Ex-Reactor Determination of Thermal Contact Conductance between Uranium Dioxide:Zircaloy-4 Interfaces
A scoping study was performed using a modified longitudinal design apparatus to investigate the effects of contact pressure (0 to 14.68 MN/m2), surface roughness, and surface error-of-form on the contact conductance between depleted uranium dioxide and Zircaloy-4. The results are compared to four existing contact conductance models which assume that the contact conductance depends on the surface roughness and elastic/plastic deformation of surface asperities. The model by Mikic-Todreas was found to best fit the data. It was also found that the pressure exponent depends on the contact pressure, surface roughness, and surface error-of-form rather than being independent of these parameters as assumed by the models. The data is also found to qualitatively fit the model by Dundurs and Panek which thereby suggests that the surface error-of-form may be the predominant factor in predicting the contact conductance, rather than the surface roughness. It is also observed that the fluid (i.e., gas) conductance rather than the contact conductance constituted the major contribution to the total interface conductance in the contact pressure range studied.
KeywordsContact Pressure Uranium Dioxide Contact Conductance Thermal Contact Conductance Interfacial Thermal Conduc
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