Microstructural change and its influence on fission gas release in high burnup UO2 fuel

K. Une, K. Nogita, S. Kashibe, M. Imamura

Research output: Contribution to journalArticle

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Abstract

The microstructural change of UO2 fuel pellets (burnup: 6-83 GWd/t), base irradiated under LWR conditions, has been studied by detailed postirradiation examinations. The lattice parameter near the fuel rim in the irradiated UO2 increased with burnup and appeared to become constant beyond about 50 GWd/t. This lattice dilation was mainly due to the accumulation of radiation induced point defects. Moreover, the dislocation density in the UO2 matrix developed progressively with burnup, and eventually the tangled dislocations organized many sub-grain boundaries in the highest burnup fuel of 83 GWd/t. This sub-grain structure induced by accumulated radiation damage was compatible in appearance with SEM fractography results which revealed sub-divided grains of sub-micron size in as-fabricated grains. The influence of burnup on 85Kr release from the UO2 fuels has been examined by means of a postirradiation annealing technique. The higher fractional release of high burnup fuels was mainly due to the burnup dependence of the fractional burst release evolved on temperature ramp. The fractional burst release was represented in terms of the square root of burnup from 6 to 83 GWd/t.

Original languageEnglish
Pages (from-to)65-72
Number of pages8
JournalJournal of Nuclear Materials
Volume188
Issue numberC
DOIs
Publication statusPublished - Jun 1992

Fingerprint

fission
Gases
Dislocations (crystals)
gases
bursts
Fractography
Crystal microstructure
Radiation damage
fractography
Point defects
Lattice constants
Grain boundaries
ramps
rims
radiation damage
pellets
point defects
Annealing
lattice parameters
Radiation

All Science Journal Classification (ASJC) codes

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

Cite this

Microstructural change and its influence on fission gas release in high burnup UO2 fuel. / Une, K.; Nogita, K.; Kashibe, S.; Imamura, M.

In: Journal of Nuclear Materials, Vol. 188, No. C, 06.1992, p. 65-72.

Research output: Contribution to journalArticle

Une, K. ; Nogita, K. ; Kashibe, S. ; Imamura, M. / Microstructural change and its influence on fission gas release in high burnup UO2 fuel. In: Journal of Nuclear Materials. 1992 ; Vol. 188, No. C. pp. 65-72.
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