  Transmission electron microscopy (TEM) experiments were carried out on aged
under tritium palladium powder samples. The experiments were devoted to the
study of the evolution of 3He bubbles (size, density) appearing during aging.
The study, using a new sample preparation, was focused for the first time on
long aging time, up to 8 years. The TEM results indicated the presence of
nanometer size bubbles (2 - 3 nm in diameter) with densities close to 5x10^23
m-3.
