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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).
Hiraga, Naoto; Ishii, Eiichi; Niinuma, Hiroaki
no journal, ,
no abstracts in English
Mukai, Masayuki; Shimada, Taro; Tanaka, Tadao; Sukegawa, Takenori; Nakayama, Shinichi
no journal, ,
Nuclear Safety Research Center in JAEA has been conducting R&D activities to support national safety regulatory systems. (1) Research on safety assessment for decommissioning of nuclear fuel cycle facilities: A prototype computer code for fuel cycle facilities was developed by improving the code previously developed for nuclear reactor facilities. (2) Research on dose evaluation during dismantling: Values on evaluation parameters were obtained through the cutting test using actual contaminated pipes. Observed values for dispersion ratio of Co-60 and filtration efficiency indicated that existing recommendation values were conservative for safety assessment. (3) Research on site release on termination of decommissioning: A computer code was developed to calculate remaining radionuclide concentrations as site release criteria, and improved by adding practical settings for external and internal exposed doses. Preliminary calculations were conducted on typical land reuse scenario.
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.
Matsuzaki, Tatsuji; Iwatsuki, Teruki; Kunimaru, Takanori; Ota, Kunio; Shigeta, Naotaka
no journal, ,
no abstracts in English
Ebashi, Takeshi; Kawamura, Makoto; Inagaki, Manabu; Shibata, Masahiro; Chiba, Tamotsu*
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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.
Maekawa, Keisuke; Saegusa, Hiromitsu; Hiraga, Naoto; Tokiwa, Tetsuya; Kosaka, Hiroshi
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no abstracts in English
Tokiwa, Tetsuya; Niizato, Tadafumi; Maekawa, Keisuke; Asamori, Koichi; Abe, Hironobu
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no abstracts in English
Fuchiwaki, Hirotaka; Namekawa, Maki; Munakata, Masahiro; Kimura, Hideo
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no abstracts in English
Namekawa, Maki; Matsuba, Hisashi; Munakata, Masahiro; Kimura, Hideo
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no abstracts in English
Yabuuchi, Satoshi; Kunimaru, Takanori; Yokota, Hideharu; Yamamoto, Yoichi; Maekawa, Keisuke; Ishii, Eiichi; Hiraga, Naoto
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no abstracts in English
Sanada, Hiroyuki; Sugita, Yutaka; Daimaru, Shuji; Matsui, Hiroya; Kashiwai, Yoshio*
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no abstracts in English
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*
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no abstracts in English
Abe, Hironobu; Shimoyama, Tadashi; Yamasaki, Masanao*; Sanoki, Satoru*
no journal, ,
no abstracts in English