Effects of microstructural constraints on the transport of fission products in uranium dioxide at low burnups

Harn Chyi Lim, Karin Rudman, Kapil Krishnan, Robert McDonald, Patricia Dickerson, Bowen Gong, Pedro Peralta

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Diffusion of fission gases in UO2 is studied at low burnups, before bubble growth and coalescence along grain boundaries (GBs) become dominant, using a 3-D finite element model that incorporates actual UO2 microstructures. Grain boundary diffusivities are assigned based on crystallography with lattice and GB diffusion coupled with temperature to account for temperature gradients. Heterogeneity of GB properties and connectivity can induce regions where concentration is locally higher than without GB diffusion. These regions are produced by "bottlenecks" in the GB network because of lack of connectivity among high diffusivity GBs due to crystallographic constraints, and they can lead to localized swelling. Effective diffusivities were calculated assuming a uniform distribution of high diffusivity among GBs. Results indicate an increase over the bulk diffusivity with a clear grain size effect and that connectivity and properties of different GBs become important factors on the variability of fission product concentration at the microscale.

Original languageEnglish (US)
Pages (from-to)24-36
Number of pages13
JournalJournal of Nuclear Materials
Volume477
DOIs
StatePublished - Aug 15 2016

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Materials Science(all)
  • Nuclear Energy and Engineering

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