A microscopic model accounting for radiation effects in graphite exists, in which primary, secondary and tertiary displacements are produced with characteristic threshold energies. Annealing may occur by means of a combined nucleation and diffusion process, which at graphitization temperatures results in the complete recovery from the effects. Correlation with the observed changes in physical properties is satisfactory.

Changes with time in the spatial distribution of disturbed regions in a graphite moderator exhibiting radiation damage tend toward a steady state condition. The achievement of such a state for geometries of practical importance is discussed by example in the light of data on change of physical properties with flux, temperature, and time.