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Ishitsuka, Etsuo; Nagasumi, Satoru; Hasegawa, Toshinari; Kawai, Hiromi*; Wakisaka, Shinji*; Nagase, Sota*; Nakamura, Kento*; Yaguchi, Hiroki*; Ishii, Toshiaki; Nakano, Yumi*; et al.
JAEA-Technology 2024-008, 23 Pages, 2024/07
JAEA-Technology-2024-008.pdf:1.69MB
Five people from three universities participated in the 2023 summer holiday practical training with the theme of "Technical development on HTTR". The participants practiced the analysis of HTTR core, the analysis of behavior on loss of forced cooling test, the analysis of Iodine deposition behavior in primary cooling system and the feasibility study of energy storage system for HTGRs. In the questionnaire after this training, there were impressions such as that it was useful as a work experience and some students found it useful for their own research. These impressions suggest that this training was generally evaluated as good.
Nemoto, Takahiro; Fujiwara, Yusuke; Arakawa, Ryoki; Choyama, Yuya; Nagasumi, Satoru; Hasegawa, Toshinari; Yokoyama, Keisuke; Watanabe, Masashi; Onishi, Takashi; Kawamoto, Taiki; et al.
JAEA-Technology 2024-003, 17 Pages, 2024/06
JAEA-Technology-2024-003.pdf:1.91MB
In order to investigate the cause of the increase in differential pressure in the primary helium circulator filter that occurred during the RS-14 cycle, a clogged filter was investigated. As a result of the investigation, deposits caused by silicone oil were confirmed on the surface of the filter element. These results revealed that the cause of filter clogging was silicone oil mixed into the primary system due to performance deterioration of the charcoal filter in the gas circulator of primary helium purification system. As a measure to prevent the recurrence of this event, in addition to the conventional management based on operating hours for replacing of charcoal filter in the gas circulator of primary helium purification system, we have established a new replacement plan for every three years.
Saijo, Tomoaki; Mizuta, Naoki; Hasegawa, Toshinari; Suganuma, Takuro; Shimazaki, Yosuke; Ishihara, Masahiro; Iigaki, Kazuhiko
JAEA-Technology 2024-002, 96 Pages, 2024/06
JAEA-Technology-2024-002.pdf:22.18MB
Nuclear-grade graphite is used for core components of High Temperature Engineering Test Reactor (HTTR) due to excellent heat resistant properties. The physical properties of this graphite change with temperature and neutron irradiation, as well as exhibit complex behavior such as irradiation deformation and creep deformation. Then, stress analysis code has been developed for the graphite. In previous study, the code has been used to evaluate the shutdown stress by residual strain that accumulates with neutron irradiation. However, the effects of change in physical properties such as Young's modulus and thermal expansion-coefficient on shutdown stress have not been fully understood. Therefore, an evaluation model based on a simplified beam model was developed to clarify the effects of changes in physical properties and complex deformations on stresses occurring during operation and reactor shutdown, and to contribute to the development of graphite structures with longer lifetimes. As an application example, the effects of changes on various physical properties on operational and shutdown stresses were clarified for graphite components in the temperature range from 600 to 800
C.
Hasegawa, Toshinari; Nagasumi, Satoru; Nemoto, Takahiro; Nakajima, Kunihiro; Yokoyama, Keisuke; Fujiwara, Yusuke; Arakawa, Ryoki; Iigaki, Kazuhiko; Inoi, Hiroyuki; Kawamoto, Taiki
Proceedings of 2024 International Congress on Advanced in Nuclear Power Plants (ICAPP 2024) (Internet), 10 Pages, 2024/06
The filter element of the primary gas circulators (PGC) in High Temperature engineering Test Reactor (HTTR) and its deposits were investigated by Scanning Electron Microscope (SEM) observation and Energy Dispersive X-ray spectroscopy (EDX) analysis to find the cause of the increase of the filter differential pressure during the operation in 2021. SEM observation showed that the clumpy deposits and fibrous deposits smaller than the filtration pore size and the rod-shaped deposits larger than the pore size were present on the filter element. EDX analysis showed that the clumpy deposits and fibrous deposits could include silicone oil in the primary helium purification system (PHPS) gas circulators and that the rod-shaped deposits were thermal insulators inside of the co-axial double pipes in the primary cooling system. It is considered that silicone oil leaked from the PHPS gas circulators due to deterioration in the absorption performance of the activated charcoal filter. Next, it could be vaporized and reach PGC's filter element after passing through the reactor core. Since those deposits including silicone oil were present over the entire surface of the filter element, the filter differential pressure could be increased due to a reduction in the pore size and a rise in its flow resistance. The thermal insulator was unrelated to filter clogging because it was present mainly in the lower part of the filter element. Therefore, silicone oil could increase the filter differential pressure, and the graphite powder, which is the cause of the previous issue was unrelated.
