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Yuan, X.*; Hu, Q.*; Lin, X.*; Zhao, C.*; Wang, Q.*; Tachi, Yukio; Fukatsu, Yuta; Hamamoto, Shoichiro*; Siitari-Kauppi, M.*; Li, X.*
Journal of Hydrology, 618, p.129172_1 - 129172_15, 2023/03
Times Cited Count：0 Percentile：0.00(Engineering, Civil)Yamaguchi, Tetsuji; Sawaguchi, Takuma; Tsukada, Manabu; Hoshino, Seiichi*; Tanaka, Tadao
Clay Minerals, 51(2), p.279 - 287, 2016/02
Times Cited Count：7 Percentile：23.95(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.
Minato, Kazuo; Takano, Masahide; Nishi, Tsuyoshi; Ito, Akinori; Akabori, Mitsuo
Recent Advances in Actinide Science, p.317 - 322, 2006/06
To reduce the radiotoxicity of the high-level waste and to use the repository efficiently, recycling of minor actinides (MA: Np, Am, Cm) as well as plutonium is an option for the future nuclear fuel cycle. For MA-bearing fuel development, new facilities with inert atmosphere were installed and the thermal properties of minor actinide compounds, especially nitrides and oxides, were measured. Minor actinide nitrides were prepared by carbothermic reduction of the oxides. Lattice parameter and its thermal expansion were measured by high-temperature X-ray diffraction, and thermal diffusivity by laser flash method.
Taguchi, Tomitsugu; Igawa, Naoki; Jitsukawa, Shiro; Shimura, Kenichiro
Nuclear Instruments and Methods in Physics Research B, 242(1-2), p.469 - 472, 2006/01
Times Cited Count：3 Percentile：28.13(Instruments & Instrumentation)SiC/SiC composites are one of the candidate materials for first wall in a fusion reactor because of their high strength at high temperature and low residual radioactivity after irradiation. In the fusion reactor, these materials are required to have high thermal diffusivity for heat exchange and reducing the thermal shock. Under fusion conditions, helium (He) and hydrogen (H) are produced in SiC. In this study, the effect of He ions implantation on the thermal diffusivities of SiC and SiC/SiC composite were investigated. In the results, the thermal diffusivities of SiC and SiC/SiC composites decreased after He ions implantation. However, the thermal diffusivities of SiC and SiC/SiC composites hardly reduced in the operation temperature of fusion reactor. The thermal diffusivities of He implanted specimens were partly recovered by annealing. The defect concentration induced by He implantation, X
, in SiC/SiC composites was estimated. The X rapidly decreased around 500 
C. The reason is that the He release from SiC starts at 500 C.
Nishi, Tsuyoshi; Takano, Masahide; Ito, Akinori; Akabori, Mitsuo; Minato, Kazuo; Kizaki, Minoru
JAERI-Tech 2005-051, 13 Pages, 2005/09
JAERI-Tech-2005-051.pdf:1.38MB
An apparatus has been developed to measure the thermal diffusivities of minor actinide (MA) compounds. By installing the laser flash apparatus in a glove box with highly purified inert gas atmosphere, the thermal diffusivities measurement of MA compounds of 
-decay nuclides was enabled. A new sample holder has been also developed to measure the thermal diffusivities of very small samples. The performance of this new apparatus was confirmed by measuring the thermal diffusivities of small samples of tantalum, nickel and cerium oxides. The thermal diffusivity values obtained in this work agreed well with the literature values and the values measured by a conventional thermal diffusivities measurement apparatus. Accordingly, this apparatus was found to be useful for thermal diffusivities measurement of MA compounds.
Yamada, Reiji; Igawa, Naoki; Taguchi, Tomitsugu
Journal of Nuclear Materials, 329-333(Part1), p.497 - 501, 2004/08
Times Cited Count：29 Percentile：85.14(Materials Science, Multidisciplinary)SiC fiber reinforced SiC composites (SiC/SiC) have a potential for a structural material for a blanket wall of advanced fusion reactors. To reduce thermal stresses in the wall under heavy thermal loads SiC/SiC composites are expected to have high thermal conductivity as possible. Advanced SiC fibers recently developed, such as Tyranno SA and Hi-Nicalon Type S have been employed for weaving 3D textures as well as those 2D unwoven fabrics. The CVI and PIP/CVI fabrication methods were used. The thermal conductivity at RT was 40-50 W/mK and 35-40 W/mK for Tyranno CVI and PIP/CVI composites, respectively, whereas about 25 and about 17 W/mK at 1000 C. 2D unwoven CVI composites had less than 12 W/mK for RT-1000 C. For Hi-Nicalon Type S, 3D CVI composites had about 35 and about 20 for RT and 1000 C, respectively. The reason of these high thermal conductivities was ascribed to higher density as well as better SiC crystallinity. The fiber configuration effects on the thermal conductivity of SiC/SiC composites were dominant in the low temperature region.
Takeda, Tetsuaki; Iwatsuki, Jin*
Nuclear Technology, 146(1), p.83 - 95, 2004/04
Times Cited Count：12 Percentile：61.35(Nuclear Science & Technology)The objective of this study is to investigate the effect of the existence of hydrogen in a pipe outside on the amount of permeated deuterium through the pipe. It was found that the amount of permeated deuterium decreases with increasing the partial pressure of hydrogen in the pipe outside when the partial pressure of deuterium in the pipe is lower than 100 Pa and that of hydrogen in the pipe outside is higher than 10 kPa. The amount of permeated deuterium on counter permeation was predicted quantitatively by using an effectiveness factor for diffusivity of deuterium in metals and by taking into account the equilibrium state for hydrogen, deuterium and HD molecules on the metal surface. From the results obtained in this study, it is supposed that the amount of tritium transferred from the primary circuit of the HTTR to the hydrogen production system will be reduced by the existence of high-pressure hydrogen in the catalyst pipe of the steam reformer.
