Development of modeling methodology for hydrogeological heterogeneity of the deep fractured granite in Japan

Onoe, Hironori; Ishibashi, Masayuki*; Ozaki, Yusuke; Iwatsuki, Teruki

International Journal of Rock Mechanics and Mining Sciences, 144, p.104737_1 - 104737_14, 2021/08

https://doi.org/10.1016/j.ijrmms.2021.104737

In this study, we investigated the methodology of modeling for fractured granite around the drift at a depth of 500 m in the Mizunami Underground Laboratory, Japan as a case study. As a result, we developed the fracture modeling method to estimate not only geological parameters of fractures but also hydraulic parameters based on the reproducibility of trace length distribution of fractures. By applying this modeling method, it was possible to construct a Discrete Fracture Network (DFN) model that can accurately reproduce the statistical characteristics of fractures.

Groundwater flow modeling in construction phase of the Mizunami Underground Research Laboratory project

Onoe, Hironori; Saegusa, Hiromitsu; Takeuchi, Ryuji

Doboku Gakkai Rombunshu, C (Chiken Kogaku) (Internet), 72(1), p.13 - 26, 2016/01

AA2015-0210.pdf:4.75MB

http://doi.org/10.2208/jscejge.72.13

The Japan Atomic Energy Agency is conducting the Mizunami Underground Research Laboratory (URL) project in Mizunami, Gifu, in order to establish scientific and technical basis for geological disposal of high-level radioactive waste. This paper comprehensively describes the result of groundwater flow modeling using data of hydraulic responses and hydrochemical changes due to URL construction. Technical know-how and methodology of hydrogeological monitoring and groundwater flow modeling were presented for characterization of hydraulic heterogeneities in fractured crystalline rock. Furthermore, effectivity of data acquisition of hydrochemical changes in groundwater for validation of result of groundwater flow modeling was indicated.

Compilation of Kinetic Data for Geochemical Calculations

Arthur, R. C,*; Savage, D.*; Sasamoto, Hiroshi; Shibata, Masahiro; Yui, Mikazu

JNC TN8400 2000-005, 61 Pages, 2000/01

JNC-TN8400-2000-005.pdf:2.83MB

Kinetic data, including rate constants, reaction orders and activation energies, are compiled for 34 hydrolysis reactions involving feldspars, sheet silicates, zeolites, oxides, pyroxenes and amphiboles, and for similar reactions involving calcite and pyrite. The data are compatible with a rate law consistent with surface reaction control and transition-state theoly, which is incorporated in the geochemieal software package EQ3/6 and GWB. Kinetic data for the reactions noted above are strictly compatible with the transition-state rate law only under far-from-equilibrium conditions. It is possiblethat the data are conceptually consistent with this rate law under both far-from-equilibrium and near-to-equilibrium conditions, but this should be confirmed whenever possible through analysis of original experimental results, Due to limitations in the availability of kinetic data for mineral-water reactions, and in order to simplify evaluations of geochemical models of groundwater evolution, it is convenient to assume local-equilibrium in such models whenever possible. To assess whether this assumption is reasonable, a modeling approach accounting for coupled fluid flow and water-rock interaction is described that can be used to estimate spatial and temporal scale of local equiliblium. The approach is demonstrated for conditions involving groundwater flow in fractures at JNC's Kamaishi in-situ tests site, and is also used to estimate the travel time necessary for oxidizing surface waters to migrate to the level of a HLW repository in crystalline rock. The question of whether local equilibrium is a reasonable assumption must be addressed using an appropriate modeling approach. To be appropriate for conditions at the Kamaishi site using the modeling approach noted above, the fracture fill must closely approximate a porous medium, groundwater flow must be purely advective and diffusion of solutes across the fracture-host rock boundary must not occur. Moreover, the ...

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JNC TN7400 2000-004, 21 Pages, 1999/12

JNC-TN7400-2000-004.pdf:0.54MB

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Investigation program in borehole MIU-2 for the Mizunami Underground Research Laboratory project in the Shobasama site

Ishikawa, Kiyoshi*; Mezaki, Yoshihiko*; Suzuki, Hideo*; Kai, Masanori*; Watanabe, Hajime*; Fujimori, Seiji*; Ishikawa, Junichi*

JNC TJ7420 99-016, 878 Pages, 1999/06

JNC-TJ7420-99-016.pdf:40.87MB

no abstracts in English

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Hisada, Tsukasa*; *; Imai, Hiroshi*; *

PNC TJ7409 98-002, 91 Pages, 1998/03

PNC-TJ7409-98-002.pdf:3.16MB

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*

PNC TJ1552 98-002, 773 Pages, 1998/03

PNC-TJ1552-98-002.pdf:28.07MB

no abstracts in English

Field test of the PNC mobile investigation system

*; *; Nakano, Katsushi

PNC TN7410 98-001, 37 Pages, 1998/02

PNC-TN7410-98-001.pdf:2.39MB

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.

Hydraulic test for evaluation of hydrophone VSP

Yabuuchi, Satoshi; Koide, Kaoru

PNC TN7410 97-041, 86 Pages, 1997/12

PNC-TN7410-97-041.pdf:3.83MB

This hydlraulic test was carried out at the test site of Tono Geoscience Center, Mizunami-shi, Gifu Pref. in order to evaluate the reliability of the hydraulic conductivity estimated from hydrophone VSP experiment. From March to April 1997, we carried out measurements of pore-water pressure at five depths and permeability tests at seven depths down to G.L. -300m, within a borehole drilled in granitic rock. We compared the results of hydraulic test with hydrophone VSP experiment on condition that a single open fracture existed, and we obtained two notable results. First, for the granitic rock at which a single open fracture was found by BTV and also detected by hydrophone VSP experiment, the hydraulic conductivity was 1.5410 cm/sec, while for the same granitic rock at which another single open fracture was found by BTV but not detected by hydrophone VSP experiment, the hydraulic conductivity was less than 610 cm/sec. Second, we converted the hydraulic conductivity of 1.5410 cm/sec which was obtained in a hydraulic test section of length 2.5m into an equivalent value for a single open fracture of width 1 mm. The converted value (3.810 cm/sec) was similar to the hydraulic conductivity estimated from hydrophone VSP experiment. In conclusion, the hydraulic test results shows that hydrophone VSP is useful to estimate an approximate hydraulic conductivity of a single open fracture.

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; ; ; ; ; ; Nakano, Katsushi

PNC TN7440 97-003, 255 Pages, 1997/04

PNC-TN7440-97-003.pdf:28.06MB

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