Nonequilibrium fracture-matrix flow during episodic infiltration events in Yucca Mountain

This report examines the impact of nonequilibrium fracture-matrix flow on episodic infiltration events in Yucca Mountain. For both the FMMM and ECM calculations, a ponded boundary condition is maintained at the repository horizon until the liquid front has broken through to the water table. The relative impact of matrix imbibition is examined for the five major hydrostratigraphic units between the repository horizon and the water table. The question of what sequencing of infiltration events gives rise to episodic behavior versus behavior which may be time-aggregated is also addressed. The implications of nonequilibrium fracture-matrix flow on radionuclide transport are briefly discussed. 19 refs., 7 figs., 5 tabs