Next-Generation Low-Carbon Cement Wasteforms for Safe Disposal of Radioactive Waste

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In the UK, over 150,000m3 of radioactive waste (enough to fill 60 Olympic size swimming pools) has been produced to date. Most of this radioactive waste needs conditioning by encapsulating it in cement to prevent release to the biosphere.Encapsulants based on Portland cement (PC) blended with supplementary cementitious materials (SCM) such as fly ash (FA) and blast furnace slag (BFS) are essential to cementation of much of the radioactive waste produced in the UK to date. However, with traditional SCM such as fly ash and blast furnace slag becoming increasingly scarce, development of PC/SCM encapsulants produced using abundant and readily available SCM such as limestone, calcined clays, and legacy slags, etc., is critical to ensure security of supply.There is currently limited information on what parameters of raw materials are critical to reliable application, particularly when these encapsulants are formulated with abundant SCM alternatives such as limestone, calcined clays, and legacy slags, under conditions required on nuclear encapsulation plants.This proposal investigates the mechanisms of fluid-particle and particle-particle interactions in PC/SCM encapsulants produced using limestone, calcined clays, and legacy slags as more abundant replacements for BFS and PFA,and the effect of this replacement on composition-structure-property relationships, and reaction mechanisms and kinetics.Through investigating fundamental particle interactions more robust specifications can be developed for precursor powders utilising abundant SCMs, ensuring security of supply.