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Muto, Keitaro; Hamano, Daisuke; Kawabata, Mamoru; Tabakoya, Yasuhiro; Yanai, Chisato
E-Journal of Advanced Maintenance (Internet), 11(2), p.86 - 91, 2019/09
Gas sampling type sodium small leak detector, SID, Sodium Ionization Detector, a gas sampling detector installed to monitor small sodium leak in the Prototype Fast Breeder Reactor Monju, had been operated since it's system start up test through to the 40% reactors output test, It's use was terminated in April, 2018. SID showed some indication variations during its operation period, and necessary measures were implemented. As a result, the SID system maintained its functions without any critical malfunction until the end of its operation.
Minami, Ryutaro*; Kariya, Tsuyoshi*; Imai, Tsuyoshi*; Numakura, Tomoharu*; Endo, Yoichi*; Nakabayashi, Hidetaka*; Eguchi, Taku*; Shimozuma, Takashi*; Kubo, Shin*; Yoshimura, Yasuo*; et al.
Nuclear Fusion, 53(6), p.063003_1 - 063003_7, 2013/06
Minami, Ryutaro*; Kariya, Tsuyoshi*; Imai, Tsuyoshi*; Numakura, Tomoharu*; Endo, Yoichi*; Nakabayashi, Hidetaka*; Eguchi, Taku*; Shimozuma, Takashi*; Kubo, Shin*; Yoshimura, Yasuo*; et al.
Nuclear Fusion, 53(6), p.063003_1 - 063003_7, 2013/06
Times Cited Count：12 Percentile：47.21(Physics, Fluids & Plasmas)Muto, Keitaro
Nihon Hozen Gakkai Dai-7-Kai Gakujutsu Koenkai Yoshishu, p.235 - 237, 2010/07
Monju is sodium cooled fast breeder reactor. Monju resumed operations on May 5th, 2010 after an intermission for about 14 years following a sodium leak accident. During the shut-down period, sodium system was operated and there were some troubles of sodium leak detectors. To improve leak detectors performance and reliability, detectors modification and improved maintenance activities were applied. For example, a contact type sodium leak detector (CLD) in the secondary sodium system was modified to increase to ion-migration resistance and periodical insulation measurement was added to the maintenance activities. Based on the maintenance and operation experience and the technology development will be reflected to the improvement of the performance and reliability of sodium leak detectors.
Kariya, Tsuyoshi*; Minami, Ryutaro*; Imai, Tsuyoshi*; Sakamoto, Keishi; Kubo, Shin*; Shimozuma, Takashi*; Takahashi, Hiromi*; Ito, Satoshi*; Muto, Takashi*; Mitsunaka, Yoshika*; et al.
Fusion Science and Technology, 55(2T), p.91 - 94, 2009/02
Times Cited Count：11 Percentile：59.65(Nuclear Science & Technology)Motojima, Osamu*; Yamada, Hiroshi*; Komori, Akio*; Oyabu, Nobuyoshi*; Muto, Takashi*; Kaneko, Osamu*; Kawahata, Kazuo*; Mito, Toshiyuki*; Ida, Katsumi*; Imagawa, Shinsaku*; et al.
Nuclear Fusion, 47(10), p.S668 - S676, 2007/10
Times Cited Count：34 Percentile：73.64(Physics, Fluids & Plasmas)The performance of net-current free heliotron plasmas has been developed by findings of innovative operational scenarios in conjunction with an upgrade of the heating power and the pumping/fuelling capability in the Large Helical Device (LHD). Consequently, the operational regime has been extended, in particular, with regard to high density, long pulse length and high beta. Diversified studies in LHD have elucidated the advantages of net-current free heliotron plasmas. In particular, an internal diffusion barrier (IDB) by a combination of efficient pumping of the local island divertor function and core fuelling by pellet injection has realized a super dense core as high as 5
10
m
, which stimulates an attractive super dense core reactor. Achievements of a volume averaged beta of 4.5% and a discharge duration of 54 min with a total input energy of 1.6 GJ (490 kW on average) are also highlighted. The progress of LHD experiments in these two years is overviewed by highlighting IDB, high-beta and long pulse.
