Aoki, Katsunori; Yamanaka, Hiroki*; Watanabe, Kazuhiko*; Sugihara, Kozo
JAEA-Data/Code 2020-018, 45 Pages, 2021/02
Mizunami Underground Research Laboratory (MIU) Project is pursued by Japan Atomic Energy Agency (JAEA) in the crystalline host rock (granite) as a part of geoscientific study of JAEA, and underground facilities of MIU are constructed down to 500m blow the ground surface. As small amount of Uranium is normally contained in granite, high concentration of radon is sometimes detected in the air of the underground facilities constructed in granitic rocks depending on their ventilation conditions. Radon concentrations in underground facilities of MIU have been measured according to the excavation progress of underground facilities or the change of ventilation system. It is recognized that the data obtained by the actual measurement of radon concentration in such underground facilities are rare and valuable. This repot summarizes the measured data from fiscal 2010 to fiscal 2020, together with the information of ventilation conditions and air temperature which affect radon concentrations in underground facilities. The variation of the equilibrium factors of radon is also examined with the actually measured data. As a result, it has been found that radon concentration in the drift is high in summer and low in winter according to the natural ventilation caused by the seasonal temperature difference between in and out of the underground facilities. Furthermore, the temporary increase in the equilibrium factor of radon in the drift at the start of ventilation is supposed to be due to the aerosol increase by the ventilation flow, such as the dust blown up.
Fukuda, Kenji; Watanabe, Yusuke; Murakami, Hiroaki; Amano, Yuki; Aosai, Daisuke*; Hara, Naohiro*
JAEA-Data/Code 2020-012, 80 Pages, 2020/10
Japan Atomic Energy Agency has been investigating groundwater chemistry to understand the influence of excavation and maintenance of underground facilities as part of the Mizunami Underground Research Laboratory (MIU) Project in Mizunami, Gifu, Japan. In this report, we compiled data of groundwater chemistry and microbiology obtained at the MIU in the fiscal year 2019. In terms of ensuring traceability of data, basic information (e.g. sampling location, sampling time, sampling method and analytical method) and methodology for quality control are described.
Nishio, Kazuhisa*; Shimizu, Mayuko; Iyatomi, Yosuke; Hama, Katsuhiro
JAEA-Review 2020-013, 59 Pages, 2020/08
The Tono Geoscience Center (TGC) of Japan Atomic Energy Agency (JAEA) has been conducting geoscientific study in order to establish a scientific and technological basis for the geological disposal of HLW. Technical information of the result on the geoscientific study conducted at TGC is provided at the annual Information and Opinion Exchange Conference on Geoscientific Study of TGC for exchanging opinions among researchers and engineers from universities, research organizations and private companies. This document compiles the research presentations and posters of the conference in Mizunami on November 20, 2019.
Fukuda, Kenji; Watanabe, Yusuke; Murakami, Hiroaki; Amano, Yuki; Aosai, Daisuke*; Kumamoto, Yoshiharu*; Iwatsuki, Teruki
JAEA-Data/Code 2019-019, 74 Pages, 2020/03
Japan Atomic Energy Agency has been investigating groundwater chemistry to understand the influence of excavation and maintenance of underground facilities as part of the Mizunami Underground Research Laboratory (MIU) Project in Mizunami, Gifu, Japan. In this report, we compiled data of groundwater chemistry and microbiology obtained at the MIU in the fiscal year 2018. In terms of ensuring traceability of data, basic information (e.g. sampling location, sampling time, sampling method and analytical method) and methodology for quality control are described.
Fukuda, Kenji; Watanabe, Yusuke; Murakami, Hiroaki; Amano, Yuki; Hayashida, Kazuki*; Aosai, Daisuke*; Kumamoto, Yoshiharu*; Iwatsuki, Teruki
JAEA-Data/Code 2018-021, 76 Pages, 2019/03
Japan Atomic Energy Agency has been investigating groundwater chemistry to understand the influence of excavation and maintenance of underground facilities as part of the Mizunami Underground Research Laboratory (MIU) Project in Mizunami, Gifu, Japan. In this report, we compiled data of groundwater chemistry and microbiology obtained at the MIU in the fiscal year 2017. In terms of ensuring traceability of data, basic information (e.g. sampling location, sampling time, sampling method and analytical method) and methodology for quality control are described.
