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Kato, Toshihiro; Iwatsuki, Teruki; Nakata, Kotaro*; Hasegawa, Takuma*
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no abstracts in English
Sasao, Eiji
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According to "Long-term Energy Supply and Demand Outlook" released on July 2015, the dependence on the nuclear power plants is planned to be approximately 20 to 22 % of the electric power supply in FY2030. Because uranium is limited resource, it is useful to consider the long-term supply. Information on uranium resources are periodically reported by international and national organizations. For example, OECD/NEA and IAEA have jointly prepared periodic updates (currently every two years) on world uranium resources, production and demand (known as the "Red Book"). In this presentation, supply and demand of uranium are reviewed based mainly on Red Book, and then future possibility on increase in uranium resources in Canada and Australia is discussed. In these countries, discovery of new deposit and increase in resources are quite possible by progress of exploration.
Sueoka, Shigeru; Tagami, Takahiro*; Kohn, B.*; Fukuda, Shoma*
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no abstracts in English
Ishimaru, Tsuneari; Shimada, Koji; Sueoka, Shigeru; Yasue, Kenichi; Niwa, Masakazu; Umeda, Koji
no journal, ,
In JAEA, geological investigation of fracture zones has been carried out at the Monju site based on the instruction received from the Nuclear Regulation Authority. Results of the investigation, it has shown that no clear evidence was observed to indicate that on-site fracture zones are active faults. In the activity evaluation of the on-site fracture zones, we examined cross-cutting relationships of fractures in detail, and we estimated that these fracture zones are older small-scale geological structure which was formed under the high-temperature environment of the deep part before exposure of the granitic body from the microscopic observation of the plastic deformation of biotite grains in the fracture zones and the deformation twins in the calcite veins along the fracture zones. This investigation of fracture zones is considered one of good examples shown that it is possible to evaluated activity of fracture zones in granite.
Watanabe, Takahiro; Kokubu, Yoko; Murakami, Hiroaki; Yokoyama, Tatsunori; Amamiya, Hiroki; Mizuno, Takashi; Kubota, Mitsuru; Iwatsuki, Teruki
no journal, ,
Chronological and geochemical studies of fracture filling calcite in rocks provide the information for changes in geochemical condition, such as redox potential and pH in geological environments. Because the calcite can be found as common filling minerals in the natural samples, age zoning and spatial distribution of chemical composition in the calcite could be a wide-use indicator to reconstruct the past environmental changes. Radiometric (U-Pb) dating in a micro scale area (less than 10 micrometer) on the filling mineral surface by laser ablation-inductively coupled plasm mass spectrometry system (LA-ICPMS) has been applied to geological samples. Additionally, past redox potential has been estimated by Fe contents in the carbonates, which is based on the distribution coefficient of Fe between calcite deposit and groundwater. In this study, we evaluated the possibility of in-situ radiometric dating for the filling minerals by LA-ICPMS and redox potential reconstruction by the theoretical calculation using the distribution coefficient.
Matsuoka, Toshiyuki; Komatsu, Tetsuya; Yasue, Kenichi; Onoe, Hironori; Oyama, Takuya; Iwatsuki, Teruki; Sasao, Eiji; Umeda, Koji
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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 
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.
Cs behaviors in reservoirs during rainfall eventsKurikami, Hiroshi; Kitamura, Akihiro
no journal, ,
In this study, to understand the sensitivity of intensity and duration of flood events to discharges of sediment and radioactive cesium during flood events, we performed sensitivity analyses by using the FLESCOT code. The results showed that the discharge proportions depended on sediment size, event intensity and event duration. The proportions of sediment/Cs discharges increase, as event duration is shorter/heavier. The silt component is a main carrier of radioactive cesium in larger events, while the clay-sorbed and dissolved forms are dominant in smaller events. In heavier events, resuspension of bed sediment took place.
Onoe, Hironori; Komatsu, Tetsuya; Yasue, Kenichi; Iwatsuki, Teruki; Takeuchi, Ryuji; Kato, Tomoko; Sasao, Eiji; Umeda, Koji
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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.
Yasue, Kenichi; Sasao, Eiji; Onoe, Hironori; Iwatsuki, Teruki; Kato, Tomoko; Takeuchi, Ryuji; Kokubu, Yoko; Asamori, Koichi; Umeda, Koji
no journal, ,
Geosphere stability project is being carried out by Japan Atomic Energy Agency in order to establish techniques for investigation, analysis and assessment of the long-term evolution of geological environments, taking into account long-term geological phenomena such as volcanism, faulting, uplift, denudation, climate change, and sea-level change. This project is being conducted under a contract with Agency of Natural Resources and Energy, part of Ministry of Economy, Trade and Industry of Japan as part of its R&D supporting program for developing technology of geological disposal of high-level radioactive waste. This project has the development of a numerical model "geological-evolutionary model" expressing a change of the geological environments and the development of "innovative elemental technique" that is elemental technology required for model construction.
