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Usuda, Shigekazu; Yasuda, Kenichiro; Kokubu, Yoko; Esaka, Fumitaka; Lee, C. G.; Magara, Masaaki; Sakurai, Satoshi; Watanabe, Kazuo; Hirayama, Fumio; Fukuyama, Hiroyasu; et al.
International Journal of Environmental Analytical Chemistry, 86(9), p.663 - 675, 2006/08
Times Cited Count：14 Percentile：38.86(Chemistry, Analytical)The IAEA introduced the environmental sample analysis method, as a powerful tool to detect undeclared nuclear activities, into strengthened safeguards system. The principle of the method is that nuclear signatures can be evidenced if trace amount of nuclear materials in environmental samples taken from inside and outside of nuclear facilities are accurately analyzed. Currently, isotope ratios of uranium and plutonium in "swipe" samples are measured, which are collected in nuclear facilities. In future, the subject of environmental sample analysis will expand to soil, sediment, vegetation, water and airborne dust taken from outside of the nuclear facilities. If physical and chemical form of the nuclear materials is identified, we may estimate their origin, treatment process and migration behavior. This paper deals with the developed analytical techniques for the safeguards environmental samples, the current R&D on techniques related to estimation of the physical and chemical form, and possible analytical methodologies applicable to ultra-trace amounts of nuclear materials.
Sakurai, Satoshi; Magara, Masaaki; Usuda, Shigekazu; Watanabe, Kazuo; Esaka, Fumitaka; Hirayama, Fumio; Lee, C. G.; Yasuda, Kenichiro; Kono, Nobuaki; Inagawa, Jun; et al.
Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10
no abstracts in English
Magara, Masaaki; Usuda, Shigekazu; Sakurai, Satoshi; Watanabe, Kazuo; Esaka, Fumitaka; Hirayama, Fumio; Lee, C. G.; Yasuda, Kenichiro; Kono, Nobuaki; Inagawa, Jun; et al.
Dai-26-Kai Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Nenji Taikai Rombunshu, p.157 - 164, 2005/00
JAERI has conducted the analysis of domestic and the IAEA samples. JAERI is developing the analytical techniques to improve the analytical ability for the safeguards environmental samples. For bulk analysis, study is focused on the improvement of reliability of isotope ratio measurements by ICP-MS. New chemical separation techniques are under development and a desolvation module is introduced to reduce the polyatomic interferences. In particle analysis, the sample preparation procedure for SIMS method is modified to measure the 
U/
U and 
U/U ratios for individual particles. We are also developing fission track-TIMS method to measure uranium isotope ratios in particles of sub-micrometer size. A screening instrument of X-ray fluorescent analysis is equipped to measure elemental distribution on a swipe surface.
Magara, Masaaki; Usuda, Shigekazu; Sakurai, Satoshi; Watanabe, Kazuo; Esaka, Fumitaka; Hirayama, Fumio; Lee, C. G.; Yasuda, Kenichiro; Kono, Nobuaki; Inagawa, Jun; et al.
Proceedings of INMM 46th Annual Meeting (CD-ROM), 8 Pages, 2005/00
JAERI has been developing analytical techniques for ultra-trace amounts of nuclear materials in the environmental samples in order to contribute to the strengthened safeguards system. Development of essential techniques for bulk and particle analysis of the environmental swipe sample has been established as an ultra-trace analytical method of uranium and plutonium. In January 2003, JAERI was qualified as a member of the IAEA network analytical laboratories for environmental samples. Since then, JAERI has conducted the analysis of domestic and the IAEA samples. From Japanese fiscal year 2003, the second phase of the project was started for the development of advanced techniques, such as analyzing minor actinides and fission products as well as uranium and plutonium, particle analysis using fission-track technique, more efficient particle analysis using ICP-TOFMS and screening by X-ray fluorescent analysis. This paper deals with the progress in the development of the new techniques, applications and future perspective.
Ikeda, Takashi; Chai, G.*; Hou, Z.*; Terakura, Kiyoyuki*
no journal, ,
no abstracts in English
Ikeda, Takashi; Chai, G.*; Hou, Z.*; Shu, D.*; Terakura, Kiyoyuki*
no journal, ,
no abstracts in English
Ikeda, Takashi; Chai, G.*; Hou, Z.*; Terakura, Kiyoyuki*
no journal, ,
Polymer electrolyte fuel cells are one of the most promising power sources. However, their practical use continues to be hindered by the prohibitive cost of Pt-based catalysts required to facilitate electrode reactions at operating temperatures of 80
C. Recently, a large number of groups have reported significantly high ORR activities of sp
carbon-based materials doped with light elements such as N, B, S, etc., thus leading to much debate on the role of the doped light elements in the ORR activity. In this computational study, we inspect possible oxygen adsorption and reduction processes on various models of N-doped defective graphene using FPMD simulations. The dynamics of an O molecule solvated in water along with energetic considerations, indicates that the N doping in defective graphenes can enhance efficiently their catalytic activity depending on the detailed structure of defects as well as the position of N dopants.
Ikeda, Takashi; Chai, G.*; Hou, Z.*; Terakura, Kiyoyuki*
no journal, ,
Recently, carbon-based nanomaterials doped with heteroatoms such as N are attracting a great interest as promising Pt-free electrode catalysts for polymer electrolyte fuel cells. For further enhancing their catalytic activity it is of crucial importance to identify catalytic sites of carbon-based materials and to elucidate reaction mechanisms at atomistic level. In this computational study, we inspect possible oxygen adsorption and reduction processes on various models of N-doped graphene using first principles-based molecular dynamics simulations. In this talk we summarize possible paths of oxygen reduction reaction and catalytic activity for N-doped carbon alloy catalysts suggested from our simulations.
