Reaction path analysis to sodium-water chemical reaction field using laser diagnostics

Tamura, Kenta*; Deguchi, Yoshihiro*; Muranaka, Ryota*; Kusano, Koji*; Takata, Takashi*; Kikuchi, Shin; Kurihara, Akikazu

Proceedings of 24th International Symposium on Transport Phenomena (ISTP-24) (USB Flash Drive), 5 Pages, 2013/11

The purpose of this study aims to clarify the gas phase sodium-water reaction path and reaction products. The counter-flow diffusion experiment device is in the form of introducing the argon-based water vapor from the top of depressurized reaction chamber to the liquid sodium pool. Na, Na, HO, and reaction products in the counter-flow sodium-water reaction field were measured using laser diagnostics. The temperature controlled device was also improved to reduce the condensation of Na in the reaction zone for the better measurement performance. The main product in the sodium-water reaction was determined to be NaOH from the experimental results and its reaction path was discussed using Na-HO elementary reaction analysis.

Release of mantle and crustal helium from a fault following an inland earthquake

Umeda, Koji; Asamori, Koichi; Kusano, Tomohiro

Applied Geochemistry, 37, p.134 - 141, 2013/10

https://doi.org/10.1016/j.apgeochem.2013.07.018

This study was undertaken to elucidate spatial and temporal changes of He/He ratios around a source region before and after an inland earthquake using both new and existing helium isotope data from hot spring and drinking water wells. Most gas samples near the seismic source region are characterized by increase in postseismic He/He ratios. In contrast, the postseismic ratios decrease by up to about 30% away from the seismic source region. Episodic faulting could release accumulated radiogenic helium from host rocks, or enhance the transfer of mantle volatiles through permeable fault zones, such that subsequent fluid flow proximal to the source region could then explain the spatio-temporal variations in He/He ratios.

Tectonic shortening and coeval volcanism during the Quaternary, northeast Japan arc

Umeda, Koji; Ban, Masao*; Hayashi, Shintaro*; Kusano, Tomohiro

Journal of Earth System Science, 122(1), p.137 - 147, 2013/02

https://doi.org/10.1007/s12040-012-0245-z

From a compilation and analysis of stratigraphy, radiometric age and data on erupted magma volumes, 176 eruptive episodes identified from 69 volcanoes so far, indicate that notable changes in eruption style, magma discharge rates and distribution of eruptive centers occurred around 1.0 Ma. Before ca. 1.0 Ma in northeast Japan, large-volume felsic eruptions were dominant, forming large calderas in the frontal arc, a region of low crustal strain rate. After ca. 1.0 Ma to the present, the calc-alkaline andesite magma eruptions in the frontal and rear arcs, synchronous with crustal shortening characterized by reverse faulting, resulting in stratovolcano development along narrow uplifted zones.

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal years 2011

Asamori, Koichi; Niwa, Masakazu; Hanamuro, Takahiro; Yamada, Kunimi; Kusano, Tomohiro; Makuuchi, Ayumu; Takatori, Ryoichi; Kokubu, Yoko; Matsubara, Akihiro; Ishimaru, Tsuneari; et al.

JAEA-Research 2012-024, 132 Pages, 2012/09

JAEA-Research-2012-024.pdf:15.68MB

This annual report documents the progress of R&D in the 2nd 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 planed 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.

Research plan on geosphere stability for long-term isolation of radioactive waste; Scientific programme for fiscal years 2012

Asamori, Koichi; Niwa, Masakazu; Hanamuro, Takahiro; Yamada, Kunimi; Kusano, Tomohiro; Makuuchi, Ayumu; Takatori, Ryoichi; Kokubu, Yoko; Ishimaru, Tsuneari; Umeda, Koji

JAEA-Review 2012-024, 44 Pages, 2012/07

JAEA-Review-2012-024.pdf:1.29MB

The concept of geological disposal of HLW in Japan is based on a multi-barrier system which combines a stable geological environment with a robust 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 a tectonically active zone. This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of HLW in JAEA, in fiscal year 2012. The objectives and contents in fiscal year 2012 are described in detail based on the outline of 5 years plan (fiscal years 2010-2014). In addition, the planed 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.

Research plan on geosphere stability for long-term isolation of radioactive waste; Scientific programme for fiscal years 2011

Yasue, Kenichi; Asamori, Koichi; Kusano, Tomohiro; Kokubu, Yoko; Tanikawa, Shinichi; Niwa, Masakazu; Hanamuro, Takahiro; Yamasaki, Seiko; Yamada, Kunimi; Ishimaru, Tsuneari; et al.

JAEA-Review 2011-023, 43 Pages, 2011/07

JAEA-Review-2011-023.pdf:1.84MB

The concept of geological disposal of 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 a tectonically active zone. This report is a plan of research and development (R&D) for geosphere stability for long-term isolation of HLW in JAEA, in fiscal year 2011. The objectives and contents in fiscal year 2011 are described in detail based on the outline of 5 years plan (fiscal years 2010-2014). 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.

