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Journal Articles

Thermophysical properties of molten stainless steel containing 5mass%B$$_{4}$$C

Fukuyama, Hiroyuki*; Higashi, Hideo*; Yamano, Hidemasa

Nuclear Technology, 205(9), p.1154 - 1163, 2019/09

 Times Cited Count:2 Percentile:14.12(Nuclear Science & Technology)

An electromagnetic-levitation technique performed in a static magnetic field was used to measure the density, surface tension, normal spectral emissivity, heat capacity, and thermal conductivity of molten 316L stainless steel (SS316L) and SS316L that contained 5mass%B$$_{4}$$C. The addition of 5mass%B$$_{4}$$C to SS316L yielded reductions of 111 K, 6%, 19%, and 6% in the liquidus temperature, density, normal spectral emissivity, and thermal conductivity at the liquidus temperature of SS316L, respectively. The heat capacity increased by 5% with this addition. Although the 5mass%B$$_{4}$$C addition had no clear effect on the surface tension, sulfur dissolved in the SS316L resulted in a significant decrease in the surface tension.

Journal Articles

Melting behavior and thermal conductivity of solid sodium-concrete reaction product

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

Journal of Nuclear Science and Technology, 56(6), p.513 - 520, 2019/06

 Times Cited Count:1 Percentile:34.57(Nuclear Science & Technology)

This study revealed melting points and thermal conductivities of four samples generated by sodium-concrete reaction (SCR). We prepared the samples using two methods such as firing mixtures of sodium and grinded concrete powder, and sampling depositions after the SCR experiments. In the former, the mixing ratios were determined from the past experiment. The latter simulated the more realistic conditions such as the temperature history and the distribution of Na and concrete. The thermogravimetry-differential thermal analyzer (TG-DTA) measurement showed the melting points were 865-942$$^{circ}$$C, but those of the samples containing metallic Na couldn't be clarified. In the two more realistic samples, the compression moldings in a furnace were observed. The observation revealed the softening temperature was 800-840$$^{circ}$$C and the melting point was 840-850$$^{circ}$$C, which was 10-20$$^{circ}$$C lower than the TG-DTA results. The thermodynamics calculation of FactSage 7.2 revealed the temperature of the onset of melting was caused by melting of the some components such as Na$$_{2}$$SiO$$_{3}$$ and/or Na$$_{4}$$SiO$$_{4}$$. Moreover, the thermal conductivity was $$lambda$$=1-3W/m-K, which was comparable to xNa$$_{2}$$O-1-xSiO$$_{2}$$ (x=0.5, 0.33, 0.25), and those at 700$$^{circ}$$C were explained by the equation of $$NBO/T$$.

Journal Articles

The Effects of plutonium content and self-irradiation on thermal conductivity of mixed oxide fuel

Ikusawa, Yoshihisa; Morimoto, Kyoichi; Kato, Masato; Saito, Kosuke; Uno, Masayoshi*

Nuclear Technology, 205(3), p.474 - 485, 2019/03

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

This study evaluated the effects of plutonium content and self-irradiation on the thermal conductivity of mixed-oxide (MOX) fuel. Samples of UO$$_{2}$$ fuel and various MOX fuels were tested. The MOX fuels had a range of plutonium contents, and some samples were stored for 20 years. The thermal conductivity of these samples was determined from thermal diffusivity measurements taken via laser flash analysis. Although the thermal conductivity decreased with increasing plutonium content, this effect was slight. The effect of self-irradiation was investigated using the stored samples. The reduction in thermal conductivity caused by self-irradiation depended on the plutonium content, its isotopic composition, and storage time. The reduction in thermal conductivity over 20 years' storage can be predicted from the change of lattice parameter. In addition, the decrease in thermal conductivity caused by self-irradiation was recovered with heat treatment, and recovered almost completely at temperatures over 1200 K. From these evaluation results, we formulated an equation for thermal conductivity that is based on the classical phonon-transport model. This equation can predict the thermal conductivity of MOX fuel thermal conductivity by accounting for the influences of plutonium content and self-irradiation.

