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Journal Articles

Dynamics of water in a catalyst layer of a fuel cell by quasielastic neutron scattering

Ito, Kanae; Yamada, Takeshi*; Shinohara, Akihiro*; Takata, Shinichi; Kawakita, Yukinobu

Journal of Physical Chemistry C, 125(39), p.21645 - 21652, 2021/10

 Times Cited Count:0

Journal Articles

Neutron scattering studies on short- and long-range layer structures and related dynamics in imidazolium-based ionic liquids

Nemoto, Fumiya*; Kofu, Maiko; Nagao, Michihiro*; Oishi, Kazuki*; Takata, Shinichi; Suzuki, Junichi*; Yamada, Takeshi*; Shibata, Kaoru; Ueki, Takeshi*; Kitazawa, Yuzo*; et al.

Journal of Chemical Physics, 149(5), p.054502_1 - 054502_11, 2018/08

 Times Cited Count:12 Percentile:72.95(Chemistry, Physical)

Journal Articles

Study on self-wastage phenomenon at heat transfer tube in steam generator of sodium-cooled fast reactor with consideration of thermal coupling of fluid and structure

Kojima, Saori*; Uchibori, Akihiro; Takata, Takashi; Ohno, Shuji; Fukuda, Takeshi*; Yamaguchi, Akira*

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 8 Pages, 2016/11

Analytical evaluation on a self-wastage phenomenon at heat transfer tubes in the steam generator of sodium cooled fast reactors has been performed by using the sodium-water reaction analysis code SERAPHIM. In this study, a fluid-structure thermal coupling model was developed and incorporated in the SERAPHIM code to evaluate heat transfer between the sodium-side reacting flow and the outer surface of the heat transfer tube. The effect of the fluid-structure thermal coupling model on the temperature field was demonstrated through the numerical analyses.

Journal Articles

Stripline beam position monitors with improved frequency response and their coupling impedances

Shobuda, Yoshihiro; Chin, Y. H.*; Takata, Koji*; Toyama, Takeshi*; Nakamura, Keigo*

Proceedings of 57th ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams (HB 2016) (Internet), p.523 - 528, 2016/08

In J-PARC MR, there is a concern that electron cloud instabilities may appear and limit the beam current at future higher power operations. For the case, we have developed a wider-band beam position monitor by deforming the electrode shapes. The modification of the electrode can be done without significant enhancement of the beam coupling impedance. For typical electrode shapes, we show the coupling impedances as well as the frequency responses of the electrodes.

Journal Articles

Triangle and concave pentagon electrodes for an improved broadband frequency response of stripline beam position monitors

Shobuda, Yoshihiro; Chin, Y. H.*; Takata, Koji*; Toyama, Takeshi*; Nakamura, Keigo*

Physical Review Accelerators and Beams (Internet), 19(2), p.021003_1 - 021003_15, 2016/02

 Times Cited Count:1 Percentile:13.76(Physics, Nuclear)

The frequency domain performance of a stripline beam position monitor depends largely on the longitudinal shape of its electrode. To attain a good impedance matching along the electrode, it needs to be precisely bent down toward its downstream in proportion to its width. In this report, we first propose a triangle electrode for easy fabrication and set-up. Theoretical and simulation results show that the simple triangle electrode has a remarkably flatter frequency response than the rectangle one. The frequency response, in particular at high frequencies, can be further improved by attaching an "apron" plate, perpendicular to the upstream edge of the electrode. The overshooting of the frequency response at low frequency can be eliminated by replacing the straight sidelines of the triangle by three-point polylines. We found that the concave pentagon electrode achieves a wide and flat frequency response up to about $$4$$ GHz for the J-PARC Main Ring.

Journal Articles

Resonance structures in the impedance of a ceramic break and the measured results

Shobuda, Yoshihiro; Toyama, Takeshi*; Chin, Y. H.*; Takata, Koji*

Proceedings of 54th ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams (HB 2014) (Internet), p.74 - 78, 2015/03

Journal Articles

Recent developments of instruments in a spallation neutron source at J-PARC and those prospects in the future

Arai, Masatoshi; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Nakajima, Kenji; Shibata, Kaoru; Takahashi, Nobuaki; Suzuki, Junichi*; Takata, Shinichi; Yamada, Takeshi*; et al.

