Linguistic editing: Sylvie Peter

Atom for Peace

In his book on the building of the Tower of Babel (“Der Turmbau zu Babel”), Friedrich Dürrenmatt, a famous Swiss writer, describes a library, which once contained the memory of every single person that lived on planet Earth (Dürrenmatt 1991). The miscellaneous information contained in the book was an overwhelming array of facts and movements, emotions and sensations of the history of mankind. It provided a thorough, but useless accumulation of information and was finally abandoned, since it was regarded as a totally messy archive that barely explained the real development of mankind.

The brief historical account of the early development of nuclear power in Switzerland is also based on a vast plethora of facts, a huge amount of interesting information and even some remarkable data on human, social and factual issues that accumulated over the past few decades. These may be of interest to specialists, such as Dürrenmatt’s universal library, the “history of details”. The main findings and general trends therefore had to be filtered out first. In fact, the key features and trends of development can only be perceived from a certain distance.

Therefore, our brief review does not include all the facts and developments in the long chain of events from the first debate on Swiss nuclear power to the management of radioactive waste. This account rather focuses on a few essential cornerstones to help the reader understand the general development of nuclear power in Switzerland.

At international level, military applications of nuclear fission, such as nuclear weapons, nuclear reactors, power submarines, and surface vessels were developed during World War II and in the years directly following the War. The military reactor technology was subsequently transferred and adapted to the civil sector; particularly the American industry with its uranium fuelled and water-cooled reactors rapidly gained a key commercial position. Yet, the Russian reactor of Obninsk was the first civilian reactor to initiate the commercial use of nuclear energy.

As a result of these developments, the so-called „peaceful use of nuclear power“ was hotly debated in industrialised nations in the late 50s of the 20th century. Initially, this debate had a rather theoretical character, with the two international conferences on „Atoms for Peace“ in 1955 and 1958 in Geneva. However, the attitude became more engaged in 1979 following the accident at the nuclear power plant of Three Mile Island (TMI) in the USA, which led to a partial melting of the reactor core. The key question of the debate centred in particular on the question of whether safe operation of nuclear reactors could ever be guaranteed. The security concepts and emergency equipment for nuclear power plants were thus significantly strengthened. In the US, the accident of TMI induced a period of a de facto moratorium regarding the approval of new nuclear power plants.

The reactor explosion at Chernobyl in 1986 resulted in a large number of deaths and radiation exposures, particularly among the so-called „liquidators“ of the reactor accident. This led to the evacuation of thousands of residents and caused radioactive fallout over vast areas of Europe. Although this disaster left deep scars in the collective consciousness, the consequences for the nuclear industry were relatively limited, as the accident reactor of Chernobyl was „only“ a graphite-moderated reactor of Russian design. The development of the EPR (European Pressurised Water Reactor), based on the classical reactor technology with increased security measures, can be regarded as one of the consequences of this accident. However, the evaluation of this reactor line also disclosed a rather sobering conclusion.

The situation after the destruction of four commercial nuclear reactors in Fukushima, Japan on 11 March 2011 is quite different. These reactors of American design suffered heavy damages during the earthquake and subsequent tsunami and ended in a nuclear meltdown. The population was evacuated quite rapidly and efficiently, so few lives were lost. However, large tracts of land were contaminated by radioactive fallout and are now uninhabitable. About 40 commercial nuclear reactors worldwide (of roughly 440 nuclear reactors totally) are comparable to the destroyed Japanese reactors, and over one hundred are similar in design. This gave rise to a risk awareness movement and to a rethinking of the future policy on nuclear power use, not only in Japan, but also in other parts of the world. Germany, for example, decided to drop its nuclear power programme and Switzerland will not replace its nuclear plants after their operational lifetime. This so-called „nuclear phase-out“ or abandoning of unprofitable production lines, certainly does not mean nuclear safety, but on-going risks and the need to protect the population from potential reactor accidents for another 20 to 30 years or much longer if the dangers emitted by nuclear waste are taken into consideration.

How Switzerland turned nuclear

In Switzerland, especially at the ETHZ (Swiss Federal Institute of Technology Zurich) and at the University of Basel, nuclear research was already conducted in the 1930s and during World War II. However, the bombings of Hiroshima and Nagasaki on 6 and 9 August 1945 triggered an earthquake throughout the academic world. Peter Hug (1987) writes in his monograph on the Swiss nuclear history (p.71): „A few days after the atomic bombing, the military use of nuclear energy was already discussed in Bern, the Swiss capital. The initiative was launched by two letters addressed to the head of the Swiss Federal Military Department (EMD, since 1998: Federal Department of Defence ). The first came from the head of training of the Swiss army, Corps Commander Hans Frick and was dated 15 August 1945; the second, dated 20 August 1945, came from Otto Zipfel, the delegate for job creation and an already well known promoter of nuclear technology.” As a result, the Federal government funded (officially in 1946) the „Study Commission for Atomic Energy“, largely dominated by the Swiss Federal Military Department, and nuclear research was transferred from civilian to military use. The military option of using nuclear power in Switzerland was only abandoned in the 1980s.

Figure 1: Schematic view of the Swiss experimental nuclear reactor of Lucens (https://www.ensi.ch/fr/topic/centrale-nucleaire-lucens/)

In 1953, Switzerland acquired for the first time a „significant“ amount of uranium ore (about 10 tons) from Belgium and the UK (according to the motto: “without uranium, nothing works“).

The history on the civilian use of nuclear power began in 1953, when Walter Boveri founded the company „Reactor AG“ with the aim to develop a Swiss nuclear reactor. This private company was created with capital from the machine and electricity industry, banking, insurance and finance companies and by a subsidy from the Swiss federal government. Reactor AG built the research reactor „Diorite“ in Würenlingen, which was surprisingly dropped by Walter Boveri and Paul Scherrer who purchased the American „Saphire“ research reactor. The commercially operated reactors performed randomly. In 1960, the Parliament approved a loan of CHF 50 million for the construction and operation of experimental research reactors. Subsequently, the Swiss industry funded the „National Association for the Advancement of Industrial Nuclear Technology“ (NGA) and started building a gas-cooled reactor operated with uranium. This reactor was installed in Lucens (western Switzerland) in rock caverns. It went into operation in 1968 and suffered a partial meltdown of the reactor core on 21 January 1969. In order to protect the environment and the population, the rock caverns were closed and sealed. This was the end of the story regarding the development of a Swiss reactor.

