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.

Study on analysis methodology of AE signal wave at great depth excavation

Niunoya, Sumio*; Hata, Koji*; Uyama, Masao*; Aoyagi, Kazuhei; Wakasugi, Keiichiro

Dai-45-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.226 - 231, 2018/01

The objective of this research is to investigate the long-term hydro-mechanical behavior of rock mass around the shaft in the Horonobe Underground Research Laboratory (URL). The long-term monitoring has been carried out by optical AE sensors, optical water pressure sensors, and optical temperature sensors below 350m depth of the shaft in the Horonobe URL. From the first analytical results, it was too hard to discriminate the uncleared AE wave by using the resonant characteristic. Thus, at this time, we tried to reanalysis by using the half width of spectrum, we could discriminate it correctly as AE from the breaking of rock.

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.

Laboratory testing of rock core samples from pre-excavation grouting area at Mizunami Underground Research Laboratory

Uyama, Masao*; Hitomi, Takashi*; Nakashima, Satoru*; Sato, Toshinori; Sanada, Hiroyuki; Aoyagi, Yoshiaki

JAEA-Research 2015-010, 67 Pages, 2015/10

JAEA-Research-2015-010.pdf:32.34MB
JAEA-Research-2015-010-appendix(CD-ROM).zip:528.25MB

Japan Atomic Energy Agency has been conducting a research project on (Grouting Technology Development for the Radioactive Waste Repository) funded by Ministry of Economy, Trade and Industry (METI), Japan. As a part of the project, various investigations were carried out in the -200m Refuge Niche where pre-excavation grouting was performed and the distribution of the injected grouting material, also the effectiveness of grouting penetration for reduction of groundwater inflow were confirmed As the continuation of these investigations, chemical influences of grouting material on the rock mass were determined through (Laboratory testing of rock core samples from pre-excavation grouting area at Mizunami Underground Research Laboratory). Specifically, core samples were obtained by check boring at where infiltration solidification of the grouting material was expected, and X-ray florescent analysis and Transmission Electron Microscope observation were performed focused on the contact parts of the grouting material and rock mass in fractures. As a result, the chemical influences of grouting material on the rock mass were identified.

Analytical study on uranium measurement in uranium waste drums by the fast neutron direct interrogation method

Komeda, Masao; Ozu, Akira; Haruyama, Mitsuo; Takase, Misao*; Kureta, Masatoshi; Nakatsuka, Yoshiaki; Zaima, Naoki; Nakashima, Shinichi; Otsuka, Yoshimasa

Proceedings of INMM 55th Annual Meeting (Internet), 9 Pages, 2014/07

We have researched and developed the FNDI method for a long time through experiments in NUCEF in JAEA Tokai. Referred from the pilot machine, we designed a demonstrator, called as JAWAS-N, for applying to non-destructive assay tools for uranium waste drums in JAEA Ningyo. In this paper, we present the modeling and the simulations concerning JAWAS-N's characteristics, and discuss for practical use compared analytical results with obtained some experimental data.

Investigation methodology for influence of cement material from grouting origin to granite

Uyama, Masao*; Hitomi, Takashi*; Sato, Toshinori

Doboku Gakkai Heisei-25-Nendo Zenkoku Taikai Dai-68-Kai Nenji Gakujutsu Koenkai Koen Gaiyoshu (DVD-ROM), 2 Pages, 2013/09

no abstracts in English

Basic study on surface chemical combination between beryllium metal and hydrogen isotope gas, 2

Ito, Masayasu; Kitagishi, Shigeru; Hanawa, Yoshio; Tsuchiya, Kunihiko; Hatano, Yuji*; Matsuyama, Masao*; Nagasaka, Takuya*; Hishinuma, Yoshimitsu*

Annual Report of National Institute for Fusion Science; April 2011 - March 2012, P. 535, 2012/12

http://www.nifs.ac.jp/report/annrep12/pdf/535.pdf

Beryllium has been utilized as a moderator and/or reflector in a number of material testing reactors. Beryllium is also supposed to be widely used in fusion reactors as neutron multiplier and protective walls of plasma facing components. It is important to perform the characterization of the different grade beryllium such as the productivity, mechanical and chemical properties and the interaction under water and/or gas environment. In this study, three kinds of beryllium (S-200F, S-65H, I-220H) were prepared, and corrosion test and surface analysis of these beryllium samples were carried out for life time expansion under pure water. As a result, the surface change of each Be sample was observed by the corrosion test and influenced by the content of BeO and the grain size.

Development of grouting technologies for HLW disposal in Japan, 2; In-situ grouting test program and site investigation results at the Grimsel Test Site in Switzerland

Nakanishi, Tatsuro; Tsuda, Hidenori; Abumi, Kensho*; Uyama, Masao*; Onishi, Yuzo*

Proceedings of 7th Asian Rock Mechanics Symposium (ARMS-7) (USB Flash Drive), p.682 - 691, 2012/10

JAEA has been developing grouting materials and technologies with the consideration of long term chemical interaction between the grout material and the rock mass as a natural barrier. This paper describes the in-situ grout injection test program carried out in the fractured granite of the Grimsel Test Site (GTS) in Switzerland, which has been set up to increase knowledge and understanding of the design of grouting in order to reduce the grout penetration area into the rock mass and of the results of the site investigation. The grout injection test project at the GTS has been carried out in several stages. The site investigation results of all six boreholes were then used to determine the best location for the final grout injection test. The staged approach proved to be a good way not only to determine the best location for the grout injection test, but also to focus on the best approach in the next stages by identifying and mitigating possible problems before they occurred.

Development of grouting technologies for geological disposal of high level waste in Japan, 1; Preliminary study for in-situ grout injection test in crystalline rock mass test site

Nakanishi, Tatsuro; Fujita, Tomoo; Tsuda, Hidenori; Tanaka, Tatsuya*; Uyama, Masao*; Onishi, Yuzo*

Dai-41-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.71 - 76, 2012/01

Grouting technology is fundamental to the safe and efficient construction of underground facilities for the geological disposal of high level waste in Japan. The Japan Atomic Energy Agency has been developing grouting materials and technologies with consideration to the long term chemical interactions between the grout material and the natural barrier rock mass. An in-situ grout injection test has been carried out at the Grimsel Test Site to optimize grouting design.

Stability of Nal(Tl) detector for tritium monitor of BIXS use to hot environment

Kawamura, Yoshinori; Shu, Wataru*; Matsuyama, Masao*; Yamanishi, Toshihiko

Fusion Science and Technology, 60(3), p.986 - 989, 2011/10

https://doi.org/10.13182/FST11-A12581

Assuming the blanket sweep gas at the outlet of the blanket, tritium gas monitor by -ray induced X-ray spectroscopy has been modified, and has measured tritium at 120 C. The counting rate at 120 C was about 1/2 of that at the room temperature. In this work, the measurement system was a closed system. When two systems have same volume and same pressure, the number of molecules in higher temperature system is smaller. This is one of the causes of small counting rate. The deterioration of the scintillator after heating was not observed.