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Sasamoto, Hiroshi; Ishii, Tomoko*; Sato, Hisao*; Sazarashi, Masami
JAEA-Research 2010-030, 64 Pages, 2010/09
JAEA-Research-2010-030.pdf:15.41MB
It is necessary to evaluate the alteration behavior of buffer material by interactions of overpack (iron) and buffer (bentonite) materials for geological disposal of high level radioactive waste. In the present study, laboratory experiments were carried out for the better understanding of phenomena caused by iron-bentonite (smectite) interactions. Before conducting the experiments, literature survey was performed to summarize the existing knowledge about iron-bentonite interactions and to identify the dominant factors affecting the alteration behavior. As the results of experiment, experimental conditions caused remarkable alteration, secondary minerals suggested as alteration product, different behavior of alteration between batch and compacted systems etc. were revealed.
Suzuki, Sadaaki; Seki, Masami; Shinozaki, Shinichi; Sato, Fumiaki; Hiranai, Shinichi; Ishii, Kazuhiro*; Hasegawa, Koichi; Moriyama, Shinichi
JAEA-Technology 2007-055, 27 Pages, 2007/09
JAEA-Technology-2007-055.pdf:4.18MB
In the experiments featuring lower hybrid range of frequency (LHRF) system in JT-60U, carbon grills were attached to the plasma-facing part of the antenna in order to avoid the damage by the excessive heat load from the plasma. However some electric discharge traces were found there in the observation after the experiments. To avoid such discharges, improvements of the arc detector and the protection interlock by visible picture detection were tackled. In the arc detector, the amplification circuit was improved in order to obtain shorter response time and higher resolution of optical detection. Moreover, in visible picture detection, a new function of RF-on/off control utilizing PC image processing was added to distinguish the light of the arc from one of the plasma. This report summarizes improvement of the protection interlock device in a LHRF heating system.
Ishii, Kazuhiro; Seki, Masami; Shinozaki, Shinichi; Hasegawa, Koichi; Hiranai, Shinichi; Suzuki, Sadaaki; Sato, Fumiaki; Moriyama, Shinichi; Yokokura, Kenji
JAEA-Technology 2007-036, 30 Pages, 2007/07
JAEA-Technology-2007-036.pdf:17.06MB
The lower hybrid (LH) antenna in JT-60U has interaction with plasmas because it should be close to them in order to inject effectively radio frequency (RF) power into them. As a result, it has been a serious problem that the antenna mouth made of stainless steels was damaged due to excessive heat loads of plasmas and RF breakdowns. To solve the problem, a heat-resistant LH antenna was developed tipping carbon grills with fairly high heat resistance on the antenna mouth, and therefore reduction in damages on the mouth was expected. Power injection into plasmas was firstly performed with the heat-resistant antenna. RF conditioning was done carefully in the initial phase because RF breakdown due to outgassing from the grills might be occurred. After sufficient degassing was done through RF conditioning, RF power of about 1.6 MW 
10 sec injection was successfully injected to plasmas. Moreover it was demonstrated that it had comparably high plasma current drive capability (about 1.6 10
A/W/m
), required as a current drive LH antenna.
Takahashi, Masami*; Seki, Masami; Shimono, Mitsugu; Terakado, Masayuki; Igarashi, Koichi*; Ishii, Kazuhiro*; Kasugai, Atsushi
JAERI-Tech 2003-080, 27 Pages, 2003/11
JAERI-Tech-2003-080.pdf:3.11MB
The JT-60U electron cyclotron heating (ECH) system has been introduced to suppress MHD instabilities via a current profile control by local heating or current drive. The ECH system consists of four 1MW-110GHz gyrotrons, four 60m transmission lines composed of a corrugated waveguide with a diameter of 31.75mm and two steerable type mirror antennas. Recently, a gyrotron developed for ITER has realized high power in an extremely high frequency range of millimeter waves although there was no high power source around 110GHz ten years ago. Therefore, it requires many techniques to operate the gyrotoron. The oscillation conditions had to be found at output power 1MW by adjusting the magnetic field parameters and anode voltage after heater aging. Then conditioning of the gyrotoron was done, where the pulse length is gradually extended in order to operate for 1sec level of pulse length. Consequently, 1MW-5sec of the designed value was achieved and the ECH system with four gyrotrons successfully injected the millimeter wave energy of 10MJ into plasmas, which is the world record.
