Ex-Reactor Determination of Thermal Gap Conductance between Uranium Dioxide and Zircaloy-4. Stage II: High Gas Pressure

摘要

An ex-reactor study of the thermal gap conductance between Uranium Dioxide and Zircaloy-4 was performed under varying conditions of gas pressure (0.1 to 7 MPa); temperature (to 763 K); gas composition (Helium, Argon, He:Ar & He:Xe) and separation distance (to 23 micrometer). A description of the high pressure autoclave, specimen holder and associated apparatus is given. Experimental results are plotted and tabulated. An assessment of errors is made. This report concentrates on high gas pressures. An earlier report (NUREG/CR-0330; April 1979) provided data at low gas pressure. Results show that gap conductance increases rapidly with increasing gas pressure (i.e., gas density) over the range between 0.1 and 1 MPa.