The Effect of Composition on Short- and Long-term Durability of UK HLW Glass

Publication date: 2014 Source:Procedia Materials Science, Volume 7 Author(s): Mike T. Harrison An understanding of the aqueous durability of glass is essential for determining the dissolution and release of radionuclides from vitrified nuclear waste in a geological disposal facility over short and long timescales. There are many factors that determine the rate of glass dissolution in aqueous solution, and environmental factors such as temperature and pH will be significant. However, in terms of glass properties, the composition has the biggest influence on aqueous durability. The majority of High Level Waste (HLW) worldwide has been immobilised using borosilicate glass, although within this family there are significant compositional variations between different countries depending on the composition of the waste being vitrified. For example, the French R7T7 HLW glass contains calcium, while the Magnox waste glass produced in the UK contains significant quantities of magnesium, which results in different dissolution behavior. This paper summarizes the main compositional variations in UK vitrified HLW and identifies the key similarities and differences in composition that affect short- and long-term glass durability in aqueous solution. The effect of a number of key elements is discussed along with the current state of the art understanding of how they impact on the glass dissolution mechanisms.
Source: Procedia Materials Science - Category: Materials Science Source Type: research