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JAEA Reports

Long-term monitoring of the stability of the gallery in Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Sakurai, Akitaka; Miyara, Nobukatsu; Sugita, Yutaka

JAEA-Research 2020-004, 68 Pages, 2020/06

JAEA-Research-2020-004.pdf:6.4MB
JAEA-Research-2020-004-appendix1(DVD-ROM).zip:636.84MB
JAEA-Research-2020-004-appendix2(DVD-ROM).zip:457.72MB
JAEA-Research-2020-004-appendix3(DVD-ROM).zip:595.19MB

In construction and operational phase of a high-level radioactive waste disposal project, it is necessary to monitor on mechanical stability of underground facility for long term. In this research, we measured the displacement of the rock around the gallery and the stress acting on support materials. Furthermore, we investigated the durability of measurement sensor installed in the rock mass and the support material such as concreate lining and steel support. As a result, optical fiber sensor is appropriate for measurement of the displacement of rock mass around the gallery, while it is enough to apply the conventional electric sensor for the measurement of stress acting on the support material in the geological environment (soft rock and low inflow). The result of the measurement in the fault zone in 350 m gallery, show that the stresses acting on both shotcrete and steel arch lib exceeded the value which will cause the instability of the gallery. However, as, we found no crack on the surface of the shotcrete. By observation on the surface of shotcrete, thus, it was concluded that careful observation of shotcrete around that section in addition to the monitoring the measured stress was necessary to continue. In other measurement sections, there was no risk for the instability of the gallery as a result of the investigation of the measurement result.

JAEA Reports

Synthesis report on the R&D for the Horonobe Underground Research Laboratory; Project carried out during fiscal years 2015-2019

Nakayama, Masashi; Saiga, Atsushi; Kimura, Shun; Mochizuki, Akihito; Aoyagi, Kazuhei; Ono, Hirokazu; Miyakawa, Kazuya; Takeda, Masaki; Hayano, Akira; Matsuoka, Toshiyuki; et al.

JAEA-Research 2019-013, 276 Pages, 2020/03

JAEA-Research-2019-013.pdf:18.72MB

The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies for geological disposal of High-level Radioactive Waste through investigations of the deep geological environment within the host sedimentary rock at Horonobe Town in Hokkaido, north Japan. The investigations will be conducted in three phases, namely "Phase 1: Surface based investigations", "Phase 2: Construction phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). According to the research plan described in the 3rd Mid- and Long- term Plan of JAEA, "Near-field performance study", "Demonstration of repository design option", and "Verification of crustal-movement buffering capacity of sedimentary rocks" are important issues of the Horonobe URL Project, and schedule of future research and backfill plans of the project will be decided by the end of 2019 Fiscal Year. The present report summarizes the research and development activities of these 3 important issues carried out during 3rd Medium to Long-term Research Phase.

JAEA Reports

Visualization of fractures in an excavation damaged zone in the Horonobe Underground Research Laboratory, 2 (Joint research)

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

JAEA-Research 2019-011, 50 Pages, 2020/03

JAEA-Research-2019-011.pdf:3.48MB

In this research, we performed the resin injection experiment at the 350 m Gallery of Horonobe Underground Research Laboratory in order to identify the distribution of fractures induced around the gallery owing to excavation. We also observed the rock cores obtained around the resin injection borehole under ultraviolet light. As a result, the extent of the development of EDZ fracture was 0.9 m from the gallery wall. In the depth within 0.4 m from the gallery wall, the density of the EDZ fracture is higher than the depth more than 0.4 m from the gallery wall. As a result of the analysis on the fracture aperture by image processing, the fractures with a large aperture (1.02 mm in maximum) were observed within 0.3 m from the gallery wall, while the maximum aperture was 0.19 mm in the depth more than 0.3 m from the gallery wall.

Journal Articles

Visualization of fractures induced around the gallery wall in Horonobe Underground Research Laboratory

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

Proceedings of 5th ISRM Young Scholars' Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future (YSRM 2019 and REIF 2019) (USB Flash Drive), 6 Pages, 2019/12

In the excavation of a repository for high-level radioactive waste (HLW) disposal, it is important to understand the hydro-mechanical characteristics of the Excavation Damaged Zone (EDZ) induced around the gallery because EDZ can lead to the migration pathway of radionuclides. Thus, we performed the resin injection experiment at the 350 m gallery of Horonobe Underground Research Laboratory in Japan to investigate the characteristics of fractures induced around the gallery wall in excavation. In the experiment, we developed a low viscosity resin mixed with a fluorescent substance and injected to the borehole drilled about 1 m in length. After the experiment, we overcored around the injection borehole. The observation on the cut surface of the overcore under ultraviolet light revealed that the fractures were distributed within 0.8 m from the gallery wall. Fractures are interconnected each other in particular within 0.25 m from the niche wall. Furthermore, fractures with large aperture (about 1.0 mm) were developed in that region. These observed results will be fundamental information for understanding of the fracturing process in the EDZ.

