Final Disposal of High-level Radioactive Waste in Germany

Transcription

1 Energy Final Disposal of High-level Radioactive Waste in Germany The Gorleben Repository Project

2 Editorial department Federal Ministry of Economics and Technology (BMWi) Design and production PRpetuum GmbH, Munich Print Silber Druck ohg, Niestetal Photo credits BMWi Publisher Federal Ministry of Economics and Technology (BMWi) Public Relations/IA Berlin The Federal Ministry of Economics and Technology has been awarded the berufundfamilie audit certificate for its family-friendly HR policy. The certificate is granted by berufundfamilie ggmbh, an initiative of the Hertie Foundation. Last Revised October 2008

3 Energy Final Disposal of High-level Radioactive Waste in Germany The Gorleben Repository Project

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5 3 Preface Today, nuclear power stations play an important role in the stable and cost-effective supply of electricity in Germany. Regardless of the outcome of debates on the future of nuclear energy in Germany, existing and future radioactive waste has to be disposed of safely and securely for extended periods. On account of our responsibility towards present and future generations, we need to take an objective approach based on scientific findings for the final disposal of radioactive waste. In the opinion of the BMWi, finding a solution to the repository issue should not be treated as a political football by divergent political interest groups. Supporters and opponents of nuclear energy alike should be equally committed to urgently addressing the issue of final radioactive waste disposal with a view to achieving prompt results. Our citizens rightly expect politicians and policymakers to exercise responsibility here. In this legislative term, the Federal Government made important decisions concerning the final disposal of low and medium-level waste, which account for approximately 90percent of the waste volumes forecast. The Konrad mine repository is to go into operation in 2013 for this purpose. A lot of controversy does, however, surround the further course of action to be taken for high-level radioactive waste. Exploration work has been underway at the Gorleben salt dome since 1979 for this very purpose. A moratorium on exploration has been imposed since 2000 even though the results of the exploration have been positive up to now, and the questions which gave rise to the moratorium have been answered. The next steps to be taken in resolving the repository issue are a source of controversial political debate. Arguments against further exploration in Gorleben are the alleged unsuitability of the salt dome, as well as demands to look for new repository sites in alternative host rocks. These arguments often ignore the scientific findings and results of the exploration conducted at the Gorleben salt dome over the past number of decades. In its capacity as the ministry responsible for fundamentals-oriented research on repositories, the BMWi has summarised the findings on the Gorleben salt dome in this brochure. The conclusion reaffirms the ministry s call to continue open exploration of the Gorleben salt dome. Only in this way a final statement on the suitability of Gorleben can be made, which will be the basis for further decisions on the final disposal of heat-generating high-level radioactive waste in Germany. Federal Minister of Economics and Technology

6 4 Table of Contents I. Introduction II. Why should rock salt be used for the final disposal of high-level radioactive waste? III. Gorleben repository project How was the Gorleben salt dome chosen? How far has exploration work progressed at the Gorleben salt dome? Why does the exploration moratorium still apply? IV. State of research Alternatives to rock salt in Germany Basic research within the responsibility of the Federal Ministry of Economics and Technology Can Gorleben be compared to the Asse II mine? V. Would it make sense to look for new repository sites? VI. Roadmap to a repository for high-level heat-generating waste Continuing and completing exploration work at the Gorleben salt dome Safety assessment and international verification Putting the repository into operation VII. Summary VIII. Literature IX. Annexes

7 5 Table of Figures Fig. 1: Geographical location of the Gorleben salt dome in Lower Saxony Fig. 2: Aerial photo of the Gorleben site Fig. 3: Properties of potential host rocks in Germany which are relevant for repository concepts Fig. 4: Fig. 5: Fig. 6: Location of the salt structures appraised by Richter-Bernburg & Hofrichter (1964) with regard to their suitability for the final disposal of radioactive waste Distribution of the sites examined in greater detail with regard to their suitability as a radioactive waste management center as part of the Federal Government site selection process (KEWA study) Location of the sites examined in greater detail with regard to their suitability as a radioactive waste management center as part of the site selection process conducted by the Land of Lower Saxony Fig. 7: Simplified geological section through the Gorleben salt dome Fig. 8: Section through the salt dome with excavations Fig. 9: Three-dimensional model of the outer shell of the Gorleben salt dome with the location of the mine workings Fig. 10: View of the gait road at the 840m level Fig. 11: Historical profile of exploration work at the Gorleben salt dome Fig. 12: Excavations with EB1 and areas still to be explored Fig. 13: Excavation work in a drift at the 840m level Fig. 14: Survey map of the regions with argillaceous rock deposits and salt domes in Germany which could be considered for the final disposal of high-level waste Fig. 15: Schematic illustration of a repository system in a deep geological formation Fig. 16: Demo experiments for direct final disposal Fig. 17: Comparison of the various repository concepts Fig. 18: Road headers at the Gorleben exploration mine Fig. 19: Diagram of the stages of development of the salt structures found in Germany Fig. 20: Salt structures in Northern Germany

