Displacement cascade initiated with the realistic energy of the recoil nucleus in UO2 matrix by molecular dynamics simulation

Classical molecular dynamics simulations have been performed to study the primary damage due to α-decay self-radiation in UO2 matrix. For the first time a displacement cascade initiated with an energy of 80 keV has been performed. Compared with the cascades initiated with lower energies of the primary knock-on atom (PKA), the morphology of the cascade shows the same features; no amorphisation and creation of point defects are observed. The discrepancy with the linear theory NRT (Norton–Robinson–Torrens) law on the creation of the number of point defects is discussed. However, differences have been found; local and temporary amorphisation appears during the thermal spike over large length scale only in the high energy cascade. Proportionally in the high energy cascade, more linear collision sequences are undergone by the uranium atoms and the oxygen atoms recombine over a larger length scale.