Safe, efficient cementation of challenging radioactive wastes using alkali-activated materials - 22327

The generation of sludge wastes results from decontamination of liquid effluents and radioactive waste waters. This has historically arisen at sites such as the Enhanced Actinide Removal Plant (EARP) at Sellafield Ltd, UK and the Advanced Liquid Processing System (ALPS) at Fukushima Daichii, Japan. During these processes, ferric-sludge wastes are generated when hydrous ferric oxides (HFOs) are used to adsorb hydrolyzable ionic species from solution. Safe treatment of these wastes is therefore imperative to ensure the long-term immobilisation of the radioactive contaminants contained within them. Alkali-activated metakaolin (Al₂O₃-2SiO₂) clays (a.k.a. 'geopolymer' cements) have been proposed as a potential immobilisation matrix for these radioactive ferric-sludge wastes. Here, we describe the production and characterisation of potassium-silicate activated metakaolin geopolymers used for the immobilisation of a simulant ferric-sludge waste. (authors)