Publications

Abstraction of Thermal Hydrology and Coupled Processes for TSPA

Itamura, Michael T.; Francis, Nicholas D.

The thermal-hydrologic (TH) and coupled process models describe the evolution of a potential geologic repository as heat is released from emplaced waste. The evolution (thermal, hydrologic, chemical, and mechanical) of the engineered barrier and geologic systems is heavily dependent on the heat released by the waste packages and how the heat is transferred from the emplaced wastes through the drifts and through the repository host rock. The essential elements of this process are extracted (or abstracted) from the process-level models that incorporate the basic energy and mass conservation principles and applied to the total system models used to describe the overall performance of the potential repository. The process of total system performance assessment (TSPA) abstraction is the following. First is a description of the parameter inputs used in the process-level models. A brief description is given hereof past inputs for the viability assessment (e.g., for TSPA-VA) and current inputs for the site recommendation (TSPA-SR). This is followed by a highlight of the process-level models from which the abstractions are made. These include descriptions of TH, thermal-hydrologic-chemical (THC), and thermal-mechanical (TM) processes used to describe the performance of individual waste packages and waste emplacement drifts as well as the repository as a whole. Next is a description of what (and how) information is abstracted from the process-level models. This also includes an accounting of the features, events, and processes (FEPs) that are important to both the regulators and the international repository community in general. Finally, an identification of the TSPA model components that utilize the abstracted information to characterize the overall performance of a potential geologic repository is given.