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PtS
Li, D.*; Yamamura, Tomoo*; Homma, Yoshiya*; Yubuta, Kunio*; Shikama, Tatsuo*; Aoki, Dai*; Nimori, Shigeki*; Haga, Yoshinori
Journal of the Korean Physical Society, 62(12), p.2233 - 2238, 2013/06
Times Cited Count：3 Percentile：27.27(Physics, Multidisciplinary)To, Kentaro; Shikama, Tatsuo*
Reza Kenkyu, 41(5), p.332 - 336, 2013/05
There are fewer devices which have a long-term stability used in a heavy irradiation environment such as nuclear power plant and accelerator. And, the nuclear accident at Fukushima-1 revealed importance of visualization of core parts of nuclear systems, where heavy radiation field will hider easy access. Fused silica based optical fibers will be one among the strongest candidates for visualization of the fields. The paper will describe the present status of development and its application of radiation resistant optical fibers.
Nishitani, Takeo; Yamanishi, Toshihiko; Tanigawa, Hiroyasu; Nozawa, Takashi; Nakamichi, Masaru; Hoshino, Tsuyoshi; Koyama, Akira*; Kimura, Akihiko*; Hinoki, Tatsuya*; Shikama, Tatsuo*
Fusion Engineering and Design, 86(12), p.2924 - 2927, 2011/12
Times Cited Count：7 Percentile：48.91(Nuclear Science & Technology)Several technical R&D activities related to the blanket materials are newly launched as a part of the Broader Approach (BA) activities, which was initiated by the EU and Japan. According to the common interests of these parties for DEMO, R&Ds on reduced activation ferritic/martensitic (RAFM) steels as structural material, SiCf/SiC composites as a flow channel insert material and/or alternative structural material, advanced tritium breeders and neutron multipliers, and tritium technology are carried out through the BA DEMO R&D program, in order to establish the technical bases on the blanket materials and the tritium technology required for DEMO design. This paper describes overall schedule of those R&D activities and recent progress in Japan carried out by JAEA as the domestic implementing agency on BA, collaborating with Japanese universities and other research institutes.
Nishitani, Takeo; Tanigawa, Hiroyasu; Nozawa, Takashi; Jitsukawa, Shiro; Nakamichi, Masaru; Hoshino, Tsuyoshi; Yamanishi, Toshihiko; Baluc, N.*; M
slang, A.*; Lindou, R.*; et al.
Journal of Nuclear Materials, 417(1-3), p.1331 - 1335, 2011/10
Times Cited Count：14 Percentile：71.96(Materials Science, Multidisciplinary)As a part of the Broader Approach (BA) activities, the research and development on blanket related materials and tritium technology have been initiated toward DEMO by Japan and EU. Recently, those five R&D items have progressed substantially in Japan and EU. As a preparatory work aiming at the RAFM steel muss-production development, a 5-ton heat of RAFM steel (F82H) was procured with the Electro Slag Re-melting as a secondary melting. The result of the double notch tensile test method for the NITE-SiC
/SiC specimen indicated notch insensitivity and very minor size effect on proportional limit tensile stress and fracture strength. For the fabrication technology development of beryllide neutron multiplayer pebbles, Be- Ti inter-metallic pebbles have been sintered directly from the mixed powder of Be and Ti in Japan.
To, Kentaro; Sakasai, Kaoru; Nakamura, Tatsuya; Soyama, Kazuhiko; Shikama, Tatsuo*
Journal of Nuclear Materials, 417(1-3), p.814 - 817, 2011/10
Times Cited Count：10 Percentile：57.01(Materials Science, Multidisciplinary)Plastic optical fibers (POFs) are very useful and widely used for signal transmission because they have the following advantages: (1) they do not produce electrical noise, (2) they are inexpensive and lightweight, and (3) they have wide optical signal bands. In this study, the effects of 14-MeV neutron and 
-ray irradiation on a POF were investigated. Strong radiation damage (radiation-induced transmission loss) was caused by irradiation with both neutrons and -rays, particularly at short wavelengths. To determine the effects of neutron and -ray irradiation, the amount of energy absorbed in the PMMA POF was calculated by using a Monte Carlo simulation using PHITS code. The similar radiation effect with both neutrons and -rays was observed at an absorbed energy less than 5
10
eV.
