Published online by Cambridge University Press: 10 February 2011
Synroc is a candidate waste form for the immobilisation of high level radioactive waste (HLW)[1]. It is polyphase titanate ceramic principally comprised of zirconolite, hollandite perovskite and rutile (nominally CaZrTi2O7, (BaxCsy)[(Ti3+, Al)2x+y(Ti4+)8−2x−y]O16), CaTiO3 and TiO2 respectively). Waste species substitute into the three former phases. In particular, actinides (ACTs) substitute onto the Ca and Zr sites in zirconolite and the Ca site in perovskite. Consequently over time, these phases will suffer alpha-recoil and alpha particle damage while hollandite and rutile will suffer alpha particle damage. The effect of radiation damage on the structure and consequently on the durability of Synroc's constituent phases is important to predictive modelling of Synroc's behaviour in the repository environment and risk assessment.