Journal Articles

A Measurement method of long-term mechanical stability of support and rock mass after the excavation of galleries; Case study in Horonobe Underground Research Center

Aoyagi, Kazuhei; Sakurai, Akitaka; Miyara, Nobukatsu; Sugita, Yutaka; Tanai, Kenji

Shigen, Sozai Koenshu (Internet), 6(2), 7 Pages, 2019/09

no abstracts in English

Journal Articles

A Study on the hydro-mechanical behavior in the excavation damaged zone in shaft sinking at the Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Sakurai, Akitaka; Tanai, Kenji

Dai-46-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.142 - 147, 2019/01

This research presents the hydro-mechanical behavior of EDZ in shaft sinking in the Horonobe underground Research Laboratory on the basis of the results of in situ hydraulic tests, acoustic emission (AE) measurements, and hydro-mechanical coupling numerical analysis. The AE sources were distributed within 1.5 m into the shaft wall; and hydraulic conductivity in the EDZ is 2 to 4 orders of magnitudes higher than that in no fractured area. On the other hand, on the basis of the result of numerical analysis, the maximum extent of the EDZ is 1.5 m into the gallery wall. This result is almost consistent with the trend of acoustic emission measurement and hydraulic test.

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.

JAEA Reports

In situ stress measurement at the 350 m Loop Gallery East at the Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Sakurai, Akitaka; Niunoya, Sumio*

JAEA-Data/Code 2016-022, 91 Pages, 2017/03

JAEA-Data-Code-2016-022.pdf:7.3MB
JAEA-Data-Code-2016-022-appendix(CD-ROM).zip:232.99MB

The objective of this report is to investigate the three dimensional stress state in the 350 m Loop Gallery (East) at the Horonobe Underground Research Laboratory. For the measurement, three boreholes, which are 17.0 m in length, were drilled. Hydraulic fracturing was applied as a stress measurement method. For the analysis, shut-in pressure of a transverse fractures, reopening pressure of longitudinal fractures and stress condition causing borehole breakouts were integrated into the equation; then stress state was calculated by inversion technique. As a result, considering the stress condition causing breakouts, the value of the maximum principal stress was 3.73 MPa, which is much smaller than the overburden pressure (about 6.0 MPa). The orientation of the maximum horizontal stress is almost vertical. The stress state is normal faulting.

JAEA Reports

Collection of measurement data in 2014 fiscal year at the Horonobe Underground Research Laboratory Project

Sakurai, Akitaka; Aoyagi, Kazuhei

JAEA-Data/Code 2016-003, 84 Pages, 2016/07

JAEA-Data-Code-2016-003.pdf:6.42MB
JAEA-Data-Code-2016-003-appendix(DVD-ROM).zip:184.29MB

The Horonobe Underground Research Laboratory (URL) Project has being pursued by Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formations at Horonobe, northern Hokkaido. The URL project consists of two major research areas, "Geoscientific Research" and "R&D on Geological Disposal Technologies", and proceeds in three overlapping phases, "Phase I: Surface-based investigations", "Phase II: Investigations during tunnel excavation" and "Phase III: Investigations in the underground facilities", over a period of around 20 years. The Phase I geoscientific research was carried out from March 2001 to March 2006 in parallel with design and execution scheme on URL facilities. In addition, identifying key issues that need to be addressed in the Phase II/III investigations was planned. At the beginning of the Phase II investigations, investigation reports related to measurement plan and observational construction program on shaft and drift excavation were published. The observational construction program summarizes the followings from the results of the Phase I investigations: measurements for safety and reasonable constructions, enhancement of shaft design and construction technologies and evaluation of appropriateness for the deep geological environment model estimated before shaft excavation. Currently, Phase III investigation related to geological disposal in underground facilities has been conducting. Also, measurement for consideration of long-term stability of the tunnel has been continued. This report summarizes the measurements data acquired at the West Shaft in 2014 fiscal year for the purpose of the basic data for carrying out the Observational Construction Program.

