Retardation Factor of a Radionuclide for Undisturbed and Disturbed Sandy Soil

The relationship of the retardation factor of a radionuclide for undisturbed soil and that for disturbed soil has been investigated. The migration model is based on the assumption that both reactive (dynamic) and nonreactive (stagnant) sites exist in the soil column. The retardation factor for undisturbed soil is represented by the following equation:Rf_u ⁼ S_u/S_dRf_d ,where Rf_u and Rf_d are retardation factors for undisturbed and disturbed soil, respectively, and S_u and S_d are degrees of water saturation in undisturbed and disturbed soils, respectively. The migration experiments for both the undisturbed and disturbed soil columns were carried out using ⁸⁵Sr. The average retardation factor for the undisturbed soil is smaller than that for disturbed soil, and the degree of water saturation in the undisturbed soil column is smaller than that in the disturbed soil column. The retardation factor for the undisturbed soil estimated, based on the above equation, is approximately the same as the measured retardation factor for the undisturbed soil.