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Journal Articles

Applicability study of nuclear graphite material IG-430 to VHTR

Osaki, Hirotaka; Shimazaki, Yosuke; Sumita, Junya; Shibata, Taiju; Konishi, Takashi; Ishihara, Masahiro

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 8 Pages, 2015/05

For the design on the VHTR graphite components, it is desirable to employ graphite material with higher strength. IG-430 graphite has been developed as an advanced candidate for VHTR. However, the new developed IG-430 does not have enough databases for the design of HTGR. In this paper, the compressive strength (Cs) of IG-430, one of important strengths for design data, is statistically evaluated. The component reliability is evaluated based on the safety factors defined by the graphite design code, and the applicability as the VHTR graphite material is discussed. It was found that IG-430 has higher strength (about 11%) and lower standard deviation (about 27%) than IG-110 which is one of traditional graphites used for HTGR, because the crack in IG-430 would not easy to propagate rather than IG-110. Since fracture probability for IG-430 is low, the higher reliability of core-component will be achieved using IG-430. It is expected that IG-430 is applicable for VHTR graphite material.

Journal Articles

Compatibility of Ni and F82H with liquid Pb-Li under rotating flow

Kanai, Akihiko*; Park, C.*; Noborio, Kazuyuki*; Kasada, Ryuta*; Konishi, Satoshi*; Hirose, Takanori; Nozawa, Takashi; Tanigawa, Hiroyasu

Fusion Engineering and Design, 89(7-8), p.1653 - 1657, 2014/10

 Times Cited Count:4 Percentile:69.35(Nuclear Science & Technology)

Journal Articles

Development of evaluation method with X-ray tomography for material property of IG-430 graphite for VHTR/HTGR

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:7 Percentile:46.7(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.

JAEA Reports

Evaluation of oxidation characteristics of fine-grained graphites (IG-110 and IG-430) for very high temperature reactor; Changes in density distribution and compressive strength caused by air-oxidation

Fujita, Ichiro*; Eto, Motokuni*; Osaki, Hirotaka; Shibata, Taiju; Sumita, Junya; Konishi, Takashi; Yamaji, Masatoshi; Kunimoto, Eiji

JAEA-Research 2013-004, 20 Pages, 2013/07

JAEA-Research-2013-004.pdf:2.4MB

Graphite components in HTGR and VHTR may be oxidized by impurities in coolant helium-gas even at normal operation, as well as by air at air-ingress accident. In this study, by air-oxidation test at 520-900$$^{circ}$$C, oxidation characteristics of IG-110 and IG-430 graphites, and associated decrease in compressive strength were examined. The following results were obtained. (1) The activation energy of the air-oxidation for IG-430 is 176 kJ/mol being almost same as for IG-110, though the oxidation rate for IG-430 is less than a half of that for IG-110. (2) There are correlations between density change and decrease in compressive strength. Decrease in strength is the largest in case that the oxidation temperature is lower than 600 $$^{circ}$$C where the homogenous oxidation occurs. (3) In the process of oxidation, amorphous binder regions are predominantly oxidized. It suggests that peeling-off of cokes grains is necessary to be considered for oxidation weight loss, as well as gasification.

Journal Articles

Development of evaluation method with X-ray tomography for material property of IG-430 graphite for VHTR/HTGR

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.

Journal Articles

Correlation of microstructure and compressive strength of C/C composite using X-ray tomography

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:40.02

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.

Journal Articles

Research and developments on application of carbon-carbon composite to HTGR/VHTR in Japan

Eto, Motokuni*; Konishi, Takashi*; Shibata, Taiju; Sumita, Junya

IOP Conference Series; Materials Science and Engineering, 18(16), p.162003_1 - 162003_6, 2011/09

 Times Cited Count:2 Percentile:21.22

High Temperature Gas-cooled Reactor (HTGR) and Very High Temperature Reactor (VHTR) are attractive nuclear reactors to obtain high temperature helium gas to the reactor outlet. To enhance the thermal efficiency, the core internals of HTGR/VHTR are subjected to the very severe high temperature condition. The carbon fiber reinforced carbon-carbon composite (C/C composite) is one of the advanced material candidates for the control rod sheath of the reactors because of its excellent thermal resistance and stability in the severe condition. The R&Ds on the C/C composite application to HTGR have been carried out since 1990'. JAEA and Toyo Tanso have been in collaboration with each other in the R&Ds. The development of control rod made of C/C composite is recently focused as one of the important subjects to develop the VHTR in the international R&Ds. The scheme of the development of JAEA is categorized as the following phases; (1) Database establishment, (2) Design and manufacturing of component and (3) Demonstration test by HTTR. At the initial stage of the development in 1990' in JAERI, the feasibility of the control rod using C/C composite was demonstrated by a conceptual design. The phase (2) is planned to be completed within 5 years. This paper presents the review of the development of the control rod made of C/C composite and the recent R&D results.

