Effects of UO2 fuel microstructure and density on fuel inreactor performance

Lena Hansson

Research output: Book/ReportReport


The volume changes of UO2 fuel pellets, produced by neutron irradiation, can be characterized by two processes: fission spike induced densification through pore shrinkage and later fission product induced swelling of UO2 matrix. In-pile densification is controlled by the initial density and microstructure of the fuel, particularly by the pore size distribution. The extent of swelling depends mainly on the amount of fission products produced, but the fission gas release as well as the swelling may be reduced by increasing the grain size of UO2. Fabrication of fuel pellets having certain in-reactor properties requires detailed knowledge of the effects of individual fabrication parameters. The irradiation experience of fuels fabricated by using different conversion and pelletizing methods is extensive. Based on this experience, some general characteristics of stable/well-performing fuel microstructures have been summarized.
Original languageEnglish
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Number of pages58
ISBN (Print)951-38-3030-6
Publication statusPublished - 1988
MoE publication typeNot Eligible

Publication series

SeriesValtion teknillinen tutkimuskeskus. Tiedotteita


  • nuclear fuel pellets
  • uranium oxides
  • densification
  • swelling
  • gases


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