In research of 18F monitoring system, the determination of 18F transit efficiency is a key problem. Due to the reason of experiment location which is currently limited to using theory calculation. The article study the transport properties of the 18F from the primary circuit to the sampling channel after 55/19 steam generator tube leaking by analysis of the thermo-hydraulic characteristics and the structure of the steam generator, and select five particle size of dust as the operation conditions, then this wi...