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Seki, Yoshichika; Shinohara, Takenao; Parker, J. D.*; Yashiro, Wataru*; Momose, Atsushi*; Kato, Kosuke*; Kato, Hidemi*; Sadeghilaridjani, M.*; Otake, Yoshie*; Kiyanagi, Yoshiaki*
Journal of the Physical Society of Japan, 86(4), p.044001_1 - 044001_5, 2017/03
Times Cited Count:14 Percentile:64.78(Physics, Multidisciplinary)For the effective phase imaging at pulsed neutron sources, we have designed and developed the multi-colored Talbot-Lau interferometer which works at several wavelengths. At the Energy Resolved Neutron Imaging System RADEN in J-PARC, we demonstrated its operation by observing the visibilities of moire fringes derived from different wavelengths (0.25, 0.50, and 0.75 nm). We also investigated the variation of moire fringes dependent on the wavelength resolution from 18% to 50% and showed the advantage of pulsed beams. At the central wavelength of 0.5 nm, we have succeeded in interferometric imaging for the samples of metal rods made of aluminum, lead, and copper. An absorption grating as an analyzer was fabricated by imprinting of metallic glass for the first time, and showed a clear moire fringe with the high visibility of 68% and a well-controlled shape in comparison with previous ones fabricated by oblique evaporation of gadolinium.
Nishimura, Masahiro; Kamide, Hideki; Otake, Shiro*; Sugiyama, Kenichiro*
Journal of Nuclear Science and Technology, 48(12), p.1420 - 1427, 2011/12
Times Cited Count:6 Percentile:42.22(Nuclear Science & Technology)The purpose of this study is to understand the oxidation behavior of liquid sodium in detail, because it plays an important role in the continuation of the combustion process. Understanding the role of the dendritic oxide in the reaction can be helpful for controlling sodium combustion phenomena, for example, the extinction process. Therefore, this study is a useful contribution to ensuring FR safety.
Nishimura, Masahiro; Kamide, Hideki; Sugiyama, Kenichiro*; Otake, Shiro*
Proceedings of 8th International Topical Meeting on Nuclear Thermal-Hydraulics, Operation and Safety (NUTHOS-8) (CD-ROM), 11 Pages, 2010/10
The purpose of this study is to understand oxidation behavior of sodium precisely for FR safety against sodium combustion. It was recognized that dendritic oxide took an important role for the combustion reaction such as supplying the sodium to the reaction interface. In this study, we proposed a mechanistic model of supplying liquid sodium through the dendritic oxide based on the observation result of the growing behavior of dendritic oxide during combustion. In this model we made an attention to the kinds of chemical compounds. The formation of sodium peroxides can provide the sodium supplying route in the dendritic oxide. On the other hand the formation of sodium monoxide will block sodium supplying. The kinds of chemical compounds were decided by the Gibbs's free energy of thermodynamics in the reaction field such as temperature and oxygen concentration. This mechanistic model can explain the oxidation behavior consistently with the observation results.
Asami, Itsuo*; Fukuta, Shiro*; Kuroyanagi, Satoru*; Otake, Yoshitomo*; Hase, Yoshihiro; Yoshihara, Ryohei; Narumi, Issei
JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 76, 2008/11
no abstracts in English
Nishimura, Masahiro; Kamide, Hideki; Sugiyama, Kenichiro*; Otake, Shiro*
Proceedings of 7th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-7) (CD-ROM), 12 Pages, 2008/10
Liquid sodium is used as the coolant of the fast reactor (FR), because of its high thermal conductivity and wide temperature range of liquid phase. It is superior as thermal medium, however the chemical reactivity with water and oxygen is very high. Hence FR plants have been taking safety measures for these reactions. After the "Monju" sodium leak accident, it is desired that more physical and chemical understanding of reaction phenomena and more mechanistic analysis for the sodium fire from the view point of public acceptance. The purpose of this study is to understand oxidation behavior of a liquid sodium droplet precisely, which is a fundamental reaction of spray fire and is easy to observe the reaction interface. This study is also useful for the establishment of safety criterion to handle the remained non-burning sodium after the accident. The oxidation of a liquid sodium droplet was visualized by using a simple experimental setup and a high speed video camera. A sodium single droplet of ca. 50 mg was made at the tip of a nozzle in a combustion chamber. The oxidation was started by supply of oxygen and nitrogen mixture gas. The initial temperature of sodium droplet and the oxygen fraction in the atmosphere were selected as experimental parameters. It was shown that columnar oxides grew longer as initial temperature of sodium droplet was lower and oxygen fraction was lower. In addition, it was observed that sodium combustion with an orange light emission started from the tip of columnar oxides grown out from the droplet surface. These observations suggest the existence of mechanism that liquid sodium is drawn up from droplet to reaction interface by the capillary force caused in the porous oxides which are formed on the droplet surface.
Takada, Hiroshi; Maekawa, Fujio; Honmura, Shiro*; Yoshida, Katsuhiko*; Teraoku, Takuji*; Meigo, Shinichiro; Sakai, Akio*; Kasugai, Yoshimi; Kanechika, Shuji*; Otake, Hidenori*; et al.
Proceedings of ICANS-XVI, Volume 3, p.1115 - 1125, 2003/07
no abstracts in English
Sato, Fuminori; Kataoka, Shoji; Matsushima, Ryotatsu; Otake, Katsumi*; Shirozu, Hidetomo
no journal, ,
no abstracts in English
Sato, Fuminori; Kataoka, Shoji; Matsushima, Ryotatsu; Otake, Katsumi*; Shirozu, Hidetomo
no journal, ,
no abstracts in English
Asami, Itsuo*; Fukuta, Shiro*; Kuroyanagi, Satoru*; Otake, Yoshitomo*; Hase, Yoshihiro; Yoshihara, Ryohei; Narumi, Issei
no journal, ,
no abstracts in English