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Kawai, Yusaku*; Park, J.*; Motokawa, Ryuhei; Ikura, Ryohei*; Murayama, Shunsuke*; Yamaoka, Kenji*; Fujii, Yoshihisa*; Ikemoto, Yuka*; Tanaka, Masaru*; Matsuba, Go*; et al.
ACS Applied Polymer Materials (Internet), 7(12), p.7767 - 7776, 2025/06
TaS
Park, P.*; Cho, W.*; Kim, C.*; An, Y.*; Avdeev, M.*; Iida, Kazuki*; Kajimoto, Ryoichi; Park, J.-G.*
Physical Review B, 109(6), p.L060403_1 - L060403_7, 2024/02
Times Cited Count：8 Percentile：87.36(Materials Science, Multidisciplinary)Park, Y.-J.*; Sawada, Atsushi; Ozutsumi, Takenori*; Tanaka, Tatsuya*; Hashimoto, Shuji*; Morita, Yutaka*
Proceedings of 3rd International Conference on Discrete Fracture Network Engineering (DFNE 2022) (Internet), 8 Pages, 2022/00
Safety analysis for underground disposal facilities for high-level radioactive waste requires thorough understanding of long-term groundwater flow and nuclide migration processes in geologic media. In the coastal subsurface systems, groundwater flow is defined by the complex interactions between freshwater of meteoric origin and denser saline water from the sea. In addition, sea levels are expected to fluctuate significantly due to a transgression and regression of the sea over the millions of years for safety analysis. This study presents long-term evolution of groundwater environment such as salinity concentration and flow velocity with focus of the interaction between fractures and matrix blocks in regional and near-field scale analysis framework for groundwater flow and nuclide migration for underground disposal facilities in hypothetical fractured crystalline coastal systems.
Park, J.*; Takayama, Toshio*; Asano, Masaharu; Maekawa, Yasunari; Kudo, Kazuaki*; Takayama, Toshio*
Polymer, 54(17), p.4570 - 4577, 2013/08
Times Cited Count：6 Percentile：17.61(Polymer Science)Graft-type sulfonated polybenzimidazole was prepared through radiation-induced graft polymerization of styrenes into an alicyclic polybenzimidazole film and subsequent sulfonation. The alicyclic polybenzimidazole, ChPBI, was prepared from 
-1,4-cyclohexanedicarboxylic acid and 3,3'-diaminobenzidine using typical polycondensation. Anisotropic domains with a size of several tens of micrometers were found in the ChPBI films casted from LiCl-containing 
,-dimethylacetamide. Irradiation of the ChPBI membranes with a 220 kGy dose of 
-rays created radical species with mean lifetimes of two days. The treatment of this membrane with a 50/50 (v/v) mixture of 1-propanol and styrene produced polystyrene graft chains. Sulfonation of the resulting grafted membrane with ClSOH
OH occurred selectively on the polystyrene grafts. The sulfonated films showed proton conductivity on the order of 10
to 10
S/cm with an ion exchange capacity between 2.1 and 2.9 mmol/g. SEM-EDX analysis of the membrane indicated the presence of macrophase separated domains up to 1 
m in diameter. The proton conductivity of the membrane did not decrease for 600 h at 120
C in liquid water.
Park, J.; Enomoto, Kazuyuki; Yamashita, Takashi*; Takagi, Yasuyuki*; Todaka, Katsunori*; Maekawa, Yasunari
Journal of Membrane Science, 438, p.1 - 7, 2013/07
Times Cited Count：15 Percentile：42.04(Engineering, Chemical)Alicyclic polyimides (APIs) were successfully applied to radiation-induced graft polymerization for developing polymer electrolyte membranes for fuel cells. The grafting into fully aromatized polyimide barely proceeded (grafting degrees (GDs) of less than 5%), whereas that of styrene into the API films proceeded with styrene GDs of up to 70%. In combination of electron spin resonance measurements and ultraviolet-visible (UV-VIS) spectroscopy, the radical species was identified as a long-lived intermediate and 10% of the radicals were consumed as grafting initiators. The moderate reaction conditions allowed for selective sulfonation on the polystyrene grafts, and not on the API substrates, to give API-based polymer electrolyte membranes (PEMs) with ion exchange capacities (IEC) of 1.7-2.8 mmol/g. The PEMs exhibited appropriate proton conductivity and low water uptake, together with excellent mechanical properties, compared with conventional PEMs such as Nafion.
