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Sawaguchi, Takuma; Takai, Shizuka; Sasagawa, Tsuyoshi; Uchikoshi, Emiko*; Shima, Yosuke*; Takeda, Seiji
MRS Advances (Internet), 8(6), p.243 - 249, 2023/06
In the intermediate depth disposal of relatively high-level radioactive waste, a method to confirm whether the borehole for monitoring is properly sealed should be developed in advance. In this study, groundwater flow analyses were performed for the hydrogeological structures with backfilled boreholes, assuming sedimentary rock area, to understand what backfill design conditions could prevent significant water pathways in the borehole, and to identify the confirmation points of borehole sealing. The results indicated the conditions to prevent water pathways in the borehole and BDZ (Borehole Disturbed Zone), such as designing the permeability of bentonite material less than or equal to that of the host rock, and grouting BDZ.
Ebihara, Kenichi; Sugiyama, Yuri*; Matsumoto, Ryosuke*; Takai, Kenichi*; Suzudo, Tomoaki
Metallurgical and Materials Transactions A, 52(1), p.257 - 269, 2021/01
Times Cited Count：14 Percentile：48.54(Materials Science, Multidisciplinary)We simulated the thermal desorption spectra of a small-size iron specimen to which was applied during charging with hydrogen atoms using a model incorporating the behavior of vacancies and vacancy clusters. The model considered up to vacancy clusters 
, which is composed of nine vacancies and employed the parameters based on atomistic calculations, including the H trapping energy of vacancies and vacancy clusters that we estimated using the molecular static calculation. As a result, we revealed that the model could, on the whole, reproduced the experimental spectra except two characteristic differences, and also the dependence of the spectra on the aging temperature. By examining the cause of the differences, the possibilities that the diffusion of clusters of 
and 
is slower than the model and that vacancy clusters are generated by applying strain and H charging concurrently were indicated.
-axis in -axis oriented YBCO thin filmsSueyoshi, Tetsuro*; Iwanaga, Yasuya*; Fujiyoshi, Takanori*; Takai, Yosuke*; Muta, Mitsuhiro*; Mukaida, Masashi*; Ichinose, Ataru*; Ishikawa, Norito
IEEE Transactions on Applied Superconductivity, 29(5), p.8003204_1 - 8003204_4, 2019/08
Times Cited Count：8 Percentile：37.35(Engineering, Electrical & Electronic)Columnar defects (CDs) along -axis were installed into an in-plane aligned -axis-oriented YBa
Cu
O
film by using heavy-ion irradiation, in order to clarify the influence of CDs on flux pinning properties around B
. The critical current density 
at B
significantly decreases after the irradiation, since the CDs act as a channel for flux creep along their length. The magnetic field dependence of at B, on the other hand, is weakened by the introduction of CDs.
in GdBCO-coated conductors with crossed columnar defects around planeSueyoshi, Tetsuro*; Iwanaga, Yasuya*; Fujiyoshi, Takanori*; Takai, Yosuke*; Mukaida, Masashi*; Kudo, Masaki*; Yasuda, Kazuhiro*; Ishikawa, Norito
IEEE Transactions on Applied Superconductivity, 27(4), p.8001305_1 - 8001305_5, 2017/06
Times Cited Count：9 Percentile：40.25(Engineering, Electrical & Electronic)We investigated in detail the flux pinning properties around B for GdBCO coated conductors with crossed columnar defects produced by heavy-ion irradiation, where the crossing angle was systematically controlled in the range from 5 to 15 relative to the ab-plane. A single peak of critical current density centered at B occurs for the crossing angle of 5, where an upward shift in can be observed compared to an unirradiated sample. As the crossing angle is larger, the peak becomes smaller and broader while maintaining the peak at B . Three peaks emerges at B and at the two irradiation angles, independently from the others.
Hwang, J.-G.*; Kim, E.-S.*; Miyajima, Tsukasa*; Honda, Yosuke*; Harada, Kentaro*; Shimada, Miho*; Takai, Ryota*; Kume, Tatsuya*; Nagahashi, Shinya*; Obina, Takashi*; et al.
Nuclear Instruments and Methods in Physics Research A, 753, p.97 - 104, 2014/07
Times Cited Count：7 Percentile：43.54(Instruments & Instrumentation)Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05
Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.
-ray preirradiation methodKimura, Yosuke; Asano, Masaharu; Chen, J.; Maekawa, Yasunari; Katakai, Ryoichi*; Yoshida, Masaru
Radiation Physics and Chemistry, 77(7), p.864 - 870, 2008/07
Times Cited Count：33 Percentile：86.11(Chemistry, Physical)We prepared polymer electrolyte membranes (PEMs) by post-polymerization of styrene (St) with divinylbenzene (DVB) into poly(ethylene-co-tetrafluoroethylene) (ETFE) films in the presence of toluene, isopropyl alcohol (iPrOH), tetrahydrofuran (THF), and tetrachloroethane (TCE) after pre--irradiation followed by a sulfonation. In the case of iPrOH, the grafting yield showed a marked increase compared with those of other solvents. On the other hand, it was found that the durability time of a PEM prepared in the presence of tetrachloroethane was 2 times higher than that in the presence of toluene.