Meanwhile, Swiss electricity companies had already purchased reactors in the United States: In 1969 Beznau 1, the first nuclear power plant with a pressurised water reactor from Westinghouse was connected to the grid; a second reactor of the same type followed two years later and the nuclear power plant of Mühleberg, with a boiling water reactor from General Electric in 1972. In 1969, the project of the nuclear power plant Gösgen was launched; the Siemens pressurised water reactor was connected to the grid in 1979, followed in 1984, 12 years after the project began, by the nuclear power plant of Leibstadt, with a boiling water reactor from General Electric. Following the post Fukushima government decision in 2011 not to replace the aging nuclear power plants, the owner company BKW (Bernische Kraftwerke AG) has decided to shut down the Mühleberg reactor in 2019.

After a theoretical operational lifespan of 50 years, about 7 300 m³ of highly radioactive waste will have to be disposed of, in addition to 93 000 m³ of low and intermediate radioactive waste from nuclear power plants and 33 000 m³ of waste from medical, industrial and research sources.

From sea dumping of radioactive waste to the multi-barrier approach

Marie Sklodowska Curie was born on 7 November 1867 in Warsaw and died of cancer in the sanatorium of Sancellemoz at Passy (France) on 4 July 1934. It is widely known that the radioactive radiation, to which she had been exposed in the context of her experiments in the research laboratory, had triggered the deadly disease.

Figure 2: Marie Curie.

 Direct exposure to radioactive radiation was perceived quite early as a health hazard, both by scientists and the public. However, its real effects had long been underestimated. In 1913, the German author Ernst Weiss published a novel describing the life and agonizing death of a physicist who had been experimenting for years with radioactive sources. Yet, the general public underestimated for another two decades the dangers of radioactivity. Especially from the 1920s onwards, radium and radon have also been hailed for medical and wellness use, the first (radium) in cosmetics and medical applications, the second in health cures.

The death of the American businessman and golfer Eben Byers in the early 1930s finally led to a broader perception of the dangers of radioactive radiation. Byers had absorbed for years large amounts of the radium-containing drug Radithor. With the decease of Marie Curie two years after Byers’s death, the risk of radiation finally started to raise public concern. However, two more decades were necessary until the scope of the radiation problem was finally perceived, i.e. not until the nuclear bombs of Hiroshima and Nagasaki had revealed the impact of the new weapons and terrible effects of radioactivity. After the war, it took almost 20 years and hundreds of atmospheric nuclear tests until the West and East agreed to stop the spread of radioactivity on our planet. In August 1963, the Convention for the Comprehensive Nuclear Test Ban was drawn up.
That same year, the Swiss Radiation Protection Ordinance SSVO was enforced. In retrospect, the following public notice exemplifies the naivety of the people in charge:
„Anyone supplying radioactive waste to the sewer has to rinse with a copious amount of water.“

Figure 3: Nuclear waste management facility illustrated in the Swiss Federal Radiation Protection Ordinance 1963 (https://www.zeno.org/Meyers-1905/I/010061a).

“Rinse and dilute. . . .” In the late 1940s, scientists even considered dilution of the total radioactive inventory in the world’s oceans. Similar proposals were put forward in the 1950s at the international conferences of IAEA. Bioaccumulation was not considered in the “rinsing strategy”, whether intentionally or not: Water filtrating organisms (e.g. plankton in rivers and seas) accumulate metals and other pollutants in their bodies. The radioactive plankton absorbed by the fish then enters the human food chain.

With a view to dilute its radioactive substances, Switzerland started radioactive waste dumping in 1969. Since 1946, these disposal processes were already standard practice in the United States. They were initially used for liquid, high-level or other waste, packed in steel canisters or 200-litre containers. Solid waste, solidified with bitumen or cement, was „disposed of“ in the North Atlantic by the Swiss operators under the „supervision“ of the NEA (Nuclear Energy Agency of the OECD).

A number of these dumping sites have been used worldwide. In accordance with the recommendations of IAEA, the packaging had the purpose of protecting the waste during its descent in the sea and impact on the ground. Subsequent dispersion of the radioactive substances in the environment was thus accepted. Images taken by Greenpeace in 2000 with remote-controlled underwater cameras showed burst and corroded barrels on the seabed. Eduard Kiener, former Director of the Federal Office for Energy (BFE) commented in a radio broadcast on 12 June 2013 that „Government laws have to applied“, i.e. according to Kiener, waste dumping with subsequent bursting and corrosion of the barrels, the spreading of radioactive substances and transfer of these substances in the food chain was therefore “legal” and in conformity with national legislation.

Due to international pressure, sea dumping was discontinued in 1982 and banned in the London Convention in 1993. The working group on nuclear waste management of the Swiss Federal Government stated in 1983 that Switzerland had no alternative solution to sea dumping. Building and operation of interim storage facilities were the only temporary solution for the disposal of radioactive waste of all categories.

Radioactive waste management concepts were discussed worldwide in late 1950s until the 1980s. These concepts proposed some quite exotic solutions:

• Space disposal: Export of radioactive waste with missile transporters into space. -> However, this solution is far too unsafe (rockets may crash as „Challenger“ and „Columbia“ did) and too expensive.
• Subseabed disposal: Dumping and burial of waste canisters in the soft sediments of the ocean floor. -> The discovery of erosion of such sediments by ocean currents put an end to this solution. There was also a conflict with submarine mining (e.g. manganese nodules).
• Dumping in subduction zones at plate margins (e.g. in the Chile trench): In these zones, the waste would be absorbed under a continent by the plate subduction. -> However, possible obduction and the remobilisation of waste by volcanic processes make this option too risky.
• Dumping in polar ice caps: Dumping of waste in the centre of the icecap of Antarctica. -> Hot waste containers may melt through the ice and be flushed into the oceans by subglacial streams.
• Conversion (transmutation) of waste substances in substances with a shorter radioactive period. -> The method exists in research projects; high costs, high-energy requirements, time-consuming conversion processes.
• Guardianship: Waste is monitored over the next millennia in surface facilities. -> Ephemerality of human buildings, ephemeral social order, natural hazards (earthquakes, floods, etc.) are strong arguments against the adoption of this solution.

Since the 1950s, specialists in nuclear science endorse the confinement (containment) instead of dilution of radioactive waste. During his presidency, Jimmy Carter therefore funded a brainstorming group to elaborate a coherent strategy. In its report, the group presented the basis for the so-called “final disposal” of radioactive waste in deep geological repositories in the continental crust, applying the multi-barrier concept („Earth science technical plan for mined geological disposal of radioactive waste, ESTP“ DOE et al. 1979). This concept was the first systematically structured research and development option based on the barrier concept. A concept of several superimposed layers (Russian dolls principle) to prevent the radioactive waste from spreading into the environment, the biosphere and human habitat. Figure 4 bellow illustrates this multi-barrier approach:

Technical barriers:

• Robust waste form (e.g. vitrified waste, or radioactive substances in oxide form, with low solubility). -> Only weak solubility of the waste in contact with water.
• Canister (steel, copper, ceramics). -> Mechanical protection of the waste.
• Backfilling of the tunnel in the deep geological repository (clay, bentonite). -> Stabilisation of the tunnel and reduction of water and possibly gas flow.

