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Journal Articles

Measurement of void fraction distribution in a sphere-packed bed using X-ray imaging

Yamamoto, Seishiro*; Odaira, Naoya*; Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Imaizumi, Yuya; Matsuba, Kenichi; Kamiyama, Kenji

Konsoryu, 37(1), p.79 - 85, 2023/03

Journal Articles

Measurements of pressure drop and void fraction of air-water two-phase flow in a sphere-packed bed

Yamamoto, Seishiro*; Odaira, Naoya*; Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Imaizumi, Yuya; Matsuba, Kenichi; Kamiyama, Kenji

Proceedings of 12th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS12) (Internet), 4 Pages, 2022/10

Journal Articles

Two-phase flow structure in a particle bed packed in a confined channel

Ito, Daisuke*; Kurisaki, Tatsuya*; Ito, Kei*; Saito, Yasushi*; Imaizumi, Yuya; Matsuba, Kenichi; Kamiyama, Kenji

Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.6430 - 6439, 2019/08

In core disruptive accident of sodium-cooled fast reactor, cooling of residual fuel debris formed in the reactor core is one of important factors to achieve in-vessel retention of the fuel. To clarify the feasibility of the cooling which is called "in-place cooling", characteristics of gas-liquid two-phase flow in the debris bed must be well understood. Since the debris bed can be formed in a confined flow channel in the core, effect of the channel wall cannot be neglected. Thus, this study aims to clarify the effect of the wall on two-phase flow characteristics in the debris bed, which was simulated as a particle bed packed in a pipe. The pressure drop was measured and compared with results by previous models, and porosity and void fraction distributions were measured by X-ray radiography. Then, the pressure drop evaluation model was modified considering the wall effect, and the applicability of the models was discussed.

Journal Articles

Effect of porosity distribution on two-phase pressure drop in a packed bed

Kurisaki, Tatsuya*; Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Imaizumi, Yuya; Matsuba, Kenichi; Kamiyama, Kenji

Proceedings of 11th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-11) (Internet), 3 Pages, 2018/11

In the evaluation of the in-place cooling which is for the residual core materials in the severe accident of sodium-cooled fast reactors, pressure loss of two-phase flow in debris bed is one of the important factors. Although Lipinski model is already proposed for the pressure loss evaluation, the accuracy would decrease when the porosity is not homogeneous. Thus, experiment to measure the pressure loss in a packed bed of non-homogeneous porosity distribution was conducted, and the Lipinski model was modified dividing the cross section to evaluate the pressure loss in it. As a result, it was confirmed that agreement of the experimental values with the values by modified Lipinski model was better than that with the original Lipinski model.

Journal Articles

Development of space solar sheet with inverted triple-junction cells

Yamaguchi, Hiroshi*; Ijichi, Ryo*; Suzuki, Yoshiyuki*; Ooka, Sachiyo*; Shimada, Keiji*; Takahashi, Naoki*; Washio, Hidetoshi*; Nakamura, Kazuyo*; Takamoto, Tatsuya*; Imaizumi, Mitsuru*; et al.

Proceedings of 42nd IEEE Photovoltaic Specialists Conference (PVSC-42) (CD-ROM), p.2407 - 2411, 2015/06

JAEA Reports

Conceptual design of multipurpose compact research reactor; Annual report FY2010 (Joint research)

Imaizumi, Tomomi; Miyauchi, Masaru; Ito, Masayasu; Watahiki, Shunsuke; Nagata, Hiroshi; Hanakawa, Hiroki; Naka, Michihiro; Kawamata, Kazuo; Yamaura, Takayuki; Ide, Hiroshi; et al.

JAEA-Technology 2011-031, 123 Pages, 2012/01

JAEA-Technology-2011-031.pdf:16.08MB

The number of research reactors in the world is decreasing because of their aging. However, the planning to introduce the nuclear power plants is increasing in Asian countries. In these Asian countries, the key issue is the human resource development for operation and management of nuclear power plants after constructed them, and also the necessity of research reactor, which is used for lifetime extension of LWRs, progress of the science and technology, expansion of industry use, human resources training and so on, is increasing. From above backgrounds, the Neutron Irradiation and Testing Reactor Center began to discuss basic concept of a multipurpose low-power research reactor for education and training, etc. This design study is expected to contribute not only to design tool improvement and human resources development in the Neutron Irradiation and Testing Reactor Center but also to maintain and upgrade the technology on research reactors in nuclear power-related companies. This report treats the activities of the working group from July 2010 to June 2011 on the multipurpose low-power research reactor in the Neutron Irradiation and Testing Reactor Center and nuclear power-related companies.

