Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Kabasawa, Satsuki; Yamaguchi, Masaaki; Hirano, Fumio; Kato, Tomoko
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 32(1), p.10 - 22, 2025/06
In nuclide migration analyses for the safety assessments of geological disposal, when there is not necessarily sufficient confidence knowledge and data required for modeling phenomena, analyses are conducted using sufficiently conservative depending on the reliability of the technical basis, such as selecting data settings and modeling that yield severe results. There is a high level ofuncertainty for setting a parameter value of dispersion length used for the nuclide migration analysis, due to the difficulty in measuring field scale data. However, the effects of fluctuation of dispersion length on maximum nuclide release rate has not yet been fully understood. In this study, the effect of fluctuation of dispersion length on maximum nuclide release rate was investigated. Specifically, a series of the sensitivity analysis focusing on not only the effect of fluctuation of dispersion length but also the effect of parameters related to the retardation effect such as distribution coefficient and half-life of nuclides was performed for fracture medium. As a result, it was suggested the maximum nuclide release rate may increase due to the shortened nuclide transit time as the dispersion length increases. When peak of the nuclide release rate is less than the half-life of the nuclide, the increase of the maximum release rate due to an increase in the dispersion length remains limited to a few times. On the other hand, in case of exceeding half-life, the maximum nuclide release rate increases ten times or more as the maximum release rate occurrence time of the release rate decreases. These findings would contribute to setting the conservative value of dispersion length taking the uncertainty into consideration.
Yamaguchi, Masaaki; Suzuki, Yuji*; Kabasawa, Satsuki; Kato, Tomoko
JAEA-Data/Code 2024-001, 21 Pages, 2024/03
JAEA-Data-Code-2024-001.pdf:3.45MB
JAEA-Data-Code-2024-001-appendix(CD-ROM).zip:8.0MB
Model catchments have developed for use in testing various assessment models that can consider specific surface environmental conditions such as topography, riverine systems, and land use in the biosphere assessment of HLW geological disposal. The model catchments consist of the topography and riverine system of the catchment area created using existing tools, as well as land use and population distribution, river discharge, sediment flux data set by algorithms from topographical data. Datasets of three types of model watersheds (Types 1 to 3, watershed area: 730 to 770 km
) with different topographical characteristics have released as raster data that can be handled by geographic information systems (GIS). Since the model catchments were created virtually reflecting as much as possible the main characteristics of Japan's surface environment, they can be used as a test bed for conducting hydraulic/mass transport analysis to set the GBI and compartment model.
Minari, Eriko*; Kabasawa, Satsuki; Mihara, Morihiro; Makino, Hitoshi; Asano, Hidekazu*; Nakase, Masahiko*; Takeshita, Kenji*
Journal of Nuclear Science and Technology, 60(7), p.793 - 803, 2023/07
Times Cited Count：3 Percentile：33.51(Nuclear Science & Technology)Kawamura, Makoto; Nishiyama, Nariaki; Komatsu, Tetsuya; Jia, H.*; Koizumi, Yukiko*; Kabasawa, Satsuki; Umeda, Koji*
no journal, ,
In performance assessment of geological disposal of high-level radioactive waste, the impact of long-term changes in the surface environment, including topography caused by uplift and erosion, is important because the assessment period exceeds hundreds of thousands of years. One of the effects of uplift and denudation on the assessment of nuclide migration is the change in the location of groundwater discharge and recharge areas due to changes in topographical relief, such as river denudation, which is expected to affect the biosphere assessment process. As a tool to examine this issue, a "Analytical Tool of Evolution of Topography and Repository Depth" has been developed. On the other hand, it is necessary to verify how realistic the terrain created by this tool is for the performance assessment of the repository. In particular, there are few studies on transverse landforms formed by river cross section. In this report, we attempted a similar topographical analysis using actual and virtual topographical data for rivers, and report the results of a comparison and examination with river cross sections and runoff indexes, which are basic information necessary for performance assessment of disposal sites.
