Evolution of temperature and humidity in an underground repository over the operation period

Abstract

Abstract The aim of the study is to describe the ambient conditions in an underground repository of nuclear waste over a 100-year-long operation period. The evolution over time of the moisture and the temperature in the ventilation network was assessed by means of numerical simulations. Condensation events are described in terms of location, frequency and flow rate. The physical conceptual model takes into account the heat and vapour advection and exchanges with walls, and heat conduction through the host rock. The results of simulations were analysed to highlight how the architectural design, the gradual extension of storage zones, the ventilation rate and the weather conditions are likely to influence the ambient conditions all along the shafts, the galleries and the storage modules. They illustrate the significant effects on ambient conditions of the wall thermal inertia, the variation in atmospheric pressure over the shaft height, and the ventilation partition in some galleries between incoming and outgoing air from storage modules.