Journal Articles

Thermal conductivity of U-20 wt.%Pu-2 wt.%Am-10 wt.%Zr alloy

Nishi, Tsuyoshi; Nakajima, Kunihisa; Takano, Masahide; Kurata, Masaki; Arita, Yuji*

Journal of Nuclear Materials, 464, p.270 - 274, 2015/09

 Times Cited Count:2 Percentile:84.76(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Thermal property measurements on Li$$_{2}$$TiO$$_{3}$$ added with TiO$$_{2}$$

Hoshino, Tsuyoshi; Kobayashi, Takeshi*; Nashimoto, Makoto*; Kawamura, Hiroshi; Dokiya, Masayuki*; Terai, Takayuki*; Yamawaki, Michio*; Takahashi, Yoichi*

JAERI-Conf 2004-012, p.140 - 147, 2004/07

no abstracts in English

Journal Articles

High-temperature thermophysical property measurements on non-stoichiometric composition of Li$$_{2}$$TiO$$_{3}$$

Hoshino, Tsuyoshi; Kobayashi, Takeshi*; Nashimoto, Makoto*; Kawamura, Hiroshi; Terai, Takayuki*; Yamawaki, Michio*; Takahashi, Yoichi*

Journal of the Ceramic Society of Japan, Supplement, Vol.112, No.1 (CD-ROM), p.S354 - S357, 2004/05

no abstracts in English

Journal Articles

Thermal conductivity of neutron irradiated Be$$_{12}$$Ti

Uchida, Munenori*; Ishitsuka, Etsuo; Kawamura, Hiroshi

Fusion Engineering and Design, 69(1-4), p.499 - 503, 2003/09

 Times Cited Count:16 Percentile:24.72

no abstracts in English

Journal Articles

Effective thermal conductivity of a Li$$_{2}$$TiO$$_{3}$$ pebble bed for a demo blanket

Hatano, Toshihisa; Enoeda, Mikio; Suzuki, Satoshi; Kosaku, Yasuo; Akiba, Masato

Fusion Science and Technology, 44(1), p.94 - 98, 2003/07

 Times Cited Count:17 Percentile:23.12(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Study on effect of effective thermal conductivities on melting characteristics of latent heat storage capsules

Shiina, Yasuaki; Inagaki, Terumi*

Nippon Kikai Gakkai Rombunshu, B, 69(681), p.1233 - 1241, 2003/05

In order to reduce phase change time in latent heat technology, improvement of effective thermal conductivity of heat storage unit would be one of the techniques. Effect of effective thermal conductivity on melting time are studied analytically of circular composite heat storage capsules made by immersing phase change materials (PCM) into porous metals. Numerical and approximate analysis were made with the consideration of uniform and non-uniform heat transfer coefficients around the cylindrical surface. Four PCMs (H$$_{2}$$O,Octadecane, Li$$_{2}$$CO$$_{3}$$, NaCl) and three metals (copper, aluminum and carbon steel) were selected specific materials. Porosity of the metals were restricted larger than 0.9 in order to lessen decrease in latent heat. Results show that reduction in melting time was obtained for the above PCMs, especially for low conductivity PCMs. Melting time obtained by approximate analysis agrees well with numerical analysis. High Nusselt number and high thermal conductivity of heat transfer fluid would be more effective to reduce phase change time.

Journal Articles

Effect of porous medium on heat transfer and flow in a circular tube

Uemura, Takuya*; Takeda, Tetsuaki; Ichimiya, Koichi*

Nippon Kikai Gakkai Yamanashi Koenkai Koen Rombunshu (020-4), p.49 - 50, 2002/10

A heat transfer experiment was performed using a horizontal circular tube to obtain the heat transfer and fluid flow characteristics in the tube inserted copper wire. From the results obtained in this experiment, it was found that an amount of heat removal in the tube with copper wire inserts increased about 20% comparing with a tube having a smooth wall. A heat transfer coefficient of the tube inserted copper wire also increased 30% to 50% under the constant pumping power condition.

