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.

Quantitative analyses of major and trace elements in geological samples using a portable energy dispersive X-ray fluorescence spectrometer at Tono Geoscience Center; An Analytical method of whole-rock geochemical composition by 3-mm diameter small spot measurements

Yamamoto, Yusuke; Watanabe, Takahiro; Niwa, Masakazu; Shimada, Koji

JAEA-Testing 2021-003, 58 Pages, 2022/01

JAEA-Testing-2021-003.pdf:6.82MB

A long term geosphere stability for geological disposal is evaluated by the past geological environmental changes and modern conditions. Whole-rock geochemical compositions in rocks and sediments are useful information to estimate the past environmental changes and modern conditions. Recently, the portable X-ray fluorescence (XRF) were installed in the Tono Geoscience Center for rapid and simple whole-rock geochemical analyses (original specification; 8 mm-diameter analysis). In particular, the 3 mm-diameter small spot analysis using the portable XRF was performed for quantitative analyses of small-weight geological samples. In this study, we reported a quantitative method for major and trace elements using calibration curves by standard reference materials, as well as evaluation tests of uncertainty by repeated analyses of the standards measured by the portable XRF (3 mm-diameter small spot analysis). Furthermore, the small spot quantitative analyses by the portable XRF were also applied to fault rock samples that have been analyzed in previous studies.

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

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

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

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.

Discrimination between active and non-active faults based on the chemical composition of fault gouge; An Attempt using linear discriminant analysis

Tateishi, Ryo*; Shimada, Koji; Shimizu, Mayuko; Ueki, Tadamasa*; Niwa, Masakazu; Sueoka, Shigeru; Ishimaru, Tsuneari

Oyo Chishitsu, 62(2), p.104 - 112, 2021/06

https://doi.org/10.5110/jjseg.62.104

We attempted to discriminate between active and non-active faults by linear discriminant analysis using the chemical composition data of fault gouges in Japan, and then examined the elements that represent the difference between them and better discriminants. As a result, the multiple discriminants obtained could discriminate between them with high probability. In addition, the generalization performance of these discriminants is discussed, and the discriminants that can be expected to have high discriminant performance for unknown samples are presented. Also, from the combination of elements common to these discriminants, we narrowed down the number of elements that represent the difference between active and non-active faults to 6, and showed that the combination of TiO and Sr contributing the most to the discrimination. The method applied in this study is an innovative one that can discriminate the activity by chemical analysis of fault rocks that are universally present in the bedrock.

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

https://doi.org/10.1038/s41550-020-01271-2

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Dating of a fault zone distributed in the South Kyushu shear zone based on fission-track thermochronology and U-Pb dating

Sueoka, Shigeru; Shimada, Koji; Terusawa, Shuji*; Iwano, Hideki*; Danhara, Toru*; Ogita, Yasuhiro; Hirata, Takafumi*

Chishitsugaku Zasshi, 127(1), p.25 - 39, 2021/01

https://doi.org/10.5575/geosoc.2020.0052

no abstracts in English

Quantitative and semi-quantitative analyses using a portable energy dispersive X-ray fluorescence spectrometer; Geochemical applications in fault rocks, lake sediments, and event deposits

Watanabe, Takahiro; Ishii, Chikako; Ishizaka, Chika; Niwa, Masakazu; Shimada, Koji; Sawai, Yuki*; Tsuchiya, Noriyoshi*; Matsunaka, Tetsuya*; Ochiai, Shinya*; Nara, Fumiko*

Journal of Mineralogical and Petrological Sciences, 116(3), p.140 - 158, 2021/00

https://doi.org/10.2465/jmps.201224

A portable energy dispersive X-ray fluorescence spectrometer (potable XRF) can be an effective tool for detecting chemical elements in various materials, such as geological, and environmental samples. In this study, working curves were confirmed using reference materials, such as igneous rocks and other geochemical standards, distributed by national and international organizations. Subsequently, quantification and semi-quantification analyses were performed by the portable XRF for inorganic elements in (A) fault rocks, (B) lake sediments from the middle Japan, and (C) soils with paleotsunami deposits from the Pacific coast of northeast Japan. Twenty-four elements (Mg-U) in these geological samples were measured by potable XRF using our working curves. Measured values by the portable XRF of the samples were good agreement with the reported values in almost cases.

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.

Measurement time and result of apatite FT density using FT automatic measuring device

Shimada, Koji; Sueoka, Shigeru

Fisshion, Torakku Nyusureta, (33), p.19 - 21, 2020/10

no abstracts in English

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2020)

Ishimaru, Tsuneari; Ogata, Nobuhisa; Shimada, Koji; Kokubu, Yoko; Niwa, Masakazu; Asamori, Koichi; Watanabe, Takahiro; Sueoka, Shigeru; Komatsu, Tetsuya; Yokoyama, Tatsunori; et al.

JAEA-Review 2020-010, 46 Pages, 2020/07

JAEA-Review-2020-010.pdf:1.89MB

This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2020. The objectives and contents in fiscal year 2020 are described in detail based on the JAEA 3rd Medium- and Long-term Plan (fiscal years 2015-2021). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. The plan 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.