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Hiratsuka, Shinya; Asamori, Koichi; Saiga, Atsushi
JAEA-Research 2022-002, 38 Pages, 2022/06
JAEA-Research-2022-002.pdf:4.49MB
Deep groundwater originates from dehydration of Pacific and Philippine Sea slab subducting beneath Japanese islands, which has characteristics of high temperature and is rich in carbonate species. In this respect, it is very important for geological disposal of high-level radioactive waste to estimate reservoir and migration pathway of deep groundwater. The region where cracks are densely distributed can be regarded as the migration pathway of slab-derived fluid. It is highly probable that the region has strong anisotropy. Shear wave propagating through anisotropic media splits into two mutually orthogonally polarized waves due to shear wave polarization anisotropy. In this report, we applied shear wave splitting analysis to Hongu area of Tanabe City, Wakayama Prefecture and estimated the spatial distribution of leading shear wave polarization direction (LSPD) and arrival time difference between leading and lagging shear waves (dt). Based on comparison with helium isotope ratio of ground water and bubbling gas samples and two-dimensional resistivity structure estimated by previous study, we attempt to estimate migration pathway of slab-derived fluid in Hongu area of Tanabe City, Wakayama Prefecture. The main results are summarized as follows. When helium isotope ratio of groundwater and bubbling gas samples is high, dt value tends to be large. Shear wave propagating through high and low resistivity anomaly zone show small and large dt values, respectively. Previous study suggested that slab-derived fluid migrates from deeper part of western side of Hongu area and wells out in Yunomine and Kawayu hot springs. This is consistent with spatial distribution of dt values estimated by this study.
Nakayama, Masashi; Saiga, Atsushi
JAEA-Review 2020-042, 116 Pages, 2021/01
JAEA-Review-2020-042.pdf:10.33MB
The Horonobe Underground Research Laboratory Project will be conducted in three phases, namely "Phase 1: Surface-based investigations", "Phase 2: Construction Phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). This report summarizes the results of the investigations for the 2019 fiscal year (2019/2020). The investigations, which are composed of "Geoscientific research" and "R and D on geological disposal technology", were carried out according to "Horonobe Underground Research Laboratory Project Investigation Program for the 2019 fiscal year". The results of these investigations, along with the results which were obtained in other departments of Japan Atomic Energy Agency (JAEA), are properly offered to the implementations and the safety regulations. For the sake of this, JAEA has proceeded with the project in collaboration with experts from domestic and overseas research organizations.
Nakayama, Masashi; Saiga, Atsushi
JAEA-Review 2020-022, 34 Pages, 2020/11
JAEA-Review-2020-022.pdf:3.99MB
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies for geological disposal of High-level Radioactive Waste through investigations of the deep geological environment within the host sedimentary rock at Horonobe Town in Hokkaido, north Japan. The investigations will be conducted in three phases, namely "Phase 1: Surface-based investigations", "Phase 2: Construction phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). According to the research plan described in the 3rd Mid- and Long- term Plan of JAEA, "Demonstration of EBS in geological environment", "Demonstration of disposal concept", and "Validation of buffer capacity of the sedimentary rock to tectonism" are important issues of the Horonobe URL Project, and schedule of future research and backfill plans of the URL will be decided by the end of 2019 Fiscal Year. JAEA summarizes the research and development activities of the important issues carried out during the 3rd Mid- and Long-term Plan, and set out three important issues after 2020 fiscal year. After consultation with Hokkaido and Horonobe town, JAEA formulated the Horonobe underground research plan after 2020 fiscal year within the 3rd and 4th Mid- and Long-term Plan. This report summarizes the investigation program for the 2020 fiscal year (2020/2021).
Nakayama, Masashi; Saiga, Atsushi; Kimura, Shun; Mochizuki, Akihito; Aoyagi, Kazuhei; Ono, Hirokazu; Miyakawa, Kazuya; Takeda, Masaki; Hayano, Akira; Matsuoka, Toshiyuki; et al.
JAEA-Research 2019-013, 276 Pages, 2020/03
JAEA-Research-2019-013.pdf:18.72MB
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies for geological disposal of High-level Radioactive Waste through investigations of the deep geological environment within the host sedimentary rock at Horonobe Town in Hokkaido, north Japan. The investigations will be conducted in three phases, namely "Phase 1: Surface based investigations", "Phase 2: Construction phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). According to the research plan described in the 3rd Mid- and Long- term Plan of JAEA, "Near-field performance study", "Demonstration of repository design option", and "Verification of crustal-movement buffering capacity of sedimentary rocks" are important issues of the Horonobe URL Project, and schedule of future research and backfill plans of the project will be decided by the end of 2019 Fiscal Year. The present report summarizes the research and development activities of these 3 important issues carried out during 3rd Medium to Long-term Research Phase.
