Technical Report NTB 09-06
The Nagra Research, Development and Demonstration (RD&D) Plan for the Disposal of Radioactive Waste in Switzerland
Nagra's mission is to develop safe geological repositories in Switzerland for all radioactive wastes arising in Switzerland. Two types of repositories are foreseen, one for low and intermediate level waste (L/ILW) and one for spent fuel, vitrified high level waste and longlived ILW (SF/HLW/ILW). Repository implementation involves a stepwise process that takes several decades, thus a comprehensive planning base for the scientific and engineering work is needed, which is presented in the RD&D (research, development and demonstration) plan. The main objective of the RD&D Plan is to establish the purpose, scope, nature and timing of various future RD&D activities, starting from the various requirements and planning assumptions.
Chapter 1 presents the overall objectives of the report and a brief history of the steps leading to the present situation. The planning of work is conditioned by the Federal Government decision in 2006 that Nagra had successfully shown in Project Entsorgungsnachweis (disposal feasibility) that safe disposal of SF/HLW/ILW in Switzerland is technically feasible. Earlier studies and safety authority reviews had already in 1988 lead to the Federal Government decision on the overall feasibility of safe disposal of L/ILW. Following the Project Entsorgungsnachweis decision, the Federal Government initiated the Sectoral Plan for Geological Repositories, which elaborates the siting process. The Sectoral Plan provides a framework within which specific objectives must be met for selecting suitable sites for disposal of both L/ILW and SF/HLW/ILW for which general licence applications are to be made. The overall planning is based on the status as of Nagra’s submission of proposals for Stage 1 of the Sectoral Plan, which should result in the selection of geologically suitable siting regions.
Chapter 2 presents the overall planning premises for implementation of repositories for L/ILW and SF/HLW/ILW including the assumed schedule, the waste types and quantities and the safety strategy for the repositories. The time plan is presented, which includes the Sectoral Plan and general licence procedure, construction and operation of Underground Research Laboratories (URLs) at the sites, construction licence procedure and the operating licence procedure. It is expected that emplacement of L/ILW could begin in about 2035, whereas SF/HLW emplacement would begin about 2050. Waste emplacement is followed by a monitoring period (planning assumption of 50 years), at the end of which an application would be made for closure. The various waste types and quantities produced by nuclear power plants and medicine, industry and research are summarised and the safety concepts for the two repositories are illustrated.
Chapter 3 discusses the RD&D planning process and methodology and the various categories of requirements that dictate the nature and timing of the programme and the planned RD&D. These include legal, regulatory and policy requirements; waste producer requirements; authorities’ recommendations; public expectations; and technology and safety requirements. Together these frame the issues that must be addressed in the programme and establish the nature and timing of the various elements of technical and scientific work.
Chapter 4 summarizes the RD&D issues for SF/HLW identified by Nagra in Project Entsorgungsnachweis and the recommendations made in the formal reviews of the project that were requested by the Federal Government. The broad areas of work required for development of a L/ILW repository are also identified. The status of development of the various categories of technology required for repository implementation is discussed in the context of worldwide progress in the various technology development areas.
Chapter 5 elaborates the strategic requirements for developing the two types of repositories. The definition of the waste types, their properties and the legal and regulatory requirements for disposal set the framework for the timing of implementation as well as for the repository concepts needed to safely dispose of the waste. In the repository concepts long-term safety must be provided by multiple passive safety barriers with a balanced contribution from the engineered and geological systems. The repository design concepts include: i) the main facility, where wastes will be disposed of and which will be backfilled and sealed in due time after waste emplacement; ii) the test zones, where site-specific data for the safety-relevant properties of the host rock are acquired to confirm the safety and technical feasibility; iii) the pilot facility, where the behaviour of waste, backfill material and host rock is monitored until the end of the monitoring period and in which data is collected to confirm safety with a view to closure. Host rocks with favourable properties must be selected within stable large-scale geologic-tectonic situations, which ensure a significant contribution of the geological barrier to the safety functions.
The Sectoral Plan process is discussed in some detail in order to explain the requirements on Nagra’s RD&D programme for each of the stages of site selection up to the general licence application. For Stage 1, the selection of geologically suitable regions, the steps are outlined that led to the proposal of the six geological siting regions for the L/ILW repository (Südranden, Zürcher Weinland, Nördlich Lägeren, Bözberg, Jura-Südfuss, Wellenberg) and the three geological siting regions for the HLW repository (Zürcher Weinland, Nördlich Lägeren, Bözberg). Stage 2 requires the selection of at least two sites for L/ILW and HLW repositories, which is followed by Stage 3, with the selection of one site for each repository, which would provide the basis for the general licence application. The specificity of the requirements of the Sectoral Plan combined with the results of the prior work programme lead to a rather clear definition of the RD&D activities and the main expected reports for each of the stages up to the general licence application.
For the subsequent stages of repository implementation, i.e. construction and operation of a rock laboratory at the chosen site, construction of the repository and operation of the repository until final closure, the broad nature of the work is defined. This permits the level of maturity of the science and technology for each stage to be identified, such that the RD&D studies are appropriately timed and resources are effectively managed.
Chapter 6 gives an overview of the RD&D work to be done in the next 5 to 10 years, i.e. the time frame up to the general licence application, including the objectives, status and principal focus in the various areas, including:
- geological investigations (compliance with requirements for properties and geometry of host rocks and confining units and for long-term geological evolution; data for key safetyrelevant parameters)
- safety assessment (compliance with requirements for operational and long-term safety)
- radioactive waste and materials (compliance with requirements for waste)
- repository engineering concepts, including concepts for waste retrievability and monitoring. This includes also the concepts for the engineered barrier system and their performance (compliance with requirements for repository design).