On the theory of fission gas bubble evolution in irradiated UO2 fuel

The standard approaches for modelling of the intra- and intergranular bubbles evolution in the UO2 fuel are critically analysed on the basis of available experimental data. It is demonstrated that the main disadvantage of the simplified treatment of the problem by the standard models can be associated with underestimation of the radiation effects at low temperatures (below 1500 degrees C) and thermal effects at high temperatures (above 1500 degrees C). The presented analysis allows a quantitative description of the bubble nucleation mechanism, adequate modelling of the bubble diffusion growth, and evaluation of the intragranular bubble number density and stable size attained under steady irradiation conditions. (C) 2000 Elsevier Science B.V. All rights reserved.