Durability of hot uniaxially pressed Synroc derivative wasteform for EURO-GANEX wastes

Abstract

A new titanate wasteform, Synroc-Z, was developed to contain minimal host phases for actinides and thus better suit the EURO-GANEX process. The processing conditions, waste loading and surface roughness were varied, and their effects on wasteform durability and microstructure were examined. Hot uniaxial pressing temperature was the most important factor in controlling density (<0.5 vol% porosity) and phase composition. Synroc-Z was found to have similar aqueous durability to Synroc-C. Leached samples formed Ti-oxide films and crystals on their surfaces as found by other researchers.At low waste loadings (<20 wt%), Synroc-Z showed slightly poorer durability performance than Synroc-C owing to its greater perovskite content (30 vs. 20 wt% respectively). However, at 35 wt% waste loading, Synroc-Z maintained its durability performance. This result is explained by the higher volume fraction of buffer phase, rutile, which allows greater flexibility for waste loading.