Salt dome Gorleben
Encyclopedia
The salt dome Gorleben is a proposed deep geological repository
in a salt dome
in Gorleben
in the Lüchow-Dannenberg
district in the far north-east of Lower Saxony
for low-, medium- and high-level radioactive waste
.
. 24 salt domes were considered. The federal government asked the company KEWA (Kernbrennstoff-Wiederaufarbeitungs-Gesellschaft) to search for a location.
On July 1, 1975 the KEWA proposed three sites in Lower Saxony for further investigation: the salt domes Lutterloh
, Lichtenhorst and Wahn. The location Gorleben
is not advantageous in this category. The investigation of the sites began with drilling holes. In November 1976 the Lower Saxony cabinet called for the Federal Government to examine the three sites, so they could designate a location.
In February 1977 the Lower Saxony cabinet designated finally the Gorleben salt dome as a single location for the repository and waste disposal center. The choice of Gorleben was the work of a projectgroup which investigated 140 salt domes within a few months.
Of these 140 salt domes only four were proposed: Lichtenhorst, Wahn, Maria Glück
(Höfer) and Gorleben.
Of these Gorleben was chosen. The selection criteria were among others, land use
, population density
, radiation
and repository geology
. Geoscientific arguments played only a small role. For example, the salt dome Höfer (Maria Glück) is too small for a repository but reached the last round of selection. The ultimate decision for Gorleben according to the former Lower Saxony Prime Minister Ernst Albrecht was mainly for structural reasons for the economic development of the zone. 1.5 billion Euro
's of research has been conducted in the period 1979-2000 at Gorleben.
On hindsight it became clear that the original and methodologically correct approach, to investigate three potentially suitable salt domes in parallel and a comparative assessment of the results were abandoned by the choice for Gorleben. Security-oriented geoscientific arguments were ignored in the evaluation of Gorleben. The lack of transparency and accountability for the decision for Gorleben is still one of the reasons why the opposition to the location is so vehemently.
studies, approximately 500 outcrop
- and groundwater
level drillings, four deep boreholes to approximately 2,000 m at the edges of the salt stock, two shaft
boreholes to approximately 1,000 m depth to confirm the starting points of the selected slot, a seismic networkstation to monitor earthquake
activity as well as numerous other studies.
The exploration results and their evaluation were carried out in two reports by the Physikalisch-Technische Bundesanstalt
(1983) and the Bundesamt für Strahlenschutz
(1990) and are summarized below.
It says (PTB 1983): "An initial assessment of the capping mass in terms of its barrier function for potential contaminated ground water shows that the occurring clay sediments in the central areas of the salt stock Gorleben lack the indication that it can function as a permanent barrier to prevent contamination of the biosphere
."
This assessment still applies today and is supplemented by other negative site characteristics, such as anticipatory selective subrosion and the short time that is needed for the groundwater from the salt dome to reach the biosphere.
The expectations that one of the capping masses could be used as a barrier were not fulfilled. After that there was a change in safety philosophy: the importance of the capping mass as a barrier against the spread of radionuclide
s has been withdrawn and in return the salt dome alone is used as the crucial barrier. Based on this modification of the safety philosophy the underground exploration started.
The main objective of the underground exploration is the detection of rocksalts like topanhydrite
which are required for the final storage. The exploration area 1 is largely open and under investigation. Comprehensive geoscientific and geotechnical investigations as well as mountaineering technical measurements and experiments were done. The results so far can be classified according to the Federal Institute for Geosciences and Natural Resources (BGR 1998) as followed:
companies on June 14, 2000 in addition to the nuclear power phase-out
a moratorium on the planned repository Gorleben was agreed on. After the agreement the exploration of Gorleben to clarify conceptual and safety issues was suspended for at least three years with a maximum of ten years.
The prototype for final storage to clarify conceptual and safety issues Schacht Asse II
came in the news in 2008 about brine
contaminated with radioactive caesium-137
, plutonium
and strontium
.
Deep geological repository
A deep geological repository is a nuclear waste repository excavated deep within a stable geologic environment...
in a salt dome
Salt dome
A salt dome is a type of structural dome formed when a thick bed of evaporite minerals found at depth intrudes vertically into surrounding rock strata, forming a diapir....
in Gorleben
Gorleben
Gorleben is a small municipality in the Gartow region of the Lüchow-Dannenberg district in the far north-east of Lower Saxony, Germany, a region also known as the Wendland....
in the Lüchow-Dannenberg
Lüchow-Dannenberg
Lüchow-Dannenberg is a district in Lower Saxony, Germany which is usually referred to as Hannoversches Wendland or Wendland. It is bounded by the districts of Uelzen and Lüneburg and the states of Mecklenburg-Western Pomerania , Brandenburg and Saxony-Anhalt Lüchow-Dannenberg is a district in...
district in the far north-east of Lower Saxony
Lower Saxony
Lower Saxony is a German state situated in north-western Germany and is second in area and fourth in population among the sixteen states of Germany...
for low-, medium- and high-level radioactive waste
Radioactive waste
Radioactive wastes are wastes that contain radioactive material. Radioactive wastes are usually by-products of nuclear power generation and other applications of nuclear fission or nuclear technology, such as research and medicine...
