NUCLEAR CHEMISTRY

Subsurface corrosion of uranium

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Science  31 Jul 2015:
Vol. 349, Issue 6247, pp. 491-492
DOI: 10.1126/science.349.6247.491-f

Uranium dioxide, the most common form of nuclear fuel, becomes mobile as it oxidizes. Although oxidative corrosion is inherently a surface-mediated process, interstitial oxygen atoms can induce oxidation many atomic layers deeper. By detailing the surface structure and composition of UO2 after exposure to oxygen in air and water, Stubbs et al. show that oxidation does not follow a classical diffusion pattern. Instead, interstitial oxygens preferentially occupy every third atomic layer below the terminal (111) surface. This pattern is a product of the delocalized electronic structure of nonsurface U atoms, which also allows for the coexistence of three U oxidation states.

Phys. Rev. Lett. 114, 246103 (2015).

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