Journal Articles

Thermal properties of pellet

Nakamura, Jinichi

Saishin Kaku Nenryo Kogaku; Kodoka No Genjo To Tembo, p.93 - 98, 2001/06

no abstracts in English

Journal Articles

Computer code analysis on fuel rod behavior

Suzuki, Motoe

Saishin Kaku Nenryo Kogaku; Kodoka No Genjo To Tembo, p.131 - 140, 2001/06

no abstracts in English

JAEA Reports

CompalisonoFnlermohydraulicCharacteristicsintheuseofvariousCoolants

; ; *; Yamaguchi, Akira

JNC-TN9400 2000-109, 96 Pages, 2000/11

JNC-TN9400-2000-109.pdf:9.56MB

Numerical calculations were carried out for a free surface sloshing, a thermal stratification, a thermal striping, and a natural convection as key phenomena of in-vessel thermohydraulics in future fast reactor systems with various fluids as coolants. This numerical work was initiaied based on a recognition that the fundamental characteristics of the phenomena have been unsolved quantitatively in the use of various coolants. From the analysis for the phenomena, the following results were obtained. [Free Surface Sloshing phenomena] (1)Ther is no remarkable difference betweeen liquid sodium and luquid Pb-Bi in characteristics of internal flows and free surface charatristics based on Fr number. (2)the AQUA-VOF code has a potentiall enough to evaluate gas entrainment behavior from the free surface including the internal flow characteristics. [thermal Stratification Phenomena] (1)On-set position of thermal entainment process due to dynamic vortex flows was moved to downstream direction with decreasing of Ri number. 0n the other hand, the position in the case of C0$$_{2}$$ gas was shifted to upstream side with decreasing of Ri number. (2)Destruction speed of the thermal stratyification interface was dependent on thermal diffusivity as fluid properties. therefor it was concluded that an elimination method is necessary for the interface generated in C0$$_{2}$$ gas. [thermal Striping Phenomena] (1)Large amplitudes of fluid temperature fluctuations was reached to down stream area in the use of CO$$_{2}$$ gas, due to larger fluid viscosity and smaller thermal diffusivity, compared with liquid sodium and liquid Pb-Bi cases. (2)To simulate thermal striping conditions such as amplitude and frequency of the fluid temperature fluctuations, it isnecessary for coincidences of Re number for the amplitude and of velocity value for the frequency, in various coolants. [Natural Convection Phenomena] (1)Fundamental behavior of the natural convection in various coolant follows buoyant jet ....

JAEA Reports

A study on properties of uranium oxide using band theory

Tejima, Shogo

JNC-TN8400 2000-029, 54 Pages, 2000/10

JNC-TN8400-2000-029.pdf:1.32MB

This report describes the study done by the author as a postdoctoral research associate at Japan Nuclear Cycle Development Institute. This report is divided into three parts: construction of a relativistic band calculation formalism based on the density functional theory, using this method, investigation of the electrical properties for ferromagnetic UGe$$_{2}$$ and antiferromagnetic UO$$_{2}$$. (1)A relativistic band calculation (RBC) method. Band calculations for the s, p, and d electric structure have been developed well in the practical application and theoretical study. But band calculation method treating magnetic 5f electrons as actinide compounds are complicated and needed relativistic approach, so it is behind with the study of the 5f system. In this study we construct the relativistic band calculationformalism valid for magnetic 5f electrons. (2)Electric properties of UGe$$_{2}$$. The actinide compounds UGe$$_{2}$$ is ferromagnetic, so the theoretical analysis is not well yet. The electric structure and fermi surface of UGe$$_{2}$$ are analyzed using the RBC. The theoretical results show that UGe$$_{2}$$ is heavy electron with the 5f character and are agreement with experimental one. (3)Electric structure of nuclear fuel UO$$_{2}$$. It is important to understand the mechanism of the thermal conductivity of nuclear fuel as antiferromagnetic UO$$_{2}$$. The UO$$_{2}$$ band calculation reflecting the thermal properties, into account of relativistic effect, have not done yes. So using the RBC the detailed electric structure of UO$$_{2}$$ are obtained.