Geological (natural) barriers:

• Host rock -> Rock with strong barrier effect for the reduction of water and gas flow and retention (adsorption) of radioactive materials.
• Stable geological environment -> Protection of a deep geological repository, e.g. from glacial erosion.

In 2000, EKRA (Swiss Expert Group on Disposal Concepts for Radioactive Waste) established, in addition to this multi-barrier system, further waste management measures for Switzerland, i.e. monitoring and possible retrieval of the waste.

Figure 4: Schematic view of the multi-barrier concept resembling a „Russian doll“: Superposition of barriers. Every layer has specific protective functions so as safeguard the environment from radioactive waste (Wildi, 2013).

The multi-barrier approach is now used worldwide as a basis for planning radioactive waste storage (Buser & Wildi 1981). However, no final radwaste storage for high radioactive waste has yet been implemented using this concept. This raises the question whether this is attributed to concept problems and implementation difficulties, or to the waste itself. Until such a storage concept can be implemented, the waste must be stored temporarily and over several generations, which is in stark contrast to the principle of sustainable management.

Launching of Swiss radwaste disposal projects

The use of nuclear energy began at a time when general technical optimism prevailed. In Switzerland, the economic, political and social sectors supported unreservedly the vision of a seemingly inexhaustible source of energy and thus laid the foundation for the industrial use of nuclear energy. Apart from a few critical voices, practically no one expected radwaste disposal to become such a major issue. Until the beginning of the sixties, radioactive waste from hospitals, research and industry was dumped in landfills. Regarding the handling of „nuclear ashes“, the Atomic Energy Act (Law on atomic energy) of 1959 contains no legal guidelines for the disposal of radioactive waste.

The entirely underestimated problem of radioactive waste disposal emerged only at the time when the first nuclear reactor was connected to the electricity grid. This also coincided with a growing antinuclear movement. In 1972, the operators of nuclear power plants and the Swiss Federal Government, responsible for waste disposal from the medical, research and industrial sectors, founded the National Cooperative for the Disposal of Radioactive Waste (Nagra). Following increasing resistance to new nuclear power plant projects, Swiss parliament decided in 1959 to complement the Atomic Energy Act. The urgent Federal Decree of October 1978 contained, for the first time, regulations relating to the disposal of radioactive waste. In a “Guarantee Project” (Projekt Gewähr), the owners of nuclear power plants had to merely demonstrate the feasibility of „permanent, safe management and disposal“ of radioactive waste. Operation of existing and licensing of new nuclear power plants depended on this „guarantee“ to be submitted by 1985. The terms of this project, which are comparable to the ones formulated in the Swedish model, also contain similar implementation measures. However, though the Swiss authorities provided a much longer timeframe than Sweden, i.e. six years for provision of such a „guarantee“, the ambitious goal proved completely unrealistic.

In spring of 1978, Nagra published its „Concept for nuclear waste disposal in Switzerland“. The authors described the potential host rocks proposed to receive the radioactive waste, the overall thickness of the geological formations and their regional distribution. For highly radioactive waste, priority was given from the beginning to the crystalline basement that slowly plunges from the Black Forest in Germany towards the southeast, under the thick Mesozoic and Tertiary sedimentary rocks of the Swiss Jura and the Swiss Plateau (“Mittelland”). These crystalline basement rocks were the targets of the first large-scale programme relating to the disposal of radioactive waste in Switzerland. The area included the north-eastern part of the country, south of the Rhine River, from Canton of Aargau to northern Canton of Zurich, Schaffhausen and Lake Constance.

In February 1979, Nagra submitted its comprehensive programme. The company intended to drill 12 deep wells in the selected area, crossing the sedimentary cover and penetrating as deep as 1 000 m into the crystalline rock. The wells should be cored, and rock samples should be recovered for laboratory and mechanical tests. In 1984, to complement these investigations, Nagra funded the Grimsel rock laboratory located in a tunnel system in the granite of the Alpine Aare massif.

Planned disposal categories

Nagra subdivided the waste to be disposed of into two storage categories:

1. Deep geological repository for high-level radioactive waste, vitrified fission products from reprocessing and spent fuel (HLW/SF).
2. Deep geological repository for low- and intermediate waste (L/ILW).

The assignment of alpha-toxic waste (ATW) to one or the other deep geological repository (HLW/SF or L/ILW) was to be decided at a later date when more information was available on the safety of the planned disposal sites and host rocks.

For waste with short radioactive life periods (waste with nuclides with half-lives of less than 60 days, or waste which falls below the threshold within 30 years after its formation), no deep geological disposal is required.

High-level radioactive waste HLW/SF disposal: (re)-discovery of the Permo-Carboniferous sediment trough of north-eastern Switzerland

Among the prospective 12 deep wells selected by Nagra, 7 were finally drilled (Figure 5, Table 1). Drilling started in spring of 1982. At the beginning, work progressed as planned. Beginning of May 1983, the tests revealed that the Weiach well had not reached crystalline rocks below the Triassic sediments, but a formation of red sand and clay sediments from the Permian time period, followed in greater depth by layers of coal seams of the Carboniferous period, and only at 2 km depth the crystalline basement. In the summer of the same year the Riniken well met a thick sediment sequence from the Permian time period and never reached the crystalline basin. Weiach and Riniken had obviously drilled into a so-called Permo-Carboniferous trough (sediment basin).

Figure 5: Extension of the Permo-Carboniferous (PC) trough of northern Switzerland and location of the 7 deep wells performed by Nagra (simplified after Diebold et al. 1991)

Table 1: Nagra deep wells within the context of “Projekt Gewähr“ (Guarantee Project) in north-eastern Switzerland

  Also, in wells that penetrated the crystalline basement, rocks were fractured and contained water. One single drilling section in the Böttstein well pointed to minor water permeability. Nagra used this particular result to try to provide “Project Guarantee” regarding final disposal of high-level radioactive waste in granite rocks. This rationale within the project „guarantee“, was, however, rejected by the Swiss government for the safe storage of highly radioactive waste, and crystalline rock formations lost their status as possible host rocks.

A short publication by the authors of this blog (Buser & Wildi 1984) retrace the history of this failure in providing the necessary “guarantee” for HLW/SF waste, i.e. the discovery of the Permo-Carboniferous trough was in fact a rediscovery, as petroleum companies had already described in a very general manner the existence of this sedimentary basin, hidden under Mesozoic sedimentary rocks. Also, some former geologists of these companies now worked as experts for Nagra, but had obviously not revealed the existence of the trough.

