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Takai, Shizuka; Kimura, Hideo*; Uchikoshi, Emiko*; Munakata, Masahiro; Takeda, Seiji
JAEA-Data/Code 2020-007, 174 Pages, 2020/09
JAEA-Data-Code-2020-007.pdf:4.23MB
The MIG2DF computer code is a computer program that simulates groundwater flow and radionuclide transport in porous media for the safety assessment of radioactive waste disposal. The original version of MIG2DF was released in 1992. The original code employs a two-dimensional (vertical or horizontal cross-section, or an axisymmetric configuration) finite-element method to approximate the governing equations for density-dependent saturated-unsaturated groundwater flow and radionuclide transport. Meanwhile, for geological disposal of radioactive wastes, landscape evolution such as uplift and erosion needs to be assessed as a long-term geological and climate events, considering site conditions. In coastal areas, the impact to groundwater flow by change of salinity distribution to sea level change also needs to be considered. To deal with these events in the assessment, we have revised the original version of MIG2DF and developed the external program which enables MIG2DF to consider unsteady landscape evolution. In these developments, this report describes an upgrade of MIG2DF (Version 2) and presents the configuration, equations, methods, and verification. This reports also give the explanation external programs of MIG2DF: PASS-TRAC (the particle tracking code), PASS-PRE (the code for dataset preparation), and PASS-POST (the post-processing visualization system).
Ishizawa, Akihiro*; Idomura, Yasuhiro; Imadera, Kenji*; Kasuya, Naohiro*; Kanno, Ryutaro*; Satake, Shinsuke*; Tatsuno, Tomoya*; Nakata, Motoki*; Nunami, Masanori*; Maeyama, Shinya*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 92(3), p.157 - 210, 2016/03
The high-performance computer system Helios which is located at The Computational Simulation Centre (CSC) in The International Fusion Energy Research Centre (IFERC) started its operation in January 2012 under the Broader Approach (BA) agreement between Japan and the EU. The Helios system has been used for magnetised fusion related simulation studies in the EU and Japan and has kept high average usage rate. As a result, the Helios system has contributed to many research products in a wide range of research areas from core plasma physics to reactor material and reactor engineering. This project review gives a short catalogue of domestic simulation research projects. First, we outline the IFERC-CSC project. After that, shown are objectives of the research projects, numerical schemes used in simulation codes, obtained results and necessary computations in future.
Watanabe, Tomohiko*; Idomura, Yasuhiro; Maeyama, Shinya; Nakata, Motoki; Sugama, Hideo*; Nunami, Masanori*; Ishizawa, Akihiro*
Journal of Physics; Conference Series, 510, p.012045_1 - 012045_11, 2014/05
Times Cited Count：2 Percentile：66.32(Computer Science, Interdisciplinary Applications)Plasma turbulence accompanied with fluctuations of the distribution function and the electromagnetic fields develops on the phase space composed of the configuration space and the velocity space. Detailed structures of the distribution function in magnetic fusion plasmas are investigated by means of gyrokinetic simulations performed on massively parallel supercomputers. The gyrokinetic simulations of drift wave turbulence have demonstrated entropy transfer in the phase space, zonal flow enhancement by helical fields and the resultant transport reduction. The state-of-the-art high performance computing is utilized for a multi- scale turbulence simulation covering ion- and electron-scales and for a global-scale simulation of turbulent transport in a sub-ITER sized plasma.
Sakai, Ryutaro; Takeda, Seiji; Munakata, Masahiro; Kimura, Hideo
JAEA-Research 2013-006, 18 Pages, 2013/07
JAEA-Research-2013-006.pdf:2.77MB
In the safety assessment for a geological disposal of radioactive waste, it is important to establish validation methods for deep groundwater flow to estimate radionuclide migration to human environment through groundwater flow. Costal sedimentary rocks in our country provide dominant fossil water formed during sub-seabed sedimentation and chemical compositions of the water mixed with meteoric water and fossil water depend on the initial fossil water composition and groundwater flow conditions. Analytical study on the effects of groundwater flow on the mixed water quality as a indicator of its Cl/
O ratios was carried out in case of Horonobe district, where geochemical data is now being stored.
