Glossar

 

FAQ

  • General background and legal framework
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      • Who is Nagra and what are its responsibilities?

        The Swiss Nuclear Energy Act embodies the polluter pays principle. The Swiss radioactive waste producers set up Nagra in 1972 to fulfil the task of developing and implementing safe and sustainable solutions for waste management. The members of the Nagra cooperative are the operators of the nuclear power plants, the Zwilag interim storage facility and the Swiss Confederation; the latter is responsible for waste arising from medicine, industry and research.

        The work involved in preparing the scientific and technical basis for the safe, long-term management of radioactive waste is documented in a waste management programme that has to be updated every five years. The Federal Government approved the waste management programme in August 2013.

        Within the framework set by the legislation, Nagra’s task includes planning, constructing and operating deep geological repositories in Switzerland. This also includes the search for suitable repository sites in accordance with the procedure set out in the “Sectoral Plan for Deep Geological Repositories”, which is under the lead of the Swiss Federal Office of Energy (SFOE). Nagra prepares siting proposals that are reviewed by the responsible authorities and commissions and then subject to a broad consultation procedure before the Federal Government makes a decision. Nagra is also responsible for submitting the applications for the general licences for the repositories.

      • Who supervises Nagra’s activities?

        The siting investigations and the later construction and operation of the deep geological repositories are supervised by the Swiss Federal Nuclear Safety Inspectorate (ENSI). ENSI is an organ of the Federal Government established under public law (Federal Act of 22nd June 2007). It assumed its activities as successor to HSK on 1st January 2009.

        The Federal Council and the licensing authorities can also call on the following expert groups and commissions to support them in their activities: the Swiss Federal Workgroup for Nuclear Waste Disposal (AGNEB), the Expert Group on Nuclear Waste Disposal (KNE) and the Nuclear Safety Commission (NSC). These bodies advise the Federal Council and its authorities on issues relating to safety.

        Foreign experts appointed by international organisations such as the Nuclear Energy Agency (NEA) also review key reports and concepts.

      • The Nuclear Energy Act that entered into force in 2005 calls for the waste producers to prepare a waste management programme. Was the work prior to this carried out without such a programme?

        Nagra’s work prior to the Act was based on a long-term waste management programme formulated by the waste producers, which was updated periodically (on average every five years). The Nuclear Energy Act, which entered into force on 1st February 2005, now calls for the waste management programme to be reviewed by the federal authorities and approved by the Federal Council. The Nuclear Energy Ordinance, which implements the terms of the Act, defines the content of the waste management programme as follows:

        • Origin, type and volumes of radioactive waste
        • Required deep geological repositories and concepts for their design
        • Allocation of the waste to the geological repositories
        • Implementation time plan
        • Duration and required capacity of centralised and decentralised interim storage facilities
        • Plan for financing waste management activities up to the time of the shutdown of the nuclear power plants
        • Information concept

        Nagra submitted the required waste management programme to the federal authorities in autumn 2008 and it was approved by the Federal Council in August 2013. A condition attached to the approval was that, in the future, Nagra should submit a research programme together with the waste management programme. The two programmes have to be submitted to the federal authorities together with the next cost study in 2016.

      • What is regulated by the Sectoral Plan for Deep Geological Repositories?

        The Federal Act on Spatial Planning states in Article 13 that the Federal Government has to establish the background that will allow it to fulfil its responsibilities that impact on spatial planning. It has to prepare the required sectoral strategies and sectoral plans and coordinate these with one another. The Nuclear Energy Ordinance calls for the objectives and requirements relating to deep geological disposal to be set out in a federal sectoral plan.

        The aim of the Sectoral Plan for Deep Geological Repositories is to identify sites for repositories in Switzerland. It defines the procedural steps and criteria for open and transparent site selection and regulates regional participation (participation of a siting region and its inhabitants) in the process. Safety has the highest priority when selecting sites, but socio-economic and spatial planning aspects also play an important role.  Following a broad consultation phase, the conceptual part of the Sectoral Plan was approved by the Federal Council on 2nd April 2008.

        The three-stage site selection process will lead to identification of one site each for a high-level waste (HLW) repository and for a low- and intermediate-level waste (L/ILW) repository. As an alternative, there is also the possibility for a combined repository for both waste types at the same site.

        In the first stage (2008 – 2011), six potential geological siting regions were identified as being suitable for repository construction based on safety criteria. The potential siting regions for a HLW repository are Zürich Nordost, Nördlich Lägern and Jura Ost. For the L/ILW repository, the regions are Südranden, Zürich Nordost, Nördlich Lägern, Jura Ost Jura-Südfuss and Wellenberg.

