Transport Processes by Localized Corrosion in Steam Generator Crevices

Abstract The conditions under which it is possible to neglect the change of the saturation of the liquid in SG crevices were obtained. It has been shown that in the entry region of the SG crevices the liquid velocity can be described by a linear function. The calculations show that the species concentrations and the potential reach quasi - asymptotic limits throughout the cavity; the limits are determined by the available superheat. After the attainment of these limits, a constant crevice corrosion rate is predicted. The condition was determined whereby the transport processes in the external environment determine the corrosion current density in the crevice. Due to the low value of conductivity and a relatively large crevice width assumed in the calculations, this condition can actually be fulfilled, if the cathodic processes in the crevice do not essentially reduce the current, which flows out of the crevice.