On the rate theory model for fission-gas behaviour in nuclear fuels

The rate theory model of the homogeneous nucleation and subsequent growth of intragranular fission gas bubbles has been extended to allow for the inclusion of very much larger bubbles. A simple treatment of the behaviour of grain-boundary gas is included in the present model, which allows for the re-solution of gas from intergranular bubbles. The effect of varying the model parameters and of including bubble mobility in the theory have been considered and it is concluded that the dominant parameters for gas release are temperature, grain size, re-solution rate and bubble migration and coalescence.