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 OPUS4-37046 Beitrag zu einem Tagungsband Weber, Mike; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar; Zencker, Uwe; Völzke, Holger; Schulze, Dietmar Testing and numerical simulation of elastomeric seals under consideration of time dependent effects Due to delays in the siting procedure to establish a deep geological repository for spent nuclear fuel and high level waste and in construction of the already licensed Konrad repository for low and intermediate level waste, extended periods of interim storage will become more relevant in Germany. BAM is involved in most of the cask licensing procedures and is responsible for the evaluation of cask-related long-term safety issues. Elastomeric seals are widely used as barrier seals for containers for low and intermediate level radioactive waste. In addition they are also used as auxiliary seals in spent fuel storage and transportation casks (dual purpose casks (DPC)). To address the complex requirements resulting from the described applications, BAM has initiated several test programs for investigating the behavior of elastomeric seals. These include experiments concerning the hyperelastic and viscoelastic behavior at different temperatures and strain rates, the low temperature performance down to -40°C, the influence of gamma irradiation and the aging behavior. The first part of the paper gives an overview of these tests, their relevant results and their possible impact on BAM's work as a consultant in the framework of approval and licensing procedures. The second part presents an approach of the development of a finite element model using the finite element code ABAQUS®. The long-term goal is to simulate the complex elastomeric behavior in a complete lid closure system under specific operation and accident conditions. American society of mechanical engineers (ASME) 2016 Proceedings-CD, ASME 2016 Pressure Vessels & Piping Conference (PVP2016) 7 978-0-7918-5045-9 ASME 2016 Pressure Vessels & Piping Conference (PVP2016) Vancouver, BC, Canada 17.07.2016 21.07.2016 Paper 63192, 1 10 2016-08-03 OPUS4-33832 Beitrag zu einem Tagungsband Weber, Mike; Zencker, Uwe; Wolff, Dietmar; Jaunich, Matthias; Kömmling, Anja; Völzke, Holger; Schulze, Dietmar Numerical simulation of the behaviour of elastomer seals under consideration of time dependent effects Due to delays in the site-selection procedure to establish a deep geological repository for spent nuclear fuel and high level waste and in construction of the already licensed Konrad-repository for low and intermediate level waste without heat generation, extended periods of interim storage become more relevant in Germany. BAM is involved in most of the cask licensing procedures and especially responsible for the evaluation of cask-related long-term safety issues. The long-term performance of elastomer seals for lid Systems of transport and storage casks whether used as auxiliary seals in spent fuel caslcs or as primary seals for low and intermediate level waste packages is an important issue in this context (Jaunich, 2013; Jaunich, 2014; Kömmling, 2015). The polymeric structure of these seals causes a complex mechanical behaviour with time-dependent elasticity reduction and loss of elastic recovery. The paper presents first results of a comprehensive test Programme consisting of several static and dynamic mechanical short- and long-term tests which have been carried out at BAM on specimens made of representative types of elastomers, fluorocarbon rubber (FKM) and ethylene propylene diene rubber (EPDM). The investigation of the test results used to identify material models and their Parameters as well as the development of two finite element models for the numerical Simulation of tension and compression tests using the finite element code ABAQUS® are described. The calculation results are presented in comparison to the test results. The influence of important material and test parameters was investigated and discussed in sensitivity analyses. 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 Session 4, Paper 28, 1 9 2016-02-20 OPUS4-41841 Beitrag zu einem Tagungsband Weber, Mike; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar; Zencker, Uwe; Völzke, Holger; Schulze, Dietmar; Probst, Ulrich Testing and Numerical Simulation of Elastomers - From Specimen Tests to Simulation of Seal Behavior under Assembly Conditions Due to delays in the siting procedure to establish a deep geological repository for spent nuclear fuel and high level radioactive waste as well as in construction of the already licensed Konrad repository for low and intermediate level radioactive waste, extended periods of interim storage become more relevant in Germany. BAM is involved in most of the cask licensing procedures and especially responsible for the evaluation of cask-related long-term safety issues. The long-term performance of elastomer seals for lid systems of transport and storage casks, whether used as auxiliary seals in spent fuel casks or as primary seals for low and intermediate level waste packages, is an important issue in this context. The polymeric structure of these seals causes a complex mechanical behavior with time-dependent sealing force reduction. The results of a comprehensive purpose-designed test program consisting of basic compression and tension tests as well as relaxation tests on unaged specimens of representative types of elastomers (fluorocarbon rubber (FKM) and ethylene propylene diene rubber (EPDM)) at different temperatures and strain rates are presented. They were used to identify the constitutive behavior and to obtain parameters for finite element material models provided by the computer code ABAQUS®. After estimating the influence of uncertainties such as Poisson's ratio and friction coefficient by sensitivity analyses, the chosen parameters had to prove their suitability for the finite element simulation of the specimen tests themselves. Based on this preliminary work the simulation of a specific laboratory test configuration containing a typical elastomer seal with circular cross section is presented. The chosen finite element material model and the implemented parameters had to show that they are able to represent not only the specimen behavior under predominantly uniaxial load but also the more complex stress states in real components. Deviations between the measured and calculated results are pointed out and discussed. For the consideration of long-term effects in the simulation of elastomer behavior, test results of aged specimens are needed. First information about a new test program, started recently and planned to provide these data, are given. American society of mechanical engineers (ASME) 2017 Proceedings-CD, ASME 2017 Pressure Vessels & Piping Conference (PVP2017) 7 978-0-7918-5802-8 ASME 2017 Pressure Vessels & Piping Conference (PVP2017) Waikoloa, Hawaii, USA 16.07.2017 20.07.2017 Article UNSP V007T07A035, 1 8 2017-09-06 OPUS4-7414 Zeitschriftenartikel Wolff, Dietmar; Probst, Ulrich; Völzke, Holger; Droste, Bernhard; Rödel, Roland Safety aspects of long-term dry interim storage of type-B spent fuel and HLW transport casks Ashford Ramtrans Publ. 2004 Packaging, transport, storage & security of radioactive materials (RAMTRANS) 15 3-4 207 213 2016-02-19 OPUS4-11310 Vortrag Wolff, Dietmar Well defined liquid crystalline homo and block copolymerthacrylates synthesized by organolanthanide complexes 1999 Europolymer Conference 1999 (EUPOC '99) Regular Macromolecular Structures Based on the Controlled Polymerization Processes Europolymer Conference 1999 (EUPOC '99) Regular Macromolecular Structures Based on the Controlled Polymerization Processes Gargnano, Italy 1999-05-23 1999-05-28 2016-02-19 OPUS4-11226 Beitrag zu einem Tagungsband Krietsch, Torsten; Wolff, Dietmar; Knopp, U.; Brocke, H.-D. Behaviour of neutron moderator materials at high temperatures in CASTOR-casks - qualification and assessment Berlin BAM IAEA 2004 PATRAM 2004 - 14th International symposium on the packaging and transportation of radioactive materials (Proceedings) 14 14th International Symposium on the Packaging and Transportation of Radioactive Materials Berlin, Germany 2004-09-20 2004-09-24 235 1 8(?) 2016-02-19 OPUS4-28091 Vortrag Wolff, Dietmar Long term behavior of sealing systems and neutron shielding materials 2013 IAEA - 1st RCM of CRP on demonstrating performance of spent fuel and related system components during very long term storage IAEA - 1st RCM of CRP on demonstrating performance of spent fuel and related system components during very long term storage Villa General Belgrano, Argentina 2013-04-15 2013-04-19 2016-02-20 OPUS4-28476 Vortrag Wolff, Dietmar Investigating the Performance of Rubber Seals at low Temperatures 2013 2013 International High-Level Radioactive Waste Management Conference 2013 International High-Level Radioactive Waste Management Conference Albuquerque, NM, USA 2013-04-28 2013-05-02 2016-02-20 OPUS4-28530 Beitrag zu einem Tagungsband Wolff, Dietmar; Jaunich, Matthias; Stark, Wolfgang Investigating the performance of rubber seals at low temperatures Rubbers are widely used as main sealing materials for Containers for low and intermediate level radioactive waste and as additional component to metal seals in spent fuel and high active waste containers. The save enclosure of the radioactive container inventory has to be guaranteed according to legislation and appropriate guidelines for long term storage periods as well as down to temperatures of -40 °C for transportation. Therefore the understanding of failure mechanisms that lead to leakage at low temperatures is necessary to ensure a proper material choice which is certainly also influenced by additional factors as e.g. the aging behavior. 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 1 7(Paper # 6888) 2016-02-20 OPUS4-25660 Vortrag Wolff, Dietmar Nachweisstrategien zur Behältersicherheit unter Berücksichtigung von Alterungseffekten und Störfallszenarien 2012 3. RAM-Behältersicherheitstage 2012, BAM 3. RAM-Behältersicherheitstage 2012, BAM Berlin, Germany 2012-03-22 2012-03-23 2016-02-19 OPUS4-26190 Beitrag zu einem Tagungsband Jaunich, Matthias; Stark, Wolfgang; Wolff, Dietmar Low temperature - For a seal this depends on the applied material Frankfurt am Main Deutsche Kautschuk-Gesellschaft 2012 DKT 2012 - German Rubber Conference DKT 2012 - German Rubber Conference Nuremberg, Germany 2012-07-02 2012-07-05 10-2330_5-L-1530 1 4 2016-02-19 OPUS4-26175 Beitrag zu einem Tagungsband Völzke, Holger; Probst, Ulrich; Wolff, Dietmar; Nagelschmidt, Sven; Schulz, Sebastian Seal and closure performance in long term storage 2012 PSAM 11 ESREL 2012 - 11th International probabilistic safety assessment and management conference & The annual european safety and reliability conference (Proceedings) PSAM 11 ESREL 2012 - 11th International probabilistic safety assessment and management conference & The annual european safety and reliability conference Helsinki, Finland 2012-06-25 2012-06-29 1 8(?) 2016-02-19 OPUS4-26176 Beitrag zu einem Tagungsband Wolff, Dietmar; von der Ehe, Kerstin; Jaunich, Matthias; Böhning, Martin Performance of neutron radiation shielding material (U)HMW-PE influenced by gamma radiation 2012 PSAM 11 ESREL 2012 - 11th International probabilistic safety assessment and management conference & The annual european safety and reliability conference (Proceedings) PSAM 11 ESREL 2012 - 11th International probabilistic safety assessment and management conference & The annual european safety and reliability conference Helsinki, Finland 2012-06-25 2012-06-29 1 8(?) 2016-02-19 OPUS4-27931 Beitrag zu einem Sammelband Wolff, Dietmar; von der Ehe, Kerstin; Jaunich, Matthias; Böhning, Martin; Goering, Harald Yamamoto, T. (U)HMWPE as neutron radiation shielding materials: impact of gamma radiation on structure and properties Due to their extreme high hydrogen contents, high molecular weight (HMW-) and ultra-high molecular weight (UHMW-) polyethylene (PE) are a comprehensible choice as neutron radiation shielding material in casks for storage and transport of radioactive materials. But as a direct consequence of inserting radioactive material in such casks, gamma radiation occurs. Hence, the impact of gamma radiation on the molecular structure of polyethylene has to be taken into consideration. Consequently, PE has to withstand any type of gamma radiation induced degradation affecting safety relevant aspects in order to be applicable for long term neutron radiation shielding purposes during the whole storage period (in Germany, for instance, up to 40 years). The scope of our investigation comprises an estimation of the impact of gamma radiation and temperature on the molecular and supra molecular structure of the two types of PE used as neutron radiation shielding cask components. A further point which is worth exploring is to what extent these changes are detectable by conventional analysis methods. Therefore, thermoanalytical measurements were performed such as differential scanning calorimetry (DSC), thermo mechanical analysis (TMA), dynamic mechanical analysis (DMA), and thermo gravimetric analysis (TGA). Additionally optical and weighing methods were applied. With those methods it is possible to detect structural changes in polyethylene induced by exposure to gamma radiation. The observed amounts of changes of the irradiated material are not safety relevant for the application of polyethylene as neutron radiation shielding material; moreover, some properties actually improve via irradiation. ASTM International (American Society for Testing and Materials) 2013 Effects of radiation on nuclear materials 25 978-0-8031-7533-4 STP 1547 211 227 10.1520/STP103980 2016-02-20 OPUS4-28574 Beitrag zu einem Tagungsband Jaunich, Matthias; Stark, Wolfgang; Wolff, Dietmar Behaviour of rubber seals at low temperatures - results of component tests - The investigation of low temperature properties of elastomeric sealing materials by means of thermo-analytical methods is a sound way to get information about the glass transition process. The breakdown temperature of the sealing function of O-ring seals was measured in a component test setup depending on material and degree of compression. An in depth explanation of the observed component tests behaviour is currently in preparation. It requires the results of thermo-analytical methods and measurements as the compression set (not shown here). With that, a model was developed to describe the correlation between physical material parameters and observed component behaviour. Kerntechnische Gesellschaft e.V. (KTG) 2013 Jahrestagung Kerntechnik 2013 (Proceedings) Jahrestagung Kerntechnik 2013 Berlin, Germany 14.05.2013 16.05.2013 1 6 2016-02-20 OPUS4-28585 Beitrag zu einem Tagungsband Herbrich, Uwe; Nagelschmidt, Sven; Weber, Wolfgang; Wolff, Dietmar; Völzke, Holger Die sicherheitstechnische Behälterbegutachtung für die trockene Zwischenlagerung bestrahlter Brennelemente aus Sicht der BAM Kerntechnische Gesellschaft e.V. (KTG) 2013 Jahrestagung Kerntechnik 2013 (Proceedings) Jahrestagung Kerntechnik 2013 Berlin, Germany 2013-05-14 2013-05-16 1 6(?) 2016-02-20 OPUS4-28587 Beitrag zu einem Tagungsband Feutlinske, Karl; Wolff, Dietmar; Völzke, Holger Sicherheitsbewertung von Lagerbehältern bei Auslaufen einer befristeten Zwischenlagergenehmigung Bei der sicherheitstechnischen Begutachtung der behälterspezifischen Aspekte nach Ablauf einer Zwischenlagergenehmigung ist entsprechend einer Neubeantragung zu verfahren. Die Sicherheitsbewertung erfolgt nach dem aktuellen Stand von Wissenschaft und Technik bei Berücksichtigung der zur Behälterbauart bereits vorliegenden Sicherheitsnachweise und Begutachtungsergebnisse sowie der physikalischen und chemischen Alterungseinflüsse der bisherigen Zwischenlagerung. Am Beispiel einer beantragten weiteren Zwischenlagerung nach Auslaufen einer auf 20 Jahre befristeten Genehmigung und dem notwendigen Behältertransport zu einem neuen Zwischenlager werden Erfahrungen bzgl. der durchgeführten Sicherheitsbewertung zur Erfüllung der Technischen Annahmebedingungen des neuen Behälterlagers dargestellt. Kerntechnische Gesellschaft e.V. (KTG) 2013 Jahrestagung Kerntechnik 2013 (Proceedings) Jahrestagung Kerntechnik 2013 Berlin, Germany 2013-05-14 2013-05-16 Paper 8816 1 6 2016-02-20 OPUS4-24620 Beitrag zu einem Tagungsband von der Ehe, Kerstin; Jaunich, Matthias; Wolff, Dietmar UHMW-PE - a shielding material with special properties influenced by radiation Ultra high molecular weight polyethylene (UHMW-PE) - due to its high hydrogen content - is used as neutron shielding material in casks for storage and transport of radioactive materials. Besides this, UHMW-PE - as a high-performance polymer - has been used for several years in medical technology due to its excellent slip and wear properties. Due to the special properties of UHMW-PE which result basically from its extreme chain lengths and its high degree of crystallinity, it is predestinated for the aforementioned applications. In both cases, irradiation and its impact on the molecular structure of polyethylene play an important role. In the first case, irradiation exists as a by-product of inserting the radioactive material in the cask. Hence PE has to withstand any type of degradation affecting safety relevant aspects to be applicable for long term radiation shielding purposes for instance over a period of 40 years. In the second case irradiation is applied deliberately for purposes such as sterilization and crosslinking, leading to partial improvement of the mechanical properties (e.g. fracture toughness, crack propagation resistance, wear resistance) and better Chemical stability. Specifically concerning their use in the field of medical technology, different types of UHMW-PE have been objects of numerous publications. It is generally accepted that two parallel and competitive processes, based on chain scission and reactions of Ccentered radicals and molecular fragments, occur in PE as a consequence of radiation: radical recombination accounts for crosslinking, together with some disproportionation, formation of low molecular weight fragments, and recrystallization. Furthermore, formation of oxygenated structures in the presence of traces of oxygen is an antagonist of the C-centered radicals. Radiation induced scission preferentially takes place in the amorphous phase and noncrystalline surface of the crystals. It is followed by folding of molecular fragments, crystallinity growth and increased perfection in the crystal lamellae [4, 5]. Chain scission results in shorter polymer molecules, fewer entanglements, and consequently, increased molecular mobility. The scope of our investigation comprises an estimation of the radiation and thermal impact on the molecular and supra molecular structure of the two types of PE used for neutron shielding cask components. A further point which is worth to explore is to what extent these changes are detectable by thermo-analytical (TA) methods, such as Differential Scanning Calorimetry (DSC), Thermo Mechanical Analysis (TMA), Dynamic Mechanical Analysis (DMA) and Thermogravimetry (TG). Additionally FT-IR and solubility measurements have been performed. In our studies we focused on the UHMW-PE material GUR 4120 which was y irradiated at RT and compared to the untreated material. Deutsches Atomforum e.V. / Kerntechnische Gesellschaft e.V. 2011 Jahrestagung Kerntechnik 2011 (Proceedings) Jahrestagung Kerntechnik 2011 Berlin, Germany 17.05.2011 19.05.2011 1 5 2016-02-19 OPUS4-24621 Beitrag zu einem Tagungsband von der Ehe, Kerstin; Jaunich, Matthias; Wolff, Dietmar; Böhning, Martin; Goering, Harald Radiation induced structural changes of (U)HMW polyethylene with regard to its application for radiation shielding The special properties of high molecular weight polyethylene (HMW-PE) and ultra high molecular weight polyethylene (UHMW-PE) result basically from their extreme chain lengths and their high degree of crystallinity. As high-performance polymers, they are used for a variety of applications. UHMW-PE in particular is often utilized for endoprothesis (due to its excellent slip and wear properties) and due to its high hydrogen content as a neutron moderator in casks for storage and transport of radioactive materials. To prepare the material for instance for its use as a total joint replacement, it is exposed to radiation for several reasons, such as sterilization and crosslinking, leading to partial improvement of the mechanical properties (e.g. fracture toughness, crack propagation resistance, wear resistance) and better chemical stability. To be applicable for long term radiation shielding purposes for instance over a period of 40 years, PE has to withstand any type of degradation affecting safety relevant aspects. The scope of our investigation comprises an estimation of the radiation impact on the molecular and supra molecular structure of two types of PE and to what extent these changes are detectable by thermo-analytical (TA) methods, such as Differential Scanning Calorimetry (DSC), Thermo Mechanical Analysis (TMA), Dynamic Mechanical Analysis (DMA) and Thermo Gravimetric Analysis (TGA). Additionally FT-IR spectroscopy as well as density and gas sorption measurements were carried out. Due to the poor solubility of HMW-PE and UHMW-PE, some classical analytical techniques are not applicable. But TA-methods represent a feasible approach to detect structural and morphological features of these materials as well as changes caused by external influences, such as thermal treatment and/or irradiation. With the combination of the applied TA-techniques it is possible to distinguish between crosslinking and degradation. 