Motojima, Osamu*; Yamada, Hiroshi*; Komori, Akio*; Oyabu, Nobuyoshi*; Kaneko, Osamu*; Kawahata, Kazuo*; Mito, Toshiyuki*; Muto, Takashi*; Ida, Katsumi*; Imagawa, Shinsaku*; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 12 Pages, 2007/03
The performance of net-current free Heliotron plasmas has been developed by findings of innovative operational scenarios in conjunction with an upgrade of the heating power and the pumping/fueling capability in the Large Helical Device (LHD). Consequently, the operational regime has been extended, in particular, with regard to high density, long pulse length and high beta. Diversified studies in LHD have elucidated the advantages of net-current free heliotron plasmas. In particular, an Internal Diffusion Barrier (IDB) by combination of efficient pumping of the local island divertor function and core fueling by pellet injection has realized a super dense core as high as 510m, which stimulates an attractive super dense core reactor. Achievements of a volume averaged beta of 4.5 % and a discharge duration of 54-min. with a total input energy of 1.6 GJ (490 kW in average) are also highlighted. The progress of LHD experiments in these two years is overviewed with highlighting IDB, high 
and long pulse.
Ueda, Shuzo; Kikuchi, Mitsuru; Kimura, Toyoaki; Kunugi, Tomoaki; Kuriyama, Masaaki; Tsuchiya, Kunihiko; Masaki, Kei; Kaneko, Osamu*; Sudo, Shigeru*; Muto, Kei*
Purazuma, Kaku Yugo Gakkai-Shi, 72(2), p.163 - 165, 1996/02
no abstracts in English
Okazaki, Koki*; Naito, Susumu*; Nakayama, Kunihiko*; Makino, Shunichiro*; Shigeyama, Musashi*; Kuwako, Akira*; Izumi, Mikio*; Ito, Jun*; Okada, Hisashi*; Muto, Keitaro
no journal, ,
In fast breeder reactor (FBR), it is important to detect a small sodium leak surely for safety. As the coolant sodium used in FBR is low pressure, a small leak occurs from a crack before a pipe breaks, therefore it is possible to detect a sodium leak so as to shutdown a reactor before a pipe completely breaks. The sodium leaking from piping of cooling system reacts with oxygen etc. including with the ambient gas to form aerosols. In the second coolant system of the prototype liquid metal FBR Monju, the ambient air around piping is drawn into radiative ionization detector (RID). When sodium aerosols are detected by RID, chemical analysis of aerosols and the viewing of the leak point are carried out, then sodium leak is confirmed. As the signal of RID depends on temperature strongly and RID detects the aerosols which do not include sodium, the improvements of RID are demanded for reliability. Moving fluid ionization detector (MID) and laser leak detector (LLD) have been developed to improve these points. MID can reduce the dependence for temperature of the signal strength, and LLD can detect sodium atoms which are included in aerosols by means of laser-induced breakdown spectroscopy. An experiment was carried out for validating sodium leak detection system with MID and LLD under real environment installed in the second coolant system of Monju. In the experiments, sodium was not leaked, and ambient air around piping of the secondary coolant system was introduced through actual sampling line and measured by MID and LLD. In addition a sodium level in the ambient air was measured by means of ion chromatography. The experiment showed that the background signals of MID and LLD were stable and low and that the sodium level due to the background of salinity (NaCl) contained in the ambient air was lower than three orders of magnitude than the sodium level for small sodium leak. The plant applicability of MID and RID was validated by this experiment.
Oyama, Kenji*; Yokoo, Tetsuya*; Ito, Shinichi*; Suzuki, Junichi*; Iwasa, Kazuaki*; Sato, Taku*; Kira, Hiroshi*; Sakaguchi, Yoshifumi*; Ino, Takashi*; Oku, Takayuki; et al.
no journal, ,
Yoshida, Keisuke; Yamada, Katsunori; Yoda, Tomoyuki; Tsunoda, Junichi; Muto, Yasushi; Kobayashi, Makoto; Kikuchi, Masamitsu
no journal, ,
no abstracts in English
Kato, Shinya; Morohashi, Yuko; Muto, Keitaro
no journal, ,
In order to confirm performance of MONJU failed fuel detection and location system (FFDL), confirmation of accuracy for identifying failed fuel will be conducted by using simulated tag gas.
Kawabata, Mamoru; Sawa, Mamoru; Ono, Fumiyasu; Shimosaka, Mitsuo; Muto, Keitaro; Uchihashi, Masaya
no journal, ,
As a replacement for the analog camera system which has become difficult to repair, a digital transmission system using VDSL technology was devised by reusing idle facilities such as the voice communication network. This paper presents an overview of the remote monitoring system that can flexibly respond to the installation of additional cameras for other remote monitoring needs such as decommissioning work and equipment operation status checks that will increase in the future MONJU, as well as the transmission of measurement data from temporary instruments at a low cost.