Journal of the Physical Society of Japan, 82(Suppl.A), p.SA024_1 - SA024_14, 2013/01

 Times Cited Count:6 Percentile:47.11(Physics, Multidisciplinary)

The paper describes developments of neutron scattering instruments in J-PARC neutron facility, which is a short pulse spallation source operated at a repetition rate 25 Hz and has a proton power 1 MW. New concept has been adopted to utilize high intensity coupled moderator even for a high resolution inelastic scattering instruments by taking a pulse shaping chopper system. Advanced technique has been also realized by taking an ability of event-recording system altogether with an improvement of a chopper system, realizing multi-Ei method. The paper also touches upon a general design concept for diffractometers in accordance with the source characteristics.

Journal Articles

Simulation of controlled longitudinal emittance blow-up in J-PARC RCS

Yamamoto, Masanobu; Nomura, Masahiro; Schnase, A.; Shimada, Taihei; Tamura, Fumihiko; Ezura, Eiji*; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Takagi, Akira*; et al.

Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.2952 - 2954, 2012/05

In J-PARC RCS, the high intensity beam is delivered to the MR. The longitudinal beam emittance at the RCS extraction should be optimized to avoid the beam loss after the MR injection. In order to match the longitudinal emittance shape between the RCS and the MR, it is desirable to enlarge the longitudinal emittance during the RCS acceleration. We have performed the particle tracking simulation for the controlled longitudinal emittance blow up in the RCS.

Journal Articles

Numerical study on passive control of thermal striping phenomenon using Lorentz force in fast reactor

Takata, Takashi*; Fukuda, Takeshi*; Yamaguchi, Akira; Uchibori, Akihiro; Kimura, Nobuyuki; Kamide, Hideki

Proceedings of 18th International Conference on Nuclear Engineering (ICONE-18) (CD-ROM), 7 Pages, 2010/05

Liquid sodium, used as a coolant of fast reactor (FR), is an electromagnetic fluid. When a magnetic field is embedded to liquid sodium flow, the Lorentz force will be induced and flow structure such as a turbulent mixing phenomenon will be influenced. In a FR piping system, thermal fatigue is one of key issues that may be occurred after a piping junction of different fluid temperature. In the present paper, a numerical study of sodium flow induced by the Lorentz force on a turbulent mixing after the junction has been carried out. The large eddy simulation (LES) coupled with the electromagnetic field analysis is used for this purpose. The numerical results showed that the temperature fluctuation due to turbulent mixing weakens after it runs through the magnetic field caused by the Lorentz force and thus the thermal fatigue will be suppressed. Accordingly, it is concluded that the passive control of the thermal fatigue will be possible by adding the magnetic field.

Journal Articles

Direct observation and control of liquid sodium flow dynamics using VUV-LIF-PIV technique under $$E$$$$times$$$$B$$ Lorentz force

Fukuda, Takeshi*; Takata, Takashi*; Horiike, Hiroshi*; Kimura, Nobuyuki; Kamide, Hideki

Proceedings of 18th International Conference on Nuclear Engineering (ICONE-18) (CD-ROM), 6 Pages, 2010/05

It was successfully proven that Na is reasonably transparent to the VUV (vacuum ultraviolet) laser radiation, although the liquid Na surface is highly reflective, being like a mirror to human eyes. The impact of this result is that the velocity field information inside the liquid Na can be visualized by implementing the well developed PIV (particle image velocimetry) technique. A large eddy simulation (LES) code has also been developed for comparison with the experimental results. Furthermore, the newly developed Na loop is designed so as to enable the application of electric and magnetic field in the orthogonal direction to each other that vigorous dynamics of vortices inside the liquid Na are resolved in the phase space under the Lorentz force.

Journal Articles

Plasma physics and radiation hydrodynamics in developing an extreme ultraviolet light source for lithography

Nishihara, Katsunobu*; Sunahara, Atsushi*; Sasaki, Akira; Nunami, Masanori*; Tanuma, Hajime*; Fujioka, Shinsuke*; Shimada, Yoshinori*; Fujima, Kazumi*; Furukawa, Hiroyuki*; Kato, Takako*; et al.

