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Kumada, Takayuki; Iwahara, Daisuke*; Nishitsuji, Shotaro*; Akutsu, Kazuhiro*; Miura, Daisuke; Motokawa, Ryuhei; Sugita, Tsuyoshi; Torikai, Naoya*; Amino, Naoya*; Oku, Takayuki; et al.
Journal of Physical Chemistry C, 128(21), p.8797 - 8802, 2024/05
Times Cited Count:0 Percentile:0.00(Chemistry, Physical)We elucidated the entanglement of polybutadiene and silane coupling agent (SCA) molecules bound to Si substrates using spin-contrast-variation (SCV) neutron reflectivity (NR). In an annealed integral blend film of polybutadiene and SCA, a SCA layer generated on the Si substrate was composed of 70 vol. percent SCA molecules extended perpendicularly from the silicon substrate and entangled with 30 vol. percent polybutadiene molecules. By contrast, in an SCA-precoated polybutadiene film, the SCA-precoated layer is composed of densely packed SCA molecules forming crystal-like structure, and thus did not become entangled with the postcoated polybutadiene molecules. This poor entanglement resulted in poor binding between polybutadiene and Si substrate.
Sekine, Yurina; Nankawa, Takuya; Sugita, Tsuyoshi; Nagakawa, Yoshiyasu*; Shibayama, Yuki; Motokawa, Ryuhei; Ikeda-Fukazawa, Tomoko*
Nanoscale, 16(19), p.9400 - 9405, 2024/05
Times Cited Count:2 Percentile:62.87(Chemistry, Multidisciplinary)A tough carboxymethyl cellulose nanofiber (CMF)/ zirconium (Zr) hydrogel was obtained by freeze cross-linking method. The hydrogel was prepared by adding HCl solution containing Zr to frozen CMF and thawing it. The hydrogel showed high adsorptivity for fluoride. This simple gelation method provides useful insight for developing hydrogel-metal complexes.
Kumada, Takayuki; Motokawa, Ryuhei; Oba, Yojiro; Nakagawa, Hiroshi; Sekine, Yurina; Micheau, C.; Ueda, Yuki; Sugita, Tsuyoshi; Birumachi, Atsushi; Sasaki, Miki; et al.
Journal of Applied Crystallography, 56(6), p.1776 - 1783, 2023/12
Times Cited Count:11 Percentile:96.87(Chemistry, Multidisciplinary)The combination of the existing position-sensitive photomultiplier and the He main detector with focusing devices, and the newly installed front detectors in SANS-J at JRR-3 covers small-angle neutron scattering signals in the range of the magnitude of the scattering vector Q from 0.002 to 6 nm-1 gaplessly with three standard device layouts. The installation of the front detector and a graphical user interface system largely improved the usability of SANS-J.
Kawaguchi, Maho*; Shiba, Shigeki*; Iwahashi, Daiki*; Okawa, Tsuyoshi*; Gunji, Satoshi; Izawa, Kazuhiko; Suyama, Kenya
Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 8 Pages, 2023/10
The Nuclear Regulation Authority (NRA) has been working on an experimental approach for evaluating the criticality of fuel debris produced by the Fukushima Daiichi Nuclear Power Plant (FDNP) accident since 2014, collaborating with the Japan Atomic Energy Agency (JAEA). As part of the approach, JAEA has modified the STAtic experiment Critical facilitY (STACY) for critical experiments to evaluate characteriscs of pseudo-fuel debris. As the preliminary analyses, we verified critical characteristics with major nuclear data libraries for the proposed core configuration patterns. The three-dimensional continuous-energy Monte Carlo neutron and photon transport code, SERPENT-V2.2.0 was used with the latest JENDL, JENDL-5. As a result, larger multiplication factors of JENDL-5 across the modified STACY core configuration patterns were evaluated in comparison to the other libraries. And, H scattering and
U fission sensitivity coefficients of JENDL-5 were different from those of the other libraries. Comparing among analyses with those libraries, the updated S(
,
) of JENDL-5 might affect the result of critical characteristics in the critical analyses for the modified STACY core configuration.
