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Journal Articles

Toward mechanistic evaluation of critical heat flux in nuclear reactors, 2; Recent studies and future challenges toward mechanistic and reliable CHF evaluation

Okawa, Tomio*; Mori, Shoji*; Liu, W.*; Ose, Yasuo*; Yoshida, Hiroyuki; Ono, Ayako

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 63(12), p.820 - 824, 2021/12

The evaluation method of the critical heat flux based on the mechanism is needed for the efficient design and development of fuel in reactors and the appropriate safety evaluation. In this paper, the current researches relating to the mechanism of the critical heat flux are reviewed, and the issue to be considered in the future are discussed.

Journal Articles

Flow regime and void fraction predictions in vertical rod bundle flow channels

Han, X.*; Shen, X.*; Yamamoto, Toshihiro*; Nakajima, Ken*; Sun, Haomin; Hibiki, Takashi*

International Journal of Heat and Mass Transfer, 178, p.121637_1 - 121637_24, 2021/10

 Times Cited Count:1 Percentile:38.69(Thermodynamics)

Journal Articles

Observation of longitudinal magnetic fluctuations at a first-order ferromagnetic quantum phase transition in UGe$$_2$$

Noma, Yuichiro*; Kotegawa, Hisashi*; Kubo, Tetsuro*; To, Hideki*; Harima, Hisatomo*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*; Ito, Kohei*; Nakamura, Ai*; et al.

Journal of the Physical Society of Japan, 90(7), p.073707_1 - 073707_5, 2021/07

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

Journal Articles

Devil's staircase transition of the electronic structures in CeSb

Kuroda, Kenta*; Arai, Yosuke*; Rezaei, N.*; Kunisada, So*; Sakuragi, Shunsuke*; Alaei, M.*; Kinoshita, Yuto*; Bareille, C.*; Noguchi, Ryo*; Nakayama, Mitsuhiro*; et al.

Nature Communications (Internet), 11, p.2888_1 - 2888_9, 2020/06

 Times Cited Count:9 Percentile:68.19(Multidisciplinary Sciences)

Journal Articles

Impedance spectra analysis of thermoresponsive poly(acryloyl-$$_{L}$$-proline methyl ester) gel membrane in LiCl solution

Chen, J.; Asano, Masaharu; Tsubokawa, Norio*; Maekawa, Yasunari; Yamaki, Tetsuya; Yoshida, Masaru

Journal of Polymer Science, Part B; Polymer Physics, 43(20), p.2843 - 2851, 2005/10

 Times Cited Count:0 Percentile:0.01(Polymer Science)

Impedance spectra analysis of a thermo-responsive poly(acryloyl-$$_{L}$$-proline methyl ester) (poly(A-ProOMe)) hydrogel membranes in an aqueous solution of LiCl was carried out using a simple equivalent model. The hydrogel membrane was synthesized by $$gamma$$-radiation-induced polymerization and crosslinking of A-ProOMe monomer aqueous solution in a glass-cast. By means of the impedance spectra analysis, a novel method for the calculation of the ionic conductivity of the hydrogel membranes in LiCl solution was proposed. The calculated ionic conductivity was in agreement well with the determined value. In addition, effects of temperature and LiCl concentration on the impedance spectra and ionic conductivity of the gel membrane were analysized. Results indicated that the impedance spectra analysis is a very useful tool for evaluating the electric properties of gel membranes in an electrolyte solution. The poly(A-ProOMe) gel membrane in 1.0 M LiCl solution showed a high ionic conductivity of about 0.2 S/cm at 14$$^{circ}$$C. The temperature-dependence of the ionic conductivity was a complex nonlinear form due to the volume phase transition of the thermo-responsive poly(A-ProOMe) gel membrane, and the volume phase transition temperature appeared to be decreased with the increase in the LiCl concentration.