        The aim in the second stage is to concretise the repository projects in the potential siting regions and to compare the geological siting regions with one another. Again the most important criterion for decision-making is safety. At the end of stage two, at least two siting regions each will be selected for the L/ILW and HLW repositories. The SFOE also carries out cross-cantonal socio-economic-ecological impact studies for all the siting regions.

        In stage three, the remaining siting regions are investigated in more depth using 3D seismics and exploratory boreholes. The layout of the shaft head installations is also discussed and socio-economic and ecological impacts are further analysed. Nagra will make a provisional site selection around 2020 and will then prepare the general licence applications within around two years, i.e. the applications will be submitted around 2022. The final decision on the granting of the licences lies with the Federal Council and the Swiss voters. The Federal Council is expected to submit its decision to Parliament for approval around 2027; the decision is then subject to an optional national referendum.

      • What is the significance of the feasibility demonstration project (Entsorgungsnachweis)?

        The law requires the waste producers to demonstrate in a feasibility study that all radioactive waste can be disposed of safely on the long term in deep geological repositories. They also have to show that potential sites can be found in Switzerland where repositories can be constructed and operated in a way that fulfils the requirements of the authorities with respect to long-term safety.

        Nagra based its feasibility demonstration for spent fuel (SF), vitrified high-level waste (HLW) and long-lived intermediate-level waste (ILW) on the example of the Opalinus Clay in the Zürcher Weinland region. The reports documenting the project were submitted to the federal authorities in 2002 and, in June 2006, the Federal Council came to the overall conclusion that the feasibility of disposal had been demonstrated successfully for these wastes. This does not represent a siting decision - only a demonstration of the fundamental feasibility of constructing a geological repository in Switzerland as required by the Nuclear Energy Act. The feasibility demonstration serves as a basis for the Federal Council in deciding on future procedure in the waste management programme.

        The Federal Council approved the legally required feasibility demonstration for low- and intermediate-level waste disposal in 1988.

  • Deep geological disposal
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      • What is a deep geological repository?

        The Nuclear Energy Act calls for radioactive waste to be disposed of in deep geological repositories in Switzerland. A deep geological repository is a facility constructed at a depth of several hundred metres in a suitable rock formation. Depending on the type of waste to be disposed of, the repository consists of disposal tunnels or caverns, a pilot facility for monitoring a representative volume of the waste and a facility for underground geological investigations (FUGI). Surface infrastructure and access tunnel or shafts (or a combination of the two) are also required. During the construction and operation phases, additional installations are required at the surface, for example for storing excavated materials or for removing them from the site.

        A system of multiple engineered safety barriers is used to isolate the waste. These include, for example, suitable packaging of the waste (disposal containers) and backfilling of the disposal tunnels. The repository and its accesses have to be backfilled and sealed after the end of operations. After this, the long-term protection of man and the environment has to be assured passively by the safety barrier system. Closure of the repository can be a stepwise process, with periodic monitoring phases.

      • The sectoral plan states that, when selecting sites, safety has the highest priority. What does this mean?

        Safety, namely the long-term protection of man and the environment, has the highest priority in the disposal of radioactive waste. Safe isolation of the waste has to be assured until such time as the radioactivity has decayed to levels that are not harmful. The feasibility of constructing repositories that meet this requirement in Switzerland was demonstrated in the feasibility studies for low- and intermediate-level waste (L/ILW) and for high-level waste (HLW).

        It is recognised worldwide that disposal of high-level and long-lived intermediate-level waste in geologically stable formations ensures safety over the required long time periods. This principle is anchored in the Nuclear Energy Act and also applies in Switzerland to low- and intermediate-level waste. The repositories are engineered facilities, typically at a depth of several hundred metres underground. The host rock in which the repository is constructed (host rock) has to be stable on the long term, protected from erosion and sufficiently dimensioned to accommodate the expected volumes of waste. To ensure long-term isolation of the waste, the rock also has to be impermeable to water.  

        Criteria that are secondary to safety include aspects of land use planning, ecology, economics and politics. The influence of a repository on such criteria is analysed together with the affected siting regions as part of the Sectoral Plan process – for example the cross-cantonal socio-economic-ecological impact studies being carried out by the Swiss Federal Office of Energy (SFOE). To supplement these studies, the Cantonal Commission has also called for a study to investigate factors such as social cohesion and potential effects on the image of a region. 

      • What exactly are the safety barriers?

        In a deep geological repository, the waste is isolated from the human environment by an impermeable rock layer (the host rock or the natural safety barrier) and a series of staged engineered measures (engineered safety barriers). 

