Molecular dynamics simulation of helium and oxygen diffusion in UO2+-x

Kevin Govers, Sergei Lemehov, Marc Hou, Marc Verwerft

    Research outputpeer-review


    Atomic scale simulation techniques based on empirical potentials have been considered in the present work to get insight on helium diffusion in uranium dioxide. By varying the stoichiometry, together with the system temperature, the performed molecular dynamics simulations indicate two diffusion regimes for He. The first one presents a low activation energy (0.5 eV) and suggests oxygen vacancies assisted migration. This regime seems to provide the major contribution to diffusion when structural defects are present (extrinsic defects, imposed, e.g. by the stoichiometry). The second regime presents a higher activation energy, around 2 eV, and dominates in the higher temperature range or at perfect stoichiometry, suggesting an intrinsic migration process. Considering the dependance of He behaviour with oxygen defects, oxygen diffusion has been considered as well in the different stoichiometry domains. Finally, further investigations were made with nudged elastic bands calculations for a better interpretation of the operating migration mechanisms, both for He and O.
    Original languageEnglish
    Pages (from-to)131-139
    JournalJournal of Nuclear Materials
    Issue number1-3
    StatePublished - Dec 2009

    Cite this