Recycling Fe-rich slags in alkali activated cements and concretes for nuclear safety applications

Abstract

Non-ferrous slags are underutilized by-products from non-ferrous metal production. Owing to their richness in Fe and Si, non-ferrous slags are interesting materials for incorporation in concretes and cementitious binders for shielding applications in nuclear safety structures and during nuclear waste immobilization. The shielding properties of alkali-activated materials (AAMs) are compared with other materials (e.g. steel-magnetite concrete, barite concretes) that are considered for this application. The linear attenuation coefficient (μ) of non-ferrous slag based AAMs was determined via a dedicated setup complemented with Monte Carlo (MC) simulation using EGSnrc (Electron Gamma Shower MC toolkit). In addition, for the study of the use of AAMs as nuclear waste immobilization matrix , the impact of non-radiological isotopes of 137 Cs, 152+154 Eu and 90 Sr on the AAM matrix is evaluated. For this purpose, AAMs were synthesized based on model components simulating the properties of non-ferrous slags. The kinetics of AAM formation was studied via isothermal calorimetry. It was found that the introduction of Sr 2+ and Eu 3+ resulted in a delayed activation process.