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Sumita, Junya; Shibata, Taiju; Fujita, Ichiro*; Kunimoto, Eiji*; Yamaji, Masatoshi*; Eto, Motokuni*; Konishi, Takashi*; Sawa, Kazuhiro
Nuclear Engineering and Design, 271, p.314 - 317, 2014/05
Times Cited Count：11 Percentile：64.59(Nuclear Science & Technology)In this study, in order to develop evaluation method for material properties and to evaluate the irradiation-induced property changes under higher neutron doses for IG-430, the oxidation and densification effects on elastic modulus of IG-430 were investigated. Moreover, the correlation of the microstructure based on the X-ray tomography images and the material properties was discussed. It was shown that the elastic modulus of the densified graphite depends on only the closed pores and it is possible to evaluate the material properties of graphite by using X-ray tomography method. However, it is necessary to take into account of the change in the number and shape of closed pores in the grain to simulate the elastic modulus of the highly oxidized and irradiated materials by the homogenization analysis.
Sumita, Junya; Shibata, Taiju; Fujita, Ichiro*; Kunimoto, Eiji*; Yamaji, Masatoshi*; Eto, Motokuni*; Konishi, Takashi*; Sawa, Kazuhiro
Proceedings of 6th International Topical Meeting on High Temperature Reactor Technology (HTR 2012) (USB Flash Drive), 6 Pages, 2012/10
In this study, in order to develop evaluation method for material properties and to evaluate the irradiation-induced property changes under higher neutron doses for IG-430, the oxidation and densification effects on elastic modulus of IG-430 were investigated. Moreover, the correlation of the microstructure based on the X-ray tomography images and the material properties was discussed. It was shown that the elastic modulus of the densified graphite depends on only the closed pores and it is possible to evaluate the material properties of graphite by using X-ray tomography method. However, it is necessary to take into account of the change in the number and shape of closed pores in the grain to simulate the elastic modulus of the highly oxidized and irradiated materials by the homogenization analysis.
Sumita, Junya; Shibata, Taiju; Kunimoto, Eiji*; Yamaji, Masatoshi*; Konishi, Takashi*; Sawa, Kazuhiro
IOP Conference Series; Materials Science and Engineering, 18(16), p.162012_1 - 162012_4, 2011/09
Times Cited Count：1 Percentile：52.78(Materials Science, Ceramics)For control rod element of Very High Temperature Reactor, carbon fiber reinforced carbon matrix composite (C/C composite) is one of the major candidate materials for its high strength and thermal stability. The development of a property prediction model of the two-dimensional (2D)-C/C composite is one of the most important subjects for the design methodology for control rod. Since the property of the 2D-C/C composite is strongly dependent on its microstructure, fiber/matrix, it would be possible to evaluate the properties of the 2D-C/C composite from its microstructure. In this study, in order to develop the property prediction model of the 2D-C/C composite base on its microstructure, pore distribution was investigated by using the X-ray computed tomography (X-ray CT) images and developed image based voxcel model. The compressive strength of the 2D-C/C composite was measured and evaluated by the voxcel model. This study shows that the pore distribution in the 2D-C/C composite can be confirmed visually and the volume and shape of the pores can be estimated from X-ray CT images. It is also shown that evaluation of the compressive strength by using the voxel model is useful to simulate the trend of the stress distribution of the 2D-C/C composite. However, it is necessary to characterize the property of the 2D-C/C composite and to set up the appropriate mesh to simulate the absolute stress value precisely.
