The diffusivity of 134Cs and 51Cr in the stainless steel was studied at 680 to 870C by using standard sectioning techniques. It was found that the penetration distances were very limited, and decreased with decreasing O potential. The diffusion of Cr along grain boundaries was enhanced in samples which had been pre-loaded with Cs. The grain boundary diffusion data for Cr could be described by:

D (cm2/s) = 1.3 x 10-4 exp[-62.4(kcal/mol)/RT]

The corresponding expression for material which was pre-diffused with Cs was:

D (cm2/s) = 2.1 x 10-7 exp[-48.0(kcal/mol)/RT]

It was concluded that Cs was not a fast diffusant, that its penetration was very limited at low O potentials.

H.Matzke, S.Pickering: Journal of Nuclear Science and Technology, 1983, 20[3], 237-45