It takes a very long time for ionizing radiation of used nuclear fuel toreturn to a natural background level, for this reason one of the requirements for theselection of the location of a repository was that the environment as well people'shealth would be protected from the harmful effect of radioactivity. This requirementmeans that the waste must be isolated in a geological formation. In Sweden therepository will be built in the crystalline bedrock. The location for the Swedish nuclearfuel repository at nearly 500 meters depth at Forsmark in Östhammar was decided 3June 2009. The repository will be located at Söderviken, close to the Forsmarknuclear power plant in a 1.90 billion year old bedrock that will accommodate 12,000tons of spent nuclear fuel. The bedrock of Östhammar is a seismically quiet, howeverthere is a large system of fracture zones and fractures at the site considered to havebeen formed shortly after the ductile shear zone deformaton. The geology isdominated by medium grained metagranite with mafic intrusions. These rock volumeshave been subjected to metamorphism and ductile deformation at c. 1.85 Ga.The site investigations shown that the bedrock composition was asexpected, except for a few locations of a porous granite (episyenite) and a fracturedbedrock down to about 200 meters depth. This rock is relatively uncommon, but mayaffect the quality of the repository. Most episyenites are geographical associated tofractures and fracture zones, but there are exceptions where there are no distinctrelationships to the latter.