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Journal Articles

In situ X-ray diffraction study of the oxide formed on alloy 600 in borated and lithiated high-temperature water

Watanabe, Masashi*; Yonezawa, Toshio*; Shobu, Takahisa; Shiro, Ayumi; Shoji, Tetsuo*

Corrosion, 72(9), p.1155 - 1169, 2016/09

 Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)

Journal Articles

In situ X-ray diffraction measurement method for investigating the oxides films on austenitic stainless steel in simulated pressurized water reactor primary water

Watanabe, Masashi*; Yonezawa, Toshio*; Shobu, Takahisa; Shoji, Tetsuo*

Corrosion, 71(10), p.1224 - 1236, 2015/10

 Times Cited Count:3 Percentile:19.61(Materials Science, Multidisciplinary)

Journal Articles

Carbon transport and fuel retention in JT-60U with higher temperature operation based on postmortem analysis

Yoshida, Masafumi; Tanabe, Tetsuo*; Adachi, Ayumu*; Hayashi, Takao; Nakano, Tomohide; Fukumoto, Masakatsu; Yagyu, Junichi; Miyo, Yasuhiko; Masaki, Kei; Itami, Kiyoshi

Journal of Nuclear Materials, 438, p.S1261 - S1265, 2013/07

 Times Cited Count:6 Percentile:46.6(Materials Science, Multidisciplinary)

Fuel retention rates and carbon re-deposition rates in the plasma shadowed areas in JT-60U were measured. Distributions of the fuel retention as well as the carbon re-deposition in the whole in-vessel of a large tokamak were clarified for the first time in the world. The fuel retention in the plasma shadowed areas was about two times larger than that in the carbon re-deposited layers on the plasma facing surface, although the amount of the carbon re-deposited on the plasma shadowed areas were about a half of that on the plasma facing surface, because of relatively lower temperature in the shadow areas causing higher hydrogen saturation concentration in the carbon re-deposited layers. The total fuel retention rate in JT-60U, including previously measured for all plasma facing areas, was evaluated to be 1.3$$times$$10$$^{20}$$ H+Ds$$^{-1}$$, which was lower than that in other devices, due to probably to higher temperature operation in JT-60U.

Journal Articles

Hydrogen isotopes retention in gaps at the JT-60U first wall tiles

Yoshida, Masafumi; Tanabe, Tetsuo*; Hayashi, Takao; Nakano, Tomohide; Fukumoto, Masakatsu; Yagyu, Junichi; Miyo, Yasuhiko; Masaki, Kei; Itami, Kiyoshi

Fusion Science and Technology, 63(1T), p.367 - 370, 2013/05

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

In this study, the retentions of hydrogen isotopes (H and D) in the gaps in JT-60U are clarified. Carbon tiles used in 1992-2004 were poloidally and toroidally taken out from outboard first wall in JT-60U to measure the retentions. The H and D retentions in the samples were measured by thermal desorption spectrometry (TDS). The H+D retention in the top side was higher than that of the bottom side, which might be due to thicker re-deposited carbon layers on the surface of the top side. The retentions in the surface of the side surfaces were slightly lower than that in the plasma facing surface where the retention was saturated to be 3-4e22 atoms/m$$^{2}$$. The retention rate was evaluated to be 3e17 H+D atoms/m$$^{2}$$/s from the measured retentions in two different discharge times by assuming the retention to increase linearly with the discharge time.

Journal Articles

In-vessel tritium

Ueda, Yoshio*; Oya, Kaoru*; Ashikawa, Naoko*; Ito, Atsushi*; Ono, Tadayoshi*; Kato, Daiji*; Kawashima, Hisato; Kawamura, Gakushi*; Kenmotsu, Takahiro*; Saito, Seiki*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 88(9), p.484 - 502, 2012/09

no abstracts in English

Journal Articles

Application of tritium tracer techniques to observation of hydrogen on surface and in bulk of F82H

Otsuka, Teppei*; Tanabe, Tetsuo*; Tokunaga, Kazutoshi*; Yoshida, Naoaki*; Ezato, Koichiro; Suzuki, Satoshi; Akiba, Masato

