COATED NUCLEAR-FUEL PARTICLES - COATING PROCESS AND ITS MODEL

A model of the decomposition process postulated the formation and growth of nuclei into agglomerates that are captured by the fuel particles. The evolution of the model involved many simplifications, and to reduce the number of variables involved, standardized operating conditions are assumed. The most important of these for comparative studies is the concept of operating at a constant reaction zone temperature. When this is done, many of the anomalies previously ascribed to the effect of different source gases are removed. An experimental program has been carried out to test the model, and excellent correlations are found between the predicted and actual size of agglomerates that can be observed in the coating structure. The agglomerate size is also correlated with coating failure.