DYNAMIC BEHAVIOR OF NATURAL-CIRCULATION S TEAM-GENERATORS

The article includes methods for the numerical simulation of instation ary operational conditions of natural-circulation steam generators. Ma thematical models am presented for the description of the dynamic beha viour of the drum, or the distributor and the collector, respectively, and of the non-adiabatic pipe flow. The numerical handling of the pip e flow, leading to a system of partial differential equations, is carr ied out by the explicit ''up-wind '' method. The ordinary differential equations, describing the distributor and the drum, are discredited b y an explicit differences methods. The result of the simulation of a w arm start of a natural-circulation steam generator is discussed extens ively.