Low alloy steel is being considered as a candidate material for underground waste storage. The performance of this barrier is heavily dependent upon the integrity of the oxide layer formed on this material in the underground environment. In view of the long timescale, numerical simulation of the oxide layer behaviour is one of the only feasible options for long term performance prediction.
A classical point defect model for a magnetite oxide film on iron has been explored. Transport occurs through oxygen vacancies and metal interstitials by diffusion and migration. At the film’s interfaces metal interstitials and oxygen vacancies are being produced and annihilated.
A spinel point defect model for a magnetite oxide film on iron has been developed. In the film, transport occurs through oxygen, FeII and FeIII vacancies by diffusion and migration. At the film’s interfaces FeII, FeIII and oxygen vacancies are being produced and annihilated. This model takes the magnetite structure of the film into account.
The classical point defect model has been applied to iron in a borate buffer solution at pH 8.4 based on available data using both MS-Excel and Comsol Multiphysics.
Approximate kinetics control criteria have been derived for both models.
|Number of pages
|Published - Mar 2010
|Studiecentrum voor Kernenergie