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Naoe, Takashi; Futakawa, Masatoshi; Shobu, Takahisa; Wakui, Takashi; Kogawa, Hiroyuki; Takeuchi, Hirotsugu*; Kawai, Masayoshi*
Journal of Nuclear Science and Technology, 45(7), p.698 - 703, 2008/07
Times Cited Count：12 Percentile：59.34(Nuclear Science & Technology)Liquid-mercury target systems for MW-class spallation neutron sources are being developed in the world. At the moment the proton beam hits the target, pressure waves are generated in the mercury because of the abrupt heat deposition. The pressure waves interact with the target vessel leading to negative pressure that may cause cavitation along the vessel wall. Localized impacts by micro-jets and/or shock waves which are caused by cavitation bubble collapse impose pitting damage on the vessel wall. Bubble collapse behavior was observed by using a high-speed video camera, as well as simulated numerically. Localized impact due to cavitation bubble collapse was quantitatively estimated through comparison between numerical simulation and experiment. A novel surface treatment technique which consists of carburizing and nitriding processes was developed and the treatment condition was optimized to mitigate the pitting damage due to localized impacts.
Naoe, Takashi; Kogawa, Hiroyuki; Wakui, Takashi; Futakawa, Masatoshi; Takeuchi, Hirotsugu*
Zairyo, 57(6), p.576 - 582, 2008/06
A liquid mercury target system for MW-class spallation neutron source is installed in J-PARC. High power proton beams bombard the mercury at 25 Hz, the mercury target vessel suffers the repeated stress due to the pressure waves induced by thermal expansion of the mercury. Cavitation will be generated in the propagation of pressure waves, and pitting damage will be formed on the inner wall of the target vessel by the cavitation bubble collapse. In previous research, it was confirmed that the surface hardening treatment is effective to suppress the pitting damage at some level, although crack and/or separation occurred due to poor interface strength. A novel surface modification technique was developed based on the previous research. The bending fatigue tests on modified stainless steels with pitting damage were performed. As results, damage suppression and fatigue limit improvement due to the modification were confirmed.
Futakawa, Masatoshi; Naoe, Takashi; Wakui, Takashi; Kogawa, Hiroyuki; Takeuchi, Hirotsugu*
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Takeuchi, Yukio*; Taniguchi, Keisuke*; Arai, Hirotsugu*; Yoshita, Hirofumi*; Fujita, Kazuki*; Takahashi, Yusuke*; Kuramoto, Takayuki*; Nomura, Naoki*; Hagiwara, Hiroki; Dohi, Terumi; et al.
no journal, ,
no abstracts in English
Futakawa, Masatoshi; Naoe, Takashi; Kogawa, Hiroyuki; Takeuchi, Hirotsugu*; Kawai, Masayoshi*
no journal, ,
no abstracts in English
Ichihara, Hirotsugu*; Katsuki, Kenta*; Arai, Tsuyoshi*; Watanabe, So; Sano, Yuichi; Takeuchi, Masayuki
no journal, ,
no abstracts in English