.
Site selection
At the end of 1973 the search began for a final salt dome storage. The plan was a repository for all types of radioactive waste in a salt domeSalt dome
A salt dome is a type of structural dome formed when a thick bed of evaporite minerals found at depth intrudes vertically into surrounding rock strata, forming a diapir....
. 24 salt domes were considered. The federal government asked the company KEWA (Kernbrennstoff-Wiederaufarbeitungs-Gesellschaft) to search for a location.
On July 1, 1975 the KEWA proposed three sites in Lower Saxony for further investigation: the salt domes Lutterloh
Lutterloh
'Lutterloh' refers to a pattern drafting system intended for home sewing developed in Germany in the 1930s. The company, which is family owned, is still in business today....
, Lichtenhorst and Wahn. The location Gorleben
Gorleben
Gorleben is a small municipality in the Gartow region of the Lüchow-Dannenberg district in the far north-east of Lower Saxony, Germany, a region also known as the Wendland....
is not advantageous in this category. The investigation of the sites began with drilling holes. In November 1976 the Lower Saxony cabinet called for the Federal Government to examine the three sites, so they could designate a location.
In February 1977 the Lower Saxony cabinet designated finally the Gorleben salt dome as a single location for the repository and waste disposal center. The choice of Gorleben was the work of a projectgroup which investigated 140 salt domes within a few months.
Of these 140 salt domes only four were proposed: Lichtenhorst, Wahn, Maria Glück
Höfer, Germany
Höfer is a municipality in the district of Celle, in Lower Saxony, Germany.Höfer has an abandoned mine named Mariaglück, about 910 m deep, from which the sum of 13.2 million tons of common salt and potash salt was mined between 1916 and 1977. As the maximum, in 1943 about 241,000 tons of salt were...
(Höfer) and Gorleben.
Of these Gorleben was chosen. The selection criteria were among others, land use
Land use
Land use is the human use of land. Land use involves the management and modification of natural environment or wilderness into built environment such as fields, pastures, and settlements. It has also been defined as "the arrangements, activities and inputs people undertake in a certain land cover...
, population density
Population density
Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans...
, radiation
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...
and repository geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
. Geoscientific arguments played only a small role. For example, the salt dome Höfer (Maria Glück) is too small for a repository but reached the last round of selection. The ultimate decision for Gorleben according to the former Lower Saxony Prime Minister Ernst Albrecht was mainly for structural reasons for the economic development of the zone. 1.5 billion Euro
Euro
The euro is the official currency of the eurozone: 17 of the 27 member states of the European Union. It is also the currency used by the Institutions of the European Union. The eurozone consists of Austria, Belgium, Cyprus, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg,...
's of research has been conducted in the period 1979-2000 at Gorleben.
On hindsight it became clear that the original and methodologically correct approach, to investigate three potentially suitable salt domes in parallel and a comparative assessment of the results were abandoned by the choice for Gorleben. Security-oriented geoscientific arguments were ignored in the evaluation of Gorleben. The lack of transparency and accountability for the decision for Gorleben is still one of the reasons why the opposition to the location is so vehemently.
Surface exploration
The surface exploration of the Gorleben site began in April 1979 and lasted until 1983. The investigation covered drilling 44 boreholes in the salt table, geophysical investigations, including reflection seismic measurements, hydro-geologicalHydrogeology
Hydrogeology is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth's crust, . The term geohydrology is often used interchangeably...
studies, approximately 500 outcrop
Outcrop
An outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. -Features:Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by a mantle of soil and vegetation and cannot be...
- and groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
level drillings, four deep boreholes to approximately 2,000 m at the edges of the salt stock, two shaft
Shaft mining
Shaft mining or shaft sinking refers to the method of excavating a vertical or near-vertical tunnel from the top down, where there is initially no access to the bottom....
boreholes to approximately 1,000 m depth to confirm the starting points of the selected slot, a seismic networkstation to monitor earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
activity as well as numerous other studies.
The exploration results and their evaluation were carried out in two reports by the Physikalisch-Technische Bundesanstalt
Physikalisch-Technische Bundesanstalt
The Physikalisch-Technische Bundesanstalt is based in Braunschweig and Berlin. It is the national institute for natural and engineering sciences and the highest technical authority for metrology and physical safety engineering in Germany....
(1983) and the Bundesamt für Strahlenschutz
Bundesamt für Strahlenschutz
The Bundesamt für Strahlenschutz is the German Federal Authority for Radiation Protection. The BfS was established in November 1989, the headquarter is located in Salzgitter, with branch offices in Berlin, Bonn, Freiburg, Gorleben, Oberschleißheim and Rendsburg. It has 708 employees and an annual...