Ueno, Tetsuro; Takeuchi, Ryuji
JAEA-Data/Code 2017-003, 46 Pages, 2017/03
Tono Geoscience Center of Japan Atomic Energy Agency (JAEA) is pursuing a geoscientific research and development project namely the Mizunami Underground Research Laboratory (MIU) Project in crystalline rock environment in order to construct scientific and technological basis for geological disposal of High-level Radioactive Waste (HLW). The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction Phase (Phase II), and Operation phase (Phase III). As for The MIU Project (Phase II) was carried out from 2004 fiscal year, and has been started the Phase III in 2010 fiscal year. The groundwater inflow monitoring into shafts and research galleries, has been maintained to achieve the Phase II goals, begins in 2004 fiscal year and follow now. This document presents the results of the groundwater inflow monitoring from fiscal year 2014 to 2015.
Fukaya, Masaaki*; Takeda, Nobufumi*; Miura, Norihiko*; Ishida, Tomoko*; Hata, Koji*; Uyama, Masao*; Sato, Shin*; Okuma, Fumiko*; Hayagane, Sayaka*; Matsui, Hiroya; et al.
JAEA-Technology 2016-035, 153 Pages, 2017/02
The researches on engineering technology in the Mizunami Underground Research Laboratory (MIU) project in FY2016, detailed investigations of the (mechanical) behaviors of the plug and the rock mass around the reflood tunnel through ongoing reflood test were performed as part of (5) development of technologies for restoration and/or reduction of the excavation damage. As the result, particularly for the temperature change of the plug, its analytical results agree fairly well agree with the measurement ones. This means cracks induced by temperature stress can be prevented by the cooling countermeasure works reviewed in designing stage. In addition, for the behaviors of the plug and the bedrock boundary after reflooding the reflood tunnel, comparison between the results obtained by coupled hydro-mechanical analysis (stress-fluid coupled analysis) with the ones by several measurements, concluded that the model established based on the analysis results is generally appropriated.
Tsuji, Masakuni*; Kobayashi, Shinji*; Mikake, Shinichiro; Sato, Toshinori; Matsui, Hiroya
Procedia Engineering, 191, p.543 - 550, 2017/00
This paper shows the application of two post-grouting works to a gallery at 500 m depth of Mizunami Underground Research Laboratory in Japan. Three new grouting concepts were applied to the post-grouting works; a new grout material, a new injection system, and a new post-grouting zone. As for a grout material, "durable liquid-type colloidal silica grout (CSG)" was applied to seal the narrow fractures. As for an injection system, "complex dynamic grouting method" was applied to improve the penetrability of the grout material. The grouting works were successful in reducing the abundant water inflow from the rock mass with many fractures.
Nohara, Tsuyoshi; Saegusa, Hiromitsu*; Iwatsuki, Teruki; Hama, Katsuhiro; Matsui, Hiroya; Mikake, Shinichiro; Takeuchi, Ryuji; Onoe, Hironori; Sasao, Eiji
JAEA-Research 2015-026, 98 Pages, 2016/03
Tono Geoscience Center (TGC) of Japan Atomic Energy Agency (JAEA) is being performed Mizunami Underground Research Laboratory (MIU) Project, which is a broad scientific study of the deep geological environment as a basis of research and development for geological disposal of nuclear wastes, in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock. The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). The project goals of the MIU Project from Phase I through to Phase III are: (1) to establish techniques for investigation, analysis and assessment of the deep geological environment, and (2) to develop a range of engineering for deep underground application. This report summarizes the results of geoscientific study on Phase II to 500m depth. During Construction phase, we have evaluated of adequacy of techniques for investigation, analysis and assessment of the deep geological environment on Surface-based Investigation phase, and have established systematic methodology for stepwise investigation and evaluation of the geological environment on Construction phase. Further, with respect to design and construction of underground facilities, it was confirmed the validity of the engineering involved in the construction, maintenance and management of underground facilities.
Geoscientific Research Department, Tono Geoscience Center
JAEA-Review 2015-015, 39 Pages, 2015/09
In 2014, the JAEA presented the remaining critical issues based on synthesizing R&D results up to date, performed in the approach of whole JAEA reform reflecting the maintenance problems at the fast-breeder reactor "Monju". In this revision, research program of Phase III are restructured based on the critical issues presented in the approach of the whole JAEA reform.
Kuwabara, Kazumichi; Sato, Toshinori; Sanada, Hiroyuki; Takayama, Yusuke
JAEA-Research 2015-005, 378 Pages, 2015/07
This report presents the results of following rock mechanical investigations conducted at the -500m Stage. (1) Laboratory tests using cores and block samples obtained at the -500m Stage. (2) In-situ stress measurement using Compact Conical-ended Borehole Overcoring (CCBO) method at the -500m Stage. (3) In-situ stress measurements using Differential Strain Curve Analysis(DSCA) method at the -500m Stage. (4) Development of rock mechanical model.