Shiba, Shigeki*; Iwahashi, Daiki*; Okawa, Tsuyoshi*; Gunji, Satoshi; Izawa, Kazuhiko; Suyama, Kenya
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 9 Pages, 2023/05
The Nuclear Regulation Authority (NRA) has tackled the experimental approach for determining the criticality of pseudo-fuel debris plausibly simulating actual fuel debris since 2014, collaborating with the Japan Atomic Energy Agency. To elucidate the characteristics of the pseudo-fuel debris, the Japan Atomic Energy Agency modified the STACY (STAtic experiment Critical facilitY) to conduct critical experiments simulating fuel debris. Thus, we proposed three types of modified STACY core configurations. In critical experiments in the modified STACY core, it is important to judge whether the proposed modified STACY core configurations are representative of molten core-concrete interaction debris or not. In this study, we built pseudo-fuel debris models considering a volume ratio of pseudo-fuel debris to moderation (V/V
) and calculated uncertainty-based similarity values (C
) between the modified STACY core configurations and pseudo-fuel debris models using Tools for Sensitivity and Uncertainty Analysis Methodology Implementation-Indices and Parameters (TSUNAMI-IP) in SCALE 6.2. Consequently, the modified STACY core configuration loading structure rods we proposed completely resulted in high similarity to the pseudo-fuel debris models through V
/V
values. The main contributions to C
values were
U
,
U
, and
Fe (n,
), except for the pseudo-fuel debris model, including extremely high concrete components.
Narita, Hirokazu*; Nicolson, R. M.*; Motokawa, Ryuhei; Ito, Fumiyuki*; Morisaku, Kazuko*; Goto, Midori*; Tanaka, Mikiya*; Heller, W. T.*; Shiwaku, Hideaki; Yaita, Tsuyoshi; et al.
Inorganic Chemistry, 58(13), p.8720 - 8734, 2019/07
Times Cited Count:20 Percentile:77.42(Chemistry, Inorganic & Nuclear)Ueda, Yuki; Kikuchi, Kei; Sugita, Tsuyoshi; Motokawa, Ryuhei
Solvent Extraction and Ion Exchange, 37(5), p.347 - 359, 2019/07
Times Cited Count:10 Percentile:36.46(Chemistry, Multidisciplinary)We have newly-designed fluorous phosphate(TFP) for the effective Zr(IV) ion extractant as an alternative extractant against the conventional organic phosphate, tri--butyl phosphate(TBP). Zr(IV) ion extraction system using the TBP has many problems such as the formation of the third phase during liquid-liquid extraction. Here, we develop the fluorous extraction system based on the TFP-perfluorohexane for the Zr(IV) ion extraction to improve the Zr(IV) ion extraction system with an effective extractability and without the third phase formation. Our main findings were that the significant high extraction performance of the TFP for Zr(IV) ion as compared with TBP, and the origins of the high extraction performance of the TFP are related to the water and HNO
contents in the fluorous phase and the stability of the complex, Zr(No
)
(TFP)
.
Narita, Hirokazu*; Maeda, Motoki*; Tokoro, Chiharu*; Suzuki, Tomoya*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi
Analytical Sciences, 33(11), p.1305 - 1309, 2017/11
Times Cited Count:11 Percentile:37.83(Chemistry, Analytical)Hisamatsu, Shugo; Suzuki, Shinichi; Komoto, Shigeo*; Kishikawa, Keiki*; Yamamoto, Yusuke*; Motokawa, Ryuhei; Yaita, Tsuyoshi
Tetrahedron, 73(27-28), p.3993 - 3998, 2017/07
Times Cited Count:18 Percentile:61.22(Chemistry, Organic)Maeda, Motoki*; Narita, Hirokazu*; Tokoro, Chiharu*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi
Separation and Purification Technology, 177, p.176 - 181, 2017/04
Times Cited Count:22 Percentile:56.66(Engineering, Chemical)Motokawa, Ryuhei; Kobayashi, Toru; Endo, Hitoshi*; Ikeda, Takashi; Yaita, Tsuyoshi; Suzuki, Shinichi; Narita, Hirokazu*; Akutsu, Kazuhiro*; Heller, W. T.*
Journal of Nuclear Science and Technology, 53(8), p.1205 - 1211, 2016/08
Times Cited Count:1 Percentile:9.82(Nuclear Science & Technology)Motokawa, Ryuhei; Endo, Hitoshi*; Yokoyama, Shingo*; Ogawa, Hiroki*; Kobayashi, Toru; Suzuki, Shinichi; Yaita, Tsuyoshi
