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Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo; Ooka, Masao*; Kameya, Hiroshi*
no journal, ,
In the safety assessment for a geological disposal of radioactive waste, it is important to develop a methodology and uncertainties of long-term estimation of regional groundwater flow system. The authors discussed the uncertainties of hydraulic conductivity as a significant hydrological parameter for regional groundwater flow analysis model. This study demonstrated that confining pressure change cased by uplift and subsidence and change of hydraulic gradients under the long-term geological and hydrological environmental change could possibly produce variations more than one order of magnitude in hydraulic conductivity of rock mass. It also clarified that the effect of water quality change on hydraulic conductivity is not negligible and that the replacement of fresh water and saline water cased by sea level change could predict to reduce hydraulic conductivities in rock mass 0.6 times from its present data in case of Horonobe site.
Matsumoto, Kazuhiro; Saito, Yuya; Tanai, Kenji
no journal, ,
no abstracts in English
Nakayama, Masashi; Sato, Haruo; Ito, Seiji
no journal, ,
High level radioactive waste repository will be constructed using a variety of concrete such as shotcrete, lining for rock support. It is anticipated that highly alkaline plume released from the cement hydrates could influence the long-term performance of barrier system as a result of degradation of the buffer material and rock. In order to reduce hyper alkaline, JAEA is now undertaking development of low alkaline cement (HFSC: Highly Fly ash contained Silicafume Cement).
Koo, Shigeru*; Ebashi, Takeshi; Inagaki, Manabu
no journal, ,
no abstracts in English
Itazu, Toru; Kato, Tomoko; Inagaki, Manabu; Suzuki, Yuji*
no journal, ,
The project of high-level radioactive waste disposal is in the stage of site selection in Japan, and the site-specific performance assessment using the methodology of site-generic study has been developed after the publication of the second progress report (H12). Japan Atomic Energy Agency (JAEA) has started the biosphere assessment using the behavior of radionuclides, which depends on the site-specific geological condition. In this presentation, we report the examination of biosphere assessment methodology in view of surface and near-surface environment.
Ebashi, Takeshi; Kawamura, Makoto; Inagaki, Manabu; Shibata, Masahiro; Chiba, Tamotsu*
no journal, ,
no abstracts in English
Yamamoto, Yoichi; Maekawa, Keisuke; Yokota, Hideharu
no journal, ,
Horonobe Underground Research Center of Japan Atomic Energy Agency has carried out investigated surface hydrological investigation in and around the Horonobe Underground Research Laboratory (URL) area as a part of Horonobe URL project. We continue meteorological observation, observation of river flux and water quality, soil moisture observation and groundwater level observation in order to understand recharge rate and groundwater flow in the shallow part, which are required for the setting of boundary and initial condition of the groundwater flow analysis. Outline of the surface hydrological investigation and some study results of groundwater flow around surface are reported.
Ijiri, Yuji*; Hatsuyama, Yoshihiro*; Nago, Makito*; Sato, Masaru*; Sanoki, Satoru*; Kunimaru, Takanori; Sugita, Yutaka
no journal, ,
no abstracts in English
Munakata, Masahiro; Kimura, Hideo; Sakai, Ryutaro; Namekawa, Maki; Fuchiwaki, Hirotaka
no journal, ,
no abstracts in English
Semba, Takeshi; Miyamoto, Tetsuo; Yabuuchi, Satoshi; Matsuoka, Toshiyuki; Asamori, Koichi; Yamanaka, Yoshiaki*
no journal, ,
no abstracts in English
Abe, Hironobu; Shimoyama, Tadashi; Yamasaki, Masanao*; Sanoki, Satoru*
no journal, ,
no abstracts in English
Sugita, Yutaka; Nakamura, Takahiro; Sanada, Hiroyuki; Kunimaru, Takanori
no journal, ,
no abstracts in English
Sato, Haruo
no journal, ,
Swelling pressure versus Na-montmorillonite partial density was estimated for solutions with various salinities (NaCl solutions, artificial saline water, Horonobe groundwater) based on the thermodynamic data of the interlayer water of Na-montmorillonite and of water in the solutions of various salinities coming in contact with the montmorillonite and compared to data measured under the same salinities for various kinds and different silica sand contents of bentonites. The calculated swelling pressures decreased with increasing salinity. This is in good agreement with the fact that the swelling pressure of bentonite generally decreases with increasing salinity. Since all measurements were carried out under the conditions that the soluble minerals remain being contained, all the measured data are considered to contain the effect of the increase of the ionic strength of porewater by dissolution of the soluble minerals, and the calculated values were within the range of the scattering in the measured data. By this model, swelling pressures for various Na-montmorillonite contents and silica sand contents of bentonites saturated with solutions of various salinities can be calculated as a function of dry density of the bentonites. Furthermore, analyses for THMC coupled processes can be also carried out by considering those enthalpy and entropy data.
Shimoda, Satoko*; Saito, Hironori*; Takase, Toshio*; Yamaguchi, Kohei; Oda, Chie; Honda, Akira
no journal, ,
The unstable primary mineral is dissolved and the precipitation of a steadier secondary mineral happens thermodynamically when a high alkaline groundwater of the cement system material origin is infiltrated from the radioactive waste geological disposal facilities to a peripheral bedrock. Therefore, the pore structure of the hostrock changes by the precipitation and dissolution, and the material transportation characteristic of the bedrock changes. It is necessary to decide the chemical reaction scheme for the analysis. However, the combination of the secondary minerals exists innumerably. Therefore, granite was assumed to be an example by summarizing the chemical reaction scheme in the mineral alteration scenario, and the mineral alteration scenario concerning the reaction with a high pH groundwater was presented. It dealt with the uncertainty concerning the mineral alteration by preparing two or more scenarios with a different alteration route.
Motoshima, Takayuki*; Ijiri, Yuji*; Saegusa, Hiromitsu
no journal, ,
no abstracts in English
Hatanaka, Koichiro
no journal, ,
Horonobe URL project is a research and development program with construction of underground facilities for sedimentary rock and saline groundwater distributing over the Horonobe Town area. The goal of the Horonobe URL project is to develop the basis for the technologies of investigation/analysis/evaluation, to develop the basis of engineering technology in the deep underground, and to confirm the applicability of disposal technologies in the actual geological environment. In addition, JAEA Horonobe has been observing the agreement concluded among Hokkaido prefecture, Horonobe Town and JNC (current JAEA) in November, 2000, in carrying out the research and development in the Horonobe Town area.
Tsusaka, Kimikazu; Yamasaki, Masanao*; Inagaki, Daisuke
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no abstracts in English
Suzuki, Yoshinori; Onuki, Toshihiko
no journal, ,
We examined flavin mononucleotide mediated reduction of U(VI)-citrate complex. The CV of FMN at pH 6.0 showed a couple of clear redox peaks at -0.36 V (vs. Ag/AgCl). Addition of U(VI) into the solution made the reduction peak current increased and the oxidation peak current decreased. The reduction peak current increased with an increase of the U(VI) concentration. These results indicate that FMN mediates the electroreduction of U(VI). The bulk electrolysis at -0.55 V using the OTTLE showed that the absorbance at 660 nm attributable U(IV) species increased with time. These findings suggest that FMN may act as an electron shuttle of U(VI) reduction.
Ishikawa, Hirohisa
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no abstracts in English
Hiraga, Naoto; Ishii, Eiichi; Niinuma, Hiroaki
no journal, ,
no abstracts in English