JAEA Reports

Minutes of the IFMIF technical meetings; May 17-20, 2005, Tokyo, Japan

IFMIF International Team

JAERI-Review 2005-027, 416 Pages, 2005/08

JAERI-Review-2005-027.pdf:48.34MB

The International Fusion Materials Irradiation Facility (IFMIF) Technical Meetings were held on May 17-20, 2005 at Japan Atomic Energy Research Institute (JAERI) Tokyo. The main objectives were (1) to review technical status of the subsystems; accelerator, target and test facilities, (2) to technically discuss interface issues between target and test facilities, (3) to review results of peer-reviews performed in the EU and Japan, (4) to harmonize design / experimental activities among the subsystems, (5) to review and discuss the Engineering Validation and Engineering Design Activity (EVEDA) tasks, and (6) to make a report of (1) - (5) to the IFMIF Executive Subcommittee. This report presents a brief summary of the Target Technical Meeting, Test Facilities Technical Meeting, Target / Test Facilities Interface Meeting, Accelerator Technical Meeting and the Technical Integration Meeting.

Journal Articles

Structural studies on liquids and glasses under high pressure and high temperature

Katayama, Yoshinori; Inamura, Yasuhiro*

Nuclear Instruments and Methods in Physics Research B, 238(1-4), p.154 - 159, 2005/08

 Times Cited Count:7 Percentile:50.13(Instruments & Instrumentation)

It is well know that many substances have different structures in the crystalline state and they exhibit first-order structural phase transitions by a change in pressure. On the other hand, pressure-induced structural changes in the liquid and glassy states were supposed to be monotonous. The recent development of synchrotron radiation sources enables us to perform structural studies on liquids and glasses under high pressure and high temperature conditions. These studies revealed that the changes in the liquid and glassy states are not necessarily monotonous. We will present recent results on liquid phosphorus and silica glass.

Journal Articles

Flux growth of $$^{57}$$Fe-enriched very high quality iron borate single crystal and observation of magnetic domain structure using X-ray double crystal topography

Mitsui, Takaya; Takei, Fumihiko*; Kitao, Shinji*; Seto, Makoto; Harami, Taikan; Zhang, X.*; Yoda, Yoshitaka*; Kikuta, Seishi*

Transactions of the Materials Research Society of Japan, 30(1), p.7 - 10, 2005/03

no abstracts in English

Journal Articles

Sedimentation of substitutional solute atoms in In-Pb system alloy under strong gravitational field; Experiments and simulations

Ono, Masao; Kinoshita, Takahiro*; Ueno, Hideto*; Huang, X.*; Osakabe, Toyotaka; Mashimo, Tsutomu

Materials Transactions, 46(2), p.219 - 224, 2005/02

 Times Cited Count:7 Percentile:52.75(Materials Science, Multidisciplinary)

Ultracentrifuge experiments were performed on the In-Pb system to study the sedimentation of atoms and phase equilibrium. After the experiments, the graded structures were obtained. Pb-rich phase (f.c.c) and In-rich phase (tetragonal) appeared at the strong- and weak-gravitational field sides of the sample, respectively, from starting state of $$alpha$$-phase. And, the continuous changes in lattice parameters were observed in each phase. These observation results showed that the graded structure was continuous in atomic scale, and was formed by the sedimentation of atoms. Composition profiles of the centrifuged samples for 31.3 h, 60 h and 150 h showed that the composition change reached the steady state within 60 hours. The diffusion coefficient for sedimentation was estimated to be about 8 times larger than that for usual diffusion by the simulation. The result indicated that the diffusion mechanism of the sedimentation was different from the conventional ones.

Journal Articles

Master plan and current status for feasibility study on thermal-hydraulic performance of reduced-moderation water reactors

Onuki, Akira; Takase, Kazuyuki; Kureta, Masatoshi*; Yoshida, Hiroyuki; Tamai, Hidesada; Liu, W.; Akimoto, Hajime