JAEA Reports

Measurement of the deformation behavior of the rock mass in the 350 m gallery in the Horonobe Underground Research Laboratory

Sakurai, Akitaka; Aoyagi, Kazuhei; Fujita, Tomoo; Motoshima, Takayuki*

JAEA-Data/Code 2015-023, 46 Pages, 2016/02

JAEA-Data-Code-2015-023.pdf:48.03MB
JAEA-Data-Code-2015-023-appendix(CD-ROM).zip:48.51MB

In a high level radioactive waste (HLW) disposal project, it is necessary to investigate the long-term behavior of thermos-hydro-mechanical-chemical of the rock mass around the engineered barrier system of the HLW waste for the safety assessment of the disposal system. In addition, long-term stability of the rock mass around the galleries are required for the disposal facility. Considering these backgrounds, the authors measure the deformation behavior of the vertical pit drilled on the floor of the 350 m gallery in the Horonobe Underground Research Laboratory. In situ measurements of the deformation of the pit and rock mass around the pit was conducted to apply to the assessment of the long-term deformation behavior. The authors describe the drilling of the vertical pit, geological observation, specification of the measurement instrument, measurement method, and result of the measurement in this report.

JAEA Reports

In situ stress measurements at the 350m pumping station in the Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Sakurai, Akitaka; Niunoya, Sumio*

JAEA-Data/Code 2015-010, 190 Pages, 2015/10

JAEA-Data-Code-2015-010.pdf:18.7MB
JAEA-Data-Code-2015-010-appendix(CD-ROM).zip:127.68MB

The objective of this report is to investigate the three dimensional stress state in the 350m pumping station at the Horonobe Underground Research Laboratory. For the measurement, four boreholes were drilled; three 20.0m long boreholes and one 6.0m long borehole. Hydraulic fracturing was applied as a stress measurement method. For the analysis, shut-in pressure of a transverse fractures, reopening pressure of longitudinal fractures and stress condition causing borehole breakouts were integrated into the equation; then stress state was calculated by inversion technique. As a result, considering the stress condition causing breakouts, the value of the maximum principal stress was 12 MPa, two times larger than overburden pressure. Furthermore, the ratio between maximum to minimum principal stress was 6. On the other hand, without considering the stress condition causing breakout, the maximum principal stress was 6 MPa; almost same as overburden pressure; the ratio between maximum to minimum principal stress was 2.7, thus the result was almost coincide with the result of surface-based investigation. The orientation of the maximum principal stress was N30W, dipping 45$$^{circ}$$ from vertical axis.

Journal Articles

Spontaneous activation behavior of Ni$$_{3}$$Sn, an intermetallic catalyst, for hydrogen production via methanol decomposition

Fan, M.*; Xu, Y.*; Sakurai, Junya*; Demura, Masahiko*; Hirano, Toshiyuki*; Teraoka, Yuden; Yoshigoe, Akitaka

International Journal of Hydrogen Energy, 40(37), p.12663 - 12673, 2015/10

 Times Cited Count:6 Percentile:77.45(Chemistry, Physical)

The catalytic properties of single-phase Ni$$_{3}$$Sn powder in the production of hydrogen via the decomposition of methanol were investigated in isothermal tests at 713, 793, and 873 K. The catalytic activity of Ni$$_{3}$$Sn significantly increased with time at 793 and 873 K, but not at 713 K, suggesting that Ni$$_{3}$$Sn is spontaneously activated at temperatures above 793 K. At these temperatures, Ni$$_{3}$$Sn showed high selectivity for H$$_{2}$$ and CO production and low selectivity for CH$$_{4}$$, CO$$_{2}$$, and H$$_{2}$$O production, indicating that methanol decomposition was the main reaction, and that side reactions such as methanation and water-gas shift reaction were suppressed. Surface analysis revealed that fine Ni$$_{3}$$Sn particles were formed during the reaction, accompanied by a small amount of deposited carbon. The formation of these particles was suggested to be the cause for the spontaneous activation of Ni$$_{3}$$Sn.