A Large intraplate earthquake triggered by latent magmatism

Umeda, Koji; Asamori, Koichi; Negi, Tateyuki; Kusano, Tomohiro

Journal of Geophysical Research, 116(B1), p.B01207_1 - B01207_12, 2011/01

https://doi.org/10.1029/2010JB007963

A magnitude () 7.3 intraplate earthquake occurred in the western Tottori area, southwest Japan, on 6 October 2000, where there was no apparent prefaulting subsurface indication of the source fault of the 2000 earthquake. Magnetotelluric soundings were taken in and around the aftershocks occurred in order to image 3D electrical resistivity structure at depths of up to 40 km, which could indicate an anomalous conductor in the crust to the upper mantle on the southwest side of the source fault. Free gas and dissolved gases collected from groundwater wells around the seismic source region are characterized by He/He ratios several times higher than the atmospheric value. Although alkali basalts of early Pleistocene age are sparsely distributed in the western Tottori area, the observed He/He ratios are higher than the calculated He/He ratio derived from the ancient magmatism, considering post-extrusive radiogenic ingrowth of He by decay of U and Th included in the magma. Therefore, it is concluded that the geophysical anomaly imaged to the southwest of the source fault is attributed to latent magmatism in the present-day subduction system. Aqueous fluids separated from the cooling crustal magma could cause deep low-frequency earthquakes around the Moho discontinuity and migrate into the brittle upper crust. In addition, the presence of aqueous fluid is expected to weaken the crustal materials. Locally anelastic deformation, implying notable compressive deformation in the E-W direction, was observed in the region where aftershocks were distributed. Under overpressure conditions, the existing fault could serve as a pathway for aqueous fluids expelled from magma with high He/He ratios, so that the upwelling of overpressurized fluids toward the Earth's surface results in the emanation of groundwaters with high He/He ratios along the trace of the source fault segments.

Research on geosphere stability for long-term isolation of radioactive waste; Scientific programme for fiscal years 2010-2014

Umeda, Koji; Ishimaru, Tsuneari; Yasue, Kenichi; Asamori, Koichi; Yamada, Kunimi; Kokubu, Yoko; Hanamuro, Takahiro; Tanikawa, Shinichi; Kusano, Tomohiro

JAEA-Review 2010-030, 48 Pages, 2010/09

JAEA-Review-2010-030.pdf:1.42MB

The concept of geological disposal of 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 a tectonically active zone. This report is to outline 5 years plan (fiscal years 2010-2014) of research and development (R&D) for geosphere stability for long-term isolation of the high-level radioactive waste in JAEA. Background of this research are clarified with the necessity and the significance, and the past progresses in this report. The objectives, outline, contents and schedule during the next 5 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 long-term stability of geological environments in FY2007

Kusano, Tomohiro; Nohara, Tsuyoshi; Umeda, Koji; Ishimaru, Tsuneari; Hanamuro, Takahiro; Saito, Tatsuo; Yasue, Kenichi; Niwa, Masakazu; Shimada, Koji; Yamada, Kunimi; et al.

JAEA-Research 2009-022, 47 Pages, 2009/09

JAEA-Research-2009-022.pdf:48.94MB

The Japanese islands are located in the tectonically active Circum-Pacific Mobile Belt. As a result, Japan has a high frequency of earthquakes and eruptions. Special consideration is given to the long-term stability of the geological environment, taking into account volcanism, faulting, uplift, denudation, climatic change and sea-level change in Japan. Development of research/prediction technologies for geotectonic events has been carried out to evaluate the long-term stability of the geological environment in Japan. In fiscal year 2007, we carried out the following researches, to confirm existence of the phenomena that have influences on geological disposal system (e.g., active faulting, volcanism), and to develop the investigation techniques to reconstruct the history of these phenomena. For studies of faulting and seismic activity, we developed the investigation techniques to research distribution of crush zone, process of faulting, activity, and so on. For volcanological and geothermal studies, we developed a technique for detecting crustal magma and/or geothermal fluid in deep underground. For studies of uplift/denudation and climatic/sea-level changes, we extracted investigation techniques for landform developments and uplift rate with river terraces.

Gas yield and mechanical property of super insulator (polyimide and polyester) after ray irradiation

Teshigawara, Makoto; Kusano, Joichi; Morishita, Norio; Maekawa, Fujio; Kato, Takashi; Hosoyama, Kenji*; Hara, Kazufumi*; Kojima, Yuji*

Teion Kogaku, 41(3), p.99 - 104, 2006/03

https://doi.org/10.2221/jcsj.41.99

Japanese intense spallation neutron source (JSNS) driven by 3 GeV protons with power of 1 MW is constructed under the joint project of Japan Atomic Energy Agency and High Energy Accelerator Research Organization. Supercritical hydrogen of around 20K with 2 MPa is selected as a neutron moderator material and cryogenic hydrogen transfer lines are constructed from the moderators to the refrigerator. Then, a super insulator (SI) is adopted to reduce heat load in the hydrogen transfer lines. We performed irradiation test of SI using Co ray to evaluate the irradiation effect. Two kinds of super insulator (polyimide and polyester) coated both sides by aluminum were irradiated. After ray irradiation, tensile test and gas yield measurement of super insulator were performed. Polyester based SI became brittle at about 10 MGy, on the other hand, polyimide based SI did not loss ductility so much even 80 MGy. Polyester based SI generated gas yield higher than that of polyimide based SI about one order of magnitude. We developed the gas analysis method by using a Q-mass and a mass-flow, providing to identify the unknown gas (i.e. HO) effectively compared to a gas chromatography method.