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Kawano, Takahiro*; Mizuta, Naoki; Ueta, Shohei; Tachibana, Yukio; Yoshida, Katsumi*
JAEA-Technology 2023-014, 37 Pages, 2023/08
JAEA-Technology-2023-014.pdf:2.35MB
Fuel compact for High Temperature Gas-cooled Reactor (HTGR) is fabricated by calcinating a matrix consisting of graphite and binder with the coated fuel particle. The SiC-matrixed fuel compact uses a new matrix made of silicon carbide (SiC) replacing the conventional graphite. Applying the SiC-matrixed fuel compact for HTGRs is expected to improve their performance such as power densities. In this study, the sintering conditions for applying SiC as the matrix of fuel compacts for HTGR are selected, and the density and thermal conductivity of the prototype SiC are measured.
Okita, Shoichiro; Mizuta, Naoki; Takamatsu, Kuniyoshi; Goto, Minoru; Yoshida, Katsumi*; Nishimura, Yosuke*; Okamoto, Koji*
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 10 Pages, 2023/05
Yamada, Susumu; Machida, Masahiko; Tanaka, Minori*; Seki, Katsumi*; Arikawa, Taro*
Nihon Oyo Suri Gakkai Rombunshi, 31(1), p.20 - 43, 2021/03
no abstracts in English
Katsumi, Toshiyuki; Yoshida, Yasuhito*; Nakagawa, Ryo*; Yazawa, Shinya*; Kumada, Masashi*; Sato, Daisuke*; Thwe Thwe, A.; Chaumeix, N.*; Kadowaki, Satoshi
Journal of Thermal Science and Technology (Internet), 16(2), p.21-00044_1 - 21-00044_13, 2021/00
Times Cited Count：5 Percentile：36.79(Thermodynamics)The effects of addition of CO
and water vapor on characteristics of dynamic behavior of hydrogen/air premixed flames were elucidated experimentally. By Schlieren photography, wrinkles on the flame surface were clearly observed in low equivalence ratios. The propagation velocity increased monotonically as the flame radius became larger and flame acceleration was found. Increasing the addition of inert gas, the propagation velocity decreased, especially in the case of CO addition. Moreover, the Markstein length and the wrinkling factor decreased. This indicated that the addition of Co or HO promoted the unstable motion of hydrogen flames, which could be due to the enhancement of the diffusive-thermal effect. Based on the characteristics of dynamic behavior of hydrogen flames, the parameters used in the mathematical model on propagation velocity including flame acceleration was obtained, and then the flame propagation velocity under various conditions was predicted.
Kobayashi, Tatsuya*; Ito, Kimitaka*; Ido, Takeshi*; Kamiya, Kensaku*; Ito, Sanae*; Miura, Yukitoshi; Nagashima, Yoshihiko*; Fujisawa, Akihide*; Inagaki, Shigeru*; Ida, Katsumi*
Scientific Reports (Internet), 7(1), p.14971_1 - 14971_8, 2017/11
Times Cited Count：22 Percentile：78.98(Multidisciplinary Sciences)Kobayashi, Tatsuya*; Ito, Kimitaka*; Ido, Takeshi*; Kamiya, Kensaku; Ito, Sanae*; Miura, Yukitoshi; Nagashima, Yoshihiko*; Fujisawa, Akihide*; Inagaki, Shigeru*; Ida, Katsumi*; et al.
Scientific Reports (Internet), 6, p.30720_1 - 30720_7, 2016/08
Times Cited Count：13 Percentile：64.47(Multidisciplinary Sciences)In this Letter, we report model verifications for a key physics for the L-H transition. Radial electric field excitation, using discharges having a two-step transition. Examining time derivative of Poissons equation, it is found that the sum of the loss cone loss current and neoclassical bulk viscosity current agrees the experimentally observed current in the order of magnitude at the first transition. Following second transition and an ambipolar condition in the L-mode cannot be explained by the models.
