Potassium-Argon (K-Ar) dating for fault gouge samples in the Tono Geoscience Center

Tamura, Hajimu*; Shibata, Kenji*; Takahashi, Naoya; Niwa, Masakazu

JAEA-Testing 2017-001, 52 Pages, 2017/03

JAEA-Testing-2017-001.pdf:2.36MB

It is essential to understand the activity of faults in and around a target area to assess the long-term geosphere stability for geological isolation. Potassium-Argon (K-Ar) dating of fault gouge has been conducted in Tono Geoscience Center as one of the dating technique for faulting. This report includes methods for sample preparation, analyses, and age calculation on the K-Ar dating. This can contribute to an evaluation of calculated K-Ar ages.

Thermal constraints on clay growth in fault gouge and their relationship with fault-zone evolution and hydrothermal alteration; Case study of gouges in the Kojaku Granite, Central Japan

Niwa, Masakazu; Shimada, Koji; Tamura, Hajimu*; Shibata, Kenji*; Sueoka, Shigeru; Yasue, Kenichi; Ishimaru, Tsuneari; Umeda, Koji*

Clays and Clay Minerals, 64(2), p.86 - 107, 2016/04

https://doi.org/10.1346/CCMN.2016.0640202

no abstracts in English

Research on geosphere stability for long-term isolation of radioactive waste; Scientific programme for fiscal years 2015-2021

Umeda, Koji; Yasue, Kenichi; Kokubu, Yoko; Niwa, Masakazu; Asamori, Koichi; Fujita, Natsuko; Shimizu, Mayuko; Shimada, Akiomi; Matsubara, Akihiro; Tamura, Hajimu; et al.

JAEA-Review 2015-012, 43 Pages, 2015/08

JAEA-Review-2015-012.pdf:1.24MB

The concept of geological disposal of high-level radioactive waste (HLW) in Japan is based on a multibarrier system which combines a stable geological environment with an engineered barrier system. Potential geological host formations and their surroundings are chosen, in particular, for their long-term stability, taking into account the fact that Japan is located in tectonically active zone. This report is to outline 7 years plan (fiscal years 2015-2021) of research and development (R&D) for geosphere stability for long-term isolation of the HLW in JAEA. Background of this research is clarified with the necessity and the significance, and the past progress in this report. The objectives, outline, contents and schedule during the next 7 years are described in detail. 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.

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal years 2012

Yasue, Kenichi; Asamori, Koichi; Niwa, Masakazu; Hanamuro, Takahiro; Kokubu, Yoko; Sueoka, Shigeru; Makuuchi, Ayumu; Ikuta, Masafumi; Matsubara, Akihiro; Tamura, Hajimu; et al.

JAEA-Research 2013-047, 109 Pages, 2014/03

JAEA-Research-2013-047.pdf:6.81MB

This annual report documents the progress of R&D in the 3rd fiscal year during the JAEA 2nd Midterm Plan (FY 2010 - 2014) 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 for selecting suitable sites in geosphere stability, (2) development, application and verification of prediction models for evaluating the changes of geological environment in thermal, hydraulic, mechanical and geochemical conditions for a long period of time, and (3) development of new dating techniques for providing information about geologic history and the timing of geologic events. In this paper, the current status of R&D activities with previous scientific and technological progress is summarized.

The First loading fuel elements and power-up for JRR-2

JRR-2 Control Office; Kambara, Toyozo; Shoda, Katsuhiko; Hirata, Yutaka; Shoji, Tsutomu; Kohayakawa, Toru; Morozumi, Minoru; Kambayashi, Yuichiro; Shitomi, Hajimu; Kokanezawa, Takashi; et al.

JAERI 1027, 57 Pages, 1962/09

JAERI-1027.pdf:4.76MB

no abstracts in English

Treatment and analysis of the water and gas in JRR-2

JRR-2 Operations Office; Kambara, Toyozo; Shoda, Katsuhiko; Hirata, Yutaka; Shoji, Tsutomu; Haginoya, Kinichi; Kohayakawa, Toru; Yamaki, Jikei; Yokota, Mitsuo; Horiki, Oichiro; et al.

JAERI 1024, 79 Pages, 1962/08

JAERI-1024.pdf:5.66MB

no abstracts in English

Geophysical and geochemical signatures associated with mantle fluids beneath an active shear zone, southwest Japan

Shimizu, Mayuko; Umeda, Koji; Asamori, Koichi; Makuuchi, Ayumu; Sueoka, Shigeru; Tamura, Hajimu

no journal, , 

In 1997, the Kagoshima earthquake doublet, consisting of two closely associated Mw 6 strike-slip events, five km and 48 days apart, has occurred in southwest Japan. The location is where an E-W trending discontinuity along 32N latitude on southern Kyushu Island is clearly defined in GPS velocities, indicating the presence of a highly active left-lateral shear zone. However, there have not been any obvious indications of active faulting at the surface prior to the earthquake doublet, which could be associated with this shear zone. Three-dimensional inversion of magnetotelluric sounding data obtained in the source region of the earthquake doublet reveals a near-vertical conductive zone with a width of 20 km, extending down to the base of the crust and perhaps into the upper mantle toward the Okinawa trough. The prominent conductor corresponds to the western part of the active shear zone. Elevated He/He ratios in groundwaters sampled from hot spring and drinking water wells suggest the emission of mantle-derived helium from the seismic source region. The geophysical and geochemical observations are significant indications that the invasion of mantle fluids into the crust, driven by upwelling asthenosphere from the Okinawa trough, triggers the notable left-lateral shearing in the zone in the present-day subduction system. In addition, the existence of aqueous fluids in and below the seismogenic layer could change the strength of the zones, and alter the local stress regime, resulting in the occurrence of the 1997 earthquake doublet.

Clay mineral composition and K-Ar ages from fault gouges in the Kojaku Granite, Tsuruga Peninsula

Niwa, Masakazu; Shimada, Koji; Sueoka, Shigeru; Tamura, Hajimu; Shibata, Kenji

no journal, , 

X-ray diffraction analysis and K-Ar dating were applied for fault gouges in the late Cretaceous Kojaku Granite, Tsuruga Peninsula. The fault gouge includes smectite, 1M type illite, and kaolinite, based on the X-ray diffraction analysis. The K-Ar dating shows approximately 39 to 45 Ma for the 0.1 m size fractions separated from the gouges. The K-Ar ages and the reconstructed cooling history of the granite suggest that the 1M illite was formed at 60 to 110 C (approximately 2 to 4 km in depth for 30 C/km of geothermal gradient).

Study on faulted materials for an assessment of fault activity in JAEA; Geochronological and thermochronological approaches

Niwa, Masakazu; Tamura, Hajimu*; Sueoka, Shigeru; Shimizu, Mayuko

no journal, , 

no abstracts in English

High-precision noble gas isotope analysis using multi collector noble gas mass spectrometer; Study toward practical use of noble gas method for age determination of groundwater

Kokubu, Yoko; Tamura, Hajimu*; Yokoyama, Tatsunori

no journal, , 

High precision noble gas isotope analysis of groundwater is useful to estimate age and origin of groundwater. This study presents measurement of isotope ratio using a multi-collector noble gas mass spectrometer with six collectors and an auto noble gas purification instrument. The results of measurement of neon and helium in trial samples suggest that the mass spectrometer with high precision enable the noble gas isotope analysis of groundwater.