Tachi, Yukio; Ito, Tsuyoshi*; Gylling, B.*
Water Resources Research, 57(11), p.e2020WR029335_1 - e2020WR029335_20, 2021/11
This paper focuses on the scaling approach for sorption and diffusion parameters from laboratory to in-situ conditions using the dataset of LTDE-SD experiment performed at the sp HRL. The near-surface heterogeneities at both fracture surface and rock matrix could be evaluated by conceptual model with high porosity and diffusivity, and sorption capacity, and their gradual change at the near-surface zones. The modelling results for non-sorbing Cl-36 and weak-sorbing Na-22 could validate the model concept and the parameter estimation of porosity and diffusivity, by considering the disturbed zone of 5 mm thickness with gradual parameter changes. The De values of these cationic and anionic tracers showed typical cation excess and anion exclusion effects. The modelling results for high sorbing tracers (Cs-137, Ra-226, Ni-63 and Np-237) with different sorption mechanism could confirm the validity of the scaling approaches of Kd values as a function of particle size and their relation to the near-surface disturbances.
Mri, A.*; Mazurek, M.*; Ota, Kunio; Siitari-Kauppi, M.*; Eichinger, F.*; Leuenberger, M.*
Minerals (Internet), 11(10), p.1072_1 - 1072_17, 2021/10
Ichikawa, Yasuaki*; Kimoto, Kazushi*; Matsui, Hiroya
JAEA-Research 2019-005, 32 Pages, 2019/10
It is important to evaluate the mechanical stability around the geological repository for high-level radioactive waste, during not only the design, construction and operation phases, but also the post-closure period over several millennia. The rock mass around the tunnels could be deformed in response to time dependent behaviors such as creep and stress relaxation. Therefore, this study has started as a joint research with Okayama University from 2016. This report summarize the results of the joint research performed in fiscal year 2017 and 2018. Based on the research results obtained in fiscal year 2016, automatic measurement system was developed, which can collect very large data on surface elastic wave propagation in a short time, also the applicability of various kinds of parameters derived from measured elastic wave data was examined.
Toguri, Satohito*; Yahagi, Ryoji*; Okihara, Mitsunobu*; Takeuchi, Nobumitsu*; Kurosaki, Hiromi*; Matsui, Hiroya
JAEA-Technology 2018-017, 161 Pages, 2019/03
The Japan Atomic Energy Agency has been conducting research on three critical issues for development of: engineering techniques for underground construction, modelling techniques of mass transfer and tunnel backfilling methods at the Mizunami Underground Research Laboratory on the basis of Medium to Long-Term Plan of Japan Atomic Energy Agency. This report describes the overall plan of in-situ test to backfill a part of Mizunami Underground Research Laboratory, which is planned for "development of tunnel backfilling method".
Fukui, Katsunori*; Hashiba, Kimihiro*; Matsui, Hiroya
JAEA-Research 2017-010, 61 Pages, 2017/11
JAEA has started this study as a collaboration study with Tokyo University from 2016. In the fiscal year of 2016, creep testing on Tage tuff was continuously conducted. Existing theory of rate process and stochastic process was modified to be applied to evaluate effects of water, and then the modified theory was validated based on the results of strength and creep tests performed under dry and wet conditions. Furthermore, effects of water contents on stress-strain curves were examined by uniaxial compression testing under various water content conditions.
Kimoto, Kazushi*; Ichikawa, Yasuaki*; Matsui, Hiroya
JAEA-Research 2017-009, 18 Pages, 2017/11
JAEA has started this study as joint research with Okayama University from 2016. In fiscal year 2016, several kinds of elastic wave velocity were measured using ultra sonic sensors and laser Doppler vibrometer to evaluate the anisotropy of different elastic wave in granite. The velocity measurements were carried out focused on transmitted wave and surface wave. The results showed that strong anisotropy was observed in transmitted P- wave velocity while weak anisotropy was observed in transmitted S-wave and group velocity estimated by surface velocity measurement. In addition, data obtained from surface velocity measurement was partitioned into transmitted and reflected waves and analyzed them in detail. It resulted that elastic wave due to mineral particles consist of granite was dispersed; however, significant dispersion was only observed at specific location.