8 6 List of Annexes Annex 1: Rock salt: recommended as a host rock for the final disposal of high-level waste Annex 2: 1964 selection procedure implemented by the Federal Institute for Soil Research Annex 3: Selection process applied by the Federal Government for an WMC in the period between 1973 and 1976 (KEWA study) Annex 4: The four phases of the selection process applied by the Land of Lower Saxony in 1976/ Annex 5: Examples of how repository sites have been identified worldwide Annex 6: Additional results of exploration work conducted to date on the Gorleben salt dome Annex 7: Annex 4 on the agreement on June 14, Annex 8: Important points of the public debate in Wendland on the exploration of the Gorleben salt dome Annex 9: Primary results of the BGR studies on crystalline rock, argillaceous rock and rock salt as host rocks Annex 10: Frequently asked questions on Gorleben

9 7 List of Abbreviations AkEnd BfS BGR Committee on a Site Selection Procedure for Repository Sites Federal Office for Radiation Protection Federal Institute for Geosciences and Natural Resources BMBF Federal Ministry of Education and Research } BMFT Federal Ministry for Research and Technology in legal succession BMwF Federal Ministry for Scientific Research BMI BMU BMWi DoE EB 1 IAEA IMAK HLW KEWA NLfB NMU OECD/NEA PTB PTKA-WTE Federal Ministry of the Interior Federal Ministry for the Environment, Nature Conservation and Nuclear Safety Federal Ministry of Economics and Technology Department of Energy (USA) Exploration area in Gorleben salt dome International Atomic Energy Agency Interministerial task force High-level waste Nuclear fuel reprocessing company State Office of Lower Saxony for Soil Research Ministry for the Environment and Climate Protection of Land Lower Saxony Organization for Economic Co-operation and Development/Nuclear Energy Agency National Metrology Institute Project Management Agency Forschungszentrum Karlsruhe Water Technology and Waste Management Division Project RSK WMC Reactor Safety Commission Radioactive waste management center

10 8 I. Introduction I. Introduction

11 9 In the debate surrounding the use of nuclear power in Germany, the public and policymakers alike often argue that, while Germany uses nuclear power, the problem of the final safe disposal of the radioactive waste produced is not resolved. Is this argument justified? Is it really true to say that the final safe disposal of waste in Germany is not possible? Or can it be rightly claimed that the repository issue in Germany is resolved? This brochure addresses these questions, provides answers, and forms an objective basis for discussions on the further course of action to be taken with regard to the final disposal of high-level heat-generating waste (HLW). The brochure explains how the Gorleben salt dome came to be a possible repository candidate, looks at the current international situation and the international policies that are in place, details the findings of exploration work to date, explains what results are available from 40 years of repository research, and examines the line of action to take going forward. The current situation of final disposal in Germany The final disposal of radioactive waste is an important sociopolitical issue not only on account of the controversial debate surrounding the safe use of nuclear energy to generate electricity, but also particularly because the radioactive waste has to be disposed of safely for a very long time without causing any harm to humans or to the environment. A large quantity of the waste is already present today and is being stored safely aboveground at interim storage facilities. More waste will be added. This radioactive waste has to be disposed of in a repository. The Federal Government is responsible for the construction of such a permanent disposal facility. Action is thus needed on the part of policymakers. Accordingly, the government parties agreed the following in their coalition agreement on November 11, 2005: The CDU, CSU and SPD acknowledge Germany s responsibility for the safe final disposal of radioactive waste and will tackle this issue in a speedy and resultoriented manner. We intend to solve this question by the end of the current electoral period. Fig. 1: Geographical location of the Gorleben salt dome in Lower Saxony

