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Journal Articles

Present status of the JAEA-AMS-TONO (2022FY)

Fujita, Natsuko; Miyake, Masayasu; Matsubara, Akihiro*; Ishii, Masahiro*; Watanabe, Takahiro; Jinno, Satoshi; Nishio, Tomohiro*; Ogawa, Yumi; Kimura, Kenji; Shimada, Akiomi; et al.

Dai-35-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.17 - 19, 2024/03

The JAEA-AMS-TONO facility at the Tono Geoscience Center, JAEA has three accelerator mass spectrometers. We report the present status of the JAEA-AMS-TONO.

JAEA Reports

Stable hydrogen and oxygen isotope analyses of geological samples using a thermal conversion elemental analyzer-isotope ratio mass spectrometer at Tono Geoscience Center

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

JAEA-Testing 2023-003, 67 Pages, 2024/02

JAEA-Testing-2023-003.pdf:4.63MB

A long-term geosphere stability for geological disposal is evaluated by the past geological environmental changes and modern conditions. Stable hydrogen and oxygen isotope ratios ($$delta$$D, $$delta$$$$^{18}$$O) of geological samples are useful information to estimate the past environmental changes and modern conditions. Recently, the thermal conversion elemental analyzer and isotope ratio mass spectrometer (TC-EA/IRMS) were installed in the Tono Geoscience Center for $$delta$$D and $$delta$$$$^{18}$$O measurements of geological samples. In this study, we reported analytical methods of $$delta$$D and $$delta$$$$^{18}$$O using international standard reference materials. In addition, evaluation tests of uncertainty by repeated analyses of the standards were performed using the TC-EA/IRMS. Furthermore, the $$delta$$D and $$delta$$$$^{18}$$O analyses by the TC- EA/IRMS were also applied to fault rock samples.

Journal Articles

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

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.

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2023)

Niwa, Masakazu; Shimada, Koji; Sueoka, Shigeru; Fujita, Natsuko; Yokoyama, Tatsunori; Ogita, Yasuhiro; Fukuda, Shoma; Nakajima, Toru; Kagami, Saya; Ogata, Manabu; et al.

JAEA-Review 2023-017, 27 Pages, 2023/10

JAEA-Review-2023-017.pdf:0.94MB

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 2023. The objectives and contents in fiscal year 2023 are described in detail based on the JAEA 4th Medium- and Long-term Plan (fiscal years 2022-2028). 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.

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2022

Niwa, Masakazu; Shimada, Koji; Sueoka, Shigeru; Ishihara, Takanori; Ogawa, Hiroki; Hakoiwa, Hiroaki; Watanabe, Tsuyoshi; Nishiyama, Nariaki; Yokoyama, Tatsunori; Ogata, Manabu; et al.

JAEA-Research 2023-005, 78 Pages, 2023/10

JAEA-Research-2023-005.pdf:6.51MB

This annual report documents the progress of research and development (R&D) in the 1st fiscal year of the Japan Atomic Energy Agency 4th Medium- and Long-term Plan (fiscal years 2022-2028) to provide the scientific base for assessing geosphere stability for long-term isolation of high-level radioactive waste. 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. The current status of R&D activities with previous scientific and technological progress is summarized.

Journal Articles

Development of an iron(II) complex exhibiting thermal- and photoinduced double proton-transfer-coupled spin transition in a short hydrogen bond

Nakanishi, Takumi*; Hori, Yuta*; Shigeta, Yasuteru*; Sato, Hiroyasu*; Kiyanagi, Ryoji; Munakata, Koji*; Ohara, Takashi; Okazawa, Atsushi*; Shimada, Rintaro*; Sakamoto, Akira*; et al.

Journal of the American Chemical Society, 145(35), p.19177 - 19181, 2023/08

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2022)

Sasao, Eiji; Ishimaru, Tsuneari; Niwa, Masakazu; Shimada, Akiomi; Shimada, Koji; Watanabe, Takahiro; Sueoka, Shigeru; Yokoyama, Tatsunori; Fujita, Natsuko; Ogita, Yasuhiro; et al.

JAEA-Review 2022-022, 29 Pages, 2022/09

JAEA-Review-2022-022.pdf:0.97MB

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 2022. The objectives and contents in fiscal year 2022 are described in detail based on the JAEA 4th Medium- and Long-term Plan (fiscal years 2022-2028). 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

JAEA Reports

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$$_{4}$$) seepage to the surface in the early stage of hydrocarbon exploration has attracted increasing attention. Also, detection of CH$$_{4}$$-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$$_{4}$$. 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 ($$sim$$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$$_{4}$$-bearing hot springs (Kawayu and Yunomine). The measurement near the hot springs detected a clear CH$$_{4}$$ anomaly ($$>$$2 ppm) that exceeded the background concentration. The estimation of CH$$_{4}$$ 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$$_{4}$$-bearing fluid emissions at the surface. Additionally, directions for use of the analyzer were summarized in this report.

Journal Articles

Newly found fault outcrops of the Tsuruga fault in the Mihama Town, Fukui Prefecture, Japan

Tateishi, Ryo*; Shimada, Koji; Iwamori, Akiyuki*; Wada, Shinya*; Seno, Shotaro*; Nagata, Ken*

Chishitsugaku Zasshi (Internet), 128(1), p.63 - 64, 2022/04

The Tsuruga Fault is an active right-lateral strike-slip fault that is about 20 km in length and distributed in the northeast-southwest direction from the eastern part of Tsuruga City to the southern part of Mihama Town, Fukui Prefecture. The Tsuruga fault borders the Jurassic accretionary complex (mixed rock) and the late Cretaceous granite around the Oritodani area in the Shinjo district of Mihama-cho. Lateral bendings of valleys along the fault in this area are clear geomorphological signatures of fault activity. We briefly report newly found multiple fault outcrops at these bending points with photos of them. This research is the result of joint research by Kansai Electric Power Company, University of Toyama, and JAEA.

