Published online by Cambridge University Press: 23 March 2012
Since the 1970s there has been a steady increase in research on candidate ceramic and glass-ceramics for immobilisation of HLW and ILW, both from the aspects of crystal-chemical design and processing technology. The variety of ceramics and glass-ceramics designed for different types of HLW and ILW will be presented, notably those which are problematic for vitrification. Several of these materials are optimally processed by hot isostatic pressing (HIP), a technology which can consolidate calcined intermediate-level and high-level nuclear waste. Thus we are targeting such wastes for development of alternative waste forms. The essential process steps during the HIP cycle will be outlined. Effective consolidation of a wide variety of tailored glass-ceramic and ceramic waste forms has been demonstrated. The principal advantages of the HIP technology include negligible offgas during the high temperature consolidation step, relatively small footprint, and high waste/volume loadings. While it can be argued that the “nuclear waste problem” is essentially solved technically, at least with current regulatory guidelines, different perceptions of the “best” waste form and processing method for a given waste, together with the general current lack of agreed locations for final repositories, or even interim storage sites, create uncertainties.