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JAEA Reports

Data of radon measurement in underground facilities of Mizunami Underground Research Laboratory

Aoki, Katsunori; Yamanaka, Hiroki*; Watanabe, Kazuhiko*; Sugihara, Kozo

JAEA-Data/Code 2020-018, 45 Pages, 2021/02

JAEA-Data-Code-2020-018.pdf:4.54MB
JAEA-Data-Code-2020-018-appendix(DVD-ROM).zip:6.8MB

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.

JAEA Reports

Long term monitoring and evaluation of the excavation damaged zone induced around the wall of the shaft applying optical fiber sensor (Cooperative research)

Hata, Koji*; Niunoya, Sumio*; Uyama, Masao*; Nakaoka, Kenichi*; Fukaya, Masaaki*; Aoyagi, Kazuhei; Sakurai, Akitaka; Tanai, Kenji

JAEA-Research 2020-010, 142 Pages, 2020/11

JAEA-Research-2020-010.pdf:13.74MB
JAEA-Research-2020-010-appendix(DVD-ROM).zip:149.9MB

In the geological disposal study of high-level radioactive waste, it is suggested that the excavation damaged zone (EDZ) which is created around a tunnel by the excavation will be possible to be one of the critical path of radionuclides. Especially, the progress of cracks in and around the EDZ with time affects the safety assessment of geological disposal and it is important to understand the hydraulic change due to the progress of cracks in and around EDZ. In this collaborative research, monitoring tools made by Obayashi Corporation were installed at a total of 9 locations in the three boreholes near the depth of 370 m of East Shaft at the Horonobe Underground Research Laboratory constructed in the Neogene sedimentary rock. The monitoring tool consists of one set of "optical AE sensor" for measuring of the mechanical rock mass behavior and "optical pore water pressure sensor and optical temperature sensor" for measuring of groundwater behavior. This tool was made for the purpose of selecting and analyzing of AE signal waveforms due to rock fracture during and after excavation of the target deep shaft. As a result of analyzing various measurement data including AE signal waveforms, it is able to understand the information on short-term or long-term progress of cracks in and around EDZ during and after excavation in the deep shaft. In the future, it will be possible to carry out a study that contributes to the long-term stability evaluation of EDZ in sedimentary rocks in the deep part of the Horonobe Underground Research Laboratory by evaluation based on these analytical data.

JAEA Reports

Hydrochemical investigation at the Mizunami Underground Research Laboratory; Compilation of groundwater chemistry data in the Mizunami Group and the Toki Granite (fiscal year 2019)

Fukuda, Kenji; Watanabe, Yusuke; Murakami, Hiroaki; Amano, Yuki; Aosai, Daisuke*; Hara, Naohiro*

JAEA-Data/Code 2020-012, 80 Pages, 2020/10

JAEA-Data-Code-2020-012.pdf:3.55MB

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.

JAEA Reports

Proceedings of Information and Opinion Exchange Conference on Geoscientific Study, 2019

Nishio, Kazuhisa*; Shimizu, Mayuko; Iyatomi, Yosuke; Hama, Katsuhiro

JAEA-Review 2020-013, 59 Pages, 2020/08

JAEA-Review-2020-013.pdf:19.64MB

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.

JAEA Reports

Hydrochemical investigation at the Mizunami Underground Research Laboratory; Compilation of groundwater chemistry data in the Mizunami group and the Toki granite (fiscal year 2018)

Fukuda, Kenji; Watanabe, Yusuke; Murakami, Hiroaki; Amano, Yuki; Aosai, Daisuke*; Kumamoto, Yoshiharu*; Iwatsuki, Teruki

JAEA-Data/Code 2019-019, 74 Pages, 2020/03

JAEA-Data-Code-2019-019.pdf:3.53MB

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.

JAEA Reports

Hydrochemical investigation at the Mizunami Underground Research Laboratory; Compilation of groundwater chemistry data in the Mizunami group and the Toki granite (fiscal year 2017)

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

JAEA-Data-Code-2018-021.pdf:3.78MB

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.

Journal Articles

Status of rock dynamics study in Horonobe Underground Research Laboratory, Japan

Sato, Toshinori; Aoyagi, Kazuhei; Matsuzaki, Yoshiteru; Miyara, Nobukatsu; Miyakawa, Kazuya

Rock Dynamics; Experiments, Theories and Applications, p.575 - 580, 2018/06

Rock dynamics is one of key issue for research and development of techniques for safe geological disposal of high-level radioactive waste. Horonobe Underground Research Laboratory (URL) is off-site URL constructed in soft sedimentary rock to the depth of 350m with three shafts and three level experimental galleries. Earthquake-resistant design of underground openings, observation of seismic records and groundwater pressure change due to earthquakes, and excavation disturbed zone experiment have been performed relating to the study of rock dynamics in URL project. This paper shows current status of Horonobe URL project and results of earthquake-resistant design of shafts, observation of seismic records and groundwater pressure change due to the 2011 off the Pacific coast of Tohoku Earthquake.

