Radiation effects in solids designed for the immobilisation of high level nuclear waste

Abstract

Radiation effects in different variants of crystalline ceramics, including titanate-based synroc ceramics, will be reviewed on the basis of data obtained from natural metamict minerals where appropriate, plus synthetic phases irradiated in a variety of ways to produce atomic displacements. Poly-phase wasteforms will experience different tendencies for lattice expansion in the different phases, giving rise to intergranular stresses. Single-phase polycrystalline wasteforms composed of a phase which expands anisotropically also experience intergranular stresses. These effects are grain-size dependent. Examples from the literature of intergranular stresses in irradiated solids will be presented for BeO, alumina, a particular synroc-type ceramic, and a glass-ceramic. The question of zirconates versus titanates for immobilisation of surplus plutonium will be discussed in terms of recent experiments on phase constitution and heavy ion irradiation effects. Finally, other candidate ceramics designed for surplus Pu immobilisation will also be assessed. © 2003 Trans Tech Publications Ltd