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Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.
Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07
This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.
Cs washoff from bare land in FukushimaIgarashi, Yasunori*; Onda, Yuichi*; Wakiyama, Yoshifumi*; Yoshimura, Kazuya; Kato, Hiroaki*; Kozuka, Shohei*; Manome, Ryo*
Science of the Total Environment, 769, p.144706_1 - 144706_9, 2021/05
Times Cited Count：2 Percentile：13.39(Environmental Sciences)Kato, Masaru*; Nakahoshiba, Ryota*; Ogura, Kazuya*; Tokuda, Shoichi*; Yasuda, Satoshi; Higashi, Kotaro*; Uruga, Tomoya*; Uemura, Yohei*; Yagi, Ichizo*
ACS Applied Energy Materials (Internet), 3(7), p.6768 - 6774, 2020/07
Times Cited Count：15 Percentile：62.59(Chemistry, Physical)To understand electronic effects of nitrogen-doped and polymer-coated carbon supports on the catalytic activity of Pt-based nanostructured catalysts, we prepared Pt
Ni nanoframes (NFs) supported on polybenzimidazole (PBI)-coated and uncoated carbon nanotubes for the oxygen reduction reaction (ORR), and then compared their catalytic activities and electronic properties with those of NFs immobilized on nitrogen-doped and undoped carbon supports. Although both PBI-coating and nitrogen-doping approaches improved the catalytic activity of NFs, 
X-ray photoelectron spectroscopy and 
X-ray absorption spectroscopy revealed that nitrogen doping showed electronic effects on NFs, whereas PBI-coating showed almost no impact on the electronic state of NFs but stabilized Pt(OH)
species under electrochemical conditions. Our studies demonstrate that difference in microscopic environments of nitrogen atoms at the catalyst/support interface is highly sensitive to the electronic effects of supports on Pt-based electrocatalysts.
Kawasaki, Masatsugu; Nakajima, Junya; Yoshida, Keisuke; Kato, Saori; Nishino, Sho; Nozaki, Teo; Nakagawa, Masahiro; Tsunoda, Junichi; Sugaya, Yuki; Hasegawa, Rie; et al.
JAEA-Data/Code 2017-004, 57 Pages, 2017/03
JAEA-Data-Code-2017-004.pdf:2.34MB
In emergency situation of nuclear facilities, we need to estimate the radiation dose due to radiation and radioactivity to grasp the influence range of the accident in the early stage. Therefore, we prepare the case studies of dose assessment for public exposure dose and personal exposure dose and contribute them to emergency procedures. This document covers about accidents of nuclear facilities in Nuclear Science Research Institute and past accident of nuclear power plant, and it can be used for inheritance of techniques of emergency dose assessment.
(Al,Ga)
O
scintillator Compton camera mounted on an unmanned helicopterShikaze, Yoshiaki; Nishizawa, Yukiyasu; Sanada, Yukihisa; Torii, Tatsuo; Jiang, J.*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Yoshino, Masao*; Ito, Shigeki*; Endo, Takanori*; et al.
Journal of Nuclear Science and Technology, 53(12), p.1907 - 1918, 2016/12
Times Cited Count：37 Percentile：96.48(Nuclear Science & Technology)The Compton camera was improved for use with the unmanned helicopter. Increase of the scintillator array from 4
4 to 88 and expanse of the distance between the two layers contributed to the improvements of detection efficiency and angular resolution, respectively. Measurements were performed over the riverbed of the Ukedo river of Namie town in Fukushima Prefecture. By programming of flight path and speed, the areas of 65 m 60 m and 65 m 180 m were measured during about 20 and 30 minutes, respectively. By the analysis the air dose rate maps at 1 m height were obtained precisely with the angular resolution corresponding to the position resolution of about 10 m from 10 m height. Hovering flights were executed over the hot spot areas for 10-20 minutes at 5-20 m height. By using the reconstruction software the 
-ray images including the hot spots were obtained with the angular resolution same as that evaluated in the laboratory (about 10
).
