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Uchida, Mao*; Alzahrani, H.*; Shiono, Mikihito*; Sakai, Takaaki*; Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 16 Pages, 2022/03
Gas entrainment from cover gas is one of key issues for sodium-cooled fast reactors design to prevent unexpected effects to core reactivity. A vortex model based evaluation method has been developed to evaluate the surface vortex gas core growth at the free surface in the reactor vessel. In this study, water experiments were performed to clarify the prediction accuracy for the vortex gas core growth during the vortex drift motion using a circulating water tunnel with an open flow channel test section. Gas core growth were predicted by applying the evaluation method to the numerical analyses performed in the same geometry of the experiments, and compared with the experimental results. It was observed the gas core growth became large at downstream region where downward velocity became large in experiment. However, the gas core length which were predicted from numerical result showed a discrepancy with the experimental result on the peak position and an overestimation of peak value.
Uchida, Mao*; Sakai, Takaaki*; Ezure, Toshiki; Tanaka, Masaaki
Mechanical Engineering Journal (Internet), 8(4), p.21-00161_1 - 21-00161_11, 2021/08
An evaluation method based on numerical analyses has been developed to predict occurrences gas entrainment phenomena at a free surface in a sodium-cooled fast reactor. In this study, experiments were conducted for gas entrainments due to drifting free surface vortexes observed in a circulating water tunnel geometry. Numerical analyses were also conducted in the same geometry using a computational fluid dynamics (CFD) code. Then, Strouhal numbers of vortex frequency and detailed flow velocity profiles were compared between experimental results and numerical results to clarify the evaluation accuracy of CFD calculation. As the results, the Strouhal numbers of the vortex frequency obtained from numerical analyses showed good agreement with the experimental data.
Matsushita, Kentaro; Fujisaki, Tatsuya*; Ezure, Toshiki; Tanaka, Masaaki; Uchida, Mao*; Sakai, Takaaki*
Keisan Kogaku Koenkai Rombunshu (CD-ROM), 26, 6 Pages, 2021/05
For the gas entrainment vortex at the free surface in sodium-cooled fast reactors, development of the numerical analysis method to evaluate amount of the gas entrainment from the free surface has been developing. In this paper, the automatic creation of analysis meshes which can suppress the calculation cost while maintaining the prediction accuracy of the vortex shape is investigated, and the adaptive mesh refinement (AMR) method is examined to the creation of analysis mesh applying to the unsteady vortex system. The refined mesh based on the criterion evaluated by vorticity, Q-value as second invariant of the velocity and the discriminant for the eigen equation of the velocity gradient tensor is considered, and it found that the AMR method based on Q-value can refine the analysis meshes most efficiently.
Tobari, Hiroyuki; Inoue, Takashi; Hanada, Masaya; Dairaku, Masayuki; Watanabe, Kazuhiro; Umeda, Naotaka; Taniguchi, Masaki; Kashiwagi, Mieko; Yamanaka, Haruhiko; Takemoto, Jumpei; et al.
Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03
High voltage (HV) bushing in the ITER NBI is one of critical components, which acts as a feedthrough for electric power and cooling water from the -1 MV power supply in SF
gas to beam source inside vacuum. JAEA has overcome a longstanding issue on manufacturing of a large bore ceramic ring with 1.56 m in diameter as the insulator of the five-stage HV bushing. Joining method of the ceramic and metal flange with thick Kovar plate to form vacuum boundary was also developed. By assembling components, a full-size mockup bushing simulating one stage of the HV bushing was successfully manufactured. In the voltage holding test, the high voltage of 240 kV including the margin of 20 % of a rated voltage was sustained for 3600 s without breakdown, and the voltage holding capability required in ITER was successfully verified.
Yachi, Shigeyasu; Sato, Tadashi; Suga, Shinichi*; Komuro, Yuichi; Uchida, Masaaki; Nakajima, Kunihisa; Nakamura, Jinichi; Amezawa, Hiroo; Omura, Hideaki*; Minato, Kazuo; et al.