12 10 I. Introduction Fig. 2: Aerial photo of the Gorleben site A solution has been found for the final disposal of non-heat-generating low and medium-level waste. In March 2007, the plan approval for the former Konrad iron ore mine near Salzgitter was finally endorsed by the Federal Administrative Court and cannot be appealed. The mine is now being converted into a repository, with plans to put it into operation in Exploration work on the final disposal of highlevel waste, in particular, has been underway at the Gorleben salt dome since 1979 (Fig. 1 and 2). The exploration work has been interrupted since October 1, 2000 as a result of a moratorium imposed. This moratorium was agreed between the Federal Government and the four main electric utility companies on June 14, 2000 as part of the plan to phase out nuclear power. The moratorium on exploration is still in place today due to the divergent positions of policymakers as to the further course of action to be taken. Final disposal situation in other countries There is an international consensus that the final disposal of high-level waste in a purpose-built mine in deep geological formations is the best option and, from a technical perspective, can be implemented safely today. Consequently, many countries other than Germany such as Finland, France, Sweden and the USA are promoting repository projects in deep geological formations. Responsibility under nuclear law for repositories in Germany According to the German Atomic Energy Act ( 9a), the Federal Government is responsible for the final disposal of radioactive waste in Germany. Within the Federal Government itself, the Federal

13 11 Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) and the Federal Office for Radiation Protection (BfS), a subordinate authority, are responsible for the siting, planning, plant-related research and development, exploration, construction, operation and decommissioning of repositories for radioactive waste. The Federal Ministry of Economics and Technology (BMWi) is responsible for the nuclear energy industry and repository-related applied basic research. The Federal Institute for Geosciences and Natural Resources (BGR), a subordinate authority of the BMWi, deals with the primary geoscientific questions surrounding the final disposal of radioactive waste. Up until 1986, the Federal Ministry of the Interior (BMI) was responsible for final disposal tasks which are now under the jurisdiction of the BMU. On the basis of discussions led since the 1960s, and following consultations with various teams of experts, the BMI drew up criteria for the final disposal of radioactive waste in 1983, and published these in the form of the Safety Criteria for the Final Disposal of Radioactive Waste in a Mine (BMI 1983). These criteria still apply today and were the basis for the Konrad mine being approved as a repository for low and medium-level waste. Radioactive waste 3 High-level waste: This waste accounts for approximately ten percent of forecast waste volumes (approximately 22,000 m 3 by 2040, BfS 2007) and contains approximately 99 percent of the total radioactivity. Spent fuel elements from reactors and vitrified waste from reprocessing make up the vast majority of this waste. The radioactive decay of the radionuclides the waste contains causes considerable quantities of heat to be released. The level of gas generated is far lower than in the case of low-level and medium-level waste. The different physicochemical properties of these two individual waste categories mean that different requirements have to be met to permanently dispose of these wastes in deep geological formations. For this reason, Germany follows the dual repository concept which involves the final disposal of the two types of waste in separate repositories in different host rock formations. In contrast to other countries where low-level and intermediate-level radioactive waste is finally disposed of close to the surface, all radioactive waste in Germany should be finally disposed of in deep geological formations. The German concept for safe final disposal does not provide for waste retrieval once the repository has been sealed. Radioactive waste has different properties and is divided into two specific categories in Germany: 3 Low and medium-level waste: This waste constitutes about 90 percent of forecast waste volumes (approximately 277,000 m 3 by 2040, BfS 2007) but only contains approximately one percent of the radioactivity of the overall radioactive waste. This waste is primarily waste from nuclear power plants and from research and medicine. The radioactive decay of such waste does not result in any noteworthy production of heat. However, large quantities of gas are produced when the waste is stored. A small percentage of the medium-level waste can be assigned to heat-generating waste (e. g. fuel element hulls, reprocessing structural elements).

14 12 II. Why should rock salt be used for the final disposal of high-level radioactive waste? II. Why should rock salt be used for the final disposal of high-level radioactive waste?

15 13 The German disposal concept, which was developed using results from scientific research, is based on the following two principles for the final disposal of radioactive waste: 3 All radioactive waste generated should be finally disposed of in Germany in deep geological formations. 3 The geological barrier plays the most important role in isolating the waste, i. e. the rock salt encapsulating the radioactive waste in the case of Gorleben. Over 100 years experience in industrial salt-mining, and more than 40 years of intensive research, have given rise to an extensive knowledge base in Germany of the properties of rock salt which are relevant for the final disposal of radioactive waste, and of the numerous salt formations to be found in the country (Fig. 3 and Annex 1). This can be elaborated as follows: 3 Experience in mining in rock salt formations proves that stable underground structures can be constructed here. Thanks to the favorable mechanical properties of rock salt, cavities can be created without any special support and maintained for decades. 3 Under natural stratification conditions, the permeability of the rock salt toward gases and liquids is extremely low. The saline solutions found today in the Gorleben salt dome are just as old as the rock salt that formed the salt dome (solution trapped during sedimentation) i. e. over 200 million years old. This is an indicator for the fact that rock salt can be regarded as practically impervious as a host rock. 3 Rock salt exhibits a high level of specific thermal conductivity. For this reason, rock salt is particularly well suited as a host rock for high-level waste since the heat can be dissipated to the surrounding rock far better than in the case of crystalline or argillaceous rock, for example. Due to its specific properties, rock salt is particularly favorable as a host rock for the final disposal of high-level waste in Germany. Germany has the necessary scientific experience and extensive mining knowledge for final waste disposal in rock salt. 3 Rock salt reacts to mechanical load with a slow, flowing movement that is known as creeping. This particular property of rock salt causes cavities in the rock to be self sealed. As a result, the necessary geological barrier function is guaranteed in a natural way over very long periods of time once the emplacement process is complete.