Kimata, Tetsuya*; Kato, Sho*; Yamaki, Tetsuya; Yamamoto, Shunya; Kobayashi, Tomohiro*; Terai, Takayuki*
Surface & Coatings Technology, 306(Part A), p.123 - 126, 2016/11
Times Cited Count：13 Percentile：52.49(Materials Science, Coatings & Films)Platinum (Pt) nanoparticle catalysts with oxygen reduction reaction (ORR) activity are required for practical applications of polymer electrolyte fuel cells. We prepared Pt nanoparticles on an Ar
-irradiated glassy carbon (GC) surface by a radio-frequency magnetron sputtering method to investigate the influence of the ion-induced lattice defects in GC on the ORR activity of the deposited Pt nanoparticles. Interestingly, the Pt nanoparticles on the irradiated surface exhibited ca. 2.5 times higher specific activity than those on the non-irradiated one. X-ray photoelectron spectroscopy suggested the interfacial Pt-C interaction occurring between the irradiated GC and Pt nanoparticles, which should be a reason for improvement of the ORR activity.
V
Al alloysSoda, Kazuo*; Harada, Shota*; Hayashi, Toshimitsu*; Kato, Masahiko*; Ishikawa, Fumihiro*; Yamada, Yu*; Fujimori, Shinichi; Saito, Yuji
Materials Transactions, 57(7), p.1040 - 1044, 2016/06
Times Cited Count：2 Percentile：12.27(Materials Science, Multidisciplinary)Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
Nuclear Instruments and Methods in Physics Research B, 314, p.149 - 152, 2013/11
Times Cited Count：2 Percentile：19.73(Instruments & Instrumentation)We implanted 100 keV W in unpolished GC substrates at nominal fluences up to 
ions/cm
. The implanted samples were electrochemically anodized in a NaOH aqueous solution to etch the surface layer. The analyses were performed by X-ray photoelectron spectroscopy (XPS), Rutherford backscattering spectrometry (RBS), and transmission electron microscopy (TEM). XPS W 4f spectra indicated the formation of carbides as reported previously. The electrochemical etching clearly increased the W concentration on the surface. According to the RBS results, half of the implanted W atoms were retained in the substrate, while the rest should escape to the etching solution. The cross-sectional TEM image revealed a uniform distribution of WC particles with a diameter of less than 10 nm just near the surface region.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
Transactions of the Materials Research Society of Japan, 38(1), p.81 - 84, 2013/03
Nanoparticles were formed by 100 keV tungsten-ion implantation in unpolished glassy carbon substrates at nominal fluences of 
- 
ions/cm. The implanted samples were analyzed by Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy, hydrodynamic voltammetry using a rotating disk electrode, and field emission scanning electron microscopy. A significant sputtering effect changed the depth profile during the course of irradiation and limited the amount of tungsten retainable in the substrate in agreement with our calculated distributions. The nanoparticles were composed of tungsten carbide and dispersed uniformly with diameters of around 10 nm.
Sekimoto, Hitoshi*; Kawachi, Naoki; Honda, Shuzo*; Yamaguchi, Yoshie*; Kato, Shota*; Yoneyama, Kaori*; Fujimaki, Shu; Suzui, Nobuo; Ishii, Satomi; Watanabe, Satoshi; et al.
JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 124, 2008/03
no abstracts in English
Sekimoto, Hitoshi; Honda, Shuzo*; Kato, Shota*; Ochiai, Yukiko*; Yoneyama, Kaori*; Yoneyama, Koichi*; Takeuchi, Yasutomo*; Kawachi, Naoki; Fujimaki, Shu; Suzui, Nobuo; et al.
