An Advanced Model for Long-Term Localized Corrosion of Copper
Notice bibliographique
Résumé
The Nuclear Waste Management Organization (NWMO) is responsible for the implementation of the Adaptive Phased Management (APM) plan, the federally-approved plan for the safe long-term management of Canada’s used nuclear fuel. 1 Under the APM plan, used nuclear fuel will ultimately be placed within a deep geological repository (DGR) in a suitable host rock formation. Part of evaluating the long-term performance and safety of the repository system is understanding the behavior of the copper-coated container with respect to localized corrosion. Even though localized corrosion is not expected in the DGR design system, there is still a need to develop a mathematical model for localized corrosion of copper. A 2-D axisymmetric time-dependent model for the localized corrosion of copper was developed using the concept of an Evans droplet. 2 The model accounts for three reversible electrochemical reactions on the metal surface (copper dissolution/plating, cuprous ion oxidation (Cu + ) /cupric ion (Cu 2+ ) reduction, and hydrogen (H 2 ) evolution/oxidation) and three irreversible electrochemical reactions (cupric ion reduction, oxygen (O 2 ) reduction, and hydroperoxyl ion (HO 2 - ) reduction). Dissolved cuprous ion reacts in a second chemical step to form the cuprous chloride (CuCl) salt film treated as a diffusion barrier, or it reacts to form the cuprous oxide (Cu 2 O) film that partially blocked the active area on the metal surface. The model also accounts for fifteen homogeneous reactions involving copper chloride complex, copper hydroxide complex, copper carbonate complex, and superoxide species. The associated equilibrium constants were obtained from PHREEQC thermodynamic software. 3 The mathematical model was developed using the finite-element method (COMSOL Multiphysics). The model includes coupled, nonlinear, diffusion equations for ionic species, which include the contribution of migration, local electroneutrality, and homogeneous reactions. The anodic and cathodic regions are not predefined but, instead, are determined by values of local concentration and potential from the simulation results. The growth of nm-scale films was calculated implicitly without using finite-element meshing and surface coverage was expressed in terms of the thickness in units of monolayers. The model also accounted for the effect of porous CuCl film thickness on the surface oxygen concentration and potential applied on electrochemical reactions. The influence of temperature was included on model parameters such as equilibrium rate constant, diffusion coefficient, Henry’s law constant, solubility product constant and kinetic parameters associated with electrochemical reactions. Transient droplet temperature was described by interpolating results from a one-million-year simulation for the temperature change on the used fuel container surface. 4 A total of 28 dependent spatial-temporal variables including species’ concentrations, potentials and local corrosion rate were solved in this model. In the current version of model, two extreme conditions were chosen such that droplet boundary has a faster or slower rate of oxygen decay for an initially air-saturated droplet. The model shows a 10-year time-dependent radial distribution of anodic and cathodic current density, surface coverage of CuCl film and Cu 2 O film, and localized corrosion rates and depths. It also shows a distribution of pH, potential, and concentrations of dissolved gaseous and ionic species through the entire droplet. Temperature and oxygen concentration is shown to have a strong contribution to the simulation results. Simulations show that the depth of corrosion is almost uniform over the elapsed time simulated and the maximum deviation from the average corrosion depth was less than 0.0004% for slower oxygen decay and less than 0.002% for faster oxygen decay in 10 years. References NWMO, “Choosing a Way Forward. The Future Management of Canada’s Used Nuclear Fuel. Final Study,” Nuclear Waste Management Organization, Toronto, Ontario, 2005. R. Evans, The Corrosion of Metals, E. Arnold & Company, London, 1926. PHREEQC Version 3, United States Geological Survey, 202, https://www.usgs.gov/software/phreeqc-version-3 Guo, “Thermal response of a Canadian conceptual deep geological repository in crystalline rock and a method to correct the influence of the near-field adiabatic boundary condition”, Engineering Geology, 218 (2017), p50-p62. Acknowledgement This work was supported by the Nuclear Waste Management Organization, Canada, under project 2000904.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».