Migration experiments in a single fracture in the Stripa granite. Preliminary results

Within the Stripa project flow and sorption in a readily identifiable fracture which can be excavated for a detailed examination of the flow path and sorption sites is under investigation. The experiments are performed in the Stripa mine, 360m below ground, where there is a natural water flow towards the drift. The bedrock is granite. A method of tracer injection into a fracture, either as a step or a pulse, and of collection of water samples under anoxic atmosphere has been tested in a preparatory investigation. The introduction of tracers is done by injection with over pressure. Injections of Rhodamine-WT, Na-iodide and Uranine have been performed. It has been found that Rhodamine-WT is influenced in some way along the flow path. Another fissure system has been chosen for the main test. In this sorbing tracers will also be used. So far tests for connectivity and a tracer test using Uranine has been made