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

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.

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.

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

https://doi.org/10.1039/c1jm12921j

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

https://doi.org/10.1143/JJAP.50.070103

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(11) and Si(RT3RT3)R30 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(11) was also observed. The graphene(11) pattern was tilted to the SiC(11) 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 hybrid orbital appeared and a peak due to SiC bulk decreased. These facts reveal that a surface state transformation from SiC(11)(bulk state) to graphene(11)(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.

Development of an in-vessel inspection technology using remote imaging and spectroscopy, 3-3; Transmission characteristics of a silica core fiber under high radiation

Naito, Hiroyuki; Ito, Chikara; Ito, Keisuke; Imaizumi, Kazuyuki; Ito, Hideaki; Nagai, Akinori

no journal, , 

no abstracts in English

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

Evaluation method of radiation irradiation to space solar cell for international standardization

Imaizumi, Mitsuru*; Saito, Masashi*; Sato, Shinichiro; Yasuda, Keisuke*

no journal, , 

no abstracts in English

Epitaxy of graphene on Si substrates toward three-dimensional graphene devices

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

no journal, , 

Graphene, two-dimensional network of sp carbon, is one of promising materials beyond CMOS, as described in the semiconductor roadmap. The major issue is a lack of reasonable process for epitaxial growth on substrates. In fact, current production methods, such as exfoliation from graphite and epitaxy on SiC single crystals, are not mass-productive. We are seeking the ways to develop graphene-on-silicon (3D-GOS) process to match recent trends of silicon technologies. One of key issues toward 3D-GOS is the formation of epitaxial graphene on main plane directions of silicon, such as (100), (110) and (111). In this article, large area epitaxy of graphene on Si(110), Si(100) and Si(111) is presented. The result must be a good news because it can open new and realistic ways to three-dimensionally fabricate graphene-based devices beyond CMOS.