Corrosion Properties of Oxidized Metallic Uranium and Uranium Carbide
Notice bibliographique
Résumé
The long-term strategy for nuclear waste disposal involves the isolation and containment of spent fuel in a deep geological repository (DGR). CANDU fuel pellets are made from uranium dioxide, which exhibits exceptional wasteform properties due to its remarkably low solubility under the neutral or slightly alkaline conditions expected in a DGR. However, in the early years of nuclear fuel development, some non-oxide fuel forms, such as metallic uranium or uranium carbide, were used to fuel research reactors in Canada. These legacy materials pose challenges for disposal in their current state due to their elevated reactivity, instability, and exothermic reaction with water, air, and hydrogen. These drawbacks can be alleviated, and the used fuel rendered suitable for safe disposal, by conditioning it to an oxide form before disposal. While extensive research has been performed to determine the corrosion behaviour of uranium dioxide materials, including SIMFUELs (UO 2 containing non-radioactive forms of fission products) and undoped unirradiated specimens in the presence of H 2 O 2 (a primary radiolytic oxidant) and the scavenging effect of dissolved H 2 under container failure scenarios, this study investigates the composition of the oxide forms prepared from uranium carbide and the impact of H 2 on their corrosion in the presence of H 2 O 2 . The composition and properties of oxide forms prepared from uranium carbide using different conditioning methods were studied using a suite of surface analytical techniques. Also, the influence of H 2 on their corrosion was studied via electrochemical techniques in aqueous chloride solutions containing bicarbonate anions. The morphological characteristics of the specimens were noticeably distinct, with some structural variations attributed to their conditioning methods. The preliminary electrochemical studies showed that under Ar-sparged conditions, the corrosion potential was about -100 mV; a higher potential was observed upon H 2 O 2 addition at a low concentration of 10 -6 M, indicating further surface oxidation. In Ar/H 2 (95%/5%)-sparged solution, the corrosion potential of the fuel specimen was around -450 mV before H 2 O 2 addition. Post oxidant addition, the potential increased, which suggests that the oxidation of the fuel specimen was not suppressed by the presence of H 2 at low H 2 O 2 concentration, unlike what has been seen on CANDU fuel under the same conditions. Studies using other concentrations of H 2 O 2 ranging from (0.1 µM to 50 µM) in the presence of H 2 are ongoing to understand the influence of H 2 on the fuel specimens.
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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 ».