Abstract:
This progress report introduces the development of the disposal systems evaluation framework (DSEF), a tool created by the Lawrence Livermore National Laboratory (LLNL) to formalize the design and documentation of conceptual repository options for nuclear waste disposal. The DSEF consists of a user-friendly Microsoft Excel workbook for a single design and a Microsoft Access database for compiling results from multiple designs. The DSEF is designed to guide a user through developing an internally consistent repository design, documenting decisions, and identifying inconsistencies by linking various worksheets on topics like waste forms, environments, thermal management, and cost. A key function of the DSEF is its ability to interface with external models for thermal analysis. The DSEF can use simple analytic models in commercial off-the-shelf software like Mathcad, but it also has an interface with a more complex finite element thermal code, TOPAZ3D. This report details how TOPAZ3D works with a mesh generator, TrueGrid, to create meshes for complex geometries like multi-layered parallelepipeds and concentric cylinders, which represent waste packages and repository regions. To validate this approach, a simple thermal simulation of an aluminum parallelepiped was conducted, and the results from the TOPAZ3D finite element model were compared to a Mathcad analytical solution, demonstrating good agreement, although the finite element solution was highly sensitive to mesh size. The DSEF will document these thermal calculations, including inputs from external programs like TrueGrid and TOPAZ3D, and will serve as a central location for documenting and comparing performance assessment models and results.
