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Sun, G.*; Zhan, Y.*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Uchibori, Akihiro; Okano, Yasushi
Experimental Thermal and Fluid Science, 151, p.111095_1 - 111095_15, 2024/02
Saha, P. K.; Harada, Hiroyuki; Yoneda, Hitoki*; Michine, Yurina*; Sato, Atsushi*; Shibata, Takanori*; Kinsho, Michikazu
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.59 - 63, 2023/11
Tei, C.; Otaka, Masahiko; Kuwahara, Daisuke*
Chemical Physics Letters, 829, p.140755_1 - 140755_6, 2023/10
We were able to detect the nuclear magnetic resonance (NMR) signal of a liquid sodium clinging to the interface of solid metal particles for the first time. In this study, we confirmed the difference in the relaxation times due to the difference in the interactions between liquid sodium and metal particles suspended in the liquid sodium. It was found that the surface of the micro titanium particles and liquid metallic sodium interact physically, not chemically.
Sun, G.*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Uchibori, Akihiro; Okano, Yasushi
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 8 Pages, 2023/05
When liquid sodium leaks as a liquid jet from piping in a sodium-cooled fast reactor, the jet impinges with structures to produce splashing droplets which can cause significant combustion. According to previous studies on circular nozzles, the amount of splash is affected by the state of the jet at the moment of impingement. In the present work, a nozzle with a sudden contraction in the cross-sectional area was designed to reproduce a supposed pipe leakage, and the breakup behavior of jet discharged from this nozzle was observed. The result shows that the breakup of jet was accelerated until the jet transformed into a particularly stable state when the jet velocity exceeded a certain value. Once the jet has transformed, it will not turn back unless turning down the flow rate to a very low value. The stable jet after the transformation has a longer breakup length than that before the transformation in the same flow rate.
Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Yoneda, Hitoki*; Michine, Yurina*; Sato, Atsushi*; Shibata, Takanori*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.272 - 276, 2023/01
Collaborative Laboratories for Advanced Decommissioning Science; The University of Electro-Communications*
JAEA-Review 2022-029, 37 Pages, 2022/11
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2021. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2019, this report summarizes the research results of the "Semiautonomous remote-control technology of an articulated mobile robot to recover from stuck states" conducted from FY2019 to FY2021. Since the final year of this proposal was FY2021, the results for three fiscal years were summarized. The purpose of this work is to establish a recovery method of an articulated mobile robot from stuck states. In this work, a control method of the robot to recover from stuck states by using redundancy of the system is proposed. In addition, we develop two interfaces. One is a display interface as an operator can understand the situation of the robot and surrounding terrain, and the other is a control interface to provide a target motion using the proposed control method.
Sun, G.*; Zhan, Y.*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Uchibori, Akihiro; Okano, Yasushi
Proceedings of 29th International Conference on Nuclear Engineering (ICONE 29) (Internet), 6 Pages, 2022/08
When a liquid sodium leakage accident occurs in a sodium-cooled fast reactor, the injected sodium collides with structures to produce splashing droplets, which can result in a violent combustion. According to previous studies on circular nozzles, the amount of splash is affected by the state of the jet at the moment of impact. However, the outlet shape of damaged area is hardly to be circular; and meanwhile it influences the flow pattern of jet a lot. Considering about this, in the present work, high-speed cameras were used to observe the jet discharged from oval nozzles vertically downward to investigate the falling process of the jet. The result shows that surface wave appears on the jet and within a certain range of flow velocity it can be observed obviously, meanwhile accelerate the breakup of jet.
Collaborative Laboratories for Advanced Decommissioning Science; The University of Electro-Communications*
JAEA-Review 2021-025, 33 Pages, 2021/11
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2019, this report summarizes the research results of the "Semi- autonomous remote-control technology of an articulated mobile robot to recover from stuck states" conducted in FY2020. The purpose of this work is to establish a recovery method of an articulated mobile robot from stuck states. In this work, a control method of the robot to recover from stuck states by using redundancy of the system is proposed. In addition, we develop two interfaces. One is a display interface as an operator can understand the situation of the robot and surrounding terrain, and the other is a control interface to provide a target motion using the proposed control method. Finally, the effectiveness of them is demonstrated by experiments using an actual robot.
