Electronic structure in heavy fermion compound UPdAl through directional Compton profile measurement

Koizumi, Akihisa*; Kubo, Yasunori*; Yamamoto, Etsuji; Haga, Yoshinori; Sakurai, Yoshiharu*

Journal of the Physical Society of Japan, 88(3), p.034714_1 - 034714_6, 2019/03

https://doi.org/10.7566/JPSJ.88.034714

Catalyst technology of Tanaka Kikinzoku Kogyo

Kubo, Hitoshi*; Oshima, Yusuke*; Iwai, Yasunori

JETI, 63(10), p.33 - 36, 2015/09

Tanaka Kikinzoku Kogyo provides a broad range of precious metals products and technologies. Tanaka Kikinzoku Kogyo and Japan Atomic Energy Agency have jointly developed a new method of manufacturing catalysts involving hydrophobic processing with an inorganic substance base. As a result, previous technological issues were able to be solved with the development of a catalyst that exhibited no performance degradation in response to radiation application of 530 kGy, a standard for radiation resistance, and maintenance of thermal stability at over 600C, which is much higher than the 70C temperature that is normally used. The application of this catalyst to the liquid phase catalytic exchange process is expected to overcome significant technological hurdles with regards to improving the reliability and efficiency of systems for collecting tritium from tritiated water. It is also anticipated that the hydrophobic platinum catalyst manufacturing technology used for this catalyst could be applied to a wide range of fields other than nuclear fusion research. It was verified that if applied to a hydro oxidation catalyst, hydrogen could be efficiently oxidized, even at room temperature. This catalyst can also contribute to improving safety at non-nuclear plants that use hydrogen in general by solving the aforementioned vulnerability issue.

Successful development of a new catalyst for efficiently collecting tritium; A Breakthrough toward realization of fusion reactors

Iwai, Yasunori; Kubo, Hitoshi*; Oshima, Yusuke*

Kagaku, 70(5), p.35 - 40, 2015/05

We have successfully developed a new hydrophobic platinum catalyst for collecting tritium at nuclear fusion reactors. Catalysts used to collect tritium are called hydrophobic precious metal catalysts. In Japan, hydrophobic precious metal catalysts manufactured from polymers have been used for heavy water refinement. However, this catalyst has issues related to embrittlement to radiation and thermal stability. These technological issues needed to be solved to allow for its application to nuclear fusion reactors requiring further enrichment from highly-concentrated tritiated water. We developed a new method of manufacturing catalysts involving hydrophobic processing with an inorganic substance base. As a result, previous technological issues were able to be solved with the development of a catalyst that exhibited no performance degradation in response to radiation application of 530 kGy, a standard for radiation resistance, and maintenance of thermal stability at over 600C, which is much higher than the 70C temperature that is normally used. The catalyst created with this method was also confirmed to have achieved the world's highest exchange efficiency, equivalent to 1.3 times the previously most powerful efficiency. The application of this catalyst to the liquid phase catalytic exchange process is expected to overcome significant technological hurdles with regards to improving the reliability and efficiency of systems for collecting tritium from tritiated water.

Hydrophobic Pt catalyst for combustion of hydrogen isotopes at low temperatures

Iwai, Yasunori; Kubo, Hitoshi*; Sato, Katsumi; Oshima, Yusuke*; Noguchi, Hiroshi*; Taniuchi, Junichi*

Proceedings of 7th Tokyo Conference on Advanced Catalytic Science and Technology (TOCAT-7) (USB Flash Drive), 2 Pages, 2014/06

Hydrophobic platinum catalysts have been developed especially for combustion of hydrogen isotopes released in a nuclear facility. A new type of hydrophobic hydrogen combustion catalyst commercially named TKK-KNOITS catalyst is hardly susceptible to water mist and water vapor in the atmosphere and water produced by hydrogen combustion. It is capable of maintaining the activity even at relatively low temperatures. The TKK-KNOITS catalyst is superior to other previous hydrophobic catalysts in applicability to wide range of hydrogen concentration from very thin to dense. The catalyst which carrier is composed of inorganic oxide has thermal stability up to 873 K.

Room-temperature reactor packed with hydrophobic catalysts for the oxidation of hydrogen isotopes released in a nuclear facility

Iwai, Yasunori; Sato, Katsumi; Taniuchi, Junichi*; Noguchi, Hiroshi*; Kubo, Hitoshi*; Harada, Nobuo*; Oshima, Yusuke*; Yamanishi, Toshihiko

Journal of Nuclear Science and Technology, 48(8), p.1184 - 1192, 2011/08

https://doi.org/10.3327/jnst.48.1184

The inorganic-based hydrophobic Pt-catalyst named H1P has been developed especially for efficient oxidation of a tracer level of tritium in the ambient temperature range even in the presence of saturated water vapor. The overall reaction rate constant for H1P catalyst in the ambient temperature range was considerably larger than that for traditionally applied Pt/AlO catalyst. Moreover, the decrease in reaction rate for H1P in the presence of saturated water vapor compared with in the absence of water vapor was slight due to its excellence in hydrophobic performance. Oxidation reaction on the catalyst surface is the rate-controlling step in the ambient temperature range and diffusion in a catalyst substratum above 313 K due to its fine porosity. The overall reaction rate constant in the ambient temperature range was dependent on the space velocity and hydrogen concentration in carrier.

