TY - JOUR
T1 - Molecular dynamics simulation of helium and oxygen diffusion in UO2+-x
AU - Govers, Kevin
AU - Lemehov, Sergei
AU - Hou, Marc
AU - Verwerft, Marc
N1 - Score = 10
PY - 2009/12
Y1 - 2009/12
N2 - 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.
AB - 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.
KW - MD
KW - molecular dynamics
KW - UO2
KW - He
KW - uranium dioxide
KW - nuclear fuel
KW - helium
UR - http://ecm.sckcen.be/OTCS/llisapi.dll/open/ezp_101346
UR - http://knowledgecentre.sckcen.be/so2/bibref/6246
U2 - 10.1016/j.jnucmat.2009.10.043
DO - 10.1016/j.jnucmat.2009.10.043
M3 - Article
SN - 0022-3115
VL - 395
SP - 131
EP - 139
JO - Journal of Nuclear Materials
JF - Journal of Nuclear Materials
IS - 1-3
ER -