Nishiyama, Nariaki; Kawamura, Makoto; Komatsu, Tetsuya; Jia, H.*; Koizumi, Yukiko*; Kabasawa, Satsuki; Nakanishi, Toshimichi*; Umeda, Koji*
no journal, ,
no abstracts in English
Kawamura, Makoto; Nishiyama, Nariaki; Komatsu, Tetsuya; Jia, H.*; Koizumi, Yukiko*; Kabasawa, Satsuki; Nakanishi, Toshimichi*; Umeda, Koji*
no journal, ,
In geological disposal projects and safety regulations for HLW, one of the challenges in surveying and evaluating technology related to uplift and erosion, which is important in site selection and safety assessment of geological disposal, is that in the distant future, topography mainly due to river undercuts will occur. It is necessary to be able to quantitatively evaluate the changes and effects that these changes have on the underground geological environment. Among the geological environmental conditions, changes in groundwater recharge areas and outflow areas are important when building performance evaluation models because they can change the flow direction of surface water infiltration into the ground or groundwater outflow to the surface. The most reliable way to evaluate recharge and discharge areas is to use actual measured data on precipitation and river flow. However, when dealing with past or future topography, or hypothetical topography generated by simulations of topographical change, actual measurements are not possible, and so technology is required to indirectly estimate the area from topographical information. As one of the research technologies, a method has been developed to measure topographical features using a digital elevation model, calculate runoff volume using statistical analysis techniques, and visualize it as an index. In previous studies, we also attempted to apply this method to three rivers which have different drainage basin areas and uplift rates, and were able to present, to a certain extent quantitatively, results that are consistent with the general understanding that areas where high-altitude divided drainage basins are concentrated are high, meaning that surface water tends to flow more easily. Here, following previous studies, we report an example of applying the same method to a virtual topography created by simulating topographical change, and comparing and examining it with an actual river.
Mihara, Morihiro; Kabasawa, Satsuki; Suzuki, Yuji*; Kato, Tomoko
no journal, ,
no abstracts in English
Suzuki, Yuji*; Mihara, Morihiro; Kabasawa, Satsuki; Kato, Tomoko
no journal, ,
no abstracts in English
Kabasawa, Satsuki; Yamaguchi, Masaaki; Ebashi, Takeshi; Makino, Hitoshi; Minari, Eriko*
no journal, ,
no abstracts in English
Sakamoto, Michihito*; Wakasugi, Keiichiro*; Kabasawa, Satsuki; Yamaguchi, Masaaki
no journal, ,
no abstracts in English
Kabasawa, Satsuki; Sakamoto, Michihito*; Takahashi, Yuta; Yamaguchi, Masaaki
no journal, ,
no abstracts in English
Kabasawa, Satsuki; Sakamoto, Michihito*; Takahashi, Yuta; Yamaguchi, Masaaki
no journal, ,
no abstracts in English
Minari, Eriko*; Kabasawa, Satsuki; Mihara, Morihiro; Makino, Hitoshi; Nakase, Masahiko*; Asano, Hidekazu*; Takeshita, Kenji*
no journal, ,
As a study on long-term safety of geological disposal of high-level waste (HLW) generated during reprocessing spent mixed oxide fuel in light water reactors (MOX-LWRs), two types of HLW are considered. One is HLW generated from MOX-LWR reprocessing and another is blended MOX-UO
HLW generated during reprocessing process whereby MOX fuels are diluted by UO fuels. Radionuclide migration analyses for those two HLWs are conducted, and commonalities and differences between two HLWs in the viewpoint of long-term safety are discussed.
Kabasawa, Satsuki; Suzuki, Yuji*; Mihara, Morihiro; Kato, Tomoko
no journal, ,
no abstracts in English
Yamaguchi, Masaaki; Kato, Tomoko; Suzuki, Yuji*; Kabasawa, Satsuki; Mihara, Morihiro; Makino, Hitoshi
no journal, ,
The topography and repository depth transition analysis tool developed for inland areas has been expanded to accommodate coastal areas (TARTAN-II), taking into consideration sediment transport from land to ocean, and their spatiotemporal change due to sea-level and climate changes.
Sakamoto, Michihito*; Wakasugi, Keiichiro*; Kabasawa, Satsuki; Yamaguchi, Masaaki
no journal, ,
The topography is affected by long term uplift and erosion, which also causes change of the depth of the repository site. In addition, nuclide migration paths and outflow points on the ground surface change according to the changes in topography and the repository depth. In this study, the topographical transition analysis was performed focusing on the difference in the topographical transition due to the difference in the uplift rate, and the groundwater flow analysis was performed based on that. In addition, nuclide migration paths were evaluated considering the changes in topography and repository depth. As a result, it was indicated that the runoff points from the repository near the ground surface would change according to the uplift rate.
