Chemical durability of high level nuclear waste forms

Amorphous and crystalline solids considered as potential host matrices for specific immobilization of long-lived radionuclides are reviewed. Based on the available literature, their long term behaviour is described in terms o f dissolution rate and radiation effects. Presently, the most interesting w aste forms have been clearly identified for each family: glasses, glass cer amics, phosphates, titanates, silicates and oxides. Strong research efforts have to be pursued not for proposing new matrices but in order to complete the data base on chemical durability, irradiation behaviour and mechanical properties of selected solids. Moreover, studies have to be performed to e valuate the relationships between radiation effects, mechanical constraints and alteration mechanisms.