EVALUATION OF HYDRAULIC FACTORS AFFECTING FLOW ACCELERATED CORROSION AND ITS VERIFICATION WITH POWER PLANT DATA

摘要

Flow Accelerated Corrosion (FAC) is well known as a complex phenomana of hyraulics and electro-chemicals. Among the two, this study focused on the hydraulic factors affecting FAC. FAC experiments with small rectangular flow duct were conducted in PWR condensate condition. Flow field for the experiment was calculated with numerical simulation using LES (Large Eddy Simulation) turbulence model. From both experimental and numerical results, new model of mass transfer coefficient, as the essential parameters of hydraulics, was proposed considering local turbulent velocity, so as to evaluate the effect of eccentric flow on FAC. To verify the applicability of the model, FAC plant data of actual PWR (Pressurized Water Reactor) condensate line (146 degC) and BWR (Boiling Water Reactor) condensate line (35 degC) were referred. Mass transfer coefficients for each pipe lines were calculated from flow numerical analysis. The new proposed model showed good correlation with the data of FAC thinnng rate, and its applicability was confirmed. In addtion, comparing the two plant cases, electro-chemical effect could be estimated as a similar level, which suggests the possibility of low-temperature FAC in BWR condensate lines.