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Journal Articles

Molecular dynamics simulations of physical properties of water and cations in montmorillonite interlayer; Application to diffusion model

Yotsuji, Kenji*; Tachi, Yukio; Kawamura, Katsuyuki*; Arima, Tatsumi*; Sakuma, Hiroshi*

Nendo Kagaku, 58(1), p.8 - 25, 2019/00

Molecular dynamics (MD) simulations were conducted to investigate physical properties of water and cations in montmorillonite interlayer nanopores. The swelling behaviors and hydration states were firstly evaluated as functions of interlayer cations and layer charge. The diffusion coefficients of water and cations in interlayer nanopores were decreased in comparison with those in bulk water and came closer to those in bulk water when basal spacing increased. The viscosity coefficients of interlayer water estimated indicated a significant effect of viscoelectricity at 1- and 2-layer hydration states and higher layer charge of montmorillonite. These trends from MD calculations were confirmed to be consistent with existing measured data and previous MD simulation. In addition, model and parameter related to viscoelectric effect used in the diffusion model was refined based on comparative discussion between MD simulations and measurements. The series of MD calculations could provide atomic level understanding for the developments and improvements of the diffusion model for compacted montmorillonite.

Journal Articles

Thermophysical properties of sodium-concrete reaction products

Kawaguchi, Munemichi; Miyahara, Shinya; Uno, Masayoshi*

Netsu Sokutei, 45(1), p.2 - 8, 2018/01

Liquid sodium (Na) has been used as the coolant of fast reactors for the various merits, such as the high thermal conductivity. On the other hand, it is postulated that a steel liner may fail and lead to a sodium-concrete reaction (SCR) during the Na-leak accident. Because of concrete ablation and release of hydrogen gas due to the chemical reactions between Na and concrete components, the SCR is one of the important phenomena in the Na-leak accident. In the study, fundamental experiments related to the SCR were performed using Na and concrete powder. Here, the used concrete powder is milled siliceous concrete which is usually used as the structural concrete in Japanese nuclear power plants. The obvious temperature changes at 3 temperature regions were observed for the reaction process such as Na-melt, NaOH-SiO$$_{2}$$ and Na-H$$_{2}$$O-SiO$$_{2}$$ reaction, which occurred around 100, 300 and 500$$^{circ}$$C, respectively. Especially, the violent reaction around 500$$^{circ}$$C caused the temperature peak to $$836 sim 853^{circ}$$C, and the reaction heat of $$0.15 sim 0.23$$ kW/g was estimated under the Na-concrete mixing ratio such as $$gammaapprox 0.32$$. The main components of the reaction products was identified as Na$$_{2}$$SiO$$_{3}$$ with X-ray diffraction technique. Moreover, the measured thermophysical properties such as melting point, density, specific heat, thermal conductivity and viscosity were similar to those of $$x$$Na$$_{2}$$O-$$(1-x)$$SiO$$_{2}$$ ($$xleq 0.5$$).

Journal Articles

Viscosity and density measurements of melts and glasses at high pressure and temperature by using the multi-anvil apparatus and synchrotron X-ray radiation

Otani, Eiji*; Suzuki, Akio*; Ando, Ryota*; Urakawa, Satoru*; Funakoshi, Kenichi*; Katayama, Yoshinori

Advances in High-Pressure Technology for Geophysical Applications, p.195 - 209, 2005/09

This paper summarizes the techniques for the viscosity and density measurements of silicate melt and glasses at high pressure and temperature by using the X-ray radiography and absorption techniques in the third generation synchrotron radiation facility, SPring-8, Japan. The falling sphere method using in situ X-ray radiography makes it possible to measure the viscosity of silicate melts to the pressures above 6 GPa at high temperature. We summarize the details of the experimental technique of the viscosity measurement, and the results of the measurements of some silicate melts such as the albite and diopside-jadeite systems. X-ray absorption method is applied to measure the density of the silicate glasses such as the basaltic glass and iron sodium disilicate glass up to 5 GPa at high temperature. A diamond capsule, which is not reactive with the glass, is used for the density measurement of the glasses. The present density measurement of the glasses indicates that this method is useful for measurement of the density of silicate melts at high pressure and temperature.

