Ex-Reactor Determination of Thermal Gap Conductance between Uranium Dioxide:Zircaloy-4 Interfaces

  • J. E. Garnier
  • S. Begej
  • A. O. Desjarlais
  • R. P. Tye


An ex-reactor study was undertaken to determine the thermal gap conductance between UO2 and Zircaloy-4. Both a transient technique (Modified Pulse Design) and a steady state technique (Modified Longitudinal Design) were used. The experimental variables were the mean-plane gap (2.7–135.0 µm), gas composition (He, Ar, He:Ar mixture, He:Xe mixtures), surface roughness, and temperature (293–893 K). The pressure was held constant at one atmosphere. The results were compared with gap conductance calculations utilizing three temperature jump distance models, and it was concluded that the GAPCON-THERMAL II model fits the data best. Considerable scatter was evident and was attributed to a failure to fully account for the three-dimensional aspect of a narrow gap and to a lack of accurate knowledge of the gaseous thermal accommodation coefficients of He, Ar, and Xe on UO2 and Zr-4 surfaces.


Uranium Dioxide Contact Conductance Accommodation Coefficient Thermal Contact Conductance Pacific Northwest Laboratory 
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Copyright information

© Purdue Research Foundation 1983

Authors and Affiliations

  • J. E. Garnier
    • 1
  • S. Begej
    • 1
  • A. O. Desjarlais
    • 2
  • R. P. Tye
    • 2
  1. 1.Pacific Northwest LaboratoryRichlandUSA
  2. 2.Dynatech R&D Co.CambridgeUSA

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