Field-based description of near-surface crustal deformation in a high-strain shear zone; A Case study in southern Kyushu, Japan

Niwa, Masakazu; Shimada, Koji; Terusawa, Shuji*; Goto, Akira*; Nishiyama, Nariaki; Nakajima, Toru; Ishihara, Takanori; Hakoiwa, Hiroaki

Island Arc, 33(1), p.e12516_1 - e12516_16, 2024/02

https://doi.org/10.1111/iar.12516

To investigate the geological evidence of near-surface crustal deformations in a high-strain shear zone that has been geodetically identified but not associated with clear tectonic landforms, a fieldwork was conducted in E-W trending southern Kyushu high-strain shear zone, Japan. According to our study, an investigation based on the slip data from minor faults and the occurrences of fracture zones could help to identify a concealed fault that is small in terms of size to record tectonic landforms but can trigger large earthquakes.

Efficient detection of methane seepage using a vehicle-mounted cavity ring-down spectroscopy analyzer

Niwa, Masakazu; Shimo, Michito*; Shimada, Koji; Goto, Akira

JAEA-Research 2022-004, 38 Pages, 2022/06

JAEA-Research-2022-004.pdf:2.86MB
JAEA-Research-2022-004-appendix(CD-ROM).zip:0.41MB

Methane (CH) seepage to the surface in the early stage of hydrocarbon exploration has attracted increasing attention. Also, detection of CH-rich fluid emission can be applied to reconnaissance surveys for safety management in geological disposal of radioactive waste because high-temperature fluids that come from slab dehydration along a subduction zone are often rich in CH. These fluids likely migrate along faults and fractures. In this study, we employed a portable analyzer that used a wavelength-scanned cavity ring-down spectroscopy (CRDS) with high accuracy (in ppb levels) and short measurement intervals (1 s). An on-vehicle measurement that employed the CRDS system was performed in the Hongu area in southeast Kii Peninsula, Japan, which included CH-bearing hot springs (Kawayu and Yunomine). The measurement near the hot springs detected a clear CH anomaly (2 ppm) that exceeded the background concentration. The estimation of CH diffusion in air based on the Gaussian plume model corresponded to the result of the on-vehicle measurement. This study confirmed that the method using the vehicle-mounted CRDS analyzer can help in quickly and easily identifying CH-bearing fluid emissions at the surface. Additionally, directions for use of the analyzer were summarized in this report.

Infrared images of outcrops around the Kawayu hot springs, Hongucho, Tanabe City, Wakayama Prefecture

Shimada, Koji; Goto, Akira; Niwa, Masakazu; Shimo, Michito*

Chishitsugaku Zasshi, 127(10), p.I - II, 2021/10

AA2021-0095.pdf:1.35MB

https://doi.org/10.5575/geosoc.2021.0021

Continuous leaking point of high-temperature fluid (liquid/gas) from underground can be easily grasped by infrared images. We show images confirmed by a FLIR C5 camera that can simultaneously obtain an infrared image and a visible light image at the outcrops of Kawayu Onsen that naturally spring along the river. Outcrops and river surface temperature rise due to hot springs that leaking from riverbanks and riverbeds, rock temperature rise around cracks where gas containing high-concentration methane leaks with hot springs, abandoned fluid pathway due to construction of the bank and damming river for hot spring river bath in winter can be confirmed at a glance. Infrared images may be useful for quick identification of hot fluid leaking points from underground.

Methodology development and determination of solubility-limiting solid phases for a performance assessment of geological disposal of high-level radioactive and TRU wastes

Kitamura, Akira; Yoshida, Yasushi*; Goto, Takahiro*; Shibutani, Sanae*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 27(2), p.58 - 71, 2020/12

https://doi.org/10.3327/jnuce.27.2_58

Evaluation and estimation of solubility values are required for a performance assessment of geological disposal of high-level radioactive and TRU wastes. Selection of solubility-limiting solid phases (SSPs) that control the solubility of radionuclides is necessary for the evaluation and estimation of solubility values. The authors have developed a methodology for selection of the SSP through a calculation of saturation indices (SIs) using thermodynamic database to show a transparent procedure for the selection. Literature survey should be performed to confirm decision of the SSP from candidate SSPs which generally have larger SIs from realistic point of view for precipitation and solubility control. The authors have selected the SSPs for the elements of interest for the latest Japanese performance assessment in bentonite and cement porewaters after grouping various water compositions.

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2019

Ishimaru, Tsuneari; Ogata, Nobuhisa; Kokubu, Yoko; Shimada, Koji; Hanamuro, Takahiro; Shimada, Akiomi; Niwa, Masakazu; Asamori, Koichi; Watanabe, Takahiro; Sueoka, Shigeru; et al.

JAEA-Research 2020-011, 67 Pages, 2020/10

JAEA-Research-2020-011.pdf:3.87MB

This annual report documents the progress of research and development (R&D) in the 5th fiscal year during the JAEA 3rd Mid- and Long-term Plan (fiscal years 2015-2021) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planned framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques. The current status of R&D activities with previous scientific and technological progress is summarized.