Figure 6: Remaining site regions in the crystalline basement of western Switzerland after the discovery of the Permo-Carboniferous trough (Buser & Wildi 1984, Figure 3). The remaining potential zones in the crystalline basement are displayed in blue.

Also, it must be noted that the Nagra deep wells, in particular the Weiach and Riniken wells, provided extensive and highly interesting information about the deep geology of northern Switzerland. Still, several questions on the geometry, deformation, stratigraphy, and hydrocarbon resources of this sediment trough remain unanswered.

Brief summary of the geological evidence on the formation and later development of the Permo-carboniferous trough of northern Switzerland

• At the end of the Paleozoic period, intense orogenic events affected Central Europe, with the intrusions of granitic magmas from the deep crust, and metamorphic transformations of rocks. These movements were almost (but not entirely) completed about 320 – 300 million years ago.
• In the whole area, major shear movements led to the collapse of elongated, E – W oriented trenches in the earth’s crust, including the so-called Permo-Carboniferous troughs. These movements also lifted up mountain ranges that were then eroded. The eroded material, gravel, sand, silt and clay, was deposited in the trenches and in depression during cooling and lowering of these zones. The older sediments are found today trapped and severely deformed in the trenches, the younger sediments form regular filling in gentle depressions above the trenches and the adjacent crystalline basement (Figure 7).
• During the Triassic period (250 – 210 million years ago) when the global sea level started rising and Central Europe was partially flooded (about 220 million years ago, “Muschelkalk Sea”), the land surface was almost flat.
• During the Jurassic period, starting 210 million years ago, sea level rise continued and marine sediments were deposited over large parts of Europe. The subsidence of the Earth crust was then more pronounced in the area of the former Permo-Carboniferous trough than in the Schwarzwald area to the North and the “Germanic land” in the area of the Swiss Plateau (Wildi et al. 1989).
• During the Alpine orogeny (formation of the Alps and the folded Jura), some of the limiting faults of the Permo-Carboniferous trough were reactivated, and some may still be seismically active nowadays (Naef & Madritsch (2014).

Figure 7: Schematic geological section of the Permo-Carboniferous trough and the overlying Jura Mountain range. This section was proposed by Diebold et al. (1991) using data from the Weiach and Riniken wells and seismic data. It was also inspired by a publication by Laubscher (1987). A more recent reinterpretation by Naef and Madritsch (2014) shows a somewhat simpler internal structure of the trough; however, it does not provide any new evidence regarding deep wells.

Sediments of the Permo-Carboniferous trough

The sediments of the Permian contain thick layers of clay, silt and sandy rocks, sometimes also conglomerates and carbonate deposits. Often plant residues and other organic material were observed in the cores. These sediments have been deposited on large alluvial fans, in rivers and lakes. As so often in similar deposits, for example, in the Alps, there is evidence of the presence of ore deposits.

The sediments of the Carboniferous period, which were drilled in Weiach between 1447 and 2020 metres depth, are of a particular interest. They are of great variability, with intercalations of coal seams in sandy and clayey sequences, namely between 1557 m and 1751 m depth. High concentrations of organic matter are also found above and below these coal seams. During burial, organic matter was transformed into coal. On the other hand, natural gas (methane) may have migrated from organic rich layers to porous sediments, e.g. sand stones, and accumulated as „conventional natural gas“ in traps. If migration has not occurred, gas may still be present as „unconventional gas“, i.e. “tight gas” or “shale gas” in shaly sediments.

The deeper central parts of the Permo-Carboniferous trough have not been drilled and the nature of the filling is therefore not known yet. Based on the interpretation of the seismic profiles, the authors suspect similar deposits as in Weiach, which may indicate significant coal and gas reserves.

Low- and medium-level radioactive waste – the Wellenberg project

The Wellenberg project was the last of its kind under the 1959 Atomic Energy Act and the urgent Federal Decree of October 1978. The project was initiated as part of the “Guarantee Project”, i.e. to demonstrate the feasibility of „permanent, safe management and disposal“. The project failed on 22 September 2002, when the citizens of the Canton of Nidwalden refused in a popular vote to grant a permit for further geological investigations by Nagra.

A brief historical analysis reveals “what can go wrong” in a disposal project. At the beginning of the process, Nagra proposed 100 siting regions as potential storage facilities exhibiting different host rocks for the construction of a deep geological repository for low- and medium-level radioactive waste:

• 23 regions with anhydrite host rocks.
• 15 regions with Alpines shaly and marly rocks.
• 25 regions with Opalinus Clay (a Jurassic clay formation in the Jura and Swiss Plateau areas).
• 23 regions with potential host rocks protected by overlying geological barriers.
• 14 regions with crystalline host rocks (granites and gneiss).

Among these potential sites, Wellenberg, located in the Alps of Central Switzerland (Canton of Nidwalden), was listed under the name “Altzellen“. Among the best classified sites was “Oberbauenstock”, close to “Altzellen”, with the ranking “good”, in other words appropriate for a deep disposal; “Altzellen” was also ranked as “good”, but was only rated “average” due to the available geological information. From 1979 to 1985 the following three sites were selected as part of the “Guarantee Project”:

• Bois de la Glaive (in anhydrite host rocks).
• Piz Pian Grand (in metamorphosed Alpine rocks).
• Oberbauenstock (in Alpine marly rocks, the so-called “Palfries Marls”).

Figure 8: Wellenberg: “The green mountain“ in the Canton of Nidwalden (photo: https://www.kernenergie.ch/de/genossenschaft-entsorgung.html).

Based on the geotechnical findings of the Seelisberg highway tunnel, in the heart of the Oberbauenstock massif, the so-called Palfris marls were finally selected as the host rocks to conduct the feasibility study for the disposal of low- and intermediate-level radioactive waste.

After 1985, the “Altzellen” site (now “Wellenberg”) was added to the three already selected sites. This reclassification was conducted as follows (KFW 2002a):

In December 1985, Nagra asked the President of the Cantonal Council of the Canton of Nidwalden whether the Government would agree to an extension of the investigation area to find a suitable disposal site. Possible reasons for extended investigations were unfavourable exploration conditions in the steep mountainous Oberbauenstock area and a suitable extension of the list of possible sites as part of the selection programme.

In January 1986, the Government agreed to Nagra’s request for preliminary investigations in an extended area. The Government justified its decision as an effort to contribute to the solving of an environmental protection problem of national importance. Furthermore, the positive economic impact derived from the implementation of a repository in the Canton of Nidwalden was addressed.

Figure 9: Simplified section of the planned L/ILW disposal (upper level) and alpha-toxic radioactive waste (lower level) at the Wellenberg site (KFW 2002a).

