IN SITU TRACER TESTS TO DETERMINE RETENTION PROPERTIES OF A BLOCK SCALE FRACTURE NETWORK IN GRANITIC ROCK AT THE A SPO HARD ROCK LABORATORY, SWEDEN

Experiments were conducted in order to improve the understanding of radionucleide retention properties of fractured crystalline bedrock in the 10–100m scale. A series of tracer experiments were performed using sorbing tracers in three different flow paths (14, 17 and 33m). Four tests were performed using different cocktails made up of radioactive sorbing tracers. The results of the modelling indicated that there is a slightly higher mass transfer into a highly porous material in the block-scale experiment compared with in situ experiments performed over shorter distances and significantly higher than what would have been expected from laboratory data obtained from studies of the interactions in non-altered intact rock.