Compilation of previous studies on secondary effects induced by earthquake and fault activity (Contract research)

Goto, Akira; Murakami, Masaki*; Sakai, Ryutaro*; Terusawa, Shuji*; Sueoka, Shigeru

JAEA-Review 2020-003, 60 Pages, 2020/03

JAEA-Review-2020-003.pdf:4.43MB

One of the natural phenomena that may affect the geological disposal system are earthquake and fault activity. Fault displacement due to the earthquake and fault activity will be considered the direct effects. In addition to it, it is necessary to consider the secondary effects include secondary faults formed by the seismic fault activity as well as spring water and mud volcanoes that are generated by fluid movement attributed to the fault activity. This paper introduces previous studies performed focused on the hydraulic effects (spring water and mud volcanoes) and mechanical effects (secondary faults) in order to understand the effects of these secondary phenomena on the geological disposal system. We were able to collect 142 literatures from Japan and overseas by searching for related keywords in Japanese and English. As a result, we compiled case studies of each secondary impact. From the viewpoint of geological disposal, we extracted the following issues for future research and development. As for the sump water induced by earthquakes and faulting, accumulation of information related to its mechanism, affected area, and activity history is required. As for the mud volcanoes, reviewing of the mechanism of anomalous pore water pressure that causing the formation, also development of estimation technique are required. And for the secondary faults, accumulation of the detailed spatial distribution and reviewing of formation mechanism are required.

Enhancement of the methodology of repository design and post-closure performance assessment for preliminary investigation stage, 3; Progress report on NUMO-JAEA collaborative research in FY2013 (Joint research)

Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Kitamura, Akira; Yoshikawa, Hideki; Oda, Chie; Ishidera, Takamitsu; et al.

JAEA-Research 2014-030, 457 Pages, 2015/03

JAEA-Research-2014-030.pdf:199.23MB

JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and post-closure performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, based on some examples of developing method of hydro-geological structure model, acquired knowledge are arranged using the tree diagram, and model uncertainty and its influence on the evaluation items were discussed. With regard to (2) study on scenario development, the developed approach for "defining conditions" has been reevaluated and improved from practical viewpoints. In addition, the uncertainty evaluation for the effect of use of cementitious material, as well as glass dissolution model, was conducted with analytical evaluation. With regard to (3) study on setting radionuclide migration parameters, based on survey of precedent procedures, multiple-approach for distribution coefficient of rocks was established, and the adequacy of the approach was confirmed though its application to sedimentary rock and granitic rock. Besides, an approach for solubility setting was developed including the procedure of selection of solubility limiting solid phase. The adequacy of the approach was confirmed though its application to key radionuclides.

Enhancement of the methodology of repository design and post-closure performance assessment for preliminary investigation stage, 2; Progress report on NUMO-JAEA collaborative research in FY2012 (Joint research)

Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Hayano, Akira; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.

JAEA-Research 2013-037, 455 Pages, 2013/12

JAEA-Research-2013-037.pdf:42.0MB

Following FY2011, JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, the tree diagram of methodology of groundwater travel time has been extended for crystalline rock, in addition, tree diagram for sedimentary rock newly has been organized. With regard to (2) study on scenario development, the existing approach has been improved in terms of a practical task, and applied and tested for near field focusing on the buffer. In addition, the uncertainty of some important processes and its impact on safety functions are discussed though analysis. With regard to (3) study on setting radionuclide migration parameters, the approaches for parameter setting have been developed for sorption for rocks and solubility, and applied and tested through parameter setting exercises for key radionuclides.

Data of heavy elements for light sources in EUV and XUV and for other applications

Koike, Fumihiro*; Funaba, Hisamichi*; Goto, Motoshi*; Kato, Daiji*; Kato, Takako*; Morita, Shigeru*; Murakami, Izumi*; Sakaue, Hiroyuki*; Sudo, Shigeru*; Suzuki, Chihiro*; et al.

AIP Conference Proceedings 1545, p.202 - 211, 2013/07

https://doi.org/10.1063/1.4815855

Atomic ionic states and transition properties of elements with atomic numbers Z ranging from 50 to 80 are discussed as these are important to the understanding of plasmas containing such heavy elements. As such, data productions and the current status of theoretical calculations in this field are discussed. Further, recent spectroscopic measurements and respective theoretical analyses for W, Gd, and Nd are provided.

New result in the production and decay of an isotope, 113 of the 113th element

Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sumita, Takayuki*; Wakabayashi, Yasuo*; Yoneda, Akira*; Tanaka, Kengo*; et al.

Journal of the Physical Society of Japan, 81(10), p.103201_1 - 103201_4, 2012/10

https://doi.org/10.1143/JPSJ.81.103201

An isotope of the 113th element, 113, was produced in a nuclear reaction with a Zn beam on a Bi target. We observed six consecutive decays following the implantation of a heavy particle in nearly the same position in the semiconductor detector, in extremely low background condition. The fifth and sixth decays are fully consistent with the sequential decays of Db and Lr both in decay energies and decay times. This indicates that the present decay chain consisted of 113, Rg (Z = 111), Mt (Z = 109), Bh (Z = 107), Db (Z = 105), and Lr (Z = 103) with firm connections. This result, together with previously reported results from 2004 and 2007, conclusively leads the unambiguous production and identification of the isotope 113, of the 113th element.