Journal of Nuclear Materials, 417(1-3), p.1135 - 1138, 2011/10

 Times Cited Count:2 Percentile:19.17(Materials Science, Multidisciplinary)

Journal Articles

Effects of carbon impurity on deuterium retention in VPS-tungsten coatings exposed to JT-60U divertor plasmas

Fukumoto, Masakatsu; Nakano, Tomohide; Itami, Kiyoshi; Wada, Takaaki*; Ueda, Yoshio*; Tanabe, Tetsuo*

Journal of Nuclear Materials, 415(Suppl.1), p.S705 - S708, 2011/08

 Times Cited Count:5 Percentile:40.36(Materials Science, Multidisciplinary)

Tungsten coating on the first wall in ITER is proposed to reduce in-vessel tritium retention. However, it is possibility that carbon based materials would be used at high heat load components such as limiter. To predict the tritium retention in tungsten coating, it is essential to investigate the effects of carbon impurity on deuterium retention in tungsten coating. In this study, effects of carbon impurity on deuterium retention in the tungsten coating exposed to JT-60U divertor plasmas were investigated. Deuterium was trapped by carbon which was implanted and accumulated in the tungsten coating during the plasma discharge. D/C ration of 0.04-0.08 in the tungsten coating was reached to 1/2-1/4 compared to T/C ration in carbon co-deposition layer. Therefore, simultaneous use of carbon armor materials and tungsten coating would enhance tritium retention in tungsten coating.

Journal Articles

Study on effectiveness assessment of proliferation resistance

Kuno, Yusuke; Oda, Takuji*; Tanaka, Satoru*; Fukasawa, Tetsuo*; Tanabe, Tomoyuki*; Tamai, Hiroshi; Horio, Kenta*; Hamasaki, Manabu*; Shinohara, Nobuo*; Ikeda, Yuta*

Proceedings of INMM 52nd Annual Meeting (CD-ROM), 10 Pages, 2011/07

The substance and implication of PR from the viewpoints of risk evaluation on nuclear proliferation was studied in this paper. As an example, ten next-generation reprocessing technology candidates were evaluated with GIF PR and PP methodology to find degree of relative difference in PR from the presently available technology - PUREX. PR effectiveness in proliferation risk was also assessed and it was found that the effectiveness of PR measures is subject to the status of each nation.

Journal Articles

Report on ITPA meeting, 33

Asakura, Nobuyuki; Ashikawa, Naoko*; Ueda, Yoshio*; Ono, Noriyasu*; Tanabe, Tetsuo*; Nakano, Tomohide; Masuzaki, Suguru*; Itami, Kiyoshi; Kawano, Yasunori; Kawahata, Kazuo*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 87(7), p.485 - 486, 2011/07

no abstracts in English

Journal Articles

Deuterium retention in tungsten coating on the CFC tiles exposed to JT-60U divertor plasmas

Fukumoto, Masakatsu; Nakano, Tomohide; Masaki, Kei; Itami, Kiyoshi; Ueda, Yoshio*; Tanabe, Tetsuo*

Journal of Plasma and Fusion Research SERIES, Vol.9, p.369 - 374, 2010/08

no abstracts in English

Journal Articles

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

Journal Articles

28th report on the ITPA (International Tokamak Physics Activity) meeting

Asakura, Nobuyuki; Nakano, Tomohide; Masuzaki, Takashi*; Ashikawa, Naoko*; Ueda, Yoshio*; Tanabe, Tetsuo*; Ono, Noriyasu*

Purazuma, Kaku Yugo Gakkai-Shi, 86(2), P. 124, 2010/02

no abstracts in English

Journal Articles

Experimental studies on in-vessel tritium inventory in complicated environment of fusion reactors

Ueda, Yoshio*; Hino, Tomoaki*; Ono, Noriyasu*; Takagi, Ikuji*; Nakano, Tomohide; Tanabe, Tetsuo*; Kajita, Shin*; Fukumoto, Masakatsu

