On-line method for measurement of the dispersion coefficient of radionuclide migration using a column method

An on-line method to obtain breakthrough curves from a conservative tracer generated in crushed rock columns has been introduced. The breakthrough curve can be used to evaluate some important hydrologic parameters for studying radionuclide migration in groundwater system. These parameters include the dispersion coefficient, avarage flow velocity, effective porosity, and retardation factor of the columns tested. A conservative radiotracer, 131I, was used to generate the breakthrough curves, and linear regression analysis was applied to obtain the optimum value of dispersion coefficient. The effects of the injected volume of radioactive tracer, average flow velocity, and effective diameter of packed material on the dispersion coefficient as well as the stability of the packed material, and their in-situ application are discussed. (author) 10 refs.; 4 figs.; 2 tabs