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Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors; Project overview and progress until JFY2022

Yamano, Hidemasa; Takai, Toshihide; Emura, Yuki; Fukuyama, Hiroyuki*; Nishi, Tsuyoshi*; Morita, Koji*; Nakamura, Kinya*; Pellegrini, M.*

Nihon Kikai Gakkai 2023-Nendo Nenji Taikai Koen Rombunshu (Internet), 5 Pages, 2023/09

A research project has been conducting thermophysical property measurement of a eutectic melt, eutectic melting reaction and relocation experiments, eutectic reaction mechanism investigation, and physical model development on the eutectic melting reaction for reactor application analysis in order to simulate the eutectic melting reaction and relocation behavior of boron carbide as a control rod material and stainless steel during a core disruptive accident in an advanced sodium-cooled fast reactor designed in Japan. This paper describes the project overview and progress until JFY2022.

Journal Articles

Investigation of adsorption mechanism of Mo(VI) by baker's yeast and applicability to the uranium liquid waste treatment process

Arai, Yoichi; Hasegawa, Kenta; Watanabe, So; Watanabe, Masayuki; Minowa, Kazuki*; Matsuura, Haruaki*; Hagura, Naoto*; Katsuki, Kenta*; Arai, Tsuyoshi*; Konishi, Yasuhiro*

Journal of Radioanalytical and Nuclear Chemistry, 9 Pages, 2023/00

Journal Articles

In-operando lithium-ion transport tracking in an all-solid-state battery

Kobayashi, Takane*; Onishi, Tsuyoshi*; Osawa, Takahito; Pratt, A.*; Tear, S.*; Shimoda, Susumu*; Baba, Hidetada*; Laitinen, M.*; Sajavaara, T.*

Small, 18(46), p.2204455_1 - 2204455_9, 2022/11

 Times Cited Count:1 Percentile:37.1(Chemistry, Multidisciplinary)

An all-solid-state battery is a secondary battery that is charged and discharged by the transport of lithium ions between positive and negative electrodes. To fully realize the significant benefits of this battery technology, for example, higher energy densities, faster charging times, safer operation, it will be essential to understand how lithium ions are transported and distributed in the battery during operation. However, as the third lightest element, methods for quantitatively analyzing lithium during operation of an all-solid-state device are limited such that real time tracking of lithium transport has not yet been demonstrated. Here, we report that the transport of lithium ions in an all-solid-state half-cell was quantitatively tracked in near real time by utilizing a thermal neutron-induced nuclear reaction, utilizing lithium-6 as a tracer, and utilizing a high-intensity thermal neutron source. Furthermore, it is also mentioned that the migration mechanism and migration region of lithium ions in the solid electrolyte used could be determined by tracking the transport of lithium ions. From these results, it can be said that the development of all-solid-state batteries has entered a phase where further advances could be carried out while understanding the transport of lithium ions in the batteries. As a result, the research and development of all-solid-state batteries would be further accelerated.

Journal Articles

Measurement of density and viscosity for molten salts

Sato, Rika*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Hayashi, Hirokazu; Sugawara, Takanori; Nishihara, Kenji

Dai-43-Kai Nihon Netsu Bussei Shimpojiumu Koen Rombunshu (CD-ROM), 3 Pages, 2022/10

no abstracts in English

Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview and progress until 2020

Yamano, Hidemasa; Takai, Toshihide; Emura, Yuki; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Morita, Koji*; Nakamura, Kinya*; Fukai, Hirofumi*; et al.

Proceedings of 13th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-13) (Internet), 12 Pages, 2022/09

This paper describes the project overview and progress of experimental and analytical studies conducted until 2020. Specific results in this paper are the measurement of the eutectic reaction rates and the validation of physical model describing the eutectic reaction in the analysis code through the numerical analysis of the B$$_{4}$$C-SS eutectic reaction rate experiments in which a B$$_{4}$$C pellet was placed in a SS crucible.

Journal Articles

Viscosity measurements of molten metal using an improved oscillating crucible method

Sato, Rika*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Yamano, Hidemasa

International Journal of Thermophysics, 43(6), p.85_1 - 85_15, 2022/06

 Times Cited Count:0 Percentile:0.01(Thermodynamics)

In this study, we developed a simple viscosity measurement method based on the principle of least squares to derive the period and logarithmic decrement of oscillation. To confirm the reproducibility of the proposed method, the viscosity of molten nickel was measured and found to be in good agreement with those reported in the literature. The measurement error was less than $$pm$$3%. Further, the experimental data showed good reproducibility, and the measurements were obtained with high accuracies using the proposed method.

