The impact of the collision cascades on the xenon and helium clusters in PuO2 crystals. A molecular dynamics simulation

The interaction of collision cascades initialized by alpha decays in PuO2 crystals with xenon, helium and mixed Xe-He bubbles of linear dimensions of 1-2 nm was studied by a molecular dynamics technique. The bubbles were not destroyed by the cascades studied, however individual fast Xe and He atoms could be released. These fast atoms received high energies up to 90% of the collision cascade energy (80 keV). Also, the diffusion migration of helium atoms to the region of the crystal lattice damaged by the collision cascade was detected. Xenon atoms did not diffuse to the damage area on the simulated time scale. However, the xenon clusters changed their shape in the disordered surroundings.