Saiga, Atsushi
JAEA-Review 2019-018, 122 Pages, 2020/01
JAEA-Review-2019-018.pdf:10.52MB
The Horonobe Underground Research Laboratory Project is planned to extend over a period 20 years. The investigations will be conducted in three phases, namely "Phase 1: Surface-based investigations", "Phase 2: Construction Phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). This report summarizes the results of the investigations for the 2018 fiscal year (2018/2019). The investigations, which are composed of "Geoscientific research" and "R&D on geological disposal technology", were carried out according to "Horonobe Underground Research Laboratory Project Investigation Program for the 2018 fiscal year". The results of these investigations, along with the results which were obtained in other departments of Japan Atomic Energy Agency (JAEA), are properly offered to the implementations and the safety regulations. For the sake of this, JAEA has proceeded with the project in collaboration with experts from domestic and overseas research organizations.
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.
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.
Hanamuro, Takahiro; Saiga, Atsushi
JAEA-Review 2018-027, 125 Pages, 2019/02
JAEA-Review-2018-027.pdf:21.79MB
The Horonobe Underground Research Laboratory Project is planned to extend over a period 20 years. The investigations will be conducted in three phases, namely "Phase 1: Surface-based investigations", "Phase 2: Construction Phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). This report summarizes the results of the investigations for the 2017 fiscal year (2017/2018). The investigations, which are composed of "Geoscientific research" and "R&D on geological disposal technology", were carried out according to "Horonobe Underground Research Laboratory Project Investigation Program for the 2017 fiscal year". The results of these investigations, along with the results which were obtained in other departments of Japan Atomic Energy Agency (JAEA), are properly offered to the implementations and the safety regulations. For the sake of this, JAEA has proceeded with the project in collaboration with experts from domestic and overseas research organizations.
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.
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.
Ishimaru, Tsuneari; Ogata, Nobuhisa; Shimada, Akiomi; Kokubu, Yoko; Asamori, Koichi; Niwa, Masakazu; Watanabe, Takahiro; Saiga, Atsushi; Sueoka, Shigeru; Yokoyama, Tatsunori; et al.
JAEA-Review 2017-022, 45 Pages, 2017/12
JAEA-Review-2017-022.pdf:1.42MB
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 2017. The objectives and contents in fiscal year 2017 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.
Ishimaru, Tsuneari; Umeda, Koji*; Yasue, Kenichi; Kokubu, Yoko; Niwa, Masakazu; Asamori, Koichi; Watanabe, Takahiro; Yokoyama, Tatsunori; Fujita, Natsuko; Shimizu, Mayuko; et al.
JAEA-Research 2016-023, 91 Pages, 2017/02
JAEA-Research-2016-023.pdf:13.33MB
This annual report documents the progress of research and development (R&D) in the 1st 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.
Kato, Aitaro*; Saiga, Atsushi; Takeda, Tetsuya*; Iwasaki, Takaya*; Matsuzawa, Toru*
Earth, Planets and Space (Internet), 66(1), p.86_1 - 86_8, 2014/12
Times Cited Count：22 Percentile：55.81(Geosciences, Multidisciplinary)To understand the mechanism of an intensive non-volcanic seismic swarm in the Kii Peninsula, Japan, we used a dense seismic linear array to measure fine-scale variations of seismic velocities and converted teleseismic waves. A low-velocity anomaly confined to just beneath the seismic swarm area is clearly imaged, which spatially correlates with an uplifted surface area, and a highly conductive and strong attenuative body. These results suggest that fluids such as partial melt or water are present beneath this non-volcanic seismic swarm area. It is notable that the island arc Moho below the seismic swarm area is at depths of ca. 32 km in the northern part of the seismic swarm area, and shallows to ca. 20 km towards the south, due to an upwardly raised structure of serpentinized mantle wedge. In addition, we show that hydrated oceanic crust of the subducting Philippine Sea slab is characterized by low-velocities with a high Poisson's ratio at depths shallower than 40 km. Water released from the subducting oceanic crust could cause serpentinization of the mantle wedge and infiltration into the forearc base of the overlying plate. The interaction between dehydration of the subducting oceanic crust and hydration of the mantle wedge and overlying plate exerts an important role in driving the non-volcanic seismic swarm activity in the Kii Peninsula.
He/
He ratios in the San-in shear zone, southwest JapanUmeda, Koji*; Asamori, Koichi; Saiga, Atsushi; Nishimura, Takuya*
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Watanabe, Tsuyoshi; Saiga, Atsushi; Asamori, Koichi
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Watanabe, Tsuyoshi; Saiga, Atsushi; Asamori, Koichi
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Watanabe, Tsuyoshi; Asamori, Koichi; Okuyama, Satoshi*; Saiga, Atsushi; Umeda, Koji*
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Watanabe, Tsuyoshi; Saiga, Atsushi; Asamori, Koichi; Shimada, Akiomi; Umeda, Koji*
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Watanabe, Tsuyoshi; Saiga, Atsushi; Asamori, Koichi; Ogawa, Hiroki; Shimada, Akiomi; Umeda, Koji*
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Hiratsuka, Shinya; Saiga, Atsushi; Asamori, Koichi
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Hydrothermal activity is generated in the Kii Peninsula although it is a non-volcanic region. High helium isotope ratio, low seismic velocity and low resistivity suggest that hydrothermal water is originated from deep fluid. This study attempt to estimate the migration process of deep fluid using seismological method so-called S-wave splitting analysis. The result shows that high anisotropic region may correspond to migration process of deep fluid, but it is necessary for more accumulation of seismological data.
