SRE CORE III FUEL ELEMENTS THERMAL ANALYSIS

The initial 30-Mw SRE Core III loading will contain a total of 33 fuel elements. Of these, the central 7 fuel elements are test elements and the remaining 26 are driver elements; 4 of the 7 test elements are designated as standard test elements. These elements are identical to the driver elements with the exception of the active fuel length. The remaining 3 test elements are designated as special test elements and incorporate fuel rods of smaller diameter and increased enrichment to obtain higher burnup rates, greater specific power, and higher fuel temperatures. Geometry design data for the various elements considered in the analysis was obtained from Dwg. No. 650 deg F, the mixed-mean coolant outlet temperature for the core at 1200 deg F ( plus or minus 15 deg F), the maximum average temperature on the cladding at 1275 deg F, and the maximum fuel temperature in the range of 2000 to 2100 deg F. The thermal performance of the fuel elements was analyzed with the SORTD code and the Heating code. The results of the analysis are presented in tabular form. Axial temperature profiles are also presented for representative fuel elements. The core outlet coolant mixed-mean temperature was found to be 1185 deg F. For the special test, standard test, and highest powered driver elements the coolant outlet temperature is limited to values below 1200 deg F because of the specified maximum value of cladding temperature. For the remaining elements the coolant outlet temperature is 1200 deg F. Maximum fuel temperatures are at values less than 2000 deg F with the exception of the special test elements. These have maximum fuel temperatures in the range of 2000 to 2100 deg F. Recently, the highest powered driver element'' was redesignated as standard test element'' because of the high power level associated with this fuel element position. (auth