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 (T25/Paper 173) 2016-02-19 OPUS4-24971 Beitrag zu einem Tagungsband Jaunich, Matthias; Schulz, Sebastian; Stark, Wolfgang; Wolff, Dietmar Characterization of the low temperature behaviour of rubber sealing materials Rubbers are often used for seal applications due to their special material properties and easy use. In many applications the material is exposed to low temperatures during Operation. Therefore it is important to know the material behavior at low temperatures to determine the temperature ränge that allows a Safe Operation of the seal, e.g. in storage and transport Containers for radioactive materials. The seal function of an elastomer is limited in temperature by the rubber-glass transition during which the material properties change from rubber-like to stiff and glass-like. For a given application this correlation is not trivial and therefore needs an in-depth investigation under consideration of the physical properties and the application conditions. In this work different analytical methods are used to characterize the material behavior at low temperature in the ränge of the glass-rubber-transition and are compared with the quality of Operation of a component which is here defined by the detected leakage rate. 2011 Technomer 2011 - 22. Fachtagung über Verarbeitung und Anwendung von Polymeren 978-3-939382-10-2 Technomer 2011 - 22. Fachtagung über Verarbeitung und Anwendung von Polymeren Chemnitz, Deutschland 10.11.2011 12.11.2011 Kap. 3.7 1 4 2016-02-19 OPUS4-27405 Forschungsbericht Völzke, Holger; Wolff, Dietmar Extended storage collaboration program international subcommittee report: International perspectives on technical data gaps associated with extended storage and transportation of used nuclear fuel Final report Palo Alto, CA, USA EPRI - Electric power research institute 2012 1026481 Chapter 2.1, 3.1, 4.1 2-1 - 2-5, 3-1 - 3-4, 4-1 - 4-3 2016-02-20 OPUS4-27557 Beitrag zu einem Tagungsband Völzke, Holger; Wolff, Dietmar; Kasparek, Eva Maria; Botsch, W.; Drotleff, H.-W.; Hinterding, P.; Smalian, S. Safety aspects of dry spent fuel storage and spent fuel management European nuclear society 2012 ENC 2012 - European nuclear conference - Transactions - Fuel cycle 978-92-95064-14-0 ENC 2012 - European nuclear conference - Transactions - Fuel cycle Manchester, UK 2012-12-09 2012-12-12 ENC2012-A0054 1 5 2016-02-20 OPUS4-26261 Zeitschriftenartikel Kasparek, Eva Maria; Völzke, Holger; Scheidemann, Robert; Zencker, Uwe; Wolff, Dietmar Experimental and numerical studies of shock absorbing materials for containers for radioactive waste Berlin Inforum Kerntechnische Gesellschaft 2012 Atw 57 6 397 401 2016-02-19 OPUS4-15893 Vortrag Wolff, Dietmar Long-term storage facility for reactor compartments in Sayda Bay - German support for utilization of nuclear submarines in Russia - 2007 11th International Conference on Environmental Remediation and Radioactive Waste Management ICEM2007, Qud Sint-Jan Hospital Conference Center 11th International Conference on Environmental Remediation and Radioactive Waste Management ICEM2007, Qud Sint-Jan Hospital Conference Center Bruges, Belgium 2007-09-02 2007-09-06 2016-02-19 OPUS4-17540 Zeitschriftenartikel Probst, Ulrich; Hagenow, Peter; Völzke, Holger; Wolff, Dietmar; Wossidlo, Peter; Abbasi, Behboud; Achelpöhler-Schulte, Andreas; Schulz, Sebastian Investigation of seal effects according to axial compression variation of metal seals for transport and storage casks Casks for the transport and storage of heat generating radioactive waste in Germany are normally provided with screwed lid systems, which are in most cases equipped with double jacket metal seals with an inner spring wire to provide long term resistance to the seal compression force. Preservation of the high sealing quality of those seals under operational and accidental stress conditions is essentially important to the safety of those casks. Relative displacements of the lid system surfaces caused by specific impact scenarios cannot be excluded and have to be evaluated with respect to a possible increase in the leakage rate. To get representative data for such metal sealed lid systems, BAM has developed a special conceptualised flange system placed in an appropriate testing machine for relevant mechanical loading of the metal seals under static and cyclic conditions. Furthermore, the flange system enables continuous measurement of the standard helium leakage rate during each test. The primary aim of the investigation is to identify the correlation between variation of installation conditions (axial displacements) caused by external loads and the standard helium leakage rate. An essential parameter in this case is the useable resilience ru of a metal seal under relevant stress conditions. The useable resilience ru is the vertical difference in the cross-section between the seal's assembling status and the point where the leakage rate, by means of external load relieving, exceeds the quality criterion of 10-8 Pa m3 s-1. Load relieving can instantly occur due to modification of the seal groove dimension caused by accident impacts and deformation of the lid system. Furthermore, component specific basis data for the development of finite element calculation models should be collected. In the tests, seals are subjected to static and cyclic loads. All tests are performed at ambient temperature. This paper presents the test configuration, different test series and results of the current experiments. Typical load-displacement-leakage rate correlations are presented and discussed. Ashford Ramtrans Publ. 2008 Packaging, transport, storage & security of radioactive materials (RAMTRANS) 19 1 47 52 10.1179/174651008X278948 2016-02-19 OPUS4-17542 Beitrag zu einem Tagungsband Probst, Ulrich; Hagenow, Peter; Völzke, Holger; Wolff, Dietmar; Wossidlo, Peter; Abbasi, Behboud; Achelpöhler-Schulte, Andreas; Schulz, Sebastian Investigation of seal effects according to axial compression variation of metal seals for transport and storage casks 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 1 8 2016-02-19 OPUS4-4692 Vortrag Wolff, Dietmar Safety Aspects of Long-term Dry Interim Storage of Type-B Spent Fuel and HLW Transport Casks 2004 14th International Symposium on the Packaging and Transportation of Radioactive Materials (PATRAM 2004) 14th International Symposium on the Packaging and Transportation of Radioactive Materials (PATRAM 2004) Berlin, Germany 2004-09-20 2004-09-24 2016-02-19 OPUS4-14441 Zeitschriftenartikel Wieser, Günter; Qiao, Linan; Völzke, Holger; Wolff, Dietmar; Droste, Bernhard Safety analysis of casks under extreme impact conditions Ashford Ramtrans Publ. 2004 Packaging, transport, storage & security of radioactive materials (RAMTRANS) 15 2 141 147 2016-02-19 OPUS4-16157 Beitrag zu einem Tagungsband Erhard, Anton; Völzke, Holger; Noack, Volker; Weber, Wolfgang; Wolff, Dietmar; Rittscher, D.; Schmidt, H. Long term interim storage facility for nuclear reactor compartments of submarines - German support for utilization of nuclear submarines in Russia 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 2007-10-26 155 2016-02-19 OPUS4-17708 Zeitschriftenartikel Erhard, Anton; Völzke, Holger; Noack, Volker; Weber, Wolfgang; Wolff, Dietmar; Rittscher, D.; Schmidt, H. Construction of long term interim storage facility for nuclear reactor compartments of submarines: German support for utilisation of nuclear submarines in Russia Ashford Ramtrans Publ. 2008 Packaging, transport, storage & security of radioactive materials (RAMTRANS) 19 2 117 121 2016-02-19 OPUS4-7372 Vortrag Wolff, Dietmar Safety Analysis of Spent Fuel Transport and Storage Casks under Extreme Impact Conditions 2005 International Conference on Nuclear Energy and Security International Conference on Nuclear Energy and Security Salzburg, Austria 2005-07-20 2005-07-23 2016-02-19 OPUS4-28998 Vortrag Wolff, Dietmar Updating report on R&D concerning technical data gaps - Germany (BAM) - Long Term Behavior of Sealing systems and Neutron Shielding Materials 2013 8th International Subcommittee meeting as part of the Extended Storage Collaboration Program (ESCP) 8th International Subcommittee meeting as part of the Extended Storage Collaboration Program (ESCP) Munich, Germany 2013-05-24 2016-02-20 OPUS4-29009 Vortrag Wolff, Dietmar Extended Storage after Long-term Storage 2013 17th International Symposium on the Packaging and Transportation of Radioactive Materials (PATRAM 2013) 17th International Symposium on the Packaging and Transportation of Radioactive Materials (PATRAM 2013) San Francisco, CA, USA 2013-08-18 2013-08-23 2016-02-20 OPUS4-29221 Beitrag zu einem Tagungsband Jaunich, Matthias; Wolff, Dietmar; Stark, Wolfgang Riedl, A. Was passiert bei tiefen Temperaturen? - Dichtungsverhalten im Bereich des Glasübergangs Elastomere werden vielfach als Dichtungsmaterial für verschiedene Anwendungen eingesetzt. In vielen Bereichen ist die Funktion der Dichtung auch bei tiefen Temperaturen erforderlich. Daher ist das Verständnis des Versagensmechanismus von großer Bedeutung. Normalerweise werden Elastomere oberhalb ihres Glass-Gummi Umwandlungsbereiches eingesetzt, wobei die minimale Einsatztemperatur nicht exakt definiert ist. Daher ist es sinnvoll, diese untere Temperatureinsatzgrenze in Abhängigkeit von den Materialeigenschaften zu bestimmen. Hierfür werden die Ergebnisse der thermischen Analyse mit den Resultaten des Druckverformungsrests aus einer abgewandelten Messung mit der Dynamisch Mechanischen Analyse (DMA) kombiniert. Weiterhin werden Ergebnisse von Bauteilversuchen vorgestellt und diskutiert. Die vorgestellten Untersuchungen wurden zum großen Teil auf Untersuchungen im Rahmen der Dissertation von M. Jaunich durchgeführt. Vulkan 2013 XVIII. Dichtungskolloquium - Sichere und zuverlässige Dichtverbindungen 978-3-8027-2216-5 XVIII. Dichtungskolloquium - Sichere und zuverlässige Dichtverbindungen Rheine, Germany 25.09.2013 26.09.2013 51 58 2016-02-20 OPUS4-29616 Beitrag zu einem Tagungsband Jaunich, Matthias; Stark, Wolfgang; Wolff, Dietmar Druckverformungsrest bei tiefen Temperaturen Für Elastomenwerkstoffe im Allgemeinen und im Bereich der Dichtungstechnik im Besonderen ist der Druckverformungsrest eine wichtige Kenngröße zur Beurteilung der Eignung eines Werkstoffs bzw. der Funktion eines Bauteils. Er ermöglicht eine Einschätzung des zeitabhängigen Rückstellverhaltens eines Werkstoffs nach Deformation. Dieses ist für Dichtungen von besonderer Bedeutung, da der Test deren Einbauzustand nachstellt. Oft wird er, bei der Prüfung unter erhöhten Temperaturen, zur Beurteilung des Alterungsverhaltens verwendet und kann anhand eines definierten Versagenskriteriums zur Lebensdauerabschätzung eingesetzt werden. Bei tiefen Temperaturen dient er dazu, die limitierende Einsatztemperatur zu bestimmen. Dabei spielt eine Alterung im eigentlichen Sinne nur eine untergeordnete Rolle, wohl aber physikalische Effekte wie Tieftemperaturkristallisation und Glasübergang. Diese Effekte sind weit weniger durch lange Lagerzeiten beeinflusst als die eigentliche Alterung. Die Versuchsdurchführung unterscheidet sich je nach angewandter Norm und kann einen deutlichen Einfluss auf den Druckverformungsrest haben. Alle standardisierten Methoden sind aufgrund der langen Lagerzeiten relativ langwierig und erfordern das regelmäßige Eingreifen durch den Prüfer. Zusätzlich sehen einige Methoden nur die Bestimmung eines einzelnen Wertes nach einer definierten Zeit vor. Um die Messungen zu beschleunigen wurde eine Methode entwickelt, die automatisch die erforderlichen Messungen bei mehreren Temperaturen durchführt. Dazu wird ein Prüfgerät der Dynamisch Mechanischen Analyse verwendet, das kontinuierlich die Deformation während eines frei programmierbaren Temperaturzyklus misst, wodurch eine sehr große Datenmenge verfügbar ist. Ein Vergleich der neuen Methode mit den Ergebnissen des nach ISO 815 genormten Messprinzips ergibt eine gute Übereinstimmung. Ergebnisse der neuen Methode werden vorgestellt und die Vorzüge der kontinuierlichen Datenerfassung, z.B. für die Materialauswahl, diskutiert. Die vorgestellten Ergebnisse beziehen sich zum großen Teil auf die in beschriebenen Untersuchungen und Ergebnisse. Technische Universität Chemnitz 2013 Technomer 2013 - 23. Fachtagung über Verarbeitung und Anwendung von Polymeren 978-3-939382-11-9 Technomer 2013 - 23. Fachtagung über Verarbeitung und Anwendung von Polymeren Chemnitz, Germany 14.11.2013 15.11.2013 Kapitel V 3.4 1 8 2016-02-20 OPUS4-29661 Beitrag zu einem Sammelband Jaunich, Matthias; Probst, Ulrich; Schulz, Sebastian; Wolff, Dietmar; Stark, Wolfgang Berger, K.-F.; Kiefer, S. Elastomere - Untersuchung des Tieftemperaturverhaltens im Dichtungseinsatz Aufgrund ihrer einfachen und zuverlässigen Anwendung werden Elastomere für viele Dichtungsaufgaben eingesetzt. In vielen Anwendungsbereichen, wie z.B. Verkehr, Luftfahrt und Verfahrenstechnik, können während des Einsatzes tiefe Temperaturen auftreten, bei denen die Funktionsfähigkeit der Dichtung erhalten bleiben muss. Daher ist die Untersuchung des Verhaltens von Elastomerdichtungen bei tiefen Temperaturen wichtig, um ihren Temperatureinsatzbereich nach unten abzugrenzen und dadurch einen verlässlichen Betrieb zu sichern. Ziel dieser Arbeit ist es, den sicheren Einschluss von gefährlichen Gütern unter verschiedenen Umgebungsbedingungen und über lange Zeiten zu ermöglichen bzw. die Materialauswahl entsprechend zu steuern. Mannheim ISGATEC GmbH 2013 Dichtungstechnik Jahrbuch 2014 978-3-9811509-7-1 82 91 2016-02-20 OPUS4-21272 Beitrag zu einem Tagungsband Jaunich, Matthias; Wolff, Dietmar; Stark, Wolfgang Tieftemperaturverhalten von Elastomerdichtungen - Eigenschaftsbestimmung für den Einsatz in Transport- und Lagerbehältern für radioaktive Stoffe Die Messung des dynamischen Speichermoduls mit der Dynamisch-Mechanischen-Analyse ermöglicht einen schnellen Überblick über das temperaturabhängige Verhalten von elastomeren Dichtungsmaterialien. Ein direkter Rückschluss von der so ermittelten Glasübergangstemperatur Tg auf die Versagenstemperatur einer Dichtung ist aber ohne zusätzliche Messungen bisher nicht möglich. Mit den Ergebnissen des Druckverformungsrestes DVR und des DVRDMA ist eine ge-nauere Beschreibung der Tieftemperatureigenschaften und dadurch der Funktion von elastomeren Dichtungsmaterialien möglich. Messungen ergeben beispielsweise, dass sich das EPDM bei einer Temperatur von -40 °C laut der Dynamisch Mechanischen Analyse noch im gummielastischen Bereich befindet. Die DVRDMA-Werte zeigen eine Rückstellung um mehr als 40 % der Ausgangsdeformation in wenigen Minuten. Mit derart detailliert bestimmten Eigenschaften lassen sich Rückschlüsse auf einsatzspezifische Anforderungen wie z. B. die Dichtwirkung in Abhängigkeit von Betriebstemperatur und mechanischer Belastungsgeschwindigkeit ziehen, so dass je nach Einsatzbedingungen für die Dichtungen eine geeignete Materialauswahl getrof-fen werden kann. Berlin Kerntechnische Gesellschaft e.V. (KTG) 2010 Jahrestagung Kerntechnik 2010 (Proceedings) Jahrestagung Kerntechnik 2010 Berlin, Deutschland 2010-05-04 2010-05-06 Sektion 5 / 503 1 4 2016-02-19 OPUS4-22331 Beitrag zu einem Sammelband Jaunich, Matthias; Stark, Wolfgang; Wolff, Dietmar Low temperature properties of rubber seals Deutsches Institut für Kautschuktechnologie e.V. 2010 9th Fall rubber colloquium 978-3-9814076-0-0 9th Fall rubber colloquium Hannover, Germany 2010-11-03 2010-11-05 175 178 2016-02-19 OPUS4-20707 Beitrag zu einem Tagungsband Völzke, Holger; Wolff, Dietmar; Probst, Ulrich Advanced investigations to evaluate spent fuel cask safety for extended storage periods Institute of Nuclear Materials Management (INMM) 2009 50th Annual Meeting of the Institute of Nuclear Materials Management INMM (Proceedings) 50th Annual Meeting of the Institute of Nuclear Materials Management (INMM) Tucson, Arizona, USA 2009-07-12 2009-07-16 1 10 2016-02-19 OPUS4-20989 Vortrag Wolff, Dietmar Schwerpunkte bei der Behälterbegutachtung aus Sicht der BAM 2010 2. RAM-Behältersicherheitstage 2010, BAM 2. RAM-Behältersicherheitstage 2010, BAM Berlin, Germany 2010-03-18 2010-03-19 2016-02-19 OPUS4-23836 Beitrag zu einem Tagungsband Kasparek, Eva Maria; Scheidemann, Robert; Wolff, Dietmar; Zencker, Uwe; Völzke, Holger Untersuchungen zum Verhalten von Dämpferbeton unter Stossbelastung Während des Transportes sind Behälter für hoch radioaktive Abfälle durch stoßdämpfende Bauteile vor Einwirkungen, die aus Unfallszenarien gemäß den IAEA Regularien resultieren können, weitestgehend geschützt. Nach dem Entfernen dieser Komponenten im Rahmen der Einlagerung ins Zwischenlager müssen Vorkehrungen getroffen sein, um Beanspruchungen der Behälter aus möglichen Handhabungsunfällen im Empfangsbereich zu reduzieren. Die Maßnahmen müssen vor allem darauf abzielen, die stoßdämpfenden Eigenschaften der potentiellen Aufprallflächen zu optimieren. Da Standardmaterialien für Fundamente nur ein geringes Energieabsorptionsvermögen aufweisen, wurde durch die Firma HOCHTIEF eine neuartige Betonmixtur entwickelt, bei der ein spezieller Leichtzuschlag zum Einsatz kommen. Zur Charakterisierung dieses sogenannten Dämpferbetons liegen Standardkennwerte vor sowie Messwerte aus Eindringversuchen, die zur Qualitätssicherung für jede Produktcharge durchgeführt werden. Das stoßdämpfende Potential des neuen Werkstoffs kann jedoch nur dann vollkommen ausgeschöpft werden, wenn die Energieabsorption in numerischen Simulationen der Behälterabstürze über die gesamte Belastungsdauer zuverlässig wiedergegeben wird. Für die Implementierung und Anpassung eines entsprechenden Materialmodelis in einem Finite Elemente (FE) Programm sind Daten aus systematischen Druckversuchen mit Variation der relevanten Einflussgrößen erforderlich. An der BAM werden daher im Rahmen eines werkstoffübergreifenden Forschungsvorhabens zur Untersuchung von stoßdämpfenden Strukturen auch die Eigenschaften von Dämpferbeton experimentell untersucht und zugehörige numerische Methoden entwickelt. Der aktuelle Beitrag behandelt die Ergebnisse der ersten Projektphase, in der kubische Probekörper mit der Kantenlänge 100mm bei unterschiedlichen Lagerungsbedingungen statisch und dynamisch gestaucht wurden. In nachfolgenden Versuchen wird der Einfluß der Probengröße ermittelt sowie die Eignung der verwendeten Materialmodelle anhand realistischer Belastungssituationen validiert. Versuchsprogramm. Deutsches Atomforum e.V. / Kerntechnische Gesellschaft e.V. 2011 Jahrestagung Kerntechnik 2011 (Proceedings) Jahrestagung Kerntechnik 2011 Berlin, Germany 17.05.2011 19.05.2011 Session TS-17 / Paper 171 1 5 2016-02-19 OPUS4-23839 Vortrag Wolff, Dietmar Safety Aspects of Long-Term Dry Interim Storage of Spent Fuel in Germany 2011 Technical Meeting on Very Long Term Storage of Used Nuclear Fuel; IAEA Technical Meeting on Very Long Term Storage of Used Nuclear Fuel; IAEA Vienna, Austria 2011-04-26 2011-04-28 2016-02-19 OPUS4-26524 Beitrag zu einem Tagungsband Jaunich, Matthias; Stark, Wolfgang; Wolff, Dietmar Material behaviour of static seals at low temperatures Frankfurt/M. VDMA Fluidtechnik 2012 17th ISC - International sealing conference 978-3-00-039198-9 17th ISC - International sealing conference Stuttgart, Germany 2012-09-13 2012-09-14 A 16 295 300 2016-02-19 OPUS4-26538 Zeitschriftenartikel Jaunich, Matthias; Stark, Wolfgang; Wolff, Dietmar Comparison of low temperature properties of different elastomer materials investigated by a new method for compression set measurement The method for the determination of compression set values with a Dynamic Mechanical Analysis (DMA) setup at low temperatures, which was presented previously, allows a much faster and readily automated procedure than the standardized compression set test according to ISO 815-2. This method is applied to a series of different elastomeric materials that are commonly used for sealing applications. The results of the compression set test are compared with results from thermal analysis to allow an in depth comparison of the material behaviour at low temperatures. Furthermore, a comparison between two EPDM materials is presented. These materials show very similar properties determined by thermo analytical methods such as Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) but differ clearly in their compression set behaviour. This comparison shows the importance and value of information of the compression set test in addition to thermal analysis to judge the behaviour of sealing materials and confirms the relevance of the new compression set test method for the investigation of low temperature properties of elastomers. Amsterdam [u.a.] Elsevier Science 2012 Polymer testing 31 8 987 992 10.1016/j.polymertesting.2012.07.016 2016-02-19 OPUS4-26815 Vortrag Wolff, Dietmar Long-termin Storage and Aging Management issues in Dry Interim Cask Storage (international and national perspectives) 2012 Workshop KAERI (Korean Atomic Energy Research Institute) - BAM Workshop KAERI (Korean Atomic Energy Research Institute) - BAM Daejeon, South Korea 2012-09-11 2012-09-13 2016-02-19 OPUS4-26816 Vortrag Wolff, Dietmar Experiences in safety evaluation of spent fuel cask designs for interim storage 2012 Workshop KAERI (Korean Atomic Energy Research Institute) - BAM Workshop KAERI (Korean Atomic Energy Research Institute) - BAM Daejeon, South Korea 2012-09-11 2012-09-13 2016-02-19 OPUS4-26995 Beitrag zu einem Tagungsband Jaunich, Matthias; Wolff, Dietmar; Stark, Wolfgang Low temperature properties of rubber seals - results of component tests Deutsches Institut für Kautschuktechnologie e.V. 2012 10th Fall rubber colloquium (Proceedings) 978-3-9814076-1-7 10th Fall rubber colloquium Hannover, Germany 2012-11-07 2012-11-09 khk2012_jaunich.pdf 1 8 2016-02-19 OPUS4-27129 Zeitschriftenartikel Turky, Gamal; Wolff, Dietmar; Schönhals, Andreas Confinement effects on the molecular dynamics of liquid-crystalline polymethacrylates - a broadband dielectric spectroscopy study The molecular dynamics of liquid-crystalline polymethacrylates with biphenyl in the side group forming a highly ordered smectic E phase at low temperatures is investigated by dielectric spectroscopy (DS). Although no glass transition is found by DSC, DS detects a relaxation in the smectic E phase resembling to glassy dynamics. The temperature dependence of its relaxation rate is Arrhenius like at low temperatures, which changes to a VFT law at higher temperatures. Such a behavior is found to be characteristic for glassy dynamics in confining space. It is discussed, considering the structure of the polymers as nanobiphasic consisting of liquid-crystalline layers while the backbones fill the interlayer space. A comparison is made to polymethacrylates having phenyl benzoate as mesogen. Weinheim Wiley-VCH Verl. 2012 Macromolecular chemistry and physics 213 22 2420 2431 10.1002/macp.201200361 2016-02-19 OPUS4-26129 Vortrag Wolff, Dietmar Performance of neutron radiation shielding material (U)HMW-PE influenced by gamma radiation 2012 PSAM11 PSAM11 Helsinki, Finland 2012-06-25 2012-06-29 2016-02-19 OPUS4-27395 Vortrag Wolff, Dietmar Behavior of rubber seals at low temperatures and neutron radiation shielding material under influence of gamma radiation 2012 Savannah River National Laboratory Workshop Savannah River National Laboratory Workshop Aiken, SC, USA 2012-12-03 2012-12-03 2016-02-20 OPUS4-29762 Vortrag Wolff, Dietmar German (BAM) status of R&D programs on seals and polymers 2013 9th International Subcommittee meeting as part of the extended Storage Collaboration Programm (ESCP) 9th International Subcommittee meeting as part of the extended Storage Collaboration Programm (ESCP) Charlotte, NC, USA 2013-12-05 2013-12-05 2016-02-20 OPUS4-30159 Beitrag zu einem Tagungsband Wille, Frank; Wolff, Dietmar; Droste, Bernhard; Völzke, Holger; Baden, M. German approach and experience feedback of transport ability of SNF packages after interim storage In Germany the concept of dry interim storage of spent fuel in dual purpose metal casks is implemented, currently for periods of up to 40 years. The casks being used have an approved package design in accordance with the international transport regulations. The license for dry storage is granted on the German Atomic Energy Act with respect to the recently revised "Guidelines for dry interim storage of irradiated fuel assemblies and heat-generating radioactive waste in casks" by the German Waste management Commission (ESK). For transport on public routes between or after long term interim storage periods, it has to be ensured that the transport and storage casks fulfil the specifications of the transport approval or other sufficient properties which satisfy the proofs for the compliance of the safety objectives at that time. In recent years the validation period of transport approval certificates for manufactured, loaded and stored packages were discussed among authorities and applicants. A case dependant system of 3, 5 and 10 years was established. There are consequences for the safety cases in the Package Design Safety Report including evaluation of long term behavior of components and specific operating procedures of the package. Present research and knowledge concerning the long term behavior of transport and storage cask components have to be consulted as well as experiences from interim cask storage operations. Challenges in the safety assessment are e.g. the behavior of aged metal and elastomeric gaskets under IAEA test conditions to ensure that the results of drop tests can be transferred to the compliance of the safety objectives at the time of transport after the interim storage period. 