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Uchibori, Akihiro; Watanabe, Akira*; Takata, Takashi; Ohshima, Hiroyuki
Nuclear Technology, 205(1-2), p.119 - 127, 2019/01
Times Cited Count：3 Percentile：31.89(Nuclear Science & Technology)To evaluate a sodium-water reaction phenomenon in a steam generator of sodium-cooled fast reactors, a computational fluid dynamics code SERAPHIM, in which a compressible multicomponent multiphase flow with sodium-water chemical reaction is computed, has been developed. The original SERAPHIM code is based on the difference method. In this study, unstructured mesh-based numerical method was developed to advance a numerical accuracy for the complex-shaped domain including multiple heat transfer tubes. Numerical analysis of an underexpanded jet experiment was performed as part of validation of the unstructured mesh-based numerical method. The calculated pressure profile and location of the Mach disk showed good agreement with the experimental data. Applicability of the numerical method for the actual situation was confirmed through the analysis of water vapor discharging into liquid sodium.
Uchibori, Akihiro; Watanabe, Akira*; Takata, Takashi; Ohshima, Hiroyuki
Journal of Nuclear Science and Technology, 54(10), p.1036 - 1045, 2017/10
Times Cited Count：5 Percentile：44.54(Nuclear Science & Technology)To evaluate a sodium-water reaction phenomenon in a steam generator of sodium-cooled fast reactors, a computational fluid dynamics code SERAPHIM, in which a compressible multicomponent multiphase flow with sodium-water chemical reaction is computed, has been developed. The original SERAPHIM code is based on the difference method. In this study, unstructured mesh-based numerical method was developed to advance a numerical accuracy for the complex-shaped domain including multiple heat transfer tubes. Numerical analysis of an underexpanded jet experiment was performed as part of validation of the unstructured mesh-based numerical method. The calculated pressure profile showed good agreement with the experimental data. Applicability of the numerical method for the actual situation was confirmed through the analysis of water vapor discharging into liquid sodium. The effect of use of the unstructured mesh was also investigated by the two analyses using structured and unstructured mesh.
Uchibori, Akihiro; Takata, Takashi; Ohshima, Hiroyuki; Watanabe, Akira*
Proceedings of 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17) (USB Flash Drive), 12 Pages, 2017/09
To evaluate a sodium-water reaction phenomenon in a steam generator of sodium-cooled fast reactors, a computational fluid dynamics code SERAPHIM, in which a compressible multicomponent multiphase flow with sodium-water chemical reaction is computed, has been developed. The original SERAPHIM code is based on the difference method. In this study, unstructured mesh-based numerical method was developed to advance a numerical accuracy for the complex-shaped domain including multiple heat transfer tubes. Numerical analysis of an underexpanded jet experiment was performed as part of validation of the unstructured mesh-based numerical method. The calculated pressure profile and location of the Mach disk showed good agreement with the experimental data. Applicability of the numerical method for the actual situation was confirmed through the analysis of water vapor discharging into liquid sodium.
Esirkepov, T. Z.; Bulanov, S. S.*; Koga, J. K.; Kando, Masaki; Kondo, Kiminori; Rosanov, N. N.*; Korn, G.*; Bulanov, S. V.
Physics Letters A, 379(36), p.2044 - 2054, 2015/09
Times Cited Count：50 Percentile：89.51(Physics, Multidisciplinary)Ikeda, Takashi; Hou, Z.*; Chai, G.-L.*; Terakura, Kiyoyuki*
Hyomen Kagaku, 36(7), p.345 - 350, 2015/07
Carbon alloy catalysts (CACs) are one of promising candidates for platinum-substitute cathode catalysts for polymer electrolyte fuel cells. We have investigated possible mechanisms of oxygen reduction reactions (ORRs) for CACs via first-principles-based molecular dynamics simulations. In this contribution, we review possible ORRs at likely catalytic sites of CACs suggested from our simulations.