        The safety barriers can be explained using the following description of the emplacement of reprocessed high-level waste in a repository. The radioactive residues from reprocessing are mixed with molten glass (glass matrix) and the glass is poured into stainless steel canisters. These are then welded closed and placed in thick-walled steel disposal containers. These disposal containers are emplaced in repository tunnels excavated in the Opalinus Clay. Once the containers have been emplaced, the tunnels are backfilled with bentonite, a natural clay material. The engineered barriers consist of the glass matrix, the disposal container and the bentonite backfill and the Opalinus Clay host rock represents the natural barrier. The task of the engineered barriers is to contain the waste until such time as most of it has decayed to an acceptable level. The geological barrier represented by the host rock also retains radioactive substances. Together with other (mainly overlying) rock formations termed confining units, the host rock protects the engineered barriers from environmental influences such as erosion and water influx. 

      • Have other countries already constructed geological repositories?

        In some countries (e.g. Sweden and Finland), geological repositories for low- and intermediate-level waste have already been in operation for some time. In other cases, low-level waste has also been disposed of in near-surface facilities (e.g. in the USA, Canada, France and the UK).

        Worldwide, there is as yet no operational geological repository for high-level waste. The waste has to be left to cool for several decades before it can be placed in a repository. In Finland, work on a geological repository is already underway with construction of a rock laboratory; construction of the actual repository will begin in several years. Planning of facilities is also fairly advanced in Sweden and France. In the USA, a deep geological repository for long-lived intermediate-level military waste (so-called transuranic waste) is already in operation.  

      • How are sites selected in Switzerland?

        Site selection for deep geological repositories is conducted within the framework of the Sectoral Plan for Deep Geological Repositories, as specified by the Nuclear Energy Ordinance and the Spatial Planning Act. The process is led by the Federal Government and aims to identify sites for geological repositories using a broadly based, transparent approach. Safety has the highest priority in the search for sites, but socio-economic and spatial planning aspects also play an important role.

        The search is for sites that fulfil all the protection objectives specified by the regulatory authorities and for which implementation would be reasonable from a spatial planning perspective. The Sectoral Plan approach allows all the spatial planning implications of constructing repositories to be fully coordinated and ensures early involvement of the affected Cantons, local communities and the authorities of neighbouring countries, as well as the public and interested organisations. 

      • What economic and social impacts will a geological repository have on a potential siting region?

        The most important aspect of a deep geological repository is the long-term safety of man and the environment and this is at the forefront of all discussions. Risks to health must be ruled out. However, economic and social impacts are also important factors for a potential siting region. Information has to be provided on all possible impacts before, during and after the operation of the repository.

        The Swiss Federal Office of Energy (SFOE) is carrying out cross-cantonal socio-economic-ecological impact studies for all the potential siting regions in stage two of the Sectoral Plan process. These provide information on economic, ecological and social aspects to be considered when comparing the sites in stage two. A supplementary study called for by the Cantonal Commission is looking at image effects and the social implications (for example social cohesion) of site selection. A report synthesising the results of the two studies will provide an important basis for the opinions to be submitted by the regions and the Cantons on the results of stage two and will be taken into consideration in the overall assessment made by the Federal Council at the end of stage two.

        The studies allow the affected regions to recognise any negative effects that may from the presence of a repository and to counteract these as early as possible using strategies for regional development. If this is not possible, the studies at least provide a sound database for working out possible compensation payments.

        An interim report documenting the initial results of the socio-economic-ecological impact studies has shown that the economic changes brought about in a region by the construction of a repository are small. Considered over the time period from construction of the facility for underground geological investigations to closure of the repository (the entire lifecycle), both the positive and negative impacts amount to considerably less than 1% of current regional added value, employment or tax income.

        A study conducted in the Zürcher Weinland region in September 2005 came to the conclusion that the image of the region could suffer in terms of its sales of agricultural products. However, systematic inquiries made at the sites of interim storage facilities and repositories in Switzerland and other countries have not confirmed these fears.

      • Is it possible to retrieve waste from a repository?

        The law requires that the possibility of retrieving the waste must exist. If a decision is made to retrieve waste during emplacement operations or during the monitoring phase prior to closure of the repository, this will be possible with relatively little effort. Once the repository has been backfilled and closed, however, the effort required will be correspondingly greater as both the backfilled emplacement tunnels and accesses to the tunnels would have to be re-opened. However, retrieval still remains technically possible. It would be conceivable if future generations wished to use the radioactive waste as a resource or decide on an alternative disposal solution.

