The initial oxidation behavior of uranium and uranium-titanium alloys in standing storage

Environmental Stability of Actinide Oxides Mapped by Integrated and Accurate First-Principles Calculations

“…On the experimental U metal samples contacting humid atmospheres and water solutions, the hydration phenomenon ubiquitously takes place and considerably promotes the environmental degradation process of the native oxide films, especially at the reactive grainboundary sites. 3,5,8,10,11,14 Such a hydration process occurring at defect sites and its corrosion promoting effect can be understood more clearly by illustrating a similar example with the prototypical α-Al 2 O 3 . The compact corundum crystal structure of α-Al 2 O 3 films can provide superior protection to many metal and coating substrates in regular environments.…”

“…It is the spontaneously formed oxide films that serve as the native corrosion barriers for the metal substrates because of the reduced surface adsorption and blocked defect permeation. 6,7 Thus, in various chemical and mechanical treatment methods (e.g., alloying and ultrasonic surface rolling) that can obviously improve the corrosion resistance of actinide metals, 3,8 the key mechanisms are always associated with the optimized microscopic states of the native oxide films. The environmental water molecules may aggravate the breakdown of oxide films through accelerating the surface electrochemical reactions on these native outer-layer oxide films and then forming loose and pyrophoric hydrides at the oxide/metal interfaces.…”

“…These adverse processes can cause the catastrophic structural and chemical degradation phenomena (e.g., cracking of the passivating oxide films and fuel particles, promoted hydration of oxides, and stimulated pyrophoric hydrogenation of metal substrates) and finally will severely challenge the safe service and storage of related actinide metals and nuclear fuels. [1][2][3]5,6,8 The thermodynamic stability of oxides in atmospheric conditions can be described by their free energies of formation (Δ f G), and the electrochemical passivation and corrosion trends can be depicted by Pourbaix diagrams, 20−26 which require the Δ f G values as input data to derive the relative electrochemical stabilities between the involved oxides, aqueous ions, and metals at different solution pH values and electrode potentials. The conventional Pourbaix diagrams for metal oxides are usually simulated using their Δ f G values archived in the experimental databases, 20,26 where the measured combustion or oxidation heat at a high temperature for an oxide is usually combined together with its relative freeenergy variation at lower temperatures to derive the absolute Δ f G values.…”

Uranyl Photocatalyzed Polystyrene Oxidative Degradation under Visible Light in a Green Solvent

“…In other words, external exposure to uranium is not dangerous unless there is direct ingestion or inhalation of high concentrations of uranium . The reserves of uranium in nature (5 × 10 6 t) are greater than those of some precious metals such as platinum-group metals (i.e., Ir, Os, Pd, Pt, Ru and Rh, 7 × 10 4 t in total). , Although depleted uranium (byproduct of uranium enrichment, ∼99.8% 238 U) has a number of civilian applications, e.g., in ballasts in aircraft, radiation shields in medical equipment, glassware and ceramics, alloy doping, etc., there still remains enormous potential for uranium applications in other fields. When suitable precautions are taken, the civilian use of depleted uranium does not pose obvious health risks.…”

A Machine Learning Method for Predicting Corrosion Weight Gain of Uranium and Uranium Alloys

“…Accelerated corrosion tests have traditionally been conducted to simulate corrosion behavior in a variety of environments, with various electrochemical techniques widely used to predict the corrosion behavior of metals [ 6 ]. Li et al [ 7 ] established a prediction model of uranium oxidation and verified it via a 4-year experiment with kinetics parameters obtained through simulated storage and accelerated experiments. Tom et al [ 8 ] presented a description of the implementation of corrosion products into a predictive corrosion model that can be used for the numerical simulation or empirical prediction of uniform corrosion progression.…”