Purazuma, Kaku Yugo Gakkai-Shi, 85(10), p.684 - 694, 2009/10

Relation between deuterium retention, wall temperature and hydrocarbon generation in 30-s H-mode discharges of JT-60U was described. In discharges with a density below 50% of the Greenwald density, the trend of the deuterium retention against pulse number depended on the wall temperature: with increasing pulse number, the deuterium retention decreased at a wall temperature of 300 $$^{circ}$$C, decreased gradually at 150 $$^{circ}$$C, and remained constant at 80 $$^{circ}$$C. In contrast, in discharges with high densities above 70% of the Greenwald density, the deuterium retention increased with increasing pulse number at the above three wall temperatures. In the high density discharges, the deuterium retention flux increased with increasing hydrocarbon generation flux, suggesting that the deuterium is retained in co-deposition layers of carbon, which originated from the hydrocarbons.

Journal Articles

Transport of heavy hydrocarbon and its redeposition on plasma facing walls

Oya, Kaoru*; Inai, Kensuke*; Kikuhara, Yasuyuki*; Nakano, Tomohide; Kawata, Jun*; Kawazome, Hayato*; Ueda, Yoshio*; Tanabe, Tetsuo*

Journal of Plasma and Fusion Research SERIES, Vol.8, p.419 - 424, 2009/09

Redeposition of C$$_{2}$$H$$_{4}$$ and C$$_{2}$$H$$_{6}$$ chemically eroded from carbon walls is simulated by EDDY code incorporated with the reflection on a hydrogenated and amorphized carbon surface. The redeposition rate for heavy hydrocarbons is drastically decreased by introduction of the reflection. The redeposition patterns on the surface are enlarged by the reflection, but it is narrower for the heavy hydrocarbons than for CH$$_{4}$$. The photon emissions of C$$_{2}$$ from C$$_{2}$$H$$_{4}$$ (C$$_{2}$$H$$_{6}$$) decay faster than that of CH from CH$$_{4}$$ in high-temperature ($$>$$10 eV) plasmas, which reproduces the difference of the decay of the CD and C$$_{2}$$ light intensities observed in the vicinity of the outer diverter plates of JT-60U. For such temperatures, the inverse photon-efficiency, which is defined as the ratio of the number of the launching hydrocarbons to the photoemission events of CH and C$$_{2}$$, is in good agreement with the values observed in JT-60U experiments.

Journal Articles

Hydrogen isotope retention in the outboard first wall tiles of JT-60U

Yoshida, Masafumi; Tanabe, Tetsuo*; Nobuta, Yuji*; Hayashi, Takao; Masaki, Kei; Sato, Masayasu

Journal of Nuclear Materials, 390-391, p.635 - 638, 2009/06

 Times Cited Count:9 Percentile:55(Materials Science, Multidisciplinary)

We have investigated hydrogen isotopes retention in the outboard first wall tiles of JT-60U by means of TDS, SIMS and SEM. The outboard first wall tiles of JT-60U are mostly eroded. The total retention (H+D) normalized by a unit area and integrated NBI time in the eroded first wall tiles and the eroded divertor tiles were nearly the same, in spite of the lower temperature of the first wall. Differently from divertor tiles, in which H retention was dominated owing to HH discharges preformed after DD discharges, deuterium is dominated in hydrogen isotopes retention and penetrates deeper from the surface. This is attributed to injection of high energy D and difficulty of isotopic replacement owing to their lower temperature. The integrated amount over the whole surface could be appreciably large. This type of hydrogen retention could be also possible for the metallic wall.

Journal Articles

Retention and depth profile of hydrogen isotopes in gaps of the first wall in JT-60U

Nobuta, Yuji*; Arai, Takashi; Yagyu, Junichi; Masaki, Kei; Sato, Masayasu; Tanabe, Tetsuo*; Yamauchi, Yuji*; Hino, Tomoaki*

Journal of Nuclear Materials, 390-391, p.643 - 646, 2009/06

 Times Cited Count:5 Percentile:37.11(Materials Science, Multidisciplinary)

The hydrogen and deuterium retention in gap side surfaces of the first wall tiles exposed to DD and HH discharges in JT-60U were investigated. The hydrogen and deuterium retention and boron deposition increased with the gap width. The depth profile of deuterium was very similar to that of boron, indicating that deuterium was incorporated with boron. Thick carbon deposition layer ($$sim$$ 1e$$^{-5}$$m) was observed in the gap of inboard tile and the atomic ratio in (H+D)/C at the carbon layer was estimated to be approximately 0.15. This value is higher than that observed in the divertor region. In this study, the H+D amount in gap side surfaces of the first wall was of the order of 1e23 $$sim$$ 1e24m$$^{-2}$$.

