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Nishida, Akemi; Choi, B.; Kang, Z.; Shiomi, Tadahiko; Iigaki, Kazuhiko; Yamakawa, Koki*
Transactions of the 28th International Conference on Structural Mechanics in Reactor Technology (SMiRT28) (Internet), 10 Pages, 2025/08
Our research and development are aimed at improving the accuracy of the three-dimensional seismic analysis of nuclear buildings to better understand their three-dimensional seismic behavior in response to enhanced regulatory requirements on impact assessment against external events such as earthquakes. In 2019, we constructed a large-scale observation system for the High Temperature Engineering Test Reactor (HTTR) building of the Japan Atomic Energy Agency (JAEA) in collaboration with the Nuclear Regulation Authority (NRA) and JAEA. Since then, we also conducted several excitation tests by the ACROSS system and obtained observation record at many accelerometers using the observation system. These records are important since the excitation source is clearly defined unlike earthquake's uncertain transmission pathway. In this paper, we focus mainly on the vibration characteristics of the entire building and report on these observation records and the characteristics, such as the dominant frequencies and corresponding three-dimensional deformation modes.
Yamakawa, Koki*; Hiramatsu, Masako*; Moritani, Hiroshi*; Iiba, Masanori*; Nishida, Akemi; Shiomi, Tadahiko; Choi, B.; Iigaki, Kazuhiko
Transactions of the 28th International Conference on Structural Mechanics in Reactor Technology (SMiRT28) (Internet), 9 Pages, 2025/08
To understand the three-dimensional seismic behavior of nuclear buildings, the Nuclear Regulation Authority (NRA) and the Japan Atomic Energy Agency (JAEA) have been conducting research and development aimed at improving the accuracy of three-dimensional seismic analysis methods for nuclear buildings. A large-scale observation system was constructed in the High Temperature engineering Test Reactor (HTTR) building of JAEA, enabling seismic observation and artificial wave excitation. Using this system, vibration characteristics of the HTTR building have been analyzed based on both seismic observation records and analyses using a three-dimensional seismic analysis model of the HTTR building. This paper reports on the vibration characteristics of the HTTR building obtained from the analysis of seismic observation records, as well as on the improvements made to the three-dimensional finite element model and the results of simulation analyses using artificial waves. In particular, this paper presents the results of an analysis of the Fourier spectral ratio at the first floor of the HTTR building based on seismic records, and discusses the dominant frequencies and acceleration modes of the superstructure.
Choi, B.; Nishida, Akemi; Shiomi, Tadahiko; Kawata, Manabu; Iigaki, Kazuhiko; Yamakawa, Koki*
Transactions of the 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 8 Pages, 2024/03
no abstracts in English
Nishida, Akemi; Kawata, Manabu; Choi, B.; Kunitomo, Takahiro; Shiomi, Tadahiko; Iigaki, Kazuhiko; Yamakawa, Koki*
Transactions of the 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 10 Pages, 2024/03
no abstracts in English
Yamakawa, Koki*; Moritani, Hiroshi*; Saruta, Masaaki*; Iiba, Masanori*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
Transactions of the 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 10 Pages, 2024/03
no abstracts in English
Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Yamazaki, Hiroaki*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 6 Pages, 2021/08
Several large-scale earthquakes have occurred, such as the Niigataken Chuetsu-oki Earthquake in 2007 and the 2011 off-the-Pacific coast of Tohoku Earthquake. Therefore, a three-dimensional (3D) finite element model to evaluate the local response of the reactor building is currently being developed for seismic response analysis. In order to refine the 3D finite element model, it is important to verify the correspondence to the seismic observation behaviors. In this study, the authors analyze the basic response characteristics, such as the natural frequencies and modes of the reactor building, and evaluate the effects of the amplitude of the seismic excitation on the response characteristics based on seismic observation records. This is done to clarify the behavior of a reactor building during earthquakes. These analyses will assist in quantitatively evaluating the correlation between the natural frequency of the building and the amplitude of the seismic excitation. Furthermore, the ratios of rotational displacement and displacement caused by building deformation for natural modes are discussed.
Yamamoto, Kazami; Yamakawa, Emi*; Takayanagi, Tomohiro; Miki, Nobuharu*; Kamiya, Junichiro; Saha, P. K.; Yoshimoto, Masahiro; Yanagibashi, Toru*; Horino, Koki*; Nakanoya, Takamitsu; et al.
ANS RPSD 2018; 20th Topical Meeting of the Radiation Protection and Shielding Division of ANS (CD-ROM), 9 Pages, 2018/08
The existing beam power of the J-PARC Rapid Cycling Synchrotron is up to 500 kW, and higher radiation doses are concentrated in the injection area. These activations are caused by the interaction between the foil and the beam. To reduce dose exposure to workers near the injection point, we study a new design of the injection scheme. Experience has shown that eddy currents are generated in the metal flange near the magnet owing to the pulsed magnetic field, and the temperature exceeds 100 degrees C. The shield installed in the new injection system needs to have a layer structure, in which an insulator is inserted between iron shields to reduce the eddy current. From the results of the shielding calculation, even if 1 mm of polyethylene was inserted between two 9-mm-thick SUS 316 plates, which serve as shielding material, the shielding performance was reduced only about 5%, and we confirmed that it would function well.
Tsuchiya, Takashi*; Yamakawa, Koki*; Saruta, Masaaki*; Iiba, Masanori*; Hiramatsu, Masako*; Nishida, Akemi; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Yamakawa, Koki*; Tsuchiya, Takashi*; Hiramatsu, Masako*; Moritani, Hiroshi*; Saruta, Masaaki*; Iiba, Masanori*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Shiomi, Tadahiko; Nishida, Akemi; Choi, B.; Kawata, Manabu; Iigaki, Kazuhiko; Yamakawa, Koki*
no journal, ,
no abstracts in English
Yamakawa, Koki*; Tsuchiya, Takashi*; Hiramatsu, Masako*; Moritani, Hiroshi*; Saruta, Masaaki*; Iiba, Masanori*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Nishida, Akemi; Shiomi, Tadahiko; Kunitomo, Takahiro; Kawata, Manabu; Iigaki, Kazuhiko; Yamakawa, Koki*
no journal, ,
no abstracts in English
Nishida, Akemi; Kawata, Manabu; Choi, B.; Iigaki, Kazuhiko; Yamakawa, Koki*
no journal, ,
no abstracts in English
Kawata, Manabu; Nishida, Akemi; Choi, B.; Iigaki, Kazuhiko; Yamakawa, Koki*
no journal, ,
no abstracts in English
Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko; Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Yamazaki, Hiroaki*
no journal, ,
no abstracts in English
Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Yamazaki, Hiroaki*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Iiba, Masanori*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Moritani, Hiroshi*; Yamakawa, Koki*; Saruta, Masaaki*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Shiomi, Tadahiko; Nishida, Akemi; Choi, B.; Kang, Z.; Iigaki, Kazuhiko; Yamakawa, Koki*
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no abstracts in English