Sumita, Junya; Shibata, Taiju; Kunimoto, Eiji*; Yamaji, Masatoshi*; Konishi, Takashi*; Sawa, Kazuhiro
Journal of Nuclear Science and Technology, 47(4), p.411 - 420, 2010/04
Times Cited Count：4 Percentile：30.63(Nuclear Science & Technology)Two dimensional carbon fiber reinforced carbon composite (2D-C/C composite) is one of the candidate materials for a reactor internals, e.g. control rod element, of Very High Temperature Reactor (VHTR) because of its high strength at high temperature and thermal stability. From the viewpoint of its application to the reactor internals of VHTR, it is important to investigate the anisotropy effect on its properties for the design and safety analysis of VHTR. Moreover, the property of 2D-C/C composite is strongly related to its microstructure, therefore, it is necessary to observe the internal microstructure to investigate the relationship between the microstructural change and the property change. This study has shown that the X-ray tomography could be applied to observe the microstructural change of thermally 2D-C/C composite. The relationship between the thermal conductivity and the coefficient of thermal expansion (CTE) change and burn-off of thermally oxidized 2D-C/C composite could be expressed by the empirical exponential decay formula in both directions perpendicular and parallel to lamina. It could be explained the direction of hexagonal graphite crystal structure from carbon atoms and microstructural change of 2D-C/C composite.
Matsuda, Takeshi*; Noda, Masaru*; Iriya, Keishiro*; Konishi, Kazuhiro*; Nakayama, Masashi; Kobayashi, Yasushi
JAEA-Research 2007-089, 139 Pages, 2008/05
JAEA-Research-2007-089.pdf:13.57MB
In Horonobe Underground Research Center construction of underground facility began in 2005 and construction practicality test with HFSC (Highly Fly-ash contained Silica-fume Cement) is planned in a part of the gallery. Before the HFSC will be contracted in the gallery it is necessary to check that the HFSC has performance under the actual construction. The main work of this Japanese fiscal year is making a detailed test plan for the HSFC construction practicality, that is scheduled after 2007 and laboratory tests on lowering behavior of pH in the HFSC concrete were conducted. On the construction practicality test with low alkaline concrete, HFSC in-situ experiment plan was studied in case using HSFC424N as shotcrete. The aims of the in-situ test are the validation in applicability of low alkaline concrete as a support member for underground opening in the realistic geological environment and building the method to evaluate influence to the surrounding geological environment. The location of the in-situ test is in the connection tunnel of a depth of 140m and the geology is the Koetoi formation. The period of the test is approximately 10 years. The test plan was designed to be able to make a comparison with Ordinary Portland Cement. As it is necessary to confirm the strength property of the HFSC concrete with materials procured at construction site, strength of the base concrete using local procured fine aggregate and coarse aggregate based on the result of the selection of mix proportion in 2005 research was checked. On laboratory tests on lowering behavior of pH in HFSC concrete, the pH of immersion fluid was measured and components of the immersion fluid and the solid phase were analyzed using test specimens in a long-term immersion test which had been continued since 2005.
Takeda, Nobufumi*; Iriya, Keishiro*; Hitomi, Takashi*; Konishi, Kazuhiro*; Kurihara, Yuji*
Obayashigumi Gijutsu Kenkyushoho (CD-ROM), (72), 8 Pages, 2008/00
To evaluate applicability as the steel reinforced concrete of the concrete with the low alkalinity cement which contains pozzolan that has been examined to apply for high level radioactive waste disposals, concrete of 30% water-cement ratio was performed 6-year marine exposure examination, aging of their compressive strength, the intrusion width of the chloride ion and the corrosion of reinforcing bar were investigated. And based on these results, progress of corrosion of reinforcing bar and the outbreak time of reinforcing corrosion crack were predicted. As a result, the following result became clear. (1) There is no fall of the compressive strength of test pieces in 6-year marine exposure examination. (2) There is little penetration of the chloride ion in comparison with the concrete consists of ordinary Portland cement. (3) The corrosion of reinforcing bar starts for the early stage with a little quantity of chloride ion intrusion, the progress until six years is extremely small. (4) the corrosion speed of the reinforcing bar of concrete with low alkali cement in underground water including sea water were estimated as 0.30
0.55 mg/(cm
year). In case of using this concrete to structure with 100 mm cover thickness and 22 mm reinforcing bar diameter, the outbreak time of reinforcing corrosion crack were predicted as 50100 years after construction.