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 1 9 2016-02-20 OPUS4-30135 Beitrag zu einem Tagungsband Erhard, Anton; Völzke, Holger; Droste, Bernhard; Wolff, Dietmar; Wille, Frank Nuclear power plant waste management strategy in Germany 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 2013-08-18 2013-08-23 1 11(?) 2016-02-20 OPUS4-30136 Beitrag zu einem Tagungsband Völzke, Holger; Wolff, Dietmar; Probst, Ulrich; Nagelschmidt, Sven; Schulz, Sebastian Long-term performance of metal seals for transport and storage casks Dual purpose casks for the transportation and storage of spent nuclear fuel and other radioactive materials require very high leak-tightness of lid closure Systems under accident conditions as well as in the long-term to prevent activity release. For that purpose metal seals of specific types with an inner helical spring and outer metal liners are widely used and have shown their excellent performance if certain quality assurance requirements for fabrication and assembling are satisfied. Well defined surface roughness, clean and dry inert conditions are therefore essential. No seal failure in a loaded cask happened under these conditions until today. Nevertheless, the considered and licensed Operation period is limited and all safety assessments have been performed and approved for this period of time which is 40 years in Germany so far. But in the meantime longer storage periods might be necessary for the future and therefore additional material data will be required. BAM is involved in the qualification and evaluation procedures of those seals from the early beginning. Because long-term tests are always time consuming BAM has early decided to perform additional tests with specific test seal configurations to gain a better understanding of the long-term behavior with regard to seal pressure force, leakage rate and useable resilience which is safety relevant mainly in case of accidental mechanical loads inside a storage facility or during a subsequent transport. Main test parameters are the material of the outer seal jacket (silver or aluminum) and the temperature. This paper presents the BAM test program including an innovative test mock-up and most recent test results. Based on these data extrapolation models to extended time periods are discussed, and also future plans to continue tests and to investigate seal behavior for additional test parameters are explained. 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 1 13 2016-02-20 OPUS4-30140 Beitrag zu einem Tagungsband Kumano, Y.; Droste, Bernhard; Hirose, M.; Harvey, J.; Reiche, I..; Wolff, Dietmar; McConnell, P.; Varley, K. Overview of the IAEA's joint working group on integrated safety case for dual purpose casks 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 2013-08-18 2013-08-23 1 9(?) 2016-02-20 OPUS4-28853 Beitrag zu einem Tagungsband Jaunich, Matthias; Wolff, Dietmar; Stark, Wolfgang Investigating low temperature properties of rubber seals To achieve the required tightness levels of Containers for low and intermediate level radioactive wastes rubbers are widely applied as main sealing materials. The save encapsulation of the radioactive Container contents has to be guaranteed according to legislation and appropriate guidelines for long storage periods as well as down to temperatures of-40 °C during transportation. Therefore the understanding of failure mechanisms that lead to leakage at low temperatures is of high importance. It is known that the material properties of rubbers are strongly influenced by temperature. At low temperatures this is caused by the rubber-glass transition (abbr. glass transition). During continuous cooling the material changes from rubber-like entropy-elastic to stiff energy-elastic behaviour, that allows nearly no strain or retraction. Therefore, rubbers are normally used above their glass transition but the minimum working temperature limit is not defrned precisely, what can cause problems during application. The temperature ränge where full functionality is possible is strongly dependent on the application conditions and the material. For this investigation mainly ethylene propylene diene (EPDM) and fluorocarbon rubbers (FKM) were selected as they are often used for radioactive waste Containers. Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) are typically used for the determination of the temperature ränge of the glass transition process. The standardized compression set measurement according to ISO 815 is common for investigation of rubber sealing materials as the test simulates the seal behaviour after release. To reduce the test time of the Standard tests a faster technique giving the same information was developed. Additionally, the breakdown temperature of the sealing function of complete O-ring seals is measured in a component test Setup to compare it with the results of the other tests. The experimental Setup is capable of measuring the leakage rate at low temperatures by the pressure rise method. A model was developed that allows calculating the minimum working temperature limit of a seal by combining the results of the applied methods. Phoenix, Arizona, USA 2013 WM2013 Conference (Proceedings) 978-0-9836186-2-1 WM2013 Conference Phoenix, Arizona, USA 24.02.2013 28.02.2013 1 12 2016-02-20 OPUS4-28912 Beitrag zu einem Sammelband Probst, Ulrich; Schulz, Sebastian; Jaunich, Matthias; Wolff, Dietmar; Völzke, Holger Berger, K.-F.; Kiefer, S. Langzeituntersuchungen an Metalldichtungen mit innen liegendem Federkern und doppelter Ummantelung In Deutschland werden in Transport- und Lagerbehältern (TLB) wärmeentwickelnde radioaktive Abfälle gegenwärtig über einen Zeitraum von bis zu 40 Jahren zwischengelagert. Aufgrund der Situation der noch nicht abgeschlossenen Endlagersuche werden hier möglicherweise Verlängerungen in Betracht zu ziehen sein. Im Deckeldichtsystem der TLB werden in der Regel Metalldichtungen vom Typ Helicoflex® eines französischen Herstellers verwendet, die aus einem innen liegenden Spiralfederkern und zwei Ummantelungen bestehen. Die Ermittlung der Fliess- und Relaxationseigenschaften der Dichtungskomponenten über den vorgesehenen langen Betriebseitraum sind vor dem Hintergrund des Erhalte eines geforderten hohen Dichtniveaus ein wichtiger Untersuchungsgegenstand. Mannheim ISGATEC GmbH 2013 Dichtungstechnik Jahrbuch 2014 978-3-9811509-7-1 1 11 2016-02-20 OPUS4-28894 Zeitschriftenartikel Jaunich, Matthias; Wolff, Dietmar; Stark, Wolfgang Low temperature properties of rubber seals - Results of component tests - Rubbers are widely used as sealing material in various applications. In many fieldsthefunction of seal materials at lowtemperatures is required. Therefore the understanding of faiiure mechanisms that lead to leakage at low temperatures is of high importance. Therefore the lower Operation temperature limit of rubber seals should be determined in dependence of the material properties. The results of Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) are combined with results of standardized measurements as the compression set according to ISO 815. To reduce the test time of the Standard tests a faster and more efficient technique was developed and applied. In addition the breakdown temperature of the sealing function of O-ring seals at lowtemperatures is measured in a component test Setup in dependence of the material and the degree of compression. Heidelberg Hüthig Deutsche Kautschuk-Gesellschaft 2013 Kautschuk, Gummi, Kunststoffe (KGK) 66 7-8 26 30 2016-02-20 OPUS4-56398 Zeitschriftenartikel Kömmling, Anja; Grelle, Tobias; Jaunich, Matthias; Goral, Milan; Wolff, Dietmar Three-dimensional thermal expansion of neat and irradiated (U)HMWPE materials at elevated temperatures The thermal expansion of polymeric parts can be an issue in many applications where the available space is limited, or exact dimensions of the part are required. For this study, a device was designed and built that allowed measuring the thermal expansion simultaneously in all three spatial directions on cubic samples with real-scale dimensions (78 mm edge length). The results are shown between 25 °C and 125 °C for two PE materials, one HMWPE and one tempered UHMWPE, for non-irradiated samples as well as cubes that have been irradiated with 100 and 400 kGy. The results measured with the new device were very similar to those measured with conventional thermo-mechanical analysis equipment and to literature data of UHMWPE. The HMWPE material shows a much larger thermal expansion coefficient in one direction compared to the other two directions during the first heating due to frozen stresses from the pressing step during material manufacturing. These stresses are mostly released by the expansion during the first heating, so that the expansion during the second heating is more uniform. The overall volumetric expansion is the same for both heating runs. By contrast, the tempered UHMWPE material shows no significant difference between first and second heating run, as the stresses from processing could already relax in the tempering step. The irradiation treatment does not affect the values significantly for the given test set-up. Elsevier Ltd. 2022 Polymer Testing 117 1 8 urn:nbn:de:kobv:b43-563987 10.1016/j.polymertesting.2022.107841 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2022-11-28 OPUS4-56399 Beitrag zu einem Sammelband Goral, Milan; Kömmling, Anja; Probst, Ulrich; Wossidlo, Peter; Jaunich, Matthias; Wolff, Dietmar; Völzke, Holger Langzeitversuche über 10 Jahre an Federkern-Metalldichtungen mit Aluminium- bzw. Silberummantelungen Federunterstützte Metalldichtungen mit Aluminium(Al)- oder Silber(Ag)-Ummantelung werden u.a. in Behältern für Wärme entwickelnde radioaktive Abfälle eingesetzt, da diese Dichtungen eine sehr gute Dichtheit gewährleisten sowie Langlebigkeit und Beständigkeit gegenüber erhöhten Temperaturen und radioaktiver Strahlung aufweisen. Auch wenn die Sicherheit solcher Behälter und der verwendeten Dichtungen vielfach belegt wurde, sind sie Gegenstand andauernder Forschung, etwa im Hinblick auf eine absehbar benötigte verlängerte Zwischenlagerdauer. Aus diesem Grund werden an der Bundesanstalt für Materialforschung und -prüfung (BAM) im Fachbereich 3.4 „Sicherheit von Lagerbehältern" seit über 20 Jahren Versuche an solchen Metalldichtungen durchgeführt. Dabei sollen zusätzliche Erkenntnisse hinsichtlich der Sicherheitsreserven der Dichtungen in unterstellten Störfallszenarien (axiale Bewegung des Deckelsystems bzw. Aufweitung der Nutgeometrie) und insbesondere detailliertere Erkenntnisse zum Langzeitverhalten gewonnen werden. Mannheim ISGATEC GmbH 2023 JAHRBUCH Dichten. Kleben. Polymer. 2023 2023 43 63 2022-11-28 OPUS4-54591 Zeitschriftenartikel Zaghdoudi, Maha; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Oxidative ageing of elastomers: Experiment and modelling During an extensive test programme at the Bundesanstalt für Materialforschung und prüfung, material property changes of EPDM O-rings were investigated at different ageing times and two ageing temperatures of 125∘C and 150∘C. To exclude possible diffusion-limited oxidation (DLO) effects that can distort the data, IRHD microhardness measurements were taken over the cross section of compressed O-rings. Continuous stress relaxation measurements were taken on samples free of DLO effects. The additional effect of physical processes to irreversible chemical ones during a long-term thermal exposure is quantified by the analysis of compression set measurements under various test conditions. By combining the different experimental methods, characteristic times relative to the degradation processes were determined. On the basis of experimental data, a microphysically motivated model that takes into account reversible and irreversible processes was developed. The parameter identification strategy of the material model is based on our experimental investigations on homogeneously aged elastomer O-rings. The simulated results are in good agreement with the experiments. Berlin Springer 2022 Continuum mechanics and thermodynamics 1 9 urn:nbn:de:kobv:b43-545910 10.1007/s00161-022-01093-9 https://creativecommons.org/licenses/by/4.0/deed.de 2022-04-04 OPUS4-54422 Beitrag zu einem Tagungsband Weber, Mike; Zaghdoudi, Maha; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar A numerical approach to correlate compression stress relaxation and compression set of elastomer O-rings with tightness The excellent mechanical properties of elastomer seals at a wide range of temperatures as well as their high versatility and recovery potential under several load conditions make these materials well suitable for the application in containers designed for transport and disposal of negligible heat generating radioactive waste. While a seal exchange at defined intervals is typical in many conventional applications, it is impossible or at least hard to perform when principles of minimization of radiation exposure have to be considered which prohibit an avoidable cask handling. An extensive knowledge of the change of the elastomer properties during aging and the availability of reliable end-of-lifetime criteria to guarantee the safe enclosure of the radioactive material for the required time are mandatory. As BAM is involved in most of the national cask licensing procedures and in the evaluation of cask-related long-term safety issues, great efforts have already been made and are still ongoing to scientifically support this task. Among other representative types of elastomers, specimen made from ethylene propylene diene rubber (EPDM) were tested before, during and after aging to capture the with respect to application most important of their complex mechanical properties. Exemplary results of these investigations were used to calibrate material models implemented in the commercial finite element software ABAQUS/Standard®. The finite element model already presented in previous works uses a sequential temperature displacement coupling. The calculated compression stress relaxation (CSR) and compression set (CS) values do satisfactorily match the experimental results. In many investigations performed at BAM both values (CSR and CS) were identified as key indicators of elastomer's long-term performance. However, the possibility to correlate these equivalent indicators with performance values such as tightness and leakage rate, measurable in the mounted state, is an important goal of our future work. In the presented study the ABAQUS® feature of "pressure penetration" is introduced in the suggested finite element model for this purpose. It provides the possibility to simulate the penetration of a gas into a possible gap between flange and O-ring causing an opening of a leakage path. Three dimensional and axis-symmetric finite element models were generated to represent flat and grooved flanges of different dimensions. The sensitivity of the feature to several input parameters is investigated and the observed behavior of the O-ring is correlated with the results of performed leakage tests. New York, NY, USA American Society of Mechanical Engineers (ASME) 2021 Proceedings of the ASME 2021 Pressure Vessels & Piping Conference (PVP2021) 978-0-7918-8535-2 ASME 2021 Pressure Vessels & Piping Conference (PVP2021) Online meeting 13.07.2021 15.07.2021 1 8 10.1115/PVP2021-61976 2022-03-04 OPUS4-53114 Beitrag zu einem Tagungsband Völzke, Holger; Wolff, Dietmar; Orellana Pérez, Teresa; Herold, Christian; Bollingerfehr, W.; Wunderlich, A.; Prignitz, S. Anforderungen an Behälter für die Endlagerung hochradioaktiver Abfälle in Steinsalz, Tonstein und Kristallingestein Bei der Auswahl eines Standortes für ein Endlager für hochradioaktive Abfälle (Wärme entwickelnde radioaktive Abfälle und ausgediente Brennelemente) in Deutschland werden auf Grundlage des Standortauswahlgesetzes von 2017 die drei potenziellen Wirtsgesteine Steinsalz, Tonstein und Kristallingestein in Betracht gezogen. Die Auswahl eines konkreten Endlagerstandortes steht dabei in engem Zusammenhang mit den für die jeweiligen Wirtsgesteine geeignet erscheinender Endlagersystemen. Zentraler Bestandteil dieser Endlagersysteme sind die Endlagerbehälter, deren Gestaltung und Auslegung maßgeblich die Randbedingungen für die Transport- und Einlagerungstechnik vorgibt und zudem die Nachweise zur Betriebs- und Langzeitsicherheit entscheidend prägt. Daher ist es für die Behälterentwicklung erforderlich, die an Endlagerbehälter zu stellenden Anforderungen systematisch herzuleiten. Auf dieser Grundlage können anforderungsgerechte Endlagerbehälter zielgerichtet für die jeweils zu untersuchenden Endlagerstandorte in unterschiedlichen Wirtsgesteinen entwickelt werden. Dieser Beitrag fasst die wesentlichen Ergebnisse des von BAM und BGE TECHNOLOGY GmbH im Zeitraum 2017 bis 2020 bearbeiteten und vom Bundesministerium für Wirtschaft und Energie (BMWi) geförderten Forschungsvorhabens KoBrA zusammen, die in einem Abschlussbericht und vier zugehörigen Teilberichten umfassend dokumentiert sind. TU Bergakademie Freiberg 2021 Proceedings Tage der Standortauswahl 2021 Tage der Standortauswahl Freiberg, Germany 11.02.2021 12.02.2021 1 10 2021-08-19 OPUS4-53117 Forschungsbericht Herold, Christian; Orellana Pérez, Teresa; Völzke, Holger; Wolff, Dietmar Nationaler und Internationaler Stand zu bereits existierenden Anforderungen und Konzepten für Endlagerbehälter und Zusammenstellung sicherheitsrelevanter Behältereigenschaften; Bericht zum Arbeitspaket 1 des FuE-Verbundvorhabens KoBrA Im hier vorliegenden Bericht wurde im Rahmen einer umfassenden Literaturrecherche der nationale und internationale Stand von Wissenschaft und Technik hinsichtlich Behälterkonzepten und Behälteranforderungen erfasst. Dabei wurde eine umfangreiche Dokumentensammlung zusammengestellt und sortiert, die als Quellenbasis für alle weiteren Arbeiten zur Verfügung steht. Die Auswertung der gesammelten Informationen resultiert in einem Überblick über internationale Behälterentwicklungen sowie einer detaillierten Übersicht über die Behälterkonzepte und die ihnen zugrundeliegenden Anforderungskataloge aus elf fortgeschrittenen Endlagerprogrammen. Berlin Bundesanstalt für Materialforschung und -prüfung (BAM) 2020 1 284 10.2314/KXP:1759195804 2021-09-29 OPUS4-53118 Forschungsbericht Herold, Christian; Völzke, Holger; Orellana Pérez, Teresa; Wolff, Dietmar; Bollingerfehr, W.; Wunderlich, A.; Prignitz, S. Erarbeitung von Vorschlägen für mögliche Behälterkonzepte in den drei potenziellen Wirtsgesteinen Steinsalz, Tonstein und Kristallingestein; Bericht zum Arbeitspaket 4 des FuE Verbundvorhabens KoBrA Dieser Bericht untersucht die im ersten Arbeitspaket ermittelten vorhandenen bzw. entwickelten Behälterkonzepte dahingehend, inwieweit die jeweiligen Behälterfunktionen unter den im zweiten und dritten Arbeitspaket ermittelten Randbedingungen und Einwirkungen den im dritten Arbeitspaket ermittelten Anforderungen an endlagerfähige Behälter in einem deutschen Endlager genügen. Zum anderen sollen, basierend auf den im zweiten Arbeitspaket ermittelten Randbedingungen und den im dritten Arbeitspaket hergeleiteten und zusammengestellten Anforderungen an die Endlagerbehälter, Vorschläge für mögliche generische Endlagerbehälter in den drei potenziellen Wirtsgesteinen Steinsalz, Tonstein und Kristallingestein erarbeitet werden. Die im ersten Arbeitspaket recherchierten Behälterkonzepte, deren Entwicklungslinien und zugrundeliegende Behälteranforderungen bilden hier den Ausgangspunkt für weitergehende Überlegungen hinsichtlich ihrer potenziellen Eignung für ein zukünftiges deutsches Endlager und zur Skizzierung generischer Konzepte für zukünftige Endlagerbehälter. Berlin Bundesanstalt für Materialforschung und -prüfung (BAM) BGE Technology 2020 1 76 10.2314/KXP:1759194123 2021-09-29 OPUS4-53119 Forschungsbericht Herold, Christian; Völzke, Holger; Wolff, Dietmar; Orellana