Ishii, Kazuhiro*; Seki, Masami; Shimono, Mitsugu; Terakado, Masayuki; Igarashi, Koichi*; Takahashi, Masami*
JAERI-Tech 2003-079, 22 Pages, 2003/10
JAERI-Tech-2003-079.pdf:3.01MB
In JT-60U, the study of current drive by radio-frequency (RF) waves in lower hybrid range of frequency (LHRF) has been done as one of research and development works aiming at steady state operation of tokamaks. The main subject of hardware and technology development in this study is to develop a high power LHRF antenna, the main component of the system. The LHRF antenna is set closely to plasma to efficiently inject RF power into it. The LHRF antenna normally receives heat loads from the plasma, and it is required to inject high RF power. Then, it has become a problem that the antenna mouth was melted by excessive heat loads from plasma or it was melted and deformed by RF discharges. As a counter measurement against this, the LHRF antenna has been conditioned to improve its stand-off voltage capability. Furthermore, by monitoring the temperature of the LHRF antenna, adjusting its position, developing a injection method of power modulation even for current drive, and setting an arc sensor which picks up the RF discharge, the damage of the antenna mouth has been suppressed.
Shimono, Mitsugu; Seki, Masami; Terakado, Masayuki; Igarashi, Koichi*; Ishii, Kazuhiro*; Takahashi, Masami*; Shinozaki, Shinichi; Hiranai, Shinichi; Sato, Fumiaki*; Anno, Katsuto
JAERI-Tech 2003-075, 29 Pages, 2003/09
JAERI-Tech-2003-075.pdf:4.62MB
no abstracts in English
Igarashi, Koichi*; Seki, Masami; Shimono, Mitsugu; Terakado, Masayuki; Ishii, Kazuhiro*; Takahashi, Masami*
JAERI-Tech 2003-030, 40 Pages, 2003/03
JAERI-Tech-2003-030.pdf:5.83MB
The JT-60U electron cyclotron heating (ECH) system can heat plasmas locally and drive a plasma current with four 1 MW-5 sec gyrotrons. The super conducting magnets (SCM) are required for oscillation of the gyrotron at a working frequency of 110 GHz. The SCM provides a high magnetic field of 4.5T at the cavity inside the gyrotron. This SCM system is characterized by (1) operation without liquid Helium owing to a 4 K-refrigerator applied to the magnetic coils, (2) easy maintenance. Operational experiences about the SCM system through a long term experiment for a high power gyrotron are very valuable. According to those operational experiences, it is clarified the 4 K-refrigerator should be renewed in oder to keep low temperature of the SCM. It is also found that 200 hours or less are required for the super conducting condition (
5K) after long stopping time of the refrigerator up to 150 hours. This is useful information for making a plan about ECH experiments.
Terakado, Masayuki; Shimono, Mitsugu; Igarashi, Koichi*; Takahashi, Masami*; Ishii, Kazuhiro*; Seki, Masami
Heisei-14-Nendo Tokyo Daigaku Sogo Gijutsu Kenkyukai Gijutsu Hokokushu, 3 Pages, 2003/03
no abstracts in English
Shimono, Mitsugu; Seki, Masami; Terakado, Masayuki; Igarashi, Koichi*; Ishii, Kazuhiro*; Kajiwara, Ken; Anno, Katsuto
NIFS-MEMO-36, p.382 - 385, 2002/06
no abstracts in English
Saito, Yuji; Suga, Shigemasa*; Kakizaki, A.*; Matsushita, T.*; Imada, S.*; Daimon, H.*; Ono, Kanta*; Fujisawa, M.*; Kinoshita, T.*; Ishii, T.*; et al.
