Upgrade of the small-angle neutron scattering diffractometer SANS-J at JRR-3

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

https://doi.org/10.1107/S1600576723009731

The combination of the existing position-sensitive photomultiplier and the 3He 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.

Preliminary analysis of randomized configuration patterns in modified STACY core

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.

Extraction performance of a fluorous phosphate for Zr(IV) from HNO solution; Comparison with tri--butyl phosphate

Ueda, Yuki; Kikuchi, Kei; Sugita, Tsuyoshi; Motokawa, Ryuhei

Solvent Extraction and Ion Exchange, 37(5), p.347 - 359, 2019/07

https://doi.org/10.1080/07366299.2019.1638015

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).

A Chemiluminescence sensor with signal amplification based on a self-immolative reaction for the detection of fluoride ion at low concentrations

Hisamatsu, Shugo; Suzuki, Shinichi; Komoto, Shigeo*; Kishikawa, Keiki*; Yamamoto, Yusuke*; Motokawa, Ryuhei; Yaita, Tsuyoshi

Tetrahedron, 73(27-28), p.3993 - 3998, 2017/07

https://doi.org/10.1016/j.tet.2017.05.084

Small-angle neutron scattering study of specific interaction and coordination structure formed by mono-acetyl-substituted dibenzo-20-crown-6-ether and cesium ions

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

https://doi.org/10.1080/00223131.2015.1102100

Collective structural changes in vermiculite clay suspensions induced by cesium ions

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

https://doi.org/10.1038/srep06585

Selective lanthanide sorption and mechanism using novel hybrid Lewis base (N-methyl-N-phenyl-1,10-phenanthroline-2-carboxamide) ligand modified adsorbent

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

https://doi.org/10.1016/j.jhazmat.2013.03.020

In situ and time-resolved small-angle neutron scattering observation of star polymer formation via arm-linking reaction in ruthenium-catalyzed living radical polymerization

Terashima, Takaya*; Motokawa, Ryuhei; Koizumi, Satoshi*; Sawamoto, Mitsuo*; Kamigaito, Masami*; Ando, Tsuyoshi*; Hashimoto, Takeji*

Macromolecules, 43(19), p.8218 - 8232, 2010/10

https://doi.org/10.1021/ma101235j

Theoretical modeling of associated structures in aqueous solutions of hydrophobically modified telechelic PNIPAM based on a neutron scattering study

Koga, Tsuyoshi*; Tanaka, Fumihiko*; Motokawa, Ryuhei; Koizumi, Satoshi; Winnik, F. M.*

Macromolecules, 41(23), p.9413 - 9422, 2008/11

https://doi.org/10.1021/ma800957z

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 20C, 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 31C 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 34C 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 (10-20C). 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.

High-energy spectroscopic study of the III-V nitride-based diluted magnetic semiconductor GaMnN

Hwang, J. I.*; Ishida, Yukiaki*; Kobayashi, Masaki*; Hirata, Gen*; Takubo, Ko*; Mizokawa, Takashi*; Fujimori, Atsushi; Okamoto, Jun; Mamiya, Kazutoshi*; Saito, Yuji; et al.

Physical Review B, 72(8), p.085216_1 - 085216_6, 2005/08

A2004-0178.pdf:0.19MB

https://doi.org/10.1103/PhysRevB.72.085216

no abstracts in English