High temperature gas-cooled reactors

Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.

High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02

https://doi.org/10.1016/C2018-0-05383-9

As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.

Surface effect on ion track formation in amorphous SiN films

Morita, Yosuke*; Nakajima, Kaoru*; Suzuki, Motofumi*; Narumi, Kazumasa; Saito, Yuichi; Ishikawa, Norito; Hojo, Kiichi; Tsujimoto, Masahiko*; Isoda, Shoji*; Kimura, Kenji*

Nuclear Instruments and Methods in Physics Research B, 315, p.142 - 145, 2013/11

https://doi.org/10.1016/j.nimb.2013.03.043

Direct observation of fine structure in ion tracks in amorphous SiN by TEM

Nakajima, Kaoru*; Morita, Yosuke*; Suzuki, Motofumi*; Narumi, Kazumasa; Saito, Yuichi; Ishikawa, Norito; Hojo, Kiichi; Tsujimoto, Masahiko*; Isoda, Shoji*; Kimura, Kenji*

Nuclear Instruments and Methods in Physics Research B, 291, p.12 - 16, 2012/11

https://doi.org/10.1016/j.nimb.2012.09.007

Thin films of amorphous SiN (thickness 20 nm) were irradiated with 120-720 keV C ions and observed using transmission electron microscopy (TEM). The ion track produced in an amorphous material was directly observed by TEM. For quantitative analysis, the ion tracks were also observed using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). The observed ion track consists of a low density core (radius 2.5 nm) and a high density shell (width 2.5 nm), which is very similar to the ion tracks in amorphous SiO irradiated with high energy heavy ions observed by small angle X-ray scattering (SAXS). Although the observed ion tracks may be affected by surface effects, the present result indicates that TEM and HAADF-STEM have potential to observe directly the fine structures of ion tracks in amorphous materials.

Development of SiC/SiC composite from precursor polymer by radiation application

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

IAEA-SM-365/7, p.35 - 40, 2003/09

no abstracts in English

Styrene grafted and sulfonated proton conducting membranes based on radiation-crosslinked polytetrafluoroethylene and their fuel cell applications

Yamaki, Tetsuya; Asano, Masaharu; Morita, Yosuke*; Suwa, Takeshi*; Yoshida, Masaru

Proceedings of 9th International Conference on Radiation Curing (RadTech Asia '03) (CD-ROM), 4 Pages, 2003/00

Proton exchange membranes were prepared by the radiation-induced grafting of styrene into crosslinked polytetrafluoroethylene (PTFE) films and subsequent sulfonation. The degree of grafting was controlled in the range of 7-75% by the crosslinking density of the PTFE matrix as well as the grafting conditions. The films at the grafting yield of 30% were found to give the ion exchange membranes with a homogeneous distribution of sulfonic acid groups. The resulting membranes showed a large ion exchange capacity reaching 2.9 meq g, which exceeded the performance of commercially-available perfluorosulfonic acid films such as Nafion. This will encourage the use of our ion exchange membranes in polymer electrolyte fuel cells.

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

https://doi.org/10.1023/A:1012549228826

A very fine silicon carbide (SiC) fiber with diameter of 6 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 5-10Pas. 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%.

Fine silicon carbide fibers synthesized from polycarbosilane-polyvinylsilane polymer blend using electron beam curing

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

Journal of Materials Science, 36(2), p.357 - 362, 2001/01

https://doi.org/10.1023/A:1004864126085

no abstracts in English

Fine silicon carbide fiber synthesized from a silicon-based polymer blend using radiation curing

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

High Temperature Ceramic Matrix Composites, p.35 - 40, 2001/00

Silicon carbide (SiC) fiber, which is one of the likeliest candidates as a reinforcement fiber of ceramic matrix composites (CMCs), is synthesized from polycarbosilane (PCS). The diameter of thus SiC fibers is 10-15 m. In order to fabricate CMCs with 3-dimensional complex shapes, it is important to develop a SiC fiber with diameter of less than 10 m, flexibility, and high strength. In order to improve the spinnability of precursor polymer, we have blended polyvinylsilane (PVS), which is a liquid polymer at room temperature, to PCS as a spinning additive. According to relationship between temperature and melt viscosity of the polymer blend, it was found that the polymer can be melt-spun at about 490K, 110K lower than PCS (about 600K), and that the spinnability of the polymer is improved by blending PVS. Fine polymer fiber was obtained from the polymer blend, and finally, very fine SiC fiber with the average diameter of 6 m was synthesized from the PCS-PVS polymer blend.

Application of electron beam curing for silicon carbide fiber synthesis from blend polymer of polycarbosilane and polyvinylsilane

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

Proceedings of International Symposium on Prospect for Application of Radiation towards the 21st Century, p.139 - 140, 2000/03

no abstracts in English

Radiation processing for PTFE composite reinforced with carbon fiber

*; Udagawa, Akira; Morita, Yosuke

Conference Proceeding RadTech Asia'99, p.507 - 512, 1999/08

no abstracts in English