Ikeda, Takashi
Koatsuryoku No Kagaku To Gijutsu, 13(3), p.224 - 231, 2003/08
Applying pressure to hydrogen-bonded crystals hydrogen bromide and hydrogen sulfide alters significantly the bonding nature and induces various kinds of phenomena: order-disorder transition, hydrogen-bond symmetrization, and molecular dissociation accompanied by the solid-state reactions. This article reviews the relationship between pressure-induced structural phase transitions and solid-state reactions, revealed from the cooperative works between high pressure experiments and the ab initio molecular dynamics simulations.
molecular beams under 1000 KTeraoka, Yuden; Yoshigoe, Akitaka; Moritani, Kosuke
Japanese Journal of Applied Physics, Part 1, 42(7B), p.4671 - 4675, 2003/07
Times Cited Count：4 Percentile：20.13(Physics, Applied)The oxidation reaction mechanisms for Si(001) by O molecules have been investigated in a surface temperature region from 860 K to 1300 K and in an incident energy region from 0.6 eV to 3.0 eV. Synchrotron Radiation photoemission spectroscopy was used for surface analysis. Si-2p photoemission spectra were measured during molecular beam irradiation so that their dependences on surface temperature and incident energy were clarified. SiO molecules, desorbed from the surface at high temperature region, were also detected by a quadrupole mass analyzer using 
O molecular beams to measure SiO desorption yield depending on surface temperature and incident energy. Consequently, a reaction scheme, oxide layers formation, etching, and coexistence of both reactions, is determined by the incident energy under 1000 K.
molecular beamsTeraoka, Yuden; Yoshigoe, Akitaka
Hyomen Kagaku, 23(9), p.553 - 561, 2002/09
no abstracts in English
) + H, D, and HD reactions on the lowest three potential energy surfacesTakayanagi, Toshiyuki
Journal of Chemical Physics, 116(6), p.2439 - 2446, 2002/02
Times Cited Count：29 Percentile：66.15(Chemistry, Physical)no abstracts in English
reaction dynamics with Si(001) surfaces as observed by synchrotron radiation photoemission spectroscopyTeraoka, Yuden; Yoshigoe, Akitaka
Atomic Collision Research in Japan, No.28, p.97 - 99, 2002/00
The translational kinetic energy of incident molecules is an important factor for the induction of surface reactions. We applied supersonic seed molecular beam techniques and high-energy-resolution photoemission spectroscopy using synchrotron radiation to the Si initial oxidation analysis. We have already found out that the saturated oxygen coverage on H
O-chemisorbed Si(001) surfaces depends on the O incident energy. Two potential energy barriers were confirmed in accordance with the first-principles calculation. An action of the incident energy should be confirmed also on clean Si(001) surfaces. Therefore, the incident energy dependence of the O dissociative chemisorption on the clean Si(001) surface has been investigated by photoemission spectroscopy for Si-2p and O-1s core levels to make clear how the incident energy affects the ultra-thin oxide-layers formation.
analysis using high resolution synchrotron radiation photoemission spectroscopy for initial oxidation of HO pre-adsorbed Si(001) surfaces induced by supersonic O molecular beams at room temperatureYoshigoe, Akitaka; Teraoka, Yuden
Atomic Collision Research in Japan, No.28, p.105 - 107, 2002/00
The oxidation states up to Si
states were formed when the translational kinetic energy of O was 3.0 eV. The time evolustions of each Si oxidation states were in situ measured by using the high resolution photoemission spectroscopy.The translational kinetic energy of 3.0eV randomly enhanced the oxidation on Si(001) surface up to the second layer Si backbonds. It was found that the Si was not observed, thus the dimer Si atoms at the top layer was not surrounded by four oxygen atoms at the initial oxidation stage.
molecular beamsTeraoka, Yuden; Yoshigoe, Akitaka
SPring-8 Research Frontiers 2000/2001, p.48 - 50, 2001/00
no abstracts in English
in the ground electronic stateYokoyama, Keiichi; ;
Journal of Chemical Physics, 102(20), p.7902 - 7909, 1995/05
Times Cited Count：18 Percentile：56.45(Chemistry, Physical)no abstracts in English
Ugajin, Mitsuhiro; Shiba, Koreyuki
Journal of Nuclear Materials, 105(2), p.211 - 218, 1982/00
Times Cited Count：12 Percentile：75.26(Materials Science, Multidisciplinary)no abstracts in English
Serizawa, Hiroyuki; Osawa, Takahito; Oishi, Yuji*; Nemoto, Yoshiyuki; Kondo, Keietsu; Shohoji, Nobumitsu*; Kaji, Yoshiyuki
no journal, ,
A new reaction model for evaluating the activity of oxygen and hydrogen atoms of HO molecules is proposed. The surprisingly high value of the activity implies that the production process of volatile metal hydroxides might be reconsidered.
Sato, Takumi; Yamashita, Takuya; Shimomura, Kenta; Nagae, Yuji
no journal, ,