JAEA Reports

The evaluation of material base standard of ODS ferritic stainless steel core component for fast breeder reactors

Mizuta, Shunji; ;

JNC-TN9400 2000-048, 28 Pages, 2000/04

JNC-TN9400-2000-048.pdf:0.64MB

ODS (Oxide Dispersion Strengthened) ferritic-martainsitic steels are one of the most prospective cladding materials for advanced fast breeder reactors, since they are expected to have excellent swelling resistance and superior high temperature strength due to the finely distributed stable oxide particles(Y$$_{2}$$O$$_{3}$$). Properties and the tentative strength equations for ODS ferritic-martainsitic were proposed on the basis of the latest data to apply to the feasibility study of the sodium coolant MOX fuel plant. The items of equations are follows. (1)creep rupture strength (2)correction factor of creep rupture strength (in Na and in reactor) (3)outer surface eorrosion (Na) (4)inner surface corrosion (in MOX fuel pin) (5)thermal conductivity

JAEA Reports

None

Koshizuka, Seiichi*; *; Okano, Yasushi; *; Yamaguchi, Akira

JNC-TY9400 2000-012, 91 Pages, 2000/03

JNC-TY9400-2000-012.pdf:2.82MB

no abstracts in English

JAEA Reports

None

Yamanaka, Shinsuke*; Uno, Masayoshi*; Kurosaki, Ken*; ; Namekawa, Takashi

JNC-TY9400 2000-011, 41 Pages, 2000/03

JNC-TY9400-2000-011.pdf:1.28MB

no abstracts in English

JAEA Reports

None

Yamanaka, Shinsuke*; Abe, Kazuyuki

JNC-TY9400 2000-004, 78 Pages, 2000/03

JNC-TY9400-2000-004.pdf:2.39MB

no abstracts in English

JAEA Reports

Current status and future plan for thermaI striping investigations at JNC

; kasahara, Naoto; ; ; Kamide, Hideki

JNC-TN9400 2000-010, 168 Pages, 2000/02

JNC-TN9400-2000-010.pdf:8.78MB

Thermal striping is significant issue of the structural integrity, where the hot and cold fluids give high cycle fatigue to the structure through the thermal stress resulted from the time change of temperatur distibution in the structure. In the sodium cooled fast reactor, temperature change in fluid easily transfers to the structure because of the high thermal conductivity of the sodium. It means that we have to take care of thermal striping, The thermal striping is complex phenomena between the fluid and structure engineering fields. The investigations of thermal striping are not enough to evaluate the integrity directly. That is the fluctuation intensity at the structure surface is assumed to be temperature difference between source fluids (upstream to the mixing region) as the maximum value in the design. 0therwise, the design conditions are defined by using a mockup experiment and large margin of temperature fluctuation intensity. Furthermore, such evaluation manners have not yet been considered as a design rule. Transfer mechanism of temperature fluctuation from fluid to structure has been investigated by the authors on the view points of the fluid and structure. Attenuation of temperature fluctuation was recognized as a dominant factor of thermal fatigue. We have devdoped a numerical analysis system which can evaluate thermal fatigue and crack growth with consideration of the attenuation of temperature fluctuation in fluid, heat transfer, and structure. This system was applied to a real reactor and the applicability was confirmed. Further verification is planned to generalize the system. For the higher cost performance of the fast reactor, an evaluation rule is needed, which can estimate thermal loading with attenuation and can be applied to the design. An idea of the rule is proposed here. Two methods should be prepared; one is a precise evaluation method where mechanism of attenuation is modeled, and the other is simple evaluation method where ...

JAEA Reports

Measurements of thermal properties of buffer materials; Measurement of physical properties of buffer materials and improvement of measuring method

*

JNC-TJ8400 2000-017, 74 Pages, 2000/02

JNC-TJ8400-2000-017.pdf:1.71MB

The report concerns the improvement of the method measuring thermal conductivity of buffer materials using a thermistor probe and the measurement of thermal conductivity of compacted bentonites and mixtures of bentonite and silica sand using the proposed method measuring thermophysical properties. The method measuring thermal conductivity is improved in accuracy and the apparatus is improved so as to measure easily with more short time. The calculated values of the conventional correlations predicting thermal conductivity of bentonite and mixture were compared with the exising and present data of thermal conductivity of bentonites and mixtures. The correlation proposed by Sakashita and Kumada can predict the best fitted values with the data of the bentonites and Fricke and Bruggeman correlations are fitted with the data for the mixtures with practical accuracy.

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