Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-30158 Beitrag zu einem Tagungsband Zencker, Uwe; Wieser, Günter; Qiao, Linan; Protz, Christian Modeling strategies for dynamic finite element cask analyses The safety of transport packages may be demonstrated by numerical calculation of load scenarios defined in the IAEA regulations. Possible handling accidents of casks at interim storage sites or in a final repository are typically analyzed by dynamic finite element computations. In each case the investigated load scenario must be transferred into a mathematical model. Secondly the mathematical model must be transferred into a numerical model. Reliable finite element models should be developed by assembling verified sub-models of components. The finite element mesh, material modeling, initial and boundary conditions, contact definitions, and time integration as well as the benefit of pre- and post-calculations are discussed. The paper presents lessons learnt from modeling dynamic test scenarios for finite element analyses over the years. Omnipress Institute of Nuclear Materials Management (INMM) 2013 PATRAM 2013 - 17th International symposium on the packaging and transportation of radioactive materials (Proceedings) PATRAM 2013 - 17th International symposium on the packaging and transportation of radioactive materials San Francisco, CA, USA 18.08.2013 23.08.2013 Session A, Paper 280, 1 10 2016-02-20 OPUS4-19396 Beitrag zu einem Tagungsband Zencker, Uwe; Weber, Mike; Qiao, Linan; Menzel, Martin; Droste, Bernhard Beurteilungsmethoden für Transport- und Lagerbehälter mit erhöhten metallischen Reststoffanteilen - Behälterbruchsicherheitsuntersuchungen und Entwicklung eines KONRAD-Referenzprüfstandfundamentes Hamburg KONTEC Gesellschaft für technische Kommunikation mbH 2009 9. Internationales Symposium "Konditionierung radioaktiver Betriebs- und Stilllegungsabfälle" (KONTEC 2009) - Proceedings 9. Internationales Symposium "Konditionierung radioaktiver Betriebs- und Stilllegungsabfälle" (KONTEC 2009) Dresden 2009-04-15 2009-04-17 646 652 2016-02-19 OPUS4-23844 Beitrag zu einem Tagungsband Zencker, Uwe; Weber, Mike; Qiao, Linan; Droste, Bernhard; Völzke, Holger Mechanical safety analyses of cast iron containers for the KONRAD repository Within the last years BAM has carried out numerous drop tests with prototype casks made of ductile cast iron onto targets according to the requirements for final disposal of non-heat generating waste in the German KONRAD repository. The results have shown that the target specifications in the acceptance criteria have to be defined more accurately to get reproducible test results with high precision. Hence, a suitable test stand foundation was developed with much effort. The integrity of the upper concrete layer of this target must be preserved during a test. Recently the geometrical properties of a tested cubic cast iron container led to a concentration of the impact forces beneath the container walls. The target was damaged strongly with the consequence of inadmissible reduction of cask stresses. For that reason the target construction was modified. However, the basic design was not changed. A prefabricated concrete slab was still joined by a mortar layer to the IAEA target of the BAM drop test facility. In the course of the optimization of the test stand foundation the concrete slab dimensions and the reinforcement were enlarged. During the drop test repetition the target kept intact. Additionally, the mechanical behavior of the cast iron container and the target was analyzed by finite element calculations. This improved target construction is suggested as a reference target for drop tests with casks whose mass and base area are covered by the container types VI or VII respectively according to the KONRAD repository acceptance criteria. The measurements during the drop tests with cast iron casks have provided the strains on the cask surface at selected positions. This allows the verification of finite element simulations of drop tests which show the stress distribution also inside the component. In September 2008 a drop test was carried out with a cylindrical cast iron cask containing an artificial material defect which was designed under consideration of critical stress states in the cask body. This drop test could demonstrate the safety against failure by fracture of a cask made of a special cast iron with reduced fracture toughness. PATRAM 2010 PATRAM 2010 - 16th International symposium on the packaging and transport of radioactive materials (Proceedings) PATRAM 2010 - 16th International symposium on the packaging and transport of radioactive materials London, UK 2010-10-03 2010-10-08 1 8 (Session T28 / Paper 220) 2016-02-19 OPUS4-18399 Beitrag zu einem Tagungsband Zencker, Uwe; Qiao, Linan; Weber, Mike; Kovacs, Oliver; Droste, Bernhard Application limits of low-ductile cast iron for radioactive waste