      • How can radioactive waste be disposed of safely on the long term?

        Spent uranium fuel reaches radiotoxicity levels comparable with natural rock formations at the earth’s surface after around 200,000 years. Until such time as this non-hazardous level has been reached, the highly active waste has to remain safely isolated from the human environment [source: http://www.nagra.ch/en/longtermsafety.htm].

        World history has shown that social structures cannot be relied on to remain stable over long timescales. Even just the last hundred years of European history show this clearly. On the other hand, the history of the earth shows us that – compared to social structures – rock formations can remain stable over many millions of years and their properties remain effectively unchanged. It could be said that time stands still underground, irrespective of what is happening at the surface. If the rock strata are also impermeable, they are capable of confining substances over geological timescales. Compared to such timescales, the required containment time for high-level waste of around 200,000 years is relatively short. 

        Facilities at the surface that rely on maintenance and supervision over generations to ensure their safety are only interim storage facilities. The Nuclear Energy Act calls for deep geological disposal for the long-term management of all categories of waste. This aim is to ensure passively safe, long-term isolation of the waste without any human intervention. It is agreed internationally that a sealed geological repository provides optimum long-term safety. 

        Containment for around 200,000 years can be assured by emplacing the waste in a repository at a depth of several hundred metres in a very low permeability host rock – for example the Opalinus Clay. The Opalinus Clay is around 175 million years old and was formed from clay particles that were deposited on the sea floor. The shells of ammonites living in the sea at that time were embedded in the clay and have been preserved as fossils from the time when the rock was formed until today. The required containment time for radioactive waste is only around 1/1000 of the age of the Opalinus Clay. The clay has a very low permeability and the porewater is practically immobile. The water in the fine pores still contains a component of seawater that was confined when the clay was formed some 175 million years ago. 

      • How can future generations be prevented from inadvertently drilling or mining into the repository?

        A deep geological repository has to be constructed in such a way that the long-term safety of the human environment can be assured even if the existence of the repository is forgotten sometime in the future.

        A series of measures can be used to protect a repository from unintentional intrusion, for example avoiding areas with potentially exploitable deposits of raw materials (e.g. coal, ore, geothermal) wherever possible in the siting process. Locating the facility at a depth of several hundred metres is also important as the repository would be reachable only with highly sophisticated drilling or tunnelling technology. If our descendants are in the position in the distant future to drill to depths of several hundred metres, they should also be capable of detecting the presence of radioactivity and taking the necessary precautionary measures.

        The Nuclear Energy Act also calls for the permanent marking of geological repositories. When submitting the application for a repository construction licence, Nagra has to include a concept for its permanent marking and preservation of knowledge. Suitable concepts have long been the subject of discussion in international forums, also with the participation of Switzerland. As a knowledge preservation measure, the Federal Government also archives the data on the repository on the long term.

      • In Switzerland, why is waste not simply disposed of in disused military installations?

        The locations of the tunnels and caverns of former military fortifications were selected on the basis of strategic considerations. Criteria such as low permeability of the rock or long-term protection from erosion played no role in the selection. The sites of these installations are often near the surface in weathered, permeable rock and long-term safe containment of the waste is not possible under such conditions. In no way do military installations meet the strict requirements that apply today to host rocks and sites for geological repositories.

      • Do earthquakes pose a risk for geological repositories?

        For the last 20 years, a network of stations operated by the Swiss Seismological Service and Nagra in Northern Switzerland has been measuring all the earthquakes in the region, even very weak ones which cannot be sensed by humans or animals. An understanding of the earthquake situation in a region is important for evaluating the long-term safety of a repository. Earthquakes are triggered by movements in the earth’s crust. An analysis of seismic data allows active fault zones to be located underground; these are to be avoided when siting the repository. 

        Worldwide investigations in shafts, tunnels and caverns in earthquake regions show that damage to underground structures is rare and decreases rapidly with depth. Geological repositories at a depth of several hundred metres located at a safe distance from fault zones will therefore not be at risk even from strong earthquakes. 

  • Production and interim storage of radioactive waste
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      • What is the energy content of uranium compared to fossil fuels?

        Uranium has a very high energy density, in other words a very high energy content. One kilogramme of uranium provides the same energy as 120,000 kilogrammes of heating oil or 140,000 kilogrammes of coal. This amount of energy would be sufficient to heat an average family home for around 60 years.

      • Where is radioactive waste produced and what categories of waste are there?