Sogabe, Toshiaki; Ishihara, Masahiro; Baba, Shinichi; Tachibana, Yukio; Yamaji, Masatoshi*; Iyoku, Tatsuo; Hoshiya, Taiji*
Materials Science Research International, 9(3), p.235 - 241, 2003/09
2D-C/C composite is one of the promising materials as a next-generation core material in gas-cooled reactors. Effect of air-oxidation on the thermal diffusivity up to 1673K of the 2D-C/C composite was investigated. The C/C composite specimens for measurement of thermal diffusivity were oxidized from 1 to 11 percent weight loss in air at 823K. Thermal diffusivity at room temperature declined 10
20 percent for parallel to lamina direction and 59 percent for that of perpendicular within 11 percent weight loss by oxidation. Thermal diffusivity tended to decrease gradually as the increase of oxidation loss in parallel to lamina, however, it decreased in the beginning of oxidation pretty much and not so changed by further oxidation loss in perpendicular to lamina. Change in thermal conductivity under oxidation condition was also estimated.
in granite matrixYamaguchi, Tetsuji; Nakayama, Shinichi; Kawada, Chiharu*
Genshiryoku Bakkuendo Kenkyu, 9(1), p.61 - 66, 2002/09
The effective diffusivity (
) and distribution ratio (
) of 
Ba in Inada granite have been determined by the through-diffusion method. Experiments were performed in triplicate for 10
, 1 and 10 mol m
BaCl
solutions at 25C. The value obtained at a BaCl concentration of 10 mol m, agreed to the estimated value based on the pore diffusion model. The lower BaCl concentrations yielded higher values and higher values. The variation in was neither due to the speciation of barium in the solutions nor due to variation in physical properties of the pore structure in the rock. Contribution of diffusion in sorbed state should be responsible for the variation in .
Wan, C.*; Motohashi, Yoshinobu*; Shibata, Taiju; Baba, Shinichi; Ishihara, Masahiro; Hoshiya, Taiji
Journal of Iron and Steel Research, International, Special Issue IFAMST, p.85 - 89, 2002/06
no abstracts in English
and (U,Gd)OMinato, Kazuo; Shiratori, Tetsuo; Serizawa, Hiroyuki; Hayashi, Kimio; Une, Katsumi*; Nogita, Kazuhiro*; Hirai, Mutsumi*; Amaya, M.*
Journal of Nuclear Materials, 288(1), p.57 - 65, 2001/01
Times Cited Count：21 Percentile：80.09(Materials Science, Multidisciplinary)no abstracts in English
Iguchi, Tadashi
JAERI-Research 2000-050, 107 Pages, 2000/09
JAERI-Research-2000-050.pdf:4.29MB
no abstracts in English
Yamada, Reiji; Taguchi, Tomitsugu; Igawa, Naoki; Jitsukawa, Shiro
Proceedings of 4th International Energy Agency Workshop on SiCf/SiC Ceramic Composites for Fusion Structural Application, p.33 - 41, 2000/00
no abstracts in English
Shirasu, Yoshiro; Minato, Kazuo
Proc. of the Int. Conf. on Future Nuclear Systems (GLOBAL'99)(CD-ROM), 7 Pages, 1999/00
no abstracts in English
Minato, Kazuo; Shirasu, Yoshiro
Proceedings of 2nd Japanese-Russian Seminar on Technetium, p.77 - 78, 1999/00
no abstracts in English
Takano, Masahide; Minato, Kazuo; Fukuda, Kosaku; Sato, Seichi*; Ohashi, Hiroshi*
Journal of Nuclear Science and Technology, 35(7), p.485 - 493, 1998/07
Times Cited Count：4 Percentile：38.66(Nuclear Science & Technology)no abstracts in English
Minato, Kazuo; Serizawa, Hiroyuki; Fukuda, Kosaku
Journal of Alloys and Compounds, 267, p.274 - 278, 1998/00
Times Cited Count：7 Percentile：49.84(Chemistry, Physical)no abstracts in English
discharges in JT-60UKoide, Yoshihiko; Mori, Masahiro; Fujita, Takaaki; Shirai, Hiroshi; Hatae, Takaki; Takizuka, Tomonori; Kimura, Haruyuki; Oikawa, Toshihiro; Isei, Nobuaki; Isayama, Akihiko; et al.
Plasma Physics and Controlled Fusion, 40(5), p.641 - 645, 1998/00
Times Cited Count：25 Percentile：61.65(Physics, Fluids & Plasmas)no abstracts in English
Minato, Kazuo; Shirasu, Yoshiro
Proc. of 5th Int. Information Exchange Meeting on Actinide and Fission Product Partitioning, p.223 - 230, 1998/00
no abstracts in English
Minato, Kazuo; Serizawa, Hiroyuki; Fukuda, Kosaku; Ito, Mitsuo
JAERI-Research 97-077, 17 Pages, 1997/10
JAERI-Research-97-077.pdf:1.09MB
no abstracts in English