JAEA Reports

In situ stress measurement at the 250m Niche off the West Shaft No.1 in the Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Sakurai, Akitaka; Niunoya, Sumio*

JAEA-Data/Code 2015-012, 171 Pages, 2015/09

JAEA-Data-Code-2015-012.zip:33.31MB
JAEA-Data-Code-2015-012.pdf:28.27MB

The objective of this report is to investigate the three dimensional stress state in the 250 m Niche off the West Shaft No.1 at the Horonobe Underground Research Laboratory. For the measurement, three 20.0m long boreholes were drilled. Hydraulic fracturing was applied as a stress measurement method. For the analysis, shut-in pressure of a transverse fractures, reopening pressure of longitudinal fractures and stress condition causing borehole breakouts were integrated into the equation; then stress state was calculated by inversion technique. As a result of the in situ stress state measurement around the experimental area, the orientation of the maximum principal stress was estimated to be ESE-WNW, dipping 70$$^{circ}$$ from the vertical axis. The orientation of the minimum principal stress was NEN-SWS, dipping 60$$^{circ}$$ from vertical axis. The orientation of the principal stresses is almost coincided with the direction of borehole breakouts and longitudinal crack induced in the boreholes. The values of the maximum and minimum principal stresses were 2.6 MPa and 2.1 MPa, respectively.

JAEA Reports

In situ stress measurement at the 250m Niche off the South Shaft No.1 in the Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Sakurai, Akitaka; Niunoya, Sumio*

JAEA-Data/Code 2015-011, 182 Pages, 2015/09

JAEA-Data-Code-2015-011.pdf:33.41MB
JAEA-Data-Code-2015-011-appendix(CD-ROM).zip:41.95MB

The objective of this report is to investigate the three dimensional stress state in the 250 m Niche off the South Shaft No.1 at the Horonobe Underground Research Laboratory. For the measurement, three 20.0m long boreholes were drilled. Hydraulic fracturing was applied as a stress measurement method. For the analysis, shut-in pressure of a transverse fractures, reopening pressure of longitudinal fractures and stress condition causing borehole breakouts were integrated into the equation; then stress state was calculated by inversion technique. As a result of the in situ stress state measurement around the experimental area, the orientation of the maximum principal stress is estimated to be between E-W and ENE-WSW, dipping almost horizontal direction. This result agrees well with the estimated orientation of the main principal stress, the location of the borehole wall breakouts in 10-E250-M01 and the orientation of the generated crack in 10-E250-M03. The value of the maximum principal stress was 3.97 MPa.

Journal Articles

Effect of water vapor and hydrogen treatments on the surface structure of Ni$$_{3}$$Al foil

Xu, Y.*; Ma, Y.*; Sakurai, Junya*; Teraoka, Yuden; Yoshigoe, Akitaka; Demura, Masahiko*; Hirano, Toshiyuki*

Applied Surface Science, 315, p.475 - 480, 2014/10

 Times Cited Count:7 Percentile:59.31(Chemistry, Physical)

Journal Articles

Catalytic performance of Ni$$_{3}$$Sn and Ni$$_{3}$$Sn$$_{2}$$ for hydrogen production from methanol decomposition

Fan, M.*; Xu, Y.*; Sakurai, Junya*; Demura, Masahiko*; Hirano, Toshiyuki*; Teraoka, Yuden; Yoshigoe, Akitaka

Catalysis Letters, 144(5), p.843 - 849, 2014/05

 Times Cited Count:9 Percentile:68.61(Chemistry, Physical)

Oral presentation

Catalytic performance of Ni$$_{3}$$Sn alloy for hydrogen production from methanol decomposition

Fan, M.*; Xu, Y.*; Sakurai, Junya*; Demura, Masahiko*; Hirano, Toshiyuki*; Teraoka, Yuden; Yoshigoe, Akitaka

no journal, , 

Oral presentation

Catalytic properties of Ni$$_{3}$$Al foils for methane steam reforming

Xu, Y.*; Ma, Y.*; Sakurai, Junya*; Demura, Masahiko*; Hirano, Toshiyuki*; Teraoka, Yuden; Yoshigoe, Akitaka

no journal, , 

Oral presentation

Effect of steam treatments on surface morphology of Ni$$_{3}$$Al foil catalysts

Xu, Y.*; Ma, Y.*; Sakurai, Junya*; Teraoka, Yuden; Yoshigoe, Akitaka; Demura, Masahiko*; Hirano, Toshiyuki*

no journal, , 

Oral presentation

Oxidation of Ni$$_{3}$$Al(210) surface at room temperature using supersonic oxygen molecular beam; Real-time photoemission spectroscopic study with synchrotron radiation

Syu, Y.*; Sakurai, Junya*; Teraoka, Yuden; Yoshigoe, Akitaka; Demura, Masahiko*; Hirano, Toshiyuki*

no journal, , 

22 (Records 1-20 displayed on this page)