Pérez, Teresa; Bollingerfehr, W.; Wunderlich, A.; Prignitz, S. Herleitung und Zusammenstellung der Anforderungen an Endlagerbehälter für ein HAW-Endlager in den drei potenziellen Wirtsgesteinen Steinsalz, Tonstein und Kristallingestein; Bericht zum Arbeitspaket 3 des FuE Verbundvorhabens KoBrA Der Bericht zum Arbeitspaket 3 baut auf den Ergebnissen der internationalen Recherche (AP1) sowie der Zusammenstellung der Randbedingungen und Beanspruchungsgrößen für die Endlagerbehälter (AP2) auf. Die Anforderungen an die Behälter - regulatorische, betriebliche sowie solche aus der Standortgeologie und den Einwirkungen und Prozessen, denen die Behälter ausgesetzt sind - werden hergeleitet und systematisch dargestellt. Die für das Endlagersystem zu betrachtenden Nutzungsphasen werden aus den regulatorischen Anforderungen hergeleitet und charakterisiert. Die Einwirkungen auf die Behälter in den drei potenziellen Wirtsgesteinen sowie die sich für die Erfüllung der Sicherheitsfunktionen des Behälters als Teil des Endlagersystems ergebenden Behälterfunktionen werden ebenfalls wirtsgesteins- und zeitphasenabhängig betrachtet. Schließlich werden aus den Einwirkungen auf die Behälter und den Anforderungen an die Behälterfunktionen auch quantifizierbare Behälterfunktionen für alle drei potenziellen Wirtsgesteine abgeleitet. Peine BGE Technology Bundesanstalt für Materialforschung und -prüfung (BAM) 2020 1 254 2021-09-29 OPUS4-57093 Beitrag zu einem Tagungsband Weber, Mike; Zaghdoudi, Maha; Brandt, Guido; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Coefficients of Friction in Dependence on Aging State of Elastomers - Experimental Identification and Numerical Simulation of the Experiment Elastomer seals are mounted as barrier seals in lid systems of containers designed for transport and disposal of negligible heat generating radioactive waste and as auxiliary seals in spent fuel storage and transportation casks (dual purpose casks (DPC)). When the behavior of mounted seals under normal and hypothetical accident conditions of disposal and transport is to be simulated, a comprehensive knowledge of their complex mechanical properties at every state of aging is necessary. In previous works, BAM's efforts in experimental investigations on specimen artificially aged at different temperatures and times and the implementation of the found results in finite element material models were presented. Additionally, our approaches to reproduce the aging process itself and to extrapolate the results of artificially accelerated aging to longer times were presented. Numerical simulations have shown that the behavior of the seal during mounting and one-sided pressurizing and the resulting performance values such as leakage rate strongly depend on the coefficient of friction (COF) between flange and seal. The friction coefficient, in turn, depends on the aging state of the elastomer material as several publications suggest (see below). Dynamic COF between an exemplary ethylene propylene diene rubber (EPDM) material and a stainless steel ball were determined by using a self-designed linear oscillation tribometer. Unaged and artificially aged EPDM specimen stored for 30 days and 100 days at a temperature of 150 °C were tested. A stainless steel ball (d=10 mm) is brought in contact with the specimen's surface und loaded by normal forces of 2.5 N, 5 N, 10 N and 20 N. During a reciprocating movement of the EPDM sheet, the horizontal force/friction force is continuously measured, and the COF can be derived. It is well known that friction is a complex phenomenon especially in soft materials. It cannot be excluded that the measured friction force is influenced by additional force components, resulting from the ball's grooving through the elastomer's surface. This force depends on the penetration depth of the ball and on the resistance of the elastomer in its different states of aging. The latter results from microstructural changes i.e., chain scission and additional crosslinking that occur during aging which in turn influence the softening or hardening of the material. A finite element (FE) ABAQUS® model was developed to reproduce the measurement process. It should help to better understand the physical mechanisms and to quantify the percentage of measured forces resulting from real friction on the one hand and forces resulting from unintended side effects that could falsify the result on the other hand. The behavior of the elastomer in its different states of aging is reproduced by a FE material model already presented in previous works of BAM. New York, NY, USA American Society of Mechanical Engineers (ASME) 2022 Proceedings of the ASME 2022 Pressure Vessels & Piping Conference (PVP2022) ASME 2022 Pressure Vessels & Piping Conference (PVP2022) Las Vegas, NV, USA 17.02.2022 22.07.2022 1 8 2023-03-09 OPUS4-36336 Zeitschriftenartikel Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Ageing of HNBR, EPDM and FKM O-rings HNBR, EPDM and FKM O-rings were aged uncompressed and compressed at 75 °C, 100 °C, 125 °C and 150 °C for up to 1 year. HNBR exhibited the strongest ageing effects with high increases of hardness and glass transition temperature. Furthermore, heterogeneous ageing caused by diffusion-limited oxidation effects had a significant influence for HNBR at ageing temperatures of 125 °C and 150 °C. EPDM showed similar property changes as HNBR, but less pronounced. FKM displayed only minor ageing effects. O-rings aged in compression exhibited considerable compression set (CS). CS data was used for a time-temperature shift and resulting master curve construction. Leakage rate measurements showed that O-rings can remain leak tight under static conditions even if material properties have already deteriorated strongly. Heidelberg, Germany Hüthig 2016 KGK - Kautschuk Gummi Kunststoffe 69 4 36 42 2016-06-20 OPUS4-31331 Beitrag zu einem Tagungsband Beckmann, Jörg; von der Ehe, Kerstin; Jaunich, Matthias; Schade, U.; Aziz, E. F.; Wolff, Dietmar Fourier-spektroskopische Untersuchungen im mittleren- und fernen Infrarotbereich an Co-60 bestrahlten und thermisch belasteten ultrahochmolekularen Polyethylen-Proben Fourier-Spektroskopische Untersuchungen von hochmolekularem Polyethylen (HMW-PE) und ultrahochmolekularem Polyethylen (UHMW-PE) im Mittleren - und Fernen Infrarotbereich können Veränderungen der molekularen Strukturen nachweisen, die durch Co60 γ-Strahlung und Rekristallisationsprozesse initiiert werden. UHMW-PE und HMW-PE sind im gewählten IR-Bereich unterscheidbar. Die integrale Absorption der B1u - Gitterschwingungen im Fernen Infrarotbereich (THz-Bereich) ermöglichen die quantitative Beschreibung des Kristallinitätsgrades und dessen Abbau. Die Bildung ungesättigter Vinylengruppen und der Abbau ungesättigter Methylengruppen können im Mittleren Infrarotbereich nachgewiesen werden. Berlin Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) 2014 DGZfP-Berichtsband 148 978-3-940283-61-0 DGZfP-Jahrestagung 2014 Potsdam, Germany 26.05.2014 28.05.2014 1 7 urn:nbn:de:kobv:b43-313317 http://creativecommons.org/licenses/by-nd/3.0/de/ 2016-02-20 OPUS4-30671 Vortrag Wolff, Dietmar BAM - Experience in Safety Evaluation of Spent Fuel Cask Designs for Interim Storage 2014 Workshop PURAM - BAM Workshop PURAM - BAM Paks, Hungary 2014-03-18 2014-03-18 2016-02-20 OPUS4-30672 Vortrag Wolff, Dietmar Bewertung der Langzeiteignung von Zwischenlagerbehältern 2014 4. RAM-Behältersicherheitstage 4. RAM-Behältersicherheitstage Berlin, Germany 2014-03-26 2014-03-27 2016-02-20 OPUS4-31250 Beitrag zu einem Tagungsband Jaunich, Matthias; Wolff, Dietmar An approach to improve the understanding of elastomeric seals in use in storage containers Elastomers are widely used as main sealing materials in Containers for low and intermediate level radioactive waste and as additional component to metal seals in spent fuel and high active waste Containers. They are applied due to their special material properties and easy use [1]. For this application several challenging prerequisites must be met for the essential reliable Operation of the seal. 2014 45th Annual meeting on nuclear technology (Proceedings) 978-3-926956-99-6 45th Annual meeting on nuclear technology Frankfurt, Germany 06.05.2014 08.05.2014 1 4 2016-02-20 OPUS4-30227 Beitrag zu einem Tagungsband Weber, Mike; Zencker, Uwe; Wolff, Dietmar; Völzke, Holger; Herbrich, Uwe; Nagelschmidt, Sven Numerical analysis of cask accident scenarios in storage facilities Existing spent nuclear fuel (SF) and high active waste (HAW) management policies and practices worldwide are the result of past presumptions that sufficient reprocessing and/or disposal capacity would be available in the near term. Consequently, in the past many countries have developed specific solutions for different periods of time due to their individual national nuclear policies. In Germany the concept of dry interim storage in dual purpose metal casks before disposal is being pursued for SF and HAW management and transport and storage licenses have been issued accordingly. The current operation licenses for existing storage facilities have been granted for a storage period of up to 40 years. This concept has demonstrated its suitability for over 20 years so far. Relevant safety requirements have been assessed for the short-term as well as for the long-term for site-specific operational and accidental storage conditions. But in the meantime significant delays in the national repository siting procedure occurred which will make extended storage periods necessary in the future. 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 H, Paper 202, 1 9 2016-02-20 OPUS4-32072 Beitrag zu einem Tagungsband Wolff, Dietmar; Jaunich, Matthias; Probst, Ulrich; Nagelschmidt, Sven Understanding the long-term behavior of sealing systems and neutron shielding material for extended dry cask storage In Germany, the concept of dry interim storage in dual purpose metal casks before disposal is being pursued for spent nuclear fuel (SF) and high active waste (HAW) management. However, since there is no repository available today, the initially planned and established dry interim storage license duration of up to 40 years will be too short and its extension will become necessary. For such a storage license extension it is required to assess the long-term performance of SF and all safety related storage system components in order to confirm the viability of extended storage. The main safety relevant components are the thick-walled dual purpose metal casks. These casks consist of a monolithic cask body with integrated neutron shielding components (polymers, e.g. polyethylene) and a monitored double lid barrier system with metal and elastomeric seals. The metal seals of this bolted closure system guarantee the required leak-tightness whereas the elastomeric seals allow for leakage rate measurement of the metal seals. This paper presents an update on running long-term tests on metal seals at different temperatures under static conditions over longer periods of time. In addition, first results of our approach to understand the aging behavior of different elastomeric seals and neutron radiation shielding material polyethylene are discussed. 2014 PSAM 12 - Probabilistic safety assessment and management (Proceedings) PSAM 12 - Probabilistic safety assessment and management Honolulu, Hawaii, USA 22.06.2014 27.06.2014 1 9 2016-02-20 OPUS4-32049 Vortrag Wolff, Dietmar Long-Term behavior of metal and elastomer sealing systems 2014 IAEA - 2nd RCM of CRP on demonstrating performance of spent fuel and related system components during very long term storage IAEA - 2nd RCM of CRP on demonstrating performance of spent fuel and related system components during very long term storage Tokyo, Japan 2014-11-10 2014-11-14 2016-02-20 OPUS4-32050 Vortrag Wolff, Dietmar Long-Term behavior of metallic and elastomeric sealing systems and polymer neutron shielding materials 2014 Workshop on Aging Management Issues Related to Long-Term Dry Spent Nuclear Fuel (SNF) Storage Workshop on Aging Management Issues Related to Long-Term Dry Spent Nuclear Fuel (SNF) Storage Argonne USA 2014-10-15 2014-10-16 2016-02-20 OPUS4-32051 Vortrag Wolff, Dietmar Long-Term behavior of polymer (PE) neutron shielding materials 2014 IAEA - 2nd RCM of CRP on demonstrating performance of spent fuel and related system components during very long term storage IAEA - 2nd RCM of CRP on demonstrating performance of spent fuel and related system components during very long term storage Tokyo, Japan 2014-11-10 2014-11-14 2016-02-20 OPUS4-30242 Beitrag zu einem Tagungsband Wolff, Dietmar; Völzke, Holger; Wille, Frank; Droste, Bernhard Extended storage after long-term storage Existing spent nuclear fuel (SF) and high active waste (HAW) management policies and practices worldwide are the result of past presumptions that sufficient reprocessing and/or disposal capacity would be available in the near term. Consequently, in the past many countries have developed specific solutions for different periods of time due to their individual national nuclear policies. In Germany the concept of dry interim storage in dual purpose metal casks before disposal is being pursued for SF and HAW management and transport and storage licenses have been issued accordingly. The current operation licenses for existing storage facilities have been granted for a storage period of up to 40 years. This concept has demonstrated its suitability for over 20 years so far. Relevant safety requirements haven been assessed for the short-term as well as for the long-term for site-specific operational and accidental storage conditions. But in the meantime significant delays in the national repository siting procedure occured which will make extended storage periods necessary in the future. This paper describes the current situation in Germany with regard to dry cask storage and focuses on current perspectives considering regulatory, technical, and scientific aspects for storage license renewal. Since there is one case of a storage license limitation to only 20 years due to administrative reasons, first experience is currently gathered in case of an expiring storage license. Subsequent license options have been pursued intensively including the extension of the initial storage license as well as shipping all casks to another storage facility considering an extended storage period at that storage facility as well. All safety relevant aspects have to be reviewed on basis of the current state-of-the-art which might be different from the initial safety demonstrations. That includes new safety assessment standards as well as improved knowledge base. Major issues are e.g. improved accident scenario analyses, assessment methods, and consideration of aging effects from previous operation periods. Inspection programs with respect, e.g. to bolts and seals to verify leak-tightness and lid screw pre-stress have been initiated to demonstrate proper cask conditions for extended storage as well as transportation to another storage facility. 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 Paper 184, 1 12 2016-02-20 OPUS4-30377 Beitrag zu einem Tagungsband Jaunich, Matthias; Wolff, Dietmar; Stark, Wolfgang; Völzke, Holger Investigation of elastomer seal behavior for transport and storage packages Rubbers are widely used as main sealing materials for containers for low and intermediate level radioactive waste and as additional component to metal seals in spent fuel and high active waste containers. According to appropriate guidelines and regulations safe enclosure of the radioactive container contents has to be guaranteed for long storage periods as well as down to temperatures of -40 °C for transportation. Therefore the understanding of seal behavior is of high importance. In this paper we focus on the behavior of elastomer seals at low temperatures with regard to poten-tial decrease of leak-tightness. In addition, changes in material properties due to aging effects over long periods of time and their influence on the seal performance is investigated. It is known that material properties of rubbers are strongly temperature dependent. At low tempera-tures this is caused by the rubber-glass transition (abbr. glass transition). During continuous cool-ing, the material changes from rubber-like entropy-elastic to stiff energy-elastic behavior, that al-lows nearly no strain or retraction due to the glass transition. Hence rubbers are normally used above their glass transition but the minimum working temperature limit is not defined precisely. Aging of elastomer seals is important, as possible dynamic loads may have to be considered during the whole interim storage period (so far approved in Germany for up to 40 years) and for transporta-tion after storage. For the investigations, fluorocarbon (FKM) and ethylene-propylene-diene (EPDM) rubbers were selected as they are often used in radioactive waste containers. Some materials were purchased from a commercial seal producer and some materials were compounded and cured at BAM. The elastom-ers where studied by several thermo-analytical methods and compression set to characterize the material behavior at low temperatures. Additionally component tests were performed to determine the breakdown temperature of the sealing function of complete elastomer O-rings. 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 Paper 227, 1 8 2016-02-20 OPUS4-31026 Vortrag Wolff, Dietmar Understanding the Long-Term Behavior of Sealing Systems and Neutron Shielding Material for Extended Dry Cask Storage 2014 PSAM 12 PSAM 12 Honolulu, HI, USA 2014-06-22 2014-06-27 2016-02-20 OPUS4-31028 Vortrag Wolff, Dietmar Safety Aspects of Dry Spent Fuel Storage and Spent Fuel Management 2014 ENC 2014 European Nuclear Conference ENC 2014 European Nuclear Conference Marseille, France 2014-05-11 2014-05-14 2016-02-20 OPUS4-31947 Beitrag zu einem Tagungsband Shirai, K.; Namba, K.; Wataru, M.; Völzke, Holger; Wolff, Dietmar; Probst, Ulrich; Jaunich, Matthias; Schulz, Sebastian Numerical evaluation of the long-term sealing performance of the silver gasket for dual purpose metal cask under high temperature It is important to evaluate the effect of thermal ageing on the sealing performance of metal gaskets under high temperature for long-term usage. Therefore, in order to gain representative data for this kind of metal-sealed lid System, BAM is currently performing laboratory tests of different gasket types with aluminum and silver jackets at three different temperatures under static conditions up to four years so far, using test flanges for gaskets with full scale cross section diameter but much smaller outer diameter. On the other hand, in order to investigate the applicability of the numerical methodology to evaluate the long-term behavior of the metal gaskets, such as a correlation between seal pressure force and holding time, CRIEPI is developing a modeling method including material tests (tensile and creep tests) at high temperature. In this paper, the applicability of the finite element method (ABAQUS) to predict the recovery displacement and residual seal pressure force of the gasket complex was verified by comparing the calculated values with BAM's laboratory test results under the joint research agreement between BAM and CRIEPI. 