Kajimoto, Ryoichi; Ishikado, Motoyuki*; Kira, Hiroshi*; Kaneko, Koji; Nakamura, Mitsutaka; Kamazawa, Kazuya*; Inamura, Yasuhiro; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Murai, Naoki; et al.
Physica B; Condensed Matter, 556, p.26 - 30, 2019/03
Iwasawa, Yuzuru*; Abe, Yutaka*; Kaneko, Akiko*; Kanagawa, Tetsuya*; Saito, Shimpei*; Matsuo, Eiji*; Ebihara, Kenichi; Sakaba, Hiroshi*; Koyama, Kazuya*; Nariai, Hideki*
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05
For the safety design in which heat is properly removed from the molten fuel after the core disruptive accident in a sodium-cooled fast reactor, the estimation of the breakup behavior of molten fuel discharged into the coolant like a jet is desired. In order to investigate the influence of viscocity on the jet behavior, we simulated a jet discharged into a coolant using the three-dimensional lattice Boltzmann model for two-phase fluid, and examined the influence of Ohnesorge number and Reynolds number on the jet behavior. As a result, we made clear that it is necessary to consider viscosity of the coolant as well as that of the jet for the estimation of jet behavior.
Kobayashi, Riki*; Kaneko, Koji; Saito, Kotaro*; Mignot, J.-M.*; Andr, G.*; Robert, J.*; Wakimoto, Shuichi; Matsuda, Masaaki*; Chi, S.*; Haga, Yoshinori; et al.
Journal of the Physical Society of Japan, 83(10), p.104707_1 - 104707_5, 2014/10
Matsuo, Eiji*; Abe, Yutaka*; Iwasawa, Yuzuru*; Ebihara, Kenichi; Kaneko, Akiko*; Sakaba, Hiroshi*; Koyama, Kazuya*
Dai-18-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu, p.75 - 76, 2013/06
When supposing a core distractive accident (CDA) in a sodium-cooled fast reactor (SFR), it is necessary to understand the breakup behavior of the molten core material jet into coolant. Thus, the jet breakup was simulated by the lattice Boltzmann (LB) HCZ model. First, the applicability to jet breakup of the LBHCZ model was verified by comparing the simulation result to our experimental data. Next, from sensitive analyses by the simulation, it was found that the jet breakup length is in good agreement with Epstein's correlation when hydrodynamic fragmentation is a dominant phenomenon of the jet breakup.
Iwasawa, Yuzuru*; Abe, Yutaka*; Matsuo, Eiji*; Ebihara, Kenichi; Kaneko, Akiko*; Sakaba, Hiroshi*; Koyama, Kazuya*
Dai-18-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu, p.77 - 78, 2013/06
When supposing a core distractive accident (CDA) in a sodium-cooled fast reactor (SFR), it is necessary to understand the breakup behavior of the molten core material jet into coolant. In order to examine the effect of ambient fluid around the jet, the surface and fragmentation behavior was investigated using the lattice Boltzmann (LB) HCZ model. As a result, it was confirmed that the mechanism of the jet breakup behavior is one proposed by Epstein when hydrodynamic fragmentation is the dominant phenomenon for the jet break up.
Iwasawa, Yuzuru*; Abe, Yutaka*; Kaneko, Akiko*; Kuroda, Taihei*; Matsuo, Eiji*; Ebihara, Kenichi; Sakaba, Hiroshi*; Koyama, Kazuya*; Ito, Kazuhiro*; Nariai, Hideki*
Proceedings of 15th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-15) (USB Flash Drive), 12 Pages, 2013/05
In the safety design of a Fast Breeder Reactor(FBR), when it is supposed that a Core Disruptive Accident(CDA) occurs, it is strongly required that molten core materials are completely solidified and are cooled down by sodium coolant in a reactor vessel. In this study, we injected molten alloy and transparent fluid, which are a simulant of the molten core material, into water, which is a simulant of the coolant. In this study, we injected molten alloy and transparent fluid, which simulate the molten core material, into water, which simulates the coolant. In the experiment, we observed the jet breakup behavior of them using a high speed video camera, and compared the observe images with the previous theories. In addition, we simulated numerically the qualitative behavior of the liquid jet using a two-phase fluid model of the lattice Boltzmann method.
