Gorleben salt dome

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View of parts of the facilities of the exploratory mine at the Gorleben salt dome

The Gorleben salt dome is a salt deposit near Gorleben , Lower Saxony . The deposit was under discussion as a possible repository for high-level radioactive waste until September 28, 2020 . A mine has been built since 1986 to investigate the suitability of the salt dome for final disposal.

properties

The Gorleben salt dome is a large salt dome with a depth of around 300 m to 3500 m. The underground investigations were carried out at a depth of 840 m and 870 m. The saline solution inclusions found in the salt dome today are just as old as the salt rocks that make up the salt dome themselves - that is, older than 200 million years.

costs

Up to now, 90% of the costs of 1.6 billion euros (2013) have been borne by the energy supply companies. The other costs are borne by the federal government and correspond to the proportion of waste from former GDR companies. It is still unclear whether the costs for a new search for a repository (currently planned, as of 2015) will also be borne by the utility companies.

Discussion about the repository and geological investigations

Location selection (1973–1979)

The search for a suitable salt dump began at the end of 1973. A repository for all types of radioactive waste in a salt dome was planned (and still is today) . Salt domes show a high geological stability, often of several hundred million years, are impermeable to gases and liquids, are capable of creeping (can close gaps and fractures through slow deformation) and have a high thermal conductivity . 24 salt domes were considered. The also planned nuclear waste disposal center should also be built at the site of the repository. The federal government commissioned the company KEWA (nuclear fuel reprocessing company) with the search for a location.

On July 1, 1975, KEWA proposed three salt domes in Lower Saxony for closer examination:

Investigations at these sites were stopped in August 1976 due to local protests. The Gorleben site was not considered in this first study due to its proximity to the GDR border and its location in a recreation and holiday area, as explained in the later KEWA study from October 1977 (KWA 1225). According to Lüttig, the Gorleben site did not belong in the cheap category to which the other sites belonged.

The state government of Lower Saxony set up an inter-ministerial working group to examine 140 locations according to extended criteria. First of all, the 23 locations with sufficient capacity were selected. In a second round, 13 remained suitable depending on the depth, population density and competing usage requirements. In the third selection round, criteria such as earthquake risk or air traffic density were considered. From a fourth selection round, the following locations remained for a detailed geological investigation:

In February 1977, the state government of Lower Saxony finally named the Gorleben salt dome as the only location for the repository and the "National Waste Disposal Center (NEZ)". The selection criteria included previous land use, population density , radiation protection and repository geology . Höfer was excluded because of a nearby salt mine, Wahn because of resistance from a neighboring Bundeswehr area, Lichtenhorst, as it was located in the groundwater priority area of ​​Hanover.

During the selection process, it is criticized that geoscientific arguments were only of minor importance. Indeed, only in the first round of selection did geological reasons play the most important role; H. when deciding on the salt dome and when selecting the 140 possible locations. A general geological suitability (size, depth) was, among other things, the basis of the second selection. The Höfer salt dome (Mariaglück), much smaller than the others, was also included on the advice of the Lower Saxony State Office for Soil Research (NLfB). Extensive geological investigations could not be carried out at a large number of locations for cost reasons; instead, suitability is currently only being checked at the Gorleben location.

After Albrecht , then Prime Minister of Lower Saxony, the ultimate decision in favor of Gorleben was made primarily for structural and political reasons for the economic development of the then zone border area . Safety-oriented geoscientific arguments did not play the main role in choosing Gorleben. As the geologist Gert Lüttig who was involved in the selection of the site remembers, the proximity to Morsleben and the GDR repository under construction there also played a role.

Geological exploration

The Federal Institute for Geosciences and Natural Resources (BGR) carries out the geoscientific investigations at the exploration site and evaluates them. The investigations are carried out on behalf of the Federal Office for Radiation Protection (BfS) and in cooperation with the German Society for the Construction and Operation of Repositories (DBE).

Overground exploration (1979–1983)

Entrance to the Gorleben exploration mine

The surface exploration of the Gorleben site began in April 1979 and lasted until 1983. After German reunification, some additional surface work was carried out on former GDR territory from 1992 onwards. Protest actions by local opponents of nuclear power were already directed against the exploration, which occurred in 1979 and 1980 at deep drilling sites 1002 and 1003. On May 3, 1980 about 5000 opponents of nuclear power occupied the deep drilling site 1004 near Trebel , proclaimed the Republic of Free Wendland and built a hut village , which the police evacuated on June 4, 1980.

