First Principles Modelling of Oxygen Impurities in UN Nuclear Fuels

Journal Article · Tue Jul 15 00:00:00 EDT 2008 · Journal of Nuclear Materials, 377(3):492-495

DOI:https://doi.org/10.1016/j.jnucmat.2008.04.015· OSTI ID:1010485

Kotomin, Eugene Alexej; Mastrikov, Yuri A

We report results of first principles VASP supercell calculations of O impurity in UN fuels placed either at an interstitial tetrahedral position or as a substitution for a host N ion. In the latter case O perfectly fits into N site producing no lattice distortion. Such the O substitutional impurity only slightly affects the formation energies of U and N vacancies nearby. In both interstitial and substitutional positions O atom attracts the additional electron density and transforms into the negatively charged ion. Oxygen incorporation into pre-existing N vacancy is energetically more favourable than into the interstitial position. The O impurities produce an additional peak at the low energy side of N contribution to the DOS calculated for uranium mononitride which could be used for the O identification by means of the UPS spectroscopy. We compare also the DOS calculated for UN and hypothetical isostructural UO. Both O solution and incorporation energies are negative, indicating that O penetration into UN fuel is the energetically favourable. The migration energy of the interstitial O ion is estimated as 2.8 eV.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1010485
• Journal Information: Journal of Nuclear Materials, 377(3):492-495, Journal Name: Journal of Nuclear Materials, 377(3):492-495
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory