An analysis of the a-, ß- and γ-phases of U, using a hard-sphere model which was based upon a simple bond description, yielded fractional packing densities which agreed with the primary solute solubilities of C, N and O in a- and ß-U. This approach was inconsistent with the concept of a so-called open structure for a-U, and with the Wigner-Seitz concept of the electron theory of metals. Fast diffusion in γ-U and other host phases could be explained in terms of a modification of Hägg's rule. This was not possible for fast diffusion data on Fe and Co in the anisotropic host phases, a-U and ß-U. It was suggested that this was due to complex formation.

Fractional Packing Densities and Fast Diffusion in Uranium and other Light Actinides. H.Blank: Journal of Alloys and Compounds, 1998, 268[1-2], 180-7