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Title: Pipe and grain boundary diffusion of He in UO2

Molecular dynamics simulations have been conducted to study the effects of dislocations and grain boundaries on He diffusion in $$\text{U}{{\text{O}}_{2}}$$ . Calculations were carried out for the {100}, {110} and {111} $$\langle 1\,1\,0\rangle $$ edge dislocations, the screw $$\langle 1\,1\,0\rangle $$ dislocation and Σ5, Σ13, Σ19 and Σ25 tilt grain boundaries. He diffusivity as a function of distance from the dislocation core and grain boundaries was investigated for the temperature range 2300–3000 K. An enhancement in diffusivity was predicted within 20 Å of the dislocations or grain boundaries. Further investigation showed that He diffusion in the edge dislocations follows anisotropic behaviour along the dislocation core, suggesting that pipe diffusion occurs. Here, an Arrhenius plot of He diffusivity against the inverse of temperature was also presented and the activation energy calculated for each structure, as a function of distance from the dislocation or grain boundary.
 [1] ;  [2] ;  [1] ;  [2] ;  [1] ;  [2]
  1. Imperial College London, London (United Kingdom)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0953-8984
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Physics. Condensed Matter
Additional Journal Information:
Journal Volume: 28; Journal Issue: 40; Journal ID: ISSN 0953-8984
IOP Publishing
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY molecular dynamics; He diffusion; dislocation; grain boundary; UO2