Nagra’s Grimsel Test Site – Testing a gas-permeable seal for deep geological repositories
Wettingen, 1th June 2012
Guttannen (Bern) – A multi-year, large-scale demonstration experiment has started at Nagra’s Grimsel Test Site, with the aim of confirming important aspects of the functioning of tunnel seals in future geological repositories. The experiment seal consists of a clay (bentonite)/sand mixture and will be used to demonstrate the feasibility of controlled gas transport from a radioactive waste repository on a realistic scale.
Nagra began operating the Grimsel Test Site, an underground rock laboratory located at an altitude of 1730 metres in the Swiss Alps, 28 years ago. Numerous experiments have already been carried out on the construction and safe operation of future geological repositories for radioactive waste. A new milestone in the history of the Grimsel Test Site was reached in May: the completion of the construction and the start of the operation of the GAST (Gas-Permeable Seal Test) experiment, which investigates the emplacement and behaviour of the seals (barrier) for future geological repositories.
The Grimsel Test Site is located at an elevation of 1730 metres above sea-level in 300 million year old granite and granodiorite of the Aar Massif, at a depth of around 400 m beneath the Juchlistock. Cored boreholes with a total length of around 5000 metres have been drilled to date in the branching research tunnel system, which extends over more than 1 kilometre. Organisations from 11 countries and the EU are involved in the Grimsel experiment programme. Year-round access to the facility is assured for the scientists involved in the experiments, in winter with a cable-car. The Test Site is open to visitors by prior arrangement from the beginning of June to the end of October.