Modeling of air region height in the casting process for preparing UO2 kernels

In the process of preparing UO2 kernels, the casting solution is emitted from the nozzle into an air region to obtain droplets with good sphericity. Before the droplets enter the aqueous ammonia solution, they pass through an ammonia gas atmosphere for prehardening. The distance from the nozzle to the ammonia gas section is the height of the air region. In this paper a mathematical model was established to calculate the optimized height of air region, which is about 11.4 cm. Effects of nozzle number, solution density and inner diameter of nozzle on the height are discussed. The effective method for reducing height of air region is to increase the inner diameter of nozzle.