Pace, D. C.*; Austin, M. E.*; Bass, E. M.*; Budny, R.*; Heidbrink, W. W.*; Hillesheim, J. C.*; Holcomb, C. T.*; Gorelenkova, M.*; Grierson, B. A.*; McCune, D. C.*; et al.
Physics of Plasmas, 20(5), p.056108_1 - 056108_18, 2013/05
Times Cited Count：35 Percentile：79.88(Physics, Fluids & Plasmas)Energetic ion transport due to microturbulence is investigated in MHD-quiescent plasmas by way of neutral beam injection in the DIII-D tokamak. A range of on-axis and off-axis beam injection scenarios are employed to vary relevant parameters such as the character of the background microturbulence and the value of Eb/Te, where Eb is the energetic ion energy and Te the electron temperature. In all cases it is found that any transport enhancement due to microturbulence is too small to observe experimentally. These transport effects are modeled using numerical and analytic expectations that calculate the energetic ion diffusivity due to microturbulence. It is determined that energetic ion transport due to coherent modes, including possible reductions in neutral beam current drive, is a considerably larger effect and should therefore be considered more important for ITER.
Sumita, Junya; Shibata, Taiju; Sawa, Kazuhiro; Fujita, Ichiro; Ohashi, Jun*; Takizawa, Kentaro*; Kim, W.*; Park, J.*
Ceramic Materials for Energy Applications; Ceramic Engineering and Science Proceedings, Vol.32, No.9, p.1 - 12, 2011/11
Since the temperature condition in Very High Temperature Reactor (VHTR), one of the Generation-IV reactor systems, is severe, the application of heat-resistant carbon fiber reinforced carbon matrix composite (C/C composite) for control rod elements is one of the important subjects for the VHTR development. JAEA focuses on the application of two-dimensional (2D-) C/C composites for control rod. The 2D-C/C composite has an anisotropy in properties for parallel and perpendicular to lamina directions. Irradiation effects of the 2D-C/C composite also show anisotropic behavior. It is hence important to consider the anisotropy in control rod design. To investigate the irradiation effects of the 2D-C/C composite on properties, irradiation test and post irradiation examination (PIE) were carried out and the irradiation effects were evaluated for the both directions. Since the C/C composite is composed of fibers and matrix, this geometry should be considered to evaluate the crack propagation in the composite. To assess the fracture behavior with crack propagation, bending test was carried out assuming a crack in the control rod and cracks in specimens were observed. This paper describes the irradiation effects of the 2D-C/C composite based on the PIE results considering the anisotropy. The evaluation results on equivalent fracture toughness and fracture mechanism are also discussed.
Sumita, Junya; Fujita, Ichiro; Shibata, Taiju; Makita, Taiyo*; Takagi, Takashi*; Kunimoto, Eiji*; Sawa, Kazuhiro; Kim, W. J.*; Park, J. Y.*
IOP Conference Series; Materials Science and Engineering, 18(16), p.162010_1 - 162010_4, 2011/09
Times Cited Count：1 Percentile：49.46(Materials Science, Ceramics)For control rod element of Very High Temperature Reactor, carbon fiber reinforced carbon matrix composite (C/C composite) is one of the major candidate materials for its high strength and thermal stability. Since the crack propagation of the C/C composite is complicated, the fracture behavior is one of the most important subjects of the design methodology for the control rod with the C/C composite. In this study, in order to assess the Mode-II fracture behavior of the two-dimensional (2D-) C/C composite which has the layer structure of laminas composed of fibers and matrix, bending test with oxidized end notched flexure specimen was carried out. The interlaminar fracture toughness decreased with increasing the oxidation for the 2D-C/C composite. The oxidized matrix causes reduction of fracture toughness and the reduction ratio is dependent on the matrix type. The crack initiates at the boundary between fiber bundles and grows along them without breaking the fiber. It is thought that the cracks which were initiated at the interface between matrix and fiber were gathered into the voids in the boundary between fiber bundles, and then the crack grows up in the matrix.
Inamura, Yasuhiro; So, J.-Y.*; Nakajima, Kenji; Suzuki, Jiro*; Nakatani, Takeshi; Kajimoto, Ryoichi; Otomo, Toshiya*; Moon, M.-K.*; Lee, C.-H.*; Yasu, Yoshiji*; et al.
