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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.

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

Provenance analysis using rapid quantification of heavy minerals via EPMA; A Case study in the Horonobe region, Hokkaido, northern Japan

Yonaga, Yusuke; Sano, Naomi*; Amamiya, Hiroki*; Ogita, Yasuhiro; Niwa, Masakazu; Yasue, Kenichi*

Oyo Chishitsu, 62(1), p.2 - 12, 2021/04

Provenance analysis based on quick identification of heavy minerals using an electron probe microanalyzer (EPMA) was applied to samples from Pleistocene sediments in Horonobe region, Hokkaido, where major provenance rocks can be sedimentary and mafic igneous rocks. The concentrations of 16 elements were measured in individual grains to identify the mineral species based on their chemical composition. In addition, microscopic observation of thin sections and gravel composition analysis were conducted to confirm the validity of the quick identification of heavy minerals. These analyses clarify that combinations of several heavy mineral species can be a useful index of provenance rocks from the Soya Hill and Teshio Mountains, and suggest that uplift of the Soya Hill after ca. 1.5 Ma constrained supply of sediments from the Teshio Mountains. On the other hand, minerals uncommon both in the Soya Hill and Teshio Mountains, such as hornblende, are included in the Pleistocene sediments. This suggests that a sediment supply from distant area was also significant, like transportation by the Teshio River. The method for quick identification of heavy minerals using EPMA can provide an information about provenance rocks difficult to identify only by gravel composition analysis.

JAEA Reports

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.

Journal Articles

Showcase of case studies on impacts of fault activities based on field investigations

Niwa, Masakazu

Fisshion, Torakku Nyusureta, (33), p.22 - 24, 2020/10

Understanding of an impact of fault activity to an underground rock mass is important for a safety assessment for geological disposal. This report introduced the geological survey on the Atotsugawa Fault, central Japan, to investigate spatial distribution and characteristics of fault zones.

Journal Articles

K-Ar ages of an andesitic parallel dike swarm in the Takane area, Takayama City, Gifu Prefecture, Central Japan

Niwa, Masakazu; Ueki, Tadamasa*; Hoshi, Hiroyuki*; Sugisaki, Yuichi*; Yagi, Koshi*; Tozawa, Terumasa

Chishitsugaku Zasshi, 126(9), p.543 - 548, 2020/09

A large number of paleomagnetic and chronological studies have contributed to the elucidation of the early Miocene clockwise rotation of Southwest Japan associated with the major opening of back-arc basins of the Japan Sea. Paleomagnetic data from an andesitic parallel dike swarm in the Takane area, Takayama City, Gifu Prefecture, Central Japan, were previously reported, showing the easterly deflection of the observed magnetization direction compared to an early Miocene expected paleomagnetic direction. This must represent the clockwise rotation during the opening of the Japan Sea, if the dike swarm was intruded before the opening event. Here, we report new K-Ar hornblende ages from an andesite dike of the dike swarm. These ages are statistically indistinguishable, indicating emplacement of the dike swarm before the clockwise rotation.

JAEA Reports

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.

JAEA Reports

Study on sample description, composition, and preparation for dating of altered volcanic rocks

Niwa, Masakazu; Ueki, Tadamasa*; Hoshi, Hiroyuki*; Sugisaki, Yuichi*

JAEA-Research 2020-003, 33 Pages, 2020/07

JAEA-Research-2020-003.pdf:5.69MB

Ages of volcanic rocks are helpful information to understand the impact of volcanism concerning a site characterization and a safety assessment for geological disposal. In this study, mineralogical and geochemical data of altered volcanic rocks were collected using a polarizing microscope, X-ray diffractometer, X-ray fluorescence spectrometer, X-ray analytical microscope, and electron probe microanalyzer, to select targets suitable for reliable K-Ar dating. In addition, sample preparation procedures such as freeze-thawing and HCl treatment were examined to concentrate unaltered plagioclase which is one of major phenocrysts in volcanic rocks. These data and procedures were compiled in this report.