16 14 II. Why should rock salt be used for the final disposal of high-level radioactive waste? Fig. 3: Properties of potential host rocks in Germany which are relevant for repository concepts Property Rock salt Clay/ Crystalline rock argillaceous rock (e. g. granite) Thermal conductivity High Low Medium Permeability Practically impermeable Very low to low Very low (unfractured) to permeable (fractured) Strength Medium Low to medium High Deformation behavior Visco-plastic (creep) Plastic to brittle Brittle Stability of cavities Self-supporting Artificial reinforcement required High (unfractured) to low (highly fractured) In-situ stress Isotropic Anisotropic Anisotropic Dissolution behavior High Very low Very low Sorption behavior Very low Very high Medium to high Heat resistance High Low High Favorable property Average Unfavorable property

17 III. Gorleben repository project 15 III. Gorleben repository project

18 16 1. How was the Gorleben salt dome chosen? 1. How was the Gorleben salt dome chosen? In the debate surrounding the Gorleben salt dome, it is often claimed that the Gorleben site was purely selected for political reasons and that technical and scientific reasons did not play a role in the ultimate selection of the site. This is not true, however. If we take a look at the history of the selection procedure for the Gorleben salt dome, it is clear that the site was selected in a highly scientific and methodical process. The selection procedure followed by the Federal Government In the period between 1964 and 1976, the Federal Government initially embarked on a search for salt structures which would be suitable candidates for a repository, and later implemented a selection process for a repository site for radioactive waste when searching for a location for a radioactive waste management center (WMC reprocessing, fuel element production, conditioning and final disposal should be concentrated at one site). radioactive waste, in a study it presented in 1964 [Richter-Bernburg & Hofrichter 1964]. Numerous criteria were applied for selecting the salt structures and for the comparative analysis of their suitability for the final disposal of radioactive waste (Annex 2). Since extensive knowledge of the outer shape and interior composition of the salt structures was not available in 1963/64, and additional studies were not carried out, the choice of the seven salt structures suggested cannot be put down to a systematic analysis of all the salt deposits available underground (Annex 2). Onsite work was terminated in 1966 on account of problems purchasing sites, and following the rejection of the projects in the regions affected. Fig. 4: Location of the salt structures (red triangles) appraised by Richter-Bernburg & Hofrichter (1964) with regard to their suitability for the final disposal of radioactive waste The sites identified in these processes (Annex 2 to 4) were chosen on the basis of the experience and results of numerous scientific searches, with predefined criteria for selection and exclusion, which were carried out from the middle of the 1960s to the start of the 1970s Initiated by recommendations and research work conducted by the American National Academy of Sciences, the then Federal Institute of Soil Research (Bundesanstalt für Bodenforschung) and the German Nuclear Energy Commission already voiced support for the final disposal of radioactive waste in salt deposits deep underground at the start of the 1960s. In 1963, the Federal Institute of Soil Research presented a report which underlined the particular suitability of salt formations as repositories, and contained an initial synopsis of the knowledge then available regarding salt structures in Germany [Martini 1963]. 6 Following an order from the then Federal Ministry for Scientific Research (BMwF) issued on December 12, 1963, the Federal Institute of Soil Research named seven salt structures (Fig. 4), which were considered suitable sites to mine caverns for the final disposal of 1. Heide, 2. Geesthacht, 3. Harsefeld, 4. Bunde/Jemgum, 5. Krummendeich, 6. Leutesheim, 7. Bremen-Lesum; yellow circles location of nuclear reactors