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 1 8 2016-02-20 OPUS4-31516 Beitrag zu einem Tagungsband Weber, Mike; Zencker, Uwe; Wolff, Dietmar; Völzke, Holger; Herbrich, Uwe; Nagelschmidt, Sven Numerical analysis of cask accident scenarios in storage facilities Mechanical drop test scenarios for Type B (U) packages according to the IAEA regulations have to be carried out onto the so-called "unyielding target" (usually with cask impact limiters) and onto the puncture bar respectively. They are predefined and do not require any further investigation of scenarios that really could happen on transportation routes. Cask accident scenarios in the framework of approval procedures for interim storage sites are derived from a detailed analysis of the handling procedures necessary from arrival of cask at the site to its storing position. In that case, casks are usually handled without impact limiters. Dependent on possible drop heights, drop positions and floor properties, conservative cask accident scenarios are derived for further safety proofs. According to the mechanical assessment concept of the considered approval procedure numerical calculations have to be provided by the applicant to demonstrate mechanical cask safety. Stresses and strains in the cask body as well as in the lid System have to be identified and assessed. Using the example of a 3-mvertical-drop of a transport and storage cask for spent fuel elements onto the floor construction made of damping concrete covered by screed, BAM developed a finite element model. The finite element code ABAQUS/Explicit™ was used. Results of experimental investigations are not available. Therefore parameter studies are necessary to identify the sensitivity of the finite element model to significant Parameters and to verify the finite element models according to the requirements of the Guidelines for the Numerical Safety Analyses for the Approval of Transport and Storage Casks for Radioactive Materials (BAM GGR-008). The paper describes the modeling of the material behavior and attachment of bottom side cask components. Questions concerning the modeling of a crack length limiting reinforcement in the screed layer are discussed. The influence of the mesh density of the screed layer and its strength is considered as well. Finally, the developed finite element model can be used for a numerical safety assessment. It can help to understand the complex mechanisms of the interaction between the cask components and floor construction. WM Symposia, Inc. 2014 WM2014 Conference (Proceedings) 978-0-9836186-3-8 WM2014 Conference Phoenix, Arizona, USA 02.03.2014 06.03.2014 Paper 14541, 1 12 2016-02-20 OPUS4-31572 Zeitschriftenartikel Jaunich, Matthias; Stark, Wolfgang; Wolff, Dietmar Druckverformungsrest bei tiefen Temperaturen Der Druckverformungsrest (DVR) stellt insbesondere für Dichtungsanwendungen eine wichtige Kenngröße zur Beurteilung der Eignung eines Elastomers dar. Er ermöglicht die Einschätzung des zeitabhängigen Rückstellverhaltens eines Werkstoffs nach Deformation. Neben der Prüfung bei erhöhten Temperaturen, zur Beurteilung des Alterungsverhaltens, lässt sich bei der Durchführung bei tiefen Temperaturen die limitierende Einsatztemperatur bestimmen. Die Versuchsdurchführung unterscheidet sich je nach angewandter Norm und kann einen deutlichen Einfluss auf den DVR-Wert haben. Um bei tiefen Temperaturen eine schnelle Aussage zu gestatten, ist eine im Vergleich zu genormten Methoden deutlich schneller durchzuführende, automatisierte Methode entwickelt und mit Standardmethoden verglichen worden. Durch kontinuierliche Messung des Druckverformungsrests kann die Kinetik der Materialrückstellung betrachtet und dadurch ein effizienter Materialvergleich und eine effiziente Materialauswahl ermöglicht werden. Compression set (CS) is especially for sealing applications an important parameter for material selection. It allows an assessment of the time dependent recovery after deformation. In addition to testing at elevated temperatures which aims at the evaluation of the ageing behaviour, testing at low temperatures permits the determination of the low working temperature limit. The test procedure varies depending on the applied standard and can show a significant effect on the CS value. In order to allow a quick statement regarding low temperatures an automated procedure being significantly faster realisable in relation to the standardised methods has been developed and compared with standard procedures. Continuous measurement of the compression set allows evaluating the recovery kinetics and therefore an efficient comparison and selection of materials. Ratingen Gupta 2014 GAK: Gummi, Fasern, Kunststoffe 67 8 487 491 2016-02-20 OPUS4-30235 Beitrag zu einem Tagungsband Botsch, W.; Smalian, S.; Hinterding, P.; Völzke, Holger; Wolff, Dietmar; Kasparek, Eva Maria Dual purpose cask safety evaluation - Expertise in dry storage In Germany dual purpose casks for spent nuclear fuel (SF) or high level radioactive waste (HLW) are used for safe transportation and interim storage. Key safety issues in both fields are the safe enclosure of the radioactive material, the safe removal of decay heat, securing nuclear criticality safety, limitation of radiation exposure to acceptable levels and keeping it as low as reasonable achievable (ALARA principle). Whereas these safety requirements during transportation are ensured by the Type-B(U)-design testing and approval procedure on basis of internationally agreed IAEA (International Atomic Energy Agency) requirements storage licenses are issued on national and site specific safety analyses. This paper presents experiences from recent interim storage safety evaluation and licensing procedures in Germany on basis of a Type-B(U) certified cask designs concerning specific differences from Operation and accident conditions inside the storage facility. The focus is laid on the interaction of cask and building structures with regard to shielding, heat removal and accident analyses including aircraft crash. Basic safety is assured by thick-walled metal casks with monitored double lid Systems. They also reduce radiation to levels where workers can safely operate and maintain the casks inside the storage facility. The storage building e. g. provides additional shielding and protection against extemal hazards depending on the building construction. In addition, the storage building helps to reduce radiation levels at the boundary of the storage site well below regulatory limits given by the German Radiation Protection Ordinance (StrSchV). 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 1 8 2016-02-20 OPUS4-19611 Beitrag zu einem Tagungsband Jaunich, Matthias; Stark, Wolfgang; Wolff, Dietmar Properties of elastomeric seals at low temperature Deutsche Kautschuk-Gesellschaft e.V. 2009 International rubber conference 2009 International rubber conference (IRC 2009) Nürnberg, Germany 2009-06-29 2009-07-02 Poster 23 1 3 2016-02-19 OPUS4-21997 Beitrag zu einem Tagungsband von der Ehe, Kerstin; Jaunich, Matthias; Böhning, Martin; Goering, Harald; Wolff, Dietmar Detection of structural changes of (U)HMW-PE induced by gamma irradiation Halle / Saale Druck-Zuck GmbH 2010 14th International conference "Polymeric materials" - P.2010 (Proceedings) 978-3-86829-282-4 14th International conference "Polymeric materials" Halle (Saale), Germany 2010-09-15 2010-09-17 1 6 2016-02-19 OPUS4-20386 Beitrag zu einem Sammelband Jaunich, Matthias; Stark, Wolfgang; Wolff, Dietmar Messung des Tieftemperaturverhaltens von Elastomer-Dichtungen Technische Universität Chemnitz 2009 TECHNOMER 2009 - 21. Fachtagung über Verarbeitung und Anwendung von Polymeren 978-3-939382-09-6 TECHNOMER 2009 - 21. Fachtagung über Verarbeitung und Anwendung von Polymeren Chemnitz, Deutschland 2009-11-12 2009-11-14 ETV7 1 9 2016-02-19 OPUS4-21914 Zeitschriftenartikel Jaunich, Matthias; Stark, Wolfgang; Wolff, Dietmar A new method to evaluate the low temperature function of rubber sealing materials A new method for the evaluation of the low temperature properties of rubber materials is presented. The method emulates the standardized compression set measurement, which is frequently used for sealing materials, but can be performed within a considerably shorter time. The results are compared with the standard test and found to be qualitatively the same. Slight differences are discussed on the basis of the differences in the measurement procedures. Further data evaluation is done by fitting functions to describe the material behaviour. Amsterdam [u.a.] Elsevier Science 2010 Polymer testing 29 7 815 823 10.1016/j.polymertesting.2010.07.006 2016-02-19 OPUS4-23890 Zeitschriftenartikel Erhard, Anton; Völzke, Holger; Probst, Ulrich; Wolff, Dietmar Aging management for long-term interim storage casks The aging management system for the mechanical components of nuclear power plants (NPPs) must be established and used by the licensee in such a way that the quality of safety relevant components is guaranteed for the completely designed lifetime of the NPP. This demands an extensive plant life management with special emphases on the knowledge of the degradation in material properties. The basic safety concept in Germany observes this circumstance. Lifetime extension of the German NPPs is an aim of the current valid coalition agreement of the German government. Operational extension of interim storage facilities requires, in comparison to the aging management system for NPP, an aging management system adapted to the Special circumstances of spent fuel storage casks. Extension of interim storage periods for spent fuel casks beyond the designed lifetime requires, in comparison to the components of an NPP, an increasing knowledge of material degradation with potential impact on cask integrity, e.g. leak tightness. Dry interim storage in Germany has been approved for 40 years. After that time, according to the present strategy, a final repository should be available. However, until now, such a final facility still does not exist, and the German exploration and licensing process is heavily delayed. Currently, discussions are continuing regarding further exploration of the Gorleben salt mine. There is willingness to overcome this situation that is clearly described in the available coalition agreement of the federal government. Anyway, however, the prediction is viewed; a repository for heat generating radioactive waste in Germany will not be available in the near future and may not be available when first storage facilities and casks reach their 40 years of approved lifetime, which will occur in ~25 years starting from now. Therefore, the question must be asked: what has to be done with the existing storage casks in the interim facilities? May these casks be fit for continued use, with an extension of the storage period? One option is to have an aging management system, which creates enough information about the technical condition of safety relevant cask properties. This is the basis for safety evaluation for extended storage periods. In the present paper, possible aging mechanisms for high level waste storage casks are discussed, as well as the influence of the time dependent changes of the component properties. Ashford Ramtrans Publ. 2011 Packaging, transport, storage & security of radioactive materials (RAMTRANS) 22 1 46 53 10.1179/1746510910Y.0000000013 2016-02-19 OPUS4-23887 Beitrag zu einem Tagungsband Jaunich, Matthias; von der Ehe, Kerstin; Wolff, Dietmar; Völzke, Holger; Stark, Wolfgang Understanding the low temperature properties of rubber seals Rubbers are widely used as main sealing materials for containers for low and intermediate level radioactive waste and as additional component to metal seals in spent fuel and high active waste containers. The save encapsulation of the radioactive container inventory has to be guaranteed according to legislation and appropriate guidelines for long term storage periods as well as down to temperatures of -40 °C during transport. Therefore the understanding of failure mechanisms that lead to leakage at low temperatures is of high importance. It is known that the material properties of rubbers are strongly temperature dependent. At low temperatures this is caused by the rubber-glass transition (abbr. glass transition). During continuous cooling the material changes from rubber-like entropy-elastic to stiff energy-elastic behaviour, that allows nearly no strain or retraction, due to the glass transition. Hence rubbers are normally used above their glass transition but the minimum working temperature limit is not defined precisely, what can cause problems during application. Therefore the lower operation temperature limit of rubber seals should be determined in dependence of the material properties. The results of Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) are combined with the results of standardized measurements as the compression set according to ISO 815. To reduce the test time of the standard tests a faster technique was developed. Additionally, the breakdown temperature of the sealing function of complete O-ring seals is measured in a component test setup to compare it with the results of the other tests. The experimental setup is capable of measuring the leakage rate at low temperatures by the pressure rise method. A fluorocarbon rubber (FKM) was selected for this investigation as it is often used for radioactive waste containers. Some materials (seals and test sheets) were purchased from a commercial seal producer and some materials were compounded and cured at BAM in form of rubber sheets. 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 7 (Session T41 / Paper 169) 2016-02-19 OPUS4-23907 Beitrag zu einem Tagungsband Erhard, Anton; Völzke, Holger; Probst, Ulrich; Wolff, Dietmar Ageing management for long term interim storage casks 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 17 (Tuesday/T20/61) 2016-02-19 OPUS4-24015 Zeitschriftenartikel Jaunich, Matthias; von der Ehe, Kerstin; Wolff, Dietmar; Völzke, Holger; Stark, Wolfgang Understanding low temperature properties of elastomer seals Elastomers are widely used as the main sealing materials for containers for low and intermediate level radioactive waste and as an additional component to metal seals in spent fuel and high active waste containers. The safe encapsulation of the radioactive container inventory has to be guaranteed according to regulation and appropriate guidelines for long term storage periods as well as for temperatures as low as -40°C during transport. Therefore, the understanding of failure mechanisms that lead to leakage at low temperatures is of high importance. It is known that the material properties of elastomers are strongly temperature dependent. At low temperatures, this is caused by the rubber-glass transition (abbreviated: glass transition). During continuous cooling, the material changes from a rubber-like entropy elastic to a stiff energy elastic behaviour, which allows nearly no strain or retraction. Hence, rubbers are normally used above their glass transition, but the minimum working temperature limit is not defined precisely; this can cause problems during the above noted applications. Therefore, the lower operation temperature limit of elastomer seals must be determined in dependence of the material properties. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) are combined with standardised measurements to determine the compression set according to ISO 815. To reduce the test time of the standard tests, a faster technique than normally used was developed. Additionally, the breakdown temperature of the sealing function of complete O ring seals was measured in a component test set-up to compare it with the results of the other tests. The experimental set-up is capable of measuring the leakage rate at low temperatures by the pressure rise method. A fluorocarbon rubber (FKM) was selected for this investigation as it is often used for radioactive waste containers. The materials (seals and test sheets) were purchased from a commercial seal producer. Ashford Ramtrans Publ. 2011 Packaging, transport, storage & security of radioactive materials (RAMTRANS) 22 2 83 88 10.1179/1746510911Y.0000000004 2016-02-19 OPUS4-24172 Beitrag zu einem Tagungsband Wille, Frank; Wolff, Dietmar; Droste, Bernhard; Völzke, Holger Requirements for transport packages after interim storage In Germany the concept of dry interim storage of spent fuel and vitrified high active waste in dual purpose metal casks is implemented (currently for periods of up to 40 years). The casks being used have an approved package design in accordance with the international transport regulations. The license for dry storage is granted on the German Atomic Energy Act with respect to the guidelines of the German Reactor Safety Commission for dry interim storage of spent fuel. Currently part of the assessment process of the cask design for transport on public routes is to evaluate the suitability of the used materials with respect to their properties and their compatibility for possible transport periods. For transport on public routes during or after long term interim storage periods, it has to be ensured that the transport and storage casks fulfill the specifications of the transport approval or other sufficient properties which satisfy the proofs for the compliance of the safety objectives at that time. This paper describes the state-of-the-art technology in Germany and points out arising prospective challenges and which related questions have to be answered in future. Present research and knowledge concerning the long term behavior of transport and storage cask components (such as gaskets and shielding components) have to be consulted as well as experiences from interim cask storage operations. Challenges in the safety assessment are therefore i.e. the behavior of aged metal and elastomeric gaskets under IAEA test conditions to ensure that the results of drop tests can be transferred to the compliance of the safety objectives at the time of transport after the interim storage period (aged package). Assessment methods for the material compatibility, the behavior of fuel assemblies and the aging behavior of shielding parts (e. g. influence of radiation) are further issues as well. Institute of Nuclear Materials Management (INMM) 2011 52nd INMM Annual meeting (Proceedings) 52nd INMM Annual meeting Palm Desert, CA, USA 17.07.2011 21.07.2011 1 9 2016-02-19 OPUS4-24173 Beitrag zu einem Tagungsband Völzke, Holger; Probst, Ulrich; Wolff, Dietmar; Nagelschmidt, Sven; Schulz, Sebastian Investigations on the long term behavior of metal seals for spent fuel storage casks Metal seals are in common use as an essential component for the leak tight closure of transport and storage casks for spent fuel and vitrified high active waste from reprocessing. They are placed between the massive monolithic cask body made of ductile cast iron or forged steel and the primary and secondary lids, which are fixed with screws around the lid circumference, in order to ensure long term safe enclosure of the radioactive cask inventory. Hereby, long term reliable pressure forces in combination with a tight surface contact are as important as well maintained seal and surface qualities and dry and clean conditions during seal assembly and operation. A few years ago BAM started systematic investigation on the long term seal behavior with re-spect to longer storage periods and seal behavior in accidental cask scenarios with dynamic de-formations of the seal groove geometry or short term drop in pressure force up to lid lifting. BAM has developed test flanges for seals with full scale cross section diameter but much small-er outer diameter to gain representative data for metal-sealed lid systems. They are placed in appropriate testing machines for relevant mechanical loading under static and dynamic condi-tions with the ability to measure the standard helium leakage rate continuously during each test phase. This paper focuses on BAM long term tests of different seal types with aluminum and silver jackets at three different temperatures of +20°C, +100°C and +150°C under static conditions over longer periods of time. Due to creeping effects, a reduction of the pressure force does ap-pear during loading and unloading depending on prior holding times. So far, test results of up to 2 years indicate a clear correlation between seal pressure forces and holding time, temperature and seal type allowing for extrapolating to much longer periods of time. The paper presents basic correlations, test and evaluation procedures as well as important provisional results and gives an outlook on further investigations. Institute of Nuclear Materials Management (INMM) 2011 52nd INMM Annual meeting (Proceedings) 52nd INMM Annual meeting Palm Desert, CA, USA 17.07.2011 21.07.2011 1 9 2016-02-19 OPUS4-23422 Zeitschriftenartikel Jaunich, Matthias; Stark, Wolfgang; Wolff, Dietmar Low temperature properties of rubber seals Rubber is widely used as sealing material in various applications. In many fields the sealing function at low temperatures is necessary. Therefore the understanding of failure mechanisms is of high importance. Rubbers are normally used above their glass-rubber transition region but the minimum working temperature limit is not defined precisely. Therefore the lower operation temperature limit of rubber seals should be determined in dependence of the material properties. The results of Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) are combined with the results of the standardized compression set according to ISO 815 respectively a modified test using the DMA equipment. Heidelberg Hüthig Deutsche Kautschuk-Gesellschaft 2011 Kautschuk, Gummi, Kunststoffe (KGK) 03 52 55 2016-02-19 OPUS4-23651 Beitrag zu einem Tagungsband Völzke, Holger; Wolff, Dietmar Safety aspects of long dry interim cask storage of spent fuel in Germany Dry cask storage of spent fuel and high active waste front reprocessing is licensed and established in Germany for up to 40years so far. About 10years ago, the strategy has been shifted from centralized storage using facilities in Ahaus and Gorleben to cit-site storage facilities in Order to avoid immediate cask shipping from nuclear power plants. At present, several hundred casks are stored safeiy and without any major problem. BAM is highly involved in cask specific safety evaluations within the scope of licensing procedures as well as of quality assurance procedures during cask fabrication, loading and storage. A major prerequisite for any cask storage license is a valid transport Type B license. Subsequently, cask transportability has to be ensured at any point during the entire storage period. So far, this requirement is met by continuous maintenance of the Type B license. Anyhow, IAEA Type B regulations do not consider permanently loaded storage casks that have the sole purpose of being finally shipped öfter decades of storage inducing ageing effects. No transport safety demonstration has to be performed on aged cask components. American nuclear society (ANS) 2011 IHLRWM 2011 - International high-level radioactive waste management conference (Proceedings) International high-level radioactive waste management conference (IHLRWMC 2011) Albuquerque, NM, USA 10.04.2011 14.04.2011 712 719 2016-02-19 OPUS4-19148 Vortrag Wolff, Dietmar Beurteilung der Langzeitbeständigkeit von Behälter-Dichtsystemen 2009 1. RAM-Behältersicherheitstage 2009 1. RAM-Behältersicherheitstage 2009 Berlin-Horstwalde, Germany 2009-03-26 2009-03-27 2016-02-19 OPUS4-23708 Beitrag zu einem Tagungsband Kasparek, Eva Maria; Scheidemann, Robert; Zencker, Uwe; Wolff, Dietmar; Völzke, Holger Effect of dynamic loading on compressional behavior of damping concrete In drop test scenarios related to assessing and licensing the storage procedure of spent fuel and high active waste, the casks under examination are generally not equipped with impact limiters. Hence, the extent of mechanical stresses in case of an assumed handling accident is largely affected by the ground properties of the reception hall floor in the specific storage facility. Unlike conventional brittle foundation materials, damping concrete performs quite well in such applications as it features high stiffness as well as high energy absorption due to the filler pore volume. However, its damping ability is not sufficiently exploited in current finite element (FE) calculations due to a lack of advanced material models for simulating its impact response. An implementation of qualified concepts that account for plastic, strain rate dependent behavior requires additional information that has to be provided by systematic test series. BAM recently started a research project to generate such data, subsequently to develop and to improve numerical methods for the analysis of impact limiters and damping foundation material and thus to optimize safety assessment tools for the design of transport and storage casks. A major part of this research concerns dynamic compression tests of variably shaped specimens conducted at a servo hydraulic 1MN impact testing machine as well as at a BAM facility for guided drop tests. This presentation focuses 100mm damping concrete cubes deformed vertically at constant rates under different constraint conditions. For example, a special fitting jig was constructed to subject the specimens to multi-axial loading. Thereby a deformation of 60% could be applied. Simulation was conducted by FE code ABAQUS™ based on material models “Concrete damaged plasticity” and “Crushable foam” which both allow defining rate sensitive nonlinear stress-strain relations in compression beyond the classic metal plasticity approach. 