PNNL

Abstract

Cements used in global nuclear waste treatment, storage, and disposal require thorough testing of fresh and cured properties to demonstrate regulatory requirements are met. Yet, testing cements using actual radioactive wastes or simulants is often prohibitive during scoping efforts, necessitating the use of radionuclide surrogates. Cerium (Ce) is often used as a surrogate for actinides, like uranium (U) and plutonium (Pu) in spent nuclear fuel. However, few studies have explored how Ce impacts the rheological and physical properties used to qualify a cement for use. This work compares the fresh and cured properties of three classes of cements with and without ceria (CeO2), including ordinary portland cements, ultra-high performance cement composites, and magnesium phosphate cements. Due to CeO2 sorption of water (54 vol%) that effectively decreases the water available to hydrate and for binding cement phases, variations in common cement properties were detected. These observed trends suggest that surrogate CeO2 –cementitious matrices may not be representative of matrix behaviours when using actual U and Pu sources.