USING TOUGH2-GRS FOR MODELLING C-14 TRANSPORT IN A REPOSITORY

摘要

The TOUGH2 code was modified by GRS with several repository-relevant processes (called TOUGH2-GRS) and used as a code for simulating multi-phase flow in porous media. For code development and quality assurance, an extensive program was implemented to demonstrate the correctness and reliability of TOUGH2-GRS. The LLW/1LW repository "Endlager fur radioaktive Abfalle Morsleben (ERAM) " located in Saxony-Anhalt, Germany, was chosen to evaluate the impact of grid complexity on the results obtained by two-phase flow calculations with TOUGH2-GRS for C-14. Three grids with increasing complexity regarding spatial resolution and including multiple mine levels were generated and compared with single-phase-flow calculations with parameter datasets for ERAM, taken from the application for its decommissioning, which is currently under review. The discharge of relevant nuclides is in all cases below the discharge modeled by single-phase simulations. The calculated discharge of C-14 depends on the complexity of model grids. The highest release of C-14 was calculated for the grid with medium complexity for a scenario with significant brine entry.