Proceedings of Japan-US Seminar on Two-Phase Flow Dynamics, p.317 - 325, 2004/12

We start R&D project to develop the predictable technology for thermal-hydraulic performance of Reduced-Moderation Water Reactor (RMWR) in collaboration with Power Company/reactor vendor/university since 2002. The RMWR can attain the favorable characteristics such as effective utilization of uranium resources, multiple recycling of plutonium, high burn-up and long operation cycle, based on matured BWR technologies. MOX fuel assemblies with tight lattice arrangement are used to increase the conversion ratio by reducing the moderation of neutron energy. Increasing the in-core void fraction also contributes to the reduction of neutron moderation. The confirmation of thermal-hydraulic feasibility is one of the most important R&D items for the RMWR because of the tight lattice configuration. In this paper, we will show the R&D plan and describe the current status on experimental and analytical studies. We will confirm the thermal-hydraulic performance in the tight-lattice bundles by this project and develop a predictable technology for the RMWR in future.

Journal Articles

Phase transitions of the mean-field Potts glass model in a field

Yokota, Terufumi

Physical Review B, 70(17), p.174422_1 - 174422_14, 2004/11

 Times Cited Count:2 Percentile:14.12(Materials Science, Multidisciplinary)

Phase transitions in the infinite-range p-state Potts glass model is studied in the presence of a field. Phase transition line into the transverse ordered phase is a straight line in a field-temperature phase diagram for small field and small effective ferromagnetic interaction. This is in contrast with the Gabay-Toulouse line for the vector spin-glass model. Replica symmetry breaking pattern is discussed near the phase transition line. Replica symmetry for the longitudinal order parameter is weakly broken at higher temperature than the transition line to the transverse ordered phase for p$$>$$3.2. For p$$>$$4.6, the transition to the transverse ordered phase reveals discontinuity in the order parameter just as the p$$>$$4 case without a field.

Journal Articles

Neutron science and high pressure; Inelastic neutron scattering associated with pressure-induced phase transition

Fujii, Yasuhiko

Koatsuryoku No Kagaku To Gijutsu, 14(2), p.113 - 118, 2004/05

no abstracts in English

JAEA Reports

Minutes of the IFMIF technical meeting; December 4-5, 2003, Kyoto, Japan

IFMIF International Team

JAERI-Review 2004-008, 219 Pages, 2004/03

JAERI-Review-2004-008.pdf:35.23MB

The IFMIF Technical Meeting was held on December 4-5, 2003 at Shiran-kaikan, Kyoto University. The main objectives are (i) to finalize the Comprehensive Design Report (CDR), (ii) to discuss IFMIF cost and organization, (iii) to review technical status of major systems, transition phase activities and EVEDA plan. This report presents a brief summary of the results of the meeting. Agenda, participants list and presentation materials are attached as Appendix.

Journal Articles

Phonon density of states in Sr$$_{2}$$FeCoO$$_{6-delta}$$ and SrBaFeCoO$$_{6-delta}$$; Effects induced by magnetic order and transport coherence

Rykov, A. I.*; Nomura, Kiyoshi*; Sawada, Tsuguo*; Mitsui, Takaya; Seto, Makoto*; Tamegai, Tsuyoshi*; Tokunaga, Masashi*

Physical Review B, 68(22), p.224401_1 - 224401_7, 2003/12

 Times Cited Count:8 Percentile:43.7(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

X-ray structural studies on elemental liquids under high pressures

Katayama, Yoshinori; Tsuji, Kazuhiko*

Journal of Physics; Condensed Matter, 15(36), p.6085 - 6103, 2003/09

 Times Cited Count:81 Percentile:93.05(Physics, Condensed Matter)

X-ray structural studies on several elemental liquids under high pressure are reviewed. Combination of synchrotron radiation sources and large volume presses enables us to carry out in-situ structural measurements on liquids at high pressures up to several GPa. The measurements have revealed that compressions of liquid alkali metals are almost uniform, whereas those of liquids that have covalent components in bonding are mostly anisotropic. In some elements, different types of volume dependence of the nearest neighbour distances are observed in different pressure ranges. This behaviour suggests that the liquid phase can be divided in regions. Although most of the observed structural changes are continuous, a discovery of an abrupt structural change in liquid phosphorus, which is completed over a pressure range of less than 0.05 GPa around 1GPa and 1050 $$^{circ}$$C, supports existence of a first-order liquid-liquid phase transition.