JAEA-Technology 2010-047, 74 Pages, 2011/02
JAEA-Technology-2010-047.pdf:15.03MB
This report summarizes the two-year (2007-2009) activities of Korea-Japan collaboration of chopper software development. Here we have described the background of the collaboration and the main part of our work. We also discussed briefly a future plan of our collaboration starting in 2010. Some of detailed description on the management of the collaboration as well as related information is given in appendix.
Shibata, Taiju; Sumita, Junya; Makita, Taiyo*; Takagi, Takashi*; Kunimoto, Eiji*; Sawa, Kazuhiro; Kim, W. J.*; Jung, C. H.*; Park, J. Y.*
Nihon Kikai Gakkai Rombunshu, A, 76(764), p.383 - 385, 2010/04
no abstracts in English
Park, J.*; Enomoto, Kazuyuki; Yamashita, Takashi*; Takagi, Yasuyuki*; Todaka, Katsunori*; Maekawa, Yasunari
Journal of Photopolymer Science and Technology, 22(3), p.285 - 287, 2009/08
Times Cited Count：0 Percentile：0.00(Polymer Science)Alicyclic Polyimide (A-PI) films were utilized as a substrate of radiation-induced polymerization to prepare PEM for fuel cells. We successfully prepared the A-PI- PEM by radiation-induced grafting of styrene into A-PI films and subsequent sulfonation. The obtained A-PI-PEM has higher ion conductivity and mechanical and thermal properties, compared with conventional PEM (Nafion). Furthermore, the long-lived intermediates in irradiated A-PI films were observed in the UV-VIS spectra. In comparison with the decay profile of ESR spectra of irradiated A-PI films, the initiation radicals (600, 420 nm) and radical anion (720 nm) can be characterized in terms of the graft polymerization mechanism of A-PI films.
Sakakibara, Tetsuro; Aoyama, Yoshio; Yamaguchi, Hiromi; Sasaki, Naoto*; Nishikawa, Takeshi*; Murata, Minoru*; Park, J.*; Taniguchi, Shoji*; Fujita, Michiru*; Fukuda, Tomoyuki*; et al.
Proceedings of International Waste Management Symposium 2009 (WM '09) (CD-ROM), 15 Pages, 2009/03
The volume reduction treatment of solid waste system by ultra-high frequency induction furnace (UHFIF) was developed from FY2005 to FY2007. Basic data for melting performance were collected by non-radioactive experiments using the bench scale UHFIF with a crucible capacity of 10 liters. Based on the obtained data, engineering specifications were evaluated for a demonstration scale UHFIF with a crucible capacity of 30 liters. A new demonstration scale UHFIF was constructed and melting experiments of surrogate wastes were carried out by this furnace. It was confirmed that the demonstration scale UHFIF can melt ferrous metal, ceramics and aluminum all together and stabilize aluminum by oxidation to alumina. Density, chemical composition, and surface condition of the solidified substances were analyzed, and homogeneity of the solidified substances was confirmed. Melting behavior in the demonstration scale UHFIF was analyzed by computer simulation and simulation results agreed well with the experimental ones. From the design study for a full scale UHFIF with a crucible capacity of 100 liters, basic specifications were evaluated for the full scale UHFIF. Based on the obtained specification, melting behavior in the full scale UHFIF was analyzed by computer simulation.
Kim, W. J.*; Seo, M.-R.*; Park, J. Y.*; Sumita, Junya; Shibata, Taiju; Sawa, Kazuhiro
no journal, ,
Carbon-carbon (C/C) composites have been widely used for high-temperature structural applications because they possess excellent mechanical properties such as high specific strength and thermal shock resistance. In the nuclear industry, the composites have also been considered for plasma facing materials in fusion reactors and high-temperature structural parts in gas cooled reactors. In the high-temperature gas cooled reactor, the composites are being considered for the application of various high-temperature structural parts such as control rod components, core restraint belts, tie rods, upper plenum shroud, hot duct insulation cover sheets, and floor blocks. However, the carbon based materials are susceptible to oxidation at temperatures above 400 C. Therefore, the oxidation behavior and property degradation at high temperature under impure He or in air in case of accidental air ingress should be evaluated before the deployment of composites. In this study, the oxidation behavior of several nuclear-grade C/C composites was evaluated at various temperatures. Thermal and mechanical properties of the composites were also measured before and after oxidation. The oxidation experiments were performed in range of 500 to 1100 C under air or Ar atmosphere. Thermal diffusivity, flexural strength, tensile strength, and interlaminar shear strength of as-received and oxidized specimens were evaluated.
