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Journal Articles

Estimation of the lifetime of resin insulators against baking temperature for JT-60SA in-vessel coils

Sukegawa, Atsuhiko; Murakami, Haruyuki; Matsunaga, Go; Sakurai, Shinji; Takechi, Manabu; Yoshida, Kiyoshi; Ikeda, Yoshitaka

Fusion Engineering and Design, 98-99, p.2076 - 2079, 2015/10

 Times Cited Count:1 Percentile:87.22(Nuclear Science & Technology)

The JT-60SA project is a EU - JA satellite tokamak under Broader Approach in support of the ITER project. In-vessel coils are designed and assembled by JA. The resin-insulator is required to have a heat resistance against the baking temperature of vacuum vessel of $$sim$$200$$^{circ}$$C (40000 hour). Thus the assessment of the heat load is fundamental for the design of the coils. However, the estimation of the lifetime of resin-insulator under the high-temperature region has not been examined. In the present study, the estimation of the lifetime of seven candidate resin-insulators such as epoxy resin and cyanate-ester resin under the $$sim$$220$$^{circ}$$C temperature region have been performed for the current coils design. Weight reduction of the seven candidate insulators was measured at different heating times under 180$$^{circ}$$C, 200$$^{circ}$$C and 220$$^{circ}$$C environment using three thermostatic ovens, respectively. The reduction of the insulators has been used as input for Weibull-analysis towards Arrhenius-plot. Lifetime of the resins has been estimated for the first time at the high temperature region by the plot. Lifetime of the resin-insulators have been evaluated and discussed as well as the available temperature of the in-vessel coils.

Journal Articles

Effect of magnetic field on positron lifetimes of Fe, Co and Ni

Li, H.; Maekawa, Masaki; Kawasuso, Atsuo; Tanimura, Naoki*

Journal of Physics; Condensed Matter, 27(24), p.246001_1 - 246001_5, 2015/06

 Times Cited Count:6 Percentile:64.62(Physics, Condensed Matter)

Journal Articles

Impact of carrier lifetime on efficiency of photolytic hydrogen generation by p-type SiC

Miyake, Keiko*; Yasuda, Tomonari*; Kato, Masashi*; Ichimura, Masaya*; Hatayama, Tomoaki*; Oshima, Takeshi

Materials Science Forum, 778-780, p.503 - 506, 2014/02

Journal Articles

Estimation of pitting damage induced by cavitation impacts

Soyama, Hitoshi*; Futakawa, Masatoshi; Homma, Kana*

Journal of Nuclear Materials, 343(1-3), p.116 - 122, 2005/08

 Times Cited Count:10 Percentile:40.24(Materials Science, Multidisciplinary)

In order to estimate life time of the mercury target vessel of spallation neutron source which will be subjected to cavitation impacts, prediction methods of pitting damage induced by the cavitation impact were proposed. It is very important to estimate incubation time, in which plastic deformation occurs without mass loss, because the thickness of vessel is very thin. In the present paper, two estimation methods were proposed. One of them is estimatiion from erosion test of severely damaged specimen by plotting the mass loss as a function of exposure time to cavitation on the logarithmic scales. Another method is the observation method of plastic deformation pits on damaged surface at very early period in incubation stage.

Journal Articles

Positron lifetime measurement on centrifuged Bi$$_{3}$$Pb$$_{7}$$ intermetallic compound

Ono, Masao; Huang, X. S.*; Shibata, Yasuhiro*; Iguchi, Yusuke*; Sakai, Seiji; Maekawa, Masaki; Chen, Z. Q.*; Osakabe, Toyotaka; Kawasuso, Atsuo; Naramoto, Hiroshi*; et al.

Proceedings of 1st International Conference on Diffusion in Solids and Liquids (DSL 2005), p.531 - 533, 2005/07

Recently, we formed atomic-scale graded structures in some miscible alloys and observed the decomposition in Bi$$_{3}$$Pb$$_{7}$$ intermetallic compound by sedimentation of atoms under strong gravitational field. In this study, we measured positron lifetime of centrifuged Bi$$_{3}$$Pb$$_{7}$$, to which the composition change was very small as it was treated at low temperature. It was found that the positron lifetime became longer than that of starting state. This indicated that the point defects (vacancy or divacancy) increased in the sample by centrifugal treatment. We are now investigating the relationship between increase in point defects and sedimentation of atoms.