        Around two-thirds of the radioactive waste comes from the nuclear power plants. The power plants are the main producers of waste particularly in terms of radiotoxicity. The waste arises in the fuel during the operation and later dismantling of the plants. One-third of the waste arises from a wide range of applications of radioactive materials in the areas of medicine, industry and research. Nagra maintains a model inventory of all radioactive waste.

        In line with Article 51 of the Nuclear Energy Ordinance, the waste is divided into the following categories based on its physical properties and disposal pathway:

        • High-level waste (HLW): vitrified fission products from reprocessing and spent fuel assemblies for direct disposal
        • Alpha-toxic waste (ATW): waste containing alpha emitters exceeding a value of 20,000 alpha decays per second and gram of conditioned waste. This waste comes mainly from the reprocessing of spent fuel
        • Low- and intermediate-level waste (L/ILW): all other radioactive waste

      • What is involved in reprocessing of spent fuel?

        Fuel assemblies have to be exchanged after four to five years in the reactor of a nuclear power plant because the content of fissile uranium becomes too low.

        Spent nuclear fuel is a mixture of around 95% uranium (with around 1% fissile uranium-235), 4% highly active fission products, and 1% plutonium.  

        Spent fuel has to be managed as high-level waste but there is the possibility for recycling. The fissile material (uranium, plutonium) still contained in the fuel assemblies can be separated from the fission products (no longer usable) in a reprocessing plant and used to manufacture new fuel assemblies. The fission products are treated as high-level waste and immobilised in a glass matrix. 

        Up to 2006, around 1100 tonnes of spent fuel from the five existing Swiss power plants had been sent abroad (France/England) for reprocessing. The separated waste has to be returned to Switzerland and this will be complete by the end of 2018. Since July 2006, the Nuclear Energy Act has prohibited the export of spent fuel for reprocessing (moratorium); this will continue until 2016.

      • Where is the radioactive waste today?

        Spent fuel assemblies are currently stored at the power plant sites and in special storage casks at the Zwilag interim storage facility. After removal from the reactor, the fuel is stored in storage pools at the power plants for five to ten years to allow cooling. It is then packaged into transport and storage casks and transferred to the Zwilag centralised interim storage facility in Würenlingen. The power plants also have further storage capacity. Prior to the 10-year moratorium on exporting spent fuel for reprocessing (since July 2006), some of the spent fuel was sent abroad for reprocessing. The waste arising from this process is currently being transported back to Switzerland; this will be completed by the end of 2018.

        Low- and intermediate-level waste from the nuclear power plants is processed into a form suitable for disposal either at the power plant sites or in Zwilag in Würenlingen, packaged into suitable containers and then stored either at the power plant sites or at Zwilag. Raw waste from medicine, industry and research is packaged into a form suitable for disposal at the Paul Scherrer Institute or at Zwilag and then stored in the Federal Government's own interim storage facility in Würenlingen. 

        Nagra maintains a centralised inventory of all radioactive waste. There is sufficient interim storage capacity for all waste arising from the operation and decommissioning of the four nuclear power plants (total of five reactors) until such time as the geological repositories become available. At the end of 2013, for example, 40 containers with high-level waste from reprocessing or spent fuel assemblies were stored at Zwilag. This corresponds to around 20% of the capacity of the storage hall. 

      • What volumes of radioactive waste can be expected in Switzerland?

        For an operating lifetime of 50 years for all the Swiss power plants, the operators expect around 3600 tonnes of spent fuel. Packaged in disposal containers, and taking into account partial reprocessing, this would amount to 7325 cubic metres of waste, which roughly corresponds to the volume of seven single-family homes.

        For a 50-year operating lifetime of the five existing power plants, Nagra expects a total of around 60,000 cubic metres of low- and intermediate-level waste (including disposal containers). Around half of this is waste arising from the dismantling of the power plants. An additional 33,000 cubic metres of low- and intermediate-level waste will arise from applications in the areas of medicine, industry and research. 

        The total volume of radioactive waste for disposal thus amounts to around 100,000 cubic metres (including disposal containers). 

      • How large are the volumes of radioactive waste compared to other wastes?

        In Switzerland, around 5000 tonnes of radioactive waste, including packaging, arise every year (on average, calculated over 50 years). The waste from decommissioning of the nuclear power plants, which will only arise later, has already been factored into this amount. The waste has to be isolated from the human environment for as long as it remains toxic, but toxicity decreases with time due to radioactive decay.

