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Sueoka, Shigeru; Ikeda, Yasutaka*; Kano, Kenichi*; Tsutsumi, Hiroyuki*; Tagami, Takahiro*; Kohn, B. P.*; Hasebe, Noriko*; Tamura, Akihiro*; Arai, Shoji*; Shibata, Kenji*
no journal, ,
no abstracts in English
Hayashida, Kazuki; Kato, Toshihiro; Kubota, Mitsuru; Iwatsuki, Teruki
no journal, ,
This study aims to understand the hydrogeochemical condition and dominant process after the drift closure. To this aim the drift closure experiment was conducted in the granitic rock of 500 m below ground level of Mizunami Underground Research Laboratory. The groundwater chemistry such as major chemical component, pH and redox condition has been monitored in closed drift for 1 year. Dominant processes on chemical evolution of isolated groundwater in the closed drift were identified as follows; continuous replacement by surround rock water, microbial reduction, water-mineral interactions with evaporite, shotcrete and granite.
He/
He ratios in the San-in shear zone, southwest JapanUmeda, Koji*; Asamori, Koichi; Saiga, Atsushi; Nishimura, Takuya*
no journal, ,
no abstracts in English
Ozaki, Yusuke; Onoe, Hironori; Takayama, Yusuke; Takayasu, Kentaro; Takeuchi, Ryuji
no journal, ,
The purpose of this study is to identify factors that dominate the saturation in bentonite mixture material during drift closure test. The bentonite mixture buried in two pits in the test drift is monitored to evaluate its hydro-mechanical behavior during the test. To clear the factors effective to the saturation in the mixture, we perform numerical simulation focusing on the effect of swelling, hydraulic conductivity and unsaturated characteristics in the mixture. Our simulation results show that the unsaturated characteristics of the mixture have the greatest effect on the saturation in the mixture. For accurate estimation of saturation change in the mixture, unsaturated characteristics data is key information.
Martin, A.*; Asamori, Koichi; Ishimaru, Tsuneari
no journal, ,
Assessing the stability of the geological environment including the spatio-temporal distribution of active faulting is of particular concern in the context of site selection of critical facilities such as nuclear power plants, spent fuel reprocessing facities as well as geological repositories or surface storage facilities of radioactive waste etc. Understanding the spatial distribution of active faulting is a particular challenge for geologists in that not all active faults have surface expressions. We present here a probabilistic approach based on Bayesian statistics that can be used to combine multiple datasets (in this case historic seismic data and helium isotopes sampled from wells) to produce hazard maps showing the likelihood of active faults existing or not.
Niizato, Tadafumi; Sasaki, Yoshito; Mitachi, Katsuaki*
no journal, ,
The outflow of 
Cs from the mountainous forest floor was estimated in the Abukuma Mountains, Fukushima. The outflow rates are decreased with a cover rate of the forest floor by a litter layer. The result shows the important role of the litter layer and undergrowth on a migration control of the radiocesium outflow from the forest floor.
-ray spectra obtained by airborne radiation monitoringOchi, Kotaro; Sasaki, Miyuki; Ishida, Mutsushi*; Sato, Tomohiko*; Hamamoto, Shoichiro*; Nishimura, Taku*; Sanada, Yukihisa
no journal, ,
A large amount of radiocesium (
Cs & Cs) were released into the atmosphere as a result of 2011 Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. To estimate the impact of the accident to the environment, dose rate around FDNPP have been measured by MEXT. Dose rate nearby FDNPP, however, still stay high even though decontamination work was carried out, which means it is necessary to develop an effective decontamination method promptly. Information of depth profile of radiocesium in soil is required to realize it, though, most of measurement methods have trouble due to collection and measurement of soil samples. As we have developed the radiation measurement techniques using unmanned aerial vehicle to measure dose rate distribution over wide areas for years, we attempt to establish the estimation method of depth profile of radiocesium in soil based on characteristics of -ray spectra obtained by airborne radiation monitoring in this paper.
Sasaki, Miyuki; Ishizaki, Azusa; Sanada, Yukihisa
no journal, ,
Since accident of the Fukushima Daiichi Nuclear Power Station (FDNPS), some unmanned vehicle was applied for radiation measurement around the FDNPS. JAEA is developing a method using a small multi-rotor helicopter (micro UAV) for measurement of radiation in the environment. The micro UAV is expected to be useful to measure the radiation distribution at small areas easily. In the conventional method, there are some premises to convert from count rate to dose rate at 1 m above the ground and they make it difficult to measure precise dose rate by airborne monitoring system at mountains and uneven places. Besides, the influence of the radiation from a structure and tree on the ground is not ignored at the low altitude less than 50 m that micro UAV can fly stably. In this study, the successive approximation method which is used in the medical radiation such as Positron Emission Tomography is attempted to apply to environmental radiation measurement.
Shimada, Koji; Sueoka, Shigeru; Terusawa, Shuji
no journal, ,
Examples of meso- and microstructures of non-active minor crush zones are useful to an activity evaluation of minor crush zone. We show meso- and microstructures from minor crush zones in granite located near the prototype of fast breeder reactor Monju. A 1-cm-thick cataclasite zone exhibiting weakly localized strain was observed. Dynamic recrystallization of quartz is not observed. Biotite in the zone is typically stretched and defining foliation of the cataclasite. The coexistence of the intracrystalline plastic deformation of biotite and the crushing of other granular minerals in the foliated cataclasite indicates that the most recent slip is the semi-brittle flow. The deformation microstructure of biotite indicates that the deformation condition of the latest slip is high-temperature and the minor crush zone is non-active fault.