Shimizu, Mayuko; Shibata, Kenji; Suzuki, Kazuhiro; Sueoka, Shigeru; Niwa, Masakazu
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The CHIME dating has been performed on JEOL JXA-8530F FE-EPMA introduced in Tono Geoscience Center of JAEA. The R = 100 mm spectrometer is desirable for quantitative determination of trace Pb, giving an intrinsic response 3 to 5 times higher than that of the conventional R = 140 mm spectrometer. JXA-8530F equipped with three R = 100 and two R = 140 mm spectrometers significantly shortens an analyzing time. The age values by this advanced procedure of monazites from the Cooma granodiorite and the Kojaku granite correspond to the values of the previous researches within the error range. In our presentation we also show the CHIME age of the Steenkampskraal monazite, which was dated by SHRIMP as 1033 Ma. In addition, a quick heavy mineral identification method, which has been established as well, is introduced.
Takeuchi, Ryuji; Onoe, Hironori; Yasue, Kenichi
no journal, ,
In geological disposal for high-level radioactive waste, time scale for assessment is equal to or more than several hundreds of thousand years. During this time, the surface hydrological environment might change. Especially, changes of precipitation, evapotranspiration and runoff volume might cause a change of groundwater recharge rate (GRR), which is upper boundary condition of groundwater flow for deep underground. This study shows the method to estimate GRR considering the influence of changes for climate condition and landform condition as an example in Tono area. The GRRs of 0.45 Ma are estimated 118% to 237% of the current GRR, and the GRRs of 0.14 Ma are estimated 81% to 196% of the current GRR. In the result of current topography in the glacial period, the recharge rate is estimated 58% to 72% of the current GRR. However it's not possible to estimate the runoff volume based on the topography of 1.0 Ma, which is estimated poor undulations and flat terrains.
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.
Ishibashi, Masayuki; Iwasaki, Riyo; Hama, Katsuhiro
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no abstracts in English
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.
Watanabe, Tsuyoshi; Okuyama, Satoshi; Asamori, Koichi; Umeda, Koji
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no abstracts in English
Asamori, Koichi; Hama, Yuki; Umeda, Koji
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no abstracts in English
Sato, Tatsuhiko; Ishii, Mamoru*; Kataoka, Ryuho*; Kubo, Yuki*; Minoshima, Takashi*; Miyoshi, Yoshizumi*; Nagamatsu, Aiko*; Shiota, Daiko*; Takashima, Takeshi*; Yasuda, Hiroshi*
no journal, ,
Forecast of radiation doses for astronauts as well as aircrews due to the exposure to solar energetic particles (SEP) is one of the greatest challenges in space weather research. In last 5 years, we have developed a WArning System for AVIation Exposure to Solar energetic particles: WASAVIES. In this system, the SEP fluxes incident to the atmosphere are calculated by physics-based models, and they are converted to radiation doses using a database developed on the basis of air-shower simulation. However, it takes approximately 2.5 hours to determine the parameters used in the physics-based models after the detection of GLEs, and thus, the current WASAVIES cannot predict doses during the peak of GLEs. Therefore, we are trying to reduce the time for evaluating the parameters, as well as to develop a nowcast system for the radiation dose due to SEP exposure, under the framework of Project for Solar-Terrestrial Environment Prediction (PSTEP) in Japan. A brief outline of WASAVIES together with our future strategy will be presented at the meeting.
Shimada, Koji; Ishimaru, Tsuneari; Sueoka, Shigeru; Terusawa, Shuji; Yasue, Kenichi; Niwa, Masakazu; Umeda, Koji
no journal, ,
Diverse situation of outcropping crush zones around important building constructions need upgrading of activity evaluation method without the use of overlying sediments. The method using the cross-cutting relations among geologic features in basement rocks is promising. However, minor crush zones without cross-cutting relation are frequently observed. An activity evaluation of such minor crush zone was carried out in one outcrop. The confirmation of an extension of the crush zone, age estimation of young overlying sediments, comparison of sense of shear of clay vein, comparison of outcrop morphology with another crush zone, and clay grain-size measurement of the near active fault and the crush zone are carried out. The results suggest that the crush zone is not an active fault or a weak zone which slips accompanied with the active zone.
Yamada, Ryuji*; Kokubu, Yoko; Wakatsuki, Tsuyoshi*; Yasue, Kenichi
no journal, ,
Mass movements and fault movements are natural phenomena to change the local topography. Reconstruction of the movement histories and evaluation of long-term stability of topographies are crucial to assess the geological environment in future. History reconstruction based on radiocabon dating of plant material recovered from sediment deposited by the past movements requires the compilation and the comparison of existing data measured by different analysts with different methods. We compared the results of radiocarbon ages measured at different laboratories with various chemical pretreatments, using plant material samples. For older samples (about 45000 BP), dispersion in ages is greater than measurement uncertainty. However the order of weighted mean ages for each sample agrees well with stratigraphic sequence at the sampling site. It is therefore thought that the influence of the systematic error due to a specific experimental conditions is small.
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.