Development of geologic repository models for design and decision making

Murakami, Haruko*; Ahn, J.*

This paper presents a new radionuclide transport model for performance assessment and design of a geologic repository for high-level radioactive wastes. The model applies compartmentalization and a Markov-chain approach. A model space consists of an array of compartments, among which radionuclide transport is described by a transition probability matrix. While the model is similar to Eulerian methods, the advantages of this approach are considered in flexibility in including various types of transport processes by probabilistic interpretation. We demonstrate this model approach with a hypothetical repository assumed in porous rock formation. A three-dimensional, non-uniform groundwater flow field is generated numerically by the finite element method. The transition probability matrix is constructed based on the velocity field and hydraulic dispersion coefficients. The results show that this transport model can effectively show differences in repository performance due to the change of hydraulic properties in the domain for differing repository configurations and material degradation.