FORGE, Fate of Repository Gases: because of corrosion processes or due to the metabolism of microbes that are present, the metals and organic substances stored in a deep geological repository produce gases such as hydrogen and methane in the storage galleries. In dense host rocks, this gas can only be removed slowly, so pressure builds up in the storage galleries. The important question as regards the long-term safety of a deep geological repository is whether this build-up of pressure jeopardises the retention capacity of the host rock due to the formation of fissures.

FORGE is an EU project with 24 participants. It aims to investigate the importance in relation to safety of the processes caused by gases in the near and far field of a deep geological repository. The work is divided into five sub-programmes (known as Work Packages, or WP). In 2009, ENSI collaborated on WP1 (treatment of gas in safety analyses). This work includes compiling an inventory of technical and scientific knowledge regarding the gas problem, defining comparative calculations regarding gas transport, and carrying out safety-relevant calculations. In 2009, the project participants compiled an overview report on the importance in terms of safety engineering of the processes caused by gases in the near and far fields of a geological repository. In addition, the comparative calculations were defined in the working group.