Applicability of alkaliactivated cement for immobilization of lowlevel radioactive waste in ion-exchange resins

Abstract

All generated and collected low-level radioactive wastes (LRW) should be processed into final products for a long-term disposal without loss of their properties. Worldwide, cementation is the most widely used technology for immobilization of nuclear wastes. Due to many existing varieties of LRW some of these wastes are incompatible with the process of hydration and hardening of a cement matrix and require optimization of cement immobilization technologies. The paper presents the results of devising new formulations of multi-component alkali-activated cement, which is aimed at complex processing of low-level radioactive waste with ion-exchange resins. The radioactive wastes to be immobilized included two types of ion-exchange resins: Cation- and anion-exchange resins mixed as 2:1 with pH=12 and anion-exchange resin with pH=5. Analysis of the obtained results from the developed optimal recipes proved that the properties of the final products are in compliance and in some cases even exceed those set in standards GB 7023 and GB 14569 of the P. R. China. High efficiency of the alkali-activated cement matrices for immobilization of radioactive wastes is attributed to their ability to bind radionuclides not only mechanically and adsorptionally, as it happens in case of traditional cement matrices, but also chemically - within the composition of zeolite-like hydration products of the R2O·MeO·Al2O3·nSiO2mH2O or R2O·Al2O3·nSiO2mH2O types, where: R=Na, K, and Cs; Me=Ca, Mg, and Sr.