Session: 08-08: Computational Fluid Dynamics (CFD) and Applications - VIII

Paper Number: 135739

135739 - The Influences of Key Factors on the Gas Diffusion in the Material Irradiation Tests Based on the Regulation of Gas Composition 

Abstract: 

Temperature is the key irradiation parameter, the vital segment of the irradiation test is to design the structure of irradiation device to make the specimen temperature meet the requirements. The main way to control the temperature of specimen in the irradiation device is to design the gas gap and adjust the composition of gas mixture to change the thermal conductivity of the gas. The gas is usually a mixture of helium and argon, during the irradiation test, a certain volume of argon is injected into the device to increase the irradiation test temperature or a certain volume of helium gas is injected into the device to decrease the irradiation test temperature. The study takes the annular gas gap of the typical material irradiation device as the research object to study the gas diffusion behavior by means of computational fluid dynamics (CFD). The study analyses the influence of key factors such as the type of the gas inflated, the volume and rate of the gas inflated and the width of gas gap on the gas diffusion behavior in the process of regulating gas composition. The results show that the helium will diffuse upward primarily, while the argon will deposit downward, the gas mixture will tend to mix evenly finally. The gas inflated forms vortexes at the entrance, which will trap the stationary gas in the device around the entrance. The volume and rate are the keys to influence the diffusion process, including the time taken to reach the stable state and the distribution of gas mixture in the stable state. The results indicate that the more the gas is inflated, the farther the gas diffuses, and the time taken to reach the stable state will be longer. Furthermore, the faster the gas is inflated, the larger the vortexes are formed at the entrance, and the stationary gas in the device around the entrance is trapped more vigorously, which will make the gas mixed with the original gas in the device more fully. The width of the gas gap decides the gas diffusion channel. The wider gas gap is benefit to the diffusion of the gas inflated, which will facilitate the gas to mix with the original gas in the device fully. Based on the research results, the transient response characteristics of the specimen temperature during the process of regulating gas composition can be further studied, which is conducive to the fine control of the irradiation test temperature.

Presenting Author: Yixiong Sun Nuclear Power Institute of China

Presenting Author Biography: Yixiong Sun, Nuclear Power Institute of China, engage in thermal-hydraulic research of nuclear reactors.

Authors:

Yixiong Sun Nuclear Power Institute of China
Wenhua Yang Nuclear Power Institute of China
Sheng Sun Nuclear Power Institute of China
Liang Zhang Nuclear Power Institute of China
Wenbin Zhao Nuclear Power Institute of China
Shuai Jin Nuclear Power Institute of China
Jin Lei Nuclear Power Institute of China
Jinkang Cheng Nuclear Power Institute of China