Journal Articles

Evaluation of thermal diffusivity of uniaxial CFRP sheet by offset periodic laser heating method

Nagata, Sho*; Miyake, Shugo*; Igarashi, Takahiro; Ota, Hiromichi*; Nishi, Tsuyoshi*

Jikken Rikigaku, 22(2), p.105 - 111, 2022/06

Thermal easy axis and thermal diffusivity of uniaxial carbon fiber-reinforced plastic sheets were determined by a offset periodic laser heating method, and investigated relationship between the thermal easy axis and fiber orientation with different thickness of CFRP sheet specimen, experimentally. It was clarified that the orientation of the thermal easy axis spreads in the in-plane direction with the sheet thickness deceases. Then, thermal diffusivity of CFRP specimens in the out-of-plane and in-plane direction were measured by two method: a variable-frequency method and a variable-displacement method, respectively. In the results of the out-of-plane directions, thermal diffusivity almost consistent with the carbon fiber direction were obtained. In contrast, the in-plane directions of those were exhibited unexpected value. Moreover, thermal diffusivity determination by offset periodic heating method was carried out. Finally, it is found that the thermal diffusivity considering the thermal easy axis with fiber angle was different characteristics from the in-plane direction measurement.

Journal Articles

Viscosity measurements of Molten casting steels for high temperature using an oscillating crucible viscometer

Takatsuka, Yuriko*; Matsumoto, Saori*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Hori, Ayumi*; Hayashi, Kiichiro*; Yamano, Hidemasa

Jikken Rikigaku, 22(2), p.117 - 119, 2022/06

This study clarified the effect of the viscosities of molten casting steels for high temperature by measuring them using the oscillating crucible method. The casting steels for high temperature samples used for viscosity measurements contained 0, 10, 20, 30, 40, and 50 mass% Ni. Viscosities were evaluated using Roscoe's equation and measured in the temperature range of 1693-1803 K.

Journal Articles

Viscosity measurements of molten Ni-based superalloys by the oscillating crucible method

Matsumoto, Saori*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Hori, Ayumi*; Hayashi, Kiichiro*; Yamano, Hidemasa

Jikken Rikigaku, 22(2), p.112 - 116, 2022/06

In this study, the viscosity of the molten Ni-based superalloys were measured by the oscillating crucible method. When the logarithm of the viscosity was plotted against the inverse temperature (Arrhenius-type plot), all alloys showed a good Arrhenius-type linearity over the temperature range investigated. It was also found that the viscosities of molten Ni-based superalloys decreased with increasing the Co contents.

Journal Articles

Study on the thermal behavior of Carbon-Fiber-Reinforced-Plastic (CFRP) sheet using a periodic heating method

Nagata, Sho*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Igarashi, Takahiro; Miyake, Shugo*

Proceedings of 34th International Microprocesses and Nanotechnology Conference (MNC 2021) (CD-ROM), 2 Pages, 2021/10

Due to the increasing heat generation density of electronic devices, unidirectional Carbon-fiber-reinforced Plastic (CFRP) has gained interest as a heat-dissipating material owing to its high thermal conductivity, high anisotropy, and high strength. If CFRPs can be used to conduct heat in the desired direction of dissipation, more efficient thermal designs are possible. To control heat propagation, it is necessary to understand the heat propagation behavior within CFRPs at each fiber angle by determining the direction of heat propagation, referred to as thermal orientation. We previously demonstrated an approach for determining the thermal orientation of CFRPs using a periodic heating method, wherein the heat propagation in CFRPs was classified into two directions: the direction of the carbon fiber direction and the direction of the fiber-matrix interface. It has been suggested that the fiber-matrix interface has a significant effect on the heat propagation of CFRPs, which increases with the increase in CFRP thickness. However, the effect of CFRP thickness on thermal orientation is yet unknown. In the current study, we investigated the effect of the fiber-matrix interface on thermal orientation using the periodic heating method for CFRPs with varying thicknesses.

