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Yanagisawa, Tsutomu*; Usami, Shin; Maeda, Seiichiro
Genshiryoku Nenkan 2018, p.90 - 95, 2017/10
no abstracts in English
Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10
no abstracts in English
Moriyama, Kiyofumi; Maruyama, Yu; Usami, Tsutomu*; Nakamura, Hideo
JAERI-Research 2005-017, 173 Pages, 2005/08
JAERI-Research-2005-017.pdf:11.17MB
A series of experiments on the break-up of high temperature oxide and steel melt jets in a water pool was conducted. The objective was to obtain data for the jet break-up length and size distribution of the droplets produced by the jet break-up, and information on the influence of material properties. Also, we tried to obtain additional information giving a clue to the mechanism governing the melt jet break-up, such as flow intensity of the steam column surrounding the melt jet, and its relation with the droplet size. In the experiments, zirconia-alumina mixture and stainless steel melt jets with diameter 
17mm and velocity 7.8m/s at the water surface were dropped into a deep (2.1m) or shallow (0.6m) water pool with various subcool. From the results of the present experiments and also by referring other experimental data from literature, we obtained empirical correlation equations for the jet break-up length, the fraction of jet broken-up in a shallow pool where the jet was not completely broken-up, and the droplet size.
Usami, Tsutomu; Moriyama, Kiyofumi; Nishikizawa, Tomotoshi; Nakamura, Hideo
JAERI-Tech 2005-028, 37 Pages, 2005/05
JAERI-Tech-2005-028.pdf:16.32MB
The steam explosion during a severe accident in a light water reactor, which may occur by the contact of molten core and coolant, has been known as a potential threat on the integrity of the containment vessel, and has been studied in the nuclear safety research field. Prediction of the intensity of steam explosions needs an understanding of the initial premixture. However, visual observation of the premixture in experiments is usually difficult due to the vapor generation. Thus, we investigated the possibility of a high-speed X-ray visualization with a 4500 f/s high speed video camera with an image-intensifier and three kinds of scintillator materials: CdWO
, ZnS(Ag) and CsI(Tl). A modeled premixture consisted of metal objects and bubbles in a water vessel was used. The test result showed that the CsI(Tl) scintillator gave the best image quality among the three and the high-speed visualization at 4500 f/s was possible, though in the still picture which carried out one of the recorded picture, the picture became indistinct.
Nishimura, Akihiko; Sugiyama, Akira; Usami, Tsutomu; Ohara, K.*
Journal of Materials Science; Materials in Electronics, 14(1), p.1 - 3, 2003/01
no abstracts in English
Nishimura, Akihiko; Akaoka, Katsuaki; Ozu, Akira; Usami, Tsutomu*
Journal of Nuclear Science and Technology, 38(12), p.1043 - 1047, 2001/12
no abstracts in English
Nishimura, Akihiko; Usami, Tsutomu*; Deki, Kyoichi*; Shimobeppu, Y.*; Hayasaka, N.*; Arisawa, Takashi
Technical Digest on 4th Pacific Rim Conference on Lasers and Electro-Optics (CLEO/Pacific Rim 2001), p.II_280 - II_281, 2001/00
no abstracts in English
Ozu, Akira; Nishimura, Akihiko; Usami, Tsutomu*; Matoba, Toru
JAERI-Research 2000-013, p.39 - 0, 2000/03
JAERI-Research-2000-013.pdf:1.8MB
no abstracts in English
Nishimura, Akihiko; Akaoka, Katsuaki; Ozu, Akira; Sugiyama, Akira; Usami, Tsutomu*; Matoba, Toru
Advanced High-power Lasers (Proceedings of SPIE Vol.3889), p.414 - 419, 2000/00
no abstracts in English
Nishimura, Akihiko; Ozu, Akira; Akaoka, Katsuaki; Usami, Tsutomu*; *; Matoba, Toru
Denki Gakkai Hikari, Ryoshi Debaisu Kenkyukai Shiryo OQD-99-1-6, p.25 - 28, 1999/03
no abstracts in English
Moriyama, Kiyofumi; Maruyama, Yu*; Usami, Tsutomu*; Nakamura, Hideo
no journal, ,
no abstracts in English
