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Banno, Masaki*; Funatani, Shumpei*; Takamatsu, Kuniyoshi
Yamanashi Koenkai 2022 Koen Rombunshu (CD-ROM), 6 Pages, 2022/10
A fundamental study on the safety of a passive cooling system for the reactor pressure vessel (RPV) with radiative cooling is conducted. The object of this study is to demonstrate that passive RPV cooling system with radiative cooling is extremely safe and reliable even in the event of natural disasters. Therefore, an experimental apparatus, which is about 1/20 scale of the actual cooling system, was fabricated with several stainless steel containers. The surface of the heating element in the experimental apparatus simulates the surface of the RPV, and the heating element generates natural convection and radiation. As a result of the experiments, we succeeded in visualizing the natural convection in the experimental apparatus in detail.
Nakagaki, Keita; Yamauchi, Toshihiko; Kanno, Yoshinori*; Kobayashi, Seiji*; Takemoto, Ryo*
Japanese Journal of Applied Physics, 47(3), p.1745 - 1747, 2008/03
Times Cited Count：2 Percentile：9.81(Physics, Applied)The CVD system with internal RF multi-turn antenna coil for 27.12 MHz was developed, and to study the transition between CCP (Capacitively Coupled Plasma) and ICP (Inductively Coupled Plasma). The observed transition was classified into three types of transition: the standard transition, the direct transition without the CCP-mode and the repeated transition. The power boundary condition for each transition which is associated with the gas pressure and RF power is presented. Here, the standard transition was mainly presented: The transition time was 8 
s at 10 Pa, which became longer with the increase of gas pressure. The increments of electron temperature and density by the transition into ICP were three times and double figures higher respectively.
Nakagaki, Keita; Yamauchi, Toshihiko; Kanno, Yoshinori*; Kobayashi, Seiji*
Japanese Journal of Applied Physics, 47(1), p.797 - 799, 2008/01
Times Cited Count：1 Percentile：5.16(Physics, Applied)The CVD system by 27.12 MHz RF heating plasma discharge was developed to investigate the synthesis of the advanced ceramics, particularly diamond. Our system was unique, whose four turns RF antenna coil was installed inside of chamber. Here, we found the interesting physical behavior for the first time which the charge coupled plasma (CCP) changed to the inductively coupled plasma (ICP) suddenly at the threshold power. The plasma characteristics which were measured by the double probe were Te
10 eV and ne 10E11 cm
suitable for the dissociation. No impurity was observed in plasma, judging from the spectroscopic measurement. The ball-like diamond was synthesized on the silicon (Si) substrate by the low power RF heating plasma.
Ichimiya, Koichi*; Takeda, Tetsuaki; Uemura, Takuya*; Norikuni, Tetsuya*
Nihon Kikai Gakkai Rombunshu, B, 72(723), p.2747 - 2752, 2006/11
no abstracts in English
Takase, Kazuyuki; Kitamura, Tatsuaki*; Kume, Etsuo; Ichimiya, Koichi*; Komada, Ichiro*
Nihon Kikai Gakkai Kanto Shibu Yamanashi Koenkai (2003) Koen Rombunshu, No.030-4, p.77 - 78, 2003/00
no abstracts in English
Itakura, Keiji*; Kuroda, Yasuo*; Kan, Yoshihiko*; Kobayashi, Shinichiro*; Ogi, Katsumi*; Nishijima, Naotaka*; Sato, Teruyoshi*
PNC TJ121 79-03, 111 Pages, 1979/02
no abstracts in English
Takeda, Tetsuaki; Ichimiya, Koichi*; Yamauchi, Daiki*
no journal, ,
A technology development of a hydrogen production system by a nuclear heat is being performed as a heat application system of a high-temperature gas cooled reactor in the Japan Atomic Energy Research Institute. The objective of this study is to clarify heat transfer characteristics of the steam reformer inserted metallic wire with high porosity. An experiment has been performed using a double coaxial channel and single channel with metallic wire to obtain the heat transfer characteristics. From the results obtained in this experiment, it seems to be probable that an enhancement of heat transfer method using metallic wire inserts is further improved under the high temperature conditions in efficiency as compared with the conventional reformer.
Ichimiya, Koichi*; Takeda, Tetsuaki; Yamauchi, Daiki*
no journal, ,
A hydrogen production system using nuclear heat is performed as a heat application system of the HTTR in JAERI. In the present studies heat transfer improvement in the reformer tube is examined using a porous material with high porosity. In the first report, the heat transfer and flow characteristics of an annular tube were examined experimentally to obtain the basic data. These results were compared with the convenient data.
