Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Wada, Yuki; Le, T. D.; Satou, Akira; Shibamoto, Yasuteru; Yonomoto, Taisuke
Journal of Nuclear Science and Technology, 57(1), p.100 - 113, 2020/01
Times Cited Count：7 Percentile：56.42(Nuclear Science & Technology)Satou, Akira; Wada, Yuki; Shibamoto, Yasuteru; Yonomoto, Taisuke
Nuclear Engineering and Design, 354, p.110164_1 - 110164_10, 2019/12
Times Cited Count：9 Percentile：65.60(Nuclear Science & Technology)JAEA has conducted a series of experimental researches on the Post-boiling transition heat transfer, transient critical heat flux and rewetting for BWRs. Experimental data bases covering the anticipated operational conditions was developed; the significance of the precursor cooling was identified. This paper presents approaches of the present research focusing on the anticipated transient without scram, effects of the spacer and physical understanding of the phenomena for development of mechanistic model together with promising results obtained so far.
Wada, Yuki; Satou, Akira; Shibamoto, Yasuteru; Yonomoto, Taisuke; Sagawa, Jun*
Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.4518 - 4531, 2019/08
Liquid film detection under boiling transition (BT) condition is one of the important issues to develop models on dry out and rewet including physical characteristics of liquid film behavior. Although a heater surface temperature has been often used in previous studies to detect the position of liquid film front, it is difficult to accurately identify the position from the temperature measurement. Therefore, we are developing a nonintrusive measurement technique for detecting thin liquid film thickness under BT and rewet condition using ultrasound. In this study, we focus on high accuracy measurement for liquid film thinner than 0.1 mm by using high frequency ultrasound of 15 MHz and developing a signal processing method. Liquid film measurement results were found to agree with liquid film thickness correlations. Based on a comparison with constant current method, it is concluded that the present technique gives more reasonable liquid film thickness than constant current method.
Wada, Yuki; Le, T. D.; Satou, Akira; Shibamoto, Yasuteru; Yonomoto, Taisuke
Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 10 Pages, 2018/07
Satou, Akira; Wada, Yuki; Le, T. D.; Shibamoto, Yasuteru; Yonomoto, Taisuke
Proceedings of ANS International Conference on Best Estimate Plus Uncertainties Methods (BEPU 2018) (USB Flash Drive), 12 Pages, 2018/00
Experiments were performed under the condition of AOO for BWRs to obtain Post-BT heat transfer rate, deposition rates of liquid droplets, and the rewetting behavior after the core dryout. Rewetting behavior was analytically investigated and a relation among the rewetting velocity, the hot wall temperature, and the heat transfer rates in the precursory cooling and wetted regions were obtained. In addition, experiments simulating the condition of ATWS were newly performed with simulated ferrule spacers especially to investigate the spacer effect. It was found that the heat transfer rates were enhanced by the spacers, which were compared with existing prediction models for the validation. The spacers also appeared to increase the rewetting velocity slightly. Since the precursory cooling was found to play an important role on the rewetting behavior through the series of prior experiments, new experiments are conducted focusing on the precursory cooling. In those experiments, the behaviors of liquid film and droplets around the rewetting front were observed to investigate the mechanism of the precursory cooling.
Wakeda, Masato*; Tsuru, Tomohito; Koyama, Masanori*; Ozaki, Taisuke*; Sawada, Hideaki*; Itakura, Mitsuhiro; Ogata, Shigenobu*
Acta Materialia, 131, p.445 - 456, 2017/06
Times Cited Count：37 Percentile：83.13(Materials Science, Multidisciplinary)Most of the solute species show a significant interaction with the dislocation core, while only several solute species among them, such as Si, P, and Cu, significantly lower the Peierls potential of the screw dislocation motion. A first-principles interaction energy with the "Easy-core" structure excellently correlates with the change in the 
-surface caused by solute atoms (i.e., chemical misfit). We show the availability of the interaction energy to predict the effect of each species on macroscopic critical resolved shear stress (CRSS) of the dilute Fe alloy. The CRSS at low and high temperature for various alloys basically agree with experiment CRSS. These results provide a novel understanding of the interaction between a screw dislocation and solute species from the first-principles.
Sakanaka, Shogo*; Ago, Tomonori*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; Harada, Kentaro*; Hiramatsu, Shigenori*; Honda, Toru*; et al.
Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.205 - 207, 2008/06
Future synchrotron light sources based on the energy-recovery linacs (ERLs) are expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation. Our Japanese collaboration team is making efforts for realizing an ERL-based hard X-ray source. We report recent progress in our R&D efforts.
Wada, Yuki; Sagawa, Jun*; Satou, Akira; Shibamoto, Yasuteru; Yonomoto, Taisuke
no journal, ,
no abstracts in English
Wada, Yuki; Sagawa, Jun*; Hirose, Yoshiyasu*; Satou, Akira; Shibamoto, Yasuteru; Yonomoto, Taisuke
no journal, ,
In this study, ultrasound liquid film thickness measurement system is developed to measure thin liquid film thickness using a piezo element of 15 MHz and an original driving circuit by the pulse-echo method. Since our system is higher frequency than previous study, we can observe individually multi-reflected signals in the liquid film until 0.2 mm thickness and it is indicated that high accuracy liquid film thickness measurement will be possible less than 0.2 mm thickness.
Le, T. D.; Wada, Yuki; Shibamoto, Yasuteru; Yonomoto, Taisuke
no journal, ,
Wada, Yuki; Sagawa, Jun*; Satou, Akira; Shibamoto, Yasuteru; Yonomoto, Taisuke
no journal, ,
no abstracts in English
Wada, Yuki; Satou, Akira; Shibamoto, Yasuteru; Yonomoto, Taisuke
no journal, ,
no abstracts in English
Onodera, Naoyuki; Shimokawabe, Takashi*; Idomura, Yasuhiro; Kawamura, Takuma; Hasegawa, Yuta; Ina, Takuya; Inagaki, Atsushi*; Hirano, Kohin*; Shimose, Kenichi*; Oda, Ryoko*; et al.
no journal, ,
The project goal is to realize real-time wind prediction in urban areas by assimilating observed data into real-time wind simulations on GPU supercomputers. In FY2023, a data assimilation method based on the Local Ensemble Transform Kalman Filter (LETKF) was applied to CityLBM in order to reproduce local wind conditions with high accuracy. We validated the data assimilation method for two-dimensional forced isotropic turbulence. It was confirmed that the LETKF with 64 ensembles provides the same levels of accuracy with 1/16th of the coarse observation points compared to the nudging method. In addition, it was confirmed that the application of LETKF can reproduce the phase of the Kalman vortex with high accuracy in the verification of the flow around a three-dimensional square cylinder.
Ishigaki, Masahiro; Abe, Satoshi; Wada, Yuki; Shibamoto, Yasuteru; Yonomoto, Taisuke
no journal, ,
no abstracts in English