Journal Articles

Effects of parallel viscosity on rotation of magnetic islands in tokamaks

Konovalov, S. V.; Mikhailovskii, A. B.*; Tsypin, V. S.*; Kovalishen, E. A.*; Shirokov, M. S.*; Ozeki, Takahisa; Takizuka, Tomonori

Physics Letters A, 318(4-5), p.429 - 434, 2003/11

 Times Cited Count:7 Percentile:47.65(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Viscosity change and structural transition of molten Fe at 5 GPa

Terasaki, Hidenori*; Kato, Takumi*; Urakawa, Satoru*; Funakoshi, Kenichi*; Sato, Kiminori*; Suzuki, Akio*; Okada, Taku

Geophysical Research Letters, 29(8), p.68_1 - 68_3, 2002/05

The in situ viscosity measurements of the pure molten Fe under high pressures were made by falling sphere X-ray radiography method. Viscosity coefficients at about 2000 K were 15-24 mPa s at 2.7-5.0 GPa, and 4-9 mPa s at 5.0-7.0 GPa. Drastic decrease was found at around 5 GPa, at which stable solid phase below the melting temperatures change from delta (bcc) to gamma (fcc) phases. The observation indicates the possibility that the structural change in the molten Fe occurs in a narrow pressure interval (1 GPa) at the similar condition with the phase transformation in the solid.

Journal Articles

Fine SiC fiber synthesized from organosilicon polymers; Relationship between spinning temperature and melt viscosity of precursor polymers

Idesaki, Akira; Narisawa, Masaki*; Okamura, Kiyohito*; Sugimoto, Masaki; Tanaka, Shigeru; Morita, Yosuke; Seguchi, Tadao; Ito, Masayoshi*

Journal of Materials Science, 36(23), p.5565 - 5569, 2001/12

 Times Cited Count:36 Percentile:77.69(Materials Science, Multidisciplinary)

A very fine silicon carbide (SiC) fiber with diameter of 6 $$mu$$ m, about a half of that of a commercially available SiC fiber, was synthesized from a polymer blend of polycarbosilane (PCS) and polyvinylsilane (PVS). The fine SiC fiber was obtained by optimizing the composition and the spinning temperature of PCS-PVS polymer blends. In order to determine these optimum conditions, the relationship between temperature and melt viscosities of the polymer blends was investigated. As a result, it was found that the optimum spinning temperature range was within a temperature range where the melt viscosity is 5-10Pa$$cdot$$s. Moreover, by blending PVS with PCS, the spinning temperature of the polymer blends was lowered, the spinnability of polymer system was improved, and finer polymer fiber was obtained compared with PCS. The optimum content of PVS in the polymer blend was 15-20wt%.

Journal Articles

The Effect of temperature, pressure, and sulfur content on viscosity of the Fe-FeS melt

Terasaki, Hidenori*; Kato, Takumi*; Urakawa, Satoru*; Funakoshi, Kenichi*; Suzuki, Akio*; Okada, Taku; Maeda, Makoto*; Sato, Jin*; Kubo, Tomoaki*; Kasai, Shizu*

Earth and Planetary Science Letters, 190(1-2), p.93 - 101, 2001/07

 Times Cited Count:47 Percentile:68(Geochemistry & Geophysics)

