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Higemoto, Wataru; Yokoyama, Makoto*; Ito, Takashi; Suzuki, Taiga*; Raymond, S.*; Yanase, Yoichi*
Proceedings of the National Academy of Sciences of the United States of America, 119(49), p.e2209549119_1 - e2209549119_6, 2022/11
Times Cited Count：0 Percentile：0(Multidisciplinary Sciences)no abstracts in English
Matsushita, Kentaro; Ezure, Toshiki; Imai, Yasutomo*; Fujisaki, Tatsuya*; Tanaka, Masaaki
Nihon Kikai Gakkai Kanto Shibu Ibaraki Koenkai 2021-Nendo Koen Rombunshu (Internet), 4 Pages, 2021/08
For evaluation of gas entrainment phenomenon at free surface in reactor vessel of sodium-cooled fast reactor, the gas entrainment evaluation tool named "Stream Viewer" has been developed. In Stream Viewer, depth of surface vortex dimple is predicted by calculating pressure decrease at the vortex center using velocity distribution around the vortex and Burgers vortex model. In this report, a method to identify continuous vortex center lines from a velocity distribution is newly developed. It becomes possible to evaluate three-dimensional distribution of pressure decrease along vortex center line. Then, the method is validated by applying Stream Viewer to an open channel experiment. As the result, it was confirmed that vortex center lines were successfully identified by the improved Stream Viewer. Moreover, it was also shown that the evaluation accuracy of gas entrainment was expected to be improved by considering distribution of pressure decrease along vortex center line.
Yokoyama, Keiichi; Matsuoka, Leo*
Ryoshi Woku No Shin Tenkai; Suri Kozo No Shinka To Oyo, p.228 - 242, 2019/08
Quantum walk is the quantum mechanical counter part of the classical random walk, which is known as mathematical model of diffusion process. By applying this new concept to light-matter interaction, a new isotope separation scheme is shown to be emerged. In addition, its advancements and forthcoming challenges are introduced.
Fujita, Shunya*; Abe, Yutaka*; Kaneko, Akiko*; Yuasa, Tomohisa*; Segawa, Tomoomi; Kato, Yoshiyuki; Kawaguchi, Koichi; Ishii, Katsunori
Proceedings of 11th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-11) (Internet), 7 Pages, 2018/11
Mixed uranium oxide and plutonium oxide powder is produced from uranyl nitrate and plutonium nitrate mixed solution by the microwave heating denitration method in the spent fuel reprocessing process. Since the microwave heating method is accompanied by a boiling phenomenon, it is necessary to fully grasp the operating conditions in order to avoid flashing and spilling in the mass production of denitrification technology for the future. In this research, it was clarified that the heat transfer coefficient became lower as the dielectric constant increased. The dominant factor of the blowing up phenomena is supposed to be generation of the innumerable bubble rather than bubble's growth.
Tanaka, Masaaki
Proceedings of 12th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-12) (USB Flash Drive), 14 Pages, 2018/10
A numerical simulation code MUGTHES has been developed to estimate high cycle thermal fatigue in SFRs. In development of numerical simulation code, verification, validation, and uncertainty quantification (VVUQ) are indispensable. In this study, numerical simulation at impinging jet condition in the WATLON experiment which was the water experiment of a T-junction piping system was performed for the fundamental validation. Based on the previous studies, the simplified least square version GCI method and the area validation metrics were employed as reference methods to quantify uncertainty and to measure the degree of difference between the numerical and the experimental results, respectively. Through the examinations, the potential applicability of the MUGTHES to the thermal striping phenomena was indicated and requirements of modification in the simulation was suggested in accordance with the uncertainty values.
Kurata, Masaki; Barrachin, M.*; Haste, T.*; Steinbrueck, M.*
Journal of Nuclear Materials, 500, p.119 - 140, 2018/03
Times Cited Count：29 Percentile：66.35(Materials Science, Multidisciplinary)Severe accidents occurred at the Fukushima-Daiichi Nuclear Power Station (FDNPS) required an immediate re-examination of fuel degradation phenomenology. The present paper reviews the updated knowledge on the phenomenology of the fuel degradation, focusing mainly on the BWR fuel assembly degradation at the macroscopic scale and that of the individual interactions at the meso-scale. Oxidation of boron carbide (B
C) control rods potentially generate far larger amounts of heat and hydrogen under BWR accident conditions. All integral tests with BC control rods or control blades have shown early failure, liquefaction, relocation and oxidation of BC starting at temperatures around 1250
C, well below the significant interaction temperatures of UO
-Zry. These interactions or reactions potentially influence the progress of fuel degradation in the early phase. The steam-starved conditions, which are being discussed as a likely scenario at the FDNPS accident, highly influence the individual interactions and potentially lead the fuel degradation in non-prototypical directions. The detailed phenomenology of individual interactions and their influence on the transient and on the late phase of the severe accidents are also discussed.
Sato, Yuki; Murakami, Hiroyuki*; Shimaoka, Takehiro*; Tsubota, Masakatsu*; Kaneko, Junichi*
Japanese Journal of Applied Physics, 55(4), p.046401_1 - 046401_5, 2016/04
Times Cited Count：4 Percentile：19.99(Physics, Applied)We investigated the performance of a charged particle detector fabricated using single-crystal diamond grown by chemical vapor deposition. The detector was able to identify four different 
Am 
-particle energies (5.389, 5.443, 5.486, and 5.545 MeV) because of its superior intrinsic energy resolution of 
0.4% (full width at half maximum). The charge collection efficiency inside the diamond crystal was 98% for both electrons and holes. The diamond detector also exhibited no significant degradation in terms of pulse height spectra and energy resolution during operation for more than 100 h in the case of mainly electron drift inside the diamond crystal. In contrast, the shapes of the pulse height spectra measured under hole drift condition deteriorated due to the polarization phenomenon.