AgInLi, D. X.*; Yamamura, Tomoo*; Yubuta, Kunio*; Nimori, Shigeki*; Haga, Yoshinori; Shikama, Tatsuo*
Journal of Physics; Conference Series, 320, p.012041_1 - 012041_6, 2011/09
Times Cited Count：9 Percentile：89.02(Physics, Condensed Matter)PdSiLi, D. X.*; Kimura, Akihiro*; Haga, Yoshinori; Nimori, Shigeki*; Shikama, Tatsuo*
Journal of Physics; Condensed Matter, 23(7), p.076003_1 - 076003_7, 2011/02
Times Cited Count：12 Percentile：47.09(Physics, Condensed Matter)Nagata, Shinji*; Fujita, Haruka*; Inoue, Aichi; Yamamoto, Shunya; Tsuchiya, Bun*; Shikama, Tatsuo*
Nuclear Instruments and Methods in Physics Research B, 268(19), p.3151 - 3154, 2010/10
Times Cited Count：3 Percentile：28.83(Instruments & Instrumentation)A tungsten tri-oxide (WO
) film covered with a thin catalyst layer is one of the candidates for hydrogen sensing devices that show a reversible coloration under hydrogen exposure. While the injection of the cations and/or the formation of the oxygen vacancies can be responsible for the coloration of the film, the mechanism of the gasochromic phenomenon is not fully understood. In the present work, the changes of the optical properties in the WO film by ion irradiation were investigated to clarify the relation between the coloration and oxygen vacancies. WO films of 300-500 nm thicknesses were deposited on SiO
substrates by magnetron sputtering. Oxygen ions at energies between 200 and 800 keV were irradiated to the WO films. The optical absorption of the film was measured in the wavelengths between 190 and 1000 nm. The results show that the change of optical-absorption coefficient in WO films depends on both electronic and nuclear stopping powers.
Nishitani, Takeo; Tanigawa, Hiroyasu; Jitsukawa, Shiro; Nozawa, Takashi; Hayashi, Kimio; Yamanishi, Toshihiko; Tsuchiya, Kunihiko; Mslang, A.*; Baluc, N.*; Pizzuto, A.*; et al.
Journal of Nuclear Materials, 386-388, p.405 - 410, 2009/04
Times Cited Count：31 Percentile：87.96(Materials Science, Multidisciplinary)The establishment of the breeding blanket technology is one of the most important engineering issues on the DEMO development. For the DEMO blanket, developments of the structural materials and functional materials such as tritium breeder and neutron multiplier. Which should be used under the savior circumstance such as high neutron fluence, high temperature and strong magnetic field, are urgent issues. In the Broader Approach activities initiated by EU and Japan, developments of reduced activation ferritic martensitic steels as a DEMO blanket structural material, SiC/SiC composites, advanced tritium breeders and neutron multiplier for DEMO blankets, are planed as common interest issues of EU and Japan. This paper describes the overview of the development program.
To, Kentaro; Shikama, Tatsuo*; Katsui, Hirokazu*; Nagata, Shinji*; Tsuchiya, Bun*; Yamauchi, Michinori*; Nishitani, Takeo
Journal of Nuclear Materials, 386-388, p.1027 - 1029, 2009/04
Times Cited Count：4 Percentile：30.49(Materials Science, Multidisciplinary)Fluorescence and long-lasting emission properties of two types of Long-lasting phosphors (LLPs), SrAlO
:Eu
,Dy
and SrAl
O
:Eu,Dy, were examined under 14-MeV neutron irradiation. The fluorescent spectra of the LLPs have characteristic peaks due to their dopants and the fluorescent intensity of SrAlO:Eu,Dy shows good radiation resistance for the neutrons fluence up to 10
n/m
. Long-lasting emissions are exhibited after neutron irradiation, and the emission spectra have one peak due to Eu. Further, it is found that there is an optimum neutron fluence at which the longest decay time is obtained.