Following preliminary investigations, Nagra favoured “Altzellen” (new: „Wellenberg“) over the “Oberbauenstock” and other sites. Also, the selection of the Wellenberg site represented a clear deviation from the original selection procedure.

In 1987, Nagra applied for a permit for further geological investigations, such as horizontal and vertical wells to investigate the main space for the deposit and a deeper area for the disposal of “alpha-toxic waste” with longer disintegration periods than L/ILW; this was an attempt to expand the waste inventory to a higher risk category than initially planned (KFW 2002b).

Based on a comparison with the three other sites, Bois de la Glaive (Canton of Vaud), Oberbauenstock (Canton of Nidwalden) and Piz Pian Grand (Canton of Grisons) and following several field investigations, Wellenberg finally ranked first on the list of potential sites for disposal of low- and medium-level radioactive waste.

In 1994, Nagra established a local company, the Cooperative for Nuclear Waste Management Wellenberg (GNW). GNW applied for a Federal license for the repository of low- and intermediate-level radioactive waste and a concession from the Canton in compliance with the mining code. On 25 June 1995 and based on the mining code, the citizens of the Canton of Nidwalden rejected the application with 52% of the votes (for a detailed history, see Hadermann et al. 2014).

However, the project was not yet dead. After the drafting of a new disposal concept by the group of experts „Disposal Concepts for Radioactive Waste“ (EKRA 2000), the Federal Government and the executive of the Canton of Nidwalden funded an other expert group (KFW, Kantonale Fachgruppe Wellenberg) to review the site selection procedure, to clarify the waste inventory for the Wellenberg site and to establish the go/no-go criteria for the selection (KFW 2002 a, b).

Despite all these efforts, the population rejected in a cantonal poll on 22 September 2002, with 57% of the votes, the Nagra-GNW application for the construction of an exploration gallery for the waste disposal facility. The following year, 2003, the local cooperative GNW was liquidated.

Discussion

The reasons of why the Wellenberg project had failed have never been properly elucidated. Also, due to this failure, a 30-year effort and a large amount of money has been invested à fonds perdu in Lake Lucerne. Was it the Alpine location near the earthquake zone of Sarnen, which made the voters sceptical? Or, was it the non-transparent intentions of Nagra, or the lack of clear evaluation criteria? Or maybe just the selfish attitude of the citizens who were not prepared to assume the „national burden“? Or even simpler: Had the opposing NGO (Committee for the participation of the people of Nidwaldnen, GNW) just won a fierce battle?

Since these questions will and cannot be answered, we shall try to filter out some key problems regarding the Wellenberg site selection procedure:

• Site selection: The Wellenberg site selection deviated from the official procedure and was the result of „tactical manoeuvring“ between Nagra-GNW on the one hand, and the government on the other; this was certainly not appropriate in gaining the trust of the population concerned.
• Lack of transparency: Though an informal clarification regarding the nature of the waste was provided at the last moment before the popular vote, a deep mistrust arose among the citizens, since a future waste disposal inventory could not be guaranteed by any of the parties involved.
• Wrong location: The security agencies and numerous professionals outside the official structures were truly convinced of the potential suitability of the Wellenberg site. Other voices, however, drew attention to the problem of long-lived radioactive waste in an Alpine location, in particular regarding the potential of erosion in a future glaciation.
• Reliability of the site selection procedure: Finally it should be noted that none of the selected locations of the „Guarantee Project“ (Bois de la Glaive, Piz Pian Grand, the Oberbauenstock or Wellenberg) would currently be accepted as radwaste disposal sites. Therefore, the question can rightly be raised on the validity of the „Guarantee Project“ according to the Nuclear Energy Act.

Opalinus Clay – A new universal host rock

Due to the absence of an appropriate disposal site, the authorities rejected “Project Guarantee” based on crystalline geological formations as host rocks for HLW/SF waste. In its decision of 3 June 1988, the Swiss Federal Council therefore asked the owners of nuclear power plants (and in fact Nagra) to extend their investigations also to sedimentary rocks as host rocks and disposal sites. This decision paved the way to the “Opalinus Clay Project” as a new attempt to implement the „Guarantee Project”.

This official story does not reveal the long struggle between Nagra and the various external expert committees, e.g. the Commission for Nuclear Waste Management (KNE), but also within Nagra, to dismiss the crystalline basement. The experience gained since the start of the programme in 1979 revealed that the depth of the crystalline rock basement in north-eastern Switzerland could be investigated only by deep wells. Therefore, information on the geological structure, deep groundwater flow etc., were only known for the drilled sections and could not be extrapolated laterally. Reflections on seismic and other geophysical investigation methods did not provide this complementary information. Thus, each potential storage site remained subject to considerable uncertainty in the crystalline rock. In fact, this also applies to the highly acclaimed projects in Sweden and Finland.

This situation greatly differs in many sedimentary rocks. The new concept developed by Nagra planned to investigate the Opalinus Clay formation that extends under the whole surface of the Jura Mountains and the Swiss Plateau of almost 100-m thickness. This clay formation was deposited at the beginning of the Middle Jurassic period. In this second attempt to demonstrate „permanent, safe management and disposal“ for the HLW/SF waste category, Nagra (2003) specifically mentions the following favourable qualities of this rock formation:

• Lateral continuity of the lithology, whereby small lateral differences may be observed (for example changing sand content, intercalation of limestone layers, etc.).
• Self-closure of fractures: Clay swells when exposed to moisture and thus closes the existing cavities. However, this quality depends on the temperature, the mineralogical composition of the clay and mineralisation of the water. The rocks are therefore basically hardly permeable to water and gas circulation. Radioactive substances can be adsorbed on the clay minerals and do not reach the groundwater when ascending to the Earth surface.
• Interesting properties for geophysical investigations: Clay can be investigated easily (from the surface) by seismic reflection methods. Vertical tectonic dislocations of more than about 5 to 10 metres can be detected at a distance. However, exploratory drillings and calibration are essential for calibration and more detailed studies, in particular regarding geotechnical and hydrogeological parameters.

However, argillaceous rocks are also characterised by some disadvantages as host rocks for deep geological repositories. This concerns in particular their relative fragility relative to the construction of galleries and tunnels (especially horizontal or only slightly inclined tunnels). Horizontally-mined cavities do not tolerate high pressure from the overlying rocks nor gas and water pressure within the rock formation. The ingress of water into underground tunnel systems is particularly dangerous, as the clay rock can be softened and the cavities collapse.