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 (Thursday-T40-114) 2016-02-19 OPUS4-23709 Beitrag zu einem Tagungsband Kasparek, Eva Maria; Völzke, Holger; Scheidemann, Robert; Zencker, Uwe; Wolff, Dietmar Experimentelle und numerische Untersuchungen von stoßdämpfenden Werkstoffen für Behälter zur Entsorgung radioaktiver Stoffe Die mechanische Beanspruchung von Transport- und Lagerbehältern für radioaktive Stoffe gemäß den durch die IAEA vorgegebenen Prüfszenarien oder bei Unfällen, die während der Handhabung in einer kerntechnischen Anlage auftreten können, wird maßgeblich durch das Design der Stoßdämpfer und die Eigenschaften des jeweiligen Untergrundes beeinflusst. Da der Nachweis der Behälterintegrität und -dichtheit häufig an numerische Simulationen gekoppelt ist, sind für die sicherheitstechnische Auslegung der Konstruktion zuverlässige Informationen über das Energieabsorptionsvermögen der Werkstoffe und eine geeignete Umsetzung dieser Daten in FEM - Programme erforderlich. Die im Rahmen von Falluntersuchungen bei der BAM festgestellten, teilweise erheblichen Abweichungen zwischen experimentellen und berechneten Größen sind entsprechend darauf zurückzuführen, dass die zur Verfügung stehenden numerischen Verfahren das komplexe Verhalten der stoßdämpfenden Strukturen nicht ausreichend präzise wiedergeben. Hiervon besonders betroffen sind Bauteile aus Holz und Polyurethan-Schaum (PU-Schaum), die zur Konstruktion von Behälterstoßdämpfern für die Transportkonfiguration eingesetzt werden, sowie Dämpferbeton, der in ausgewählten Bereichen im Fundament von Standort-Zwischenlagern eingebaut wird. Um die zugehörigen Materialmodelle weiter zu entwickeln und die dafür erforderliche Datenbasis zu schaffen, hat die BAM vor knapp zwei Jahren das vom BMBF geförderte Forschungsvorhaben ENREA (Entwicklung rechnerischer Analysemethoden für stoßdämpfende Strukturen beim Anprall oder Absturz von Abfallgebinden) gestartet. Wesentlicher Bestandteil ist ein systematisches Versuchsprogramm, bei dem die drei genannten Werkstoffe statisch und dynamisch hohen Druckbelastungen ausgesetzt werden. Relevante Versuchsparameter sind, neben der Dehnrate, die Temperatur und Lagerungsbedingungen sowie die Orientierung des Werkstoffes hinsichtlich der Belastungsrichtung. Dieser Beitrag präsentiert die wichtigsten Ergebnisse aus der ersten Versuchsphase, die durch weggesteuerte Versuche mit konstanten Prüfgeschwindigkeiten von 0,02 mm/s und 3000 mm/s gekennzeichnet ist. Darüber hinaus wird die Verwertung dieser Daten zur Anpassung von Materialmodellen auf der Grundlage von Nachrechnungen gezeigt, wobei die Möglichkeiten und Grenzen der verwendeten Konzepte Umrissen werden. Aufgrund des Umfangs, den die Versuche mit Holzwerkstoffen einnehmen, und des erforderlichen Aufwandes für die numerische Modellierung werden die entsprechenden Maßnahmen und Ergebnisse in einem eigenständigen Beitrag auf der KONTEC vorgestellt. Kerntechnische Gesellschaft e.V. 2011 KONTEC 2011 - 10. Internationales Symposium "Konditionierung radioaktiver Betriebs- und Stilllegungsabfälle" (Proceedings) KONTEC 2011 - 10. Internationales Symposium "Konditionierung radioaktiver Betriebs- und Stilllegungsabfälle" Dresden, Germany 06.04.2011 08.04.2011 453 458 2016-02-19 OPUS4-38039 Beitrag zu einem Tagungsband Nagelschmidt, Sven; Probst, Ulrich; Völzke, Holger; Wolff, Dietmar Long-term investigations of metal seals for storage casks of radioctive materials The Bundesanstalt für Materialforschung und -prüfung (BAM) is a federal institute for materials research and testing in Germany and has been involved in the qualification and safety evaluation procedures of metal seals from the early beginning of the interim storage licensing procedures for radioactive materials, stored in dual purpose casks. Regarding this subject, BAM investigates the long-term behavior of metal seals under the influence of temperature using experimental data and analytical approaches. The development of numerical models is in progress as well. Systematic experimental investigations performed by BAM indicate a continuous decrease of the remaining seal force and the usable resilience considering the leak tightness. Hence, there is a fundamental interest of describing time and temperature dependency to gain predictable values for the long-term behavior and to achieve reliable results with help of short-term tests. The paper gives an overview about the sealing principle, test program and test results of metal seals of the type HELICOFLEX® HN200. The aging effect, respectively the long-term behavior in dependency of time and temperature, are introduced for two different outer liner materials, aluminum and silver. American society of mechanical engineers (ASME) 2016 Pressure Vessels and Piping Conference (PVP) - ASME Conference Proceedings 7 978-0-7918-5045-9 PVP ASME Conference Vancouver, Canada 17.07.2016 21.07.2016 63596-1 63596-5 2016-11-30 OPUS4-38012 Zeitschriftenartikel Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Revealing effects of chain scission during ageing of EPDM rubber using relaxation and recovery experiment Both chain scission and crosslinking reactions occur during ageing of EPDM rubber. However, with many conventional polymer analysis methods such as hardness and DMA, it is hardly possible to obtain information about the contribution of each reaction type to the measured data. For example, hardness and Tg both increase during ageing of EPDM, indicating crosslinking during ageing, but it is not clear whether this is partly counterbalanced by chain scission reactions which would lower hardness and Tg. An indication that chain scission reactions probably counteract the hardness or Tg increase by crosslinking is given by Compression Set (CS) measurements. CS exhibits a higher change than hardness or Tg, as CS increases additively through both chain scission and crosslinking reactions. In order to elucidate the share of chain scission reactions in the total degradation, a method testing relaxation and recovery behaviour using DMA equipment was applied. The method revealed the strong influence of chain scissions, leading to more pronounced relaxation and higher residual strain after compression. Elsevier Ltd. 2016 Polymer Testing 56 261 268 10.1016/j.polymertesting.2016.10.026 2016-11-01 OPUS4-38014 Beitrag zu einem Tagungsband Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Influence of Ageing on Sealability of HNBR, EPDM and FKM O-rings At BAM, which is the federal institute for materials research and testing in Germany, it is one of our tasks to evaluate the safety of casks designed for transport and/or storage of radioactive material. This includes assessment of elastomeric seals applied in the containers. Besides examining the low-temperature behaviour and irradiation effects of elastomeric seals, it is our goal to evaluate the service lifetime of the seals with regard to the requirements for long-term safety (40 years and more) of the containers. Therefore, we started an accelerated ageing programme with selected rubbers often used for seals (HNBR, EPDM and FKM) which are aged at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) up to 1 year. In order to assess sealability, O-rings are aged in compression by 25 % (corresponding to the compression during service) between plates as well as in flanges that allow leakage rate measurements. For comparison, uncompressed O-rings are aged as well. Further methods characterising seal performance are compression stress relaxation (CSR) reflecting the loss of sealing force of a compressed seal over time, and compression set (CS) which represents the recovery behaviour of a seal after release from compression. Additionally, hardness is measured for information about the change of mechanical properties. The experimental results indicate that while hardness, CSR and CS show considerable degradation effects, the leakage rate stays constant or even decreases until shrinkage and the loss of resilience of the aged seal leads to the formation of a leakage path. This indicates that static leakage rate, which is the only available direct seal performance criterion, has only limited sensitivity for the degradation of the seal material. VDMA 2016 International Sealing Conference 2016 2016 978-3-8163-0674-9 International Sealing Conference Stuttgart, Germany 12.10.2016 13.10.2016 551 563 2016-11-01 OPUS4-34857 Vortrag Wolff, Dietmar Zentrale Koordinierungsstelle für Informationen zur Behälterabfertigung (KOBAF) - Erfahrungen und Perspektiven 2015 7. Symposium Lagerung und Transport radioaktiver Stoffe 7. Symposium Lagerung und Transport radioaktiver Stoffe Hannover 2015-11-25 2016-11-26 2016-02-20 OPUS4-32151 Beitrag zu einem Tagungsband Jaunich, Matthias; Wolff, Dietmar Untersuchungen an Elastomerdichtungen - Tieftemperatur und Alterung Ziel unserer Arbeit ist es, den sicheren Einschluss von gefährlichen Gütern in entsprechenden Verpackungen (z.B. Behälter für radioaktive Stoffe) unter verschiedenen Umgebungsbedingungen und über lange Zeiten sicher zu stellen bzw. die Materialauswahl entsprechend zu steuern. Aufgrund ihrer einfachen und zuverlässigen Anwendung werden Elastomere für viele Dichtungsaufgaben eingesetzt. In vielen Anwendungsbereichen wie z.B. Verkehr, Luftfahrt und Verfahrenstechnik können während des Einsatzes tiefe Temperaturen auftreten, bei denen die Funktionsfähigkeit der Dichtung erhalten bleiben muss. Daher ist die Untersuchung des Verhaltens von Elastomerdichtungen bei tiefen Temperaturen wichtig, um ihren Temperatureinsatzbereich nach unten abzugrenzen und dadurch einen verlässlichen Betrieb zu sichern. Dazu wurden umfangreiche Untersuchungen durchgeführt, auf deren Ergebnisse hier kurz eingegangen werden soll. Bei allen Anwendungen ist die Frage nach der Lebenszeit einer Dichtung entscheidend für z.B. Austauschintervalle oder Wartung. Besondere Bedeutung hat die Lebensdauer allerdings bei Anwendungen, in denen ein Austausch der Dichtung nicht möglich ist. Hier kann die Dichtung über die Lebensdauer des Gesamtsystems entscheiden. Daher ist eine verlässliche Abschätzung der Lebensdauer für diese Anwendungen relevant. Dazu ist eine umfangreiche Datenbasis erforderlich. Entsprechende Arbeiten, die gerade begonnenen worden sind, sollen ergänzend vorgestellt werden. Erste konkrete Ergebnisse werden im Vortrag vorgestellt. Hochschule Merseburg 2014 PolyMerTec 14 PolyMerTec 14 Merseburg, Germany 25.06.2014 27.06.2014 313 318 2016-02-20 OPUS4-35104 misc Völzke, Holger; Wolff, Dietmar; Kasparek, Eva Maria Beitrag zu den Anforderungen an die Beschaffenheit von Endlagerbehältern hinsichtlich ihrer Rückholbarkeit und Bergbarkeit Die Bundesanstalt für Materialforschung und -prüfung (BAM) wurde von der AG 3 der Kommission Lagerung hoch radioaktiver Abfallstoffe gebeten, Anforderungen an Behälter für die Endlagerung hoch radioaktiver Abfallstoffe im Hinblick auf ih-re Rückholbarkeit während des Endlagerbetriebes und ihre Bergbarkeit nach Ver-schluss des Endlagers über einen Zeitraum von 500 (bis 1.000 ?) Jahren darzu-stellen. Die BAM kommt diesem Wunsch auf der Grundlage ihrer langjährigen Er-fahrungen und Fachkenntnisse auf den Gebieten der Bauartprüfung und der si-cherheitstechnischen Begutachtung von Transport- und Lagerbehältern für radio-aktive Stoffe nach. 2015 Kommission Lagerung hoch radioaktiver Abfallstoffe gemäß § 3 Standortauswahlgesetz, Arbeitsgruppe 3 Entscheidungskriterien sowie Kriterien für Fehlerkorrekturen, 14. Sitzung am 24.11.2015 (K-Drs./AG3-47) 1 12 2016-02-20 OPUS4-33253 Beitrag zu einem Tagungsband Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Aging of elastomeric seals for storage casks Elastomeric seals are used in many containers, including casks for radioactive waste. However, like all polymers, elastomers are prone to aging, which leads to a loss of sealing force and the ability for recovery which can ultimately result in leakage. Therefore it is important to be able to define an end-of-lifetime criterion and to judge the lifetime of elastomeric seals. For this reason, we started an aging program on three kinds of rubbers (HNBR, EPDM, FKM), monitoring the change of properties at four different aging temperatures over extended periods up to five years. The measured data is used for lifetime prediction by applying a suitable model. WM Symposia, Inc. 2015 WM2015 Conference (Proceedings) 978-0-9828171-4-8 WM2015 Conference Phoenix, Arizona, USA 15.03.2015 19.03.2015 15080, 1 12 2016-02-20 OPUS4-33254 Beitrag zu einem Tagungsband von der Ehe, Kerstin; Kömmling, Anja; Wolff, Dietmar Neutron radiation shielding material polyethylene: consequences of gamma irradiation High and ultra-high molecular weight polyethylenes are high performance materials, which are predestined for a wide range of applications due to characteristics like high density, low weight, good dimensional stability, high chemical resistance, and high hydrogen content. These polymers are used in two demanding areas: as implant material in medical technology (only ultra-high molecular weight polyethylenes) and as a component for neutron shielding purposes in casks for storage and transport of radioactive waste. In the medical field (joint replacements) as well as during neutron radiation shielding application, high and ultra-high molecular weight polyethylenes are exposed to gamma irradiation: in the first case requested as sterilization process and for surface-crosslinking and in the second case existing as a side effect of inserting the radioactive material in the cask. Given that polyethylene as shielding material has to withstand any type of degradation affecting safety relevant aspects to be applicable for long-term radiation shielding purposes for instance over a period of 40 years, the durability of the material is of special interest. High molecular weight polyethylene (HMW-PE; LUPOLEN 5261Z; Lyondell Basell) and ultra-high molecular weight polyethylene (UHMW-PE; GUR 4120; Ticona) were subjected to gamma radiation and afterwards thermally treated. The gamma doses used are in the range of 50 to 600 kGy and irradiation takes place at RT using a Co-60 source. The planned thermal treatment will take place at a temperature of 125 °C for periods of minimum 30 days and maximum of five years. With the applied conventional analytical techniques it is possible to detect structural changes of both types of polyethylene induced by gamma irradiation and certainly of thermal treatment. Through gamma irradiation melting temperature, crystallinity, and density, respectively increased. Furthermore both polyethylenes get oxidized and cross-linked. With regard to the special application as neutron radiation shielding material in casks for storage and transport of radioactive materials, the impact of irradiation lead to changes of material properties. A consolidated view indicates that the detected changes of the irradiated (U)HMW-PE are not safety relevant for long-term neutron radiation shielding purposes over a period of 40 years in Germany. WM Symposia, Inc. 2015 WM2015 Conference (Proceedings) 978-0-9828171-4-8 WM2015 Conference Phoenix, Arizona, USA 15.03.2015 19.03.2015 15062, 1 10 2016-02-20 OPUS4-32411 Zeitschriftenartikel Stoycheva, V.; Goering, Harald; Wolff, Dietmar; Herzog, M. Bestimmung der Kohäsionsenergie- und Vernetzungsdichte von Polymeren mit Hilfe von Quellungsmessungen Bei der Abschätzung der Beständigkeit von Kunststoffen gegenüber niedermolekularen Flüssigkeiten ist die Kohäsionsenergiedichte CED ein wichtiger Parameter auf molekularer Ebene. Die Vernetzungsdichte ν eines polymeren Festkörpers bildet hierbei einen bedeutsamen Kennwert, der darüber hinaus neben der Löslichkeit wichtige Eigenschaften wie thermische Stabilität und Steifigkeit des Materials charakterisiert. Für die experimentelle Bestimmung von CED und ν eignet sich die Untersuchung des Quellverhaltens in unterschiedlichen Lösungsmitteln. Es werden zwei Messmethoden miteinander verglichen und die Ergebnisse unter Berücksichtigung des molekularen Aufbaus von Proben aus Polyurethan (PU) und hochmolekularem - (HMWPE) und ultrahochmolekularem Polyethylen (UHMWPE) diskutiert. Zum Verständnis des Quellverhaltens dieser Polymerproben in niedermolekularen Lösungsmitteln werden neben den Messergebnissen Literaturdaten zu Grunde gelegt. Berlin News & Media 2014 Wissenschaftliche Beiträge / Technische Hochschule Wildau (FH) 18 77 84 urn:nbn:de:kobv:526-opus4-3372 http://creativecommons.org/licenses/by-nc-nd/3.0/de/deed.de 2016-02-20 OPUS4-32699 Beitrag zu einem Tagungsband Beckmann, Jörg; Schade, U.; von der Ehe, Kerstin; Jaunich, Matthias; Wolff, Dietmar; Aziz, E. F. THz and Mid IR Fourier transform spectroscopy on polyethylene irradiated with Gamma- Co60 radiation THz and mid IR spectroscopy of high molecular PE (HMW) and ultra high molecular PE (UHMW) reveals modifications of the molecular structure induced by γ-Co60 radiation. UHMW-PE and HMW-PE can be distinguished. The integral absorption in the B1u THz-region can quantitatively describe the amorphization of crystallinity. The formation of trans vinylene unsaturations and the decay of vinyl can be followed by mid IR spectroscopy 2014 IRMMW-THz 2014 - 39th International conference on infrared, millimeter, and terahertz waves 978-1-4799-3877-3 IRMMW-THz 2014 - 39th International conference on infrared, millimeter, and terahertz waves Tucson, Arizona, USA 14.09.2014 19.09.2014 IEEE Catalog No.: CFP14IMM-ART 1 2 10.1109/IRMMW-THz.2014.6956355 2016-02-20 OPUS4-32326 Beitrag zu einem Tagungsband Jaunich, Matthias; Wolff, Dietmar Low temperature properties of rubber seals - influence of gamma irradiation Rubbers are widely used as sealing material in various applications. In many fields, the function of seal materials at low temperatures is required. Therefore the understanding of failure mechanisms that lead to leakage at low temperatures is of high importance. Deutsches Institut für Kautschuktechnologie e.V. 2014 11th Fall rubber colloquium 978-3981407624 1 7 2016-02-20 OPUS4-32327 Zeitschriftenartikel Völzke, Holger; Wolff, Dietmar; Probst, Ulrich; Nagelschmidt, Sven; Schulz, Sebastian Long term performance of metal seals for transport and storage casks Dual purpose casks for the transportation and storage of spent nuclear fuel and other radioactive materials require very high leak tightness of lid closure systems under accident conditions as well as in the long term to prevent activity release. For that purpose metal seals of specific types with an inner helical spring and outer metal liners are widely used and have shown their excellent performance if certain quality assurance requirements for fabrication and assembling are satisfied. Well defined surface roughness, clean and dry inert conditions are therefore essential. No seal failure in a loaded cask happened under these conditions until today. Nevertheless, the considered and licensed operation period is limited and all safety assessments have been performed and approved for this period of time which is 40 years in Germany so far. However, in the meantime longer storage periods might be necessary for the future and therefore additional material data will be required. BAM is involved in the qualification and evaluation procedures of those seals from the early beginning. Because long term tests are always time consuming BAM has early decided to perform additional tests with specific test seal configurations to gain a better understanding of the long term behaviour with regard to seal pressure force, leakage rate and useable resilience which is safety relevant mainly in case of accidental mechanical loads inside a storage facility or during a subsequent transport. Main test parameters are the material of the outer seal jacket (silver or aluminium) and the temperature. This paper presents the BAM test program including an innovative test mock-up and most recent test results. Based on these data extrapolation models to extended time periods are discussed, and also future plans to continue tests and to investigate seal behaviour for additional test parameters are explained. Ashford Ramtrans Publ. 2014 Packaging, transport, storage & security of radioactive materials (RAMTRANS) 25 1 8 15 10.1179/1746510914Y.0000000057 2016-02-20 OPUS4-33834 Zeitschriftenartikel Wille, Frank; Wolff, Dietmar; Droste, Bernhard; Völzke, Holger; Baden, M. German approach and feedback on experience of transportability of SNF packages after interim storage In Germany, the concept of dry interim storage of spent fuel in dual purpose metal casks is implemented, currently for periods of up to 40 years. The casks being used have an approved package design in accordance with the international transport regulations. The license for dry storage is granted on the German Atomic Energy Act with respect to the recently revised 'Guidelines for dry interim storage of irradiated fuel assemblies and heat-generating radioactive waste in casks' by the German Waste management Commission. For transport on public routes between or after long term interim storage periods, it has to be ensured that the transport and storage casks fulfil the specifications of the transport approval or other sufficient properties, which satisfy the proofs for the compliance of the safety objectives at that time. In recent years, the validation period of transport approval certificates for manufactured, loaded and stored packages were discussed among authorities and applicants. A case dependent system of 3, 5 and 10 years was established. There are consequences for the safety cases in the Package Design Safety Report, including evaluation of long term behaviour of components and specific operating procedures of the package. The present research and knowledge concerning the long term behaviour of transport and storage cask components have to be consulted as well as experiences from interim cask storage operations. Challenges in the safety assessment are e.g. the behaviour of aged metal and elastomeric gaskets under IAEA test conditions to ensure that the results of drop tests can be transferred to the compliance of the safety objectives at the time of transport after the interim storage period. Assessment methods for the material compatibility, the behaviour of fuel assemblies and the aging behaviour of shielding parts are issues as well. This paper describes the state of the art technology in Germany, explains recent experience on transport preparation after interim storage and points out arising prospective challenges. Ashford Ramtrans Publ. 2014 Packaging, transport, storage & security of radioactive materials (RAMTRANS) 25 2 55 59 10.1179/1746510914Y.0000000064 2016-02-20 OPUS4-38483 Beitrag zu einem Tagungsband Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Ageing and lifetime prediction of O-ring seals made of HNBR, EPDM and FKM BAM is the federal institute for materials research and testing in Germany. One of our tasks is to evaluate the safety of casks designed for transport and/or storage of radioactive waste. As elastomeric seals are used in the containers as safety-relevant parts, it is our goal to be able to evaluate the service lifetime of the seals with regard to the requirements for long-term safety (40 years and more) of the containers. For this reason, an accelerated ageing programme with selected rubbers often used for seals (HNBR, EPDM and FKM) was started. Ageing was performed at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) for up to 2 years. For assessing properties related to the sealability, O-rings were aged in compression by 25 % (corresponding to the compression during service) between plates. For comparison, uncompressed O-rings were aged as well. The aged materials were characterized with conventional polymer analysis methods such as hardness and tensile tests, but also with more seal-specific methods such as compression stress relaxation (CSR, reflecting the loss of sealing force of a compressed seal over time), and compression set (CS, representing the recovery behaviour of a seal after release from compression). CS is chosen as the property for lifetime prediction as it is both sensitive to degradation and related to the seal performance. CS data is extrapolated to 60 °C, which yields lifetimes of approximately 5 years for HNBR and 64 years for EPDM for a criterion of 85 % CS respectively, and approx. 