Nagata, Shinji*; Katsui, Hirokazu*; Tsuchiya, Bun*; Inoue, Aichi; Yamamoto, Shunya; To, Kentaro; Shikama, Tatsuo*
Journal of Nuclear Materials, 386-388, p.1045 - 1048, 2009/04
Times Cited Count：14 Percentile：66.94(Materials Science, Multidisciplinary)no abstracts in English
Inoue, Aichi; Yamamoto, Shunya; Nagata, Shinji*; Yoshikawa, Masahito; Shikama, Tatsuo*
Nuclear Instruments and Methods in Physics Research B, 267(8-9), p.1480 - 1483, 2009/03
Times Cited Count：12 Percentile：62.36(Instruments & Instrumentation)We quantitatively studied the relation between hydrogen retention and optical properties induced by hydrogen ion implantation in tungsten trioxide (WO) films. Films of WO (300 nm) covered with tungsten metal layers (200 nm) were prepared on transparent SiO substrates by a reactive sputtering in Ar and O mixture. When H
ions were implanted into the samples at an acceleration voltage of 10 kV, the concentration of hydrogen retaining in the WO films increased up to 0.4 H/W in proportion to the fluence of H ions. The optical absorption coefficient at 750 nm of samples increased linearly by 3 
m
with increasing the concentration of hydrogen implanted up to 0.1 H/W. And then, increased and saturated at 4 m with the increase of hydrogen concentration higher than 0.1 H/W. It was found that the hydrogen retention up to 0.1 H/W in tungsten trioxide layers can be monitored by measuring the optical absorbance.
Nagata, Shinji*; Sasase, Masato*; Takahiro, Katsumi*; Tsuchiya, Bun*; Inoue, Aichi; Yamamoto, Shunya; Shikama, Tatsuo*
Nuclear Instruments and Methods in Physics Research B, 267(8-9), p.1514 - 1517, 2009/03
Times Cited Count：9 Percentile：53.48(Instruments & Instrumentation)In this study, effects of the ion implantation on the phase transformation and nano-crystalline formation were examined in Zr-based metallic glasses. Samples were 2 mm thick plates and thin films of Zr
Al
Ni
Cu
prepared by casting in a copper mold and by using RF magnetron sputtering, respectively. Ions of Mg, P, Au and Bi with 100-500 keV were implanted in the samples up to 2 10 ions/cm at room temperature. Nano-crystalline structure was found in implanted samples by TEM observation, while the long-range order in the structure was not found for the X-ray diffraction patterns. The electron diffraction patterns indicated the formation of fcc-ZrCu in the P, Au, and Bi implanted region. Changes of the binding energy of the core level electron and valence band structure suggested the formation of Au-Zr or Au-Cu alloys in the Au ion implanted region.
Shikama, Tatsuo*; Knitter, R.*; Konys, J.*; Muroga, Takeo*; Tsuchiya, Kunihiko; Mslang, A.*; Kawamura, Hiroshi; Nagata, Shinji*
Fusion Engineering and Design, 83(7-9), p.976 - 982, 2008/12
Times Cited Count：37 Percentile：90.06(Nuclear Science & Technology)Functional materials should play an important role not only in ITER but also in fusion machines beyond ITER, though it is occasionally claimed that future fusion plants should have much more simple structures and they should be free from auxiliary systems such as diagnostics. Studies on test blanket modules (TBM) clearly show the importance of functional materials there. The paper will review the present status of studies and developments of functional ceramics for nuclear fusion applications, with a perspective on their application in electric-power generating fusion power plant, namely DEMO.
Inoue, Aichi; Yamamoto, Shunya; Nagata, Shinji*; Yoshikawa, Masahito; Shikama, Tatsuo*
Transactions of the Materials Research Society of Japan, 33(4), p.1127 - 1130, 2008/12
We investigated effects of catalyst on gasochromic properties in tungsten oxide films. Amorphous WO films coated with Pd and Pt catalysts were prepared on SiO substrates by employing reactive RF magnetron sputtering. The field emission scanning electron microscope (FE-SEM) showed that particles with a dozes nm diameter of Pd and with a few nm of Pt grew on the surface at beginning of deposition. The continuous catalytic layers were observed with increasing the amounts of more than 2 nm for Pd and 0.2 nm for Pt catalysts, respectively. When the continuous layers formed on WO surface, the excellent gasochromic properties were obtained. The results indicated that Pt catalysts were suitable for high sensitive hydrogen sensors consisting of gasochromic WO films.
