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Journal Articles

Development of hydrophobic platinum catalyst for the effective collection of tritium in fusion plants

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

Isotope News, (736), p.12 - 17, 2015/08

http://www.jrias.or.jp/books/pdf/201508_TENBO_IWAI.pdf

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 530kGy, a standard for radiation resistance, and maintenance of thermal stability at over 600 $^{circ}$ C, which is much higher than the 70 $^{circ}$ C 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.

Journal Articles

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 600 $^{circ}$ C, which is much higher than the 70 $^{circ}$ C 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.

JAEA Reports

Production and installation of equipments for radiation-induced graft polymerization in liquid phase and dipping techniques

Seko, Noriaki; Takeda, Hayato*; Kasai, Noboru; Tamada, Masao; Hasegawa, Shin; Katakai, Akio; Sugo, Takanobu*

JAERI-Tech 2004-075, 51 Pages, 2005/01

JAERI-Tech-2004-075.pdf:8.0MB

Fibrous adsorbent which is synthesized by radiation induced graft polymerization on the trunk polymers such as polymer nonwoven fabrics and woven cloths exhibits an excellent selective adsorption against heavy metal ions and toxic gases at extremely low concentrations. Two equipments were installed to synthesize the metal-ion and gas adsorbents by means of the radiation-induced graft polymerization in the liquid phase and the dipping, respectively. In the reaction chamber of the liquid phase reactor, the oxygen decreased to 100ppm. The inside temperature raised to 80 $^{circ}$ C. These characteristics satisfied the specification. The fabric transport can regulate the rate in the range from 1 to 10m/min. The reactor for the dip grafting could reduce the inside oxygen to 100ppm and inside temperature could reach to 80 $^{circ}$ C. The grafting of GMA was carried out as a characteristic test. The degree of grafting was controlled in the range from 40 to 70%.

Journal Articles

Determination of low-pressure crystalline-liquid phase boundary of SnI $_{4}$

Fuchizaki, Kazuhiro*; Fujii, Yasuhiko*; Oishi, Yasuo*; Omura, Ayako*; Hamaya, Nozomu*; Katayama, Yoshinori; Okada, Taku

Journal of Chemical Physics, 120(23), p.11196 - 11199, 2004/06

https://doi.org/10.1063/1.1751397

Times Cited Count：24 Percentile：60.17(Chemistry, Physical)

The location of the liquidus in the low-pressure crystalline phase of SnI $_{4}$ was determined utilizing X-ray diffraction measurements under pressures up to approximately GPa. The liquidus is not well fitted to a monotonically increasing curve such as Simon's equation, but breaks near GPa and then becomes almost flat. The results are compared to those from molecular dynamics simulations. Ways to improve the model potential adopted in the simulations are discussed.

Journal Articles

Study on effect of effective thermal conductivities on melting characteristics of latent heat storage capsules

Shiina, Yasuaki; Inagaki, Terumi*

Nihon Kikai Gakkai Rombunshu, B, 69(681), p.1233 - 1241, 2003/05

https://doi.org/10.1299/kikaib.69.1233

In order to reduce phase change time in latent heat technology, improvement of effective thermal conductivity of heat storage unit would be one of the techniques. Effect of effective thermal conductivity on melting time are studied analytically of circular composite heat storage capsules made by immersing phase change materials (PCM) into porous metals. Numerical and approximate analysis were made with the consideration of uniform and non-uniform heat transfer coefficients around the cylindrical surface. Four PCMs (H $_{2}$ O,Octadecane, Li $_{2}$ CO $_{3}$ , NaCl) and three metals (copper, aluminum and carbon steel) were selected specific materials. Porosity of the metals were restricted larger than 0.9 in order to lessen decrease in latent heat. Results show that reduction in melting time was obtained for the above PCMs, especially for low conductivity PCMs. Melting time obtained by approximate analysis agrees well with numerical analysis. High Nusselt number and high thermal conductivity of heat transfer fluid would be more effective to reduce phase change time.