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Onoe, Hironori; Ishibashi, Masayuki*; Ozaki, Yusuke; Iwatsuki, Teruki
International Journal of Rock Mechanics and Mining Sciences, 144, p.104737_1 - 104737_14, 2021/08
Times Cited Count：4 Percentile：34.69(Engineering, Geological)In this study, we investigated the methodology of modeling for fractured granite around the drift at a depth of 500 m in the Mizunami Underground Laboratory, Japan as a case study. As a result, we developed the fracture modeling method to estimate not only geological parameters of fractures but also hydraulic parameters based on the reproducibility of trace length distribution of fractures. By applying this modeling method, it was possible to construct a Discrete Fracture Network (DFN) model that can accurately reproduce the statistical characteristics of fractures.
Zhao, C.*; Suzudo, Tomoaki; Toyama, Takeshi*; Nishitani, Shigeto*; Inoue, Koji*; Nagai, Yasuyoshi*
Materials Transactions, 62(7), p.929 - 934, 2021/07
Times Cited Count：3 Percentile：25.78(Materials Science, Multidisciplinary)We succeeded in measuring the diffusion coefficient of Cu in Fe in a low temperature range that had not been measured so far. Since the diffusion couple, which is a general method for measuring the diffusion coefficient, can be applied only at high temperature, atom probe tomography and Cu precipitation rate theory were used in this study. The estimated diffusion coefficient was found to be more reliable than that obtained in previous studies. Therefore, it is considered that the estimation by the atom probe provided higher accuracy. Furthermore, the kinetic Monte Carlo simulation revealed that the diffusion coefficient estimated by this method tends to be slightly overestimated as the temperature decreases.
Cs to web-building spiders, 
, and its pathways; A Preliminary study using stable carbon and nitrogen isotope analysesTanaka, Sota; Kakinuma, Hotaru*; Adachi, Taro*; Atarashi-Andoh, Mariko; Koarashi, Jun
Journal of Nuclear Science and Technology, 58(4), p.507 - 514, 2021/04
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Understanding the pathways of Cs transfer to predatory spiders is useful to assess long-term behavior of Cs in the environment, because spiders obtain food resources from both the grazing and detritus food chains in terrestrial-aquatic linking forest ecosystems. In the present study, we collected spider samples at forest interior and riverside. The sample collection was approximately 6.5 years after the FDNPP accident. Moreover, a transfer factor value (T
) for Cs in spiders was quantified. Stable carbon and nitrogen isotope ratios (
C and 
N) of the spiders were also investigated to estimate the transfer pathways of Cs to the spiders.
Hayano, Akira; Ishii, Eiichi
Shigen, Sozai Koenshu (Internet), 5(1), 9 Pages, 2018/03
no abstracts in English
-Iron Using First-Principles-Based Kinetic Monte CarloEbihara, Kenichi; Suzudo, Tomoaki; Yamaguchi, Masatake
Materials Transactions, 58(1), p.26 - 32, 2017/01
Times Cited Count：8 Percentile：38.56(Materials Science, Multidisciplinary)In order to evaluate grain boundary (GB) phosphorous (P) segregation in nuclear reactor pressure vessel steels under irradiation, the rate-theory model based on first-principles calculations is developed. In this study, we evaluated the diffusion coefficient of the mixed interstitial dumbbell of a P atom and an iron(Fe) atom using a kinetic Monte Carlo (kMC) simulation based on first-principles calculations. The evaluated diffusion coefficient was almost the same with the diffusion coefficient of P atoms which migrate via octahedral interstitial sites, and was much faster than that for P transport by vacancies. Furthermore, from the simulation of the irradiation induced GB P segregation using the model which was modified to include P atoms of octahedral interstitial sites, it was found that the boundary condition at GB is not valid for P atoms of octahedral interstitial sites
Saegusa, Hiromitsu; Onoe, Hironori; Ishibashi, Masayuki; Tanaka, Tatsuya*; Abumi, Kensho*; Hashimoto, Shuji*; Bruines, P.*
JAEA-Research 2015-011, 59 Pages, 2015/10
JAEA-Research-2015-011.pdf:49.44MB
It is important to evaluate groundwater flow characteristics on several spatial scales for assessment of long-term safety on geological disposal of high-level radioactive wastes. An estimation of hydraulic heterogeneity caused by fracture network is significant for evaluation of the groundwater flow characteristics in the region of tens of meters square. Heterogeneity of equivalent hydraulic properties is needed to estimate for evaluation of the groundwater flow characteristics in the region of several km square. In order to develop the methodology for multi-scale hydrogeological modeling taking into account the hydraulic heterogeneity, spatial distribution of fractures and their hydraulic properties have been modeled using discrete fracture network (DFN) model. Then, hydrogeological continuum model taking into account the hydraulic heterogeneity has been estimated based on the DFN model. Through this study, the methodology for multi-scale hydrogeological modeling according to type of investigation data has been proposed.