In its “Project Guarantee” regarding disposal in the Opalinus Clay formation in the northern Canton of Zurich, (the so-called Weinland area), Nagra (2003, 2005) not only claimed to have found the best possible host rock formation, but also the right location for a disposal facility. It therefore requested the Federal Council:

• „To approve “Project Guarantee” since it met the provisions issued in the decision of the Federal Council of 3 June 1988.
• To focus future investigations regarding a deep geological disposal site for spent fuel, vitrified high-level waste and long-lived intermediate-level waste in Switzerland on the Opalinus Clay as a host-rock and potential siting area in the Zurich Weinland area. [1]„

The Federal Council approved the first request with numerous additional restrictive practices, but demanded from Nagra the investigation of additional siting regions and host rocks. In a summary report of 2005, Nagra met, at least partly, the prescribed requirements as described in the „Sectoral Plan for Nuclear Waste Disposal“ (see bellow).

EKRA: A new concept for monitoring radioactive waste disposal

After the first popular vote on the Wellenberg project, Moritz Leuenberger, the Federal Councillor (Minister) in charge of the Federal Department of the Environment, Transport, Energy, and Communication DETEC funded an interdisciplinary working group to develop a concept for monitoring long-term waste management and study the question of retrievability. The first report of this “Group on Disposal Concepts for Radioactive Waste” (EKRA) was published in January 2000. The concept developed by EKRA is based on three basic findings:

➢       Responsibility for the safe disposal of radioactive waste is to be assumed by those profiting from the generation of electricity produced by the nuclear power plants.

➢       Currently, deep geological repositories in appropriate host rocks in a stable geological context prove to be the only internationally recognised method for the safe and long-term disposal of radioactive waste.

➢       Monitoring of the repositories and the possibility to retrieve the waste if necessary are requested by a large part of the general public.

EKRA’s ethic requirements for a sustainable and safe repository have therefore been formulated as follows:

➢        Guarantee for the permanent protection of humans and the environment.

➢        No undue burden on future generations.

➢        No undue restrictions of options for future generations.

➢        Possibility for corrective actions.

➢        Adequate public decision-making process for repository implementation.

From a technical viewpoint, EKRA submitted a concept based on a deep geological repository combining three different facilities (Figure. 10):

• Test facility: This facility serves as a rock laboratory for site-specific studies necessary for the safety demonstration required for the operation of the repository. The facility is constructed once the site has been selected and may remain in use during the operation of the main facility.
• Main facility: Most of the waste is disposed of in this facility. The architecture of the facility (access, cavern system for the disposal and its geometry), the installation and the backfilling have to be conceived and realised in a way that retrieval remains a technical option. Once the waste has been emplaced in the caverns, these are backfilled and sealed. However, access and service tunnels will remain open, and waste can be retrieved without any excessive effort and at relatively low costs, e.g. using remote-controlled tunnelling equipment. The time of closure and sealing of the facility will be decided by the Swiss Government.
• Pilot facility: This is a key facility of the technical part of the concept of monitoring and reversibility. Representative volumes of the different waste types and waste forms will be deposited in this separate pilot facility, with the aim to validate long-term predictions as well as identify possible early indications of safety barrier failures. The main functions of the facility are the following:

➢  Monitor the long-term evolution of the engineered barriers and the near-field.

➢  Verify the predictive models to demonstrate long-term safety.

➢  Serve as a demonstration facility to allow long-term control beyond the closure of the Test and Main facility.

Figure 10: Schematic concept and system components of the monitored, long-term geological disposal facility according to EKRA (2000).

Relating to the Pilot facility, the following activities are planned:

➢  Monitoring of the engineered and near-field natural barriers (host rock). Development of monitoring instrumentation and their replacement due to ageing and technical progress.

➢  Repairs and improvements of the engineered barriers.

➢  Tests on clean-up measures in the event of unexpected release of radionuclides into the near-field and geosphere.

➢  Development of waste retrieval techniques.

Sealing and closure of the facility (or the retrieval of waste from the Pilot facility) will be decided at a later date and depend on the experience and monitoring results.

Aside from this technical part, EKRA also recommended in its first (EKRA 2000) and second report (EKRA 2002), institutional and organisational measures, including a scheduled management of radioactive waste disposal. Among these recommendations, mention should be made of: The need of a permanent public debate to resolve the problem; the need to adapt the legislation to the requirements of the waste disposal concept, including monitoring and the option of reversibility; the need of a clear schedule and follow up of the concept; the need of independence from waste producers and the agency in charge of implementing the disposal concept (Nagra); the need of independent research to guarantee the scientific follow-up of the concept, as well as the transfer of know-how.

The concept for long-term geological disposal monitoring has been widely accepted by public opinion. Some parts have also been implemented, others have not been considered yet.

Implemented components of the EKRA concept:

• The technical aspects of the EKRA concept have been stipulated in general terms, and partly in detail, within the frame of the law and ordinance on nuclear energy.
• The establishment of a detailed technical disposal concept has also been included in the law.
• Implementation, including a detailed schedule for site selection and mechanisms of public involvement, has been laid down by the Swiss Federal Government in the Sectoral Plan for Deep Geological Repositories (see bellow).

Not implemented components of the EKRA concept and open questions:

• Switzerland still grossly lacks independent research on long-term disposal questions, as well as in the field of social, natural and engineering sciences. Most research is funded by and depended on the waste producers. No university level educational programme (ex. PhD degree) is oriented towards key aspects of long-term storage.
• The agency in charge of the disposal concept (Nagra) is still exclusively dependent on the waste producers. This may be negatively perceived by public opinion.
• Questions on the technical and institutional aspects of long-term monitoring and reversibility, as outlined by EKRA, have not been comprehensively developed and still need to be defined.
• Coordination of the technical aspects of radioactive waste disposal remains difficult; in particular questions related to waste quality (gas producing components), further technical aspects and questions related to the Sectoral Plan for Deep Geological Repositories.

Law on nuclear Energy

In the field of nuclear waste disposal, the Nuclear Energy Act (NEA 2003) was strongly influenced by the Wellenberg Project, and in particular by the strong local popular resistance to the selected site for L/ILW waste disposal. Moreover, several parts of the EKRA concept have been included in the law, under the term “deep geological disposal”. This term replaced the traditional designation of “final disposal”. The following aspects of the law are of particular interest with regard to the disposal of radioactive waste:

• 32: The waste producers (and Nagra) are liable to submit a detailed waste disposal concept and regular updates.
• 33: Should the waste producers be unable to dispose of the radioactive waste, the Swiss Confederation may have to assume this task (but not the costs!).
• 34: Regulation on the export of radioactive waste.
• 40: Integration of surface facilities into land planning regulations.
• 40: Regulation on the marking of the disposal sites for future generations.
• 44, 49: Participation and curtailing the competence of the cantons, eliminating the right of veto in the cantonal legislation.
• 77 – 82: Financing nuclear decommissioning and waste disposal by a fund.

