During the power uprate process significant consideration must be given to analysis and assessment of changes in flow acceleration corrosion (FAC) rate. Any change in reactor power output directly influences all parameters, which control piping components' FAC speed. Susceptibility to FAC is influenced by number of factors; their alteration may result in increased FAC rate in certain parts of the secondary circuit, whereas FAC speed in other sections may drop. It all depends on specific system modifications, equipment changes etc. Experience with power uprate in some NPPs show that the FAC rate need not necessarily correspond with the theoretical expectations. The paper evaluates influence of planned reactor heat power uprate in the range of 105-109% to the FAC rate of the secondary piping components in NPP in the Czech republic and Slovakia. The individual parameters in the main secondary piping systems of VVER-type NPP are evaluated, together with FAC rate changes in these lines.