Journal Articles

Pressure-induced structural phase transitions and solid-state reactions in hydrogen bromide and hydrogen sulfide

Ikeda, Takashi

Koatsuryoku No Kagaku To Gijutsu, 13(3), p.224 - 231, 2003/08

Applying pressure to hydrogen-bonded crystals hydrogen bromide and hydrogen sulfide alters significantly the bonding nature and induces various kinds of phenomena: order-disorder transition, hydrogen-bond symmetrization, and molecular dissociation accompanied by the solid-state reactions. This article reviews the relationship between pressure-induced structural phase transitions and solid-state reactions, revealed from the cooperative works between high pressure experiments and the ab initio molecular dynamics simulations.

Journal Articles

Single crystal growth and magnetic properties of ferromagnetic URhGe$$_2$$

Matsuda, Tatsuma; Haga, Yoshinori; Tokiwa, Yoshifumi; Andrei, G.; Yamamoto, Etsuji; Okubo, Tomoyuki*; Onuki, Yoshichika

Acta Physica Polonica B, 34(2), p.1071 - 1074, 2003/02

We have successfully grown a single crystal of uranium intermetallic compound URhGe$$_2$$. The temperature dependence of electrical resistivity shows highly anisotropic behavior. Two anomalies, which correspond to the magnetic ordering temperatures, were observed in the resistivity, magnetic susceptibility and specific heat measurements at $$T_{rm M1}$$= 30 K and $$T_{rm M2}$$=25 K. The magnetic susceptibility also shows a large uniaxial anisotropy with a magnetic easy-axis along the [010] direction.

Journal Articles

Synchrotron radiation studies on pressure-induced structural changes in liquids and glasses

Katayama, Yoshinori; Inamura, Yasuhiro

Journal of Physics; Condensed Matter, 15(1), p.S343 - S350, 2003/01

 Times Cited Count:16 Percentile:62.08(Physics, Condensed Matter)

Combination of synchrotron radiation sources and large volume presses enable us to make in-situ observations of structural change in liquids and glasses at high pressures up to several GPa and high temperatures up to 1500K. A number of methods, X-ray diffraction, XAFS, density measurement by means of X-ray absorption, viscosity measurements by means of radiography, are now applicable for this purpose. We have systematically studied elemental liquid and found that a characteristic structural change occurs in a narrow pressure-temperature range in liquid selenium. Moreover we have found a sudden structural change in liquid phosphorus. Experimental results on phosphorus support a view that the change is a first-order liquid-liquid transition. In the talk, results of current attempt to detect sudden structural change in silica glass will be presented. A preliminary result of X-ray diffraction study on liquid water under high-pressure will be also reported.

Journal Articles

Defect-induced phase separation in relaxor Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_3$$ crystals

Yoneda, Yasuhiro; Matsumoto, Norimasa; Terauchi, Hikaru*; Yasuda, Naohiko*

Journal of Physics; Condensed Matter, 15(3), p.467 - 474, 2003/01

 Times Cited Count:5 Percentile:32.04(Physics, Condensed Matter)

Thermal properties of ordered and disordered Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_3$$ (PIN) single clystals were investigated. The defect-induced phase separation provided a good agreement of the instability of the relaxor nd antiferroelectric states of the PIN crystals.

Journal Articles

Single crystal growth and structural and magnetic properties of the uranium thernary intermetallic compound UCr$$_2$$Si$$_2$$

Matsuda, Tatsuma; Metoki, Naoto; Haga, Yoshinori; Ikeda, Shugo; Okubo, Tomoyuki*; Sugiyama, Kiyohiro*; Nakamura, Noriko*; Kindo, Koichi*; Kaneko, Koji; Nakamura, Akio; et al.

Journal of the Physical Society of Japan, 72(1), p.122 - 130, 2003/01

 Times Cited Count:10 Percentile:55.73(Physics, Multidisciplinary)

no abstracts in English

134 (Records 1-20 displayed on this page)