Watanabe, Takayoshi; Ishii, Yasuo; Niizato, Tadafumi; Sasaki, Yoshito; Mitachi, Katsuaki*
no journal, ,
no abstracts in English
Sano, Asami; Hattori, Takanori; Funakoshi, Kenichi*; Abe, Jun*; Machida, Shinichi*
no journal, ,
In this study, we investigated the evolution of hydrogen bond geometry in distorted rutile type mineral guyanite under pressure using neutron diffraction. This mineral is known to have a large difference in the unit cell volume between CrOOH and CrOOD even at ambient pressure. However the previous X-ray diffraction study (Sano-Furukawa et al., 2012) has indicated that this volume difference merges at around 5 GPa. We attempt to explain the cause of this phenomenon from the crystallographic view. Neutron diffraction experiment was conducted at the PLANET beamline in J-PARC by using Paris-Edinburgh press. We observed the change in deuterium distribution from order to disorder at this pressure. In the presentation, the relation between the change of hydrogen bond geometry and reduced partition function ratio will be discussed.
Sasao, Eiji
no journal, ,
Science Council of Japan mentioned importance of establishment of technology to search rock body with minor fractures. It is significant to understand the fracture frequency in many rock bodies in Japan. The data widely obtained such as by borehole investigation should be available to characterise the fracture frequency. In this study, the speaker discussed the relationship between RQD (Rock Quality Designation) and fracture frequency focused on the Toki granite, central Japan. Fracture data were obtained by investigations in the boreholes drilled from the ground surface and the underground research galleries. There is a significant correlation between RQD value and fracture frequency. The data are then divided into 100 meters length and those RQD values are compared with fracture frequency. The RQD value is also associated with fracture frequency. This result indicates that the method proposed in this study can be ubiquitously applied to various lengths of borehole.
Murakami, Hiroaki; Watanabe, Takahiro; Iwatsuki, Teruki
no journal, ,
Long-term evolution of granitic-groundwater chemistry was calculated by thermodynamics analysis. This analysis is taking into account the actually-observed mineral assemble and residence time of groundwater. The result of this analysis suggest that long-term evolution of pH would be alkaline in case meteoric water remain a major part of recharge source of granitic-groundwater.
Sueoka, Shigeru
no journal, ,
no abstracts in English
Sato, Tatsuhiko; Kataoka, Ryuho*; Yasuda, Hiroshi*; Kubo, Yuki*; Ishii, Mamoru*; Miyake, Shoko*; Park, I.*; Miyoshi, Yoshizumi*
no journal, ,
Estimation 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. We are therefore developing a WArning System for AVIation Exposure to Solar energetic particle (WASAVIES), under the framework of Project for Solar-Terrestrial Environment Prediction (PSTEP). In the system, the SEP fluxes incident to the atmosphere are calculated by physics-based models. Thus, WASAVIES can estimate not only the current value but also time variation of the aircrew doses after a GLE event occurs. A brief outline of WASAVIES together with the status of on-going research subjects such as development of the automatic calculation algorithm will be presented at the meeting.
Kurikami, Hiroshi; Malins, A.
no journal, ,
Despite its affinity for binding to soil, radiocesium gradually migrates deeper into the ground over time. This results in a faster rate of reduction of air dose rates than would be expected by radioactive decay. Using radiation transport methods, this study calculated the trajectory of air dose rates over time given the evolution in the depth profile predicted by the model based on an advection-dispersion equation coupled with kinetic models of reversible/irreversible sorption. The results indicate a faster reduction in dose rates than the rate of radioactive decay in the first ten years following fallout, as there is a gradual migration of radiocesium in soil over this period. The rate of reduction of dose rates over the following years is then set by the rate of radioactive decay alone as the majority of the radiocesium has become fixed to the soil matrix.
King, G.*; Sueoka, Shigeru; Ahadi, F.*; Gautheron, C.*; Herman, F.*; Tagami, Takahiro*; Tsukamoto, Sumiko*
no journal, ,
no abstracts in English
Takayasu, Kentaro; Takeuchi, Ryuji; Onoe, Hironori
no journal, ,
The Groundwater REcovery Experiment in Tunnel (GREET) is conducted by making the Closure Test Drift (CTD) recovered with water at the depth of 500m. Backfilling test is conducted as a part of GREET to acquire physical property change of the backfill material. Bentonite mixture was constructed into two pits excavated 1m in depth on the floor of the CTD. Hydraulic pressure, soil pressure and moisture content were measured to grasp the groundwater saturation process and the swelling process of backfill material. The moisture content in the pits got almost fully saturated till one month after. During water filling event, both hydraulic pressure and soil pressure reached 3.1 MPa at maximum. The swelling pressure of the backfill was calculated as 0.03-0.09 MPa. Observation inside the pit will be continued, and characteristics of backfill material will be investigated again. Changes of hydraulic pressure and soil pressure will be simulated and the construction method will be validated.
Fukuda, Shoma*; Sueoka, Shigeru; Hasebe, Noriko*; Tamura, Akihiro*; Arai, Shoji*; Tagami, Takahiro*
no journal, ,
no abstracts in English
Satou, Yukihiko; Minowa, Haruka*; 45 of others*
no journal, ,
no abstracts in English