MODELING OF ION-BOMBARDMENT EFFECTS ON NUCLEAR WASTE GLASS LEACHING.

An analytic model to account for the effects of ion bombardment on the dissolution rate of nuclear waste glasses has been developed. The model postulates that impinging ions register latent tracks in the glass matrix and relies on geometric and statistical considerations to reproduce the trends observed experimentally. As a first approximation, the tracks are represented by cylindrical regions of enhanced chemical reactivity. Dissolution of the glassy material contained in a track proceeds at a velocity given by Kv//g, where v//g represents the dissolution rate of undisturbed glass and K denotes the enhancement factor. In order to get reasonable agreement with recently published experimental information, it is necessary to postulate that K is a function of the ion dose. Assumptions used in the model are presented, and the effects of varying a select set of parameters are discussed.