Silver Diffusion in Coated Fuel Particles

Abstract

An innovative method has been developed to trap silver (Ag) between two layers of silicon carbide (SiC) produced by chemical vapor deposition at 1300°C. The study has shown for the first time that silver diffuses through intact SiC in tristructural isotropic‐coated particles. We also refute some speculations reported in previous studies by showing that silver can diffuse in stoichiometric SiC and that it is the differences in SiC microstructure that play a fundamental role in the diffusion process rather than the formation of nanocracks due to a mechanical process. Our results stress the importance of the microstructure inherent to the SiC produced by fluidized bed chemical vapor deposition on Ag diffusion.

The role of Pd in the transport of Ag in SiC

“…This is seemingly in contradiction with the findings of López-Honorato et al [15]. The findings by López-Honorato et al still need to be independently verified.…”

“…Recently in research published by Lopez-Honorato et al [15] results were presented in support of a theory of grain boundary migration of Ag in SiC. The authors developed a technique to successfully trap Ag between two layers of CVD grown polycrystalline SiC on TRISO particles.…”

Iodine assisted retainment of implanted silver in 6H-SiC at high temperatures

“…Silver diffusion in CVD-SiC is now well understood. It is mainly due to grain boundary diffusion [10,[16][17]. However the influence of grain boundary structure on diffusion is still unclear [16][17].…”

Kinetic Monte Carlo (KMC) simulation of fission product silver transport through TRISO fuel particle

“…However, they do not specifically provide insight into the silver release mechanism. A variety of mechanisms have been proposed [2,[16][17][18][19][20][21] including a vapor phase transport mechanism through nanocracks [22], trapping mediated solid state diffusion [23], and/or grain boundary diffusion [24]; but no single mechanism can provide a fully self-consistent explanation of the experimental data, and thus, the exact transport mechanism(s) remain unknown.…”