TY - CONF A1 - Völzke, Holger A1 - Wolff, Dietmar A1 - Zencker, Uwe A1 - Orellana Pérez, Teresa T1 - Ongoing R&D work at BAM N2 - The presentation provides an update on the German nuclear waste management policy towards final disposal and related reasearch at BAM. Topics include long term investigations of metal seals, investigations of fuel cladding failure mechanisms, and the development of requirements and concepts for high level radioactive waste and spent fuel disposal containers. T2 - EPRI Extended Storage Collaboration Program (ESCP) International Subcommittee Meeting 2018 CY - Munich, Germany DA - 05.06.2018 KW - Radioactive waste KW - Metal seal KW - Disposal container KW - Fuel cladding PY - 2018 AN - OPUS4-45328 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Völzke, Holger T1 - Perspectives on extending interim storage of spent nuclear fuel (beyond the initial license period) N2 - The presentation adddresses the consequences and challenges of the German nuclear phase-out in conjunction with the restart of siting process for a high-level radioactive waste repository. Concerning spent fuel this will lead to extended interim storage periods for the dry storage casks beyond the initial licensing period of 40 years. For extending storage periods additional safety assessments and data about the long term performance of materials, components and casks will be needed and BAM has already been lauching specific R&D projects addressing identified data gaps. T2 - 8th Annual Nuclear Decommissioning Conference Europe CY - Manchester, UK DA - 24.05.2017 KW - Spent Fuel KW - Storage KW - Disposal PY - 2017 AN - OPUS4-40358 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Völzke, Holger T1 - Preserving competence in nuclear technology - BAM's contributions N2 - With regard to the nuclear phase-out in Germany preserving competence in nuclear technology is a major challenge. This presentation explains how BAM addresses this issue within its specific tasks, expertise and long term experience on nuclear waste package design testing and safety evaluation. T2 - 48th Annual Meeting on Nuclear Technology (AMNT 2017) CY - Berlin, Germany DA - 16.05.2017 KW - Nuclear Technology KW - Safety KW - Waste Packages KW - Design Testing PY - 2017 AN - OPUS4-40306 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Völzke, Holger A1 - Wolff, Dietmar T1 - Spent Nuclear Fuel and HLW Storage towards Disposal - Challenges and Perspectives of an Integrated Approach - N2 - This paper describes and discusses the major challenges of spent fuel management in Germany after the phase-out of nuclear electricity generation was decided in 2011 and a new repository siting procedure was implemented in 2013. Consequences from those decisions which were legally founded by amendments of the German Atomic Energy Act (AtG) result in the need to transfer all remaining spent fuel from limited reactor operation (last reactor shutdown until the end of 2022) into casks for subsequent dry interim storage on-site. Storage licenses are generally issued site-specific considering specific dual purpose casks (DPC) and their inventories and they are generally limited to 40 years so far. But the need for extending the interim storage period in the future has become obvious. Even though, this may not be an issue to be solved already today questions about additional safety demonstrations will arise as soon as licenses need to be extended. Certainly, these questions will ask for reliable data about the long term performance and safety of structures, systems, and components, e. g. the long term performance of cask components and materials like bolted closure systems including metal seals, or fuel rod behaviour concerning cladding materials under stress and temperature conditions. In case of dual purpose casks for storage and transportation this includes aspects on how to demonstrate transportability during or after several decades of interim storage. Long term investigations often require plenty of time and therefore need to be initiated timely. T2 - PATRAM 2016 The 18th International Symposium on the Packaging and Transportation of Radioactive Materials CY - Kobe, Japan DA - 18.09.2016 KW - Storage KW - Spent Fuel KW - Disposal PY - 2016 AN - OPUS4-40301 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Völzke, Holger A1 - Wolff, Dietmar ED - Saegusa, T. ED - Sert, G. ED - Völzke, Holger ED - Wille, Frank T1 - Long-term metal seal performance T2 - Basic of Transport and Storage of Radioactive Materials N2 - For the long-term storage of spent nuclear fuel and