        By way of comparison, more than 2.2 million tonnes of special wastes are produced annually [source: statistics on special wastes for 2012, Federal Office of the Environment]. This includes, for example, acids and leachates, solvents, oils, fly-ash and filter dust, lead batteries, road collection slurries and soil contaminated with mineral oil products or other substances (legacy wastes). A large component of these special wastes can be reduced in terms of weight (e.g. incinerated) or detoxified (e.g. neutralisation of acids). Somewhat more than one quarter (i.e. around 550,000 tonnes) has to be isolated from the environment for all time. This is carried out in around 50 surface disposal sites in Switzerland and in underground facilities abroad (e.g. decommissioned salt mines). 

  • Financing waste management
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      • Who pays for the management of radioactive waste?

        Financing the management and disposal of radioactive waste and spent fuel assemblies from the nuclear power plants is regulated by the Nuclear Energy Act. The waste producers are obliged by the polluter pays principle to dispose of the waste safely at their own cost. The waste management costs arising today (e.g. for reprocessing, Nagra's investigations, construction of interim storage facilities) are met by the producers on an ongoing basis. Decommissioning costs and waste disposal costs arising after the shutdown of the power plants have to be covered at the time of shutdown and an amount of around one Rappen (100 Rappen = 1 Swiss Franc) per kilowatt hour is included in the price of nuclear electricity to cover these costs. This money is paid into two funds – the decommissioning fund and the waste disposal fund. These funds are controlled by the authorities and no taxpayers’ money is used for this purpose. The details of financing are regulated by the 2007 Ordinance on the Decommissioning and Waste Disposal Funds for Nuclear Installations.

        The funds are developing according to plan and the accumulated assets at the end of 2013 amounted to around 5.3 billion Swiss Francs [source: www.bfe.admin.ch]. Current information on the funds can be found on the websites www.entsorgungsfonds.ch and www.stilllegungsfonds.ch (partly available in English). 

        During the operating lifetime of the nuclear power plants, the costs of waste management are paid by the plant operators on an ongoing basis. By the year 2025, these are expected to amount to around 7.5 billion Swiss Francs. Cost studies have shown that the decommissioning and waste disposal costs of around 11.4 billion Swiss Francs expected in addition to this will be covered by the two funds [source: 2011 cost study of swissnuclear]. 

        The Federal Government is responsible for disposing of waste from medicine, industry and research, for which it currently operates an interim storage facility in Würenlingen. The producers of this waste pay a volume-dependent fee to the Federal Government for disposal. The Government also contributes around 3% to Nagra's costs.  

  • Waste and radiation
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      • What is radioactivity?

        Radioactivity is produced by the spontaneous transformation of an atomic nucleus, which causes small fragments to separate off or electromagnetic radiation to be emitted. There are two main types of nuclear transformation – alpha and beta decay - which produce alpha, beta and gamma radiation. After transformation, the nucleus is stable (no longer radioactive) or it decays in further steps until it reaches a stable form.

        Natural radioactive substances are present everywhere. New natural and artificial radioactive substances are produced on earth by high-energy radiation from space, in particle accelerators and in nuclear reactors. Each chemical element has different types of atoms (isotopes) that differ only in terms of the number of neutrons (neutral atomic particles). Many isotopes are radioactive. For example, the element caesium has 40 radioactive isotopes and only one stable isotope. The time taken for half of the nuclei of a radioactive isotope to decay is called the half-life and varies from isotope to isotope. It can range from fractions of a second to billions of years. 

      • What protection is there from radiation?

        Protection from radiation can be achieved by restricting the time period of exposure, by increasing the distance from the radiation source and by suitable shielding. Reliable monitoring is possible because radiation is easy to measure.

        Radioactive substances should not enter the body in unacceptable concentrations via inhalation or ingestion because the effect of radiation is much greater inside the body than it is externally. The uptake of radioactive substances into the body is termed incorporation.

        However, uptake can never be completely prevented as naturally radioactive substances are present in air, drinking water and foodstuffs. 

      • How much radiation will reach the earth's surface from a deep geological repository?

        No direct radiation can reach the earth's surface from a deep geological repository because the radiation is completely absorbed by just a few metres of rock.

        The purpose of a geological repository is to effectively isolate radioactive waste and prevent it from being released and contaminating the human environment. The engineered safety barriers prevent or delay the release and transport of radioactive substances into the surrounding rock. The welded thick-walled steel disposal container foreseen for high-level waste ensures complete containment of the waste for at least 10,000 years in a clay disposal medium.

        A repository has to ensure the permanent protection of man and the environment. The safety authorities have specified objectives that quantify the required level of protection: at no time shall the release of radionuclides from a sealed repository give rise to individual doses that exceed 0.1 millisieverts per year [source: ENSI Guideline G03]. Nagra has been able to show by means of safety analyses that these protection objectives can be met thanks to the planned multiple safety barrier system. All calculated dose values are significantly below the protection objective of 0.1 millisieverts per year.

