Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Hamamoto, Shimpei; Ohashi, Hirofumi; Iigaki, Kazuhiko; Shimazaki, Yosuke; Ono, Masato; Shimizu, Atsushi; Ishitsuka, Etsuo
Proceedings of 2021 International Congress on Advances in Nuclear Power Plants (ICAPP 2021) (USB Flash Drive), 6 Pages, 2021/10
Since the HTGR has a large amount of graphite material in the core, it is necessary to assume an accident in which the reactor pressure boundary is damaged and air flows into the core. It is important to state that at the time of this accident, graphite does not burn and the accident does not develop due to the heat of oxidation reaction. Therefore, in this study, in order to evaluate the combustibility of graphite materials, we propose a method to compare the calorific value and heat removal amount of the material. When calculating the calorific value, the structural material of HTTR, a high-temperature gas reactor in Japan, was used as a reference. The amount of air in contact with the structural material is a value determined from the chimney effect. The amount of heat release is the sum of convection and radiation. As a result of comparing the heat generation amount with the heat removal amount, it was shown that the heat release amount was always larger than the heat generation amount. This result shows that the graphite material does not depend on the state at the time of the air inflow accident, the temperature decreases and does not burn. It is important to clearly explain the non-flammability of graphite materials when deciding how to deal with severe accidents in HTGRs. This quantitative evaluation method based on a simple theory is considered useful.
Sato, Hiroyuki; Ohashi, Hirofumi; Nakagawa, Shigeaki
Mechanical Engineering Journal (Internet), 4(3), p.16-00495_1 - 16-00495_11, 2017/06
This paper intends to propose a practical solution to protect the HTR from severe oxidation against air ingress accidents without reliance on subsystems. Firstly, a change is made to the center reflector structure to minimize temperature difference during the accident condition in order to reduce buoyancy-driven natural circulation in the reactor. Secondly, a modified structure of the upper reflector is suggested to prevent massive air ingress against a rupture in standpipes. As a preliminary study, a numerical analysis is performed for a typical prismatic-type HTGR. The results showed that amount of air ingress into the reactor can be significantly reduced with practical changes to local structure in the reactor.
Sato, Hiroyuki; Ohashi, Hirofumi; Nakagawa, Shigeaki
Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 8 Pages, 2016/06
This paper intends to propose a practical solution to protect HTGR from severe oxidation against air ingress accidents without reliance on subsystems. Firstly, a change is made to the center reflector structure to minimize temperature difference during the accident condition in order to reduce buoyancy-driven natural circulation in the reactor. Secondly, a modified structure of the upper reflector is suggested to prevent massive air ingress against a rupture in standpipes. As a preliminary study, a numerical analysis is performed for a typical prismatic-type HTGR to study the effectiveness of the proposed design concept using simplified lumped element models. The results showed that amount of air ingress into the reactor can be significantly reduced with practical changes to local structure in the reactor.
shell gap in 
NeBelleguic, M.*; Azaiez, F.*; Dombr
di, Zs.*; Sohler, D.*; Lopez-Jimenez, M. J.*; Otsuka, Takaharu*; Saint-Laurent, M. G.*; Sorlin, O.*; Stanoiu, C.*; Utsuno, Yutaka; et al.
Physical Review C, 72(5), p.054316_1 - 054316_7, 2005/11
Times Cited Count：41 Percentile：89.52(Physics, Nuclear)no abstracts in English
Ouchi, Nobuo; Akaoka, Nobuo*; Asano, Hiroyuki*; Chishiro, Etsuji; Hasegawa, Kazuo; Takeda, Osamu*; Yoshikawa, Hiroshi; Matsuoka, Masanori*; Otani, Toshihiro*; Kako, Eiji*; et al.