JAEA Reports

Visualization of fractures in an Excavation Damaged Zone in the Horonobe Underground Research Laboratory (Joint research)

Aoyagi, Kazuhei; Chen, Y.*; Sakurai, Akitaka; Ishii, Eiichi; Ishida, Tsuyoshi*

JAEA-Research 2017-014, 49 Pages, 2018/01

JAEA-Research-2017-014.pdf:16.29MB

In this research, we performed the resin injection experiment at the 350 m gallery of the Horonobe Underground Research Laboratory in order to identify the three dimensional distribution of fractures induced around the gallery owing to excavation. To this end, the low viscosity resin mixed with a fluorescent substance was developed and applied to the in situ resin injection experiment. As a result, the resin was successfully penetrated into the fractures around the gallery without disturbing their situation and then fixed within them. After the experiment, the rock cores around the injection borehole were drilled for the observation. The observation under ultraviolet light revealed that the extent of the development of fractures was about 0.9 m into the borehole wall. In addition, the aperture of the fractures distributed within 0.3 m from the gallery wall was ranged 1 to 2 mm, and that distributed from 0.3 to 0.9 m was less than 1 mm. On the other hand, in the borehole televiewer (BTV) survey, only one fracture within 0.2 m from the wall could be detected owing to the resolution of the survey system. Thus, it is expected that the BTV survey underestimate the extent of the development of fractures.

Journal Articles

Analytical study on the Excavation Damaged Zone in the 350 m gallery at the Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Ishii, Eiichi

Shigen, Sozai Koenshu (Internet), 4(2), 7 Pages, 2017/09

no abstracts in English

JAEA Reports

Monitoring of groundwater inflow into research galleries in the Mizunami Underground Research Laboratory Project (MIU Project); From fiscal year 2014 to 2015

Ueno, Tetsuro; Takeuchi, Ryuji

JAEA-Data/Code 2017-003, 46 Pages, 2017/03

JAEA-Data-Code-2017-003.pdf:5.89MB
JAEA-Data-Code-2017-003-appendix(CD-ROM).zip:2.66MB

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.

JAEA Reports

Study on engineering technologies in the Mizunami Underground Research Laboratory (FY 2015); Development of recovery and mitigation technology on excavation damage (Contract research)

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

JAEA-Technology-2016-035.pdf:37.6MB

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.

Journal Articles

Post-grouting experiences for reducing groundwater inflow at 500 m depth of the Mizunami Underground Research Laboratory, Japan

Tsuji, Masakuni*; Kobayashi, Shinji*; Mikake, Shinichiro; Sato, Toshinori; Matsui, Hiroya

Procedia Engineering, 191, p.543 - 550, 2017/00

 Times Cited Count:9 Percentile:94.12

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.

Journal Articles

Confirmation of the applicability of low alkaline cement-based material in the Horonobe Underground Research Laboratory

Nakayama, Masashi; Niunoya, Sumio*; Minamide, Masashi*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 23(1), p.25 - 30, 2016/06

In Japan, any high-level radioactive waste repository is to be constructed at over 300m depth below surface. Tunnel support is used for safety during the construction and operation, and shotcrete and concrete lining are used as the tunnel support. Concrete is a composite material comprised of aggregate, cement and various additives. Low alkaline cement has been developed for the long term stability of the barrier systems whose performance could be negatively affected by highly alkaline conditions arising due to cement used in a repository. Japan Atomic Energy Agency (JAEA) has developed a low alkaline cement, named as HFSC (Highly fly-ash contained silicafume cement), containing over 60wt% of silica-fume (SF) and coal ash (FA). JAEA is presently constructing an underground research laboratory (URL) at Horonobe for research and development in the geosciences and repository engineering technology. HFSC was used experimentally as the shotcrete material in construction of part of the 350m deep gallery in Horonobe URL in 2013. The objective of this experiment was to assess the performance of HFSC shotcrete in terms of mechanics, workability, durability, and so on. HFSC used in this experiment is composed of 40wt% OPC (Ordinary Portland Cement), 20wt% SF, and 40wt% FA. This composition was determined based on mechanical testing of various mixes of the above components. Because of the low OPC content, the strength of HFSC tends to be lower than that of OPC in normal concrete. The total length of tunnel constructed using HFSC shotcrete is about 112m at 350m deep drift. The workability of HFSC shotcrete was confirmed by this experimental construction. In this report, we present detailed results of the in-situ construction test.

JAEA Reports

Project report on the construction phase at the Mizunami Underground Research Laboratory Project

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

JAEA-Research-2015-026.pdf:32.97MB

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.

JAEA Reports

Master Plan of the Mizunami Underground Research Laboratory Project

Geoscientific Research Department, Tono Geoscience Center

JAEA-Review 2015-015, 39 Pages, 2015/09

JAEA-Review-2015-015.pdf:28.06MB

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.

JAEA Reports

Mizunami Underground Research Laboratory Project; Rock mechanical investigations at the -500m stage

Kuwabara, Kazumichi; Sato, Toshinori; Sanada, Hiroyuki; Takayama, Yusuke

JAEA-Research 2015-005, 378 Pages, 2015/07

JAEA-Research-2015-005.pdf:125.5MB
JAEA-Research-2015-005.zip:0.53MB

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.

Journal Articles

Groundwater recovery experiment in Mizunami Underground Research Laboratory; Numerical simulation of H-M coupled behavior of rock and backfill materials to evaluate the influence on the surrounding rock

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.

Journal Articles

Modeling damage processes in laboratory tests at the Horonobe Underground Research Laboratory

Asahina, Daisuke*; Aoyagi, Kazuhei; Tsusaka, Kimikazu*; Houseworth, J.*; Birkholzer, J.*

Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 9 Pages, 2014/10

Journal Articles

An Investigation on mechanical properties of in-situ rock mass at the Horonobe Underground Research Laboratory

Tsusaka, Kimikazu*; Inagaki, Daisuke*; Niunoya, Sumio*; Jo, Mayumi*

Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 9 Pages, 2014/10

Oral presentation

Hydrological and geological characterization of deep subsurface structures in and around the main shaft fault at the Mizunami Underground Research Laboratory

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.

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