Yamauchi, Toshihiko; Nakagaki, Keita*; Kanno, Yoshinori*; Kobayashi, Seiji*; Saigusa, Mikio*; Takemoto, Ryo*; Yamashita, Naohito*; Kawashima, Tomohiro*
no journal, ,
no abstracts in English
Yamauchi, Toshihiko; Nakagaki, Keita; Kanno, Yoshinori*; Kobayashi, Seiji*; Takemoto, Ryo*
no journal, ,
no abstracts in English
Takeda, Tetsuaki; Tochio, Daisuke; Inaba, Yoshitomo; Ichimiya, Koichi*; Nishio, Hitoshi*
no journal, ,
Safety demonstration tests using the HTTR (High Temperature Engineering Test Reactor) are being performed to verify the inherent safety features and to validate the numerical code for the safety assessment of the VHTR (Very High Temperature Reactor). The test of loss of coolant flow as one of safety demonstration tests is carried out by tripping of the helium gas circulators. The objective of this study is to evaluate the temperature distribution of the reactor pressure vessel (RPV) and the vessel cooling system (VCS) during the loss of coolant flow. The temperature distribution of the RPV and surrounding concrete structure were obtained using a commercially available analysis code STAR-CD. The effect of thermal radiation from the RPV was evaluated using the analytical and experimental results. It was found that it is important to take account of the effect of thermal radiation in the transient analysis to evaluate the temperature change of the concrete accurately.
Takeda, Tetsuaki; Nishio, Hitoshi*; Ichimiya, Koichi*
no journal, ,
Safety demonstration tests using the HTTR (High Temperature Engineering Test Reactor) are being performed to verify the inherent safety features and to validate the numerical code for the safety assessment of the VHTR (Very High Temperature Reactor). The test of loss of coolant flow as one of safety demonstration tests is carried out by tripping of the helium gas circulators. The objective of this study is to evaluate the temperature distribution of the reactor pressure vessel (RPV) and the vessel cooling system (VCS) during the loss of coolant flow. The temperature distribution of the RPV and surrounding concrete structure were obtained using a commercially available analysis code STAR-CD. The effect of thermal radiation from the RPV was evaluated using the analytical and experimental results. It was found that the RPV and surrounding concrete structure were cooled enough by the VCS in the case of loss of coolant flow.
Takeda, Tetsuaki; Nishio, Hitoshi*; Ichimiya, Koichi*
no journal, ,
Safety demonstration tests using the HTTR (High Temperature Engineering Test Reactor) are being performed to verify the inherent safety features and to validate the numerical code for the safety assessment of the VHTR (Very High Temperature Reactor). The test of loss of coolant flow as one of safety demonstration tests is carried out by tripping of the helium gas circulators. The objective of this study is to evaluate the temperature distribution of the reactor pressure vessel (RPV) and the vessel cooling system (VCS) during the loss of coolant flow. The temperature distribution of the RPV and surrounding concrete structure were obtained using a commercially available analysis code STAR-CD. It is necessary to consider the effect of thermal radiation from the RPV for evaluation of temperature of the VCS and concrete vessel.
Yamauchi, Toshihiko; Nakagaki, Keita; Kanno, Yoshinori*; Kobayashi, Seiji*; Takemoto, Ryo*
no journal, ,
The CVD system with internal RF multi-turn antenna coil for 27.12 MHz was developed, and to study the transition between CCP (Capacitively Coupled Plasma) and ICP (Inductively Coupled Plasma). The observed transition was classified into three types of transition: the standard transition, the direct transition with the mixed-mode and the repeated transition. The power boundary condition for each transition which is associated with the gas pressure and RF power is presented. Here, the standard transition was mainly presented: The transition time was 8 microsec at 10 Pa, which became longer with the increase of gas pressure. The increments of electron temperature and density by the transition into ICP were three times and double figures higher respectively.
Yamauchi, Toshihiko; Nakagaki, Keita; Kanno, Yoshinori*; Kobayashi, Seiji*; Takemoto, Ryo*
no journal, ,
no abstracts in English
Kawata, Keiji*; Hanawa, Takehisa*; Hiroki, Akihiro; Nagasawa, Naotsugu; Taguchi, Mitsumasa; Suzuki, Masahiko*; Koguchi, Toshio*
no journal, ,
no abstracts in English
Takamatsu, Kuniyoshi; Funatani, Shumpei*; Banno, Masaki*
no journal, ,
After Fukushima Daiichi nuclear disaster, a cooling system to prevent core damage became more important from the perspective of defense in depth. Therefore, a new, highly efficient RCCS with passive safety features without a requirement for electricity and mechanical drive is proposed. Employing the air as the working fluid and the ambient air as the ultimate heat sink, the new RCCS design strongly reduces the possibility of losing the heat sink for decay heat removal. The RCCS can always stably and passively remove a part of the released heat at the rated operation and the decay heat after reactor shutdown. Specifically, the decay heat can be passively removed for a long time, even forever if the heat removal capacity of the RCCS is sufficient.