Hasegawa, Toshinari; Fukaya, Yuji; Ueta, Shohei; Goto, Minoru
Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 5 Pages, 2021/08
Burnable poison (BP) credit concept has been proposed as a criticality safety measure for commercial high temperature gas-cooled reactor (HTGR) fuel fabrication, so we estimated manufacturability of the BP-mixed UO
kernel for the practical use of the concept. As a BP, boron, gadolinium, erbium, and hafnium are investigated. Boron mixed fuel kernels are fabricated by mixing boric acid powder with U
O
powder. In the case of the other BPs, BP nitrate powder is mixed with UO powder. In order to confirm that BP remain in the kernels after the heat treatment processes, thermodynamic equilibrium analysis was performed. Above 450
C, boron would melt and vaporize during the heat treatment processes, so it was found that the boron mixed fuel kernel fabrication is difficult. On the other hand, it was found that gadolinium, erbium, and hafnium would change to solid oxides that do not melt and vaporize even at 2000C, and there was no problem with manufacturability of the BP-mixed fuel kernel.
Isono, Takaaki; Nunoya, Yoshihiko; Ando, Toshinari*; Okuno, Kiyoshi; Ono, Michitaka*; Ozaki, Akira*; Koizumi, Tsutomu*; Otani, Nozomu*; Hasegawa, Takayo*
IEEE Transactions on Applied Superconductivity, 13(2), p.1512 - 1515, 2003/06
Times Cited Count：24 Percentile：70.23(Engineering, Electrical & Electronic)Japan Atomic Energy Research Institute has started development work on a large current conductor using high Tc superconductor (HTS) aiming at a fusion power reactor after the International Thermonuclear Experimental Reactor (ITER). HTS has a capability to produce a magnetic field of higher than 16 T, which is required in such a fusion power reactor. A trial fabrication of a 10-kA 12-T conductor was started using round Ag-alloy sheathed Bi-2212 strands, which has best performance at 4.2K, 16T at present. The conductor has about 34-mm diameter, and is composed of 729 HTS strands. Operating temperature is designed at not only 4 K but also 20K. The conductor sample is indirectly cooled and is solder-coated on the surface to use specific heat of the lead as much as possible, which at 20 K is almost comparable with specific heat of SHe at 4.5K, 0.6MPa. From the tests of the conductor, the fabrication of large HTS conductor and 10kA operation at 12 T and about 12.5 K were successfully performed and the possibility of HTS to use fusion application was demonstrated.
Ando, Toshinari; Kato, Takashi; Ushigusa, Kenkichi; Nishio, Satoshi; Kurihara, Ryoichi; Aoki, Isao; Hamada, Kazuya; Tsuji, Hiroshi; Hasegawa, Mitsuru*; Naito, Shuji*
Fusion Engineering and Design, 58-59, p.13 - 16, 2001/11
Times Cited Count：10 Percentile：58.13(Nuclear Science & Technology)no abstracts in English
Sugimoto, Makoto; ; Isono, Takaaki; Koizumi, Norikiyo; Nakajima, Hideo; Kato, Takashi; Nishi, Masataka; Takahashi, Yoshikazu; Ando, Toshinari; Tsuji, Hiroshi; et al.
IEEE Transactions on Magnetics, 32(4), p.2328 - 2331, 1996/07
Times Cited Count：6 Percentile：50.61(Engineering, Electrical & Electronic)no abstracts in English
; ; ; Ando, Toshinari; Fujisawa, Noboru; Hasegawa, Mitsuru*; ; ; ; Iida, Hiromasa; et al.
JAERI-M 88-010, 206 Pages, 1988/02
no abstracts in English
Hashimoto, Haruki*; Sawa, Kazuhiro*; Hasegawa, Toshinari; Nagasumi, Satoru; Ishitsuka, Etsuo; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