The investigations mainly comprised 44 salt level boreholes , geophysical investigations, among others. reflection seismic surveys , hydrogeological investigations (500 digestion - and level holes), four deep wells up to 2000 m in the peripheral areas of the salt dome, two Schachtvorbohrungen up to 1000 m depth to confirm the selected slot starting points , a seismic station network to monitor seismic activity and a variety of other investigations, for example long-term pumping tests , hydrological investigations on the receiving waters and geological mapping .

The exploration results and their evaluation were summarized in two reports by the Physikalisch-Technische Bundesanstalt (1983) and the Federal Office for Radiation Protection (1990). Klaus Duphorn worked as an expert for the PTB . Despite the negative exploratory findings, the Gorleben site was still referred to as “suitable”. This was achieved through a change in the safety philosophy: The importance of the overburden as a barrier against the spread of radionuclides was withdrawn and, in return, the salt dome alone was seen as the decisive barrier. On the basis of this change in safety philosophy, underground exploration began. According to research by the Frankfurter Rundschau - published in 2009 - this reduction in security requirements was due to the direct influence of the then new CDU / FDP government under Helmut Kohl .

Underground exploration (1986-2000)

1986 began sinking of shaft 1 , and in October 1996 carried breakdown between the wells 1 and 2 on the 840 m sole . The main aim of the underground exploration is to prove the rock salt parts that are required for final disposal. The position and extent of the main anhydrite and the Staßfurt potash seam are important here, as they represent limits for areas of the salt dome that are suitable for repositories. In particular, the main anhydrite applies because of its widespread gap formation as a potential solution bearer over which the repository absaufen can.

The exploration area 1 is largely open and investigated. Comprehensive geoscientific and geotechnical investigations as well as mining measurements and tests were carried out.

Moratorium (2000-2010)

Entrance sign to the exploration mine and to the Gorleben information center from the BfS

In the agreement between the federal government and the energy supply companies of June 14, 2000, a moratorium was agreed for the planned Gorleben repository in addition to the withdrawal from the use of nuclear power . Thereafter, the exploration in Gorleben was interrupted for ten years (October 2000 to September 2010) to clarify conceptual and safety issues. The mere maintenance costs in this phase amounted to 22 million euros annually and are covered by the waste producers (energy supply companies and research institutes).

The final synthesis report by the Federal Office for Radiation Protection was published in 2005. In December 2006, the then Federal Environment Minister Sigmar Gabriel pointed out that he would resume exploring Gorleben if his concept of comparing locations was accepted.

According to the Frankfurter Rundschau in May 2009, there is an internal paper by the Federal Office for Radiation Protection, according to which “the expansion of the repository had already started in parallel with the exploration”. This report met with a wide response from the public and especially from the opponents of a Gorleben repository. The Federal Office for Radiation Protection, however, denied the existence of the alleged paper and stated that a statement regarding the suitability of the salt dome for a repository could not be made before 15 years at the earliest.

On October 1, 2010, the exploration moratorium was lifted by Federal Environment Minister Norbert Röttgen and the geoscientific investigations continued.

Continuation of geological exploration (2010–2012)

The geological exploration was resumed in 2010 and was interrupted in November 2012 at the request of Environment Minister Peter Altmeier until the 2013 federal election. In the course of the coordination to restart the search for a repository for high-level radioactive waste via the site selection process , the exploration work was stopped on November 6, 2012. The mine will remain open until the location is decided.

Keeping open operation (2014-2021)

After an agreement between the Federal and Lower Saxony Ministry of the Environment on July 29, 2014, the mine will continue to be operated in open mode. The main operating plan 2014 to 2016 with the extension of the approval until the end of 2017 is the basis for the necessary transitional work with which the German Society for the Construction and Operation of Repositories for Waste Materials mbH (DBE) was commissioned. This work also includes renovation and dismantling work (workshops, weather, mechanical and electrical engineering underground, the dismantling of plants and buildings above ground, as well as the reconstruction of the mine site and the reduction of plant security to a standard that is customary in the industry).

Underground dismantling work began immediately and, like the dismantling work on the surface facilities and buildings, were largely completed in the third quarter of 2016. The premises that are not required in the keeping-open operation are to be released from the mountain supervision . The surrounding wall is to be dismantled and the security of the plant is to be reduced. On April 19, 2016, the Federal and State Ministries for Environmental Protection, the Federal Office for Radiation Protection, the State Office for Mining, Energy and Geology as well as the DBE agreed that the transitional work should be completed by the end of 2017 and from January 1, 2018 pure Keep-open operation can begin.

