The safety of a deep repository for radioactive waste at any site is determined both by the characteristics of the site and of the repository design. The process used to select the site only partly determines its safety. The safety of a potential repository at a specific site can only be assessed after investigations that provide site-specific data. It then becomes possible to address the questions:
• Was the site properly chosen?
• Can the site provide the required level of
safety? The first question cannot be addressed purely scientifically; societal, economical and political issues also affect the selection of a site. The ILK believes that there are several suitable sites in Germany and that the selection process cannot be solely reduced to a geological problem. The second question can, in principle, be answered using the existing safety assessment methodology that has been developed internationally over the past 25 years – provided that the data necessary for the assessment is available in sufficient quantity and quality.
The Gorleben site was selected according to the scientific, societal, economic and political knowledge and guidelines of the time, both in Germany and across Europe. The process was not in line with the processes currently required as part of an environmental impact assessment (EIA) under environmental laws promulgated in several countries during the 1990s. The allegation that the selection process itself disqualifies the site does not have any scientific basis.
After the selection of Gorleben as a potentially suitable site in 1977, an extensive site characterisation programme was conducted from the ground surface and from underground. This programme was more extensive than for any other potential repository site in Europe. Only the two US projects at WIPP in New Mexico and Yucca Mountain have undertaken investigations on a similar scale. An extensive database has been collected. The results obtained so far provide no technical grounds for ruling out the site or interrupting the planned site characterisation programme, but the data remains incomplete. Completion of the activities that were planned before the start of the current moratorium would have provided a more complete database that could be used for a qualified scientific judgement of the suitability of Gorleben as a site for a deep geological repository.
The German government has published a list of scientific and technical issues that it claims must be resolved before any site investigations proceed at Gorleben. These issues have been reviewed by the ILK, which believes that the list of issues mostly represents topics that are actively discussed in the international scientific community.
Some of the problematic issues require further clarification as part of a continued programme at Gorleben, for example gas production and transport. The most important and constructive scientific and technical approach would firstly involve compiling the available data in a total systems performance assessment (TSPA) for a potential repository at the Gorleben site. Such an assessment has not yet been made.
Significant quantities of spent fuel and some high level waste from reprocessing is at present stored at various places in the country and should be prepared for final disposal. The important task of final disposal of radioactive waste should be managed by our generation and not handed over to a future generation. However, a deep repository project has a very long lifespan, perhaps 50 or 60 years. During this time the knowledge and amount of data available for a site will increase continuously once site investigations have started. The methodology for the TSPA is under continuous development. The TSPA must therefore be updated and revised from time to time. As an example, the TSPA of the Swedish repository for low and intermediate level radioactive wastes was recently updated using new methodologies, as well as experiences and data from ten years of operation. Equally important is that the repository project proceeds in steps and that each step includes updates of the TSPA.
Scientific and technical motives for stopping, or stepping back from, a repository project should be founded either in a modern TSPA or by the discovery of clearly disqualifying properties of the site being investigated. Neither seems to exist for the current Gorleben moratorium. It remains a political or societal decision whether the investigation in preparing and investigating a potentially suitable site should be written off.
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