Journal Articles

Controls over structural and electronic properties of epitaxial graphene on silicon using surface termination of 3C-SiC(111)/Si

Fukidome, Hirokazu*; Abe, Shunsuke*; Takahashi, Ryota*; Imaizumi, Kei*; Inomata, Shuya*; Handa, Hiroyuki*; Saito, Eiji*; Enta, Yoshiharu*; Yoshigoe, Akitaka; Teraoka, Yuden; et al.

Applied Physics Express, 4(11), p.115104_1 - 115104_3, 2011/11

 Times Cited Count:35 Percentile:77.75(Physics, Applied)

Journal Articles

Control of epitaxy of graphene by crystallographic orientation of a Si substrate toward device applications

Fukidome, Hirokazu*; Takahashi, Ryota*; Abe, Shunsuke*; Imaizumi, Kei*; Handa, Hiroyuki*; Kang, H. C.*; Karasawa, Hiromi*; Suemitsu, Tetsuya*; Otsuji, Taiichi*; Enta, Yoshiharu*; et al.

Journal of Materials Chemistry, 21(43), p.17242 - 17248, 2011/11

 Times Cited Count:28 Percentile:62.37(Chemistry, Physical)

Journal Articles

First flight demonstration of film-laminated InGaP/GaAs and CIGS thin-film solar cells by JAXA's small satellite in LEO

Morioka, Chiharu*; Shimazaki, Kazunori*; Kawakita, Shiro*; Imaizumi, Mitsuru*; Yamaguchi, Hiroshi*; Takamoto, Tatsuya*; Sato, Shinichiro; Oshima, Takeshi; Nakamura, Yosuke*; Hirako, Keiichi*; et al.

Progress in Photovoltaics; Research and Applications, 19(7), p.825 - 833, 2011/11

 Times Cited Count:26 Percentile:69.95(Energy & Fuels)

Journal Articles

Low-energy-electron-diffraction and X-ray-phototelectron-spectroscopy studies of graphitization of 3C-SiC(111) thin film on Si(111) substrate

Takahashi, Ryota*; Handa, Hiroyuki*; Abe, Shunsuke*; Imaizumi, Kei*; Fukidome, Hirokazu*; Yoshigoe, Akitaka; Teraoka, Yuden; Suemitsu, Maki*

Japanese Journal of Applied Physics, 50(7), p.070103_1 - 070103_6, 2011/07

 Times Cited Count:32 Percentile:74.62(Physics, Applied)

Journal Articles

Oxygen-induced reduction of the graphitization temperature of SiC surface

Imaizumi, Kei*; Handa, Hiroyuki*; Takahashi, Ryota*; Saito, Eiji*; Fukidome, Hirokazu*; Enta, Yoshiharu*; Teraoka, Yuden; Yoshigoe, Akitaka; Suemitsu, Maki*

Japanese Journal of Applied Physics, 50(7), p.070105_1 - 070105_6, 2011/07

 Times Cited Count:4 Percentile:18.66(Physics, Applied)

Oral presentation

Studies of epitaxial graphene formation using real-time synchrotron-radiation photoemission spectroscopy

Suemitsu, Maki*; Fukidome, Hirokazu*; Takahashi, Ryota*; Abe, Shunsuke*; Imaizumi, Kei*; Teraoka, Yuden; Yoshigoe, Akitaka

no journal, , 

no abstracts in English

Oral presentation

Development of an in-vessel inspection technology using remote imaging and spectroscopy, 2-2; Radiation resistance of optical fibers

Ito, Chikara; Naito, Hiroyuki; Ito, Hideaki; Imaizumi, Kazuyuki; Nagai, Akinori; Ito, Keisuke; Nishimura, Akihiko; Oba, Hironori; Wakaida, Ikuo; Sugiyama, Akira; et al.

no journal, , 

no abstracts in English

Oral presentation

Study on coolant behavior in damaged core of sodium-cooled fast reactor, 4; Evaluation of pressure drop through simulated debris bed in consideration of porosity distribution

Kurisaki, Tatsuya*; Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Imaizumi, Yuya; Matsuba, Kenichi; Kamiyama, Kenji

no journal, , 

The pressure loss of two-phase flow in debris bed is one of the important factor for coolability evaluation of the inplace-cooling for the residual core-materials in the severe accident of sodium-cooled fast reactors. Although Lipinski model is already proposed for the pressure loss evaluation, the accuracy would decrease when the porosity is not homogeneous. Thus, the evaluation method by dividing the cross section was developed for the two-phase flow in packed bed of non-homogenious porosity, and compared the calculated values with experimental data for the validation.