As a further measure to silence critical voices, parliament amended the law by dissolving the Swiss Federal Nuclear Safety Commission (NSC) in 2007 and replacing it by a smaller and less critical Swiss Federal Commission for Nuclear Safety (CNS).

 Sectoral Plan for deep Geological Repositories

The creation of the „Sectoral Plan for Deep Geological Repositories“ (hereafter referred to as Sectoral Plan) is based on Article 40 of the Nuclear Energy Act, which integrates the location of surface facilities that belong to deep geological repositories in the land and space planning process. Its implementation is conducted in compliance with the Swiss Federal Spatial Planning Act (Raumplanungsgesetz, RPG), which stipulates in its Art. 13 „The Federal Government develops principles to perform its spatially relevant tasks; it creates the necessary strategies and Sectoral Plans and coordinates them with one another.” „According to the Space Planning Ordinance (Raumplanungsverordnung, Art. 14), the Federal Government defines „strategies and Sectoral Plans for the planning and coordination of its tasks, insofar as these would affect in a significant way space and environment.”

The Sectoral Plan was introduced in 2004. In a discussion between the former Federal Councillor Moritz Leuenberger and Nagra, it was agreed that the site selection procedure should propose a number of alternative sites, so as to offer selectable options. These alternatives would have to be examined and assessed according to the procedure of the Sectoral Plan and in compliance with the Spatial Planning Act (Raumplanungsgesetz, RPG). In a 1997 planning document of the Swiss Confederation („Strategies and Sectoral Plans of the Confederation”), a Sectoral Plan on „Nuclear Waste Disposal“ is listed as „in preparation.“

Early 2005, the Swiss Federal Nuclear Safety Inspectorate (HSK, now ENSI) and the Swiss Federal Nuclear Safety Commission (NSC, KSA) started working on geological safety criteria for site selection. The overall picture of the Sectoral Plan, including aspects related to the planning of surface facilities in compliance with the RPG, appeared one year later. At that time, nuclear safety specialists from HSK, NSC and even from Nagra showed little enthusiasm for the project. They mainly questioned the order of priorities between spatial planning and safety of nuclear waste disposal. Important legal and regulatory components of the Sectoral Plan also appeared to have been edited by Nagra. This led to a diplomatic incident with the NSC (on 1 June 2006) and to a clarifying conversation between the Federal Office of Energy, the HSK and NSC. This resulted in the establishment of transparent communication rules between the Inspectorate HSK and Nagra. However, Nagra obviously sustained its involvement in formulating administrative and legal texts.

On 2 April 2008, the Federal Council approved the Sectoral Plan. This plan is subdivided into the following stages prior to site selection for deep geological repositories comprising all waste categories:

Stage 1: Selection of geological siting areas for each L/ILW and HLW/SF.

Stage 2: Selection of at least two sites each for L/ILW and HLW/SF.

Stage 3: Site selection and general licensing procedure for L/ILW and HLW/SF.

The plan also introduced a complex web of consultative bodies, both at federal and regional level.

On 6 November 2008, the Federal Office of Energy published Nagra’s proposals for the siting regions (Figure 11). The following sites were proposed for L/ILW waste disposal: Südranden, Zurich Northeast (Zurich Weinland), North of Lägern, Jura East (Bözberg), South of Jura range and Wellenberg. Zurich Northeast (Zurich Weinland), North of Lägern, Jura East (Bözberg) for HLW/SF waste disposal. Since the nuclear safety authorities agreed to these proposals in 2010 and the Federal Council in 2011, Nagra continued to evaluate all the proposed areas in Stage 2.

Figure 11: Selected areas for L/ILW and HLW/SF waste disposal in Stage 1 of the Sectoral Plan: 1) Südranden, 2) Zurich north-east (Zurich Weinland), 3) North of Lägern, 4) Jura East (Bözberg), 5) South of Jura range und 6) Wellenberg.

All the regional and conceptual consultations were funded at the beginning of Stage 2. The weaknesses and errors of the Sectoral Plan were visible right from the beginning:

• In the Sunday newspaper “SonntagsZeitung” („nuclear factories“) of 17 July 2011, a Nagra spokesman declared that the surface installations of the deep geological repository also included „hot cells“ for treatment and waste conditioning. He was promptly questioned by concerned citizens on the reason for and use of “hot cells” in a waste disposal site?
• In December 2011, Nagra submitted the proposals for the siting of surface facilities of the deep geological repositories. These proposals are supposed to serve as discussion basis for the regional consultation process. However:
  • All the Nagra sites are located on local or regional groundwater reservoirs and/or exposed to natural hazards.
  • Some of the facilities are planned in close proximity of villages, including the hot cell installations.
  • As the geological storage sites are not yet determined, Nagra plans access to all nuclear waste disposal locations from the surface via an inclined tunnel and railway, thus taking into account additional risks.

Thus, the fear expressed by nuclear safety specialists regarding the Sectoral Plan procedure is justified, i.e. the RPG (territorial planning) arguments favoured the procedure over nuclear safety.

During the regional discussion in autumn 2011, a press release hit the news like a bomb: The participants involved in the consultation process were informed by the press that the game had been decided long ago. On 7 October 2012, the Sunday newspaper “SonntagsZeitung” published the Nagra working paper AN11-711 “The exploration strategy in the context of the Sectoral Plan”. This official paper reveals Nagra’s direct exploration strategy of the Zurich Weinland and Bözberg sites. The paper had been signed on 18 November 2011, at about the same time when regional conferences started their work: While citizens debated on waste disposal sites in six regions, a Nagra panel worked in Wettingen on a strategy to reduce the impact of these regional conferences. The authorities, in particular Dr W. Steinmann, Director of the Swiss Federal Office of Energy, were offended by the paper (and even more by its publication) and promised at a press conference that Nagra would be monitored far more closely from now on. However, on 30 January 2015 Nagra proposed the two sites selected in 2011, i.e. Bözberg and Zurich Weinland.

This Blog discusses several key aspects over the past four years related to the site selection procedure over the Sectoral Plan, and also looks into the future with the aim to enhance nuclear safety. Key articles will be published both in German and English.

References (cited or used in this text)

BFE 2011: Sectoral Plan for Deep Geological Repositories, Conceptual part. Federal Office of Energy, CH-3003 Bern, Switzerland. https://www.bfe.admin.ch/radioaktiveabfaelle

Bläsi, H.R., Kleboth, P. & Liniger, M. (1999): Sondierbohrung Benken: Bohrstellengeologie (Stratigraphie, Strukturgeologie, Laboranalysen). Unpubl. Nagra Int. Ber.