Masuda, Takatsugu*; Kitaoka, Shuji*; Takamizawa, Satoshi*; Metoki, Naoto; Kaneko, Koji; Rule, K. C.*; Kiefer, K.*; Manaka, Hiroshi*; Nojiri, Hiroyuki*
Physical Review B, 81(10), p.100402_1 - 100402_4, 2010/00
Spin dynamics of the square lattice Heisenberg antiferromagnet, BaMnGeO, is studied by a combination of bulk measurements, neutron diffraction, and inelastic neutron-scattering techniques. Easy plane type antiferromagnetic order is identified at T4.0 K. The exchange interactions are estimated as = 27.8(3) eV and = 1.0(1) eV, and the saturation field is 9.75 T. Magnetic excitation measurements with high experimental resolution setup by triple axis neutron spectrometer reveals the instability of one magnon excitation in the field range of 0.7 0.85.
Seito, Hajime; Ichikawa, Tatsuya*; Hanaya, Hiroaki; Sato, Yoshishige*; Kaneko, Hirohisa; Haruyama, Yasuyuki; Watanabe, Hiroshi*; Kojima, Takuji
Radiation Physics and Chemistry, 78(11), p.961 - 965, 2009/11
no abstracts in English
Seito, Hajime; Ichikawa, Tatsuya*; Kaneko, Hirohisa; Sato, Yoshishige*; Watanabe, Hiroshi*; Kojima, Takuji
Radiation Physics and Chemistry, 78(5), p.356 - 359, 2009/05
Iwamoto, Yosuke; Sakamoto, Yukio; Matsuda, Norihiro; Nakane, Yoshihiro; Ochiai, Kentaro; Kaneko, Hirohisa; Niita, Koji*; Shibata, Tokushi; Nakashima, Hiroshi
Nuclear Instruments and Methods in Physics Research A, 598(3), p.687 - 695, 2009/01
Double-differential neutron-production cross-sections of a thin beryllium target bombarded with 10 MeV protons and deuterons were measured. Neutron energy spectra in the range above 1.8 MeV were obtained by a time-of-flight method at angles of 15, 30, 45, 60, 75, 90 and 120 degrees. Monte Carlo calculations with the PHITS code were performed using the evaluated nuclear data files ENDF/B-VII, the Bertini/GEM model and the JQMD/GEM model, and compared with the experimental results. It was found that the calculated results using ENDF/B-VII and Bertini/GEM for the Be(p,xn) reaction and JQMD/GEM for the Be(d,xn) reaction roughly agreed with the experimental results.
Seito, Hajime; Ichikawa, Tatsuya*; Haneda, Noriyuki; Kaneko, Hirohisa; Sato, Yoshishige*; Watanabe, Hiroshi*; Kojima, Takuji
JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 200, 2008/03
no abstracts in English
Shibano, Junichi*; Shobu, Takahisa; Suzuki, Kenji*; Kiriyama, Koji; Kajiwara, Kentaro*; Kaneko, Hiroshi; Kobayashi, Michiaki*
Materials Science Forum, 571-572, p.267 - 270, 2008/00
Hattori, Takanori; Saito, Hiroyuki; Kaneko, Hiroshi; Okajima, Yuka; Aoki, Katsutoshi; Utsumi, Wataru
KEK Proceedings 2007-7, p.56 - 60, 2007/12
We introduce high-pressure study on amorphous materials using a multi-anvils press equipped with the X-ray transparent cBN anvils. First, we mention merits of the angle-dispersive X-ray diffraction system compared with the conventional energy-dispersive system. Next, we show the results of the verification of the high-pressure formation of the elemental bulk metallic glass as an example. Finally, the characteristics of X-ray absorption are shown both for the combinational sintered diamond anvils and the presently used cBN anvils.
