For the long-term safety assessment of a repository of a deep underground repository for radioactive waste, the detailed knowledge of the geological system, an extensive geomechanical, geohydraulic and geothermal as well as geochemical database and a powerful numerical code validated with the data from the in-situ experiment are necessary. How well these codes can predict the processes taking place after the closure of the repository can only be proven using large-scale experimental data, e.g. FEBEX project, which is relevant to a real repository.

The project EFP performed in the BK area at the GRIMSEL TEST SITE (GTS) makes it possible to carry out a large-scale tracer transport experiments in the fractured rock to 'up-scale' the model in temporary and spatial sense and to estimate the effective parameters for the model.

Three different codes were examined: ROCKFLOW, SPRING AND TOUGH2 for the predictive modelling and design calculations of the large scale test in the BK area.

Predictive modelling of the tracers

Comparative predictive modelling of tracer tests: