The planar track model and the prediction of alpha-recoil aging in radwaste materials

High fluences of low energy heavy ions generate very thin layers of radiation-damaged material on the surface of solid-state track detectors such as glasses and silicate minerals. For glasses, such layers undergo above a critical dose complex modifications in their chemical reactivity which strongly depend on the particular glass-leachant system. We have explained this striking threshold effect by the formation of a particular structural state on both crystalline and amorphous insulators, generated by the accumulation of individual damaged islands produced by the incident ions. We first recall our experimental technique that is based on an implantation of lead ions. Then we report on new experimental results on the ion-induced etchability of two very different insulating materials, muscovite mica and soda-lime glass which are conveniently described by a refined version of our planar track model. Finally, by assimilating such lead ions to recoil nuclei emitted during the α-decay of actinide elements incorporated in radioactive waste storage materials (radwaste materials) we tentatively apply this new concept of planar track to the important problem of radiation stability of radwaste materials exposed to the internal irradiation with α-recoils and subjected to corrosion by ground waters. (author)