        Radiation from natural and artificial sources continuously affects our bodies and leads to an average dose rate in Switzerland of 5.5 millisieverts per year. The majority of this (around 60%) comes from radon and its decay products. These are present in the air in our living spaces and contribute an average of 3.2 millisieverts per year to the natural radiation dose. There are regional variations as natural radiation depends on the soil and the rock. Artificial radiation of an average of 1.2 millisieverts per year comes mainly from medical applications. Common examples of this include treatment of the thyroid with radioactive iodine-131 and positron emission tomography (PET) in diagnosing cancer. The latter imaging technique involves administering radioactive tracers to the patient. Doses due to medical applications also vary significantly: around two-thirds of the population receive practically no dose, while a few percent are exposed to more than 10 millisieverts.

      • How long does radioactive waste remain radioactive?

        Radioactive waste contains a mixture of different types of radioactive atoms (radionuclides). The composition of the waste is known and the decrease in radioactivity with time can therefore be calculated for the different waste types. It is true for all waste types that toxicity decreases as a result of radioactive decay and, after a certain time, the waste will have an activity that is comparable with that of natural substances. However, the time required for this varies very widely for the different waste types.

        In general, it can be said that low- and intermediate-level waste reaches a radiotoxicity equivalent to that of granite after around 30,000 years. The radioactivity of spent uranium fuel reaches the radiotoxicity of the uranium ore once mined to produce it after around 200,000 years. 

      • Will geological repositories once day become superfluous thanks to transmutation technology?

        Transmutation generally means the transformation of nuclides by nuclear reactions. Transmutation of radionuclides is understood to mean deliberate transformation into radionuclides with shorter half-lives. The radiotoxicity of the waste thus decreases more quickly. Transmutation is initiated by bombarding the material to be transformed with neutrons or protons, which triggers various nuclear processes and results in new atomic nuclei.

        Transmutation is repeatedly advocated as a means of transforming long-lived radionuclides into shorter-lived nuclides. This is theoretically possible, but cannot be implemented in practice on a large scale using current technology. The processes involved are presently the subject of extensive research, with the ultimate aim of being able to transform long-lived radioactive wastes into shorter-lived wastes in the future. Even if transmutation technology becomes practicable, geological repositories will still be required for the resulting shorter-lived wastes and for low- and intermediate-level waste that is not suitable for transmutation. 

  • Disposal of spent fuel (SF), high-level waste (HLW) and long-lived intermediate-level waste (ILW)
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      • Where will the deep geological repository for high-level waste be constructed?

        From a geological perspective, there are several different host rocks and areas in Switzerland which - together with a suitable engineered barrier system - would allow construction of a safe geological repository. Based on the results of extensive investigations, Nagra was able to demonstrate in 2002 that deep geological disposal of high-level waste (HLW) is feasible in Switzerland. The Federal Council approved this feasibility demonstration in 2006. However, this did not represent a siting decision and the search for suitable sites was then initiated.

        The Federal Government initiated the Sectoral Plan for Deep Geological Repositories in 2008. The site selection process is carried out in three stages under the lead of the federal authorities. The aim of the process is to identify one site each for a high-level waste repository and a low- and intermediate-level waste repository (or one site for a combined repository).

        In the first stage (2008 – 2011), three potential geological siting regions were identified as being suitable from a safety viewpoint for the construction of a HLW repository: Zürich Nordost, Nördlich Lägern and Jura Ost.  The following safety-relevant aspects were considered: long-term geotectonic stability and a suitable host rock with the required depth, thickness and extent. The Opalinus Clay, which is around 175 million years old, has been identified as a suitable host rock for disposal of high-level waste.

        The aim in the second stage is to concretise the repository projects in the potential siting regions and to compare the regions with one another. Again the most important decision-making criterion is safety. At the end of stage two, at least two siting regions will be selected for the HLW repository.

        In stage three the remaining siting regions are investigated in more depth using 3D seismics and exploratory boreholes. Nagra will make its provisional site selection around 2020 and will prepare the general licence application within around two years. The application will be submitted to the authorities around 2022. The final decision on the granting of the licence lies with the Federal Council and the Swiss voters. The Federal Council is expected to submit its decision to Parliament for approval around 2027 and the decision is then subject to an optional national referendum.

      • What is Opalinus Clay?

