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Gu, B.; Sugai, Isamu*; Ziman, T.*; Guo, G. Y.*; Nagaosa, Naoto; Seki, Takeshi*; Takanashi, Koki; Maekawa, Sadamichi
Physical Review Letters, 105(21), p.216401_1 - 216401_4, 2010/11
Times Cited Count：71 Percentile：89.89(Physics, Multidisciplinary)Aso, Tomokazu; Tatsumoto, Hideki; Hasegawa, Shoichi; Otsu, Kiichi; Uehara, Toshiaki; Kawakami, Yoshihiko; Sakurayama, Hisashi; Maekawa, Fujio; Futakawa, Masatoshi; Ushijima, Isamu*
Proceedings of International Cryogenic Engineering Conference 22 (ICEC-22) and International Cryogenic Materials Conference 20 (ICMC 2008), p.741 - 746, 2009/00
no abstracts in English
Nishimura, Motohiko*; Nonaka, Yoshiharu*; Maekawa, Isamu*
JNC TJ9400 2005-002, 55 Pages, 2005/07
JNC-TJ9400-2005-002.pdf:74.29MB
Sodium cooled FBR reactor in a feasibility study on commercialized fast reactor system has been designed so compact that flow velocity is much higher in the reactor than in the reactors so far. This design requires an evaluation method for gas entrainment from reactor free surface and effective countermeasures. Focusing on the establishment of gas entrainment evaluation method based on CFD, CFD simulation has been carried out with analyses of an existing gas entrainment experiment. In the analyses, four turbulence models such as standard k-e, RNG k-e, non-linear k-e and k-w have been applied and evaluated for their analytical capability in addition to laminar model. Main results have been obtained as follows;1) Laminar model shows faster vortices behavior accompanied with strong flow and pressure fluctuations including random variations than any other turbulence models. RNG model shows the solutions more similar to the laminar model than the other turbulence models.2) k-w, non-linear k-e and Standard k-e models show milder vortices behavior in this order due to excess turbulence viscosity.3) Main characteristics of major turbulence models have been obtained when they are applied to gas entrainment analysis.
Katanishi, Shoji; Kunitomi, Kazuhiko; Tsuji, Nobumasa*; Maekawa, Isamu*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(3), p.257 - 267, 2004/09
no abstracts in English
Kurata, Chikatoshi*; Maekawa, Isamu*
JNC TJ4400 2004-001, 133 Pages, 2004/02
JNC-TJ4400-2004-001.pdf:10.91MB
none
Ninokata, Hisashi*; Misawa, Takeharu*; Baglietto, E.*; Aoki, Takayuki*; Sorokin, A. P.*; Maekawa, Isamu*; Ohshima, Hiroyuki; Yamaguchi, Akira
JNC TY9400 2003-010, 170 Pages, 2003/03
JNC-TY9400-2003-010.pdf:5.42MB
A method of large scale direct numerical simulation of turbulent flows in a high burn-up fuel pin bundle is proposed to evaluate wall shear stress and temperature distributions on the pin surfaces as well as detailed coolant velocity and temperature distributions inside subchannels under various thermal hydraulic conditions. This simulation is aimed at providing a tool to confirm margins to thermal hydraulics design limits of the nuclear fuels and at the same time to be used in design-by-analysis approaches. The method will facilitate thermal hydraulic design of high performance LMFR core fuels characterized by high burn-up, ultra long life, high reliable and safe performances, easiness of operation and maintenance, minimization of radio active wastes, without much relying on such empirical approach as hot spot factor and sub-factors, and above all the high cost mock up experiments. A pseudo direct numerical simulation of turbulence (DNS) code is developed, first on the Cartesian coordinates and then on the curvilinear boundary fit coordinates that enables us to reproduce thermal hydraulics phenomena in such a complicated flow channel as subchannels in a nuclear fuel pin assembly. The coordinate transformation is evaluated and demonstrated to yield correct physical quantities by carrying out computations and comparisons with experimental data with respect to the distributions of various physical quantities and turbulence statistics for fluid flow and heat transfers in various kinds of simple flow channel geometry. Then the boundary fitted pseudo DNS for flows inside an infinite pin array configuration is carried out and compared with available detailed experimental data. In parallel similar calculations are carried out using a commercial code STAR-CD to cross-check the DNS performances. As a result, the pseudo DNS showed reasonable comparisons with experiments as well as the STAR-CD results. Importance of the secondary flow influences is emphasized on the momentum a
Takata, Takashi; Yamaguchi, Akira; Maekawa, Isamu*
Nuclear Engineering and Design, 220(1), p.37 - 50, 2002/00
Times Cited Count：27 Percentile：83.93(Nuclear Science & Technology)None
Mori, Yuichiro*; Maekawa, Isamu*; Shimoda, Sadayuki*; Sato, Hiroyuki; Nomoto, Yasunobu; Ohashi, Hirofumi; Tachibana, Yukio
no journal, ,
no abstracts in English
Kasuga, Shoji*; Kubota, Kenichi*; Okamoto, Futoshi*; Maekawa, Isamu*; Furihata, Noboru*; Saito, Masanao*; Kido, Yuji*; Ohashi, Hirofumi; Tachibana, Yukio; Kunitomi, Kazuhiko
no journal, ,
Conceptual design of a small-sized HTGR for electricity generation and district heating has been conducted by JAEA with support of Japanese vendors: Toshiba Corporation, Fuji Electric, Kawasaki Heavy Industries, Nuclear Fuel Industries, Shimizu Corporation, and Marubeni Utility Services. System design as well as nuclear design of the first core of HTR50S using the same CFPs as the HTTR has been performed and the nuclear design shows upgraded performance of the reactor compared with the HTTR.