The operator tasks for the Gorleben mine were transferred to the Federal Agency for Final Storage (BGE) based in Peine on April 25, 2017 .

The Federal Environment Ministry (BMU) commissioned BGE to close the mine in September 2021.

Results of the investigations

The results of the above-ground investigations were summarized in two reports by the Physikalisch-Technische Bundesanstalt (1983) and the Federal Office for Radiation Protection (1990). It says (PTB 1983): "An initial assessment of the overburden with regard to its barrier function for potentially contaminated groundwater shows that the clayey sediments that occur over the central areas of the Gorleben salt dome are not so thick and consistently distributed that they would be able to To keep contamination from the biosphere in the long term . "

This assessment is still valid today and is supplemented by other negative site features, for example, selective subrosion , the Gorleben channel filled with mighty groundwater-conducting Quaternary sediments from the Elster glaciation , short transit times of the groundwater from the top of the salt dome to the biosphere. The expectations of the overburden barrier were not met. After these findings, the importance of the overburden as a barrier against the spread of radionuclides was withdrawn by the Kohl cabinet and only the salt dome was declared the decisive barrier.

The previous results of the underground investigations found deficiencies in some areas of the salt dome and can be summarized as follows according to the Federal Institute for Geosciences and Natural Resources (BGR 1998):

  • Core zone of the salt dome with main salt: This is an uncomplicated saddle with no solution or gas deposits. This area is larger than expected in the surface investigations and is well suited for final disposal.
  • The boundary between the core zone and the northern salt dome flank is laid in folds, and the layers involved are largely still in their original sedimentary association. The main anhydrite is broken, but not broken down into individual clods.
  • In the areas near the shaft, in the border area Zechstein 2 / Zechstein 3, there is an intensive folding of the layers with a strong reduction in thickness . In the border area of ​​the Staßfurt potash seam with Zechstein 3, there are some faults that have healed through secondary rock salt . Limited solution and gas deposits can occur in the fault areas, but have no connection to the salt level .
  • In the border between the core zone and the southern flank of the salt dome, the layers involved are very badly deformed and their thickness is reduced. In some areas there is a lack of main anhydrite and accompanying layers. The main anhydrite is broken down into individual clods. Larger isolated solution and gas deposits are possible in the main anhydrite floes.

Overall, the BGR did not give a negative assessment as of 2015: "Despite the fact that the exploration of the Gorleben salt dome has not yet been completed, it can be determined from the previous investigations that from a geoscientific point of view there are no findings against the suitability of the salt dome."

The results compiled by the BGR in the Geological Yearbook Series C , which more modern studies analyze up to 2011, give a positive assessment of the Gorleben site. In particular, "estimates [...] show that the thickness of the geological barrier built up from the host rock, salt, is sufficiently large, even after a period in the order of a million years, to sustainably prevent radionuclide transport from the future repository into the biosphere." A risk from incoming gases and solutions is to be excluded. ”From a geoscientific point of view,“… no findings from the saline against the long-term safety suitability of the Gorleben salt dome for the final storage of radioactive waste ”are available.

Controversy

The moratorium served to clarify conceptual and safety issues. These do not relate to the suitability or unsuitability of Gorleben, but to general questions associated with final disposal, such as the isolation and detection period, gas development, protection goals and safety indicators , multi-barrier concept , host rocks . According to the final synthesis report by the Federal Office for Radiation Protection , there are no clear advantages or disadvantages of one host rock compared to another. Therefore, each location should be checked individually in order to classify it as the relatively best location if necessary. This also applies to Gorleben.

A comparative site assessment was requested by the former Federal Environment Minister Gabriel. In the coalition agreement of 2009 it was agreed to continue exploring Gorleben for its possible suitability to the end.

On the other side are the representatives who are calling for a new location search with a location comparison with the inclusion of Gorleben. This is seen as urgently needed in order to defuse the dispute over Gorleben and to open up new options for action. In addition, a comparative location assessment is necessary for methodological reasons and is already standard in many countries, for example in Switzerland and Sweden. However, in no country has underground surveys been started at more than one location. As in Germany, examinations were carried out over the course of the day; the resulting best location is checked for suitability by means of underground investigations.