40 years for FKM for a criterion of 65 % CS (the highest value measured so far). Deutsches Institut für Kautschuktechnologie 2016 12. Kautschuk Herbst Kolloquium 2016 9783981407648 12. Kautschuk Herbst Kolloquium Hanover, Germany 22.11.2016 24.11.2016 2016-11-29 OPUS4-38501 Beitrag zu einem Tagungsband Jaunich, Matthias; Grelle, Tobias; Wolff, Dietmar Low temperature properties of elastomer seals - Comparison between purely static and partially released seals - Rubber is widely used as sealing material in various applications. In many fields the function of seal materials at low temperatures is necessary. Therefore the understanding of failure mechanisms that lead to leakage at low temperatures is of high importance. It is known that the material properties of rubbers are strongly temperature dependent. At low temperatures this is caused by the rubber-glass transition (abbr. glass transition). During continuous cooling the material changes from rubber-like entropy-elastic behaviour to stiff energy-elastic behaviour, that allows nearly no strain or retraction, due to the glass transition. Hence rubbers are normally used above their glass transition but the minimum working temperature limit is not defined precisely, what can cause problems during application. Therefore the lower operation temperature limit of rubber seals should be determined in dependence of the material properties. In the past we investigated the material properties and sealing behaviour of elastomeric seals at low temperatures. Additionally we started to study the effect of a small partial release of elastomer seals at low temperatures. To study the influence of dynamic events on seal performance and to enhance the understanding of occurring seal failure, a setup for a fast partial seal release was designed. In this contribution we focus on the correlation of material properties and component behaviour under different application conditions. It is desired to widen the understanding of the process of seal failure at low temperature. Deutsches Institut für Kautschuktechnologie e.V. 2016 12. Kautschuk-Herbst-Kolloquium 9783981407648 12. Kautschuk-Herbst-Kolloquium Hannover, Germany 22.11.2016 24.11.2016 34 2016-12-01 OPUS4-38911 Zeitschriftenartikel Grelle, Tobias; Wolff, Dietmar; Jaunich, Matthias Leakage behaviour of elastomer seals under dynamic unloading conditions at low temperatures In technical applications, static seals are sometimes also subjected to dynamic loadings. Therefore, the leakage behaviour under dynamic conditions has to be evaluated as well. For this purpose, FKM elastomer seals have been tested by using newly designed equipment that allows for rapid partial release of the seal and simultaneous leakage rate measurement at a wide range of test temperatures. Furthermore, material characterisation was done by using Dynamic Mechanical Analysis, Differential Scanning Calorimetry and Compression Set. It was shown that, under static conditions, the leakage rate increased significantly during cooling at temperatures around 18 K lower than the glass transition range. On reheating, the seal's functionality was restored in the high temperature region of the glass rubber transition. In the subsequent dynamic release tests, that comprised a reduction of the seal compression within 1 s from 25 % to 23 %, increased leakage rates were observed in the high temperature region of the glass transition range. It was shown that the temperature that is critical for increased leakage is significantly lower under static conditions compared to dynamic conditions. The obtained leakage rates for static tests and dynamic release tests at different temperatures were analysed with reference to results of the material characterisation. Oxford, UK Elsevier Ltd. 2017 Polymer Testing 58 219 226 10.1016/j.polymertesting.2016.12.018 2017-01-09 OPUS4-44749 Beitrag zu einem Tagungsband Orellana Pérez, Teresa; Völzke, Holger; Wolff, Dietmar; Zencker, Uwe Relevance of cladding failure mechanisms due to zirconium hydride precipitation under extended dry storage conditions in Germany The German nuclear waste management strategy consists of dry interim storage of spent fuel inside dual purpose casks and its subsequent direct final disposal in a deep geological repository. Interim storage is limited to 40 years so far, but will have to be extended until repository site selection and operation is concluded, potentially up to 100 years. In this context, research on the long term performance of safety relevant cask components and fuel rod integrity during such extended periods of time is of outmost importance. The barrier function of the fuel cladding depends on its integrity under operational and accidental conditions along with storage and subsequent transportation and is mainly affected over time by altering of the cladding microstructure and by thermo-mechanical conditions during reactor operation and subsequent wet and dry storage. This paper focuses on failure mechanisms regarding cladding embrittlement caused by physical phenomena concerning hydrogen dissolution and precipitation of hydrides in the zirconium matrix. Within this context, potential cladding integrity issues under extended interim storage conditions followed by transportation are emphasized. Delayed hydride cracking (DHC) is a well-known time-dependent temperature-activated phenomenon failure mechanism of the fuel cladding during reactor operation. The phenomenon consists of hydrogen diffusion and hydride precipitation at the tip of an initial crack and the propagation of the crack to an approximate distance equal to the length of the hydride. This failure mechanism is temperature-activated phenomenon and enhances along with thermal cycling of the fuel cladding, e. g. during reactor shutdowns. DHC shows limited relevance under quasi static storage conditions with continuously lowering temperatures. However, the literature points that DHC may occur when the temperature during storage decreases to a certain level after some decades and in combination with stress concentrations in the cladding material. When spent fuel is transferred to dry storage by vacuum drying, the cladding temperature raises up to peak temperatures of ~370°C. Under these conditions, hydrides dissolute into the zirconium matrix up to the solubility limit defined by the peak temperature and this amount of hydrogen can precipitate in a radial re-oriented fashion due to the temperature decrease during storage. Cladding materials with radially precipitated hydrides show significant embrittlement. Radially oriented hydrides are perpendicularly oriented to hoop stresses representing the most critical configuration. Brittle failure of the cladding then occurs by crack propagation through radially oriented hydrides and finally through the zirconium matrix. The susceptibility to radial hydride precipitation depends on cladding material type and microstructure, hydrogen content, pre-drying hydride distribution, irradiation conditions, and temperature and stress histories during drying and storage operations. This paper addresses major considerations concerning spent fuel cladding embrittlement due to hydride precipitation with regard to the boundary conditions of dry spent fuel storage in Germany. Analytical, numerical, and experimental approaches are to be discussed by BAM in order to identify the specific needs for future R&D work in that area with the purpose to provide the necessary data base for proper safety demonstration and evaluation along with future extended storage licensing procedures. 2017 Proceedings of the 2017 Water Reactor Fuel Performance Meeting 2017 Water Reactor Fuel Performance Meeting Jeju, Korea 10.09.2017 14.09.2017 1 8 2018-04-24 OPUS4-45452 Beitrag zu einem Tagungsband Grelle, Tobias; Wolff, Dietmar; Probst, Ulrich; Jaunich, Matthias; Völzke, Holger Component and material investigations on metal seals for high level radioactive waste containers In Germany casks for interim storage of spent nuclear fuel and high level radioactive waste are equipped with Helicoflex® metal seals as main sealing barrier of the double lid system. The long-term behaviour of those seals is investigated at Bundesanstalt für Materialforschung und -prüfung (BAM) in order to evaluate the safety function of the containment at different temperatures over storage periods of 40 years or more in case extended interim storage becomes necessary. Long-term investigations have been done for ageing times of up to 8.5 years at temperatures ranging from room temperature to 150 °C. It was found that the seal force and useable resilience decrease over time, which is mainly caused by creep deformation of the aluminium (or silver) outer jacket of the seals. This effect becomes stronger with increasing temperature. The ageing processes of the seal material and the overall seal behaviour is under investigation in order to derive analytical descriptions for the long-term seal performance. Thus, standardized tests on the basic seal materials, with focus on aluminium, and additional investigations on the seals as a component are conducted. The current investigations include compression and tension creep measurements as well as tensile testing. Furthermore, ageing of seal segments provides information on the development of the contact area width, jacket thickness and microstructural changes in dependence of time and temperature. The obtained data are used for the development of material models and an analytical approach to describe and predict the time and temperature dependent sealing behaviour in the long-term. 2018 11th International Conference on the Transport, Storage and Disposal of radioactive Materials 11th International Conference on the Transport, Storage and Disposal of Radioactive Materials London, UK 15.05.2018 17.05.2018 18535, 1 6 2018-07-12 OPUS4-44867 Monographie Völzke, Holger; Quercetti, Thomas; Ballheimer, Viktor; Nehrig, Marko; Wolff, Dietmar; Wille, Frank Basic of Transport and Storage of Radioactive Materials Transport and storage of radioactive materials are performed in countries with policy of either closed or open nuclear fuel cycle. The related technologies have been established by accumulation of experiences and researches including demonstrative tests using full scale or scale models and analyses. Those are essential before commercialization, but are often costly and time consuming. Such demonstrative works should not be repeated meaninglessly, but can be shared through this kind of book and used by readers and the future generations to advance the technology effectively. This book systematically provides findings from lots of valuable researches on safety of transport and storage of radioactive materials under normal and accident conditions that have an impact on basis of safe regulations, designs, and operations. Singapore Worlds Scientific Publishing Co Pte Ltd 2018 978-981-3234-03-1 1 376 10.1142/10820 2018-05-09 OPUS4-51293 Zeitschriftenartikel Zaghdoudi, Maha; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Erroneous or Arrhenius: A Degradation Rate-Based Model for EPDM during Homogeneous Ageing To improve the predictive capability of long-term stress relaxation of elastomers during thermo-oxidative ageing, a method to separate reversible and irreversible processes was adopted. The separation is performed through the analysis of compression set after tempering. On the Basis of this separation, a numerical model for long-term stress relaxation during homogeneous ageing is proposed. The model consists of an additive contribution of physical and chemical relaxation. Computer simulations of compression stress relaxation were performed for long ageing times and the results were validated with the Arrhenius treatment, the kinetic study and the time-temperature superposition technique based on experimental data. For chemical relaxation, two decay functions are introduced each with an activation energy and a degradative process. The first process with the lower activation energy dominates at lower ageing times, while the second one with the higher activation energy at longer ageing times. A degradation-rate based model for the evolution of each process and ist contribution to the total system during homogeneous ageing is proposed. The main advantage of the model is the possibility to quickly validate the interpolation at lower temperatures within the range of slower chemical processes without forcing a straight-line extrapolation. 2020 Polymers 12 9 1 21 urn:nbn:de:kobv:b43-512931 10.3390/polym12092152 https://creativecommons.org/licenses/by/4.0/deed.de 2020-09-23 OPUS4-48206 Zeitschriftenartikel Grelle, Tobias; Wolff, Dietmar; Probst, Ulrich; Jaunich, Matthias; Völzke, Holger Component and material investigations on metal seals for high level radioactive waste containers Long-term investigations performed at BAM look to extend the state of knowledge on safety-related components of interim storage containers. Metal seals act as the primary sealing barrier in the bolted double lid closure system of the containers. The behaviour of metal seals has been investigated for ageing times up to 8.5 years and for various temperatures. The main cause for reduction in useable resilience overtime was due to creep deformation of the outer jacket of the seal. London Nuclear Institute 2018 Nuclear future 32 34 2019-06-14 OPUS4-48225 Beitrag zu einem Tagungsband Jaunich, Matthias; Grelle, Tobias; Kömmling, Anja; Wolff, Dietmar; Völzke, Holger Stuke, M. Long-term evaluation of sealing systems for radioactive waste packages The investigation of the long-term performance of sealing systems employed in containers for radioactive waste and spent nuclear fuel is one research focus area for division 3.4 "Safety of Storage Containers" at the Bundesanstalt für Materialforschung und -prüfung (BAM). Our investigations comprise investigations on metallic and elastomeric seals and covers experimental investigations to get a database on the component/material behaviour, work on analytical descriptions and numerical analysis. Our aim is to understand the long-term behaviour of the sealing systems for evaluation of their performance during possible extended interim storage and subsequent transportation. GRS 2019 Proceedings of the 3rd Workshop on Safety of Extended Dry Storage of Spent Nuclear Fuel 3rd Workshop on Safety of Extended Dry Storage of Spent Nuclear Fuel Garching, Germany 05.06.2019 07.06.2019 57 62 2019-06-20 OPUS4-51060 Zeitschriftenartikel Kömmling, Anja; Jaunich, Matthias; Goral, Milan; Wolff, Dietmar Insights for lifetime predictions of O-ring seals from five-year long-term aging tests O-rings made of HNBR, EPDM and FKM were aged in the compressed and uncompressed state at 150 °C, 125 °C, 100 °C, 75 °C, 60 °C and 23 °C for aging times of up to five years. Hardness was measured and increased with aging time and temperature for HNBR and EPDM, but it remained practically constant for FKM. Indenter modulus measurements were performed on the lateral O-ring surface (that was free of DLO effects) to assess an influence of the compression during aging, but none was detected. The equilibrium compression set (CS) exhibited faster and stronger degradation than hardness and was used for lifetime predictions using the time-temperature superposition (TTS) principle. With an end-of-lifetime criterion of 70 % CS, lifetimes of 4.5 years, 50 years and 526 years at 75 °C were estimated for HNBR, EPDM and FKM, respectively. The activation energies derived from an Arrhenius plot of the shift factors from the TTS were 85 kJ/mol, 99 kJ/mol and 78 kJ/mol for HNBR, EPDM and FKM, respectively, revealing that a higher activation energy does not necessarily mean that the material has a higher lifetime at lower temperatures. Furthermore, the measured lifetime of EPDM O-rings at 100 °C (5 years) was compared to that predicted on the basis of the lifetime at 150 °C as well as 125 °C using the corresponding shift factors. The error of the prediction was only ± 4 %. However, this precise prediction could only be achieved using the five-year long-term aging data. When using only data from aging times up to 0.5 years and 2 years, the lifetime of EPDM O-rings at 100 °C was underestimated by 31 % and 22 %, respectively. Elsevier Ltd. 2020 Polymer Degradation and Stability 179 109278 10.1016/j.polymdegradstab.2020.109278 2020-07-29 OPUS4-51161 Zeitschriftenartikel Zaghdoudi, Maha; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Overview of ongoing long-term ageing investigations on elastomer seals At the Bundesanstalt für Materialforschung und -prüfung (BAM) in Division 3.4 Safety of Storage Containers, one of our tasks is to evaluate the safety of containers designed for disposal of low and intermediate radioactive waste. As such containers might be transported before and stored until disposal, safe enclosure of the radioactive inventory is important for this time span. Elastomer O-rings are widely used as barrier seals in these containers. Thus, as for many other applications, an understanding of the practical effects of ageing degradation on elastomer seals during long-term exposure is mandatory for predicting the lifetime of such components. According to a long-term test programme on three kinds of rubbers (EPDM and FKM (relevant for application), HNBR (for comparison)), over several years we have studied the degradation and the change of mechanical properties (e.g. hardness, strain at break) at four different ageing temperatures (75 °C, 100 °C, 125 °C and 150 °C) as well as the change of sealing properties. Continuous and intermittent compression stress relaxation (CSR) measurements were performed in order to investigate the respective contribution of crosslinking and chain scission to the observed degradation effects. Thus, the degradation kinetics and mechanisms could be resolved more clearly. For assessing the seal performance, compression set (CS) and leakage rate measurements were conducted. The experimental results showed that the O-rings remained leak-tight under purely static conditions even when CSR, CS and mechanical properties already indicated far advanced degradation. For this reason, a modified leakage test involving a small and rapid partial decompression of the seal was developed that enabled determining an end-of-lifetime criterion for O-rings with a safety margin for thermal shrinkage and vibrations. Ratingen Gupta 2020 Rubber, fibres, plastics international - RFP 15 3 146 151 2020-09-07 OPUS4-51207 Zeitschriftenartikel Zaghdoudi, Maha; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Übersicht über laufende Untersuchungen zur Langzeitalterung von Elastomerdichtungen Eine Aufgabe des Fachbereichs 3.4 Sicherheit von Lagerbehältern der Bundesanstalt für Materialforschung und -prüfung (BAM) ist es, die Sicherheit von Behältern zur Lagerung von radioaktivem Abfall mit vernachlässigbarer Wärmeentwicklung zu bewerten. Da solche Behälter vor der Entsorgung transportiert und gelagert werden, ist während dieser Zeit ein sicherer Einschluss des radioaktiven Inhalts von größter Bedeutung. Zur Abdichtung dieser Behälter sind Elastomer-O-Ringe weit verbreitet. Um für solche, wie auch für viele andere Anwendungen, eine Voraussage über die Lebensdauer dieser Komponenten treffen zu können, ist es unerlässlich zu verstehen, welchen Einfluss der durch Alterung hervorgerufene Abbau auf Dauer auf die Elastomerdichtungen hat. In einem Langzeittest wurden drei Kautschukarten (EPDM und FKM, die für die Anwendung relevant sind, und HNBR als Vergleich) über mehrere Jahre untersucht. Dabei wurden die Veränderungen der mechanischen Eigenschaften (z. B. Härte und Bruchdehnung) bei vier verschiedenen Alterungstemperaturen (75 °C, 100 °C, 125 °C und 150 °C) sowie das Dichtungsverhalten betrachtet. Um den Einfluss von Vernetzung und Kettenspaltung auf die beobachteten Alterungseffekte zu bestimmen, wurden Messungen zur kontinuierlichen und intermittierenden Druckspannungsrelaxation durchgeführt. Dadurch konnten Erkenntnisse über Kinetik und Mechanismus der Abbaureaktionen gewonnen werden. Zur Einschätzung des Dichtungsverhaltens wurden Durckverformungsrest und Leckagerate gemessen. Die Ergebnisse zeigen, dass die O-Ringe unter statischen Bedingungen auch dann dicht halten, wenn die Werte für Druckverformungsrest, Druckspannungsrelaxation und mechanische Eigenschaften schon auf einen fortgeschrittenen Alterungsabbau hindeuten. Aus diesem Grund wurde ein modifizierter Dichtigkeitsversuch mit einer geringen und schnellen teilweisen Entlastung der Dichtung entwickelt, mit dessen Hilfe sich ein Lebensdauerkriterium bestimmen lässt, das eine Sicherheitsspanne für thermische Schrumpfung und Vibrationen beinhaltet. Ratingen Gupta 2020 Gummi, Fasern, Kunststoffe - GAK 73 07-08 326 332 2020-09-14 OPUS4-35775 Zeitschriftenartikel Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Effects of heterogeneous aging in compressed HNBR and EPDM O-ring seals Seals used in containers for dangerous goods need to maintain leak tightness for several decades. For investigating the change in seal material properties during aging, a comprehensive aging program on both uncompressed and compressed EPDM and HNBR seals was started. In order to obtain results closely related to practical conditions, O-rings with a full-scale cord diameter of 10 mm were aged. However, this set-up can lead to heterogeneous aging caused by diffusion-limited oxidation (DLO) effects. These effects depend on material, dimensions, time and temperature. Heterogeneous aging results in distorted bulk properties such as compression stress relaxation and compression set (CS) suggesting that HNBR has better performance than EPDM at 150 °C but which is not the case at 100 °C. The presence of heterogeneous material properties was shown by hardness measurements across the seal cross-section. If DLO-affected data is excluded, extrapolations of CS data are possible using time-temperature shifts and Arrhenius graphs. Exemplary CS values of 50 % and 80 % would be reached after approx. 