Takeda, Seiji; Nishimura, Yuki; Munakata, Masahiro; Sawaguchi, Takuma; Kimura, Hideo
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 19(2), p.23 - 38, 2012/12
In safety assessments of the geological disposal of TRU waste, it is important to understand the possibility and extents of influence of hyperalkaline groundwater derived from the degradation of cementitious materials that are used as forms for the containment of waste and as constructional materials in the disposal facilities of TRU waste. In this research, reactive transport analyses of hyperalkaline plume induced by cementitious materials were performed to clarify the extent of the hyperalkaline groundwater spreading and the type of alterations occurring with or without considering the precipitation of zeolite. The effect of the groundwater velocities on the spread of hyperalkaline groundwater was also examined. The analysis results indicate that whether zeolites precipitate or not significantly affect extent of hyperalkaline groundwater and the amount of precipitation of secondary minerals. In the case that groundwater velocity was 10 times higher, hyperalkaline groundwater spread broader than the original groundwater velocity case. It might be due to our kinetic dissolution model of host rock minerals, which limits chemical reactions neutralizing hyperalkaline groundwater.
Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo
JAEA-Research 2011-054, 19 Pages, 2012/03
JAEA-Research-2011-054.pdf:2.07MB
In the safety assessment for a geological disposal of radioactive waste, it is important to establish validation methods for deep groundwater flow system to estimate radionuclide migration to human environment through groundwater flow. This study discussed the method which estimates groundwater mixing condition and groundwater flow process using principal component analysis (PCA) to groundwater chemistry and isotopic compositions, together with data of groundwater age and trace element in case of Horonobe area. The results show that hydrochemical system can be divided into two systems: (1) three deep groundwater mixing system at depths greater than 200 to 400 m, (2) mixing area of deep groundwater and surface water at depths less than 200 to 400 m. Groundwater in the deep aquifer is suggested to be discharged at surface through Omagari Fault.
Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo; Ooka, Masao*; Seguchi, Mariko*
JAEA-Research 2011-029, 24 Pages, 2011/11
JAEA-Research-2011-029.pdf:3.67MB
In the safety assessment for a geological disposal of radioactive waste, it is important to establish validation methods for regional groundwater flow system to estimate radionuclide migration to human environment through groundwater flow. It is necessary to validate the groundwater flow property and flow boundary, as multi-groundwater systems including the different groundwater origins are possible to exist at deep underground. This results show that mixing analysis based on hydrochemical data and spatial plotting with hydrochemical data and thermal data are applicable to validate groundwater flow pattern and groundwater flow boundary in case of Horonobe area. It also demonstrates that mixing analysis based on hydrochemical data and spatial plotting with hydrological and hydrochemical data are applicable to validate the groundwater flow property and groundwater flow boundary in case of Nagaoka area.
Hanatani, Ikuo; Munakata, Masahiro; Kimura, Hideo; Sanga, Tomoji*
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 18(1), p.3 - 23, 2011/06
Evaluation of the radionuclide migration toward the human environment associated with groundwater flow is an issue of importance in safety assessment of geological disposal. We constructed models depicting the influences of geomorphological evolution on long-term groundwater flow. This was done by reconstructing the processes of river deepening with historical simulation of the profiles of four rivers in the Boso Peninsula. The study resulted in the sum of erosion during the past 125,000 years which is the equivalent of one glacial to interglacial cycle. The profiles of four rivers during the last glacial age to the present were successfully reconstructed using similar parameters. It was found that the profiles were sculpted in accordance with the uplifting rates with very little influence of initial topography owing to the relatively soft and easily dissected characteristics of the geological units.
