A Fission Gas Swelling Model Incorporating Re-Solution Effects

Current fuel swelling models based upon the growth of fission gas bubbles do not consider effects due to radiation induced re-solution phenomena. This paper describes a fission gas swelling model which assumes that fission fragments will destroy existing gas bubbles and maintain the resulting gas atoms in supersaturated solid solution. Such a model should be particularly applicable to fuels operating at low temperatures and high fission rates. Bubble nucleation and growth then take place until another fission fragment again passes through the same region. Bubble growth is calculated using reaction rate theory over the period of time in which no radiation damage occurs. The model predicts bubble growth significantly smaller than that experimentally determined in UO₂. This discrepancy is attributed to assumptions made in defining the re-solution mechanism. The model implies that fission gas bubble growth is a state junction independent of path.