other high-Level radioactive waste, dual purpose casks for the transportation and storage are widely used. Usually, these casks consist of a thick-walled monolithic cask body and a bolted double barrier lid System equipped with metal seals (consisting of an inner helical spring and two outer metal layers with a total cross-section diameter between 5 and 10 mm) to ensure the long-term safe confinement of the radioactive inventory. Based on analytical and experimental studies, such metallic Systems have been qualified of storage periods of up to four decades so far as long as proper manufacturing and assembling conditions are met. More than 20 years of Operation experience with a permanently increasing number of casks has shown full compliance with the expectations. In the meantime many countries have to face a significant delay of establishing a high-level radioactive waste repository what leads to Need for extending interim storage periods for probably 60, 80 or 100 years. For that reason the long-term performance of metal seals for such time periods is of specific internst to demonstrate their sufficient safety function and specific investigations have already been launched, e.g. by BAM, to gain more experimental data and to develop validated models to extrapolate the seal performance to longer periods of time and or requested temperature levels. KW - Metal Seal KW - Container KW - Safety KW - radioactive waste PY - 2018 SN - 978-981-3234-03-1 SP - Chapter 20, 293 EP - 303 PB - World Scientific CY - Singapore AN - OPUS4-47669 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zencker, Uwe A1 - Völzke, Holger T1 - Brittle Failure Limits of Spent Fuel Claddings Subjected to Long-Term Dry Interim Storage Conditions T2 - Proceedings of the IAEA International Conference on the Management of Spent Fuel from Nuclear Power Plants - Meeting the Moment N2 - The mechanical properties of spent fuel claddings can be adversely affected under the conditions of long-term dry interim storage, so that the failure limits may be reached in case of mechanical loads during handling or transport after storage. Pre-storage drying and the early stage of interim storage can expose the cladding to higher temperatures and higher tensile hoop stresses than those associated with in-reactor operation and pool storage. During slow cooling of a cladding tube under internal pressure, radial hydrides may precipitate in zirconium-based cladding alloys. This can lead to embrittlement of the material and sudden failure of the cladding integrity under mechanical stress. In order to prevent brittle failure, numerical methods are being developed to predict the mechanical behaviour and identify limiting conditions. Experimental investigations, numerical analyses and evaluation methods are discussed. An established experimental method for characterising cladding materials is the Ring Compression Test (RCT). Some test results on irradiated cladding tubes after operation in pressure water reactors are publicly available. However, it is helpful to carry out studies on unirradiated surrogate claddings with similar material properties to reduce the effort associated with irradiated samples in hot cells and to perform material tests with a wider range of parameters. On the basis of such experimental data, load-displacement curves have been numerically analysed for a selection of cladding materials. Radial hydrides can cause a sample to break suddenly due to fracture even at low deformation. Noticeable load drops in the RCT are caused by unstable crack propagation through the radial hydride network. The failure mechanism is quasi-cleavage in the hydrides and micro-void nucleation, growth, and coalescence in the zirconium matrix, with ductile tearing patches connecting adjacent hydrides. The cohesive zone approach was used to simulate the failure process taking into account the radial hydride morphology. The developed method can adequately describe both the deformation and failure behaviour of irradiated as well as unirradiated claddings of zirconium-based alloys with radial hydrides under RCT conditions. Limiting conditions can be expressed in terms of fracture energy and cohesive strength. T2 - IAEA International Conference on the Management of Spent Fuel from Nuclear Power Plants - Meeting the Moment CY - Vienna, Austria DA - 10.06.2024 KW - Ageing Management KW - Cladding Embrittlement KW - Extended Storage KW - Ring Compression Test KW - Spent Nuclear Fuel PY - 2024 SP - 1 EP - 10 AN - OPUS4-60323 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -