Site selection
- Which options are available for repository sites?
- Why was a "Repository Commission" established?
- Start of the selection process
- What steps are involved in the site selection process?
- What role does the BGR play in the site selection procedure?
- Which host rocks are being considered in the site selection process?
Gallery in the Mont Terri Rock Laboratory (Switzerland). BGR here investigates since 20 years the properties of claystone as a host rock for a repository
Source: BGR
Which options are available for repository sites?
The search and selection of a site for a repository for heat-generating radioactive waste was regulated since July 2013 by the "Act governing the search and selection of a site for a repository for heat-generating radioactive waste", which has been replaced by the "Act governing the search and selection of a site for a repository for high-level radioactive waste" (Site Selection Act - StandAG).
In a new multi-phased comparative process, the site with the "best-possible safety" is to be determined, and then defined by an act of parliament. One of the new aspects here is increased public involvement right from the start of the process. Every step of the procedure must be transparent and comprehensible. The potentially suitable host rocks salt, claystone and granite for a repository for radioactive waste in Germany will be taken into consideration as part of this process.
Why was a "Repository Commission" established?
Pursuant to Section 3 of the StandAG, the Bundestag and Bundesrat established a commission in 2014 whose job was to make the necessary preparations for the actual search for a repository site. The members of the "Storage of high-level radioactive waste" Commission (Repository Commission) included politicians from the Bundestag and the Länder governments, as well as representatives of science and society. The 34-member commission chaired by Ursula Heinen-Esser and Michael Müller, worked for two years to elaborate scientific and societal recommendations for action.
As the federal government's consultant on geoscientific issues involving repositories, BGR provided technical advice to the Repository Commission. BGR experts were present as permanent guests at every meeting of the commission. BGR submitted numerous expert reports and independent opinions. The topics included the geoscientific criteria for repository site selection in other countries (K-MAT 23a, download in German), and easily understandable facts on claystone and clay research (K-MAT 16, download in English).
The Repository Commission finished its work with the hand-over and presentation of its final report at the beginning of July 2016. In its 681-page final report (K-Drs. 268, download in German), the commission states its position on aspects including:
- other disposal options
- general safety requirements
- geoscientific exclusion criteria, minimum specifications and assessment criteria
- planning science criteria
- preliminary safety analyses
- criteria for the potential correction of errors during the course of the process
- organisational structure and public involvement
The Repository Commission recommends deep-geological storage as the means of disposal. The geoscientific criteria elaborated by the commission in this report will guide the comparative selection process. This means that the criteria used to select a site with the "best possible safety" have already been defined before the selection process begins. The process is also intended to offer possibilities for correcting errors by the recoverability and retrievability of the waste.
Start of the selection process
The selection process for a repository site for heat-generating nuclear waste was launched by Federal Minister for the Environment, Nature Conservation, Building and Nuclear Safety Barbara Hendricks on 5 September 2017.
What steps are involved in the site selection process?
The Act on the Search and Selection of repository sites for heat-generating nuclear waste regulates the site selection procedure (Site Selection Act – StandAG of May 2017).
Starting from the entire federal territory – from a white map of Germany – the site regions to be explored are identified by means of criteria and requirements specified in the Act. Only in the course of site selection procedure it will be possible to determine which regions in Germany are considered to be worthy of investigation after all of these criteria and requirements have been applied. In Germany, the host rocks rock salt, claystone and crystalline rock are generally considered for the final disposal of high-level radioactive waste.
The Federal Company for Radioactive Waste Disposal (BGE) is responsible for the implementation of the site selection procedure.
The site selection procedure starts with the identification of partial areas based on the geoscientific exclusion criteria, minimum requirements and the geoscientific weighing criteria. This is followed by a comparative analysis based on existing data applying representative preliminary safety analyses and reapplying the geoscientific weighing criteria to identify the site regions with a favorable overall geological setting. In addition, scientific planning critera are also applied. The implementor BGE submits a proposal on the site regions which have to be explored from the surface. Once the site regions to be explored on the surface have been identified, the surface exploration is carried out by means of drilling and seismic surveys. On the basis of the exploration results, the implementor conducts further-developed preliminary safety analyses and socioeconomic potential analyses. On the basis of the results and by reapplying the requirements and criteria set out in §§ 22-24 StandAG, favourable sites are identified. This is followed by the renewed application of scientific planning criteria.
Based on the exploration results, the implementor proposes sites for underground exploration. After the decision on the sites to be explored underground is made, the exploration of underground sites at these locations follows (construction of mines and underground investigations). On the basis of the results of the exploration, the implementor carries out comprehensive preliminary safety analyses. The implementor identifies sites by applying again the requirements and criteria according to §§ 22 to 24 StandAG. Once again, scientific planning criteria are also applied.
This is followed by a subsequent site comparison and a proposal of the implementor, which is submitted to the Federal Office for Safety of Nuclear Waste Management (BASE). The BASE performs regulatory tasks of the Federal Government of final disposal. It reviews the proposal, including the underlying site comparison of at least two sites, assesses which is the site with the best possible safety and forwards the result to the Federal Ministy for the Enviroment, Nature Conservation and Nuclear Safety (BMU). The acceptance of the proposal is decided by federal law.
According to the StandAG, the site selection process should be completed by 2031. The repository commission has the opinion that the emplacement of high-level radioactive waste at the chosen site with the "best possible safety" will not begin until 2050.
What role does the BGR play in the site selection procedure?
In the site selection procedure, the BGR plays a qualified advisory role for the implementor, the Federal Company for Radioactive Waste Disposal (BGE). On the basis of a cooperation agreement (link in German), it advises BGE on the implementation of the geoscientific part of the Site Selection Act.
Which host rocks are being considered in the site selection process?
Salt
Salt structures in north Germany
Source: BGR
The nature, composition and properties of the rocks at the repository sites primarily determine how well these natural barriers protect the environment from radiation. Rock salt has particularly good isolating properties for high-level radioactive heat-generating waste in particular.
BGR has gained a leading international reputation in the exploration of salt domes as potential repository formations for radioactive waste. BGR published a geological map on the salt structures in north Germany in 2008. The "Salt structures of north Germany" map at a scale of 1:500,000 is the first overall map of all of the approximately 450 salt domes, salt pillows and salt formations in north Germany, including the German sector of the North Sea.
BGR compiled a catalogue in 1994 describing the salt structures in Germany, and evaluated them in terms of their potential as repository sites. This salt study (download PDF, 6.3 MB, in German) was not, however based on the new criteria which have now been developed. The salt study was published by the Repository Commission as K-MAT 5.
Claystone
Map of rock salt and claystone formations deemed worthy of investigation in Germany in previous studies
Source: BGR
In addition to salt formations, other potential host rocks, such as claystone formations, are also being investigated to assess their suitability for a nuclear repository. BGR carries out these investigations on the basis of international co-operation projects in underground laboratories, primarily in Switzerland and France. This work involves developing and testing methodologies and equipment for the geoscientific exploration of potential repository sites. Another objective of the work is to extrapolate the findings from the joint international projects to analogous geological formations in Germany.
BGR was authorised by the former Federal Ministry for Economic Affairs and Energy (BMWi) in 2003 to implement a study on the distribution of claystones as potential host rocks for a repository for high-level radioactive waste in Germany. This clay study (download PDF, 16 MB, in English) with the title "Final disposal of radioactive wastes in deep geological formations of Germany. Investigation and evaluation of argillaceous rock formations" was published on 18.04.2007. However, the clay study was not based on the new criteria of the selection process.
The investigations used to study the claystone formations are based on the internationally recognised exclusion and assessment criteria formulated by BGR for the salt and crystalline host rocks. Investigations were supplemented by the host-rock-independent exclusion criteria and minimum requirements defined in 2002 by the Committee on a Site Selection Procedure for Repository Sites (AkEnd). In addition, BGR also included in its original selection process other assessment criteria considered to be crucial from a geoscientific point of view. The evaluation was based on all of the available data in maps, archive material and boreholes. No field work was carried out. The clay study was published by the Repository Commission as K-MAT 6.
Crystalline rocks
BGR published a catalogue in 1995 of the crystalline rock formations in Germany worthy of further investigation for the disposal of high-level heat-generating radioactive waste: the crystalline rock study (download PDF, 2 MB, in German). The crystalline rock study was published by the Repository Commission as K-MAT 4.
The summary report "Investigation and evaluation of regions with potentially suitable host rock formations" (download PDF, 1.2 MB) summarises the research findings on the host rocks in Germany: rock salt, crystalline rocks and claystones. The summary report was published by the Repository Commission as K-MAT 7.
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