        Some 175 million years ago, large areas of what is today the European continent were covered by a sea. In the Strasbourg-Stuttgart-Zürich-Bern region, clay particles were deposited on the sea floor and, over the course of geological time, they solidified to form a clay layer (Opalinus Clay). The formation shows similar properties over a large area. It has a very low permeability and provides a stable geochemical environment that is suitable for retaining radioactive substances and for the long-term functioning of the engineered barriers. Its mechanical properties are also suitable for the construction of a deep geological repository. 

      • How much space will be required for a high-level waste repository?

        Various operational buildings making up the surface facility will be located at the earth's surface. These will be equivalent to an average-size industrial plant and will be integrated as far as possible into the landscape. The area required for the surface facility of the repository will depend on the site-specific boundary conditions and the later detailed layout of the facility. Based on current planning, the area will be around eight hectares, with a width of around 150 metres (guideline values). Around 2.5 hectares will be required for various structures and buildings [source: Nagra Technical Report NTB 11-01].

        The surface facility is connected to the underground repository by an access structure (shaft or ramp or a combination of the two). The repository will also have a vertical shaft.

        Spent fuel assemblies and long-lived intermediate level waste will be emplaced in the high-level waste repository. The underground installations will include emplacement tunnels for high-level waste, disposal drifts for long-lived intermediate-level waste, the associated infrastructure, a facility for underground geological investigations (FUGI) and a pilot facility. The latter will contain a small representative volume of the emplaced high-level waste and will be used to monitor the behaviour of the repository. The minimum space required underground for the repository is around four square kilometres, with a width of 1500 metres [source: Nagra Technical Report NTB 08-05].

  • Disposal of low- and intermediate-level waste (L/ILW)
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      • Where will the deep geological repository for low- and intermediate-level waste be constructed?

        From a geological perspective, there are several different host rocks and areas in Switzerland which - together with a suitable engineered barrier system - would allow construction of a safe geological repository. Based on extensive investigations conducted as part of the Project Gewähr 1985 study, Nagra was able to demonstrate that deep geological disposal of low- and intermediate-level waste (L/ILW) is feasible in Switzerland. The Federal Council approved this feasibility demonstration in 1988. This did not, however, represent a siting decision and the search for suitable sites was then initiated.

        With the Sectoral Plan for Deep Geological Repositories, the federal authorities defined a new approach to the site selection process in 2008. Sites are selected in three stages under the lead of the federal authorities. The aim of the process is to identify one site each for a high-level waste repository and a low- and intermediate-level waste repository (or one site for a combined repository).

        In the first stage (2008 – 2011), six potential geological siting regions were identified as being suitable from a safety viewpoint for the construction of a HLW repository: Südranden, Zürich Nordost, Nördlich Lägern, Jura Ost, Jura-Südfuss and Wellenberg. The following safety-relevant aspects were considered: long-term geotectonic stability and a suitable host rock with the required depth, thickness and extent. The Opalinus Clay, which is around 175 million years old, and other clay-rich sediments (Brauner Dogger, Effingen Member, Helvetic marl formations) are considered as suitable host rocks for a low- and intermediate-level waste repository.

        The aim in the second stage is to concretise the repository projects in the potential siting regions and to compare the regions with one another. Again the most important criterion for decision-making is safety. At the end of stage two, at least two siting regions will be selected for the L/ILW repository.

        In stage three the remaining siting regions are investigated in more depth using 3D seismics and exploratory boreholes. Nagra will make its provisional site selection around 2020 and will prepare the general licence application within around two years. The application will be submitted around 2022. The final decision on the granting of the licence lies with the Federal Council and the Swiss voters. The Federal Council is expected to submit its decision to Parliament for approval around 2027 and the decision is then subject to an optional national referendum.

      • How much space will be required for a low- and intermediate-level waste repository?

        Various operational buildings making up the surface facility will be located at the earth's surface. These will be equivalent to an average-size industrial facility and will be integrated as far as possible into the landscape. Based on current planning, the area required for the surface facility will be around five hectares, with a width of around 130 metres (guideline values). Around 2.5 hectares will be required for the various structures and buildings [source: Nagra Technical Report NTB 11-01].

        The surface facility is connected to the underground repository by an access structure (shaft or ramp or a combination of the two). The repository will also have a vertical shaft.

        Concrete disposal containers filled with waste drums will be emplaced in the repository. The underground installations include disposal caverns for the low- and intermediate-level waste, the associated infrastructure, a facility for underground geological investigations (FUGI) and a pilot facility. The latter will contain a small representative volume of the emplaced waste and will be used to monitor the behaviour of the repository. The minimum space required underground for the repository is around two square kilometres, with a width of 1000 metres [source: Nagra Technical Report NTB 08-05].