The diffusion of 110mAg in as-received, oxidized and fast neutron-irradiated graphitic matrix (A3-3) and in original (A3-27) material was studied in vacuum by measuring the release kinetics from cylindrical specimens. The latter had previously been doped with carrier-free 110mAg at 1000C. Concentration profiles were measured after the release of part of the 110mAg which was initially present. It was found that the release kinetics and the concentration profiles satisfied Fick's second law. At temperatures ranging from 800 to 1300C, and for Ag concentrations of less than 4 x 10-4at%, the diffusion data could be described by:

D (cm2/s) = 6.80 x 105exp[-2.71(eV)/kT] (original A3-3 material)

D (cm2/s) = 1.61 x 104exp[-2.67(eV)/kT] (irradiated A3-3 material)

D (cm2/s) = 1.32 x 104exp[-2.55(eV)/kT] (original A3-27 material)

It was noted that the oxidation of A3-3 accelerated Ag migration. The isotope was found to be markedly enriched in the binder C which linked the graphite grains in the matrix.

The Diffusion of Silver in the Graphitic Matrices A3-3 and A3-27. Hoinkis, E.: Journal of Nuclear Materials, 1994, 209[2], 132-47