Journal Articles

${it In situ}$ TEM observation and MD simulation of frank partial dislocation climbing in Al-Cu alloy

Chen, J.*; Yoshida, Kenta*; Suzudo, Tomoaki; Shimada, Yusuke*; Inoue, Koji*; Konno, Toyohiko*; Nagai, Yasuyoshi*

Materials Transactions, 63(4), p.468 - 474, 2022/04

 Times Cited Count:1 Percentile:18.71(Materials Science, Multidisciplinary)

In situ electron irradiation using high-resolution transmission electron microscopy (HRTEM) was performed to visualize the Frank loop evolution in aluminium-copper (Al-Cu) alloy with an atomic-scale spatial resolution of 0.12 nm. The ${it in situ}$ HRTEM observation along the [110] direction of the FCC-Al lattice, Frank partial dislocation bounding an intrinsic stacking fault exhibited an asymmetrical climb along the $$<$$112$$>$$ direction opposed to those in the reference pure Al under an electron irradiation, with a corresponding displacement-per-atom rate of 0.055-0.120 dpa/s. The asymmetrical climb of the partial dislocation was described as pinning effects due to Cu-Cu bonding in Guinier-Preston zones by a molecular dynamics simulation.

JAEA Reports

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.

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2020

Ishimaru, Tsuneari; Ogata, Nobuhisa; Kokubu, Yoko; Shimada, Koji; Niwa, Masakazu; Shimada, Akiomi; Watanabe, Takahiro; Sueoka, Shigeru; Yokoyama, Tatsunori; Fujita, Natsuko; et al.

JAEA-Research 2021-007, 65 Pages, 2021/10

JAEA-Research-2021-007.pdf:4.21MB

This annual report documents the progress of research and development (R&D) in the 6th 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.

Journal Articles

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

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.

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2021)

Ishimaru, Tsuneari; Kokubu, Yoko; Shimada, Koji; Shimada, Akiomi; Niwa, Masakazu; Watanabe, Takahiro; Sueoka, Shigeru; Yokoyama, Tatsunori; Fujita, Natsuko; Ogita, Yasuhiro; et al.

JAEA-Review 2021-012, 48 Pages, 2021/08

JAEA-Review-2021-012.pdf:1.64MB

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 2021. The objectives and contents in fiscal year 2021 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.

Journal Articles

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

AA2020-0092.pdf:4.61MB

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$$_{2}$$ 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.

Journal Articles

Characteristics of fault fracture zones of the activated Shionohira Fault and the non-activated Kuruma Fault of the 2011 Fukushima-ken Hamadori Earthquake, Northeast Japan

Aoki, Kazuhiro; Tanaka, Yukumo; Yoshida, Takumi; Shimada, Koji; Sakai, Toru*; Kametaka, Masao*; Seshimo, Kazuyoshi

Oyo Chishitsu, 62(2), p.64 - 81, 2021/06

Co-seismic surface ruptures in the Fukushima-ken Hamadori Earthquake of Mw 6.7 on April 11, 2011 exposed approximately 14 km trending NNW-SSE from Nameishi to northwest of Ishizumi Tsunaki of Tabito Town, Iwaki City and were newly named the Shionohira Fault. However, no surface ruptures appeared along an N-S trending active Kuruma fault extending 5 km south of the Shionohira Fault. Because of the proximity and similar strike, two locations in Shionohira Fault and one location in Kuruma fault were selected as the study area for the fault activity evaluation. The present study reports the results of a series of geological and drilling surveys, core observation, XRD, isotope, and fluid inclusion analyses, and water permeability test. The results obtained from the three locations offer a fundamental data base that can be utilized for fault activity evaluation by summarizing the geological, mineralogical, and fluid property characteristics of fault fracture zone.

Journal Articles

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

 Times Cited Count:30 Percentile:96.87(Astronomy & Astrophysics)

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 $$^{circ}$$C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 $$^{circ}$$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.

Journal Articles

Recent evolution of fission-track chronometry; Advanced analytical methods, understanding of annealing kinetics, and developments of new dating systems

Sueoka, Shigeru; Shimada, Koji; Hasebe, Noriko*; Tagami, Takahiro*

Radioisotopes, 70(3), p.189 - 207, 2021/03

no abstracts in English

Journal Articles

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

no abstracts in English

Journal Articles

Rapid identification of water-conducting fractures using a trace methane gas measurement

Niwa, Masakazu; Amano, Kenji; Takeuchi, Ryuji; Shimada, Koji

Groundwater Monitoring & Remediation, 41(3), p.41 - 50, 2021/00

 Times Cited Count:1 Percentile:8.75(Water Resources)

Identification of water-conducting fractures is important for the safety assessment of underground projects in crystalline rocks at geological disposal sites. We applied a portable methane gas analyzer by wavelength-scanned cavity ring-down spectroscopy to detect the water-conducting fractures in an underground tunnel excavated in granite with CH$$_{4}$$-rich groundwater. Two approaches were taken to obtain the profile of CH$$_{4}$$ concentration along the gallery walls: (1) Scan by walking at the speed of 0.5 m/s and (2) monitoring for 30 s at 0.5 or 1-m intervals. In the Scan by walking approach, the peaks of the CH$$_{4}$$ concentration corresponded well with the occurrence of high water flow rate fractures. Thus, this method is useful for rapid identification of major water-conducting fractures. Monitoring at constant intervals takes more time than the Scan by walking approach; however, this method can largely detect occurrences of fractures with low fluid fluxes.

222 (Records 1-20 displayed on this page)