Journal Articles

Tritium removal by isotopic exchange

Tanabe, Tetsuo*; Sugiyama, Kazuyoshi*; Shibahara, Takahiro*; Hirohata, Yuko*; Yoshida, Masafumi; Masaki, Kei; Sato, Masayasu

Journal of Nuclear Materials, 390-391, p.705 - 708, 2009/06

 Times Cited Count:8 Percentile:50.97(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Deuterium depth profiling in graphite tiles not exposed to hydrogen discharges before air ventilation of JT-60U

Hayashi, Takao; Sugiyama, Kazuyoshi*; Mayer, M.*; Krieger, K.*; Masaki, Kei; Tanabe, Tetsuo*; Sato, Masayasu

Journal of Nuclear Materials, 390-391, p.667 - 670, 2009/05

 Times Cited Count:1 Percentile:10.52(Materials Science, Multidisciplinary)

Absolute concentrations and the depth profiles of D in plasma-facing graphite tiles used in JT-60U were determined by means of the D($$^{3}$$He, p)$$^{4}$$He resonant nuclear reaction. The analyzed samples were not exposed to H discharges before air ventilation. The maximum depth of analysis is about 1.4 $$times$$ 10$$^{24}$$ carbon (C) atoms/m$$^{2}$$, corresponding to a linear depth of 16 $$mu$$m for the density of 1.7 $$times$$ 10$$^{3}$$ kg/m$$^{3}$$. The highest D concentration was found at the inboard mid-plane of first wall area. The maximum D concentration is D/C=0.13, and the concentration decrease with the depth. The D retention within 16 $$mu$$m is 1.9 $$times$$ 10$$^{22}$$ D atoms/m$$^{2}$$. The D retentions in this paper were about 2$$sim$$9 times larger than previous samples, which were located on the same area and exposed to the hydrogen discharges. This indicates the H plasma discharges were effective to remove the D (and T) from graphite tiles in the first wall area.

Journal Articles

Development of highly sensitive sodium leak detection technology by means of laser for fast reactor (Fundamental experiments for atomization and resonance ionization of sodium and design of prototype sodium detection system)

Aoyama, Takafumi; Ito, Chikara; Okazaki, Koki*; Harano, Hideki*; Watanabe, Kenichi*; Iguchi, Tetsuo*

Nihon Kikai Gakkai Rombunshu, B, 75(751), p.468 - 470, 2009/03

no abstracts in English

Journal Articles

Multi-scattering time-of-flight neutron spectrometer for deuterium to tritium fuel ratio measurement in fusion experimental reactors

Asai, Keisuke*; Yukawa, Kyohei*; Iguchi, Tetsuo*; Naoi, Norihiro*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Yamauchi, Michinori*; Konno, Chikara

Fusion Engineering and Design, 83(10-12), p.1818 - 1821, 2008/12

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The fuel ratio in a DT burning plasma can be derived from the intensity ratio of DD/DT neutrons, and detecting a trace of DD neutrons in the DT burning plasma is a key issue. A new type of neutron spectrometer is proposed to monitor the fuel ratio in the core of the ITER plasma. The system based on a conventional time-of-flight method consists of a water cell as a neutron scattering material and tens of scintillator pairs arranged around the first scintillator in a corn shape. We call it a multi-scattering time-of-flight neutron spectrometer (MS-TOF). A trial experiment was conducted for the prototype MS-TOF system with a DT neutron beam (20-mm diameter) at the Fusion Neutronics Source (FNS), Japan Atomic Energy Agency. The experimental results show that the DD and DT neutron peaks are clearly observed, and the experiment has successfully demonstrated the feasibility of the MS-TOF concept for detecting trace-DD neutrons within a DT neutron beam extracted from a DT burn plasma.

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