Simulations of the dust behavior in the sampling and dust filters in the primary loop of HTR-10

Abstract

Abstract The radioactive dust in the primary loop of high-temperature gas-cooled reactors (HTGRs) is one of the key challenges to operational safety, particularly in the event of depressurization accidents. To study the behavior of radioactive dust in the primary loop of the HTR-10 reactor, a sampling loop (equipped with a sampling filter) was designed and built in its helium purification system, parallel to the dust filter. Two experiments were conducted using this sampling loop in 2015. The concentrations, particle size distribution of the dust, and typical solid fission and activation products detected in the dust were investigated (Xie et al., 2017). In this paper, we presented the γ spectra of the three filter elements from the second experiment as well as those of the unused filter elements, for comparison. To further analyze the characteristics of the dust motion during the sampling experiment, the computational fluid dynamics (CFD) method was used to simulate the flow field in the experimental system. Subsequently, we analyzed the transport and deposition behaviors of the dust, and discussed the effects of the diameters and flow rates of the particles on the behavior of the dust. Our calculations indicated that different particle deposition characteristics corresponded to different filters. We noticed that for the horizontal sampling filter, small particles were more prone to deposit on the first filter, whereas the large particles were more likely to deposit on the bottom surface. Moreover, as the mass flow increased, the effect of gravity decreased. For the vertical dust filter, we noticed that the distance between the deposition location of the particles and inlet increased, while the residence time decreased as the particle size increased. Moreover, the distance between the deposition location and inlet for the small particles increased, while the incidence of the large particles decreased as the mass flow increased. These simulation results could prove valuable for the experimental research of the radioactive dust of HTR-10.