Ceramic Waste Forms

Abstract

Ceramic waste forms are based on crystalline or mineral phases that have survived in nature at elevated temperatures in the presence of water for 100s of millions of years. In the ceramic waste form design, waste nuclides are locked into the crystal structure which results in highly durable materials. For more than 40 years, ceramics have been commonly seen to be competitors to the baseline borosilicate glass option for the immobilization of high- and intermediate-level nuclear waste. However, it is now increasingly clear that the wide variety of extant nuclear wastes will ensure that glasses, ceramics and indeed glass-ceramics will have very significant roles to play in the immobilization of nuclear wastes and thus confirm one of the criteria of sustainability for nuclear power production. Ceramic waste forms can be produced by cold pressing and sintering, hot pressing, hot isostatic pressing (HIP), melting and spark plasma sintering (SPS). Currently, HIP technology is making a strong impression as a very advantageous processing technique for the consolidation of ceramics and glass–ceramics for nuclear waste immobilization. ANSTO is currently building a Synroc Waste Treatment Facility, a first of a kind plant which deploys the HIP technology at the industrial scale for the treatment of its intermediate-level liquid waste from radiopharmaceutical production.