Immobilization of Cesium and Strontium-based waste by metakaolin geopolymer: Effect of waste loading and water-binder ratio on the properties of the host matrix

Research outputpeer-review


The first-generation nuclear power plants and reprocessing facilities are approaching the end of their service lives [1]. As a result, spent nuclear fuel (SNF) and radioactive waste, generated by both the normal operations and decommissioning of nuclear power plants will undoubtedly rise significantly [2]. Reprocessing of SNF has long been regarded as a viable solution to address existing disposal issues. Under the Belgian waste management framework; the ASOF (Advanced Separation for Optimal management of spent Fuel) Project is advancing the development of new, innovative processes for the separation of minor actinides (Americium) and fission products Cesium (Cs) and Strontium (Sr) to optimise SNF disposal. In parallel, approaches for conditioning Cs and Sr are being investigated. Alkali-activated materials (AAMs) have been intensively studied in recent years and are considered as one of the potential alternatives to ordinary Portland cement (OPC) for waste immobilization. Geopolymer, a class of AAMs with a low calcium system and consisting of alkali aluminosilicate gel as the main product; offers a good immobilization and binding capacity of cations due to the pseudo-zeolitic structure of its amorphous network as well as high alkalinity. However, only one study exists to date in the literature concerning the possibility of co-immobilization of Cs and Sr into one single matrix. Li et al (2016 & 2018) investigated the immobilization of Cs and Sr by paper sludge (PS) ash-based geopolymer bearing 1% wt Sr(NO3)2 and CsNO3 to address the issue of Cs and Sr present in contaminated water from Fukushima Daiichi NPP [3,4]. However, the reported mechanical properties were very low (Flexural strength < 1MPa) which potentially limits its wide adoption and application in other countries. This work aims to develop a metakaolin (MK)-based geopolymer mortar bearing high Cs and Sr loading and exhibiting high mechanical properties. The focus was to evaluate the effect of the water-binder (W/B) ratio and simulated Cs and/or Sr waste loading on the properties of MK geopolymer.
Original languageEnglish
Title of host publicationProceedings of the DuRSAAM 2023 Symposium on Advancing Alkali-Activated Materials
EditorsStijn Matthys, Alessandro Proia
PublisherUGent - Universiteit Gent
Number of pages4
ISBN (Electronic)9789082526844
StatePublished - 8 Feb 2023

Cite this