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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

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.

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.

Journal Articles

Development of evaluation method for variability of groundwater flow conditions associated with long-term topographic change and climate perturbations

Onoe, Hironori; Kosaka, Hiroshi*; Matsuoka, Toshiyuki; Komatsu, Tetsuya; Takeuchi, Ryuji; Iwatsuki, Teruki; Yasue, Kenichi

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 26(1), p.3 - 14, 2019/06

In this study, it is focused on topographic changes due to uplift and denudation, also climate perturbations, a method which is able to assess the long-term variability of groundwater flow conditions using the coefficient variation based on some steady-state groundwater flow simulation results was developed. Spatial distribution of long residence time area which is not much influenced due to long-term topographic change and recharge rate change during the past one million years was able to estimate through the case study of the Tono area, Central Japan. By applying this evaluation method, it is possible to identify the local area that has low variability of groundwater flow conditions due to topographic changes and climate perturbations from the regional area quantitatively and spatially.

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

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:62.87(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.

Journal Articles

Chapter 8, Research and development on geological disposal technology as a field of practice in integrated physical geography

Komatsu, Tetsuya

Jissen Togo Shizen Chirigaku, p.105 - 121, 2018/07

no abstracts in English

Journal Articles

Characteristics of electron spin resonance signal of quartz from sediments and adjacent bedrocks

Tokuyasu, Kayoko; Yasue, Kenichi; Komatsu, Tetsuya; Tamura, Itoko; Horiuchi, Yasuharu

QST-M-2; QST Takasaki Annual Report 2015, P. 189, 2017/03

Understanding the stage of mountain building is crucial to the stability assessment of geological environments in geological disposal system. In this context, we have carried out the research and development of provenance analysis techniques to elucidate the mountain-building stage. Here we present the results focusing on the R&D using the Electron Spin Resonance (ESR) signals from quartz in sediments and their basement rocks.

Journal Articles

Cenozoic tectonic evolution of the Pamir; A Review

Komatsu, Tetsuya

Chigaku Zasshi, 125(5), p.661 - 698, 2016/10

The Pamir is a mountain region of the westernmost part of the Himalayan-Tibetan orogen and extends $$sim$$300 km from north to south and 300-400 km from west to east. The Pamir lies on a double subduction zone, where two buoyant continental lithospheric plates have subducted several hundred kilometers deep into the asthenosphere. The southern plate is the northward-dipping Hindu Kush slab, and the northern plate is the southward-dipping Pamir slab. This paper reviews recent studies on the Cenozoic tectonic evolution of the Pamir in this unique tectonic setting.

Oral presentation

The Fragmentation and alteration history of fault rocks in the Byobuyama fault, Gifu prefecture, central Japan

Katori, Takuma*; Kobayashi, Kenta*; Yasue, Kenichi; Niwa, Masakazu; Komatsu, Tetsuya; Hosoya, Takushi*; Sasao, Eiji

no journal, , 

Understanding fault zone evolution is important for constructing the topographical and geological model for a time scale more than one million year. We analyzed fault rocks of the Byobuyama fault in Tono area by several methods including structural analysis in the field and using optical microscope, determination of mineral composition based on X-ray diffraction analysis, and chemical composition analysis using an X-ray fluorescence instrument. Based on these analyses, studied fault rocks could record several stages of fault activity under different depths and stress regimes.

Oral presentation

Provenance analysis techniques for understanding the stage of mountain buildings; Approaches focusing on the radiation damage of quartz

Yasue, Kenichi; Komatsu, Tetsuya; Tokuyasu, Kayoko; Tamura, Itoko; Horiuchi, Yasuharu

no journal, , 

no abstracts in English

Oral presentation

Radiometric ages and petrographic properties of the Oroshi volcanic ash in the lower Tokai Group

Hoshi, Hiroyuki*; Tamura, Itoko; Komatsu, Tetsuya

no journal, , 

no abstracts in English

Oral presentation

Oral presentation

Geosphere stability project; Study on provenance analysis techniques

Yasue, Kenichi; Sugai, Toshihiko*; Tokuyasu, Kayoko; Komatsu, Tetsuya; Horiuchi, Yasuharu; Shimizu, Hitoshi*; Morita, Yasuhiko*

no journal, , 

no abstracts in English

Oral presentation

Geosphere stability project, 2; Development of geological-evolutionary model in the Horonobe area

Matsuoka, Toshiyuki; Komatsu, Tetsuya; Yasue, Kenichi; Onoe, Hironori; Oyama, Takuya; Iwatsuki, Teruki; Sasao, Eiji; Umeda, Koji

no journal, , 

This paper summarized the current status of R&D activities with development of geological-evolutionary model in the Horonobe area, northern Hokkaido. This study has been carried out in the area of approx. 100 km $$times$$ 30 km. Two stages, approx. 1 Ma and 0.33 Ma were selected for paleo-geological modeling based on geological history of several millions of years in and around the study area. 3D steady-state groundwater flow simulations and sensitivity analysis using these models were carried out. Long-term evolution of groundwater flow conditions caused by long-term geological phenomena was assessed using statistical analysis. From the results, the spatial distribution of long-term stability of groundwater flow conditions were estimated and important factors for assessment of long-term evolution of groundwater flow conditions were extracted. In addition, the results of groundwater flow simulation were analyzed from the viewpoint of geochemical environment within the groundwater.