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.
Ichikawa, Yasuaki*; Kimoto, Kazushi*; Matsui, Hiroya; Kuwabara, Kazumichi; Ozaki, Yusuke
JAEA-Research 2016-018, 23 Pages, 2016/12
It is important to evaluate the stability of a repository for high-level radioactive waste not only during the design, construction and operation phases, but also during the post-closure period, for time frames likely exceeding several millennia or longer. The rock mass around the tunnels could be deformed through time in response to time dependent behavior. On the other hand, it was revealed that the chemical reaction of groundwater in a rock had an influence on the long-term behavior. An evaluation of the microcracks to have an influence on this mechanical and chemical coupled phenomena should be worked on chiefly. In fiscal year 2015, using a laser Doppler vibrometer that extends a frequency band up to 20 MHz, and measuring the surface wave transmitted through the granite specimens were estimated group velocity. As a result, group velocity until 100 kHz 500 kHz, revealed that tends to decrease while vibrating. The group speed estimate from a group delay was shown to be easier than the estimate by wave number - frequency spectrum. This is because in order to improve reliability, the estimated frequency band is by using a spatially averaged waveform. As a result obtained, in the case of the modeling by the viscoelastic theory of the granite and a microcrack nondestructiveness evaluation, it is thought that it is useful information in the future. In order to use the knowledge of this study, there is a need to clarify the correspondence between the microscopic properties of the medium such as a crack and crystal grain and the change of the group velocity.
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.
Ichikawa, Yasuaki*; Kimoto, Kazushi*; Sato, Toshinori; Kuwabara, Kazumichi; Takayama, Yusuke
JAEA-Research 2015-025, 31 Pages, 2016/03
It is important to evaluate the stability of a repository for high-level radioactive waste not only during the design, construction and operation phases, but also during the post-closure period, for time frames likely exceeding several millennia or longer. The rock mass around the tunnels could be deformed through time in response to time dependent behavior. On the other hand, it was revealed that the chemical reaction of groundwater in a rock had an influence on the long-term behavior. An evaluation of the microcracks to have an influence on these mechanical and chemical coupled phenomena should be worked on chiefly. In fiscal year 2014, this study performed numerical analysis to examine the supersonic scattering attenuation decrement behavior in the crystalline rock and a measurement sequentially last year. The measurement of the head and surface waves were carried out. As a result, group speed was provided. On the other hand, the spread scattering analysis of the elastic wave by the FDTD (Finite Difference Time-Domain) method made a numerical analysis. However, a laboratory finding is different from expectation of the simulation, and crystal anisotropic influence of a microcrack and rock-forming minerals is thought about as a cause of this estrangement. Therefore it was revealed that it was necessary to examine these two points of influence more in future.
Ichikawa, Yasuaki*; Kimoto, Kazushi*; Sato, Toshinori; Sanada, Hiroyuki; Kuwabara, Kazumichi
JAEA-Research 2014-027, 25 Pages, 2015/02
The rock and the rock mass are known to show time-dependent behavior such as creep and the stress-relaxation. It is to evaluate long-term rock mechanics stability that the important theme understanding the property. From the research study until now, it is rock mechanics and chemical coupled phenomenon to have an influence on the long-term behavior. It is a theme to develop technique to model this coupled phenomenon, and to analyze. About an evaluation of the microcrack to have an influence on this coupled phenomenon, it is the theme that we should work on in a long-term rock mass behavior study chiefly. This study developed numerical analysis to check the ultrasonic scattering decrement behavior by the microcrack of the crystalline rock and the measurement technique. The FDTD method which modelled a crack was used for numerical analysis by split node. It depends on the simulation technique that it developed that useful knowledge was provided by elastic wave modeling. On the other hand, the ultrasonic measurement in a rock sample was measured by the water immersion method. As a result, we understood that we could acquire useful information to evaluate the scattering decrement of an elastic wave in a rock sample.
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.
Metcalfe, R.*; Kawama, Daisuke*; Benbow, S. J.*; Tachi, Yukio
no journal, ,
Fukatsu, Yuta; Hu, Q.*; Tachi, Yukio
no journal, ,