Saha, P. K.; Harada, Hiroyuki; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Shibata, Takanori*; Kinsho, Michikazu
Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.656 - 660, 2021/10
Zhan, Y.*; Sun, G.*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Takata, Takashi
Experimental Thermal and Fluid Science, 126, p.110402_1 - 110402_8, 2021/08
Times Cited Count:5 Percentile:61.49(Thermodynamics)Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Liu, Y.*
JPS Conference Proceedings (Internet), 33, p.011025_1 - 011025_7, 2021/03
Zhan, Y.*; Kuwata, Yusuke*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Takata, Takashi
Experimental Thermal and Fluid Science, 120, p.110249_1 - 110249_12, 2021/01
Times Cited Count:5 Percentile:73.29(Thermodynamics)Collaborative Laboratories for Advanced Decommissioning Science; The University of Electro-Communications*
JAEA-Review 2020-025, 34 Pages, 2020/12
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2019. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2019, this report summarizes the research results of the "Semiautonomous Remote-control Technology of an Articulated Mobile Robot to Recover from Stuck States". The purpose of this work is to establish a recovery method of an articulated mobile robot from stuck states. In this work, a control method of the robot to recover from stuck states by using redundancy of the system is proposed. In addition, we develop two interfaces. One is a display interface as an operator can understand the situation of the robot and surrounding terrain, and the other is a control interface to provide a target motion using the proposed control method. Finally, the effectiveness of them is demonstrated by experiments using an actual robot.
Harada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Shibata, Takanori*; Kinsho, Michikazu
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.441 - 445, 2020/09
The high-intensity proton accelerator adopts a charge exchange injection scheme, which injects with exchanging from negative Hydrogen ion to proton by using carbon foil. This scheme is destructive-type method by using the foil and can accumulate high intensity proton beam. However, the uncontrolled beam losses by scattering at the foil and the foil breaking by the beam collision are a key issue of high-intensity proton accelerator. In order to realize higher intensity, new injection scheme of non-destructive type is needed instead of the foil. We newly propose laser stripping injection scheme by using laser pulse. We plan proof of principle experiment at J-PARC and are developing the laser system. In my presentation, we introduce the overview of laser stripping injection scheme and report the status of laser development.
Saha, P. K.; Harada, Hiroyuki; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Shibata, Takanori*; Kinsho, Michikazu
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.436 - 440, 2020/09
Zhan, Y.*; Kuwata, Yusuke*; Maruyama, Kiyotaka*; Okawa, Tomio*; Enoki, Koji*; Aoyagi, Mitsuhiro; Takata, Takashi
Experimental Thermal and Fluid Science, 112, p.109953_1 - 109953_8, 2020/04
Times Cited Count:9 Percentile:71.8(Thermodynamics)Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Sato, Atsushi*; Yoneda, Hitoki*; Michine, Yurina*
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.841 - 845, 2019/07
Zhan, Y.*; Oya, Naoki*; Enoki, Koji*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Takata, Takashi
Experimental Thermal and Fluid Science, 98, p.86 - 94, 2018/11
Times Cited Count:11 Percentile:65.34(Thermodynamics)Kuwata, Yusuke*; Zhan, Y.*; Enoki, Koji*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Takata, Takashi
Proceedings of 12th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-12) (USB Flash Drive), 10 Pages, 2018/10
This study aims improvement of safety analysis for sodium fire accidents in sodium-cooled fast reactors. In the experiment, effect of viscosity on liquid jet impact on solid surface was studied.
Zhan, Y.*; Oya, Naoki*; Enoki, Koji*; Okawa, Tomio*; Ohno, Shuji; Aoyagi, Mitsuhiro; Takata, Takashi
Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 6 Pages, 2017/07
It is important to set the amount of sodium droplet mechanistically for appropriate numerical evaluations of sodium leak and fire behavior in a sodium-cooled fast reactor plant. In the present work, fundamental experiments are performed to measure the splash ratio during the vertical water jet impact onto a horizontal wall. It is shown that the splash ratio can be correlated well as a function of the impact Weber number and dimensionless impact frequency.