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Nakashima, Yosuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Oki, Kensuke*; Sakamoto, Mizuki*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; Imai, Tsuyoshi*; et al.
Journal of Nuclear Materials, 463, p.537 - 540, 2015/08
Times Cited Count：19 Percentile：82.55(Materials Science, Multidisciplinary)Nakashima, Yosuke*; Sakamoto, Mizuki*; Yoshikawa, Masayuki*; Oki, Kensuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; et al.
Proceedings of 25th IAEA Fusion Energy Conference (FEC 2014) (CD-ROM), 8 Pages, 2014/10
Yoshida, Hidekazu*; Metcalfe, R.*; Ishibashi, Masayuki; Minami, Masayo*
Geofluids, 13(1), p.45 - 55, 2013/02
Times Cited Count：14 Percentile：55.31(Geochemistry & Geophysics)In granitic rocks fracture networks provide pathways for groundwater flow and solute transport that need to be understood to assess the long-term performance of deep underground environment. In order to clarify the long-term processes, Japanese plutons of different ages were studied. Detailed investigation of in-situ fracture fillings sampled from a depth of 300 meters was carried out to clarify the fracturing and mineral infilling processes. Different plutons show identical episodes, consisting of: brittle tensile fracturing (Stage I); relatively rapid uplifting accompanied by hydrothermal water circulation that produced fracture fillings (Stage II); and a period of low-temperature meteoric water circulation (Stage III). The paragenesis of carbon isotopic compositions of carbonate minerals show that there were distinct episodes of mineral precipitation. The evolution of fillings identified here enable development of a model of fracturing and persistence of fluid conducting systems.
Aoki, Kenji*; Mito, Yoshitada*; Minami, Masayuki*; Matsui, Hiroya; Niunoya, Sumio*
JAEA-Research 2007-077, 126 Pages, 2007/09
JAEA-Research-2007-077.pdf:16.68MB
To understand the size and state of EDZ is one of the problems in the technological development for geological disposal of HLW. AE which is measured directly and evaluate EDZ is paid to attention inside and outside the country, and the utility is reported for the crystalline rock. However, there are few cases to measure AE in sedimentary soft rocks because of the difficulty to acknowledge a few AE waves with small energy. The author consulted AE properties of Horonobe siliceous rocks from laboratory tests and evaluated size and state of EDZ from numerical analysis.
Mito, Yoshitada*; Chang, C. S.*; Aoki, Kenji*; Matsui, Hiroya; Niunoya, Sumio; Minami, Masayuki*
Proceedings of 11th Congress of the International Society for Rock Mechanics (ISRM 2007), Vol.1, p.273 - 276, 2007/08
In order to examine the relationship between AE, stress change and rock failure, the authors conducted the high stiffness triaxial compression tests including AE measurements, and its simulations by DEM (Distinct Element Method) using the bonded particle model. As the result, it is clarified that predominant AE frequency is a significant AE parameters to monitor the stress change in fracturing process of soft sedimentary rocks. After that, the DEM simulation of the triaxial compression test using the bonded particles model is conducted to visualize the fracturing process in the rock specimen. As the results, the relationship between AE, stress change and rock failure is clarified. Furthermore the three-dimensional DEM simulation under the in-situ stress condition provides a successful result to examine the borehole breakout observed in the actual deep borehole in the soft sedimentary rock, and the applicability of the simulation to the actual field is verified.
Aoki, Kenji*; Mito, Yoshitada*; Kurokawa, Susumu*; Matsui, Hiroya; Niunoya, Sumio; Minami, Masayuki*
Dai-36-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu, p.235 - 238, 2007/01
The monitoring of EDZ (Excavation Disturbed Zone) is one of the most important required technologies for the design of rock caverns such as the high-level radioactive waste repository. The authors developed the stress-based evaluation system of EDZ by AE monitoring and DEM (Distinct Element Method) simulation. In order to apply this system to the soft rock site, the authors try to grasp the relationship between AE parameters, stress change and rock failure by performing the high stiffness tri-axial compression tests including AE measurements on the soft rock samples, and its simulations by DEM using bonded particle model.
Suzuki, Yoshio; Minami, Takahiro; Tani, Masayuki; Nakajima, Norihiro; Keller, R.*; Beisel, T.*
Proceedings of 7th International Meeting on High Performance Computing for Computational Science (VECPAR '06)/Workshop on Computational Grids and Clusters (WCGC '06) (CD-ROM), 9 Pages, 2006/07
The interoperability among different science grid systems is indispensable to worldwide use of a large-scale experimental facility as well as a large-scale supercomputer. One of the simplest ways to achieve the interoperability is to convert messages among different science grid systems without modifying themselves. Under such consideration, the interoperability between UNICORE and ITBL (IT-Based Laboratory) has been achieved with hardly modifying these grid systems by adopting a connection server which works as a mediator. Until international standardization is established, the method of message conversion among different science grid systems is promising as a way to establish the interoperability.
