Thermohydrological Conceptual Model Evaluation Using Laboratory- and Field-Scale Heater Tests

Coupled heat and mass transfer observations and measurements from heater tests conducted at two scales, laboratory and field, provide a basis to evaluate thermohydrological conceptual models. The U.S. Department of Energy is conducting a long-term drift-scale heater test (DST) as part of a comprehensive evaluation of a proposed geologic high-level nuclear waste repository at Yucca Mountain, Nevada. Laboratory-scale heater tests conducted at CNWRA provide results of similar heat and mass transfer processes, but at a different scale. Comparison of results from tests at different scales provides an opportunity to examine different conceptual models for matrix-fracture interactions expected at the proposed repository. Conceptual models used for heat and mass transfer between the fractures and matrix are evaluated because they have been found to have a profound effect on simulations of thermohydrological processes. In addition, the effects of selected property (i.e., matrix and fracture permeability, thermal conductivity, and the air-entry pressure) values are evaluated in terms of their importance to the evolution of temperature and saturation in the simulations. The multiphase simulator, MULTIFLO, was used to perform the conceptual model evaluations. Simulated temperature and fracture saturation were used to compare the ability of the conceptual models to replicate the laboratory- and field-scale results and the importance of the property values assigned to key parameters in the numerical models. This abstract is an independent product of the CNWRA and does not necessarily reflect the views or regulatory position of the NRC.