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Large-Scale Direct Simulations on Complex Two-Phase Flow Behavior in Nuclear Reactors |
Kazuyuki Takase, Hiroyuki Yoshida, Takeharu Misawa
Japan Atomic Energy Agency
Complex two-phase flow behavior in a fuel bundle of an advanced light water reactor was analyzed numerically with three-dimensional large-scale direct simulations. A new two-phase flow analysis method was developed. It can precisely predict the interface between the liquid and gas phase in two-phase flow by using the interface tracking method. Although extraordinary computational resources are required to achieve large-scale direct simulations, the Earth Simulator (ES) in Japan was capable of such a request. The ES is a highly parallel vector supercomputer with 10 TB of main memory and 40 TFLOPS of theoretical performance. Conventional analysis methods need composition equations/empirical correlations based on experimental data. When the experimental data are lacking, therefore, it is difficult to obtain high prediction accuracy. Then, the direct simulations were chosen as a first step to establish ‘Design by Analysis’. Figure 1 shows a bird’s-eye view of the actual advanced light-water reactor design. Figure 2 shows a fuel bundle consisting of a hexagonal fuel channel and 37 fuel rods. Figure 3 shows the predicted bubbly flow dynamics in a fuel bundle and Figure 4 shows the liquid film flow dynamics on the fuel rods. The authors are developing the advanced numerical method in which two-phase flow dynamics in nuclear reactors can be reproduced on the computer.
Contact
Kazuyuki Takase
Japan Atomic Energy Agency (JAEA)
2-4 Shirakata, Tokai-mura, Ibaraki-ken, 319-1195
Japan