Proceedings of 21st International Linear Accelerator Conference, p.488 - 490, 2003/00
Development of a superconducting proton linac is in progress in collaboration with KEK. In order to demonstrate cavity performance and to study stable accelerating field in a pulsed operation, a 600MHz superconducting cryomodule has been fabricated. The cryomodule includes two 5-cell superconducting cavities of 
=0.6 and is designed to perform 2K operation. Cold tests of the cryomodule have been performed at the temperature of 4K and 2K. In the tests, heat leak to the cavities, loaded quality factors, tuning sensitivities, frequency shifts against helium vessel pressure and Lorentz force detuning of the cavities were measured. Most of the measured data agreed with their design values, except for the heat leak and the Lorentz force detuning. As the preliminary horizontal test of the cryomodule, high power RF test has been also performed, where the surface peak fields of 10 and 16 MV/m were achieved in CW and pulsed operation, respectively. Now, the optimization of the RF control system is in progress to demonstrate stable accelerating field in a pulsed operation.
Shibata, Mitsuhiko; Takase, Kazuyuki; Watanabe, Hironori; Akimoto, Hajime
Fusion Engineering and Design, 63-64, p.217 - 222, 2002/12
Times Cited Count：5 Percentile：34.51(Nuclear Science & Technology)no abstracts in English
Takase, Kazuyuki; Ose, Yasuo*; Akimoto, Hajime
Fusion Engineering and Design, 63-64, p.429 - 436, 2002/12
Times Cited Count：5 Percentile：34.51(Nuclear Science & Technology)no abstracts in English
Ose, Yasuo*; Takase, Kazuyuki; Yoshida, Hiroyuki; Akimoto, Hajime
Proceedings of 10th International Conference on Nuclear Engineering (ICONE 10) (CD-ROM), 8 Pages, 2002/00
no abstracts in English
Kurihara, Ryoichi; Ajima, Toshio*; Ueda, Shuzo; Seki, Yasushi
Journal of Nuclear Science and Technology, 38(7), p.571 - 576, 2001/07
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)no abstracts in English
Miyata, Seiki*; Osamura, Kozo*; Suzuki, Junichi
Journal of the Physical Society of Japan, 70(7), p.2098 - 2101, 2001/07
Times Cited Count：0 Percentile：0.01(Physics, Multidisciplinary)no abstracts in English
Takase, Kazuyuki; Ose, Yasuo*; Akimoto, Hajime
Fusion Technology, 39(2-Part.2), p.1050 - 1055, 2001/03
no abstracts in English
Takase, Kazuyuki; Ose, Yasuo*; Shibata, Mitsuhiko; Akimoto, Hajime
Dai-38-Kai Nihon Dennetsu Shimpojiumu Koen Rombunshu, p.641 - 642, 2001/00
no abstracts in English
Takase, Kazuyuki
Fusion Engineering and Design, 51-52(Part.B), p.631 - 639, 2000/11
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)no abstracts in English
Takase, Kazuyuki; Ose, Yasuo*; Akimoto, Hajime
Nihon Kikai Gakkai Ryutai Kogaku Bumon Koenkai 2000 Koen Rombunshu (CD-ROM), 4 Pages, 2000/09
no abstracts in English
Takeda, Tetsuaki; Hishida, Makoto*
Nuclear Engineering and Design, 200(1-2), p.251 - 259, 2000/08
Times Cited Count：27 Percentile：82.56(Nuclear Science & Technology)no abstracts in English
Takase, Kazuyuki
Nihon Kikai Gakkai 2000-Nendo Nenji Taikai Koen Rombunshu, 1, p.607 - 608, 2000/00
no abstracts in English
Takase, Kazuyuki; Ose, Yasuo*; Suzuki, Takayuki*; Akimoto, Hajime
Nihon Kikai Gakkai Yamanashi Koenkai Koen Rombunshu (000-4), p.173 - 174, 2000/00
no abstracts in English
Takase, Kazuyuki; Kunugi, Tomoaki*; Yamazaki, Seiichiro*; *
Fusion Technology, 34(3), p.640 - 644, 1998/11
no abstracts in English
Takase, Kazuyuki; Kunugi, Tomoaki*; Yamazaki, Seiichiro*; *
Dai-35-Kai Nihon Dennetsu Simpojiumu Koen Rombunshu, p.801 - 802, 1998/05
no abstracts in English