Journal Articles

Thickness and density of additive adsorbed layer on metal surface measured by neutron reflectometry and its effect on tribological properties

Hirayama, Tomoko*; Torii, Takashi*; Konishi, Yohei*; Maeda, Masayuki*; Matsuoka, Takashi*; Inoue, Kazuko*; Hino, Masahiro*; Yamazaki, Dai; Takeda, Masayasu

Nippon Kikai Gakkai Rombunshu, C, 77(779), p.2884 - 2893, 2011/07

Journal Articles

Multiplet scattering approach to XAS for Co-C$$_{60}$$ films

Hojo, Ikuko*; Matsumoto, Yoshihiro; Maruyama, Takashi*; Nagamatsu, Shinichi*; Entani, Shiro; Sakai, Seiji; Konishi, Takehisa*; Fujikawa, Takashi*

Photon Factory News, 29(1), p.20 - 25, 2011/05

no abstracts in English

Journal Articles

Surface study of organopalladium molecules on S-terminated GaAs

Konishi, Tomoya*; Nishiwaki, Nagatoshi*; Tojo, Takashi*; Ishikawa, Takuma*; Teraoka, Teruki*; Ueta, Yukiko*; Kihara, Yoshifumi*; Moritoki, Hideji*; Tono, Tatsuo*; Musashi, Mio*; et al.

Physica Status Solidi (C), 8(2), p.405 - 407, 2011/02

 Times Cited Count:3 Percentile:21.34

Journal Articles

Investigation of microstructural change by X-ray tomography and anisotropic effect on thermal property of thermally oxidized 2D-C/C composite for Very High Temperature Reactor

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:65.91(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.

Journal Articles

Prediction of crack due to corrosion of reinforcing bar in low alkali concrete

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$$sim$$0.55 mg/(cm$$^{2}$$ 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 50$$sim$$100 years after construction.

Journal Articles

Research and development of nuclear fusion

Ushigusa, Kenkichi; Seki, Masahiro; Ninomiya, Hiromasa; Norimatsu, Takayoshi*; Kamada, Yutaka; Mori, Masahiro; Okuno, Kiyoshi; Shibanuma, Kiyoshi; Inoue, Takashi; Sakamoto, Keishi; et al.

Genshiryoku Handobukku, p.906 - 1029, 2007/11

no abstracts in English

Journal Articles

Introduction to plasma fusion energy

Takamura, Shuichi*; Kado, Shinichiro*; Fujii, Takashi*; Fujiyama, Hiroshi*; Takabe, Hideaki*; Adachi, Kazuo*; Morimiya, Osamu*; Fujimori, Naoji*; Watanabe, Takayuki*; Hayashi, Yasuaki*; et al.

Kara Zukai, Purazuma Enerugi No Subete, P. 164, 2007/03

no abstracts in English

JAEA Reports

Analysis of exhaust gas composition in JT-60U discharge cleaning experiments

Horikawa, Toyohiko*; Kaminaga, Atsushi; Nakamura, Hirofumi; Higashijima, Satoru; Arai, Takashi; Kubo, Hirotaka; Konishi, Satoshi*; Nishikawa, Masabumi*

JAERI-Tech 2003-082, 66 Pages, 2003/12

JAERI-Tech-2003-082.pdf:3.44MB

no abstracts in English

Journal Articles

Design and technology development of solid breeder blanket cooled by supercritical water in Japan

Enoeda, Mikio; Kosaku, Yasuo; Hatano, Toshihisa; Kuroda, Toshimasa*; Miki, Nobuharu*; Homma, Takashi; Akiba, Masato; Konishi, Satoshi; Nakamura, Hirofumi; Kawamura, Yoshinori; et al.

Nuclear Fusion, 43(12), p.1837 - 1844, 2003/12

 Times Cited Count:96 Percentile:5.7(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Fusion reactor design towards radwaste minimum with advanced shield material

Tobita, Kenji; Konishi, Satoshi; Nishio, Satoshi; Kosako, Kazuaki*; Tabara, Takashi*

Purazuma, Kaku Yugo Gakkai-Shi, 77(10), p.1035 - 1039, 2001/10

no abstracts in English

Journal Articles

Fusion reactor technology; Challenge to future energy

Seki, Masahiro; Hishinuma, Akimichi; Kurihara, Kenichi; Akiba, Masato; Abe, Tetsuya; Ishitsuka, Etsuo; Imai, Tsuyoshi; Enoeda, Mikio; Ohira, Shigeru; Okumura, Yoshikazu; et al.

Kaku Yugoro Kogaku Gairon; Mirai Enerugi Eno Chosen, 246 Pages, 2001/09

no abstracts in English

JAEA Reports

Effect of coarse-grains on strength and fracture toughness of fine-grained graphite

Takahashi, Tsuneo*; Ishihara, Masahiro; Baba, Shinichi; Arai, Taketoshi; Hayashi, Kimio; Konishi, Takashi*

JAERI-Research 2001-005, 62 Pages, 2001/03

JAERI-Research-2001-005.pdf:6.8MB

no abstracts in English

JAEA Reports

Fundamental Research of Two-Phase Flows with High Liquid/Gas Density Ratios

Mishima, Kaichiro*; Hibiki, Takashi*; Saito, Yasushi*; Tobita, Yoshiharu; Konishi, Kensuke; Suzuki, Toru

JNC-TY9400 2000-018, 72 Pages, 2000/07

JNC-TY9400-2000-018.pdf:3.92MB

no abstracts in English

45 (Records 1-20 displayed on this page)