Koga, Kazuhiro*; Ohara, Norikazu*; Ino, Hiroichi*; Kondo, Katsumi*; Ito, Hideaki; Ashida, Takashi; Nakamura, Toshiyuki
FAPIG, (190), p.3 - 8, 2015/07
no abstracts in English
Kobayashi, Tatsuya*; Ito, Kimitaka*; Ido, Takeshi*; Kamiya, Kensaku; Ito, Sanae*; Miura, Yukitoshi; Nagashima, Yoshihiko*; Fujisawa, Akihide*; Inagaki, Shigeru*; Ida, Katsumi*; et al.
Nuclear Fusion, 54(7), p.073017_1 - 073017_14, 2014/07
Times Cited Count：26 Percentile：77.22(Physics, Fluids & Plasmas)In the JFT-2M tokamak, limit-cycle oscillation among several variables is observed before L-to-H transition. Spatiotemporal dynamics of the LCO is analyzed in detail. Zonal fows are not seen, and modulation in edge-localized poloidal flow and density gradient is observed. Modulation is also seen in Reynolds stress, caused by that in turbulence intensity and turbulence wavenumber. However, flow acceleration is not able to be explained by the modulation in the Reynolds stress. Rapid inward propagation in density gradient and turbulence packet is also observed. Characteristics of the propagation are veried by means of turbulence spreading theory and diffusion theory.
Kamiya, Kensaku; Matsunaga, Go; Honda, Mitsuru; Miyato, Naoaki; Urano, Hajime; Kamada, Yutaka; Ida, Katsumi*; Ito, Kimitaka*; JT-60 Team
Contributions to Plasma Physics, 54(4-6), p.591 - 598, 2014/06
Times Cited Count：6 Percentile：29.76(Physics, Fluids & Plasmas)no abstracts in English
Iguchi, Masahide; Saito, Toru; Kawano, Katsumi; Chida, Yutaka; Nakajima, Hideo; Ogawa, Tsuyoshi*; Katayama, Yoshinori*; Ogata, Hiroshige*; Minemura, Toshiyuki*; Tokai, Daisuke*; et al.
Fusion Engineering and Design, 88(9-10), p.2520 - 2524, 2013/10
Times Cited Count：10 Percentile：61.16(Nuclear Science & Technology)ITER TFC structures are large welding structures made of heavy thick stainless steels. JAEA plans to apply narrow gap TIG welding with FMYJJ1 which is full austenitic stainless filler material to manufacture TFC structure. FMYJJ1 is specified in "Codes for Fusion Facilities -Rules on Superconducting Magnet Structure (2008)". In order to evaluate effect of base material combinations and thickness of welded joint on tensile properties at 4 K, tensile tests were conducted at 4 K by using tensile specimens taken from 40 mm thickness weld joints of four combinations and 200 mm thickness ones of two combinations of base materials. These weld joints were manufactured by one side narrow gap TIG welding with FMYJJ1. As the results, it was confirmed that yield and tensile strengths of welded joint at 4K were decreased with decreasing of nitrogen of base material, and there were no large distribution of strengths at 4 K along the thickness of welded joints of 200 mm thickness.
Kobayashi, Tatsuya*; Ito, Kimitaka*; Ido, Takeshi*; Kamiya, Kensaku; Ito, Sanae*; Miura, Yukitoshi; Nagashima, Yoshihiko*; Fujisawa, Akihide*; Inagaki, Shigeru*; Ida, Katsumi*; et al.
Physical Review Letters, 111(3), p.035002_1 - 035002_5, 2013/07
Times Cited Count：94 Percentile：94.33(Physics, Multidisciplinary)In this Letter, we report analyses of spatiotemporal dynamics of turbulence and structure in the limit cycle oscillation that precedes L-to-H transition. Zonal flows are not observed during LCO, and the oscillation is the periodic generations/decays of barrier with edge localized mean flow. Oscillatory Reynolds stress is found too small to accelerate the LCO flow. Changes of the density gradient and turbulence amplitude are found to propagate into the core in a ballistic manner, suggesting a cause of fast change of core transport after H-mode transition.
