Abstract
For applications of tristructural isotropic (TRISO) fuel particles in high temperature reactors, release of
radioactive Ag isotope (110mAg) through the SiC coating layer is a safety concern. To understand the diffusion
mechanism, Ag ion implantations near the surface and in the bulk were performed by utilizing different
ion energies and energy-degrader foils. High temperature annealing was carried out on the
as-irradiated samples to study the possible out-surface diffusion. Before and after annealing,
Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) measurements
were employed to obtain the elemental profiles of the implanted samples. The results suggest little
migration of buried Ag in the bulk, and an out-diffusion of the implanted Ag in the near-surface region of
single crystal SiC. It is also found that a SiO2 layer, which was formed during annealing, may serve as an
effective barrier to reduce or prevent Ag out diffusion through the SiC coating layer.