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.