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Koide, Kaoru; Nakano, Katsushi; Takeuchi, Shinji; Hama, Katsuhiro; ; Ikeda, Koki;
JNC TN7400 2000-014, 83 Pages, 2000/11
JNC-TN7400-2000-014.pdf:4.84MB
The Japan Nuclear Cycle Development Institute (JNC) has been conducting a wide range of geoscientific research in order to build a firm scientific and technological basis for the research and development of geological disposal. One of the major components of the ongoing geoscientific research programme is the Regional Hydrogeological Study (RHS) project in the Tono region, central Japan. The main goal of the RHS project is to develop and demonstrate surface-based investigation methodologies to characterize geological environments at a regional scale in Japan. The RHS project was initiated in 1992. The first five years of the project were devoted mainly to develop methodologies and techniques for deep borehole investigations in crystalline rock in Japan. Investigations to verify the performance of new instruments and methods for borehole drilling, hydraulic testing and groundwater sampling were conducted. In the last four years, surface-based investigations and a stepwise development of models of the geological environment have been carried out. To date, remote sensing, geological mapping, airborne and ground geophysical investigations, and measurements in eleven deep boreholes have been carried out. Hydro monitorring is continuing in these boreholes. Important results that have been obtained from these investigations include multi-disciplinaly information about the heterogeneity of lithology and hydraulic, geochemical and rock mechanical properties of the granitic rock, and evolution of the groundwater geochemistry. Technical knowledge and experience have been accumulated, which allow application of the methodologies and techniques to characterize the geological environment in crystalline rock. The results from these R%D activities were used as prime inputs for the H12 report that JNC submitted to the Japanese Government in l999. Results from such R&D is also acknowledged by other geoscientific studies in general. JNC will synthesize the results from R&D ...
*
JNC TN1440 2000-010, 145 Pages, 2000/11
JNC-TN1440-2000-010.pdf:6.19MB
no abstracts in English
Koide, Kaoru; Nakano, Katsushi; ; ; ; Saito, Hiroshi; Takeuchi, Shinji
JNC TN7410 2000-001, 56 Pages, 2000/04
Toyama, Shigeyuki*; Wakamatsu, Hisanori; Okazaki, Hikoya
JNC TJ7440 2000-019, 17 Pages, 2000/03
JNC-TJ7440-2000-019.pdf:1.95MB
no abstracts in English
Toyama, Shigeyuki*; Wakamatsu, Hisanori; Okazaki, Hikoya
JNC TJ7440 2000-018, 55 Pages, 2000/03
JNC-TJ7440-2000-018.pdf:9.57MB
no abstracts in English
*; *
JNC TJ7440 2000-005, 45 Pages, 2000/03
JNC-TJ7440-2000-005.pdf:2.72MB
no abstracts in English
*; Aizawa, Takao*; *
JNC TJ7420 2000-006, 54 Pages, 2000/03
JNC-TJ7420-2000-006.pdf:16.6MB
no abstracts in English
*; *
JNC TJ7400 2000-001, 79 Pages, 2000/02
JNC-TJ7400-2000-001.pdf:3.07MB
no abstracts in English
Sasamoto, Hiroshi; Yui, Mikazu; Randolph C Arthu*
JNC TN8400 99-074, 84 Pages, 1999/12
Hydrochemical investigation of Tertiary sedimentary rocks at JNC's Tono in-situ tests site indicate the groundwaters are: (1)meteoric in origin, (2)chemically reducing at depths greater than a few tens of meters in the sedimentary rock, (3)relatively old [carbon-14 ages of groundwaters collected from the lower part of the sedimentary sequence range from 13,000 to 15,000 years BP (before present)] (4)Ca-Na-HCO
type solutions near the surface, changing to Na-HCO type groundwaters with increasing depth. The chemical evolution of the groundwaters is modeled assuming local equilibrium for selected mineral-fluid reactions, taking into account the rainwater origin of these solutions. Results suggest it is possible to interpret approximately the "real" groundwater chemistry (i.e., pH, Eh, total dissolved concentrations of Si, Na, Ca, K, Al, carbonate and sulfate) if the following assumptions are adopted: (1)CO
concentration in the gas phase contacting pore solutions in the overlying soil zone = 10
bar, (2)minerals in the rock zone that control the solubility of respective elements in the groundwater include; chalcedony (Si), albite (Na), kaolinite (Al), calcite (Ca and carbonate), muscovite (K) and pyrite (Eh and sulfate). It is noted, however, that the available field data may not be sufficient to adequately constrain parameters in the groundwater evolution model. In particular, more detailed information characterizing certain site properties (e.g., the actual mineralogy of "plagioclase", "clay" and "zeolite") are needed to improve the model. Alternative conceptual models of key reactions may also be necessary. For this reason, a model that accounts for ion-exchange reactions among clay minerals, and which is based on the results of laboratory experiments, has also been evaluated in the present study. Further improvements of model considering ion-exchange reactions are needed in future, however.
