A simplistic analytical treatment is given of the effects of dislocations and solid fission products on the behavior of fission gas in oxide fuel elements during fast thermal transients. The analysis is coupled with the BUBE code (a code that models equilibrium and nonequilibrium fission gas bubbles in thermal transients) and used to analyze two Transient Reactor Test Facility transients. The results suggest that the effect of dislocations on swelling and fission gas release is negligible, but that the effect of solid fission products is important.