Yamaguchi, Hiromi; Miyamoto, Yasuaki; Sakakibara, Tetsuro; Hanamoto, Yukio; Aoyama, Yoshio; Sasaki, Nao*; Nishikawa, Tsutomu*; Murata, Minoru*; Muroi, Masayuki*; Park, J.*; et al.
no journal, ,
no abstracts in English
Inamura, Yasuhiro; Nakatani, Takeshi; Nakajima, Kenji; Kajimoto, Ryoichi*; Ikeuchi, Kazuhiko*; Otomo, Toshiya*; Suzuki, Jiro*; So, J.-Y.*; Park, J.-G.*; Arai, Masatoshi
no journal, ,
We report the current status of software development for chopper spectrometers at Materials and Life Science Experimental Facility (MLF), J-PARC. This development work consists of four parts mainly, i.e. the experiment control system on spectrometer (data acquisition and devices), support for decisions of experimental conditions, data reduction and visualization. Our software, named Utsusemi, has already been utilized in actual users measurements, while we are proceeding with developments for more effective use of high flux neutrons. Especially, we have successfully demonstrated a measurement of a single crystal of 3D spin system; several tens of measurements by rotating the sample, and visualization of the data forming intensity maps in large Q space. This has been achieved by development of software to perform automatic devices control (sample rotation and data acquisition) and to handle huge data for visualization.
Park, J.; Takayama, Toshio*; Kudo, Kazuaki*; Maekawa, Yasunari
no journal, ,
PEMs for fuel cells prepared by radiation-induced graft polymerization of styrene onto APBI and subsequent sulfonation showed low mechanical property. PBI, exhibited no grafting reactivity, was employed as a blend polymer to APBI to increase mechanical property of PEMs. Polymer blend (1/1) film showed grafting reactivity as high as APBI even though it contained only 50% of APBI. This might be due to the enhanced graft polymerization of styrene on APBI which was promoted by the increased amorphous regions in the polymer blend film. Sulfonated polymer blend film showed similar proton conductivity with PEMs of APBI, while they showed lower water uptakes and higher mechanical property.
Aoyama, Yoshio; Yamaguchi, Hiromi; Sakakibara, Tetsuro; Hanamoto, Yukio; Murata, Minoru*; Sasaki, Nao*; Nishikawa, Tsutomu*; Taniguchi, Shoji*; Shimazaki, Shinichi*; Park, J.*; et al.
no journal, ,
no abstracts in English
Aoyama, Yoshio; Yamaguchi, Hiromi; Sakakibara, Tetsuro; Hanamoto, Yukio; Murata, Minoru*; Sasaki, Nao*; Nishikawa, Tsutomu*; Taniguchi, Shoji*; Shimazaki, Shinichi*; Park, J.*; et al.
no journal, ,
no abstracts in English
Aoyama, Yoshio; Yamaguchi, Hiromi; Sakakibara, Tetsuro; Hanamoto, Yukio; Murata, Minoru*; Sasaki, Nao*; Nishikawa, Tsutomu*; Taniguchi, Shoji*; Shimazaki, Shinichi*; Park, J.*; et al.
no journal, ,
no abstracts in English
Inamura, Yasuhiro; Nakajima, Kenji; Kajimoto, Ryoichi; Otomo, Toshiya*; Nakatani, Takeshi; Suzuki, Jiro*; Arai, Masatoshi; So, J.-Y.*; Park, J.-G.*; Perring, T.*; et al.
no journal, ,
We report the plan and current status of development for software used on high-intensity chopper spectrometer, 4SEASONS, and Cold Neutron Disk-Chopper Spectrometer, CNDCS, at Materials and Life Science Facility(MLF), J-PARC. We begin to design software packages based on many required functions for performing experiments and analysis, for example control spectrometer system (data acquisition, devices), suggestion of experiment conditions, visualization and so on. This project progresses with software company. On the other hand, we started to collaborate with Korean group about the development of analysis software for inelastic scattering. In this presentation, we will present the current status and plan for software development including collaboration with Korean group.