Miura, Norihiko*; Konishi, Kazuhiro*; Iriya, Keishiro*; Nakayama, Masashi; Matsui, Hiroya
Semento, Konkurito, (728), p.63 - 67, 2007/10
High level radioactive waste(HLW) repository is to be constructed at depth of over 300m below the surface. Shotcrete and lining will be used for safety under construction and operational period. Concrete is a kind of composite material which is constituted by aggregate, cement and additives. Low alkaline cement has been developed from the viewpoint of long term stability of the barrier systems which would be influenced by high alkaline arising from cement material. Japan Atomic Energy Agency(JAEA) has been developed HFSC(Highly Fly-ash contained Silica-fume Cement) which is one of a low alkaline cement contained silica-fume and fly-ash. JAEA is now implementing the construction of the underground research laboratory(URL) at Horonobe for the purpose of research in deep geological science and repository engineering technology. This report shows the properties of HFSC using as shotcrete.
Kobayashi, Yasushi; Yamada, Tsutomu; Nakayama, Masashi; Matsui, Hiroya; Matsuda, Takeshi*; Konishi, Kazuhiro*; Iriya, Keishiro*; Noda, Masaru*
JAEA-Review 2007-007, 42 Pages, 2007/03
JAEA-Review-2007-007.pdf:3.12MB
Shotcrete and lining will be used for safety under construction and operational period in HLW repository. Concrete is a kind of composite material which is constituted by aggregate, cement and other mixture. Low alkaline cement has been developed from the viewpoint of long term stability of the barrier systems which would be influenced by high alkaline arising from cement material. HFSC is one of a low alkaline cement. It has been developed in Japan Atomic Energy Agency. JAEA are now implementing the construction of the under ground research laboratory (URL) at Horonobe. This report shows the in situ test plan for shotcrete using HFSC at Horonobe URL with identifying requirements for cement materials to be used in HLW repository, and also reviews major literatures of low alkaline cement. This in situ test plan is aiming to assess the performance of HFSC shotcrete in terms of mechanics, workability, durability, and so on.
Konishi, Kazuhiro; Nakayama, Masashi; Mihara, Morihiro; Yoshida, Yasushi*; Iriya, Keishiro*; Akiyoshi, Kenji*; Noda, Masaru*
JAEA-Research 2006-040, 53 Pages, 2006/06
JAEA-Research-2006-040.pdf:12.6MB
no abstracts in English
Aoyanagi, Shigeo; Yui, Mikazu; Tanai, Kenji; Kawakami, Susumu; Fujita, Tomoo; Taniguchi, Naoki; Shibata, Masahiro; Konishi, Kazuhiro; Nishimura, Mayuka; Kikuchi, Hirohito*; et al.
JAEA-Review 2006-014, 61 Pages, 2006/03
JAEA-Review-2006-014.pdf:5.03MB
no abstracts in English
Isobe, Kanetsugu; Nakamura, Hirofumi; Kaminaga, Atsushi; Tsuzuki, Kazuhiro; Higashijima, Satoru; Nishi, Masataka; Kobayashi, Yasunori*; Konishi, Satoshi*
Fusion Engineering and Design, 81(1-7), p.827 - 832, 2006/02
Times Cited Count：11 Percentile：60.27(Nuclear Science & Technology)Exhaust gas from JT-60U during experimental operation has been measured with Gas Chromatography (GC), and the gas exhaust characteristic from JT-60U on plasma discharge conditions has been investigated during the JT-60U experimental campaign in 2003-2004. During experimental operation of JT-60U, hydrogen isotope concentration strongly depended on the type of discharges such as high performance, long pulse and so on. On the other hand, impurity species, such as helium, hydrocarbon and carbon oxide, were detected during plasma discharges occasionally. During the experimental operation, plasma disruption remarkably tended to produce high concentration impurities. Glow discharge and Taylor discharge for wall conditioning also produced impurities. In the case of normal plasma, impurity was detected and high performance plasma, such as high 
plasma, tended to produce high concentration impurities. This result indicated that impurities concentration might be higher in the case of normal plasma in ITER, because of its high performance.