JAEA Reports

Failure probability analysis on mercury target vessel

Ishikura, Shuichi*; Shiga, Akio*; Futakawa, Masatoshi; Kogawa, Hiroyuki; Sato, Hiroshi; Haga, Katsuhiro; Ikeda, Yujiro

JAERI-Tech 2005-026, 65 Pages, 2005/03

JAERI-Tech-2005-026.pdf:2.86MB

Failure probability analysis was carried out to estimate the lifetime of the mercury target which will be installed into the JSNS (Japan spallation neutron source) in J-PARC (Japan Proton Accelerator Research Complex). The lifetime was estimated as taking loading condition and materials degradation into account. Considered loads imposed on the target vessel were the static stresses due to thermal expansion and static pre-pressure on He-gas and mercury and the dynamic stresses due to the thermally shocked pressure waves generated repeatedly at 25 Hz. Materials used in target vessel will be degraded by the fatigue, neutron and proton irradiation, mercury immersion and pitting damages, etc. The imposed stresses were evaluated through static and dynamic structural analyses. The material-degradations were deduced based on published experimental data. As results, it was quantitatively confirmed that the failure probability for the lifetime expected in the design is very much lower, 10$$^{-11}$$ in the safety hull, meaning that it will be hardly failed during the design lifetime. On the other hand, the beam window of mercury vessel suffered with high-pressure waves exhibits the failure probability of 12%. It was concluded, therefore, that the leaked mercury from the failed area at the beam window is adequately kept in the space between the safety hull and the mercury vessel to detect mercury-leakage sensors.

Journal Articles

Luminescence study of lanthanide(III) ions in non-aqueous solutions containing azide ions

Lis, S.*; Kimura, Takaumi; Yoshida, Zenko; But, S.*

Journal of Alloys and Compounds, 380(1-2), p.173 - 176, 2004/10

 Times Cited Count:5 Percentile:60.8(Chemistry, Physical)

no abstracts in English

Journal Articles

Lifetime evaluation of graphite components for HTGRs

Oku, Tatsuo*; Ishihara, Masahiro

Nuclear Engineering and Design, 227(2), p.209 - 217, 2004/01

 Times Cited Count:27 Percentile:13.95(Nuclear Science & Technology)

The lifetime of graphite material and/or components has been discussed individually from different concepts, and sometimes gives confusion to material researchers as well as designers. The lifetime of graphite materials is determined based on the dimensional changes due to neutron irradiation, at which they return to their original dimensions after initially contracting. On the other hand, the lifetime of graphite components for HTGRs is defined based on a margin of the specified minimum ultimate strengths of the graphite to the stresses induced in the graphite components. As an example, the stresses induced in the graphite block for the HTTR were, then, compared with the limited stress value determined from the specified minimum ultimate strength, and the lifetime of the graphite component was evaluated and compared with that defined as dimensional changes. As a result, it was found that the lifetime of graphite components for HTGRs should be determined as the shorter one in the two lifetimes defined by the stress-strength relationship and by the dimensional changes.

Journal Articles

Relativistic many-body calculations of electric-dipole lifetimes, transition rates, and oscillator strengths for ${it n}$=3 states in Al-like ions

Safronova, U. I.*; Sataka, Masao; Albritton, J. R.*; Johnson, W. R.*; Safronova, M. S.*

Atomic Data and Nuclear Data Tables, 84(1), p.1 - 83, 2003/05

 Times Cited Count:36 Percentile:13.4(Physics, Atomic, Molecular & Chemical)

no abstracts in English

JAEA Reports

Structural integrity assessment of intermediate heat exchanger in the HTTR based on results of rise-to-power test

Takeda, Takeshi; Tachibana, Yukio; Nakagawa, Shigeaki

JAERI-Tech 2002-091, 45 Pages, 2002/12

JAERI-Tech-2002-091.pdf:1.77MB

no abstracts in English

Journal Articles

The Spectrum and laser properties of ytterbium doped phosphate glass at low temperature