In some cases, the requirement was raised to exclude Gorleben from the search for a repository, since the development costs already invested make any neutral assessment impossible.

See also

Web links

Individual evidence

  1. ↑ a b c Gorleben exploration mine, kernenergie.de, April 2013 ( Memento from July 3, 2015 in the Internet Archive )
  2. ↑ a b c d e f g h i Final storage of highly radioactive waste in Germany - The Gorleben final disposal project, Federal Ministry of Economics and Technology, Federal Ministry of Economics and Technology, 2008 ( Memento from June 3, 2016 in the Internet Archive )
  3. ↑ Energy supply companies assume the majority of the costs
  4. ↑ taz: costs for nuclear waste disposal. Four locations for the price of one. 2011, accessed July 8, 2015 .
  5. ↑ German Bundestag, 17th electoral term, recommendation for a resolution and report of the 1st committee of inquiry according to Article 44 of the Basic Law of May 23, 2013
  6. ↑ G. Lüttig et al .: Report of the Barriers Working Group , in: Lower Saxony Ministry of the Environment (Hrsg.): Internationales Endlagerhearing , Braunschweig, September 21 to 23, 1993.
  7. ↑ Samtgemeinde Steimbke: The fight against the nuclear waste storage facility in the Lichtenmoor . In: Samtgemeinde Steimbke . September 30, 2006 ( steimbke.de [accessed July 17, 2020]).
  8. ↑ E. Albrecht: Interview with the Prime Minister of Lower Saxony, Ernst Albrecht, on nuclear power, reprocessing and disposal , Bonn Energy Report of June 6, 1983, pp. 18-21.
  9. ↑ Group Ecology eV / PanGeo - Geoscience Office: study on the development of a basis for a method of selecting repository sites and assessing their long-term safety , the final report on behalf of the Lower Saxony Ministry for the Environment, Hanover, Nov. 1994th
  10. ↑ Gorleben repository only second choice from an expert point of view , interview of the German Depeschendienst with the geologist Gert Lüttig, accessed on November 1, 2009.
  11. ↑ Cold War for the final repository , the daily newspaper of January 11, 2010.
  12. ↑ Tricked, deceived, lied - The Gorleben story , Frankfurter Rundschau of September 22, 2009, accessed in November 2009.
  13. ↑ Gorleben salt dome ( memento of April 8, 2014 in the Internet Archive ), information from the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, July 6, 2009, accessed on December 10, 2009.
  14. ↑ Joachim Wille: Nuclear repository: Schwarzbau Gorleben? ( Memento of May 30, 2009 in the Internet Archive ), Frankfurter Rundschau of May 28, 2009, accessed on December 10, 2009.
  15. ↑ Federal Office for Radiation Protection: Statement on the report of the Frankfurter Rundschau ( Memento from May 31, 2009 in the Internet Archive ).
  16. ↑ stern.de .
  17. ↑ a b c d Gorleben exploration site, BGR, 2015 ( Memento from July 4, 2015 in the Internet Archive )
  18. ↑ a b c Status report on the use of nuclear energy in the Federal Republic of Germany 2016. Federal Office for the Safety of Nuclear Waste Management, Salzgitter, August 2017, accessed on July 14, 2019 .
  19. ↑ International Economic Forum for Renewable Energies: Finding nuclear waste for a final repository: Dealing with Gorleben clarified by 2017. June 15, 2015, accessed July 8, 2015 .
  20. ↑ Gorleben mine is closed. bmu.de, September 17, 2021, accessed on September 17, 2021 .
  21. ↑ Physikalisch-Technische Bundesanstalt : Summary interim report on previous results of the site investigation in Gorleben , Braunschweig, May 1983.
  22. ↑ Geology and hydrogeology of the overburden above the Gorleben salt dome , PDF, 2.29 MB.
  23. ↑ D. Appel & J. Kreusch: The multi-barrier system for the final storage of radioactive waste in a salt dome , study on behalf of Greenpeace Germany, Hanover 2006.
  24. ↑ Geological Handbook Series C, Gorleben site description, part 3, results of the surface and underground exploration of the Salinar , 2011
  25. ↑ Federal Office for Radiation Protection: Conceptual and safety issues relating to the disposal of radioactive waste - host rocks in comparison , synthesis report by the Federal Office for Radiation Protection, Salzgitter, November 2005.

Coordinates: 53 ° 1 ′ 35.5 ″  N , 11 ° 20 ′ 50.9 ″  E