Bläsi, H.R., Peters, T. & Mazurek, M. (1991): Der Opalinus-Ton des Mt. Terri (Kanton Jura): Lithologie,

Mineralogie und physiko-chemische Parameter. Unpubl. Nagra Int. Ber.

 Buser, M. & Wildi, W. 1981: Wege aus der Entsorgungsfalle. – Schweiz. Energiestiftung (Zürich), Report n° 12, 257p.

Buser, M. & Wildi, W. 1984: Das Gewähr-Fiasko. Schweizerische Energiestiftung, Zürich, 52.

Diebold, P., Naef, H. & Ammann, M. 1991: Zur Tektonik der zentralen Nordschweiz. NAGRA, NTB 90-04, Wettingen.

DOE & USGS 1979: Earth science technical plan for mined geological disposal of radioactive waste, ESTP“, Department of Energy and U.S. Geological Survey, TID-29018 (Draft).

Dürrenmatt, F. 1991: Labyrinth, Stoffe I-III, Der Winterkrieg in Tibet, S. 49.ff. und Turmbau, Stoffe IV-IX, Begegnungen, S. 323.ff. und Querfahrt, S. 353.ff., Gesammelte Werke 6, Diogenes Zürich.

EKRA, Expertengruppe Entsorgungskonzepte für radioaktive Abfälle 2000: Entsorgungskonzepte für radioaktive Abfälle: Schlussbericht. Bern: Bundesamt für Energie.

Hadermann, J., Issler, H. & Zurkinden, A. 2014: Die nukleare Entsorgung in der Schweiz 1945 – 2006, Verlag NZZ, 200 S.

HSK 2005: Gutachten zum Entsorgungsnachweis der Nagra für abgebrannte Brennelemente, verglaste hochaktive sowie langlebige mittelaktive Abfälle (Projekt Opalinuston).

Hufschmied, P., Wildi, W., Aebersold, M., Appel, D., Buser, M., Dermange, F., Eckhardt, A. & Keusen, H.R. 2002: Monitored long-term geological disposal” – A new approach to the disposal of radioactive waste in Switzerland. Transact. Europ. Nuc. Conf., Europ. Nuc. Soc., Bruxelles, 8 p.

Hug, P. 1987: Geschichte der Atomtechnologie – Entwicklung in der Schweiz. Lizenzarbeit Univ. Bern.

KEG, Kernenergiegesetz vom 31. März 2003.

Kreuzer, K. 1992: Ein Hüte-Konzept für radioaktive Abfälle, neue Wege, März 1992, 86-Jahrgang, Nr. 3.

Laubscher, H.P. 1987: Die tektonische Entwicklung der Nordschweiz. Eclogae geol. Helv. 80/2, 287-303.

LENu 2003: Loi du 21 mars 2003 sur l’énergie nucléaire. Swiss Confederation, law N° 732.1.

Milnes, A.G., Buser, M. & Wildi, W. 1980: Endlagerungskonzepte für radioaktive Abfälle im Ueberblick. Z. dtsch. geol. Ges. 131, 359-385.

Naef, H. & Madritsch, H. 2014: Tektonische Karte des Nordschweizer Permokarbontrogs. NAGRA, NAB-14-17, Wettingen.

Nagra 1987: Sondierbohrung Riniken, Geologie technischer Bericht 86-02. 198 S.

Nagra (2001): Sondierbohrung Benken – Untersuchungsbericht. Nagra Tech. Ber. NTB 00-01. (Text- und Beilagenband).

Nagra 2002: Projekt Opalinuston, Synthese der geowissenschaftlichen Untersuchungsergebnisse, Entsorgungsnachweis für abgebrannte Brennelemente, verglaste hochaktive Abfälle, sowie langlebige mittelaktive Abfälle. Technischer Bericht 02-03.

Nagra 2003: Projekt Opalinuston, Entsorgungsnachweis für abgebrannte Brennelemente, verglaste hochaktive Abfälle sowie langlebige mittelaktive Abfälle. zusammenfassender Überblick, 2. ergänzte Auflage.

Nagra 2005: Geologische Tiefenlagerung der abgebrannten Brennelemente, der hochaktiven und langlebigen mittelaktiven Abfälle. Darstellung und Beurteilung der aus sicherheitstechnisch- geologischer Sicht möglichen Wirtsgesteine und Gebiete Technischer Bericht NTB 05-02.

Nagra 2008: Vorschlag geologischer Standortgebiete für das SMA- und das HAA-Lager ; Darlegung der Anforderungen, des Vorgehens und der Ergebnisse. Technischer Bericht NTB 08-03, Wettingen, 428 S.

OENu 2004: Ordonnance du 10 décembre 2004 sur l’énergie nucléaire. Swiss Confederation, ordinance N° 732.11.

Wildi, W., 2012: Reversibility and retrivability in planning for geological disposal of radioactive Waste (Proceedings of the R&R international conference and dialogue, 14 – 17 December, Reims, France): Radioactive Waste management; 2012, OECD – NEA, Issy les Moulineaux.

Wildi, W., 2013, Stockage des déchets nucléaires: Aqua and Gas, v. 2013, no. 4, p. 76-81.

Wildi, W., Appel, D., Buser, M., Dermange, F., Eckhardt, A, Hufschmied, P., Keusen, H.R. & Aebersold, M. Expert 2000: Disposal concept for radioactive waste. EKRA – Report I, Group on Disposal Concepts for Radioactive Waste, EKRA, Federal Office of Energy, CH-3003 Bern, Switzerland.

Wildi, W., Appel, D., Buser, M., Dermange, F., Eckhardt, A, Hufschmied, P., Keusen, H.R. & Aebersold, M. Expert 2002: Umsetzung von Entsorgungsstrategien in der Schweiz. EKRA – Report II, Group on Disposal Concepts for Radioactive Waste, EKRA, Federal Office of Energy, CH-3003 Bern, Switzerland.

Wildi, W., Funk, H.P., Loup, B., Amato, E. & Huggenberger, P. 1989: Mesozoïc subsidence history of the European marginal shelves of the Alpine Tethys (Helvetic realm, Swiss Plateau and Jura). Eclogae geol. Helv. 82/3, 817-840.

• [1] „Von der Erfüllung der Auflagen zum Projekt Gewähr gemäss Beschluss des Bundesrats vom 3. Juni 1988 sei im zustimmenden Sinne Kenntnis zu nehmen und der Entsorgungsnachweis als erbracht zu genehmigen.
• Der Fokussierung künftiger Untersuchungen in Hinblick auf eine geologische Tiefenlagerung der abgebrannten Brennelemente, verglasten hochaktiven Abfälle sowie langlebigen mittelaktiven Abfälle in der Schweiz auf den Opalinuston und das potentielle Standortgebiet im Zürcher Weinland sei zuzustimmen.“