Yokoyama, Sumi; Sato, Kaoru; Manabe, Kentaro; Noguchi, Hiroshi; Kaneko, Hirohisa; Oki, Yuichi*; Iida, Takao*; Tanaka, Susumu*
Radiation Protection Dosimetry, 127(1-4), p.392 - 397, 2007/11
To estimate internal doses due to the inhalation of radionuclides produced by the nuclear spallation of the air nuclei in high-energy proton accelerator facilities, the physicochemical properties of radionuclides are very important. However, there is not enough information of the properties for airborne radioactive chlorine formed from argon gas in the air of a high-energy proton irradiation field. Thus we have measured the ratio of aerosol and gases of radioactive chlorine which are formed by irradiating argon gas-added air with a 48 MeV proton beam. In addition, the particle size distribution and chemical form of non-radioactive aerosol were examined. It was found that Cl-38 and Cl-39 exist as aerosol, acidic and non-acidic gases. The percentages of Cl-38 and Cl-39 aerosols are more than 70%. In total radioactive chlorine gas, about 30% and 70% are acidic and non-acidic gases, respectively. The concentration of non-radioactive aerosol had a peak at an aerodynamic diameter of 20-30 nm in the early irradiation period. The particle size of non-radioactive aerosol shifted to larger with time. After 10 min, the aerosols grew very slowly and many of the non-radioactive aerosols were distributed widely under 200 nm. This suggests that the diameter of the radioactive chlorine aerosol formed by the attachment of the radioactive chlorine to the non-radioactive aerosol around a beam line of the accelerator is much smaller than the default value adopted in ICRP Publication 66.
Motojima, Osamu*; Yamada, Hiroshi*; Komori, Akio*; Oyabu, Nobuyoshi*; Muto, Takashi*; Kaneko, Osamu*; Kawahata, Kazuo*; Mito, Toshiyuki*; Ida, Katsumi*; Imagawa, Shinsaku*; et al.
Nuclear Fusion, 47(10), p.S668 - S676, 2007/10
The performance of net-current free heliotron plasmas has been developed by findings of innovative operational scenarios in conjunction with an upgrade of the heating power and the pumping/fuelling capability in the Large Helical Device (LHD). Consequently, the operational regime has been extended, in particular, with regard to high density, long pulse length and high beta. Diversified studies in LHD have elucidated the advantages of net-current free heliotron plasmas. In particular, an internal diffusion barrier (IDB) by a combination of efficient pumping of the local island divertor function and core fuelling by pellet injection has realized a super dense core as high as 510 m, which stimulates an attractive super dense core reactor. Achievements of a volume averaged beta of 4.5% and a discharge duration of 54 min with a total input energy of 1.6 GJ (490 kW on average) are also highlighted. The progress of LHD experiments in these two years is overviewed by highlighting IDB, high-beta and long pulse.
Shibano, Junichi*; Shobu, Takahisa; Suzuki, Kenji*; Hirata, Tomoyuki*; Kaneko, Hiroshi; Kobayashi, Michiaki*
Zairyo, 56(10), p.985 - 992, 2007/10
This paper presents a basic research on a measurement of strain in the bulk of materials by using high energy white X-rays from a synchrotron radiation source of SPring-8. WEL-TEN780E (JIS G3128 SHY685) whose grain size was 0.013 mm was used as a specimen. The specimen was loaded with four point bending. The white X-ray beam, which has a height of 0.05 mm and width of 0.03 mm, was incident in it. Bending strain at the surface of specimen was measured by a strain gauge. The internal strain of SHY685 of 5 mm thickness could be evaluated using white X-rays which range of energy from 60 keV to 150 keV. Furthermore, the measurement error of strain could be decreased by using the diffracted X-rays with high energy, high peak count and the profile which is close to Gaussian curve. The results showed that the high energy white X-ray is effective for internal strain measurements.
