Pages: 243-248

Authors: Slavko D. Dimović, Dušan P. Nikezić, Marija Z. Šljivić-Ivanović, Ivana V. Jelić, Vojislav Đ. Stanić, Mirjana B. Radenković, and Boris B. Lončar

Abstract

The possibility of retaining Cs⁺ and Co²⁺ bound by immobilization processes in the cement matrix is defined as the subject of its investigation: the cement matrix formulation, the water/cement ratio, the amount of waste, and the porosity of such a structure. Implementing the standard leaching method by Hespe the possibility of comparing different authors' results was achieved. Diffusion and semi-empirical model were used to investigate the transport phenomenon in order to predict the leaching level for a long period of time. Leaching of Co²⁺ and Cs⁺ ions under dynamic conditions immobilized in the cement matrix dynamic conditions decreases with the increase of the sludge content, regarding porosity increase. The effects of the diffusion and surface washing are equalized, and the contribution of the matrix dissolution to the Cs⁺ and Co²⁺ transport in the cement porous media increases, on average, for one order of magnitude. The semi-empirical model gives a better approximation for Co²⁺ and Cs⁺ leaching process for the duration of the experiment while both models significantly approximate leaching results in dynamic conditions.

Key words: radioactive waste, cement matrix, leaching, mathematical modeling

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