Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Ishibashi, Masayuki; Ando, Tomomi*; Sasao, Eiji; Yuguchi, Takashi; Nishimoto, Shoji*; Yoshida, Hidekazu*
Oyo Chishitsu, 55(4), p.156 - 165, 2014/10
Understanding of long-term history of water-conducting features such as flow-path fractures is key issue to evaluate deep geological environment for geological disposal of high-level radioactive waste (HLW). Thus, we conducted study on the geological features and the long-term behavior of flow-path fractures based on the data obtained at -300m levels in the Mizunami Underground research laboratory (MIU), central Japan. Total 1670 fractures were mapped in underground gallery at the -300m levels. Flow-path fractures occupy about 11% of all fractures. The flow-path fractures are divided into grout filling fractures and low inflow-rate fractures. All of the grout filling fractures is filled with calcite as fracture filling minerals without conspicuous host rock alteration around fractures. The low inflow-rate fractures possessed similar geological character with the sealed fractures which are not acted as flow-path. The geological character of fracture filling and host tock alteration around fractures indicates the history of the formation at the time of intrusion and emplacement of host granite (Stage I), then filling at hydrothermal event (Stage II), and finally opening and elongation during exhumation stage (Stage III). In conclusion, the present flow-path fractures were formed by opening and/or elongation of pre-existed fractures, which were filled at the hydrothermal event, at the time of exhumation.
Nakajima, Makoto*; Seno, Shoji*; Onoe, Hironori; Ishibashi, Masayuki; Saegusa, Hiromitsu; Sawada, Atsushi
Dai-42-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.107 - 112, 2014/01
Japan Atomic Energy Agency is proceeding with the Mizunami Underground Research Laboratory Project in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock for geological disposal of high level radioactive wastes. We have carried out discrete fracture network modeling, groundwater flow and particle tracking simulation in order to understand the important factors for the solute transport characterizations. In this paper, a method for estimating hydraulic parameter of discrete fracture network model based on in-situ data at underground gallery are described.
-
systemsSeo, Hitoshi; Ishibashi, Shoji*; Okano, Yoshinori*; Kobayashi, Hayao*; Kobayashi, Akiko*; Fukuyama, Hidetoshi*; Terakura, Kiyoyuki*
Journal of the Physical Society of Japan, 77(2), p.023714_1 - 023714_4, 2008/02
Times Cited Count：34 Percentile：79.78(Physics, Multidisciplinary)Electronic states of single-component molecular metals M(tmdt)
(M=Ni,Au) are studied theoretically. We construct an effective three-band Hubbard model for each material by numerical fitting to first-principles band calculations, while referring to molecular orbital calculations for the isolated molecules. The model consists of two kinds of base orbital for each molecule with hybridization between them, i.e., a -character orbital for each of the two tmdt ligands, and, a pd-orbital for M=Ni or a pd
-orbital for M=Au centered on the metal site; this indicates that these materials can be considered as novel multiband -d systems. We find that both orbitals contribute to realize the metallic character in Ni(tmdt). The origin of the antiferromagnetic transition observed in Au(tmdt) is also discussed based on this model.
Kiyanagi, Yoshiaki*; Nagamiya, Shoji*; Oyama, Yukio; Ikeda, Yujiro; Oigawa, Hiroyuki; Igashira, Masayuki*; Baba, Mamoru*; Iwasaki, Tomohiko*; Watanabe, Yukinobu*; Ishibashi, Kenji*
Nihon Genshiryoku Gakkai-Shi, 46(3), p.173 - 197, 2004/03
no abstracts in English
and Au(tmdt)Seo, Hitoshi; Okano, Yoshinori*; Ishibashi, Shoji*; Kobayashi, Hayao*; Fukuyama, Hidetoshi*; Kobayashi, Akiko*
no journal, ,
We investigate the electronic states of single component molecular conductors Ni(tmdt) and Au(tmdt). Starting from the intramolecular bonding/antibonding molecular orbitals which contributes to the levels near the Fermi energy, we contstruct an effective tight-binding model by decomposing them into orbitals of two (tmdt) and that of the metal. We discuss possible spin/charge ordered states within mean-field approximation and compare our results with the magnetic order found in Au(tmdt).
-A
VO
(A=Na, Sr)Seo, Hitoshi; Ishibashi, Shoji*
no journal, ,
Electronic properties of -AVO (A=Na, Sr) are investigated theoretically. By calculating their band structures within GGA first-principles method and deriving effective tight-binding models by numerical fitting to them, we find that their electronic state is composed of two different two-leg ladders which are coupled three-dimensionally, with average of 1/6 electron per V site for A=Na and 1/3 electron per V site for A=Sr, consistent with previous studies. We investigate the mechanism of novel charge ordering patterns observed in these compounds, and that of spin ordering in the Na compound and the spin gap formation in the Sr compound, by introducing on-site Coulomb interaction into the tight-binding models, i.e., considering Hubbard models. Effects of cation ordering, which is found to affect the physical properties in the metallic phases of both compounds, are also discussed.
Ishibashi, Masayuki; Tsuruta, Tadahiko; Yuguchi, Takashi; Nishimoto, Shoji*; Sasao, Eiji; Yoshida, Hidekazu*
no journal, ,
no abstracts in English
Hosoya, Shinichi*; Seno, Shoji*; Nakajima, Makoto*; Atsumi, Hiroyuki*; Ishibashi, Masayuki; Morikawa, Keita; Onoe, Hironori; Kunimaru, Takanori
no journal, ,
Discrete Fracture Network (DFN) model provides the basis of groundwater flow analysis and solute transport analysis for crystalline rock. Due to its complexity, it is difficult to estimate how the input parameters influence the result of the analysis. In this study, using the data obtained in the Mizunami Underground Research Laboratory (MIU) project conducted by Japan Atomic Energy Agency (JAEA), we examined how the modeling methodology influenced the result of groundwater flow analysis and solute transport analysis.
Ishibashi, Masayuki; Sasao, Eiji; Nakajima, Makoto*; Atsumi, Hiroyuki*; Onoe, Hironori; Saegusa, Hiromitsu; Kawabata, Junichi*; Masumoto, Kazuhiko*; Seno, Shoji*; Iwano, Keita*
no journal, ,
no abstracts in English
Atsumi, Hiroyuki*; Nakajima, Makoto*; Iwano, Keita*; Masumoto, Kazuhiko*; Seno, Shoji*; Kawabata, Junichi*; Ishibashi, Masayuki; Sasao, Eiji; Hosoya, Shinichi*
no journal, ,
no abstracts in English
