This study presents the results of numerical calculations that estimate the repository's geometrical settings taking into account the thermal impact of the stored high-level radioactive waste. It compares the design implications of a generic repository with retrievability and monitoring in four host rocks: rock salt, clay, shale and crystalline hard rock. Early examples of research into repository design based only on empirical values assume that due to the retrievability arrangements a bigger emplacement field area is required. To verify this assumption by means of numerical simulations, a generic repository model with drift emplacement for each host rock was proposed and the simulations were carried out using the software FLAC3D. Key factors are the heat decay released by the High-level-Waste (HLW), the interim storage period of the HLW after removal from the reactor and the cask loading. These were taken into consideration for the simulation.