Influence of radiation on the structural dynamic characteristics of uranium dioxide

This work examines the influence of irradiation factors on the specific energy of intergrain boundaries, the edge angle of intergrain gas bubbles and the fission track diameter in uranium dioxide irradiated under reactor conditions. Irradiation of uranium dioxide under reactor conditions generally leads to the formation and development of a system of intergrain gas bubbles (IGS), which have a distinctive lenticular shape and play a particular part in the kinetics of gas swelling of fuel. The edge angle of an IGB θ is determined on the basis of the equilibrium conditions: cos θ γ*rp/2γ, where γ*rp is the specific energy of surface tension on the plane double intergrain boundary, and γ is the same on the free surface of the IGB. The literature lacks experimental data for γ*rp; the values encountered for the energy γ lie in the range from 0.628 J/m2 to around 1 J/m2. A value of 1 J/m2 is most often used in modelling calculations. This lack of precision prevents a sufficiently accurate determination of the EGB edge angle on condition of equilibrium. (author)