Physics of Plasmas, 15(5), p.056708_1 - 056708_11, 2008/00

 Times Cited Count:106 Percentile:97.57(Physics, Fluids & Plasmas)

Journal Articles

Structural basis for the fast phase change of Ge$$_{2}$$Sb$$_{2}$$Te$$_{5}$$; Ring statistics analogy between the crystal and amorphous states

Kohara, Shinji*; Kato, Kenichi*; Kimura, Shigeru*; Tanaka, Hitoshi*; Usuki, Takeshi*; Suzuya, Kentaro; Tanaka, Hiroshi*; Moritomo, Yutaka*; Matsunaga, Toshiyuki*; Yamada, Noboru*; et al.

Applied Physics Letters, 89(20), p.201910_1 - 201910_3, 2006/11

 Times Cited Count:183 Percentile:97.85(Physics, Applied)

The three-dimensional atomic configuration of amorphous Ge$$_{2}$$Sb$$_{2}$$Te$$_{5}$$ were derived by reverse Monte Carlo simulation with synchrotron-radiation X-ray diffraction data. The authors found that amorphous Ge$$_{2}$$Sb$$_{2}$$Te$$_{5}$$ can be regarded as "even-numbered ring structure", because the ring statistics is dominated by four- and six-fold rings analogous to the crystal phase. On the other hand, the formation of Ge-Ge homopolar bonds in amorphous GeTe constructs both odd- and even-numbered rings. They believe that the unusual ring statistics of amorphous Ge$$_{2}$$Sb$$_{2}$$Te$$_{5}$$ is the key for the fast crystallization speed of the material.

JAEA Reports

Feasibility Study on Commercialization of Fast Breeder Reactor Cycle Systems, Interim Report of Phase2 -Technical Study Report for Nuclear Fuel Cycle Systems-

Sato, Koji; Koma, Yoshikazu; Inoue, Akira; Yonezawa, Shigeaki; Takata, Takeshi; Nakabayashi, Hiroki; Namekawa, Takashi; Kawaguchi, Koichi

JNC TN9400 2004-036, 1051 Pages, 2004/06

JNC-TN9400-2004-036.pdf:90.95MB

The plant concept concerning the fuel cycle systems (combination of the reprocessing and the fuel fabrication )has been constructed to reduce their total cost by the introduction of various innovative techniques and to apply their utmost superior efficiency from such standpoints of a decrease in the environmental burden, better resource utilization and proliferation resistance improvement by the low decontamination transuranium element (TRU) recycle. For economical efficiency, less than 0.8 yen/kWh which is the demand value (total of the reprocessing expense and the fuel fabrication expense) of the fuel cycle expense satisfied each combination case at 200 tHM/y scale provisionally set for large-scale facilities. On the other hand, the combination case with a low breeder reactor core has satisfied the demand value, with improvement of the average burnup by the radial direction blanket fuel deletion contributing to the decrease of the fuel cycle expense at 50 tHM/y scale provisionally set for small-scale facilities.

Journal Articles

Conceptual Design Study on Advanced Aqueous Reprocessing System for Fast Reactor Fuel Cycle

Takata, Takeshi; Koma, Yoshikazu; Sato, Koji; Kamiya, Masayoshi; Shibata, Atsuhiro; Nomura, Kazunori; Ogino, Hideki; Koyama, Tomozo; Aose, Shinichi

Journal of Nuclear Science and Technology, 41(3), 307 Pages, 2004/00

 Times Cited Count:27 Percentile:85.48(Nuclear Science & Technology)

The design study of aqueous reprocessing system has been progressed for the feasibility study on commercialized fast reactor cycle systems. Based on the PUREX process,an aqueous reprocessing process with the addition of a uranium crystallization step and

JAEA Reports

TECHNICAL STUDY REPORT ON REPROCESSING SYSTEMS, Investigation on Alternatives for Advanced Aqueous Reprocessing System

Koma, Yoshikazu; Takata, Takeshi; Kamiya, Masayoshi; Sato, Koji

JNC TN9410 2003-010, 112 Pages, 2003/12

JNC-TN9410-2003-010.pdf:4.73MB

This report summarizes the design work made bay the reprocessing Technoplogy Group in 2002 FYJ and includes the followings: advanced aqueous reprocesing, supercritical liquid direct extraction as an alternative, Am and Cm recovery and FP recovery.

