Effect of Sintering on the Resuspension of Multilayer Graphite Particle Deposits in High-Temperature Gas-Cooled Reactors

The resuspension of deposited graphite particles in high-temperature gas-cooled reactors (HTGRs) under specific accident conditions has attracted considerable attention due to its critical connection with source terms. However, nearly all related studies have overlooked the effects of long-term high-temperature sintering after particle deposition, which could have a significant impact by changing the strength of particle-particle and particle-wall connections and lead to an overestimation of graphite dust resuspension in accident scenarios. In this work, we conduct an experimental study to quantitatively evaluate the effect of sintering on the resuspension behavior of graphite particles, combined with the rock’n’roll model for theoretical analysis. Meanwhile, the resuspension process is recorded with a high-speed camera. The results showed that sintered particles exhibit a higher friction velocity threshold for resuspension compared to their unsintered counterparts, with the effect amplified by increased sintering temperature and duration, particularly for larger particles. The friction velocity significantly increases (up to ~80%) after 9 h of sintering. The new resuspension curve can still be fitted to the rock’n’roll model by adjusting the effective surface energy, which shows an Arrhenius-type dependence on the sintering temperature. This preliminary study suggests that incorporating the sintering effect could significantly lower the estimated aerosol source term for HTGRs.