Journal Articles

Zircon U-Pb and fission-track ages for tephra interbedded in Neogene and Quaternary in Horonobe area, northern Hokkaido

Niwa, Masakazu; Amamiya, Hiroki*; Yonaga, Yusuke; Ogita, Yasuhiro; Yasue, Kenichi*; Iwano, Hideki*; Danhara, Toru*; Hirata, Takafumi*

Chishitsugaku Zasshi, 126(5), p.267 - 283, 2020/05

U-Pb and fission-track (FT) ages from single zircon grain were measured for three tephra samples (TKB3, TKB6, and TKB7) intercalated in Neogene to Quaternary in Horonobe area, Hokkaido, to understand their depositional ages. In TKB3 and TKB6, weighed average U-Pb and FT ages for zircon grains within the youngest age range are coincident within a range of error 2 $$sigma$$ each other, which suggest that their ages correspond to the eruption ages. In TKB7, FT ages for most zircons are reset to their U-Pb ages or younger. The weighed average FT age for all analyzed zircons and weighed average U-Pb age for zircon grains within the youngest age range are coincident within a range of error 2 $$sigma$$ each other. Thus, their ages could also show the eruption age.

Journal Articles

Seismic subsidence near the source region of the 1662 Kanbun Hyuganada Sea earthquake; Geochemical, stratigraphical, chronological, and paleontological evidences in Miyazaki Plain, southwest Japan

Niwa, Masakazu; Kamataki, Takanobu*; Kurosawa, Hideki*; Kokubu, Yoko; Ikuta, Masafumi*

Island Arc, 29(1), p.e12341_1 - e12341_26, 2020/01

 Times Cited Count:0 Percentile:0(Geosciences, Multidisciplinary)

Based on detailed geochemical and paleontological analyses for lowland sediments in the Miyazaki Plain, southwest Japan, we clearly identified environmental change from the lower terrestrial sediments to the upper shallow marine sediments. Radiocarbon ages and tephra data suggest that the environmental change is attributed to local subsidence due to the 1662 Kanbun Hyuganada Sea Earthquake shown in historical records. This findings are important for historical earthquake studies because the study area is a part of the expected focal region of megathrust earthquakes along the Nankai Trough.

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2018

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

JAEA-Research 2019-006, 66 Pages, 2019/11

JAEA-Research-2019-006.pdf:4.39MB

This annual report documents the progress of research and development (R&D) in the 4th 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. In this report, the current status of R&D activities with previous scientific and technological progress is summarized.

Journal Articles

Identification of capable faults using fault rock geochemical signatures; A Case study from offset granitic bedrock on the Tsuruga Peninsula, central Japan

Niwa, Masakazu; Shimada, Koji; Ishimaru, Tsuneari; Tanaka, Yoshihiro*

Engineering Geology, 260, p.105235_1 - 105235_15, 2019/10

 Times Cited Count:3 Percentile:43.13(Engineering, Geological)

In order to identify specific chemical changes induced by recent, near-surface faulting, we compared two faults of different size and evolutionary history, the active Shiraki-Nyu Fault and a nearby minor, inactive fault in central Japan, in terms of their mineralogical and geochemical features. Our analyses suggest that (1) chemical changes such as depletion of Na$$_{2}$$O and CaO derived from smectite and illite formation, and that changes such as increase of U, Y and REEs derived from absorption to these clay minerals, occurred during the fault initiation and subsequent retrograde alteration and are identical in the two faults, and that (2) MnO increase accompanied by FeO depletion and a positive Ce anomaly can be a key to identify specific chemical changes due to recent, near-surface faulting, because this could be related to upward migration and oxidation of fault-driven reduced fluids from deep underground to the near-surface environment.

Journal Articles

Quantitative micro-X-ray fluorescence scanning spectroscopy of wet sediment based on the X-ray absorption and emission theories; Its application to freshwater lake sedimentary sequences

Katsuta, Nagayoshi*; Takano, Masao*; Sano, Naomi; Tani, Yukinori*; Ochiai, Shinya*; Naito, Sayuri*; Murakami, Takuma*; Niwa, Masakazu; Kawakami, Shinichi*

Sedimentology, 66(6), p.2490 - 2510, 2019/10

 Times Cited Count:2 Percentile:24.03(Geology)

Micro-X-ray fluorescence (XRF) scanning spectroscopy of marine and lake sedimentary sequences can provide detailed paleoenvironmental records available through element intensities proxy data. However, problems for effects of interstitial pore water on the micro-XRF intensities have been pointed out so far because of direct measurement on the split wet sediment surfaces. In this study, new methods for the XRF corrections were developed by being considered with the micro-X-ray scanning spectroscopy.