Ikeda, Makoto; Munakata, Masahiro; Sakai, Ryutaro; Kimura, Hideo; Jia, H.*; Matsuba, Hisashi*
Nihon Chikasui Gakkai 2011-Nen Shunki Koenkai Koen Yoshi, p.86 - 91, 2011/05
no abstracts in English
Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo; Ichikawa, Yasuo*; Nakamura, Masaru*
JAEA-Research 2010-066, 20 Pages, 2011/03
JAEA-Research-2010-066.pdf:2.26MB
In the safety assessment for a geological disposal of radioactive waste, it is important to establish modelling methods and validation methods for regional groundwater flow system in the depth of 300
1000m to estimate radionuclide migration to human environment through groundwater flow system. The study discussed application of data and assessment methods for model validation based on multiple indicators such as hydrology, groundwater chemistry, temperature and age of groundwater in case of the Boso Peninsula in Chiba Prefecture where a lot of in-situ data about groundwater was measured. This results show that existing hydrochemical and thermal data are applicable to explain freshwater and saltwater distribution and groundwater flow pattern in case of regional scale. It also indicates that gravitational groundwater is likely to flow into the deep part of fresh-saltwater interface based on the exist of Na-HCO
type water above fresh-saltwater interface mixed with meteoric water and that multiple indicators are applicable to evaluate groundwater flow property and groundwater flow boundary in case of site scale region.
Munakata, Masahiro; Matsusue, Kazuyuki; Hisada, Kimikazu; Kimura, Hideo
Iwa No Rikigaku Nyusu, (98), p.17 - 20, 2011/01
A purpose of this research is to develop a safety assessment code for groundwater flow in geological disposal though the validation study performed in the Horonobe URL site. SAB-2 borehole is depth of 710 m. Pressure and temperature measurements and hydraulic investigations are performed in the SAB-2 borehole and planned in another boreholes. We have a research plan to compare the observed data and analyzed results by using developing code for groundwater flow.
Hanatani, Ikuo; Munakata, Masahiro; Kimura, Hideo; Sanga, Tomoji*
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 17(2), p.55 - 70, 2010/12
We conducted a study on key factors regarding changes of groundwater flow from the last glacial to the postglacial stages in the Horonobe. Specifically, geomorphological analysis was carried out using aerial photographs and a high resolution (10 m) DEM to obtain the distribution of the slopes that had been formed after the last glacial stage, and the erosion depth of those slopes was analyzed. The results are summarized as follows: (1) Although periglacial smooth slopes which expanded widely in Horonobe region over the last glacial stage were eroded by rainfall increase and steeper slopes had been formed in the postglacial stage, this postglacial erosion is not uniform and is strongly influenced by the geology. (2) The drainage density is low and less than 40% of periglacial smooth slopes have been eroded to the present in the Koetoi and Wakkanai Formations while it is high and 60% or more of those slopes have already been eroded in the Yuchi and Sarabetsu Formations.
Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo; Ooka, Masao*; Kameya, Hiroshi*; Hosoda, Koichi*
Dai-21-Kai Zenkoku Chishitsu Chosagyo Kyokai Rengokai "Gijutsu Fuoramu" Koenshu (CD-ROM), 2 Pages, 2010/11
no abstracts in English
Ikeda, Makoto; Munakata, Masahiro; Sakai, Ryutaro; Fuchiwaki, Hirotaka; Kimura, Hideo; Matsuba, Hisashi*
Nihon Chikasui Gakkai 2010-Nen Shuki Koenkai Koen Yoshi, p.282 - 287, 2010/11
no abstracts in English
Takeda, Seiji; Yamaguchi, Tetsuji; Nagasawa, Hirokazu; Watanabe, Masatoshi; Sekioka, Yasushi; Kanzaki, Yutaka; Sasaki, Toshihisa; Ochiai, Toru; Munakata, Masahiro; Tanaka, Tadao; et al.
JAEA-Research 2009-034, 239 Pages, 2009/11
JAEA-Research-2009-034.pdf:33.52MB
In safety assessment for geological disposal of high level radioactive waste, it is of consequence to estimate the uncertainties due to the long-term frame associated with long-lived radionuclides and the expanded geological environment. The uncertainties result from heterogeneity intrinsic to engineered and natural barrier materials, insufficient understanding of phenomena occurring in the disposal system, erroneous method of measurement, and incomplete construction. It is possible to quantify or to reduce the uncertainties according to scientific and technological progress. We applied a deterministic and a Monte Carlo-based probabilistic method simulation techniques to the uncertainty analysis for performance of hypothetical geological disposal system for high level radioactive waste. This study provides the method to evaluate the effects of the uncertainties with respect to scenarios, models and parameters in engineering barrier system on radiological consequence. The results also help us to specify prioritized models and parameters to be further studied for long-term safety assessment.
Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo
Chikasui Gakkai-Shi, 51(4), p.311 - 329, 2009/11
In order to evaluate the regional groundwater flow system, the author has investigated stream flow of 3 rivers and analyzed flow rates and chemical compositions, isotopic ratios of hydrogen and oxygen of water samples collected from wells, rivers and springs in the feeder streams area in the Yoro river basin, in Chiba Prefecture. As a result of this study, (Na)Ca-HCO type water is evaluated to be recharged from the highly permeable sand-dominant domain (Daifuku Mt.). In addition, it is estimated that the groundwater flow preferentially in direction of strike and discharge at the middle and downstream domain as Ca-HCO type water, and partially pass through fractures of low permeable alteration layer up to the surface area as evolved Na-HCO type water.
Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo
JAEA-Research 2008-122, 18 Pages, 2009/03
JAEA-Research-2008-122.pdf:6.57MB
It is important to evaluate effect on the groundwater flow system by the natural phenomena in the safety assessment of geological disposal of radioactive waste through a survey of recent scientific informations. In this report we study about the scenario of sea level change effecting on the groundwater flow system which is very important for a safety of disposal facility in costal area. As a result, this study show that the non-current paleo-fresh water at present is possible to start to discharge at sea floor in the next glacial period by denudation of marine-clay sediments and to grow stagnant again in the next interglacial period by deposition of marine-clay sediments. Therefore it is important to predict the scenario considering the denudation and deposition correlated with transgression and regression that could affect the change of groundwater flow characteristics during the glacial and interglacial period.
Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo
JAEA-Research 2007-083, 38 Pages, 2008/01
JAEA-Research-2007-083.pdf:3.29MB
Japan Atomic Energy Agency has investigated a sedimentary rock area in the central part of Yoro river basin, in Chiba Prefecture for verification of analytical groundwater flow model. For the purpose of establishing a methodology for evaluation of regional groundwater flow system, investigations of flow rates, chemical compositions and isotope ratios for water samples collected from wells, rivers and springs were carried out. As a result, considerable amount of ground water which is NaCa-HCO type or evolved Ca-HCO type meteoric origin cultivated at the high permeable sand dominant layer preferentially flows toward its strike direction discharging at the downstream region of river. The evolved Ca-HCO type or Na-HCO type ground water with long residence time was inferred to form different flowpath toward the dipping direction of bedrock more than 100m at depth and to upwell to the downstream region of Urajiro River as a feeder of Yoro River through the low permeable mud layer.
Yamakawa, Tadashi; Munakata, Masahiro; Kimura, Hideo; Hyodo, Hiroshi*
JAEA-Research 2007-039, 26 Pages, 2007/03
JAEA-Research-2007-039.pdf:4.68MB
Radionuclide migration toward human society through geologic processes is to be assessed as part of long-term safety assessments of geologic disposal for radioactive waste. This study was conducted to develop methodologies of boundary delineation for regional groundwater flow system. Geographic Information System, GIS, was applied to Miyakoji in the Abukuma as an area of interest. The present study revealed that, taking the groundwater flows and fracture characteristics of the area into consideration, the groundwater flow system in Miyakoji drainage basin should be bounded by the Otakine mountain area and the northern part of Tokoha drainage basin, which occupies a larger area than understood before.
Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo
JAEA-Research 2006-084, 16 Pages, 2007/01
JAEA-Research-2006-084.pdf:1.74MB
Japan Atomic Energy Agency (JAEA) has started to investigate a sedimentary rock area in the Yoro river basin, in Chiba Prefecture. Hydro-chemical conditions of the regional groundwater were discussed based on temperature, chemical compositions, isotopic ratios of hydrogen and oxygen, and the isotopic age of radioactive carbon for water samples collected from wells, rivers and springs in the Yoro river basin. It was found that the groundwater system in this basin consists of types of water: Ca-HCO type water, Na-HCO type water and NaCl type water. The Ca-HCO type water is meteoric water cultivated several thousand years or after, the Na-HCO type water is meteoric water cultivated under cold climates several to twenty thousand years ago. The NaCl type water is fossil brine water formed twenty thousand years ago. It was also observed that the Na-HCO type water upwelled at the surface originates from GL-200m to -400m.