Dai, S.*; Sugiyama, Akira; Hu, L.*; Liu, Z.*; Huang, G.*; Jiang, Z.*

Journal of Non-Crystalline Solids, 311(2), p.138 - 144, 2002/11

Low-temperature absorption and fluorescence spectra of the Yb3+ ions were measured in phosphate glass with compositions of (60-65)P$$_{2}$$O$$_{5}$$-(4-8)B$$_{2}$$O$$_{3}$$-(5-10)Al$$_{2}$$O$$_{3}$$-(10-15)K$$_{2}$$O-(5-10)BaO-(0-2)La$$_{2}$$O$$_{3}$$-(0-2)Nb$$_{2}$$O$$_{5}$$-(4-87)Yb$$_{2}$$O$$_{3}$$ in mol-%. Temperature dependence of lifetime from $$^{2}$$F$$_{5/2}$$ upper level of YB$$^{3+}$$ was investigated with a cryostat. The glass laser performance pumped by 940 nm laser diode was measured at different temperature range. At 8 K, glass laser oscillation had a slope efficiency of 4% and a maximum power of 2 mW at the peak laser wavelength of 1001 nm.

Journal Articles

Study of a new ytterbium doped phosphate laser glass

Dai, S.*; Hu, L.*; Sugiyama, Akira; Izawa, Yasukazu*; Liu, Z.*; Jiang, Z.*

Chinese Science Bulletin, 47(3), p.255 - 259, 2002/02

 Times Cited Count:7 Percentile:46.96(Multidisciplinary Sciences)

A new type of ytterbium doped phosphate laser glass has been produced and studied about physical and optical properties such as thermo-mechanical properties, nonlinear properties, crystalline phase, micro defects and spectroscopic properties. In the glass forming process, newly developed OH removing technology was adopted. From the reduction of OH concentration in the glass, upper state fluorescence lifetime reached 2.2 ms. Additionally, the glass shows remarkable athermal property of 0.42$$times$$10E$$^{-6}$$/K, which is around one-tenth of QX/Yb glass.

Journal Articles

High heat flux experiments of saddle type divertor module

Suzuki, Satoshi; Akiba, Masato; Araki, Masanori; Sato, Kazuyoshi; Yokoyama, Kenji; Dairaku, Masayuki

Journal of Nuclear Materials, 212-215(1), p.1365 - 1369, 1994/09

no abstracts in English

Journal Articles

A Positron lifetime study of defects in neutron-irradiated Si

A.Li*; H.Huang*; D.Li*; S.Zheng*; H.Du*; S.Zhu*; Iwata, Tadao

Japanese Journal of Applied Physics, 32(3), p.1033 - 1038, 1993/03

 Times Cited Count:8 Percentile:54.48(Physics, Applied)

no abstracts in English

Journal Articles

Positron annihilation study on neutron irradiated Si

S.Zhu*; A.Li*; S.Zheng*; H.Huang*; D.Li*; Iwata, Tadao

Chin. J. Nucl. Phys., 14(2), p.166 - 168, 1992/00

no abstracts in English

Journal Articles

New carbon stripper foils less shrinkable under heavy ion bombardment

;

Nuclear Instruments and Methods, 206, p.331 - 333, 1983/00

no abstracts in English

JAEA Reports

A Rotary Bandpass Filter for Lifetime Measurements of Reaction Products Induced by Heavy Ions

*; *; *; *; ; ; ;

JAERI-M 9901, 14 Pages, 1982/01

JAERI-M-9901.pdf:0.68MB

no abstracts in English

Journal Articles

Characterization of graphites by positron lifetimes

; *; *; *

Japanese Journal of Applied Physics, 20(10), p.1799 - 1806, 1981/00

 Times Cited Count:18 Percentile:33.92(Physics, Applied)

no abstracts in English

Journal Articles

Magnetic moment of the 2,140.2keV 5$$^{-}$$ state in $$^{1}$$$$^{3}$$$$^{6}$$Ba

; *; *; *; *; *

Hyperfine Interactions, 7(2), p.103 - 107, 1979/00

no abstracts in English

Journal Articles

Lifetime spectra of positrons in V$$_{2}$$O$$_{3}$$

; *; *; *

Journal of the Physical Society of Japan, 34(3), p.661 - 665, 1973/03

 Times Cited Count:8

no abstracts in English

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