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 125, 2007/02
Jo, Akinori*; Kato, Shota*; Matsuura, Hirotaka*; Nagata, Kazumi*; Katakai, Akio; Tamada, Masao
no journal, ,
no abstracts in English
Yamaki, Tetsuya; Kato, Sho*; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
We prepared nanoparticles of tungsten (W) carbides by W-ion implantation in an unpolished glassy carbon (GC) substrate and then examined, for the first time, their composition, electrochemical properties, and morphology. The W
implantation was performed at room temperature using an energy of 100 keV and nominal fluences of up to 1.810
ions/cm
. Due to a significant sputtering effect and chemical interation between the implants and substrate, mostly W carbides, a mixture of WC and W
C phases, were formed on the surface. The subsequent electrochemical etching in an alkaline solution achieved the smooth surface with maximum area density of the carbide phases. Particulate aggregates were found to contain spherical nanoparticles with a diameter of 
10 nm.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
In this research, we prepared WC nanoparticles by tungsten ion implantation in glassy carbon. The GC plates were implanted with 100-keV tungsten ion at nominal fluences between 2.410
1.810 ions/cm by the Ion Implanter in TIARA. According to the Rutherford backscattering measurements, the implanted tungsten was distributed from 10 to 25 nm under the surface. The implanted samples were electrochemically etched to make the tungsten implanted layer exposed on the surface. The binding energy of W4f
obtained by X-ray photoelectron spectroscopy were 32.1 eV, which indicated the formation of WC as expected. The transmission electron microscope observation revealed that nanoparticles formation with diameters of less than 10 nm.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Glassy carbon substrates were implanted with 100-keV platinum ions at fluences between 710
and 410 ions/cm. The unimplanted samples were surface-etched electrochemically and thermally treated in order to prepare platinum nanoparticles on their topmost layer. Scanning electron microscope observation revealed the platinum nanoparticles with a diameter of a few tens of nanometers on the surface. The voltammogram using a rotating disk electrode showed large cathodic current due to oxygen reduction reaction activity of the obtained nanoparticles.
Yamaki, Tetsuya; Kato, Sho; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Chemical transformations involved during ion implantation can lead to material modifications. Our focus here was on the interaction of tungsten (W) ions implanted in glassy carbon (GC). Recent studies dealt with nanosized particles of W carbides in a W-ion-implanted GC substrate in terms of their composition, electrochemical properties, and morphology. In this paper, we discuss a detailed study of compound formation resulting from W implants in GC for the first time, emphasizing the importance of chemical interactions in determining the final properties of the implanted layer.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Ion implantation is a kind of technique to prepare nanoparticles. To prepare platinum (Pt) nanoparticle catalysts, it is very important to control their size. In this research, the process of particle growth was elucidated by in-situ transmission electron microscopy. In the experiment, glassy carbon substrates were implanted with 100 keV Pt ions at the fluences of 710410ions/cm. The electrochemical etching was applied to expose the implanted layer. Finally, thermal treatment was conducted to form nanoparticles. Before the thermal treatment, the each implanted Pt were seemed to be monoatomic. When the temperature of the sample reached 375C, the Pt atoms started to aggregate, and formed uniformly dispersed nanoparticles with diameters of 5 nm. This result indicated that the controllability of our nanoparticle preparation method is high enough to prepare the Pt nanoparticle for cathode catalysts in fuel cells.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Pt nanoparticle catalysts prepared by ion implantation are expected to show high durability in fuel cell applications. In this research, the electrochemical stability of the Pt nanoparticles as oxygen reduction catalyst was evaluated.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Platinum nanoparticle catalysts for fuel cell applications were prepared by ion implantation in a glassy carbon substrate followed by electrochemical etching and thermal treatment. Interestingly, they had a strong interaction with the substrate via platinum-carbon bonds, probably thereby achieving high catalytic activity for the oxygen reduction reaction.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Platinum nanoparticle catalysts for fuel cell applications were prepared by ion implantation in a glassy carbon substrate followed by electrochemical etching and thermal treatment. Interestingly, they had a strong interaction with the substrate via platinum-carbon bonds, probably thereby achieving high catalytic activity for the oxygen reduction reaction.
