Characterization and modelling of helium bubbles in self-irradiated plutonium alloys

The self-irradiation damage generated by alpha decay of Pu results in the formation of lattice defects and helium and uranium atoms. Over time, microstructural evolution as a result of the self-irradiation may influence the physical and mechanical properties of the material. Transmission electron microscopy investigations of Pu-Ga alloys ranging in age up to 42 years old, reveal the presence of nanometre-sized helium bubbles. The number density of bubbles and the average size have been determined for eight different age materials. The nucleation and growth of these bubbles have been modelled with rate equations.