containers Institute of Nuclear Materials Management 2007 PATRAM 2007 - 15th International symposium on the packaging and transportation of radioactive materials (Proceedings) PATRAM 2007, 15th International Symposium on the Packaging and Transportation of Radioactive Materials Miami, Florida, USA 2007-10-21 2007-10-26 Session B, Paper #97 1 8 2016-02-19 OPUS4-14712 Beitrag zu einem Tagungsband Zencker, Uwe; Qiao, Linan; Weber, Mike; Kovacs, Oliver; Droste, Bernhard Sicherheitstechnische Analyse von Transport- und Lagerbehältern aus Gusseisen mit erhöhten metallischen Reststoffanteilen mittels Fallversuchen Dresden Gesellschaft für technische Kommunikation mbH / Kerntechnische Gesellschaft 2007 Tagungsband KONTEC 2007 KONTEC 2007 Dresden, Deutschland 2007-03-21 2007-03-23 869 875 2016-02-19 OPUS4-34937 Beitrag zu einem Tagungsband Zencker, Uwe; Qiao, Linan; Völzke, Holger Dynamic finite element analysis of cask handling accidents at storage sites The safety assessment of casks for radioactive material at interim storage facilities or in final repositories includes the investigation of possible handling accidents if clearly defined test conditions are not available from the regulations. Specific handling accidents usually are the drop of a cask onto the transport vehicle or the floor as well as the collision with the wall of the storage building or another cask. For such load cases an experimental demonstration of cask safety would be difficult. Therefore, numerical analyses of the entire load scenario are preferred. The lessons learnt from dynamic finite element analyses of accident scenarios with thick-walled cubical containers or cylindrical casks are presented. The dependency of calculation results on initial and boundary conditions, material models, and contact conditions is discussed. Parameter sets used should be verified by numerical simulation of experimentally investigated similar test scenarios. On the other hand, decisions have to be made whether a parameter or property is modeled in a realistic or conservative manner. For example, a very small variation of the initial impact angle of a container can cause significantly different stresses and strains. In sophisticated cases an investigation of simpler limit load scenarios could be advantageous instead of analyzing a very complicated load scenario. 2015 ASME 2015 Pressure vessels & piping conference - PVP2015 (Proceedings) 978-0-7918-5702-1 ASME 2015 Pressure vessels & piping conference - PVP2015 Boston, Massachusetts, USA 19.07.2015 23.07.2015 Paper 45606, 1 10 2016-02-20 OPUS4-34938 Beitrag zu einem Tagungsband Zencker, Uwe; Qiao, Linan; Völzke, Holger Strategies for numerical modelling of metal gaskets in transport and storage casks Metal gaskets in the lid system of transport and storage casks for radioactive material have to guarantee leak-tightness and safe enclosure of the radioactive inventory under normal and accident conditions during transport, in case of accidents and for the longterm interim storage. For safety assessments by nurnerical simulation of the thermomechanical behaviour of a lid system with metal gaskets, the finite element method offers three options to use: i) special gasket elements, ii) complex three-dimensional modeHing with solid elements, and iii) a simplified axisymmetric approach. Gasket elements can be adjusted by many parameters, but they give only a global representation of the experimentally observed gasket behaviour. For calculations of the entire cask including the lid system with gaskets, nonetheless this approach is recommended. To investigate the hardly measurable impact behaviour in detail or to extrapolate the long-term behaviour, a local modeHing of all parts of a gasket and their interactions with effects like elastic-plastic deformation, creep, relaxation, and friction is necessary. The three-dimensional model can describe the change of contact area between outer jacket of the gasket and flange dependent on the load conditions, what overcomes an essential limitation of special gasket elements. To simplify the problern of investigating the underlying physical effects, an axisymmetric lid system can be modelled with axisymmetric finite elements. Usually an approximation is only necessary for the helical spring of a metal gasket. This paper explains basic ideas for an adequate finite element simulation of cask lid systems with metal gaskets and their thermo-mechanical behaviour under specific load scenarios. Nuclear institute (ni) 2015 RAMTRANSPORT 2015 - International conference on the radioactive materials transport and storage (Proceedings) RAMTRANSPORT 2015 - International conference on the radioactive materials transport and storage Oxford, UK 19.05.2015 21.05.2015 Paper RAM15-27, 1-9 2016-02-20 OPUS4-48914 Beitrag zu einem Tagungsband Zencker, Uwe; Qiao, Linan; Völzke, Holger Fracture mechanical analysis of a cylindrical cast