Ida, Katsumi; Kamiya, Kensaku; Suzuki, Yasuhiro*
Purazuma, Kaku Yugo Gakkai-Shi, 89(5), p.319 - 327, 2013/05
This paper provides and proposes a new technique to determine the location of the LCFS that is based on a characterization of the Er structure derived from CXS measurements in the LHD. We found that the spatial derivative in the Er structure had the local maximum value at the region very near, or possibly outside the vacuum LCFS location of vacuum magnetic field at the outer midplane in the low beta plasma.
Kamiya, Kensaku; Ida, Katsumi*; Yoshinuma, Mikiro*; Suzuki, Chihiro*; Suzuki, Yasuhiro*; Yokoyama, Masayuki*; LHD Experimental Group*
Nuclear Fusion, 53(1), p.013003_1 - 013003_9, 2013/01
Times Cited Count：17 Percentile：60.01(Physics, Fluids & Plasmas)This paper provides and proposes a new technique to determine the location of the LCFS that is based on a characterization of the 
structure derived from CXS measurements in the LHD. We found that the spatial derivative in the structure had the local maximum value at the region very near, or possibly outside the vacuum LCFS location of vacuum magnetic field at the outer midplane in the low 
plasma.
Kamiya, Kensaku; Honda, Mitsuru; Miyato, Naoaki; Urano, Hajime; Yoshida, Maiko; Sakamoto, Yoshiteru; Matsunaga, Go; Oyama, Naoyuki; Koide, Yoshihiko; Kamada, Yutaka; et al.
Nuclear Fusion, 52(11), p.114010_1 - 114010_12, 2012/10
Times Cited Count：10 Percentile：40.83(Physics, Fluids & Plasmas)Depending on the direction of the external tangential momentum input, substantial changes in not only toroidal but also poloidal flows for the carbon impurity ions are observed at around the -well region. The shear in the edge becomes wider in the co-NBI case, while the edge -well becomes deeper in the counter-NBI case.
Ida, Katsumi*; Kamiya, Kensaku; Isayama, Akihiko; Sakamoto, Yoshiteru; JT-60 Team
Physical Review Letters, 109(6), p.065001_1 - 065001_4, 2012/08
Times Cited Count：43 Percentile：84.34(Physics, Multidisciplinary)The transport inside the magnetic island is investigated in the plasma during the transient phase after the back transition from 
-mode to 
-mode, where a sudden drop of temperature outside the magnetic island causes a peaking of ion temperature at the 
-point inside the magnetic island.
Iguchi, Masahide; Saito, Toru; Kawano, Katsumi; Takano, Katsutoshi; Tsutsumi, Fumiaki; Chida, Yutaka; Nakajima, Hideo
AIP Conference Proceedings 1435, p.70 - 77, 2012/06
Times Cited Count：2 Percentile：63.67(Physics, Applied)A prediction method for tensile strengths at liquid helium temperature (4K) has been developed in order to rationalize qualification tests of cryogenic structural materials used in large superconducting magnet for a fusion device. This method is to use quadratic curves which are expressed as a function of carbon and nitrogen contents and strengths at room temperature. This study shows results of tensile tests at 4K and confirmation of accuracy of prediction method for tensile strengths at 4K for large forgings and thick hot rolled plates of austenitic stainless steels, which can be used in the actual coil case and radial plates of the ITER toroidal field coils. These products are 316LN having high nitrogen from 0.09 to 0.24% and maximum thickness is 600mm. As the results, it was confirmed that the tensile strengths of these products at 4K can be predicted by using appropriate quadratic curves. And distribution of strengths for each product was estimated.
Iguchi, Masahide; Chida, Yutaka; Takano, Katsutoshi; Kawano, Katsumi; Saito, Toru; Nakajima, Hideo; Koizumi, Norikiyo; Minemura, Toshiyuki*; Ogata, Hiroshige*; Ogawa, Tsuyoshi*; et al.
