Predictive modelling of the corrosion rate of carbon steel focusing on the effect of the precipitation of corrosion products

Abstract

In the frame of conceptual design for the long-term management of high level radioactive waste defined by Andra (France), it is assumed that carbon steel (C-Steel) overpack would be mainly affected by general corrosion. As it is widely accepted that precipitation of a corrosion product layer (CPL) can limit the corrosion rate, the aim of this work is to simulate the growth of a thick FeCO3 CPL and its impact on the evolution of the corrosion rate. We use a 1D finite element method numerical model based on the resolution of Nernst–Planck equation in free potential conditions. Two numerical models of the evolution of the corrosion rate of low alloy steel in anoxic conditions are developed. These models take into account the growth of a porous CPL assuming either a constant and homogeneous porosity or a varying and heterogeneous porosity and results are compared to experimental data. This paper is part of a supplement on the 6th International Workshop on Long-Term Prediction of Corrosion Damage in Nuclear Waste Systems.