| Abstract: |
| The prediction of long-term corrosion behavior of repository waste canister is needed to ensure that its physical integrity will not be affected during its expected life time. One particular corrosion phenomena that could affect the canister made in austenitic stainless steel is pitting corrosion. It is a localized corrosion form by which cavities or holes are produced in the material. By understanding these processes, it will be possible to better fight the degradation of the materials and to select the most suitable protection method.
One of the approaches used to determine the long-term behavior of metal structures is based on the development of models using a deterministic approach that presupposes a description of the metal-environment systems by a complex system of physico-chemical equations.
The aim of this work is to model and simulate the pit propagation in stainless steel taking into account the complexity of its development (anodic dissolution, diffusion, migration and reactions). From a mathematical point of view, this problem
can be identified as a Stefan problem involving a convection-reaction-diffusion system.
Due to the complexity of the problem, we chose to start in one-space dimension to create a pertinent and efficient numerical scheme which will allow us to simulate the time evolution of pit propagation. The model will be developed step by step to gradually integrate the complexity of the chemical system, first by taking the diffusion and migration (convection term related to the potential difference) into account and then including the reaction term in the partial differential equation system.
In this talk, we will present the mathematical modeling of pit propagation in space dimension one and we will also prove the stabilization of the solution to a self-similar profile in a very simplified context in a joint study with Y. Miyamoto.
CEA, Orano Cycle and EDF are gratefully acknowledged for co-financing the study. |
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