19 17 In 1973, the then Federal Ministry for Research and Technology (BMFT) commissioned the nuclear fuel reprocessing company KEWA to identify sites for a radioactive waste management center. This search focused on finding a site that would guarantee the environmentally friendly operation of surface facilities for the reprocessing and conditioning of radioactive waste. The repository was merely an additional requirement here. Precisely this element was reflected in the site selection criteria which formed the basis for the dual phase selection process. Comprehensive selection criteria (Annex 3) were applied in Phase 1 (overview investigations) and Phase 2 (regional investigations and interim site appraisals) of the Federal Government selection process known as the KEWA study. Taking geological expert reports into account, this study gave the sites at Ahlden (Lichtenhorst salt dome), Börger (Wahn salt dome) and Fassberg (Weesen-Lutterloh salt dome) the best rating (Fig. 5). Geological exploration work which the Federal Government commenced at these three sites in 1975 was suspended in August 1976 on account of local protests and not for technical or scientific reasons. Fig. 5: Areal distribution of the sites examined in greater detail with regard to their suitability as a radioactive waste management center as part of the Federal Government site selection process (KEWA study) (red triangles = sites) In the course of two multiphase selection processes, the Federal Government looked for salt structures for the purpose of final waste disposal and for a site for an WMC including a repository. Geological exploration work at the sites mentioned was suspended in 1966 and 1976 on account of protests from some of the local population. The selection process of the Land of Lower Saxony 1. Ahlden Lichtenhorst salt dome, 2. Börger Wahn salt dome, 3. Faßberg Weesen-Lutterloh salt dome, 4. Friedrichskoog (Schleswig-Holstein, coastal location), 5. Karlsruhe (reprocessing plant), 6. Lütau Juliusburg salt dome, 7. Uchte (sparsely populated, near Loccum), 8. Mahlberg tertiary potash deposits Oberrheintalgraben, 9. Sohlhöhe (Spessart), 10. Oberwesel (Southwestern Rhenish Massif); yellow circles location of nuclear reactors When the KEWA investigations and studies did not yield the desired result in 1976, Lower Saxony implemented a selection process for an WMC [see Tiggemann 2004]. The Land government of Lower Saxony deployed an interministerial task force (IMAK) for this purpose. In contrast to the procedure followed by the Federal Government, this process applied a far more extensive catalogue of criteria. The sites proposed in the KEWA studies were included. Despite initial strategic reservations, sites close to the border with the former GDR such as the Gorleben salt dome were no longer ruled out. 140 salt domes were considered in total. The selection process consisted of four specific phases (Annex 4). In the fourth phase, the four remaining sites the salt domes at Wahn, Lichtenhorst, Gorleben and Mariaglück/Höfer were subject to further intensive technical investigations and discussion (Fig. 6). The results identified the Gorleben salt dome as the most favorable candidate. The Federal Government, however, had reservations on account of Gorleben s proximity to the border with the GDR. In the cabinet bill for

20 18 1. How was the Gorleben salt dome chosen? the Land government, no preference was initially made with regard to the two best sites at Gorleben and Lichtenhorst. The bill merely recommended that only one of the two sites be explored. In February 1977, the cabinet of Lower Saxony finally chose Gorleben since this site best met all the selection criteria. The political reservations of the Federal Government were not considered to be of a serious nature. The Federal Government accepted the Gorleben site as the preliminary choice for the radioactive waste management center (WMC) on July 5, While the WMC project in Gorleben was the subject of disputes and protests, which were primarily directed at the reprocessing plants, it also received continuous support with regard to the creation of jobs in the economically less developed border area. The Gorleben Commission was founded in 1977 as a discussion platform for the region. On the initiative of the Land government of Lower Saxony, a public symposium known as the Gorleben hearing was held between March 28 and April 3, 1979 and was attended by many international participants. In his policy statement on May 16, 1979, Minister-President Dr. Albrecht recommended not building the reprocessing plant as part of the WMC but did recommend all parties remain committed to the Gorleben repository project. Government leaders from the Federal Government and Länder established a State Secretaries Committee for Disposal on July 6, In their official decision on September 28, 1979, they welcomed the willingness of the Land government of Lower Saxony to allow the construction of a repository in Gorleben as soon as the exploration work and mining-specific development of the salt dome find that this is a suitable site for a repository. For this reason, we will push ahead with exploration work and the mining-specific development of the Gorleben salt dome without delay [BMI 1981]. In line with the procedure at that time applied for the development of large-scale industrial projects, as soon as the site had been announced, the public was included in the processes and steps were taken, which also provided for hearings for the parties involved. In retrospect, it can be said that the Gorleben project was revolutionary in terms of the steps it took when communicating with the public, particularly by establishing the Gorleben Commission in 1977 and holding the international Gorleben hearing in the spring of Fig. 6: Location of the sites examined in greater detail with regard to their suitability as a radioactive waste management center as part of the site selection process conducted by the Land of Lower Saxony 1. Börger Wahn salt dome 2. Ahlden Lichtenhorst salt dome 3. Gorleben salt dome 4. Mariaglück mine Höfer salt dome; Blue = salt structures found in North Germany