The Gorleben facility is located in an undisturbed salt dome near the village of Gorleben approximately 100 km southeast of Hamburg, Germany. Fol­lowing the selection of the Gorleben site in 1977 for investigation as a poten­tial repository for heat-generating wastes, and the establishment of DBE in 1979, a comprehensive surface-based investigative programme was initiated to characterize the salt dome and the surrounding area of the site. Based on the positive indications from the surface investigations, an underground exploratory facility was designed and constructed by DBE in 1986 on behalf of the BfS. The Gorleben exploratory facility was intentionally designed to facilitate conversion to a repository, assuming subsequent investigations would continue to support the site’s suitability. From 2000 to 2010, site char­acterization activities at Gorleben were suspended by the federal govern­ment as part of a moratorium agreement negotiated between the previous government and the nuclear industry. In October 2010 the moratorium expired and site characterization and licensing activities were restarted.

In the 1980s and 1990s, considerable effort was invested in investigating the Gorleben salt dome as a potential site for hosting a nuclear waste repository. The investigations supported the concept of rock salt as a host environment based on its very low inherent permeability and the self­healing nature of fractures due to the plastic response behaviour of the rock type. In addition to the subsurface research facility, many of the surface installations were also completed prior to the imposition of the ten-year moratorium. In the framework of research, development and demonstra­tion activities, significant advances have been made with respect to proto­type equipment development, including development of a shaft hoist system with a capacity to lift 85 tonnes, emplacement machines for both drift and borehole disposal, and equipment for backfilling disposal drifts. For these reasons, the facility at Gorleben is unique when compared to other inter­national repositories in that much of the site characterization and surface infrastructure work was actually completed in the 1980s and 1990s. As a result, despite the moratorium, Gorleben remains one of the most techni­cally advanced potential high-level RAW repository sites currently under consideration both in a national and international sense. Figure 14.7 shows the potential Gorleben repository concept and existing prototype equipment.

Shaft transport

Borehole emplacement

Backfilling slinger truck in a disposal drift

Drift emplacement

14.7 Gorleben repository concept with prototype shaft hoist, borehole emplacement machine, backfilling slinger truck and drift emplacement machine. Source: Provided by the German Company for the Construction and Operation of Waste Repositories (DBE), Peine, Germany.

Since the moratorium was lifted and research was recommenced, new safety requirements for the disposal of heat-generating waste, as well as requirements for retrievability have been published and are expected to be enacted. The performance criteria include the evaluation of repository safety for a one million-year period (referred to as the period of geological stability) at an annual effective exposure not to exceed 10 pSv for likely event scenarios and 100 pSv for less likely events (BMU, 2010). However, recent legal actions challenging key aspects of the operating licence for the Gorleben site investigation, submitted to the Upper Administrative Court of Luneburg, have resulted in the suspension of on-going subsurface research activities at Gorleben with immediate effect pending further judi­cial review.

A preliminary safety assessment (vorlaufige Sicherheitsanalyse fur den Standort Gorleben, VSG) that will provide a detailed evaluation of the potential suitability of the Gorleben salt dome as a repository host formation for the disposal of heat generating waste is currently being com­pleted. The Gesellschaft fur Anlagen — und Reaktorsicherheit (GRS) is responsible for developing the VSG in collaboration with a team of con­tributing organizations, and is scheduled to be completed in 2013.