IEEE Transactions on Applied Superconductivity, 22(3), p.4203305_1 - 4203305_5, 2012/06
Times Cited Count：9 Percentile：47.58(Engineering, Electrical & Electronic)Japan Atomic Energy Agency (JAEA) has responsibility to procure 19 structures for ITER toroidal field (TF) coils as in-kind components. JAEA plans to use materials specified in the material section of "Codes for Fusion Facilities; Rules on Superconducting Magnet Structure (2008)" issued by the Japan Society of Mechanical Engineers (JSME) in 2008. Large forged products were produced and their mechanical properties at 4K were evaluated. In addition, the following activities have been performed; (1) to optimize the design of each weld type identified in the manufacturing sequence, (2) to qualify typical welding procedure including repair, (3) to establish welding techniques other than narrow gap TIG welding with FMYJJ1, (4) to demonstrate the manufacturing procedures through manufacture of 1-m mockups and full-scale segments of TFC structure. This paper describes the results of material qualification and industrialization activities of manufacturing processes of ITER TFC structure.
Ida, Katsumi*; Dong, J. Q.*; Kikuchi, Mitsuru; Kwon, J. M.*; Diamond, P. H.*
Nuclear Fusion, 52(2), p.027001_1 - 027001_10, 2012/02
This conference report summarizes the contributions to, and discussions at, the 1st Asia-Pacific Transport Working Group Meeting held in Toki, Japan, on 14-17 June 2011. The topics of the meeting were organized under four main headings: momentum transport, non-locality in transport, edge turbulence and L to H transition and 3D effects on transport physics. The events which initiated this meeting are also described in this report.
Yasuda, Ryo; Nitto, Koichi*; Konagai, Chikara*; Shiozawa, Masahiro*; Takenaka, Nobuyuki*; Asano, Hitoshi*; Murakawa, Hideki*; Sugimoto, Katsumi*; Nojima, Takehiro; Hayashida, Hirotoshi; et al.
Nuclear Instruments and Methods in Physics Research A, 651(1), p.268 - 272, 2011/09
Times Cited Count：7 Percentile：48.91(Instruments & Instrumentation)Neutron radiography is one of useful tools to visualize water behavior in fuel cells under operation. In order to observe the detailed information about the water distribution in MEA and GDL in fuel cells, a high spatial resolution and high sensitivity neutron imaging system are required. We developed an imaging system using the neutron color imaging intensifier and continuously observed water distribution in operating a fuel cell. By using the system, a small type fuel cell under operation was continuously observed at the TNRF in every 20 sec. In the results, the water area was appeared from GDL and MEA, and expanded to the channel of the cathode side. On the other hand, voltage was gradually reduced with the operation time, and steeply dropped. It is considered that voltage drop was caused by blockage of gas flow due to the piling up water in the channel of the cathode side.
Usuki, Toshiyuki; Yoshida, Katsumi*; Yano, Toyohiko*; Miwa, Shuhei; Osaka, Masahiko
Progress in Nuclear Energy, 53(7), p.1078 - 1081, 2011/09
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)The effects of sintering additives of magnesium silicates, i.e. enstatite (MgSiO
), steatite (MgSiO) and forsterite (MgSiO
), on the fabrication properties and characteristics of the silicon nitride ceramics based inert matrix fuels were experimentally investigated. CeO was selected as simulating element of AmO. Sintered pellets were characterized in term of their densities, thermal conductivities and solubility to nitric acid. The densifications of sintered bodies were enhanced by using additives of magnesium silicates at relative low sintering temperature. The relative density of silicon nitride ceramics based inert matrix fuels with forsterite were achieved above 90% at 1723 K. The thermal conductivities of silicon nitride ceramics based inert matrix fuels varied according to sintering temperature, and those sintered at 1923 K were above 34 W/m K. The grain boundary phases in Silicon nitride ceramics based inert matrix fuels found to be dissolved into HNO.