Nishitani, Takeo; Ishitsuka, Etsuo; To, Kentaro; Shikama, Tatsuo*; Takahashi, Koji
Purazuma, Kaku Yugo Gakkai-Shi, 84(10), p.635 - 645, 2008/10
no abstracts in English
Inoue, Aichi; Yamamoto, Shunya; Nagata, Shinji*; Yoshikawa, Masahito; Shikama, Tatsuo*
Nuclear Instruments and Methods in Physics Research B, 266(15), p.3381 - 3386, 2008/08
Times Cited Count：5 Percentile：38.65(Instruments & Instrumentation)The effects of composition and structure on hydrogen incorporation property in tungsten oxide films were investigated. The tungsten oxide was deposited on carbon and SiO substrates to form films by varying the temperature from 30 to 600 
C using a reactive sputtering in argon and oxygen mixture. We obtained amorphous structure in the films deposited below 400 C and (0 1 0) oriented monoclinic WO in the films deposited beyond 400 C. Hydrogen concentration in the films increased from 0.1 to 0.7 H/W with changing the composition from WO
to WO. The hydrogen concentration in WO films decreased to 0.4 H/W with increasing the substrate temperature during deposition. The Raman spectra of the WO films revealed that decreasing of W
=O terminals was related to that of the hydrogen concentration. It was considered in detail that the incorporated hydrogen in tungsten oxide films was bonded at the end of W=O terminals.
-phase zirconium hydrides and deuteridesTsuchiya, Bun*; Yasuda, Ryo; Teshigawara, Makoto; Konashi, Kenji*; Nagata, Shinji*; Shikama, Tatsuo*; Yamawaki, Michio*
Journal of Nuclear Materials, 376(1), p.60 - 65, 2008/05
Times Cited Count：2 Percentile：16.99(Materials Science, Multidisciplinary)Distributions of hydrogen isotope concentrations in e-phase zirconium hydrides and deuterides (-ZrHx and -ZrDx: 1.8 
x 2.0) were investigated by neutron radiography (NRG). The NRG images of the thermal neutron transmission and backscattering revealed hydrogen concentration dependence and isotope differences. The thermal neutron mass attenuation coefficients in relation to the hydrogen isotope concentrations were determined from the transmission NRG images. The results showed the isotope effects of the thermal neutron mass attenuation coefficients for -ZrHx to be about 6-9 times higher than those for -ZrDx. The neutron scattering processes for transmission and backscattering NRG images of -ZrHx and -ZrDx were also analyzed using a general Monte Carlo neutron-particle transport (MCNP) code.
Inoue, Aichi; Yamamoto, Shunya; Nagata, Shinji*; Yoshikawa, Masahito; Shikama, Tatsuo*
Nuclear Instruments and Methods in Physics Research B, 266(2), p.301 - 307, 2008/01
Times Cited Count：14 Percentile：66.71(Instruments & Instrumentation)Changes in the composition and crystalline structure of gasochromic tungsten oxide films resulting from the incorporation of hydrogen were investigated. An uniaxial oriented films in the (0 1 0) plane of monoclinic WO were obtained by reactive RF magnetron sputtering at 600 C. The elastic recoil detection analysis for the films on glassy carbon revealed that the hydrogen impurity was uniformly distributed up to a concentration of 0.24 H/W. The Pd-coated films on SiO turned to blue when they were exposed to a mixture of Ar and 5% H gases. When the sample became colored, the hydrogen concentration in the film increased to 0.47 H/W and the crystalline structure of the film changed from monoclinic to tetragonal. These results indicated that the gasochromic coloration of the tungsten oxide films was accompanied by formation of hydrogen compounds called tungsten bronze (H
WO).
Nagata, Shinji*; Inoue, Aichi; Yamamoto, Shunya; Tsuchiya, Bun*; Takano, Katsuyoshi; To, Kentaro*; Shikama, Tatsuo*
Journal of Alloys and Compounds, 446-447, p.558 - 561, 2007/10
Times Cited Count：20 Percentile：69.88(Chemistry, Physical)The effect of the composition of non-stoichiometric WO films on the gasochromic coloration are investigated. The films are prepared by a reactive RF magnetron sputtering with varying oxygen partial pressure. To determine the quantitative composition of deposited films, Rutherford backscattering spectroscopy (RBS) and Elastic recoil detection (ERD) are employed. Gasochromic coloration of the films coated with Pd catalyst is examined by optical transmission in hydrogen gas. O/W atomic ratio of the films increases from 0.25 to 3.0 with increasing the oxygen partial pressure in the sputtering gas. H/W ratio increases up to 0.7 with increasing the O/W ration. As regards gasochromic coloration, the film with O/W atomic ratio of 3.0 shows superior coloration performance comparing with that of less than 3.0. Therefore, it is assumed that the good gasochromic coloration of tungsten oxide films is realized by near-stoichiometric WO. In addition, gasochromic coloration state, increasing of hydrogen concentration in WO films is observed. It indicates that gasochromic coloration of WO is relate to formation of HWO structure.
