Sorption of Some Fission Products and Actinides in Concrete Systems

Abstract

AbstractThe sorption of some actinides (Th, U, Np, Pu and Am) and fission products (I, Cs) was measured on two types of Standard Portland cements as well as on samples from old (70 years) hydro power dam constructions using a batch technique. Pore water compositions were analysed, and artificial pore water solutions were used as aqueous phases in the experiments. Measurements were also performed on five other concrete types (not reported in detail in this paper) to illustrate the effects of the cement matrix composition on the sorption behaviour of the radionuclides.The sorption of actinides in the trivalent (americium), tetravalent (thorium) pentavalent (neptunium) and hexavalent (uranium) states was high in all the studied concrete systems.Generally, the sorption of cesium was low due to the low exchange capacity of the cement and the high concentration of competing cations in the pore waters.The sorption of iodine was much higher than in most silicate minerals of geologic origin.The differences between the various concrete systems were generally minor in terms of their sorbing capacities.