Heavy fermion state in YbIrZn

Yoshiuchi, Shingo*; Toda, Masatoshi*; Matsushita, Masaki*; Yasui, Shinichi*; Hirose, Yusuke*; Oya, Masahiro*; Katayama, Keisuke*; Honda, Fuminori*; Sugiyama, Kiyohiro*; Hagiwara, Masayuki*; et al.

Journal of the Physical Society of Japan, 78(12), p.123711_1 - 123711_4, 2009/12

https://doi.org/10.1143/JPSJ.78.123711

Characteristics of runaway plasmas in JT-60U

Kawano, Yasunori; Nakano, Tomohide; Isayama, Akihiko; Hatae, Takaki; Konoshima, Shigeru; Oyama, Naoyuki; Kondoh, Takashi; Tamai, Hiroshi; Kubo, Hirotaka; Asakura, Nobuyuki; et al.

Europhysics Conference Abstracts (CD-ROM), 29C, 4 Pages, 2005/00

http://epsppd.epfl.ch/Tarragona/pdf/P2_068.pdf

In order to mitigate the post-disruption runaway electrons, experiments has been carried out with impurity pellet injection. As a result, we have observed the prompt exhaust of the runaway electrons and the reduction of runaway plasma. We have presented one possible explanation for basic behavior of the runaway plasma current that it follows the balance of the avalanche generation of runaway electrons and their slowing down predicted by the model, including effects by synchrotron radiation. On the other hand, standing on the fact that the current quench time is extended by runaway electrons, the experiment for avoiding the current quench by runaway electrons has been carried out. The runaway electrons reinforced the discharge to survive against the low Te of less than several tens eV and an additional impurity pellet injection, and thus the plasma current was maintained and terminated as programmed. To study the dynamics of runaway electrons precisely, a new active and direct diagnostic concept using the laser inverse Compton scattering has been proposed.

Fusion plasma performance and confinement studies on JT-60 and JT-60U

Kamada, Yutaka; Fujita, Takaaki; Ishida, Shinichi; Kikuchi, Mitsuru; Ide, Shunsuke; Takizuka, Tomonori; Shirai, Hiroshi; Koide, Yoshihiko; Fukuda, Takeshi; Hosogane, Nobuyuki; et al.

Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.185 - 254, 2002/09

https://doi.org/10.13182/FST02-A227

With the main aim of providing physics basis for ITER and the steady-state tokamak reactors, JT-60/JT-60U has been developing and optimizing the operational concepts, and extending the discharge regimes toward sustainment of high integrated performance in the reactor relevant parameter regime. In addition to achievement of the equivalent break-even condition (QDTeq up to 1.25) and a high fusion triple product = 1.5E21 m-3skeV, JT-60U has demonstrated the integrated performance of high confinement, high beta-N, full non-inductive current drive with a large fraction of bootstrap current in the reversed magnetic shear and in the high-beta-p ELMy H mode plasmas characterized by both internal and edge transport barriers. The key factors in optimizing these plasmas are profile and shape controls. As represented by discovery of various Internal Transport Barriers, JT-60/JT-60U has been emphasizing freedom and restriction of profiles in various confinement modes. JT-60U has demonstrated applicability of these high confinement modes to ITER and also clarified remaining issues.

Steady state high performance in JT-60U

Kamada, Yutaka; Ushigusa, Kenkichi; Neyatani, Yuzuru; Naito, Osamu; Ozeki, Takahisa; Kawano, Yasunori; Yoshino, Ryuji; Kubo, Hirotaka; Fujita, Takaaki; Ishida, Shinichi; et al.

IAEA-CN-60/A5-5, 0, p.651 - 661, 1995/00

no abstracts in English

Performance of the JT-60 ICRF antenna with an open type Faraday shield

Fujii, Tsuneyuki; Saigusa, Mikio; Kimura, Haruyuki; Moriyama, Shinichi; ; Kawano, Yasunori; *; Kubo, Hirotaka; Nishitani, Takeo; *; et al.

Fusion Engineering and Design, 19, p.213 - 223, 1992/00

https://doi.org/10.1016/0920-3796(92)90031-X

no abstracts in English