Minami, Takahiro; Matsubara, Hitoshi; Yamagishi, Nobuhiro; Hasegawa, Yukihiro; Aoyagi, Tetsuo; Nakajima, Norihiro; Tani, Masayuki
no journal, ,
no abstracts in English
Matsubara, Hitoshi; Minami, Takahiro; Hazama, Osamu; Nishida, Akemi; Tian, R.; Nakajima, Norihiro; Tani, Masayuki
no journal, ,
A nuclear power plant is made up of numerous components. In previous techniques, structural analyses of entire nuclear power plant have not been achieved because it is assumed to be united structure. In this work, through our new model approach called the assembled-structure analysis, simulation of an entire nuclear power plant by assembling of individual components was made possible.
Suzuki, Yoshio; Kushida, Noriyuki; Yamagishi, Nobuhiro; Minami, Takahiro; Matsumoto, Nobuko; Nakajima, Kohei; Nishida, Akemi; Matsubara, Hitoshi; Tian, R.; Hazama, Osamu; et al.
no journal, ,
no abstracts in English
Kushida, Noriyuki; Suzuki, Yoshio; Minami, Takahiro; Tani, Masayuki; Nakajima, Norihiro; Keller, R.*; Beisel, T.*
no journal, ,
no abstracts in English
Otosaka, Shigeyoshi; Oku, Shunsuke*; Minami, Hideki*; Minakawa, Masayuki*; Noriki, Shinichiro*
no journal, ,
The Japan Sea is regarded as a miniature of the ocean because of its bowl-like topography and unique seawater circulation. Recent studies have suggested that biogeochemical processes in the Japan Sea correspond with the global climate change. In this study, we assessed decadal changes in particulate flux and elemental composition of sinking particle in the Japan Sea by comparing results of a sediment trap experiment in September 1984 with those in 1999-2001. Total mass flux did not show remarkable temporal change, however, biogenic opal/carbonate ratios observed recently were lower than those from the previous observation. In addition, relative content of scavenging elements such as manganese and cobalt also showed a decrease between the 15 years. These results may indicate decadal changes in ecological characteristics at the surface and transport processes of particulate materials in the deep water.
Otosaka, Shigeyoshi; Oku, Shunsuke*; Minami, Hideki*; Minakawa, Masayuki*; Noriki, Shinichiro*
no journal, ,
Many researchers pointed out that decadal change in deep-sea circulation in the Japan Sea are strongly related with the global climate change. However, little is known about changes in fluxes and elemental composition of sinking particles in the sea. In this study, we assessed temporal changes in elemental composition of sinking particle in the Japan Sea by comparing results of a sediment trap experiment in middle 1980s with those in end of 1990s. The result indicated that (1) the contribution of Asian dust in sinking particles decreased significantly, (2) horizontal transport of re-suspended particles from the slope regions was weakened, and (3) there was no significant increase in vertical transport of anthropogenic heavy metals to the interior of the Japan Sea.
Oku, Shunsuke*; Otosaka, Shigeyoshi; Minakawa, Masayuki*; Minami, Hideki*; Noriki, Shinichiro*
no journal, ,
Autochthonous Ba (Ba-xs) in seawater is enriched in particulate materials by marine biota and settles down to the seabed. Therefore, Ba-xs is known as a proxy of export production in the surface ocean. However, it is necessary to discuss the effect of lateral transport of Ba-xs for the accurate estimation of the export flux. In this study, the authors investigated the effect of lateral transport of Mn-xs from a sediment trap experiment in the Japan Sea. Particulate fluxes of Ba-xs showed a positive relationship between flux of autochthonous Mn (Mn-xs). The flux of Mn-xs was higher in winter and it might be caused by the lateral transport of particulate materials from the shelf regions. The results indicated that Ba-xs is transported laterally and the effect was on a par with the sinking of biogenic particles.
Nakashima, Yosuke*; Ichimura, Kazuya*; Takeda, Hisahito*; Iwamoto, Miki*; Hosoda, Yasunari*; Shimizu, Keita*; Oki, Kensuke*; Sakamoto, Mizuki*; Ono, Noriyasu*; Kado, Shinichiro*; et al.
no journal, ,
no abstracts in English
