The Full-Scale Emplacement Experiment, or the FE Experiment in short, has now entered the actual monitoring phase and a glimpse of what is happening behind the concrete plug will now be impossible for years, or even decades. The engineers had already started heating the rearmost container while the granular bentonite mixture was still being filled in around the front container. The scientists gradually brought all the systems in the dummy containers up to speed and the first measurements from the several hundred sensors installed on and around the containers are now being analysed on computers at the head office in Wettingen. The aim is to determine how temperatures, humidity, pressure, deformations, gas composition, permeability, etc. will evolve in the granular bentonite mixture and the surrounding rock in the coming years.