The Fe-FeS melt is thought to be the major candidate of the outer core material. Its viscosity is one of the most important physical properties to study the dynamics of the convection in the outer core. We performed the in situ viscosity measurement of the Fe-FeS melt under high pressure using X-ray radiography falling sphere method with a novel sample assembly. Viscosity was measures in the temperature, pressure, and compositional conditions of 1233-1923 K, 1.5-6.9 GPa, and Fe-Fe $$_{72}$$ S $$_{28}$$ (wt %), respectively. The viscosity coefficients obtained by 17 measurements change systematically in the range of 0.008-0.036 Pa s. An activation energy of the viscous flow, 30 kJ/mol, and the activation volume, 1.5 cm $$^{3}$$ /mol, are determined as the temperature and pressure dependence, and the viscosity of the Fe $$_{72}$$ S $$_{28}$$ melt is found to be smaller than that of the Fe melt by 15 %. These tendencies can be well correlated with the structural variation of the Fe-FeS melt.

Journal Articles

Large coherent structure formation by magnetic stretching term in two-dimensional MHD turbulence

*; *

Journal of the Physical Society of Japan, 67(12), p.4302 - 4303, 1998/12

 Times Cited Count:7 Percentile:52.01(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Molecular dynamics calculation of structure and transport properties for molten YCl$$_{3}$$

Okamoto, Yoshihiro; Hayashi, Hirokazu; Ogawa, Toru

Journal of Non-Crystalline Solids, 205-207(PT.1), p.139 - 142, 1996/00

no abstracts in English

JAEA Reports

Thermal property correlation package of hydrogen, carbon monoxide, carbon dioxide and methane

Hada, Kazuhiko

JAERI-M 93-029, 99 Pages, 1993/03

JAERI-M-93-029.pdf:2.39MB

no abstracts in English

Journal Articles

Nuclear spin relaxation in molten LiBeF$$_{3}$$

Ono, Hideo; *

Journal of Nuclear Science and Technology, 27(1), p.45 - 48, 1990/01

no abstracts in English

Journal Articles

Radiation effect of aromatic lubricating oils

Nakanishi, Hiroshi*; Arakawa, Kazuo; Hayakawa, Naohiro; Machi, Sueo; Yagi, Tetsuya*

Nihon Genshiryoku Gakkai-Shi, 26(8), p.718 - 724, 1984/00

 Times Cited Count:1 Percentile:19.62(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Radiation Resistance of Aromatic Oils With Improving Pour Point

Arakawa, Kazuo; *; Hayakawa, Naohiro

JAERI-M 83-060, 29 Pages, 1983/04

JAERI-M-83-060.pdf:0.95MB

no abstracts in English

Journal Articles

Radiation effect of commercial lubricating oils

Nakanishi, Hiroshi*; Arakawa, Kazuo; Hayakawa, Naohiro; Machi, Sueo; Yagi, Tetsuya*

Nihon Genshiryoku Gakkai-Shi, 25(3), p.217 - 224, 1983/00

 Times Cited Count:1 Percentile:22.86(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Establishment of corresponding-state principle in molten fluoroberyllates and silicates and its application

Furukawa, Kazuo;

Trans.JIM, 19(19), p.553 - 561, 1978/00

no abstracts in English

Journal Articles

JAEA Reports

Physical Properties of Radiation Polymerized Polyethylene Slurry

; Yamaguchi, Koichi; ; ; *; Takehisa, Masaaki

JAERI-M 5477, 44 Pages, 1973/12

JAERI-M-5477.pdf:1.27MB

no abstracts in English

Oral presentation

Full-f gyrokinetic simulations of neoclassical toroidal viscosity in perturbed tokamaks

Matsuoka, Seikichi*; Idomura, Yasuhiro; Satake, Shinsuke*

no journal, , 

When non-axisymmetric magnetic perturbations are imposed in axisymmetric tokamaks, broken axisymmetry induces the neoclassical viscosity, and affects momentum transport and resulting plasma rotation profiles. In this work, we estimate the neoclassical toroidal viscosity using full-f gyrokinetic simulations, and verify calculation methods and obtained results. We discuss the parameter dependency of the neoclassical toroidal viscosity in the presence of small resonant magnetic perturbations, based on comparisons against analytic theories and neoclassical transport codes.

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