Transport of Radioactive Solutes in the Presence of Chelating Agents

Abstract

It has been stated that chelate formation of radionuclides with chelating agents found in groundwater significantly influenced the transport behavior of the radionuclides in subsurface. The effect of chelating agents on the transport of radioactive solutes in porous media is analyzed by formulating an advective-dispersive transport model which incorporates chelate formation, adsorption, decay, and degradation of transporting radioactive solutes. The governing eqautions of the transport model for the radioactive solutes and chelating agents are formulated by introducing the concept of a tenad. Particularly the governing equation for the tenad of radioactive solutes, {M}, is presented as a linear partial differential form and solved analytically by introducing the new extended distribution coefficient, K(D). Specially the transport of chelated radioactive solutes is analyzed by an example calculation. The calculated results from the model show that the transport rate of die tenad {L} is much greater than that of the tenad {M}. This faster transport of {L} may be due to the low retardation factor of {L} comparing to that of {M}. Therefore, it is concluded that the presence of chelating agents even in a small amount greatly accelerates the transport rate of radioactive wastes from a geologic radioactive waste repository.