Melting temperature of uranium - plutonium mixed oxide fuel

not registered; Hirosawa, Takashi  

Fuel melting temperature is one of the major thermodynamical properties that is used for determining the design criteria on fuel temperature during irradiation in FBR. In general, it is necessary to evaluate the correlation of fuel melting temperature to confirm that the fuel temperature must be kept below the fuel melting temperature during irradiation at any conditions. The correlations of the melting temperature of uranium-plutonium mixed oxide (MOX) fuel, typical FBR fuel, used to be estimated and formulized based on the measured values reported in 1960's and has been applied to the design. At present, some experiments have been accumulated with improved experimental techniques. And it reveals that the recent measured melting temperatures does not agree well to the data reported in 1960's and that some of the 1960's data should be modified by taking into account of the recent measurements. In this study, the experience of melting temperature up to now are summarized and evaluated in order to make the fuel pin design more reliable. The effect of plutonium content, oxygen to metal ratio and burnup on MOX fuel melting was examined based on the recent data under the UO - PuO - PuO ideal solution model, and then formulized. The correlation obtained in this work is as-follows; T = T + T + T + T ----(A) T = 3120 T = -5.7537PU + 1.363110 PU + 1.795210 PU T = -1.41 PU (2.00 - OP)/0.39 OP : OP = /(0.01PU) T = -5.0BU/10000 where T is the melting temperature (degree of K), PU is the weight fraction of PuO in the mixed oxide fuel, OM is the oxygen to metal ratio, and BU is the burnup in the unit of MWd/MTM. respectively. T (plutonium content), T (O/M Ratio), ...