Journal Articles

Design Study on Minor Actinides Recovery for the NEXT Reprocessing

Koma, Yoshikazu; Takata, Takeshi; Sato, Koji; Sato, Koji

Proceedings of International Conference on Advanced Nuclear Energy and Fuel Cycle Systems (GLOBAL 2003) (CD-ROM), p.1939 - 1944, 2003/00

As a part of the fasibility study on commercialized fast cycle systems,conceptual design study on aqueous recovery process of Am and Cm was conducted in order to choose the most promising method for future reprocessing plant. Process flow diagram,material balance and arrangement of equipment were made for the three alternative methods. The SETFICS is a solvent extraction using TRUEX solvent and DTPA-nitrate solution to obtain actinides (III) products wothout laight lanthanides. The MAREC is an extraction chromatography using a porous silica support. Amine extraction combines oxdation of actinides(III) to (IV) and extractionof polyanionic actinides(IV) complex into amine mixed solvent.Definite difference was not found in technical feasibility and safety of them at the present.Comparing waste generation and cost for apparatus, the MAREC process seems to have an advantage.

Oral presentation

Liquid sodium flow dynamics studies using nonlinear wavelength conversion VUV laser, 2; Gas entrainment at free surface and application to sodium flow

Kamide, Hideki; Kimura, Nobuyuki; Ezure, Toshiki; Uchibori, Akihiro; Hayashi, Kenji; Fukuda, Takeshi*; Takata, Takashi*

no journal, , 

Gas entrainment at free surface in a reactor vessel is one of the significant issues in a design of a compact sodium cooled fast reactor. VUV laser is planned to apply visualization of liquid-gas surface shape during the gas entrainment in a sodium test. The sodium experiments were carried out for the onset criteria of the gas entrainment due to a free surface vortex. Water experiment using the same geometry with that in the sodium test was also performed. Onset condition maps in the sodium and water tests were in good agreement.

Oral presentation

Development of the intense smaller-angle neutron scattering instrument TAIKAN in J-PARC, 3

Suzuki, Junichi; Takata, Shinichi; Shinohara, Takenao; Oku, Takayuki; Kira, Hiroshi; Nakatani, Takeshi; Inamura, Yasuhiro; Ito, Takayoshi; Suzuya, Kentaro; Aizawa, Kazuya; et al.

no journal, , 

no abstracts in English

Oral presentation

Development of the smaller-angle neutron scattering instrument (TAIKAN) in J-PARC and its application to structural analysis of iron steels

Suzuki, Junichi; Takata, Shinichi; Shinohara, Takenao; Oku, Takayuki; Kira, Hiroshi; Nakatani, Takeshi; Inamura, Yasuhiro; Ito, Takayoshi; Suzuya, Kentaro; Aizawa, Kazuya; et al.

no journal, , 

no abstracts in English

Oral presentation

Current status of sample environment in MLF, J-PARC

Kawamura, Seiko; Yokoo, Tetsuya*; Kambara, Wataru; Inamura, Yasuhiro; Nakatani, Takeshi; Torii, Shuki*; Kajimoto, Ryoichi; Nakajima, Kenji; Kaneko, Koji; Kawakita, Yukinobu; et al.

no journal, , 

Materials and Life Science Experimental Facility at J-PARC started the user program in December 2008. Various neutron experiments are currently performed there in wide range of scientific researches and industrial applications. Standardization of sample environment (SE) equipments is one of the most important things at the beginning stage. Especially in our country, it often happens that each instrument carries and operates SE devices independently. This situation results in an excess of the cost and incompatibility among the instruments unless we have any guidelines. Thus the SE team has discussed the SE-protocol, in which flange size, thermometers, controllers etc. are standardized. This should bring about saving the cost and manpower and increasing compatibility. The SE team is now discussing user support system in SE, preparation of the SE area, and so on. The technical staff members started working on practical things such as cooling test of cryostats.

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