Kimura, Yosuke*; Chen, J.; Asano, Masaharu; Maekawa, Yasunari; Katakai, Ryoichi*; Yoshida, Masaru
Nuclear Instruments and Methods in Physics Research B, 263(2), p.463 - 467, 2007/10
Times Cited Count：18 Percentile：72.92(Instruments & Instrumentation)Poly(ethylene-co-tetrafluoroethylene) (ETFE) films were irradiated by swift heavy ion-beams, followed by pre-irradiation for radiation grafting of styrene onto the ETFE films and sulfonation of the grafted ETFE films to prepare highly anisotropic proton-conducting membranes. The fluence of Xe ions and the addition of water in the grafting solvent were examined to determine their effect on the proton conductivity of the resultant membranes. It was found that the polymer electrolyte membrane prepared by grafting the styrene monomer in a mixture of isopropanol and water to the ETFE film with a ion-beam irradiation fluence was a highly anisotropic proton-conducting material, as the proton conductivity was 3 or more times higher in the thickness direction than in the surface direction of the membrane.
Hiroki, Akihiro; Maekawa, Yasunari; Katakai, Ryoichi*; Yamashita, Takashi*; Muroya, Yusa*; Katsumura, Yosuke*; Yoshida, Masaru
Macromolecules, 39(12), p.4132 - 4137, 2006/06
Times Cited Count：5 Percentile：16.00(Polymer Science)Hydrogels, which were synthesized by radiation-induced polymerization and cross-linked reactions of acryloyl-L-proline methyl ester at 0
C in aqueous alcohol solutions, exhibit ultraslow volume change in response to variations in external temperature. The shrinking speed of the hydrogels prepared in aqueous alcohol is 1000 times slower than that of the hydrogel prepared in pure water; e.g., the hydrogel prepared in aqueous 1-propanol at 0C shrank in 6 months. It is revealed that the ultraslow thermo-response consists of quick-shrinking and slow-shrinking periods; the ratio between the duration of the two periods depends on the alcohol molecules in the solution. The generation of hydroxyl group at the side chain of the polymer by the coupling reaction between 
-hydroxyalkyl radicals of alcohols and -radical of proline moiety was confirmed by GC/MS analysis of the radiation products. The hydrogen bonding domain containing the hydroxyl groups is proposed to be responsible for the ultraslow response.
Ebihara, Kenichi; Sugiyama, Yuri*; Takai, Kenichi*; Matsumoto, Ryosuke*; Suzudo, Tomoaki
no journal, ,
no abstracts in English
-induced grafting methods of styrene onto Xe ion irradiated poly(ethylene-co-tetrafluoroethylene)Kimura, Yosuke*; Yamamoto, Toshinori*; Kuroda, Shinichi*; Katakai, Ryoichi*; Kubota, Hitoshi*; Chen, J.; Asano, Masaharu; Maekawa, Yasunari; Yoshida, Masaru
no journal, ,
Polymer electrolyte fuel cell membranes based on poly(ethylene-co-tetrafluororthylene) (iETFE) irradiated with Xe ions as a function of fluence were prepared by UV- and -grafting methods. In the case of -grafting method, both the degree of grafting and the ion exchange capacity showed a higher value compared with UV-grafting method. It was able to be presumed from the results of water uptake that the change in dimension of the membrane obtained by -grafting method is controlled compared with that of UV-grafting method.
Kimura, Yosuke*; Katakai, Ryoichi*; Asano, Masaharu; Chen, J.; Maekawa, Yasunari; Yoshida, Masaru
no journal, ,
no abstracts in English
Ebihara, Kenichi; Sugiyama, Yuri*; Matsumoto, Ryosuke*; Takai, Kenichi*; Suzudo, Tomoaki
no journal, ,
A hydrogen embrittlement model supposes that vacancies in steel which are generated by hydrogen charging and deformation concurrently cause directly embrittlement. Moreover, a characteristic peak appears in the hydrogen thermal desorption spectrum of such steel. Therefore, it is considered that vacancies and vacancy clusters resulting from vacancy aggregation can be estimated quantitatively by numerically simulating such a spectrum for verifying the model. In this study, the thermal desorption spectra of an iron specimen with strain-induced vacancies was measured, and the spectra was simulated using a model considering the behavior of vacancies and vacancy clusters. The possibility that diffusion of some kinds of vacancy clusters may be slower than the theoretical value was indicated from the result. Furthermore, we discuss the measurement of the thermal desorption curve immediately after the vacancy formation. This presentation includes a part of Metal. Mater. Trans. A52 (2021) 257.
