论文信息 - Microstructures of corrosion films on UO2 fuel oxidized in air-steam mixtures at 225°C

Microstructures of corrosion films on UO2 fuel oxidized in air-steam mixtures at 225°C

Oxidation of unirradiated UO2 fuel specimens in aerated steam above about 70% saturation (relative humidity) at 225°C yields uniformly textured or granular corrosion-product layers consisting of U3O8 and dehydrated schoepite (DS; UO3·xH2O, x ≅ 0.8). These fine-grained products (0.5 to 2.0 μm) contrast with the much larger DS crystals that are formed in aerated liquid water around 200°C. At lower steam partial pressures (30 to 70% saturation), only scattered crystals of these oxidation products are formed, also with dimensions <2 μm. Both the uniform films and the sparser microcrystalline products are thought to form by dissolution and precipitation of uranium within a thin film (a few molecules thick) of adsorbed moisture.

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