Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
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.
Nagao, Rina; Namekawa, Maki*; Totsuka, Masayoshi*; Nakata, Hisakazu; Sakai, Akihiro
JAEA-Technology 2021-009, 139 Pages, 2021/06
JAEA-Technology-2021-009.pdf:13.96MB
Japan Atomic Energy Agency is the implementing body of the near surface disposal of low-level radioactive waste (LLW) generated from research facilities and other facilities. Concrete-pit disposal are considered as a method of disposing of the LLW. Since the concrete-pits are placed at deeper position than the groundwater level, we need to consider that radionuclides might migrate with the flow of groundwater. Accordingly, in order to explain the safety of the concrete-pit disposal facility, it is necessary to investigate the flow of groundwater and the volumetric flow rate of leaching water from the facility. Therefore, in this report, sensitivity analysis of the volumetric flow rate of leaching water from concrete-pit was carried out by varying the permeability of cover-soil filled with in outside of the lateral sides of the bentonite mixed soil (BMS) and the conditions of the BMS on the upper part of the concrete-pits. As a result of the analysis, when the BMS is normal condition, the volumetric flow rate of leaching water from the concrete-pits is reduced by lowering permeability of the lateral cover-soil. However, in the case of occurring the deterioration of the function of BMS on the upper part of the concrete-pit, significant reduction of the volumetric flow rate of leaching water is not seen even if the permeability of the lateral cover-soil is lowered. Therefore, taking into consideration the possibility of the deterioration of the function of BMS on the upper part of the concrete-pit, it is necessary to consider that cover-soil with low permeability is equipped on the upper part of the BMS.
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.
Saegusa, Hiromitsu; Onoe, Hironori; Kohashi, Akio; Watanabe, Masahisa
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05
Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company is facing contaminated water issues. The amount of contaminated water is continuously increasing due to groundwater leakage into the underground part of reactor and turbine buildings. Therefore, it is important to understand the groundwater flow conditions at the site and to predict the impact of countermeasures taken for isolating groundwater from the source of the contamination, i.e. the reactor buildings. Installations, such as of land-side and sea-side impermeable walls have been planned as countermeasures. In this study, groundwater flow modeling has been performed to estimate the response of groundwater flow conditions to the countermeasures. From the modeling, groundwater conditions and changes in response to implementation of the countermeasures could be reasonably estimated. The results indicate that the countermeasures will decrease the volume of inflow into underground part of the buildings. This means that the countermeasures will be effective in reducing the discharge volume of contaminated groundwater to ocean.
Takeda, Seiji; Kimura, Hideo; Moltyaner, G. L.*; Klukas, M. H.*
Proceedings of 7th International Conference on Radioactive Waste Management and Environmental Remediation (ICEM '99) (CD-ROM), 7 Pages, 1999/00
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
Kimura, Hideo
Journal of Nuclear Science and Technology, 26(7), p.689 - 697, 1989/07
no abstracts in English
Teklu, H.*; Elena, K.*; Wang, Y.*; Iwatsuki, Teruki; Ozaki, Yusuke
no journal, ,
In this study, the time variation of hydraulic head and Cl concentration during excavation of Closure Test Drift at the depth of 500m in Mizunami Underground Research Laboratory is simulated. The equivalent continuous porous medium model converted from Discrete Network Model is used to consider the highly heterogeneous feature of fractured rock. The simulated change in hydraulic head shows the good accordance with the observed data. However, the estimated time variations of Cl concentration show the slight change and can not reproduce the observed data. The improvement of prediction of change in Cl concentration is one of future task. These results are parts of results of Decvalex2019 Task C.
