Final storage refers to the disposal of waste by placing it in a specially designed facility, the final storage facility . The term is mainly used in connection with the storage of radioactive waste - nuclear final storage - but is basically applicable to all types of waste, including the sequestration of CO₂ .
According to the definition, recycling or reprocessing of the waste in the case of final disposal is normally not provided, unless specific precautions are taken to be able to retrieve the waste from the final disposal if necessary; in this case one speaks of retrievable final storage. The defining difference to interim storage (especially important for atomic interim storage ) is the duration of the license granted; Similar requirements are placed on the technical quality of the storage; With both types of storage there is a need to monitor, control and repair any damage that may occur.
Since the beginning of the industrial age and also due to the strong population growth in the last two hundred years, more and more toxic substances have been used on earth, arise as a by-product of economic goods or remain at the end of the useful life of a product if there is no reuse or recycling. This waste is disposed of in different ways, depending on how dangerous it is. In the past they were partly disposed of by pouring them into bodies of water (" dumping ") or by letting liquid waste seep into the ground. This led to water pollution and polluted soils (see contaminated sites , soil remediation ). The first German waste law ("Law for the Avoidance and Disposal of Waste") was passed on June 7, 1972; it was amended four times (mainly in 1986). Its successor is the Recycling Management and Waste Act (in force since 1996). A waste management system was established in Germany ; much of the waste that was previously dumped is now recycled or incinerated . This creates highly toxic substances; these are so-called hazardous waste (colloquially "hazardous waste").
In Germany, landfill classes 0 to IV are differentiated.
For the final disposal of highly toxic (highly toxic), conventional and radioactive waste, the introduction of the waste into deep geological formations (approx. 300-1,000 m depth) has become the accepted method worldwide.
The final disposal is based on the multi-barrier system . It consists of various barriers, each of which has its share in the retention of the pollutants and which should ensure the isolation of the pollutants overall. The barriers are technical and natural. Technical barriers include, for example, waste packaging and shaft closures. Natural barriers are formed by the geological formations surrounding the repository with very low permeability for water (the effective containment mountain area). Failure of all barriers is considered unlikely.
The main problem with final disposal lies in the possible slow transport of the finally deposited pollutants with the groundwater by advection and / or diffusion from the repository in the direction of the biosphere . In order to keep the transport of pollutants back into the biosphere as small as possible, even in the event of water penetrating the repository, attempts are being made to optimally coordinate the various barriers. However, safety considerations show that a slow release of pollutants with the groundwater from the repository cannot be ruled out with certainty over very long periods of time. The consequences of radiolysis in rock salt have so far been largely unexplored . Planned large-scale tests with highly radioactive nuclear waste, which were planned in the Asse II mine, were canceled in 1992.
Disposal of radioactive waste
So far there is no repository in Switzerland. All radioactive waste is temporarily stored. The total of nine siting regions for the possible final disposal of high-level and low-level to medium-level radioactive waste are concentrated in six areas and partially overlap.
Disposal of solid conventional waste
The same requirements can be made of the safety of a repository for particularly harmful conventional waste as for nuclear repositories. Their danger does not decrease because they are not subject to radioactive decay.
There are four locations in Germany where there are ways to safely lock conventional waste away from the biosphere in the long term :
- Herfa-Neurode (Hessen) with the UTD Herfa-Neurode ,
- Heilbronn (Baden-Württemberg) - Southwest German salt works ,
- Zielitz potash plant (Saxony-Anhalt),
- Sondershausen underground landfill in the disused Glückauf Sondershausen potash plant , Thuringia.
The following types of waste can be brought in:
- waste containing arsenic , cyanide or mercury
- Filter dust from the flue gas cleaning of household and hazardous waste incineration ( containing dioxin )
- PCB- containing transformers and capacitors
- Waste from the chemical industry
- solidified metal hydride slurries
The annual capacity of these storage facilities is several hundred thousand tons, the amount of toxic waste stored up to now has already exceeded the amount of 2.5 million tons.
Final storage of carbon dioxide
In addition to the final storage of radioactive waste, the storage or storage of carbon dioxide , usually called carbon dioxide , is increasingly being discussed. To what extent the previous concepts can be described as final disposal is still scientifically uncertain. In the course of efforts to protect the climate and to reduce CO 2 emissions when burning coal, the possibility of permanent storage of carbon dioxide is being investigated. Mine caverns or artificial caverns in salt domes do not have sufficient capacity for this. The space in exploited gas deposits also appears to be too small in Germany. In the case of electricity generation from coal, in addition to the range problem on the supply side, there is also a problem on the disposal side. The drawn also consider permanent storage or sequestration in deep aquifers seems to include environmental issues and is in conflict with other uses of the aquifer ( "aquifers"), for example to generate electricity from geothermal energy . Storage in seas or oceans, in the water column or in the sea floor is still a subject of research; storage in the water column is currently prohibited (see: London Convention of 1972 and OSPAR Agreement ).
There are some larger natural CO 2 deposits in the deep sea , usually close to hydrothermal fields , which, depending on the prevailing pressure (depth) and temperature conditions, create large carbon dioxide lakes (liquid CO 2 ) or deposits (CO 2 hydrate or " CO₂ ice ") form.
- Klaus-Jürgen Röhlig, Horst Geckeis, Kurt Mengel: Disposal of radioactive waste. Part 1: Facts and Concepts . In: Chemistry in our time 46 (3), pp. 140-149 (2012),
- Klaus-Jürgen Röhlig, Horst Geckeis, Kurt Mengel: Disposal of radioactive waste. Part 2: The host rocks: mudstone, granite, rock salt . In: Chemistry in our time 46 (4), pp. 208-217 (2012),
- Achim Brunnengräber (Ed.). Problem trap repository. Social challenges in dealing with nuclear waste , Baden-Baden 2016 ISBN 978-3-8487-3510-5 .
- Eberhard Wein: Underground landfill in Heilbronn: Toxic waste instead of salt - until at least 2028. In: stuttgarter-nachrichten.de. March 3, 2017, accessed June 12, 2020 .
- London Convention and Protocol ( Memento of April 18, 2009 in the Internet Archive ), International Maritime Organization .
- A lake of liquid carbon dioxide at a depth of 1,300 meters. Report from the Max Planck Institute for Marine Microbiology .