(1990) and are summarized below.
It says (PTB 1983): "An initial assessment of the capping mass in terms of its barrier function for potential contaminated ground water shows that the occurring clay sediments in the central areas of the salt stock Gorleben lack the indication that it can function as a permanent barrier to prevent contamination of the biosphere
Biosphere
The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth, a closed and self-regulating system...
."
This assessment still applies today and is supplemented by other negative site characteristics, such as anticipatory selective subrosion and the short time that is needed for the groundwater from the salt dome to reach the biosphere.
The expectations that one of the capping masses could be used as a barrier were not fulfilled. After that there was a change in safety philosophy: the importance of the capping mass as a barrier against the spread of radionuclide
Radionuclide
A radionuclide is an atom with an unstable nucleus, which is a nucleus characterized by excess energy available to be imparted either to a newly created radiation particle within the nucleus or to an atomic electron. The radionuclide, in this process, undergoes radioactive decay, and emits gamma...
s has been withdrawn and in return the salt dome alone is used as the crucial barrier. Based on this modification of the safety philosophy the underground exploration started.
Underground Exploration
The drilling for shaft 1 started in 1986 and in October 1996 the punch line was created between shafts 1 and 2 on the 840 m sole.The main objective of the underground exploration is the detection of rocksalts like topanhydrite
Anhydrite
Anhydrite is a mineral – anhydrous calcium sulfate, CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the orthorhombic barium and strontium sulfates, as might be expected from the...
which are required for the final storage. The exploration area 1 is largely open and under investigation. Comprehensive geoscientific and geotechnical investigations as well as mountaineering technical measurements and experiments were done. The results so far can be classified according to the Federal Institute for Geosciences and Natural Resources (BGR 1998) as followed:
- In the border zone between the core and the southern salt dome flank are heavily deformed layers and their thickness is reduced. Areas of missing topanhydriteAnhydriteAnhydrite is a mineral – anhydrous calcium sulfate, CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the orthorhombic barium and strontium sulfates, as might be expected from the...
and accompanying layers. The topanhydrite is decomposed into individual plates. Larger isolated solutions and gas reserves are possible in the topanhydrite layers.
- Between the core zone and the northern salt dome flank the borderzones are laid in folds, and the layers involved are still largely in its original sedimentary form. The topanhydrite is broken, but not decomposed into individual layers.
- Core zone of the salt stocks with topsalt: Here is a simple solution without solutions and gas reserves.
- In the boreholes located in areas near the border area of ZechsteinZechsteinThe Zechstein is a unit of sedimentary rock layers of Middle to Late Permian age located in the European Permian Basin which stretches from the east coast of England to northern Poland...
2/Zechstein 3 intensive folding of the layers with high reduction of thickness occurs. In the border region StaßfurtStaßfurtStaßfurt is a town in the Salzlandkreis district, in Saxony-Anhalt, Germany. It is situated on both sides of the river Bode, approximately northeast of Aschersleben, and south of Magdeburg. Pop. 23,538....
to Zechstein 3 are partially disorders healed by secondary rock salts. Limited solution and gas can occur in the disturbed areas but without connections to the salt levels.
The Gorleben moratorium
In the agreement between the federal government and electric utilityElectric utility
An electric utility is a company that engages in the generation, transmission, and distribution of electricity for sale generally in a regulated market. The electrical utility industry is a major provider of energy in most countries. It is indispensable to factories, commercial establishments,...
companies on June 14, 2000 in addition to the nuclear power phase-out
Nuclear power phase-out
A nuclear power phase-out is the discontinuation of usage of nuclear power for energy production. Often initiated because of concerns about nuclear power, phase-outs usually include shutting down nuclear power plants and looking towards renewable energy and other fuels.Austria was the first country...
a moratorium on the planned repository Gorleben was agreed on. After the agreement the exploration of Gorleben to clarify conceptual and safety issues was suspended for at least three years with a maximum of ten years.
The prototype for final storage to clarify conceptual and safety issues Schacht Asse II
Schacht Asse II
The Asse II pit is a former salt mine used as a deep geological repository for radioactive waste in the mountain range of Asse in district Wolfenbüttel in Lower Saxony, Germany.-History:...
came in the news in 2008 about brine
Brine
Brine is water, saturated or nearly saturated with salt .Brine is used to preserve vegetables, fruit, fish, and meat, in a process known as brining . Brine is also commonly used to age Halloumi and Feta cheeses, or for pickling foodstuffs, as a means of preserving them...
contaminated with radioactive caesium-137
Caesium-137
Caesium-137 is a radioactive isotope of caesium which is formed as a fission product by nuclear fission.It has a half-life of about 30.17 years, and decays by beta emission to a metastable nuclear isomer of barium-137: barium-137m . Caesium-137 is a radioactive isotope of caesium which is formed...
, plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...
and strontium
Strontium
Strontium is a chemical element with the symbol Sr and the atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when exposed to air. It occurs naturally in the minerals celestine and...
.