Radionuclide Transport in Geologic Waste Repository: Application of Compartment Models

Analyses of radionuclide transport in geologic radioactive waste repository are made for a water-saturated repository and an unsaturated repository. To deal with the transport problem at the repository scale with multiple nuclide sources, compartment models are developed. The models allow us to observe the effects of repository layout on the performance of waste disposal system, and thus can be applied for making comparisons among various designs of repository layout. Residence times of radionuclides in individual components are found to be the key parameters in the present analysis, and the peak concentration of the radionuclide in the groundwater is formulated in terms of the residence times. Compartment models are further developed in integration with stochastic processes in order to reflect two- and three-dimensional transport and to incorporate residence time distributions obtained from an analysis at a sub-compartment scale. The models and the analysis should be useful to researchers engaged in performance assessment of radioactive waste repository as well as environmental scientists modeling contaminant transport in groundwater.