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Iwai, Yasunori; Kubo, Hitoshi*; Oshima, Yusuke*
Isotope News, (736), p.12 - 17, 2015/08
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
C, 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.
Aso, Tomokazu; Tatsumoto, Hideki; Hasegawa, Shoichi; Ushijima, Isamu*; Otsu, Kiichi*; Kato, Takashi; Ikeda, Yujiro
AIP Conference Proceedings 823, p.763 - 770, 2006/05
no abstracts in English
Kinoshita, Hidetaka; Haga, Katsuhiro; Kogawa, Hiroyuki; Kaminaga, Masanori; Hino, Ryutaro
Proceedings of ICANS-XVI, Volume 3, p.1305 - 1314, 2003/07
The JAERI and the KEK are promoting a plan to construct the spallation neutron source at the Tokai Research Establishment, JAERI, under J-PARC project. A mercury circulation system has been designed so as to supply mercury to the target stably. Conceptual design is almost finished. But, it was necessary to confirm a mercury pump performance, and more, to investigate erosion rate under the mercury flow as well as an amount of mercury remained on the surface after drain. The mercury pump performance was tested under the mercury flow conditions by using an experimental gear pump, which had almost the same structure as a practical mercury pump to be expected, and the erosion rates in a mercury pipeline as were investigated. The discharged flow rates of the gear pump increased linearly with the rotation speed. Erosion rates obtained under the mercury velocity less than 1.6 m/s was found to be so small. For the amount of remaining mercury on the pipeline, radioactivity of this remaining mercury volume was found to be three-order lower than that of the target casing.
/He mixed gas under room temperatureTanzawa, Sadamitsu; Hiroki, Seiji; Abe, Tetsuya
Shinku, 46(3), p.154 - 157, 2003/03
no abstracts in English
Iwai, Yasunori; Yamanishi, Toshihiko; Ohira, Shigeru; Suzuki, Takumi; Shu, Wataru; Nishi, Masataka
Fusion Engineering and Design, 61-62, p.553 - 560, 2002/11
Times Cited Count：15 Percentile：65.5(Nuclear Science & Technology)no abstracts in English
Iwai, Yasunori; Nakamura, Hirofumi; Konishi, Satoshi; Nishi, Masataka; Willms, R. S.*
Fusion Science and Technology, 41(3), p.668 - 672, 2002/05
no abstracts in English
Iwai, Yasunori; Yamanishi, Toshihiko; Nishi, Masataka
Fusion Technology, 39(2-Part2), p.1078 - 1082, 2001/03
no abstracts in English
Aso, Tomokazu; Teshigawara, Makoto; Hasegawa, Shoichi; Muto, Hideki*; Aoyagi, Katsuhiro*; Takada, Hiroshi; Ikeda, Yujiro
no journal, ,
no abstracts in English
Aso, Tomokazu; Teshigawara, Makoto; Hasegawa, Shoichi; Muto, Hideki*; Aoyagi, Katsuhiro*; Takada, Hiroshi; Ikeda, Yujiro
no journal, ,
no abstracts in English
Teshigawara, Makoto; Aso, Tomokazu; Hasegawa, Shoichi; Muto, Hideki*; Aoyagi, Katsuhiro*; Takada, Hiroshi; Ikeda, Yujiro
no journal, ,
Performance degradation of helium refrigerator was occurred for liquid hydrogen circulation system of J-PARC high intensity neutron source since 2015. In order to find the cause of performance degradation of helium refrigerator, we investigated the impurities in helium gas and accumulated oil in inside cold box components by quadrupole mass spectrometer and organic solvent extraction. The measured impurities and accumulated oil were less than design value. We collected 143g of total amount of accumulated oil from heat exchanger and adosorber, which was corresponded to estimated value from 10 ppb of oil contamination in helium and accumulated operation period. However, we only could find out that accumulated oil like coating film on top surface of felt, which was used to hold the active charcoal in adsorber. We report detailed measurement results of impurities, accumulated oil, etc., to find the cause of performance degradation.
Teshigawara, Makoto; Aso, Tomokazu; Muto, Hideki*; Aoyagi, Katsuhiro*; Takada, Hiroshi; Ikeda, Yujiro
no journal, ,
Performance degradation of helium refrigerator was occurred for liquid hydrogen circulation system of J-PARC high intensity neutron source since 2015. During cause investigation of performance degradation of helium refrigerator, we found out that accumulated oil like coating film on top surface of felt, which was used to hold the active charcoal in adsorber, might cause pressure difference in adsorber. We performed cold nitrogen gas flow test in the felt accumulated oil and found out that frozen oil under cold nitrogen flow caused the pressure difference.
Aso, Tomokazu; Teshigawara, Makoto; Muto, Hideki*; Aoyagi, Katsuhiro*; Takada, Hiroshi
no journal, ,
Liquid hydrogen (20 K, 1.4 MPaG) is employed as a cold neutron moderator material at the 1 MW spallation neutron source of Japan Proton Accelerator Research Complex (J-PARC). The cryogenic hydrogen system, combined with a helium refrigerator, was adopted to generate a liquid hydrogen circulation flow (185 g/s). Since January 2015, a pressure drop gradually increased between heat exchangers HXs) and an adsorber (ADS) in the helium refrigerator for each operation, causing the refrigerator performance degradation. The performance of helium refrigerator could be recovered as a result of countermeasures focused on accumulated oil removal, such as cleaning the inside HXs and exchanging the ADS at 2016 summer shutdown, however the detailed cause is still in doubt. On the other hand, a long run stable operation could be secured over 175 days in 2018. Just end of long run operation, a first high-intensity-beam injection with 1MW beam power was also carried out for one hour aiming to confirm the refrigerator performance according to design requirement.
