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Iwai, Yasunori; Yamanishi, Toshihiko; Isobe, Kanetsugu; Nishi, Masataka; Yagi, Toshiaki; Tamada, Masao
Fusion Engineering and Design, 81(1-7), p.815 - 820, 2006/02
Times Cited Count：15 Percentile：70.56(Nuclear Science & Technology)Solid-polymer-electrolyte (SPE) water electrolysis is attractive in electrolytic process of water detritiation system (WDS) in fusion reactors because it can electrolyze liquid waste directly, but radioactive durability of its ion exchange membrane is a key point. Radioactive durability of Nafion, a typical commercial ion exchange membrane, was experimentally investigated using Co-60 irradiation facility and electron beam irradiation facility at Takasaki Radiation Chemistry Research Establishment of JAERI. Nafion is composed of PTFE (Polytetrafluoroethylene) main chain. However the degradation of its mechanical strength by irradiation was significantly distinguished from that of PTFE and no serious damage was observed for its ion exchange capacity up to 530 kGy, the requirement of ITER. Atmospheric effects such as soaking and oxygen on degrading behaviors were discussed from the viewpoint of radical reaction mechanism. Dependencies of operating temperature and radioactive source are also demonstrated in detail.
Iwai, Yasunori; Yamanishi, Toshihiko; Nishi, Masataka; Yagi, Toshiaki; Tamada, Masao
Journal of Nuclear Science and Technology, 42(7), p.636 - 642, 2005/07
Times Cited Count：20 Percentile：77.57(Nuclear Science & Technology)Radioactive durability of organic polymers in solid-polymer-electrolyte water electrolyzer was investigated by 
-ray irradiation. Serious deteriorations for tensile strength and ion exchange capacity of ion exchange membrane (Nafion) were not observed up to 850 kGy. No serious damage was also observed for the gasket materials (Aflas) up to 500 kGy. PFA and FEP, insulator materials, lost their tensile strength at 300 kGy or less. As the result, it is concluded that the electrolyzer could be used up to around 500 kGy in the case where PFA and FEP are replaced by the polyimide resin whose durability is well demonstrated. Two degrading mechanisms were supposed. One is direct degradation by energy of radial rays. The other is that by the attack of radicals. It was demonstrated that the effect of radicals on the membrane was not dominant. The quantity of dissolved fluorine in water was found to correlate with the tensile strength and ion exchange capacity. Hence, it is possible to evaluate the degradation of the membrane by monitoring the quantity of dissolved fluorine.
Yamaki, Tetsuya; Asano, Masaharu; Yoshida, Masaru
Gekkan Eko Indasutori, 10(6), p.5 - 11, 2005/06
no abstracts in English
Yamaki, Tetsuya; Asano, Masaharu; Yoshida, Masaru
Kogyo Zairyo, 53(1), p.63 - 67, 2005/01
no abstracts in English
Yamaki, Tetsuya; Yoshida, Masaru
Nenryo Denchi, 4(3), p.73 - 78, 2005/01
no abstracts in English
Yamaki, Tetsuya; Asano, Masaharu; Maekawa, Yasunari; Morita, Yosuke; Suwa, Takeshi; Chen, J.*; Tsubokawa, Norio*; Kobayashi, Kazuhiro*; Kubota, Hitoshi*; Yoshida, Masaru
Radiation Physics and Chemistry, 67(3-4), p.403 - 407, 2003/08
Times Cited Count：76 Percentile：97.02(Chemistry, Physical)no abstracts in English
Yamaki, Tetsuya; Asano, Masaharu; Yoshida, Masaru
Kogyo Zairyo, 51(4), p.39 - 42, 2003/04
no abstracts in English
Inoue, Yutaka; Kobayashi, Kazuhiro; Yamaki, Tetsuya; Asano, Masaharu; Kubota, Hitoshi*; Yoshida, Masaru
Dai-2-Kai 21-Seiki Rengo Shimpojiumu; Kagaku Gijutsu To Ningen Rombunshu, p.257 - 260, 2003/00
We prepared crosslinked fluoropolymer electrolyte membranes for use in fuel cells and then investigated their structural properties by X-ray diffraction (XRD) analysis. The radiation-induced grafting of styrene into crosslinked polytetrafluoroethylene (PTFE) films and subsequent sulfonation enabled us to obtain the electrolyte membrane with a sufficient ion exchange capacity, which exceeds that of the commercially-available film, Nafion. As the crosslinking and styrene grafting reactions proceeded, the size of the PTFE crystallites in the film became smaller, thereby decreasing the film crystallinity. Interestingly, in contrast to Nafion, the resulting sulfonated membranes were found to have high crystallinity.
Yamaki, Tetsuya; Asano, Masaharu; Morita, Yosuke*; Suwa, Takeshi*; Yoshida, Masaru
Proceedings of 9th International Conference on Radiation Curing (RadTech Asia '03) (CD-ROM), 4 Pages, 2003/00
Proton exchange membranes were prepared by the radiation-induced grafting of styrene into crosslinked polytetrafluoroethylene (PTFE) films and subsequent sulfonation. The degree of grafting was controlled in the range of 7-75% by the crosslinking density of the PTFE matrix as well as the grafting conditions. The films at the grafting yield of 
30% were found to give the ion exchange membranes with a homogeneous distribution of sulfonic acid groups. The resulting membranes showed a large ion exchange capacity reaching 2.9 meq g
, which exceeded the performance of commercially-available perfluorosulfonic acid films such as Nafion. This will encourage the use of our ion exchange membranes in polymer electrolyte fuel cells.
Yoshida, Masaru; Yamaki, Tetsuya
Saishin Nenryo Denchi Buzai; Sono Saisentan Gijutsu To Shinraisei Hyoka, p.82 - 92, 2003/00
no abstracts in English
Yamaki, Tetsuya; Yoshida, Masaru
Zukai, Nenryo Denchi no Subete, p.117 - 119, 2003/00
no abstracts in English
Onuki, Toshihiko
Radiochimica Acta, 64, p.237 - 245, 1994/00
no abstracts in English
Goto, Mitsuaki*; Yamaki, Tetsuya; Koshikawa, Hiroshi; Sawada, Shinichi; Kitamura, Akane; Higa, Mitsuru*
no journal, ,
We have exploited a grafting technique with heavy-ion beams to create ion exchange membranes for various practical applications such as fuel cells and water desalination systems. In this study, instead of styrene that is a common monomer, sodium styrene sulfonate (SSS) was for the first time employed for this so-called ion-track grafting. A 25 
m-thick poly(vinylidene fluoride) film was bombarded with 560 MeV 
Xe at a fluence of 3.0
10
or 1.010
ions/cm
, and subsequently immersed in a SSS grafting solution at 60
C. The charge density was estimated through the measurement of the membrane potential in an aqueous solution of potassium chloride. Our membranes exhibited higher charge density than the conventional or commercially-available samples probably due to track structures characteristic of the bombarding heavy ions.
Sato, Junya; Sakakibara, Tetsuro; Meguro, Yoshihiro; Nakazawa, Osamu
no journal, ,
no abstracts in English
Saito, Tatsuo
no journal, ,
In order to evaluate the amount of uranium, which is a major radionuclide in the safety assessment of disposal of wastes from research, medical and RI using facilities, we are developing a model to evaluate the migration behavior of uranium in consideration of environmental conditions. In this study, in order to evaluate the applicability of the developed model to the actual environment, the uranium concentration in the river was evaluated from the uranium concentration in the soil around the river in Japan and was compared with the measured value.
