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平成30年9月博士課程修了予定者論文発表会 原子核工学専攻

平成30年6月25日(月) 会場: 先導原子力研究所  北2号館6F会議室

開始時刻/
終了時刻
発表者氏名 指導教員 論  文  題  目
13:00
15:00
San Shwin
IGP-(C)
木倉宏成
赤塚 洋
Study on the Influence of the Inlet Swirling Flow in a Double and Triple Elbow using Phased Array UVP
Turbulent flow structure was visualized downstream of the double and triple elbow layout using Phased Array Ultrasonic Velocity Profiler (Phased Array UVP). In addition, the experimental results were performed to validate CFD numerical simulation. The objective is to understand the complexity of the turbulent flow under the condition of swirling inlet and without swirling inlet. Furthermore, the reattachment point of secondary swirling flow downstream of the double and triple elbow was observed. To generate inlet swirling flow, the rotary type swirling generator is installed upstream of the elbow layout. The water flowed in the turbulent flow condition at Reynolds number Re = 1 × 104 and the inlet swirl intensity was S = 1. Phased Array UVP technique was applied to measure two-dimensional velocity of the fluid and to find out the flow separation point and reattachment point. From the numerical simulation results, the axial velocity contour and the tangential and radial velocity field were visualized in the cross-sectional plane downstream of double and triple elbow pipe layout in the cross-sectional plane of pipe.

 

平成30年6月25日(月) 会場: 先導原子力研究所  北2号館6F会議室

開始時刻/
終了時刻
発表者氏名 指導教員 論  文  題  目
15:00
17:00
Zhou Jiaju
IGP-(C)
木倉 宏成
赤塚 洋
Study on Joule-heating Flow and Diffusion Flow in Glass Melter Models.
Flow behavior was observed in a simplified model cavity of a multiphase High Level Liquid Wasted (HLLW) reprocessing glass melter. In the glass melter, a Joule-heating flow occurred because the voltage was applied between the electrodes set on the upper side. A 2-D glass melter shape model cavity named sloping bottom cavity was applied to observe this Joule-heating flow. To know the flow behavior in the cavity, flow behavior was measured by Ultrasound Velocity Profiler (UVP) method and Particle Image Velocimetry (PIV) method. The flow was also simulated by original CFD code. The flow behavior in glass melter is too complicated by interfering of flow field, thermal field and magnetic Field. Hence, finite element analysis code, GSMAC-FEM, which applies coupled solution three fields, was utilized to simulate the molten glass. In addition, a diffusion flow also occurred due to the HLLW feeding. To understand the flow diffusion, the injected fluid concentration was measured using an Electric Resistance Tomography (ERT) technique at the top, middle and bottom levels in a simplify cavity. The flow behavior also simulated by A commercial CFD code fluent using Volume of Fluid (VOF) model. The experimental results of two flows were also used to validate the CFD code.

 

平成30年6月29日(金) 会場: 先導原子力研究所 北1号館1階会議室

開始時刻/
終了時刻
発表者氏名 指導教員 論  文  題  目
10:00
12:00
Hoang Van Khanh
IGP-(A)
小原 徹
松本義久
Design Concepts of Small CANDLE Reactor with The Melt-Refining Process
The CANDLE (Constant Axial shape of Neutron flux, nuclide densities and power shape During Life of Energy producing reactor) burnup strategy has been successfully applied to fast reactors. Using the CANDLE burning strategy in a fast reactor reveals many advantages, but maintaining the material integrity up to high burnup is one of the major issues addressed in the reactor design. Using the melt-refining process is a promising solution to overcome the material integrity issue. The objective of this study is to show design concepts of small CANDLE reactor with the melt-refining process. A 300 MWt lead-bismuth-eutectic cooled reactor is designed. The reactor utilizes the metallic fuel (U-10 wt. % Zr) of the natural uranium as fresh fuel and uses lead bismuth eutectic as coolant. The burnup performance of the reactor with the melt-refining process is investigated in comparison with that of a conventional CANLDE reactor. For the core with the melt-refining process, the three bounding scenarios are evaluated: all actinides are recovered, 10 % or 5 % of all actinides are not recovered. The thermal-hydraulic analysis for the hottest sub-channel in the equilibrium state is performed to determine whether the core design satisfies the design constraints. In the scenario of which all actinides are recovered, the calculated results showed that the burnup performance of the small CANDLE reactor increases remarkably. The improvement of the burnup performance can be maximized by optimizing the melt refining regions and the core design parameters. For the scenario of which several percentages of the actinides are not recovered, it is found that the reactor can behave like the CANDLE burnup strategy. The calculated results show that the compensating for the fuel losses results in requiring additional uranium to make up fuel, reducing fuel burnup. By reusing the discharged fuels, the fuel waste is reduced, the fuel utilization is improved.

 

平成30年7月4日(水) 会場: 先導原子力研究所 北2号館6階会議室

開始時刻/
終了時刻
発表者氏名 指導教員 論  文  題  目
9:00
11:00
Mark Dennis Anak Usang 千葉 敏
相楽 洋
Study on mechanisms of nuclear fission by Langevin equation
Nuclear fission is still a complex phenomenon of nuclear physics due to its nature as a large-amplitude collective motion.  In this study, we studied fission mechanisms of actinide nuclei by Langevin equation.  In the past researches, number of degree-of-freedom to express nuclear shape during fission was restricted to 3 at most, and macroscopic transport coefficients were employed.  We have improved the model to incorporate microscopic transport coefficients based on linear response theory, which can account of the single-particle structure and pairing effects.  Such transport coefficients depend on nuclear temperature and affects the Langevin trajectory, and make agreement of the theoretical prediction with experiment better.  Then, a 4-dimensional Langevin model was developed, where the restriction that 2 fission fragments have the same deformation was discarded.  This made it possible to describe both systematical trends and anomalies in mass and TKE (total kinetic energy) distributions of fission fragments drastically better than 3D Langevin.  It was also found that there is a quite complicated correlations between the deformations of 2 fragments.  These findings gave us new insights into the mechanisms of nuclear fission.