Modeling the swelling performance of UMo alloys for Al-matrix dispersion fuel

Fuel swelling by fission products is now considered the greatest factor that influences fuel performance. To gain a better understanding of the swelling behavior on UMo/Al fuel, we have investigated gas generation and have characterized fission-product swelling. The matrix-material creep and the interaction between the UMo fuel particles and the Al matrix have also been studied in the modeling of this process. The modeled phenomena also allow the prediction of UMo/Al fuel swelling. The results show that the motion of fission gaseous atoms, bubble growth and evolution and the creep of matrix materials are the basic behaviors of UMo/Al-dispersion fuel swelling. The swelling rate of the fuel exhibits a distinct knee. Before the grain subdivision, the degrees of fuel swelling at different fission rates are not evidently different. After the grain subdivision, the fuel swelling at lower fission rates is faster than that at higher fission rates. The matrix material experiences accelerated creep at high temperatures. If the fuel volume fraction is higher than 52%, the fuel swelling sharply increases after grain subdivision. The results are compared with the data from the literature, and these show reasonable agreement. The analysis provides a plausible interpretation of the behavior of UMo/Al-dispersion fuel swelling.

► The swelling performance of UMo-Al dispersion fuel is modeled by the FPIS model.
► The swelling is a direct result of the accumulation of fission-product elements.
► The matrix-material creep will be accelerated at high temperature.
► If fuel volume fraction is higher than 52% the fuel swelling will sharply increase.