Iriya, Keishiro*; Nakayama, Masashi; Konishi, Kazuhiro; Mihara, Morihiro
Konkurito Kogaku Nenji Rombunshu (DVD-ROM), 28(1), p.173 - 178, 2006/00
no abstracts in English
Hayashi, Takumi; Kobayashi, Kazuhiro; Iwai, Yasunori; Yamada, Masayuki; Suzuki, Takumi; Ohira, Shigeru; Nakamura, Hirofumi; Shu, W.; Yamanishi, Toshihiko; Kawamura, Yoshinori; et al.
Fusion Engineering and Design, 51-52(Part.B), p.543 - 548, 2000/11
Times Cited Count：19 Percentile：74.85(Nuclear Science & Technology)no abstracts in English
Nishi, Masataka; Yamanishi, Toshihiko; Kawamura, Yoshinori; Iwai, Yasunori; Isobe, Kanetsugu; Ohira, Shigeru; Hayashi, Takumi; Nakamura, Hirofumi; Kobayashi, Kazuhiro; Suzuki, Takumi; et al.
Fusion Engineering and Design, 49-50, p.879 - 883, 2000/11
Times Cited Count：4 Percentile：32.52(Nuclear Science & Technology)no abstracts in English
Ohira, Shigeru; Hayashi, Takumi; Nakamura, Hirofumi; Kobayashi, Kazuhiro; Tadokoro, Takahiro*; Nakamura, H.*; Ito, Takeshi*; Yamanishi, Toshihiko; Kawamura, Yoshinori; Iwai, Yasunori; et al.
Nuclear Fusion, 40(3Y), p.519 - 525, 2000/03
Times Cited Count：24 Percentile：59.01(Physics, Fluids & Plasmas)no abstracts in English
Yamanishi, Toshihiko; Kawamura, Yoshinori; Iwai, Yasunori; Arita, Tadaaki*; Maruyama, T.*; Kakuta, Toshiya*; Konishi, Satoshi; Enoeda, Mikio; Ohira, Shigeru; Hayashi, Takumi; et al.
Nuclear Fusion, 40(3Y), p.515 - 518, 2000/03
Times Cited Count：6 Percentile：21.01(Physics, Fluids & Plasmas)no abstracts in English
Yamanishi, Toshihiko; Konishi, Satoshi; Hayashi, Takumi; Kawamura, Yoshinori; Iwai, Yasunori; Maruyama, T.*; Kakuta, Toshiya*; Ohira, Shigeru; Nakamura, Hirofumi; Kobayashi, Kazuhiro; et al.
Fusion Technology, 34(3), p.536 - 540, 1998/11
no abstracts in English
Ohira, Shigeru; Hayashi, Takumi; Nakamura, Hirofumi; Kobayashi, Kazuhiro; Tadokoro, Takahiro*; Nakamura, H.*; Ito, Takeshi*; Yamanishi, Toshihiko; Kawamura, Yoshinori; Iwai, Yasunori; et al.
Fusion Energy 1998, 3, p.1069 - 1072, 1998/10
no abstracts in English
Okuno, Kenji; Konishi, Satoshi; Yamanishi, Toshihiko; Ohira, Shigeru; Enoeda, Mikio; Nakamura, Hirofumi; Iwai, Yasunori; Hayashi, Takumi; Kawamura, Yoshinori; Kobayashi, Kazuhiro
Fusion Technology 1996, p.1277 - 1280, 1997/00
no abstracts in English
Hayashi, Takumi; Konishi, Satoshi; Ohira, Shigeru; Nakamura, Hirofumi; Inoue, Masahiko*; Watanabe, Tetsuo*; Hirata, Kazuhiro*; Naruse, Yuji; Okuno, Kenji; Barnes, J. W.*; et al.
JAERI-M 93-094, 54 Pages, 1993/03
no abstracts in English
