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Hidaka, Akihide
Nuclear Technology, 208(2), p.318 - 334, 2022/02
Times Cited Count：5 Percentile：65.59(Nuclear Science & Technology)The author previously proposed that the Cs bearing microparticle (Type A) may have been formed by melting and atomization of glass fibers (GF) of the HEPA filter in the SGTS due to flame and blast during the hydrogen explosion in Unit 3. If this hypothesis is correct, the Type A could contain or accompany carbon (C), that ignites spontaneously above 623 K, because of the limited time to be heated up, inclusion of C in the binder applied on the GF surface and closely located charcoal filter. As the previous studies did not focus on C, the present analyses were performed with EPMA whether the Type A contains C. The results showed that the Type A contained C originating from the binder, and non-spherical particles accompanied by the Type A and the film surrounding the Type A contained more C, which is thought to originate from the charcoal filter. These results cannot be explained by the other mechanisms proposed so far, and can be explained consistently by the author proposed hypothesis.
Tamura, Koji*; Toyama, Shinichi
Nihon Genshiryoku Gakkai-Shi ATOMO
, 62(5), p.268 - 271, 2020/05
The laser cutting technology is expected to be a promising candidate for the decommissioning measure of nuclear facilities, because it has a lot of advantage such as its high controllability and excellent suitability to remote handling by robot arm, etcetera. This report describes the recent result from laser cutting technology development for thick steel materials summarizing the cutting demonstration of 300 mm thick steels and dummy pressure vessel, the analysis of cutting condition of thick steel cutting, the observation of cutting process, remote controlled cutting system, the cutting in pile of steels by the system, and countermeasure for fume produce by cutting process.
Shimizu, Kenichi*; Koike, Yuki*; Yamada, Taiki*; Oharada, Kazuya*; Tanaka, Keisuke*; Shobu, Takahisa
Zairyo, 65(9), p.657 - 664, 2016/09
The internal stress in crystalline thermoplastics, polyphenylene sulphide (PPS), reinforced by carbon fibers of 30 mass% was measured by the diffraction method using synchrotron with energy of 12.3 keV. The stress in the matrix was determined by the sin2psi method with side-inclination optics of transmitted X-ray diffractions. Using skin-layer strips cut parallel, perpendicular and 45 degree to the molding direction of the injection molded plates, the matrix stress was measured under the uniaxial applied stress. The experimental values were at least qualitatively agreed with the prediction derived based on micromechanics. The quantitative difference between experiment and prediction is mainly due to the neglect of the distribution of fiber orientations in the micromechanics prediction. These residual stresses were caused by the mismatch of the thermal expansion coefficient between matrix and fibers.
Goniche, M.*; Kazarian, F.*; Bibet, P.*; Maebara, Sunao; Seki, Masami; Ikeda, Yoshitaka; Imai, Tsuyoshi*
Journal of Vacuum Science and Technology A, 23(1), p.55 - 65, 2005/01
Times Cited Count：2 Percentile：9.29(Materials Science, Coatings & Films)Outgassing rates have been measured for long duration (100-4700 seconds) of RF transmission at high power density (50-200 MW/m
) for waveguides made of OFHC copper, dispersoid copper, copper-coated carbon fiber composite and copper-coated graphite. The measurements were performed on multi-waveguide(2 to 8)mockups, using a test bed facility equipped with a 3.7 GHz klystron. The effect on the outgassing rate of waveguide surface temperature and of initial wall gas loading('conditioning'), is examined. It is concluded that an outgassing rate of 1
10
Pam
s
m
and 510 Pamsm at 300
C and 400C respectively, can be expected for the tested material. Based on these measurement results, it is further concluded that no additional pumping will be needed for the LHRF antenna proposed for ITER.
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.
Sogabe, Toshiaki; Ishihara, Masahiro; Baba, Shinichi; Kojima, Takao; Tachibana, Yukio; Iyoku, Tatsuo; Hoshiya, Taiji; Hiraoka, Toshiharu*; Yamaji, Masatoshi*
JAERI-Research 2002-026, 22 Pages, 2002/11
JAERI-Research-2002-026.pdf:2.41MB
Carbon Fiber Reinforced Carbon-carbon Composites, C/C composites, have been developed and extensively studied their characteristics. C/C composites are considered to be promising materials for the application of a control rod in the next high performance high temperature gas-cooled reactors. In the present paper, details of the development of the candidate C/C composite are described. In the course of the development of the material, especially, feasibility of the production, stableness of the supply and cost are much taken into consideration. As the physical properties of the material, high mechanical strength such as tensile and bending, high fracture strain and fracture toughness and low dimensional change by neutron irradiation have to be met. The developed 2D-C/C composite consists of plain-weave PAN-based carbon fiber cloth and pitch derived matrix. Also, high purification up to the level of nuclear grade was successfully attained in the composite.
Masaki, Kei; Taniguchi, Masaki; Miyo, Yasuhiko; Sakurai, Shinji; Sato, Kazuyoshi; Ezato, Koichiro; Tamai, Hiroshi; Sakasai, Akira; Matsukawa, Makoto; Ishida, Shinichi; et al.