Ijiri, Yuji; ; *; Watari, Shingo; K.E.Web*; *; *
JNC TN8400 99-092, 91 Pages, 1999/11
JNC has been developed the performance assessment approaches for both fractured rock and porous rock. An equivalent continuum model is incorporated for solving the radionuclide migration in porous rock, while a discrete fracture network model is incorporated for solving the radionuclide migration in fractured rock (see more detail in Sawada et al. [1999]). This report describes the methodology, the data and the results of the performance assessment of porous rock. From the results of radionuclide migration analyses that were based on the hydrogeological properties obtained from the Neogene sedimentaly rock at the Tono mine, it was found that the release rate of selenium-79 and cesium-135 are dominant in porous rock. The sensitivity analyses using one-dimensional porous model revealed that hydraulic conductivity has more influences on the results than porosity does. In addition, it was found that smaller distribution coefficients of sandstone yield higher release rate than mudstone and tuff, and smaller distribution coefficients of saline water conditions yield higher release rate than fresh water conditions. The radionuclide migration in Neogene sedimentaly rock, where flow in rock matrix as well as in fractures are significant, was evaluated by superposing the results of porous model and fracture model. Since fracture model tends to yield more conservative results than porous model, it is obvious that the performance of Neogene sedimentary rock can be conservatively assessed by fracture model alone. The nuclide migration analyses performed in this report were based on the hydrogeological properties obtained at the depth between 20 meters and 200 meters frrom the ground surface. Therefore, it should be noted that the release rate at the depth of a future repository in Neogene sedimentary rock, 500 m, will be smaller than that shown in this report due to peemeability decrease from 200 m to 500 m.
Toyama, Shigeyuki*; Wakamatsu, Hisanori; Okazaki, Hikoya
JNC TJ7440 99-031, 22 Pages, 1999/09
no abstracts in English
Ishikawa, Kiyoshi*; Mezaki, Yoshihiko*; Suzuki, Hideo*; Kai, Masanori*; Watanabe, Hajime*; Fujimori, Seiji*; Ishikawa, Junichi*
JNC TJ7420 99-016, 878 Pages, 1999/06
no abstracts in English
Itamoto, Masaharu*; Tanaka, Masahiro*; Tanno, Takeo*
PNC TJ7592 98-001, 166 Pages, 1998/03
None
*; *; Nakano, Katsushi
PNC TN7410 98-001, 37 Pages, 1998/02
Power Reactor and Nuclear Fuel Development Corporation (PNC) has been developing groundwater research instruments in order to characterize hydraulic and geochemical environments in the deep underground. As part of this development programme, a support system was developed in 1996 to conduct groundwater investigations efficiently. This system, called the PNC Mobile Investigation System, consists of 5 units: a data acquisition and analysis unit, a maintenance unit, a hoisting unit, a cable drum for hydraulic tests (Type I), and a cable drum for groundwater sampling (Type II). The system is the following features: (1) Groundwater investigation is possible without a drill machine and rig. (2) Long term investigation is possible without housing facilities and utilities. (3) Maintenance of instruments is possible in the field. (4) Control units, such as the computer, are well protected from the external environment. (5) Groundwater analysis is possible in the field. (6)Recovery of instruments stuck in the borehole is possible using the emergency hoisting unit. The first field test of this system was performed in February and March, 1997. Through this test, it was confirmed that the system had met its performance design when combined with a proper hydraulic test instrument. Much useful information for future improvements to the system was also obtained.
Matsuoka, Kiyoyuki*; Sakurai, Yutaka*
PNC TJ7586 98-002, 63 Pages, 1998/02
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