not to be predicted at the initial design stage. Timely and appropriate actions will be taken to deal with these particular conditions, such as changing on design due to the revision of the research and construction plan while conducting excavation construction. In the series of construction activities: from input (i.e. construction conditions) to completion of the construction under the particular conditions, we summarize the experiences obtained at respective construction stages as the important information to transfer the technology to the similar construction in the future. This report describes the general consideration and summary of chapters at the beginning, and introduces the construction activities performed at each rock series.
Suzuki, Yohei*; Mukai, Hiroki*; Ishimura, Toyoho*; Yokoyama, Takatomi*; Sakata, Shuhei*; Hirata, Takafumi*; Iwatsuki, Teruki; Mizuno, Takashi
Scientific Reports (Internet), 6, p.22701_1 - 22701_6, 2016/03
Times Cited Count：14 Percentile：49.58(Multidisciplinary Sciences)The stimulation of bacterial activities that convert hexavalent uranium to tetravalent uranium appears to be feasible for cost-effective remediation of contaminated aquifers. However, U(VI) reduction typically results in the precipitation of U(IV) particles less than 5 nanometers in diameter. Here we show that U(IV) nanoparticles of coffinite formed in fracture-filling calcium carbonate in a granitic aquifer. As the microbiologically induced precipitation of calcium carbonate in aquifer systems worldwide is extremely common, we anticipate simultaneous stimulation of microbial activities for precipitation reactions of calcium carbonate and U(IV) nanoparticles, which leads to long-term sequestration of uranium and other radionuclides in contaminated aquifers and deep geological repositories.
Koike, Katsuaki*; Kubo, Taiki*; Liu, C.*; Masoud, A.*; Amano, Kenji; Kurihara, Arata*; Matsuoka, Toshiyuki; Lanyon, B.*
Tectonophysics, 660, p.1 - 16, 2015/10
Times Cited Count：26 Percentile：65.77(Geochemistry & Geophysics)This study integrates 3D models of rock fractures from different sources and hydraulic properties aimed at identifying relationships between fractures and permeability. A geostatistical method (GEOFRAC) that can incorporate orientations of sampled data was applied to 50,900 borehole fractures for spatial modeling of fractures over a 12 km by 8 km area, to a depth of 1.5 km. GEOFRAC produced a plausible 3D fracture model, in that the orientations of simulated fractures correspond to those of the sample data and the continuous fractures appeared near a known fault. Small-scale fracture distributions with dominant orientations were also characterized around the two shafts using fracture data from the shaft walls. By integrating the 3D model of hydraulic conductivity using sequential Gaussian simulation with the GEOFRAC fractures from the borehole data, the fracture sizes and directions that strongly affect permeable features were identified.
Suzuki, Yohei*; Konno, Yuta*; Fukuda, Akari*; Komatsu, Daisuke*; Hirota, Akinari*; Watanabe, Katsuaki*; Togo, Yoko*; Morikawa, Noritoshi*; Hagiwara, Hiroki; Aosai, Daisuke*; et al.
PLOS ONE (Internet), 9(12), p.e113063_1 - e113063_20, 2014/12
Times Cited Count：12 Percentile：34.33(Multidisciplinary Sciences)We present multi-isotopic evidence of microbially mediated sulfate reduction in a granitic aquifer, a representative of the terrestrial crust habitat. Deep groundwater of meteoric origin was collected from underground boreholes drilled into the Cretaceous Toki granite, central Japan. A large sulfur isotopic fractionation of 20-60 permil diagnostic to microbial sulfate reduction is associated with the investigated groundwater containing sulfate below 0.2 mM. In contrast, a small carbon isotopic fractionation (
30 permil) is not indicative of methanogenesis. Our results demonstrate that the deep biosphere in the terrestrial crust is metabolically active and playing a crucial role in the formation of reducing groundwater even under low energy fluxes.
Yamaguchi, Tetsuji; Nakayama, Shinichi; Okamoto, Hisato
Radiochimica Acta, 90(12), p.863 - 868, 2003/01
Times Cited Count：4 Percentile：29.25(Chemistry, Inorganic & Nuclear)no abstracts in English
Yamaguchi, Tetsuji
Kyouto Daigaku Daigakuin Kougaku Kenkyuka Hakase Gakui Ronbun, 136 Pages, 2001/01
no abstracts in English
Sakamoto, Yoshiaki; Nagao, Seiya; Ogawa, Hiromichi; Rao, R. R.*
Radiochimica Acta, 88(9-11), p.651 - 656, 2000/09
Times Cited Count：11 Percentile：59.85(Chemistry, Inorganic & Nuclear)no abstracts in English
*; *
JNC TJ7440 2000-005, 45 Pages, 2000/03
JNC-TJ7440-2000-005.pdf:2.72MB
no abstracts in English
*; *
JNC TJ1400 2000-008, 82 Pages, 2000/03
JNC-TJ1400-2000-008.pdf:3.05MB
no abstracts in English
Horita, M.*; *; Okutsu, Kazuo*; Yamamoto, Takuya*; Amemiya, Kiyoshi*
JNC TJ8400 2000-022, 303 Pages, 2000/02
JNC-TJ8400-2000-022.pdf:10.42MB
This report gives supplementary information and discussions on issues of the high-level waste geological disposal study. The following subjects are discussed ; (1)Evaluation of the effects of coefficient of lateral pressure to the specifications of disposal facilities (2)Functional development of remote operational machinery (3)Arrangement of basic data on cost estimation for disposal (4)Understanding of engineering countermeasures to potential phenomena deep under the ground (5)Selection of construction technologies (6)Establishment of the disposal concept under the coasts. For the coefficient of lateral pressure equal to 2, the cross section of disposal drift, the disposal drift spacing, the waste package pitch in the disposal drift and the specification of supporting system are designed. They are compared with those for the case of coefficient of lateral pressure equal to 1. In the case of coefficient of lateral pressure equal to 2, total length of drifts is 1.5 times, and total excavation volume is 1.8 times larger than later case. For the sealing, transportation and emplacement equipment for waste, technology of the fundamental function, remote operation, accidental events and countermeasures are discussed. The plan for developments on those items is proposed. The item of the cost for the construction, operation, and backfilling are discussed. The surface facilities, and, worker arrangement plan are proposed. For the potential phenomena encountered deep under the ground, the countermeasures are investigated form the construction experience, and the future research subjects are discussed for the underground research laboratory. For the construction technologies, the experience of construction management for the tunnel is investigated, and, the research subjects are proposed. For the disposal concept under coasts, rock condition, design condition, construction management, and quality control are compared with the disposal concept under the ground. The ...
Yamaguchi, Tetsuji
Genankyo Dayori, (173), p.11 - 14, 2000/01
no abstracts in English
Toyama, Shigeyuki*; Wakamatsu, Hisanori; Okazaki, Hikoya
JNC TJ7440 99-031, 22 Pages, 1999/09
no abstracts in English