Oral presentation

Study on coolant behavior in damaged core of sodium-cooled fast reactor, 5; Effect of pipe and particle sizes on pressure drop in simulated debris bed

Ishiguro, Akinari*; Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Imaizumi, Yuya; Matsuba, Kenichi; Kamiyama, Kenji

no journal, , 

no abstracts in English

Oral presentation

Reduction of graphitization temperature of SiC surface by addition of oxygen

Imaizumi, Kei*; Takahashi, Ryota*; Miyamoto, Yu*; Handa, Hiroyuki*; Saito, Eiji*; Fukidome, Hirokazu*; Suemitsu, Maki*; Teraoka, Yuden; Yoshigoe, Akitaka

no journal, , 

As the graphene, 2D-crystal of a carbon atomic layer, has a large mobility of 300000 cm$$^{2}$$/V/s, it is expected as a candidate for the next generation electronic device material. As to the practical use of graphene, a graphene-on-silicon (GOS) technique in which graphene is formed by thermal annealling on an silicon substrate covered by an SiC thin film. Since the anneal temperature is high as 1523-1573 K for the graphene formation in the former techniques including the GOS technique, such a high temperature technique is not introduced indeed in silicon device fabrication processes. We noticed a temperature-pressure phase diagram reported by Yongwei Song et al.. We have succeeded to form a graphene film on the SiC surface at a lower temperature of 1273 K by adding a bit of oxygen gas in the anneal atmosphere.

Oral presentation

Study on coolant behavior in damaged core of sodium-cooled fast reactor, 6; Local void fraction measurement by using X-ray imaging in simulated debris bed

Yasugi, Noriaki*; Odaira, Naoya*; Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Imaizumi, Yuya; Matsuba, Kenichi; Kamiyama, Kenji

no journal, , 

no abstracts in English

Oral presentation

LEED and XPS observations of graphene-on-Si process

Takahashi, Ryota*; Miyamoto, Yu*; Handa, Hiroyuki*; Saito, Eiji*; Imaizumi, Kei*; Fukidome, Hirokazu*; Suemitsu, Maki*; Teraoka, Yuden; Yoshigoe, Akitaka

no journal, , 

In this study, a graphene-on-silicon process was observed by LEED and XPS to make clear mechanisms. LEED patterns of SiC(1$$times$$1) and Si(RT3$$times$$RT3)R30$$^{circ}$$ were observed on the 3C-SiC(111) surface formed on the Si(111) surface. After the thermal annealing process at 1523 K for 30 min, a LEED pattern of graphene(1$$times$$1) was also observed. The graphene(1$$times$$1) pattern was tilted to the SiC(1$$times$$1) pattern by 30 deg as expected. The graphene formation process of 3C-SiC(111) on the Si(111) is the same as that of a 6H-SiC(0001) substrate. Comparing a C1s photoemission peak before and after the annealling process, a Cis peak corresponding to an sp$$^{2}$$ hybrid orbital appeared and a peak due to SiC bulk decreased. These facts reveal that a surface state transformation from SiC(1$$times$$1)(bulk state) to graphene(1$$times$$1)(graphene state) takes place even in the graphene-on-silicon process on Si(111) surface as well as the graphene formation process on the 6H-SiC(0001) substrate.

Oral presentation

LEED and SR-XPS observations of graphitization on orientationally rotated epitaxial film of 3C-SiC(111)/Si(110)

Takahashi, Ryota*; Handa, Hiroyuki*; Abe, Shunsuke*; Inomata, Shuya*; Imaizumi, Kei*; Fukidome, Hirokazu*; Teraoka, Yuden; Yoshigoe, Akitaka; Kotsugi, Masato*; Okochi, Takuo*; et al.

no journal, , 

no abstracts in English

Oral presentation

LEED and SR-XPS observations of graphene formation processes on 3C-SiC(100)/Si(100) thin film

Inomata, Shuya*; Handa, Hiroyuki*; Abe, Shunsuke*; Takahashi, Ryota*; Imaizumi, Kei*; Fukidome, Hirokazu*; Teraoka, Yuden; Yoshigoe, Akitaka; Kotsugi, Masato*; Okochi, Takuo*; et al.

no journal, , 

no abstracts in English

39 (Records 1-20 displayed on this page)