Specific outcomes of the research on the radiation stability of the French nuclear glass towards alpha decay accumulation

Helium implantation studies suggest that helium trapping could exist in nanometer size bubbles. SEM and TEM analysis performed on a Cm doped glass damaged by an alpha decay dose of around 1019 α g−1, showed a homogeneous glass without crystallization, phase separation or bubbles with a spatial resolution limit of 10 nm. Bubbles of significant size seem very unlikely to form at room temperatures. But, the ability to form helium bubbles of nanometer size, at temperature below the glass vitreous transition temperature cannot be excluded. However, all these studies agree on one point, the absence of macroscopic consequence on the glass integrity of accumulation of high helium concentration in the glass.