Fusion Engineering and Design, 61-62, p.171 - 176, 2002/11
Times Cited Count：19 Percentile：74.77(Nuclear Science & Technology)A flat carbon fiber composite tile mock-up with screw tubes, which have helical fins like a nut, was fabricated aiming at further improvement of the heat removal performance of the cost-effectively manufactured divertor target for JT-60SC (modified JT-60 as a superconducting coil tokamak). The heat removal performance of the mock-up was successfully demonstrated on the JAERI Electron Beam Irradiation Stand. The estimated heat transfer coefficient of the screw tube at the non-boiling region was roughly 3 times higher than that of the smooth tube. This corresponds to 1.5 times that of the swirl tube. A heat cycle test of 10 MW/m2 showed that the mock-up with the screw tubes could withstand for 1400 cycles. These results indicate that the divertor target plate with the flat carbon fiber composite tile and the screw tube can be a promising candidate for the JT-60SC divertor target.
Ishihara, Masahiro; Kojima, Takao; Hoshiya, Taiji
Proceedings of International Conference on Carbon in 2002 (Carbon2002) (CD-ROM), 6 Pages, 2002/00
Bending failure of two-dimensional C/C composite was studied by both experimental and analytical approaches. In the experiment, a bending test and observation of failure surfaces were performed. From the surface observation, three kinds of fundamental fracture modes were observed; these were tensile, compressive and shear fracture modes. In the analysis, the risk-based statistical fracture theory, so-called the competing risk theory was applied to clarify the bending failure taking account of the competition of these fracture modes. Parameters used in the theory on these fundamental fracture modes were determined by additional experiments, and the theory was applied to the bending failure prediction. As a result of this study, it is concluded that the bending failure was well predicted by the theory, and that the theory would be possible to predict the strength under stress gradient condition. Furthermore, a new strength prediction method combined with FEM code, which is applicable to arbitrary shaped structures with stress gradient, was proposed in this paper.
Oshima, Akihiro; Udagawa, Akira; Morita, Yosuke
Radiation Physics and Chemistry, 60(4-5), p.467 - 471, 2001/03
Times Cited Count：12 Percentile：64.73(Chemistry, Physical)Plain-woven carbon fber-filled polytetrafluoroethylene (PTFE)composites were fabricated by radiation-crosslinking under selective conditions.High mechanical and frictional properties are found in the composite materials compared with crosslinked PTFE without fiber.The composite materials with optional shapes,which are laminated after electron beam (EB) crosslinking treatment of each mono-layer could also be fabricated.
Oshima, Akihiro; Udagawa, Akira; Morita, Yosuke
Radiation Physics and Chemistry, 60(1-2), p.95 - 100, 2001/01
Times Cited Count：8 Percentile：52.36(Chemistry, Physical)no abstracts in English
Oshima, Akihiro; Udagawa, Akira; Morita, Yosuke
Proceedings of International Symposium on Prospect for Application of Radiation towards the 21st Century, p.83 - 84, 2000/00
no abstracts in English
*; Udagawa, Akira; Morita, Yosuke
Conference Proceeding RadTech Asia'99, p.507 - 512, 1999/08
no abstracts in English
Oku, Tatsuo*; Kurumada, Akira*; McEnaney, B.*; Burchell, T. D.*; Ishihara, Masahiro; Hayashi, Kimio; Baba, Shinichi; Aihara, Jun
Proceedings of 1st World Conference of Carbon (EUROCARBON 2000), 1, p.947 - 947, 1999/07
no abstracts in English
; *; Araki, Masanori; Nakamura, Kazuyuki; Akiba, Masato
Journal of Nuclear Materials, 258-263, p.318 - 322, 1998/00
Times Cited Count：8 Percentile：57.28(Materials Science, Multidisciplinary)no abstracts in English
Fujii, Kimio; Yamada, Reiji
Journal of Nuclear Materials, 258-263, p.1953 - 1959, 1998/00
Times Cited Count：8 Percentile：57.28(Materials Science, Multidisciplinary)no abstracts in English
C-carbon fiber composite ceramics as plasma facing materials in nuclear fusion reactor, 3; Heat resistance evaluation by electron beam irradiation and by in situ plasma discharge in JT-60Jimbo, Ryutaro*; Saido, Masahiro; Nakamura, Kazuyuki; Akiba, Masato; ; Dairaku, Masayuki; *; *; *; *
Journal of the Ceramic Society of Japan, International Edition, 105, p.1179 - 1187, 1997/00
no abstracts in English
Nakamura, Kazuyuki; *; Dairaku, Masayuki; Akiba, Masato; Araki, Masanori; Okumura, Yoshikazu
Journal of Nuclear Materials, 220-222, p.890 - 894, 1995/00
Times Cited Count：19 Percentile：84.39(Materials Science, Multidisciplinary)no abstracts in English
; Kajimoto, Yoichi; ; Endo, Akira; Ikezawa, Yoshio
Hoken Butsuri, 29, p.189 - 194, 1994/00
no abstracts in English
Sato, Kazuyoshi; Akiba, Masato; Araki, Masanori; ; ; I.Smid*; A.Cardella*; R.Duwe*; E.D.Pietro*
JAERI-M 93-058, 22 Pages, 1993/03
no abstracts in English
Ando, Toshiro; Takatsu, Hideyuki; Nakamura, Hiroo; Yamamoto, Masahiro; ; Arai, Takashi; Kaminaga, Atsushi; ; Horiike, Hiroshi; Shimizu, Masatsugu; et al.
Kaku Yugo Kenkyu, 65(SPECIAL ISSUE), p.27 - 49, 1991/03
no abstracts in English
; ; ; ; *
Hoken Butsuri, 21, p.9 - 15, 1986/00
no abstracts in English