Hattori, Takanori; Saito, Hiroyuki; Aoki, Katsutoshi; Kaneko, Hiroshi; Okajima, Yuka; Utsumi, Wataru
Nihon Kessho Gakkai-Shi, 49(3), p.179 - 185, 2007/06
The high-pressure formation of the bulk metallic glass of elemental Zr and Ti, which has been recently reported, is verified by a newly developed angle dispersive X-ray diffraction (ADX) system using a large volume multi-anvil apparatus equipped with X-ray transparent anvils. The ADX data revealed that Zr and Ti remain as a crystalline form at high-pressure and temperature condition where the amorphization has been reported. The misinterpretation in the previous papers is attributed to the anomalous rapid grain growth that is related to the characteristic lattice dynamic and the resulting anomalously fast self diffusion in the high-temperature phases of Zr and Ti.
Watanuki, Tetsu; Machida, Akihiko; Ikeda, Tomohiro*; Omura, Ayako*; Kaneko, Hiroshi; Aoki, Katsutoshi; Sato, Taku*; Tsai, A. P.*
Philosophical Magazine, 87(18-21), p.2905 - 2911, 2007/06
We have constructed a single-crystal synchrotron X-ray diffraction system to precisely study the structure under hydrostatic pressure conditions at low temperatures and applied it to a study on the phase transition phenomena of a Cd-Yb periodic approximant and a Cd-Yb quasicrystal. Four phases were newly observed for the 1/1 approximant crystal in a span up to 5.2 GPa and down to 10 K. The innermost part of the atomic clusters of Cd tetrahedra exhibited various orientational ordering sensitively depending on pressure and temperature. High pressure diffraction measurements using a highly parallel synchrotron X-ray beam and a hydrostatically compressed single crystal enabled us to detect the weak diffractions due to the subtle structural changes.
Saito, Hiroyuki; Utsumi, Wataru; Kaneko, Hiroshi; Aoki, Katsutoshi
Journal of Crystal Growth, 300(1), p.26 - 31, 2007/03
We have performed the synthesis study of group-III nitride crystals using a cubic-anvil-type large volume high pressure apparatus. Bulk crystals of the nitride compounds, which are key materials for developing optoelectronic and high-power/ frequency devices, can hardly be prepared by the conventional crystal growth technique such as the Bridgman method since they decompose on heating at ambient pressure before reaching the melting points. Appling pressure is expected to suppress decomposition reaction and consequently allow crystal growth from their melts. I will talk about the crystal growth of GaN and AlGaN under high pressure, and phase stability of InN under high pressure and temperature.
Motojima, Osamu*; Yamada, Hiroshi*; Komori, Akio*; Oyabu, Nobuyoshi*; Kaneko, Osamu*; Kawahata, Kazuo*; Mito, Toshiyuki*; Muto, Takashi*; Ida, Katsumi*; Imagawa, Shinsaku*; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 12 Pages, 2007/03
The performance of net-current free Heliotron plasmas has been developed by findings of innovative operational scenarios in conjunction with an upgrade of the heating power and the pumping/fueling capability in the Large Helical Device (LHD). Consequently, the operational regime has been extended, in particular, with regard to high density, long pulse length and high beta. Diversified studies in LHD have elucidated the advantages of net-current free heliotron plasmas. In particular, an Internal Diffusion Barrier (IDB) by combination of efficient pumping of the local island divertor function and core fueling by pellet injection has realized a super dense core as high as 510m, which stimulates an attractive super dense core reactor. Achievements of a volume averaged beta of 4.5 % and a discharge duration of 54-min. with a total input energy of 1.6 GJ (490 kW in average) are also highlighted. The progress of LHD experiments in these two years is overviewed with highlighting IDB, high and long pulse.