Journal Articles

Viscosities of molten B$$_{4}$$C-stainless steel alloys

Nishi, Tsuyoshi*; Sato, Rika*; Ota, Hiromichi*; Kokubo, Hiroki*; Yamano, Hidemasa

Journal of Nuclear Materials, 552, p.153002_1 - 153002_7, 2021/08

 Times Cited Count:2 Percentile:32.89(Materials Science, Multidisciplinary)

Determining high precision viscosities of molten B$$_{4}$$C-stainless steel (B$$_{4}$$C-SS) alloys is essential for the core disruptive accident analyses of sodium-cooled fast reactors and for analysis of severe accidents in boiling water reactors (BWR) as appeared in Fukushima Daiichi. However, there are no data on the high precision viscosities of molten B$$_{4}$$C-SS alloys due to experimental difficulties. In this study, the viscosities of molten SS (Type 316L), 2.5mass%B$$_{4}$$C-SS, 5.0mass%B$$_{4}$$C-SS, and 7.0mass%B$$_{4}$$C-SS alloys were measured using the oscillating crucible method in temperature ranges of 1693-1793 K, 1613-1793 K, 1613-1793 K, and 1713-1793 K, respectively. The viscosity was observed to increase as the B$$_{4}$$C concentration increased from 0 to 7.0 mass%. Using the experimental data of the molten 2.5mass%B$$_{4}$$C-SS and 5.0mass%B$$_{4}$$C-SS and 7.0mass%B$$_{4}$$C-SS in the temperature range of 1713-1793 K, the equation for the viscosity of molten B$$_{4}$$C-SS alloys was determined, and the measurement error of the viscosity of molten B$$_{4}$$C-SS alloys is less than $$pm$$8%.

Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview and progress until 2019

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 11 Pages, 2021/08

One of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors is eutectic reactions between boron carbide (B$$_{4}$$C) and stainless steel (SS) as well as its relocation. Such behaviors have never been simulated in CDA numerical analyses in the past, therefore it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study focuses on B$$_{4}$$C-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in a range from solid to liquid state. The physical model is developed for a CDA computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies conducted until 2019. Specific results in this paper are the validation of physical model describing B$$_{4}$$C-SS eutectic reaction in the CDA analysis code, SIMMER-III, through the numerical analysis of the B$$_{4}$$C-SS eutectic melting experiments in which a B$$_{4}$$C block was placed in a SS pool.

Journal Articles

Thermodynamic and thermophysical properties of the actinide nitrides

Uno, Masayoshi*; Nishi, Tsuyoshi*; Takano, Masahide

Comprehensive Nuclear Materials, 2nd Edition, Vol.7, p.202 - 231, 2020/08

On the thermodynamic and thermophysical properties of the actinide nitrides in Comprehensive Nuclear Materials published by Elsevier as the first edition in 2012, we have revised them by adding some brand-new data. The main topics added are the solid solubility of the actinide nitrides into the zirconium nitride matrix for transmutation fuel, the lattice expansion of actinide nitrides induced by self-irradiation damage, the influence of defects accumulation on thermal conductivity, and the thermal expansion in curium nitride lattice.

Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview and progress until 2018

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 10 Pages, 2020/08

One of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors is eutectic reactions between boron carbide (B$$_{4}$$C) and stainless steel (SS) as well as its relocation. Such behaviors have never been simulated in CDA numerical analyses in the past, therefore it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study focuses on B$$_{4}$$C-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in a range from solid to liquid state. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies conducted until 2018. Specific results in this paper are boron concentration distributions of solidified B$$_{4}$$C-SS eutectic sample in the eutectic melting experiments, which would be used for the validation of the eutectic physical model implemented into the computer code.

Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.418 - 427, 2019/09

Eutectic reactions between boron carbide (B$$_{4}$$C) and stainless steel (SS) as well as its relocation are one of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors. Since such behaviors have never been simulated in CDA numerical analyses, it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study is focusing on B$$_{4}$$C-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in the range from solid to liquid state. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies by 2017. Specific results in this paper is boron concentration distributions of solidified B$$_{4}$$C-SS eutectic sample in the eutectic melting experiments, which would be used for the validation of the eutectic physical model implemented into the computer code.

Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 4; Effect of B$$_{4}$$C addition on viscosity of austenitic stainless steel in liquid state

Ota, Hiromichi*; Kokubo, Hiroki*; Nishi, Tsuyoshi*; Yamano, Hidemasa

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.858 - 860, 2019/09

A viscosity measurement apparatus has been developed. It is known that the measurement of the viscosity of molten alloy at elevated temperatures is difficult due to the difficulty of handling for low viscosity fluids such as the stainless steel (SS)+B$$_{4}$$C alloy. In this study, the viscosities of the molten nickel (Ni) and stainless steel (SS) were measured by the oscillating crucible method to confirm the performance of the viscosity measurement apparatus as a first step. This method is suitable for high temperature molten alloys. A crucible containing molten metal is suspended, and a rotational oscillation is given to the crucible electromagnetically. The oscillation was damped by the friction of molten metal. The viscosity is determined from the period of oscillation and the logarithmic decrement. The crucible was connected to a mirror block and an inertia disk made of aluminum, and whole of them was suspended by a wire made of platinum-13% rhodium alloy. A laser light is irradiated to the mirror. The reflection light is detected by the photo-detectors, and then, the logarithmic decrement of molten metal is determined. The viscosities of molten nickel and SS melts were measured up to 1823 K. In these results, the measured viscosity values of molten Ni and SS were close to those of the literature values of molten Ni and SS. By the equipment, the viscosity of molten SS+B$$_{4}$$C alloys are measured. The B$$_{4}$$C concentration dependence of the viscosity of molten SS+B$$_{4}$$C alloys is to be clarified.

Journal Articles

Viscosity measurement of nickel and stainless steel aiming at systematic viscosity measurement for molten mixture of stainless steel and boron-carbide

Kokubo, Hiroki*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Yamano, Hidemasa

Nihon Kinzoku Gakkai-Shi, 82(10), p.400 - 402, 2018/09

 Times Cited Count:6 Percentile:33.02(Metallurgy & Metallurgical Engineering)

It is important to obtain the viscosity of a mixed alloy consisting of molten stainless steel and boron-carbide (SUS316L + B$$_{4}$$C alloy) for the improvement of severe accident assessment methodology for sodium-cooled fast reactors. In this study, the viscosities of the molten nickel (Ni) and stainless steel (SUS316L) were measured by the oscillating crucible method to confirm the performance of the viscosity measurement apparatus as a first step. The viscosities of molten Ni and SUS316L melts were measured up to 1823 K. It was found that the measured viscosity values of molten Ni and SUS316L were estimated from the deviation of the experimental data, were $$pm$$4% and $$pm$$3%, respectively. It was also found that those of molten Ni and SUS316L were close to those of the literature values of molten Ni and similar composite stainless steels. Moreover, we tentatively measured the viscosity of molten SUS316L-5 mass%B$$_{4}$$C alloy. The fitted results of the viscosity for molten Ni and SUS316L were obtained.

Journal Articles

Quantum phase transitions driven by rhombic-type single-ion anisotropy in the $$S$$=1 Haldane chain

Tzeng, Y.-C.*; Onishi, Hiroaki; Okubo, Tsuyoshi*; Kao, Y.-J.*

Physical Review B, 96(6), p.060404_1 - 060404_7, 2017/08

 Times Cited Count:20 Percentile:73.11(Materials Science, Multidisciplinary)

Journal Articles

Cesium adsorption/desorption behavior of clay minerals considering actual contamination conditions in Fukushima

Mukai, Hiroki*; Hirose, Atsushi*; Motai, Satoko*; Kikuchi, Ryosuke*; Tanoi, Keitaro*; Nakanishi, Tomoko*; Yaita, Tsuyoshi; Kogure, Toshihiro*

Scientific Reports (Internet), 6, p.21543_1 - 21543_7, 2016/02

 Times Cited Count:126 Percentile:96.66(Multidisciplinary Sciences)

Journal Articles

Fundamental experiments on phase stabilities of Fe-B-C ternary systems

Sudo, Ayako; Nishi, Tsuyoshi; Shirasu, Noriko; Takano, Masahide; Kurata, Masaki

Journal of Nuclear Science and Technology, 52(10), p.1308 - 1312, 2015/10

 Times Cited Count:13 Percentile:73.52(Nuclear Science & Technology)

For understanding the control blade degradation mechanism of BWR, the thermodynamic database for the fuel assembly materials is a useful tool. Although iron, boron, and carbon ternary system is a dominant phase diagram, phase relation data is not sufficient for the region in which the boron and carbon compositions are richer than the eutectic composition. The phase relations of three samples were analyzed by X-ray diffraction, scanning electron microscope and energy dispersed X-ray spectrometry. The results indicate that Fe$$_{3}$$(B,C) phase only exists in the intermediate region at 1273 K and that the solidus temperature widely maintains at about 1400 K for all three samples, which are different from the calculated data using previous thermodynamic database. The difference might be originated from the over-estimations of the interaction parameter between boron and carbon in Fe$$_{3}$$(B,C).

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