Langmuir, 30(50), p.15127 - 15134, 2014/12
Times Cited Count:27 Percentile:61.58(Chemistry, Multidisciplinary)Motokawa, Ryuhei; Endo, Hitoshi*; Yokoyama, Shingo*; Nishitsuji, Shotaro*; Kobayashi, Toru; Suzuki, Shinichi; Yaita, Tsuyoshi
Scientific Reports (Internet), 4, p.6585_1 - 6585_6, 2014/10
Times Cited Count:38 Percentile:69.79(Multidisciplinary Sciences)Awual, M. R.; Kobayashi, Toru; Shiwaku, Hideaki; Miyazaki, Yuji; Motokawa, Ryuhei; Suzuki, Shinichi; Okamoto, Yoshihiro; Yaita, Tsuyoshi
Chemical Engineering Journal, 225, p.558 - 566, 2013/06
Times Cited Count:206 Percentile:98.63(Engineering, Environmental)Awual, M. R.; Kobayashi, Toru; Miyazaki, Yuji; Motokawa, Ryuhei; Shiwaku, Hideaki; Suzuki, Shinichi; Okamoto, Yoshihiro; Yaita, Tsuyoshi
Journal of Hazardous Materials, 252-253, p.313 - 320, 2013/05
Times Cited Count:193 Percentile:97.55(Engineering, Environmental)Motokawa, Ryuhei; Suzuki, Shinichi; Ogawa, Hiroki*; Antonio, M. R.*; Yaita, Tsuyoshi
Journal of Physical Chemistry B, 116(4), p.1319 - 1327, 2012/02
Times Cited Count:38 Percentile:65.87(Chemistry, Physical)Terashima, Takaya*; Motokawa, Ryuhei; Koizumi, Satoshi*; Sawamoto, Mitsuo*; Kamigaito, Masami*; Ando, Tsuyoshi*; Hashimoto, Takeji*
Macromolecules, 43(19), p.8218 - 8232, 2010/10
Times Cited Count:42 Percentile:76.49(Polymer Science)Koga, Tsuyoshi*; Tanaka, Fumihiko*; Motokawa, Ryuhei; Koizumi, Satoshi*; Winnik, F. M.*
Macromolecular Symposia, 291-292(1), p.177 - 185, 2010/05
Times Cited Count:5 Percentile:59.27(Polymer Science)Koga, Tsuyoshi*; Tanaka, Fumihiko*; Motokawa, Ryuhei; Koizumi, Satoshi; Winnik, F. M.*
Macromolecules, 41(23), p.9413 - 9422, 2008/11
Times Cited Count:74 Percentile:88.98(Polymer Science)On the basis of results from a small-angle neutron scattering (SANS) study of aqueous solutions of a telechelic PNIPAM with octadecyl end groups, we developed a theoretical model of the self-assembly of this polymer in water as a function of temperature and concentration. This model leads us to the following description. In solutions of concentration 10 gL kept between 10 and 20
C, telechelic PNIPAMs (
) 22 200 gmol
) associate in the form of flower micelles, containing about 12 polymer chains, assembled in a three-layered core-shell morphology with an inner core consisting of the octadecyl units, a dense inner shell consisting of partly collapsed PNIPAM chains, and an outer shell of swollen hydrated chains. Drastic changes in the scattering profile of the solution heated above 31
C are attributed to the formation of mesoglobules (diameter of 40 nm) consisting of about 1000 polymer chains. On further heating, the aggregation number of the mesoglobules increases. It reaches a value of 9000 at 34
C and stays constant upon further heating. In solutions of lower concentration (1 gL
), association of flower micelles and mesoglobules does not occur; however, the structure of individual flower micelles and mesoglobules is not affected by the change in concentration. In solutions of 50 gL
in which flower micelles are expected to be partially connected by bridge chains, a peak attributed to correlation between flower micelles appears in the scattering profiles recorded at low temperature (10-20
C). In spite of the intermicellar bridging connection, the overall temperature dependence of the scattering profile at 50 gL
remains similar to that at 10 gL
. Distinct features of the self-assembled structures formed in aqueous telechelic PNIPAM solutions are discussed in terms of the interactions between water and the polymer main chains.
Okawa, Tsuyoshi; Greenspan, E.*
Nuclear Technology, 160(3), p.257 - 278, 2007/12
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Since all the ENHS (Encapsulated Nuclear Heat Source) cores designed so far have positive coolant void reactivity, the ENHS reactor core was investigated to have a negative coolant void reactivity feedback.