Controllable preparation of SiC-coated U3O8 nuclear fuel microspheres in microfluidics
ATF(accident tolerant fuel)is considered to be a new advantage nuclear fuel system with greater safety,and the coated nuclear fuel microspheres are important foundational materials used in the preparation of accident tolerant nuclear fuel.Based on the precise and controllable preparation of double emulsion droplets with microfluidic technology,a microfluidic preparation method for SiC-coated U3O8 nuclear fuel microspheres was proposed,using Urania sol as core phase fluid,silicon carbide/n-butanol dispersion as shell phase fluid,and dimethylsilicon oil as the external continuous phase.The effects of the physical properties of each phase fluid on the formation of monodispersed droplets were analyzed in detail.Also,the effects of the volatilization rate of the core and shell phases on the matched volume shrinkage of the core and shell phases during the solidification process of the prepared double emulsion droplets were studied.The results show that the increase in fluid separation force due to the increase in fluid viscosity can effectively improve the formation of monodispersed droplets.Butanol has a volatilization rate similar to that of water in the range of 40-90 ℃,making it an ideal dispersion medium,and a stable preparation of SiC-coated U3O8 microspheres can be achieved by using SiC/butanol dispersion with mass fraction of 5％SiC as shell phase fluid.
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