Durability evaluation of glasses to immobilize Fukushima (1F) secondary waste using ASTM C1220 (MCC-1) testing

Following the 2011 accident at the Fukushima Daiichi Nuclear Power Plant (1F), contaminated water was treated to remove radionuclides. The water treatment processes generated ∼4500 m³ of secondary wastes including sludges and spent media. Vitrification using GeoMelt® In-Container Vitrification (ICV)™ is a technology being considered for treatment of these wastes. ICV is well suited due to its ability to process a broad range of wastes at high temperatures without the need to pour glass which results in high waste loading and high chemical durability. The objective of this study was to formulate glasses suitable for ICV processing of 1F secondary wastes with high chemical durability. Thirty-six glasses were formulated for different 1F secondary waste blends with loadings ranging from 60 to 92 wt%. Materials Characterization Center durability test number 1 (MCC-1 – ASTM C1220) responses were measured for the glasses in deionized water at 90 °C for 7 to 365 days. Their MCC-1 responses were equal or below those for well-characterized reference waste glasses from US, Japan, and France demonstrating their high durability. The 1F glass MCC-1 data were combined with literature data from US, French, and Japanese high-level waste glasses and a model was fitted to MCC-1 durability response as a function of glass composition. Component effects on MCC-1 responses were discussed in context of glass alteration theory.