Oral presentation

Geosphere stability project, 1; Development of geological-evolutionary model in the Tono area

Onoe, Hironori; Komatsu, Tetsuya; Yasue, Kenichi; Iwatsuki, Teruki; Takeuchi, Ryuji; Kato, Tomoko; Sasao, Eiji; Umeda, Koji

no journal, , 

This paper summarized the current status of R&D activities with development of geological-evolutionary model in the Tono area, Central Hokkaido. This study has been carried out in the area of approx. 20 km square. Four stages, approx. 3Ma, 1Ma, 0.45Ma and 0.14Ma were selected for paleo-geological modeling based on geological history of several millions of years in and around the study area. 3D steady-state groundwater flow simulations and sensitivity analysis using these models were carried out. Long-term evolution of groundwater flow conditions caused by long-term geological phenomena was assessed using statistical analysis. From the results, the spatial distribution of long-term stability of groundwater flow conditions were estimated and important factors for assessment of long-term evolution of groundwater flow conditions were extracted. In addition, the results of groundwater flow simulation were analyzed from the viewpoint of geochemical environment within the groundwater.

Oral presentation

Geosphere stability project, 3; Provenance analysis techniques

Tokuyasu, Kayoko; Yasue, Kenichi; Komatsu, Tetsuya; Tamura, Itoko; Horiuchi, Yasuharu

no journal, , 

We have carried out the research and development of provenance analysis techniques to elucidate the mountain-building stage using quartz ESR signals in sediments. The R&D was conducted using the Tokai Formation including Toki Sand and Gravel Formation distributed over the Tono area. In the northern part of the area, bedrocks consist of sedimentary rocks, Nohi Rhyolite and Sanyo Granite, whereas consist of Ryoke Granites in the southern part. Samples of sediments were taken from the quarry located between the Tsukechi River and Atera fault. Basement rock samples were also taken in and around the quarry. Outcrop observation indicates that the provenance of sediments changed between the lower and upper parts. Quartz grains for ESR measurements were extracted from all samples. As a result, granitic rocks of Sanyo belt were not exposed to the drainage basin during the deposition of the lower part between 3.9 and 2.0 Ma, then the granitic rocks were exposed during the deposition of upper part after about 2.0 Ma. We conclude that it is possible to estimate the sediment provenance using ESR properties.

Oral presentation

OSL dating and tephra analysis of fluvial terrace sediments

Tokuyasu, Kayoko; Tamura, Itoko; Komatsu, Tetsuya; Yasue, Kenichi

no journal, , 

The uplift rate during the past hundred thousand years is estimated from the elevation and emergence ages of terrace surfaces which are used as geomorphologic standard. OSL dating is effective method to determine the emergence ages. Here we report a case study of quartz OSL dating of fluvial terrace sediments, and its adequacy is considered in the correlation with intercalated marker tephra. All samples were collected from fluvial terrace sediments along Kiso River and Tsukechi River which is a tributary of the Kiso. The investigated fluvial terrace sediments are composed of laminated sand layer and pumice layer which is likely to be reworked. The pumice was identified as On-Pm1 tephra by mineral composition, refractive indices of volcanic glass and phenocryst minerals, and the major element composition of volcanic glass. This indicated that the fluvial terrace sediments were deposited after 100ka. The extracted quartz grains from terrace sediments were measured by conventional SAR protocol. The obtained OSL ages are about 40-50 ka, being underestimated because the OSL decay curves from all samples were dominant by medium component which is unsuitable for OSL dating. We thus attempt to determine the equivalent dose using the isolated fast component OSL signal which is suitable for OSL dating.

Oral presentation

Study of fault evolution based on texture and chemical analyses of fault gouge; Case study of the Byobuyama fault, Gifu prefecture, central Japan

Katori, Takuma*; Kobayashi, Kenta*; Niwa, Masakazu; Shimizu, Mayuko; Komatsu, Tetsuya; Yasue, Kenichi; Horiuchi, Yasuharu

no journal, , 

We performed structural analyses and XRD, XGT and EPMA analyses of fault rocks of the Byobuyama fault to reconstruct the history of the fault activity at shallow depth, as a case study for improving research technique to reveal the history of active faults. The results show that fault gouge zone along the fault has experienced activities of several stages under different stress, and significant differences in the deformation and alteration mechanism exist between these stages. Especially, the flow deformation of the fault gouge indicates that a large amount of fluid was present during the deformation. Abundance of illite infers that such fault gouge was formed by relatively high temperature fluid. In addition, eluviation structure of albite may indicate a deformation under environment such as to promote reaction solution. In this presentation, we discuss the vicissitudes of deformation and alteration mechanism in the fault gouge along the Byobuyama fault.

51 (Records 1-20 displayed on this page)