Journal of Electron Spectroscopy and Related Phenomena, 78, p.329 - 332, 1996/05
Times Cited Count：0 Percentile：0.03(Spectroscopy)no abstracts in English
Ara, Katsuyuki; ; ; *; *
FAPIG, 0(125), p.19 - 27, 1990/07
no abstracts in English
Moriyama, Shinichi; Yokokura, Kenji; Hasegawa, Koichi; Suzuki, Sadaaki; Hiranai, Shinichi; Ishii, Kazuhiro; Sato, Fumiaki; Tani, Takashi; Igarashi, Koichi; Shimono, Mitsugu; et al.
no journal, ,
no abstracts in English
Seki, Masami; Sawahata, Masayuki; Shinozaki, Shinichi; Hiranai, Shinichi; Suzuki, Sadaaki; Hasegawa, Koichi; Shimono, Mitsugu; Yokokura, Kenji; Ishii, Kazuhiro; Sato, Fumiaki; et al.
no journal, ,
no abstracts in English
Suzuki, Sadaaki; Hasegawa, Koichi; Shinozaki, Shinichi; Sato, Fumiaki; Hiranai, Shinichi; Ishii, Kazuhiro; Seki, Masami; Moriyama, Shinichi; Yokokura, Kenji
no journal, ,
no abstracts in English
Moriyama, Shinichi; Fujii, Tsuneyuki; Seki, Masami; Sawahata, Masayuki; Suzuki, Sadaaki; Shinozaki, Shinichi; Terakado, Masayuki; Hiranai, Shinichi; Hasegawa, Koichi; Shimono, Mitsugu; et al.
no journal, ,
no abstracts in English
Sasamoto, Hiroshi; Sazarashi, Masami; Ishii, Tomoko*; Sato, Hisao*; Kato, Hiroyasu*
no journal, ,
To investigate bentonite-iron interaction under high temperature condition, alteration experiments considering several factors (smectite composition, solution chemistry, iron-bentonite ratio) which were believed to affect on bentonite alteration were conducted with different experimental conditions. As the results, it was suggested that the factors considered in this study could also significantly affect on bentonite alteration in addition to temperature condition.
Sasamoto, Hiroshi; Sazarashi, Masami; Ishii, Tomoko*; Sato, Hisao*; Kato, Hiroyasu*
no journal, ,
To investigate bentonite-iron interaction under high temperature condition, alteration experiments considering several factors (smectite composition, solution chemistry, iron-bentonite ratio) which were believed to affect on bentonite alteration were conducted with different experimental conditions. As the results, it was suggested that the factors considered in this study could also significantly affect on bentonite alteration in addition to temperature condition.
Sasamoto, Hiroshi; Sazarashi, Masami; Ishii, Tomoko*; Kato, Hiroyasu*; Sugiyama, Kazutoshi*
no journal, ,
Regarding to alteration of bentonite coexisting with iron material, laboratory experiments with different temperature and iron-bentonite (I/B) ratio and literature surveys for bentonite alteration in the natural system were conducted. As the results, the conditions which promote the alteration of smectite significantly were estimated approximately. Additionally, the important alteration products necessary for evaluation of smectite alteration were summarized by literature surveys. Such information will be useful for evaluation of smectite alteration considering the conditions of time and duration interested.
Ishii, Hiroto*; Oishi, Yuji*; Muta, Hiroaki*; Suzuki, Eriko; Nakajima, Kunihisa; Miwa, Shuhei; Osaka, Masahiko; Uno, Masayoshi*; Kurosaki, Ken*
no journal, ,
This study experimentally investigates the wettability of liquid cesium iodide on the stainless steel (SUS 316) solid surfaces by the sessile drop method. wettedly, and iodine compounds were revaporized by the oxidation of cesium iodide.
