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Nagoshi, Yasuto*; Fukahori, Takuya*; Okada, Hiroshi*; Takahashi, Akiyuki*; Shimodaira, Masaki; Ueda, Takashi*; Ogawa, Takuya*; Yashirodai, Kenji*; Takahashi, Yukio*; Ohata, Mitsuru*
Transactions of the 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 9 Pages, 2024/03
no abstracts in English
Ando, Masaki; Nakahara, Yukio; Tsuda, Shuichi; Yoshida, Tadayoshi; Matsuda, Norihiro; Takahashi, Fumiaki; Mikami, Satoshi; Kinouchi, Nobuyuki; Sato, Tetsuro*; Tanigaki, Minoru*; et al.
Journal of Environmental Radioactivity, 139, p.266 - 280, 2015/01
Times Cited Count：53 Percentile：83(Environmental Sciences)A series of car-borne surveys using the KURAMA and KURAMA-II systems was conducted in a wide area in eastern Japan from June 2011 to December 2012 to evaluate the distribution of air dose rates around the Fukushima Dai-ichi Nuclear Power Plant, and to determine the time-dependent trend of decrease in air dose rates. An automated data processing system was established, which enables analyses of large amounts of data obtained with the use of about 100 units of the measurement system in a short time. The initial data for studying the migration status of radioactive cesium was obtained in the first survey, followed by the other car-borne surveys having wider measurement ranges. Comparing the measured air dose rates obtained in each survey, it was found that the decreasing trend of air dose rates measured through car-borne surveys was larger than that expected from the physical decay of radioactive cesium and that measured using NaI (Tl) survey meters around the road.
Nakasone, Yuji*; Sato, Kazuyoshi; Takahashi, Yukio*
Proceedings of 2010 ASME Pressure Vessels and Piping Conference (PVP 2010) (CD-ROM), 5 Pages, 2010/07
no abstracts in English
Isobe, Nobuhiro*; Sukekawa, Masayuki*; Nakayama, Yasunari*; Date, Shingo*; Otani, Tomomi*; Takahashi, Yukio*; Kasahara, Naoto; Shibamoto, Hiroshi*; Nagashima, Hideaki*; Inoue, Kazuhiko*
Nuclear Engineering and Design, 238(2), p.347 - 352, 2008/02
Times Cited Count：21 Percentile：78.77(Nuclear Science & Technology)The effect of ratcheting on fatigue strength was investigated in order to rationalize the strain limit as a design criterion of commercialized fast reactor systems. Ratcheting fatigue tests were conducted at 550
C. Duration of the ratchet straining was set for a certain number of strain cycles taking the loading condition of fast reactors into account, and the number of cycles for strain accumulation was defined as the ratchet-expired cycle. Fatigue lives decrease as the accumulated strain by ratcheting increases. Fatigue life reduction was negligible when the maximum mean stress was less than 25 MPa, corresponding to an accumulated strain of 2.2 percent. Accumulated strain is limited to 2 percent in the present design guidelines and this strain limit is considered effective to avoid reducing fatigue life by ratcheting. Micro-crack growth behaviors were also investigated in these tests in order to discuss the life reduction mechanisms in ratcheting conditions.
Wakai, Takashi; Takahashi, Yukio*
Nihon Kikai Gakkai 2007-Nendo Nenji Taikai Koen Rombunshu, Vol.1, p.401 - 402, 2006/09
This paper describes metallurgical observation and analysis results for the aged welds made of Gr.91 and Gr.122 steels. Much more coarse carbides were observed by SEM in the fine grain heat affected zone of the welds than in the base metal and coarse carbides increased with aging. However, extracted residue analyses showed that the total amount of precipitations did not depend on regions and did not increase with aging. Therefore, the carbides which had precipitated in the early stage of aging cohered and grew mainly on the prior austenite grain boundaries, as far as the welds were subjected to stress free isothermal aging for 6,000 hours.
Shibamoto, Hiroshi; Inoue, Kazuhiko*; Takahashi, Yukio*; Nakamura, Kyotada*; Kasahara, Naoto; Nakayama, Yasunari*
no journal, ,
no abstracts in English
Takahashi, Yukio*; Kasahara, Naoto; Shibamoto, Hiroshi*; Inoue, Kazuhiko*
no journal, ,
no abstracts in English
Kamishima, Yoshio*; Asayama, Tai; Takahashi, Yukio*
no journal, ,
no abstracts in English
Nishimura, Arata*; Nakajima, Hideo; Nakasone, Yuji*; Takahashi, Yukio*; Irie, Hirosada*; Suzuki, Tetsuya*
no journal, ,
no abstracts in English
Nakasone, Yuji*; Takahashi, Yukio*; Sato, Kazuyoshi; Nishimura, Arata*; Suzuki, Tetsuya*; Irie, Hirosada*; Nakahira, Masataka*
no journal, ,
no abstracts in English
