Prediction and Mitigation of Erosive-Corrosive Wear in Secondary Piping Systems of Nuclear Power Plants,

摘要

The report presents equations and parametric curves to predict erosive-corrosive wear rates in low carbon steel secondary piping systems of nuclear power plants. Two mechanisms causing the wear are identified and analytic expressions to predict the wear are presented. One mechanism, wear due to oxide dissolution, is present in single and two-phase flow lines; the other, wear by droplet impact induced fatigue, is only applicable for two-phase flows. Parametric curves are presented to predict the dissolution wear as a function of temperature, pH and characteristic (friction) velocity. An algebraic expression is used for droplet impact wear predictions as a function of superficial gas velocity and thermodynamic quality. Four mitigation strategies incorporated into the models (alloying, pH increase, moisture removal and velocity decrease) are introduced and the effectiveness of each is discussed. The models' wear predictions are not expected to be quantitatively exact, but should yield accurate qualitative rankings of systems susceptible to erosive-corrosive damage.