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2019)

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

JAEA-Review 2019-010, 46 Pages, 2019/09

JAEA-Review-2019-010.pdf:2.45MB

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, in fiscal year 2019. The objectives and contents in fiscal year 2019 are described in detail based on the outline of 7 years plan (fiscal years 2015-2021). Background of this research is clarified with the necessity and the significance for site investigation and safety assessment, and the past progress in this report. In addition, 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 2017

Ishimaru, Tsuneari; Ogata, Nobuhisa; Shimada, Akiomi; Asamori, Koichi; Kokubu, Yoko; Niwa, Masakazu; Watanabe, Takahiro; Saiga, Atsushi; Sueoka, Shigeru; Komatsu, Tetsuya; et al.

JAEA-Research 2018-015, 89 Pages, 2019/03

JAEA-Research-2018-015.pdf:14.43MB

This annual report documents the progress of research and development (R&D) in the 3rd 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. In this report, the current status of R&D activities with previous scientific and technological progress is summarized.

Journal Articles

Zircon U-Pb and Fission-track ages for the Ohta Tephra in the Pliocene Tokai Group, Central Japan

Ueki, Tadamasa; Niwa, Masakazu; Iwano, Hideki*; Danhara, Toru*; Hirata, Takafumi*

Chishitsugaku Zasshi, 125(3), p.227 - 236, 2019/03

no abstracts in English

Journal Articles

Provenance identification based on EPMA analyses of heavy minerals; Case study of the Toki Sand and Gravel Formation, central Japan

Shimizu, Mayuko; Sano, Naomi; Ueki, Tadamasa; Komatsu, Tetsuya; Yasue, Kenichi*; Niwa, Masakazu

Island Arc, 28(2), p.e12295_1 - e12295_13, 2019/03

 Times Cited Count:1 Percentile:12.62(Geosciences, Multidisciplinary)

no abstracts in English

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific Program for fiscal year 2018)

Ishimaru, Tsuneari; Ogata, Nobuhisa; Shimada, Akiomi; Asamori, Koichi; Kokubu, Yoko; Niwa, Masakazu; Watanabe, Takahiro; Saiga, Atsushi; Sueoka, Shigeru; Komatsu, Tetsuya; et al.

JAEA-Review 2018-020, 46 Pages, 2019/01

JAEA-Review-2018-020.pdf:1.25MB

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, in fiscal year 2018. The objectives and contents in fiscal year 2018 are described in detail based on the outline of 7 years plan (fiscal years 2015-2021). Background of this research is clarified with the necessity and the significance for site investigation and safety assessment, and the past progress in this report. In addition, 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 2016

Ishimaru, Tsuneari; Yasue, Kenichi*; Asamori, Koichi; Kokubu, Yoko; Niwa, Masakazu; Watanabe, Takahiro; Yokoyama, Tatsunori; Fujita, Natsuko; Saiga, Atsushi; Shimizu, Mayuko; et al.

JAEA-Research 2018-008, 83 Pages, 2018/12

JAEA-Research-2018-008.pdf:11.43MB

This annual report documents the progress of research and development (R&D) in the 2nd 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. In this paper, the current status of R&D activities with previous scientific and technological progress is summarized.

JAEA Reports

Petrographic data of silicic igneous rocks in the Tono area, central Japan

Ueki, Tadamasa; Niwa, Masakazu

JAEA-Data/Code 2018-005, 94 Pages, 2018/08

JAEA-Data-Code-2018-005.pdf:15.6MB

Mountain development has an influence on long-term changes of uplift, erosion, and groundwater flow related to change in hydraulic gradient. Provenance analysis is one of promising geological methods to understand origin and formation process of mountains. Case study in the Tono area, central Japan has been done for research and development of individual technique to estimate a provenance. In this report, petrological descriptions by meso- and microscopic observations and elemental distributions using scanning X-ray analytical microscope of basement rocks (silicic igneous rocks) from the study area were compiled.

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