iron cask The safety evaluation of cask components made of ductile cast iron includes investigations to prevent brittle fracture. Generally, ductile cast iron is endangered by brittle fracture especially at low temperatures (down to -40°C) and in combination with existing crack-like material defects. An applicable method is the assessment of fracture resistance using fracture mechanics according to the IAEA guidelines. The approach is based on the prevention of fracture initiation. For application of these principles for drop loads, account must be taken both of dynamic stresses within the component and dynamic material behavior. Basically, the dynamic stress intensity factor of postulated pre-existing crack-like defects is compared with the dynamic fracture toughness of the material. Applicable numerical and experimental methods for the safety assessment of cask components are demonstrated for the case of an artificially pre-cracked cylindrical cast iron cask which undergoes dynamic loading conditions as result of the hard impact between the cask and a concrete target. The proposed evaluation procedure is a combination of numerical and experimental steps. Exemplarily, the calculated stress intensity factor is compared with measured fracture toughness values from single edge notched bending specimens. 2019 Proceedings of the 19th International Symposium on the Packaging and Transportation of Radioactive Materials (PATRAM 2019) 19th International Symposium on the Packaging and Transportation of Radioactive Materials (PATRAM 2019) New Orleans, LA, USA 04.08.2019 09.08.2019 Paper 1209, 1 7 2019-09-11 OPUS4-43631 Beitrag zu einem Tagungsband Zencker, Uwe; Qiao, Linan; Völzke, Holger Influence of impact angle and real target properties on drop test results of cubic containers Drop test scenarios with cubic containers without impact limiters at interim storage sites or in a final repository have been investigated by numerical simulations. An ideally flat drop is impossible to conduct as a free fall of a container even under laboratory conditions. Dynamic stresses and strains inside the container structure are sensitive to the impact angle. Even very small impact angles cause remarkable changes in the experimental or numerical results when a flat bottom or wall of a container hits a flat target. For drop tests with transport packages the International Atomic Energy Agency (IAEA) regulations define an essentially unyielding target. In contrast, potential accident scenarios for storage containers are derived from site-specific safety analyses or acceptance criteria in Germany. Each interim storage site or repository has a yielding or so-called real target with individual structural and material properties. The real target acts as a kind of impact limiter. A more conservative container design is required if the impact limiting effect of the target is not considered. The Mechanical Society of Mechanical Engineers (ASME) 2017 Proc. ASME 2017 Pressure Vessels and Piping Conference 7 978-0-7918-5802-8 ASME 2017 Pressure Vessels and Piping Conference Waikoloa, Hawaii, USA 16.07.2017 20.07.2017 Article UNSP V007T07A039, 1 9 10.1115/PVP2017-65731 2018-01-09 OPUS4-28529 Beitrag zu einem Tagungsband Zencker, Uwe; Qiao, Linan; Kasparek, Eva Maria; Völzke, Holger Modeling of cylindrical casks under horizontal drop test conditions Cylindrical casks made of ductile cast iron are used for transport, interim storage and final disposal of radioactive waste in Germany. A basic design criterion is the ability to withstand a horizontal drop without impact Binders onto a foundation representative for the real ground of a storage facility. The increasing use of more cost-effective material compositions requires optimized cask geometries to reduce stresses and strains in the cask structure. For example, a non-uniform wall thickness was introduced to reduce maximum wall bending stresses. As a result, the load characteristics changed from line load to point load at bottom and lid side under horizontal drop fest conditions. Hereby, the position of highest stress inside the structure has shifted significantly. This was the reason for a systematic investigation of effects caused by small design changes or small variations of fest conditions. It led to a better understanding of the positions of high local stresses, their time history and maximum value for cylindrical casks under horizontal drop test conditions. Hence, the paper presents the lessons learnt from modeling and simulating such scenarios considering an impact without limiters onto a realistic target. Omnipress American nuclear society (ANS) 2013 IHLRWM 2013 - 14th International high-level radioactive waste management conference (Proceedings) 978-1-62748-644-6 14th International high-level radioactive waste management conference Albuquerque, New Mexico, USA 28.04.2013 02.05.2013 1114 1119 (Paper # 6862) 2016-02-20