JAERI-Review 2003-025, 162 Pages, 2003/09
JAERI-Review-2003-025.pdf:5.96MB
The report contains example of answers to the Problems of 31st(1999) to 35th(2003) Examinations for the Chief Engineer of Nuclear Fuel which were conducted as a national qualification examination. Brief explanations or references are given to some answers.
Uchida, Masaaki
JAERI-Data/Code 2002-012, 35 Pages, 2002/05
JAERI-Data-Code-2002-012.pdf:1.71MB
no abstracts in English
Uchida, Masaaki
IAEA Regional Workshop on Accident Management and Emergency Response for Research Reactors, 11 Pages, 2002/00
no abstracts in English
Takebe, Shinichi; Kimura, Hideo; Matsuzuru, Hideo; Takahashi, Tomoyuki*; Yasuda, Hiroshi*; Uchida, Shigeo*; Mahara, Yasunori*; Saeki, Akiyoshi*; Sasaki, Noriyuki*; Ashikawa, Nobuo*; et al.
JAERI-Review 2001-015, 81 Pages, 2001/05
JAERI-Review-2001-015.pdf:5.94MB
no abstracts in English
Takahashi, Tomoyuki*; Takebe, Shinichi; Kimura, Hideo; Matsuzuru, Hideo; Yasuda, Hiroshi*; Uchida, Shigeo*; Saeki, Akiyoshi*; Mahara, Yasunori*; Sasaki, Noriyuki*; Ashikawa, Nobuo*; et al.
KURRI-KR-44, p.169 - 176, 2000/02
no abstracts in English
pelletNakamura, Jinichi; Uchida, Masaaki; Uetsuka, Hiroshi; Furuta, Teruo
IAEA-TECDOC-1036, 0, p.127 - 138, 1998/08
no abstracts in English
pelletNakamura, Jinichi; Uchida, Masaaki; Uetsuka, Hiroshi; Kodaira, Tsuneo; Yamahara, Takeshi;
Proc. of Int. Topical Meeting on LWR Fuel Performance, 0, p.499 - 506, 1997/03
no abstracts in English
25th examination for the chief technician of nuclear fuelUchida, Masaaki; ; Arai, Yasuo; Minato, Kazuo; ; Takada, Kazuo; Ikawa, Katsuichi
JAERI-Review 94-001, 94 Pages, 1994/08
JAERI-Review-94-001.pdf:2.74MB
no abstracts in English
Uchida, Masaaki
Journal of Nuclear Science and Technology, 30(8), p.752 - 761, 1993/08
Times Cited Count：2 Percentile：29.79(Nuclear Science & Technology)no abstracts in English
Uchida, Masaaki; Saito, Hioraki*
JAERI-M 93-108, 36 Pages, 1993/05
no abstracts in English
Uchida, Masaaki; Nakamura, Jinichi;
JAERI-M 92-177, 39 Pages, 1992/11
no abstracts in English
Uchida, Masaaki
JAERI-M 91-132, 32 Pages, 1991/08
no abstracts in English
; *; ; Nakamura, Jinichi; Uchida, Masaaki
JAERI-M 91-003, 38 Pages, 1991/02
no abstracts in English
Uetsuka, Hiroshi; Nakamura, Jinichi; Nagase, Fumihisa; Uchida, Masaaki; Furuta, Teruo
Fuel Performance Experiment and Analysis and Computerised Man-Machine Communication, p.1 - 11, 1990/09
no abstracts in English
Uchida, Masaaki; Saito, Hioraki*
JAERI-M 90-002, 30 Pages, 1990/02
no abstracts in English
Muramatsu, Ken; ; Uchida, Masaaki; Soda, Kunihisa
JAERI-M 88-261, 54 Pages, 1989/01
no abstracts in English