Takeji, Satoru; Tokuda, Shinji; Kurita, Genichi; Suzuki, Takahiro; Isayama, Akihiko; Takechi, Manabu; Oyama, Naoyuki; Fujita, Takaaki; Ide, Shunsuke; Ishida, Shinichi; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 78(5), p.447 - 454, 2002/05
no abstracts in English
Kusama, Yoshinori
Advanced Diagnostics for Magnetic and Inertial Fusion, p.31 - 38, 2002/00
no abstracts in English
Matsumoto, Taro; Tokuda, Shinji; Kishimoto, Yasuaki; Naito, Hiroshi*
Journal of Plasma and Fusion Research SERIES, Vol.5, p.523 - 526, 2002/00
no abstracts in English
; *
JNC TN8400 2001-010, 25 Pages, 2001/03
Performance assessment in geosphere for the JNC's 2nd progress report was based on nuclide migration calculation results by discrete fracture network model. The channel network model approximated from fracture network model with considering fracture connectivity was applied for nuclide migration analysis, since fracture network model had too large data to calculate nuclide migration. However, there are many options in the process of approximation from fracture network model to channel network model. In case of analyzing nuclide migration for above report, so-called "base case", one option was chosen from many options, arbitrarily. In this report, the sensitivity of these options to nuclide migration calculation results was studied. As a result, there was no significant impact to nuclide migration although connectivity of channel and flow characteristics of the model slightly changed among different options. Based on above studies, we concluded that an option used for the base case was appropriate.
Isei, Nobuaki; Sato, Masayasu; Tsuzuki, Kazuhiro; Kawashima, Hisato; Miura, Yukitoshi; Kimura, Haruyuki; JFT-2M Group
Fusion Technology, 39(Part2), p.1101 - 1105, 2001/03
no abstracts in English
Matsumoto, Taro; Tokuda, Shinji; Kishimoto, Yasuaki; Naito, Hiroshi*
Earth Planets and Space, 53(6), p.565 - 570, 2001/00
no abstracts in English
Takeji, Satoru; Tokuda, Shinji; Fujita, Takaaki; Isayama, Akihiko; Ishii, Yasutomo; Kamada, Yutaka; Suzuki, Takahiro; Yoshino, Ryuji; Ide, Shunsuke; Ozeki, Takahisa; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 76(6), p.575 - 584, 2000/06
no abstracts in English
*; *
JNC TJ7400 2000-007, 222 Pages, 2000/03
JNC-TJ7400-2000-007.pdf:13.09MB
no abstracts in English
WILLIAM S.DERSHO*; Yoshizoe, Makoto*
JNC TJ8440 2000-001, 408 Pages, 2000/02
JNC-TJ8440-2000-001.pdf:21.62MB
None
Ueta, Shinzo*; *; *; *
JNC TJ8400 2000-002, 364 Pages, 2000/02
JNC-TJ8400-2000-002.pdf:16.99MB
Japan Nuclear Cycle Development Institute (JNC) have been setting migration parameters and developing its database for the 2nd Progress Report of HLW Geological Disposal (H12 Report). In this study, experimentswere carried out to certify the reliability of parameters and scenario, and examination was carried out to survey procedures of quality management. The main contents are as follows. (1)Data acquisition for certification of migration parameters. The effect of NH
complex of Pd on distribution coefficients (Kd) of Pd on both bentonite and rocks, and the effect of sulfate and carbonate complexes of Am on Kds of Am on bentonite are investigated. Kds of Pd depended on NH
concentration in aqueous. The dependence varied with pH. Effects of sulfate and carbonate complexes on Kds of Am were not remarkable. Apparent diffusivities of Cs in bentonite saturated by saline water were measured. It was confirmed that the apparent diffusivities of Cs in saline water were similar to those in pure water. (2)Evaluation of colloidal effect on nuclide migration. An evaluation of validity of analytical model (Hwang's model) for nuclide migration under existence of colloids and investigation of characterization of colloids in groundwater were carried out. As the results, it was indicated that the Hwang's model was appropriate, and it was found that samplingtechnique influenced concentration and size distribution of colloids. (3)Influence of organic substances on solubility. Solubility of Th was measured under the condition with humic acid and carbonate. It increased roughly in proportion to the concentration of humic acid. And it was remarkably high under the condition with carbonate. It was confirmed that Th solubility data set in H12 report was conservative, even though humic acid existed in groundwater. (4)Use of Mechanistic Models for Safety Assessment. The integrated sorption/diffusion model has been used to calculate K
, D
and D
values ...
