Aspects on the gas generation and migration in repositories for high level waste in salt formations / GRS, Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbH ; André Rübel, Dieter Buhmann, Artur Meleshyn, Jörg Mönig, Sabine Spiessl ; this report was prepared under contract No. 02 E 10719 by the Federal Ministry of Economics and Technology (BMWi)