Takayama, Yusuke; Sato, Toshinori; Onoe, Hironori; Iwatsuki, Teruki; Saegusa, Hiromitsu; Onuki, Kenji
Dai-43-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.313 - 318, 2015/01
In the Mizunami Underground Research Laboratory, groundwater recovery experiment is being conducted to construct the method to understand the transition of geological environment due to groundwater recovery at the -500m access and research gallery-north. As a part of this experiment, backfill test is planned using drilling pits filled with artificial materials (clay and concrete) to evaluate the influence on the surrounding rock mass due to the interaction of rock and artificial materials. In this study, numerical simulation of the backfill test has been carried out to predict the qualitative hydro-mechanical behavior.
Nohara, Tsuyoshi; Sakai, Toshihiro; Murakami, Hiroaki; Ishibashi, Masayuki
no journal, ,
Existing data was analyzed in order to understand Hydrological and Geological Characterization of deep subsurface structures in and around the Main Shaft fault at the Mizunami Underground Research Laboratory. As a result, in response to the low permeability structure of the Main Shaft Fault, fault gouges and alteration parts are found to be continuously distributed in the wall of the Main Shaft. One of the most high-permeable structure was estimated to be constituted by low-angle fractures with a sheet-like calcite. Shear of low angle fractures showed relatively low permeability. It may be possible to understand the permeability structure of these features in a drilling survey of granitic rocks.
Mikake, Shinichiro; Iwatsuki, Teruki; Matsui, Hiroya; Sasao, Eiji
no journal, ,
The MIU (Mizunami underground research laboratory project) has proceeded in three overlapping phases, "Phase I: Surface-based investigation", "Phase II: Construction" and "Phase III: Operation". The construction of research galleries in the MIU has been completed to the GL-500 m depth. The research activities in Phase III have been conducted in the underground since 2010. Current R and D activities include a gallery closure test on the -500m level to study recovery processes in the geological environment around a gallery after it has been backfilled and for the development of long-term monitoring technology, a post-excavation grouting experiment to demonstrate the feasibility of impermeable grout technology, and a mass transport experiment. This report introduces the next five years R&D plan and its current status.
Nohara, Tsuyoshi; Takeuchi, Ryuji; Sakai, Toshihiro
no journal, ,
Focusing on the characteristics of the faults and fractures of the MIU, based on analysis of existing data and on geological investigations, we examined the geological and hydrological features of the deep underground granitic rocks in the site scale. As a result, main permeable structures of granitic rocks can be associated with the old structures formed with the faulting and/or hydrothermal activity in geological times. Furthermore, we examined the distribution of the major permeable structures, based on the distribution of the geological structures.
Nohara, Tsuyoshi; Sakai, Toshihiro; Murakami, Hiroaki; Ishibashi, Masayuki
no journal, ,
It was carried out research on influences of the faults and fractures distribution and geological environment in granitic rocks, in the Mizunami Underground Research Laboratory (MIU) Project. The geological model was updated based on the information of the distributions of lithofacies and geological structures at a depth 500m research galleries, and besides, the validity of the geological model of the site scale developed in the Phase I is confirmed by comparing with the updated model. The relationship between the permeability and fracture filling materials in granitic rocks was examined. As a result, it is confirmed that the water permeability is different by the kind of filling mineral dominant.
Elena, K.*; Teklu, H.*; Wang, Y.*; Iwatsuki, Teruki; Ozaki, Yusuke
no journal, ,
In this study, Discrete Fracture Network Model (DFN) is built based on the fracture data observed in the Mizunami Underground Research Laboratory. 297 fractures data with discharge is analyzed for the estimation of stochastic quantity under the assumption that those fractures are permeable and have an great impact on the hydraulic conductivity field. Both models of fracture and hydraulic conductivity around the Closure Test Drift at the depth of 500m are generated from derived stochastic models. The hydraulic model is input into the numerical simulation. The matching of calculated and observed inflow into research tunnel indicates the validity of generated model and modeling approach for fractured rock. These results are a part of results in Task C of Decovalex2019.
Teklu, H.*; Elena, K.*; Wang, Y.*; Iwatsuki, Teruki; Ozaki, Yusuke
no journal, ,
In this study, the time variation of hydraulic head and Cl concentration during excavation of Closure Test Drift at the depth of 500m in Mizunami Underground Research Laboratory is simulated. The equivalent continuous porous medium model converted from Discrete Network Model is used to consider the highly heterogeneous feature of fractured rock. The simulated change in hydraulic head shows the good accordance with the observed data. However, the estimated time variations of Cl concentration show the slight change and can not reproduce the observed data. The improvement of prediction of change in Cl concentration is one of future task. These results are parts of results of Decvalex2019 Task C.