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Sawaguchi, Takuma; Takai, Shizuka; Sasagawa, Tsuyoshi; Uchikoshi, Emiko*; Shima, Yosuke*; Takeda, Seiji
MRS Advances (Internet), 8(6), p.243 - 249, 2023/06
In the intermediate depth disposal of relatively high-level radioactive waste, a method to confirm whether the borehole for monitoring is properly sealed should be developed in advance. In this study, groundwater flow analyses were performed for the hydrogeological structures with backfilled boreholes, assuming sedimentary rock area, to understand what backfill design conditions could prevent significant water pathways in the borehole, and to identify the confirmation points of borehole sealing. The results indicated the conditions to prevent water pathways in the borehole and BDZ (Borehole Disturbed Zone), such as designing the permeability of bentonite material less than or equal to that of the host rock, and grouting BDZ.
Park, Y.-J.*; Sawada, Atsushi; Ozutsumi, Takenori*; Tanaka, Tatsuya*; Hashimoto, Shuji*; Morita, Yutaka*
Proceedings of 3rd International Conference on Discrete Fracture Network Engineering (DFNE 2022) (Internet), 8 Pages, 2022/00
Safety analysis for underground disposal facilities for high-level radioactive waste requires thorough understanding of long-term groundwater flow and nuclide migration processes in geologic media. In the coastal subsurface systems, groundwater flow is defined by the complex interactions between freshwater of meteoric origin and denser saline water from the sea. In addition, sea levels are expected to fluctuate significantly due to a transgression and regression of the sea over the millions of years for safety analysis. This study presents long-term evolution of groundwater environment such as salinity concentration and flow velocity with focus of the interaction between fractures and matrix blocks in regional and near-field scale analysis framework for groundwater flow and nuclide migration for underground disposal facilities in hypothetical fractured crystalline coastal systems.
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.
Kamei, Gento
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 24(1), P. 1, 2017/06
As a preface of the Journal of Nuclear Fuel Cycle and Environment, published by the Atomic Energy Society of Japan, importance of understanding of underground in the context of geological disposal is related.
Deguchi, Akira*; Umeki, Hiroyuki*; Ueda, Hiroyoshi*; Miyamoto, Yoichi; Shibata, Masahiro; Naito, Morimasa; Tanaka, Toshihiko*
LBNL-1006984 (Internet), p.12_1 - 12_22, 2016/12
The H12 report demonstrated the feasibility of safe and technically reliable geological disposal in 1999. The Government of Japan re-evaluated the geological disposal program in terms of technical feasibility based on state-of-the-art geosciences and implementation process, because more than 10 years have passed from H12 and the Great Earthquake and nuclear accident have increased public concern regarding nuclear issues and natural hazards to cause accidents at nuclear facilities. Following the re-evaluation, the Government concluded further to promote geological disposal program, and thus the Basic Policy for Final Disposal was revised in 2015 including a new approach to siting process with identification of "Scientifically Preferable Areas". NUMO and relevant research organizations such as JAEA have been carrying out R and D activities to increase technical reliability for geological disposal. NUMO has started to develop a generic safety case.
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.
Yamaguchi, Tetsuji; Sawaguchi, Takuma; Tsukada, Manabu; Hoshino, Seiichi*; Tanaka, Tadao
Clay Minerals, 51(2), p.279 - 287, 2016/02
Times Cited Count：7 Percentile：24.23(Chemistry, Physical)Alteration of bentonite-cement interfaces and accompanying changes in diffusivity of tritiated water was experimentally investigated using intact hardened cement specimens. The alteration by carbonate solution was accompanied by mineralogical changes at the interface and a decrease in the diffusivity to 70% of the initial value after 180-day period. Another alteration under silicate system contacting hardened cement and compacted bentonite was accompanied by mineralogical changes at the interface and a decrease in the diffusivity to 71% of the initial value after 600-day period. The changes in the diffusivity were much less than those observed for mixed specimens of granulated hardened cement and bentonite where the diffusivity decreased down to 20% of the initial value over 180 days. The results were extrapolated to 15 years under simple assumptions and showed good agreement with those observed in the cement-argillite interface at Tournemire URL. Such an explanation enhances our confidence in our assessment of alteration of cement-bentonite systems and can be a base for using our data and models in long term assessment of radioactive waste disposal.
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.
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.
Nagano, Tetsushi; Nakayama, Shinichi
Genshiryoku Bakkuendo Kenkyu, 8(1), p.81 - 88, 2001/09
Japan Atomic Energy Research Institute has studied to predict the long-term migration of radionuclides in geosphere in terms of radioactive waste disposal. The research activity was introduced to junior high and high school students at a seminar of the Mineralogical Society of Japan. The content of the lecture was summarized.
Kimura, Hideo; Takano, Hideki; Muromura, Tadasumi
Journal of Nuclear Materials, 274(1-2), p.197 - 205, 1999/00
Times Cited Count：7 Percentile：49.64(Materials Science, Multidisciplinary)no abstracts in English
Klukas, M. H.*; Moltyaner, G. L.*; Takeda, Seiji; Yamazaki, L. S.*; Kozter, T. G.*
AECL-RC-2132, p.1 - 42, 1998/08
no abstracts in English
Kimura, Hideo; Matsuzuru, Hideo; Takano, Hideki; Muromura, Tadasumi
JAERI-Research 97-049, 25 Pages, 1997/07
JAERI-Research-97-049.pdf:1.42MB
no abstracts in English
Takeda, Seiji; ; Kimura, Hideo; Matsuzuru, Hideo
JAERI-Research 95-069, 47 Pages, 1995/11
JAERI-Research-95-069.pdf:1.65MB
no abstracts in English
Kimura, Hideo; Takahashi, Tomoyuki; ; Matsuzuru, Hideo
Journal of Nuclear Science and Technology, 32(3), p.206 - 217, 1995/03
Times Cited Count：4 Percentile：43.23(Nuclear Science & Technology)no abstracts in English
Kimura, Hideo; Takahashi, Tomoyuki; ; Matsuzuru, Hideo
JAERI-Research 94-028, 50 Pages, 1994/11
JAERI-Research-94-028.pdf:2.3MB
no abstracts in English
Takahashi, Tomoyuki; ; Kimura, Hideo; Matsuzuru, Hideo
JAERI-M 91-216, 31 Pages, 1992/01
no abstracts in English
; Wadachi, Yoshiki
JAERI-M 8044, 19 Pages, 1979/01
no abstracts in English
Co and 
Cs in the Sand Layer -; ; Wadachi, Yoshiki
JAERI-M 7642, 15 Pages, 1978/04
no abstracts in English
