Study on the resuspension of graphite dust based on the Rock'n'Roll model

Abstract

The resuspension characteristics of graphite dust in a high temperature gas-cooled reactor significance impact the source terms in the reactor safety analysis. The present academic study analyzes resuspension behavior of graphite dust, including the effects of the distribution of the independent variables between the particle and substrate adhesion, the particle diameter and the time for the resuspension characteristics of graphite dust based on the Rock'n’Roll model. The results indicated that the distribution of the independent variables for the adhesion has an important influence on the resuspension characteristics of the particles and that the Biasi fitting distribution gives a better fit to the experimental data. Particles with larger mean values of adhesion between the particle and the substrate are less prone to resuspension. Hence, a larger standard deviation σa' will overestimate the resuspension fraction for a low-speed case and underestimate the resuspension fraction in the high-speed region. Graphite dust particles with larger particle diameters are more likely to be resuspended and have a greater resuspension fraction at the same friction velocity. For the conditions matching the operating parameters of HTR-10, the threshold friction velocity that enables 0.5 μm graphite dust particles to resuspend is 5.76 times larger than that of 5 μm particles and 16 times larger than that of 10 μm particles. In addition, these results also showed that the graphite dust particle fraction changes with time and can be divided into short-term and long-term effects. The critical time between the short-term and long-term effects decreases with increasing helium velocity and particle diameter.