Takase, Kazuyuki; Ose, Yasuo*; Yoshida, Hiroyuki; Akimoto, Hajime; Aoki, Takayuki*
Kashika Joho Gakkai-Shi, 25(Suppl.1), p.435 - 436, 2005/07
no abstracts in English
Omori, Shunzo
Sangyo To Denki, (629), p.1 - 2, 2005/02
no abstracts in English
Asakura, Nobuyuki
Plasma Physics and Controlled Fusion, 46(12B), p.B335 - B347, 2004/12
Times Cited Count：18 Percentile：51.27(Physics, Fluids & Plasmas)Particle control of the main plasma density and exhaust of impurities ions have been demonstrated using the divertor pumping under saturated divertor condition. In JT-60U, ELMy H-mode operation was recently extended to 30s (with NB heating of 8-14 MW). Total number of injected particles reached (1-4)x1023 to maintain high densities. During the long pulse ELMy H-mode of JT-60U, gas puff rate was decreased from 15 to 3Pam3/s, while pumping rate was relatively constant of ~10 Pam3/s. Thus, the divertor plate was mostly saturated. It was found that 40-50% of the injected D was retained, which are comparable to Tore-Supra long pulse and JET high density ELMy H-mode pulse. Particle balance for long pulse and/or high density plasmas are discussed. Carbon flux generated by the chemical process was increased due to increase in the target temperature. Carbon generation and carbon ion emission were gradually increased in the outer leg of the divertor and the X-point. Shielding effect of the divertor was sustained and increment of the radiation power fraction was small in 30s.
Takei, Nahoko; Nakamura, Yukiharu; Tsutsui, Hiroaki*; Yoshino, Ryuji; Kawano, Yasunori; Ozeki, Takahisa; Tobita, Kenji; Iio, Shunji*; Shimada, Ryuichi*; Jardin, S. C.*
Plasma Physics and Controlled Fusion, 46(12), p.1815 - 1830, 2004/12
Times Cited Count：3 Percentile：9.99(Physics, Fluids & Plasmas)no abstracts in English
thin-film solar cells for space useKawakita, Shiro*; Shimazaki, Kazunori*; Imaizumi, Mitsuru*; Kuwajima, Saburo*; Yoda, Shinichi*; Oshima, Takeshi; Ito, Hisayoshi
Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.151 - 154, 2004/10
no abstracts in English
Takase, Kazuyuki; Yoshida, Hiroyuki; Ose, Yasuo*
Dai-23-Kai Nihon Shimyureshon Gakkai Taikai Happyo Rombunshu, p.121 - 124, 2004/06
no abstracts in English
Oyama, Hidenori*; Takakura, Kenichiro*; Nakabayashi, Masakazu*; Hirao, Toshio; Onoda, Shinobu; Kamiya, Tomihiro; Simoen, E.*; Claeys, C.*; Kuboyama, Satoshi*; Oka, Katsumi*; et al.
Nuclear Instruments and Methods in Physics Research B, 219-220, p.718 - 721, 2004/06
Times Cited Count：3 Percentile：24.89(Instruments & Instrumentation)no abstracts in English
Takase, Kazuyuki; Yoshida, Hiroyuki; Ose, Yasuo*; Kureta, Masatoshi; Tamai, Hidesada; Akimoto, Hajime
Proceedings of 5th International Conference on Multiphase Flow (ICMF 2004) (CD-ROM), 14 Pages, 2004/06
no abstracts in English
Ose, Yasuo*; Takase, Kazuyuki; Yoshida, Hiroyuki; Kano, Takuma; Kureta, Masatoshi; Akimoto, Hajime
Dai-41-Kai Nihon Dennetsu Shimpojiumu Koen Rombunshu, 2 Pages, 2004/05
no abstracts in English
Nakamura, Yukiharu; Tsutsui, Hiroaki*; Takei, Nahoko*; Shirai, Hiroshi; Sugihara, Masayoshi; Gribov, Y.*; Ozeki, Takahisa; Tobita, Kenji; Iio, Shunji*; Jardin, S. C.*
Journal of Plasma and Fusion Research SERIES, Vol.6, p.196 - 198, 2004/00
no abstracts in English
Ishii, Yasutomo; Azumi, Masafumi; Kishimoto, Yasuaki
Theory of Fusion Plasmas, ISPP21, p.213 - 226, 2004/00
no abstracts in English
Ishii, Yasutomo; Azumi, Masafumi; Kishimoto, Yasuaki; Leboeuf, J. N.*
Nuclear Fusion, 43(7), p.539 - 546, 2003/07
Times Cited Count：26 Percentile：61.38(Physics, Fluids & Plasmas)no abstracts in English
Takase, Kazuyuki; Yoshida, Hiroyuki; Ose, Yasuo*; Tamai, Hidesada; Akimoto, Hajime
Dai-22-Kai Nihon Shimyureshon Gakkai Taikai Happyo Rombunshu, p.85 - 88, 2003/06
no abstracts in English