10 years and 29 years, respectively for HNBR and after approx. 400 years and 1100 years, respectively for EPDM. Oxford Elsevier Science 2016 Polymer Degradation and Stability 126 39 46 10.1016/j.polymdegradstab.2016.01.012 2016-04-20 OPUS4-33552 Zeitschriftenartikel Jaunich, Matthias; Wolff, Dietmar Influence of gamma irradiation on low temperature properties of rubber seal materials In many fields the function of seal materials is required at low temperatures. Therefore the understanding of failure mechanisms at low temperatures is of high importance. In some applications elastomeric seals are used in environments with increased irradiation backgrounds, as e.g. in containers for radioactive waste. This paper reports on the influence of gamma irradiation on the low temperature properties of different fluorocarbon rubber (FKM) materials. The samples were irradiated with gamma doses of up to 600 kGy and the induced changes of material properties were tested by methods sensitive to the rubber-glass transition, like DSC and DMA. Additionally, compression set measurements were performed to give information about recovery behaviour at low temperatures. Heidelberg Hüthig Deutsche Kautschuk-Gesellschaft 2015 Kautschuk, Gummi, Kunststoffe (KGK) 68 6 85 89 2016-02-20 OPUS4-33553 Beitrag zu einem Tagungsband Jaunich, Matthias; Weber, Mike; Kömmling, Anja; Zencker, Uwe; Wolff, Dietmar; Völzke, Holger Performance of elastomer seals in transport and storage casks Elastomer seals are widely used as barrier seals in containers for low and intermediate level radioactive waste and for spent fuel transportation casks. In addition, they are also used for spent fuel storage and transportation casks (dual purpose casks (DPC)) as auxiliary seals to allow leakage rate measurements of metal barrier seals for demonstration of their proper assembling conditions. Depending on the area of use, the rubber materials have to demonstrate proper sealing performance with regard to mechanical, thermal, and environmental conditions as well as irradiation during the entire operation period. Concerning DPC, degradation effects should be limited in a way that, for example, effects from potentially released decomposition elements may not harm e.g. metal barrier seals. Leakage rate measurements should be possible also after long interim storage periods prior to subsequent transportation. Because of the complex requirements resulting from the various applications of containers for radioactive waste and spent nuclear fuel, BAM has initiated several test programmes for investigating the behaviour of elastomer seals. In this contribution the current status is described and first results are discussed. International Atomic Energy Agency (IAEA) 2015 International conference on management of spent fuel from nuclear power reactors: An integrated approach to the back end of the fuel cycle International conference on management of spent fuel from nuclear power reactors: An integrated approach to the back end of the fuel cycle Vienna, Austria 15.06.2015 19.06.2015 1 8 2016-02-20 OPUS4-33489 Beitrag zu einem Tagungsband Jaunich, Matthias; Grelle, Tobias; Wolff, Dietmar Investigation of elastomer seal behaviour for transport and storage packages According to the relevant guidelines and regulations, the safe enclosure of radioactive Container contents has to be guaranteed for long storage periods as well as down to temperatures of -40 °C during transportation. As rubbers are widely used as the main sealing materials for Containers for low- and intermediate-level radioactive waste and as additional component to metal seals in spent fuel and high active waste Containers, a comprehensive eiastomer investigation Programme is in place at BAM. This Programme comprises investigations of overall eiastomer performance, durability, influence of gamma irradiation and low temperature behaviour. In this paper we focus on the behaviour of eiastomer seals at low temperatures with regard to the potential increase in leakage as material properties of rubbers are strongly temperature-dependent. During continuous cooling, the material behaviour of elastomers changes in the rubber-glass transition temperature ränge from rubberlike entropy-elasticity to stiff energy-elasticity, allowing for almost no strain or retraction. Hence rubbers are normally used above their rubber-glass transition but the minimum limit at which they work has not been defined precisely. For the investigations, fluorocarbon (FKM) and ethylene-propylene-diene (EPDM) rubbers were selected, as they are often used in radioactive waste Containers. The elastomers were studied using several thermoanalytical methods and compression set. The results were compared with component tests to determine the temperature at which the sealing function of O-rings made of eiastomer breaks down. In addition to these results, under static conditions we designed a new measurement set-up which allows for a small deflection of the flange and simultaneous leakage rate measurement at low temperatures. 2015 RAMTRANS 2015 - 10th International conference on radioactive materials transport and storage (Proceedings) RAMTRANS 2015 - 10th International conference on radioactive materials transport and storage Oxford, UK 19.05.2015 21.05.2015 1 10 2016-02-20 OPUS4-35050 Beitrag zu einem Tagungsband Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Alterung von Elastomerdichtungen für Lagerbehälter Unsere Aufgabe im Fachbereich 3.4 der Bundesanstalt für Materialforschung und prüfung (BAM) ist die sicherheitstechnische Begutachtung von Transport- und Lagerbehältern für radioaktiven Abfall, die für langfristige Zwischenlagerung ausgelegt sind. Ein Arbeitsschwerpunkt ist die Bewertung der Lebensdauer von Metall- und Elastomerdichtungen in den Behältern im Hinblick auf die Anforderungen für langfristige Behältersicherheit (min. 40 Jahre in Deutschland). Um die Eigenschaftsänderungen der Elastomerdichtungen während einer beschleunigten Alterung über lange Zeiträume (bis zu fünf Jahre) untersuchen zu können, wurde ein Alterungsprogramm an ausgewählten Elastomeren (HNBR, EPDM, FKM) begonnen. Im Gegensatz zu Normalterungsverfahren altern wir keine Normteile, sondern O-Ringe im unverpressten sowie verpressten Zustand. Diese Vorgehensweise ermöglicht die Bewertung des Einflusses der Verpressung auf die Alterung sowie die Untersuchung des Bauteilversagens mittels Leckageratenmessungen unter anwendungsnahen Bedingungen. Weitere Charakterisierungsmethoden sind Härtemessung, dynamisch-mechanische Analyse (DMA), Thermogravimetrie (TGA), Druckspannungsrelaxation, Druckverformungsrest (DVR), Dichtebestimmung und Zugversuch. Das Ziel ist, die Leckagerate mit anderen Eigenschaften bzw. Methoden zu korrelieren, um so ein aussagekräftiges und leichter zu bestimmendes Lebensdauerkriterium für elastomere O-Ringe abzuleiten. Während der Alterung können in Abhängigkeit von Material sowie Alterungsdauer und -temperatur Inhomogenitäten aufgrund von diffusionsbegrenzter Oxidation auftreten, durch die sich unterschiedliche Eigenschaften an der Oberfläche und im Volumen der Dichtung ergeben, was zu falschen Lebensdauerabschätzungen führen kann. Mittels Mikrohärtemessung über den Querschnitt werden diese Effekte charakterisiert und bei der Extrapolation mittels Zeit-Temperatur-Verschiebung und Arrheniusgraph berücksichtigt. Bisher liegen Daten von bis zu einem Jahr bei vier verschiedenen Temperaturen (75 °C, 100 °C, 125 °C und 150 °C) gealterten Proben vor. Nach 100 Tagen bei 150 °C weisen HNBR und EPDM schon einen DVR von über 80 % auf, aber noch keinen signifikanten Anstieg der Leckagerate. Diese sinkt zunächst während der Alterung, da die Permeabilität aufgrund von Vernetzungsreaktionen sinkt. Bei HNBR ist dies aufgrund der dominanteren Vernetzungsreaktionen während der Alterung noch stärker ausgeprägt als bei EPDM. Chemnitz Technische Universität Chemnitz 2015 Technomer 2015 - 24. Fachtagung über Verarbeitung und Anwendung von Polymeren 978-3-939382-12-6 Technomer 2015 - 24. Fachtagung über Verarbeitung und Anwendung von Polymeren Chemnitz, Germany 12.11.2015 13.11.2015 43 2016-02-20 OPUS4-35155 Vortrag Wolff, Dietmar Transport- und Lagerbehälter für trockene Zwischenlagerung bestrahlter Brennelemente und Wärme entwickelnder radioaktiver Abfälle - Teil 1 2015 KKW Brunsbüttel - Veranstaltungsreihe zum Erhalt der Fachkunde des Personals KKW Brunsbüttel - Veranstaltungsreihe zum Erhalt der Fachkunde des Personals Brunsbüttel 2015-10-27 2016-02-20 OPUS4-35157 Vortrag Wolff, Dietmar Transport- und Lagerbehälter für die trockene Zwischenlagerung bestrahlter Brennelemente und Wärme entwickelnder radioaktiver Abfälle - Teil 2 2015 KKW Brunsbüttel - Veranstaltungsreihe zum Erhalt der Fachkunde des Personals KKW Brunsbüttel - Veranstaltungsreihe zum Erhalt der Fachkunde des Personals Brunsbüttel 2015-11-10 2016-02-20 OPUS4-35158 Vortrag Wolff, Dietmar Metal and elastomer seal investigation 2015 2015 Used Fuel - High Level Waste Meeting of the Extended Storage Collaboration Program (ESCP) 2015 Used Fuel - High Level Waste Meeting of the Extended Storage Collaboration Program (ESCP) Charlotte, NC, USA 2015-12-01 2015-12-03 2016-02-20 OPUS4-35130 Beitrag zu einem Tagungsband Jaunich, Matthias; Grelle, Tobias; Wolff, Dietmar Influence of partial release on sealing performance of elastomer O-rings at low temperatures For many sealing applications rubbers are applied due to their special material properties and easy use. In many applications as e.g. in aviation, traffic or process technology the material can be exposed to low temperatures during operation. Therefore it is important to know the material behaviour at those low temperatures to determine the temperature range that allows a safe operation of the seal. As rubbers are used as main sealing materials for containers for low and intermediate level radioactive waste and as additional component to metal seals in spent fuel and high acitve waste containers, a comprehensive elastomer investigation program is run at BAM. This program comprises investigations of elastomer overall performance, durability, influence of gamma irradiation and low temperature behaviour. In this paper we focus on the behaviour of elastomer seals below ambient temperatures after a fast partial release. Despite the primarily static application conditions of many seals their behaviour after partial compression release is of interest with regard to potential decrease of leak-tightness. For this investigation a special setup was designed which allows the partial release of compressed seal systems at different temperatures accompanied by leakage rate measurements. The results for FKM seals are presented and discussed. Chemnitz Technische Universität Chemnitz 2015 Technomer 2015 - 24. Fachtagung über Verarbeitung und Anwendung von Polymeren 978-3-939382-12-6 Technomer 2015 - 24. Fachtagung über Verarbeitung und Anwendung von Polymeren Chemnitz, Germany 12.11.2015 13.11.2015 P 3.7, 1 6 2016-02-20 OPUS4-33782 Beitrag zu einem Tagungsband Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Ageing of elastomeric seals for storage containers At BAM Federal Institute for Materials Research and Testing in Germany, it is our responsibility to audit the safety of casks designed for transport and/or storage of radioactive material. With regard to the requirements on long-term safety of the containers, it is necessary to evaluate the service lifetime of the elastomeric seals used in the containers. With ageing, the elastomers will gradually lose their elasticity and their ability for recovery, which might result in a leakage above the allowed level or in a release of radioactivity during an incident. It is important to know the rate of degradation and which property can be used as an practical and easily measurable end-of-lifetime criterion. For this reason, we devised ageing experiments on different kinds of elastomers, namely FKM, EPDM and HNBR. The former two are actually used in containers for radioactive wastes - either as auxiliary seal in casks containing high activity waste, or as main seal in casks for medium or low activity waste. The latter is an often used seal material that is tested for comparative reasons. In our ageing program, these three materials are aged at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) in order to extrapolate the data to service temperature using a suitable model. They are examined at logarithmic time intervals of several days up to 5 years. The samples are aged in their undeformed O-ring state as well as compressed between flanges with a deformation corresponding to the actual compression during service. Thus we can compare the ageing between relaxed and stressed sample. Additionally, we are ageing samples in flanges that allow leakage rate measurements. Other measurements include monitoring of the recovery force of the seal and the compression set. Furthermore, the samples are examined by thermal and dynamic-mechanical analysis for detecting changes in the glass transition temperature due to crosslinking or chain scission in the material. Besides, hardness is measured as a practical macroscopic indicator. Until now, we have analyzed samples aged up to 100 days. At the highest ageing temperature of 150 °C, the compressed EPDM has already reached a compression set of 95 %, while HNBR and FKM have reached 80 % and 30 %, respectively. Furthermore, HNBR has reached a Shore D hardness of 85, which is an immense increase after the initial value of 80 Shore A. However, when looking at the cross-section of the sample, it was obvious that only a layer of about 1 mm thickness has become so hard, while the inner part remained rubbery. This shows that there has been intense crosslinking mostly near the surface of the HNBR which forms a kind of oxygen diffusion barrier, inhibiting the thermooxidation of the inner part of sample which can retain elastic properties. In EPDM, the oxygen permeability is much greater, which leads to a more homogeneous degradation across the whole sample and thus resulted in a higher compression set. The low compression set of FKM shows the outstanding high-temperature properties of this material. INFORUM-Verl. u. Verwaltungsges. Kerntechnische Gesellschaft e.V. (KTG) 2015 Annual Meeting on Nuclear Technology 2015 978-3-926956-98-9 Annual Meeting on Nuclear Technology 2015 Berlin, Germany 2015-05-05 2015-05-07 1 10(?) 2016-02-20 OPUS4-33784 Beitrag zu einem Tagungsband Jaunich, Matthias; Grelle, T.; Wolff, Dietmar Influences on the low temperature sealability of elastomer O-rings For many sealing applications rubbers are applied due to their special material properties and easy use. In many applications, e.g. in aviation, traffic or process technology the material can be exposed to low temperatures during Operation. Therefore it is important to know the material behaviour at those low temperatures to determine the temperature range that allows a safe Operation of the seal. As rubbers are used as main sealing materials for Containers for low and intermediate level radioactive waste and as additional component to metal seals in spent fuel and high active waste Containers, a comprehensive elastomer investigation program is run at BAM. This program comprises investigations of elastomer overall performance, durability, influence of gamma irradiation and low temperature behaviour. In this paper we focus on the behaviour of elastomer seals at low temperatures with regard to potential decrease of leak-tightness as material properties of rubbers are strongly temperature dependent. But additionally to the investigation presented in the past which considered the material properties of new materials and the seal behaviour under purely static conditions [1, 2] we now focus on irradiated materials and on the sealing performance after a fast partial release of the compressed seal. For the investigations different materials were used, e.g. fluorocarbon (FKM) and ethylenepropylene-diene (EPDM) rubber. To determine the effect of gamma irradiation some samples were irradiated and studied by several thermo-analytical methods and compression set. For the investigation of the seal performance under non static conditions we decided to design a new measurement setup which allows for a small flange deflection and simultaneous leakage rate measurement at low temperatures. Deutsche Kautschuk-Gesellschaft e.V. 2015 IRC 2015 - International rubber conference / DKT 2015 - Deutsche Kautschuk-Tagung IRC 2015 - International rubber conference Nuremberg, Germany 29.06.2015 02.07.2015 1 7 2016-02-20 OPUS4-34445 Zeitschriftenartikel Grelle, Tobias; Wolff, Dietmar; Jaunich, Matthias Temperature-dependent leak tightness of elastomer seals after partial and rapid release of compression A device has been designed, built and tested that allows the investigation of effects of dynamic loads on the leak tightness of elastomer seals at low temperatures. With the test setup, the compression of the tested seal can be reduced by a defined degree in a time period of less than 1 s. For the evaluation of the leak tightness, leakage rates can be determined. It was shown that the rapid partial release of an elastomer seal leads to its failure already at the beginning of the rubber-glass transition and, therefore, at significantly higher temperatures than the loss of leak tightness observed under static conditions. Amsterdam [u.a.] Elsevier Ltd. 2015 Polymer Testing 48 44 49 10.1016/j.polymertesting.2015.09.009 2016-02-20 OPUS4-34939 Beitrag zu einem Tagungsband Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Ageing of elastomeric seals for storage containers At BAM Federal Institute for Materials Research and Testing in Germany, it is our responsibility to evaluate the safety of casks designed for transport and/or storage of radioactive material. This includes the investigation of elastomeric seals applied in the containers. Besides examining the low-temperature behavior of elastomeric seals, it is our goal to evaluate the service lifetime of the seals with regard to the requirements for long-term safety (40 years and more) of the containers. Furthermore, we deem it necessary to exceed the requirements given in the ageing standard DIN 53508 and take into account diffusion-limited oxidation (DLO) effects and non-Arrhenius behavior when making lifetime predictions. Therefore, we started an ageing programme with selected rubbers (HNBR, FKM and EPDM) which are oven-aged at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) in order to extrapolate the data to service temperature using different models and check which one is appropriate. Samples are examined at different times up to 5 years. In order to be able to compare between compressed and relaxed rubber, they are aged in two conditions: the undeformed O-ring state as well as compressed between plates with a compression of 25 % corresponding to the actual compression during service. Additionally, we are ageing samples in flanges that allow leakage rate measurements which is the central performance criterion. Analysis methods include hardness as a quick indicator, compression set and compression stress relaxation as measures reflecting the actual properties of a compressed seal. Additionally, we are applying classical polymer analysis methods like dynamic mechanic analysis and thermogravimetric analysis which show changes in the polymeric structure due to chain scission and crosslinking. Furthermore, we are testing the leakage rate of the O-rings in order to correlate the changes in physical properties to the actual performance of the seal. First results of samples aged up to 100 days show a strong increase in hardness for HNBR, a moderate increase for EPDM and hardly a change for FKM. A similar result is seen in the compression set of samples aged 100 d at 100 °C in compression as HNBR has reached 60 %, EPDM 25 % and FKM 15 % compression set. However, after ageing at 150 °C, EPDM shows a worse performance with 95 % compression set compared to HNBR with only 80 %. This is probably due to DLO effects in HNBR that appear because of the fast ageing and low oxygen permeability in HNBR. This leads to a deficit of oxygen in the center of the sample which is thus protected from ageing and can retain elastic properties. The full paper shall discuss the changes in material properties observed to date and the impact on the performance of elastomeric seals. Deutsche Kautschuk-Gesellschaft e.V. 2015 IRC 2015 - International rubber conference / DKT 2015 - Deutsche Kautschuk-Tagung IRC 2015 - International rubber conference Nürnberg, Germany 29.06.2015 02.07.2015 1 10 2016-02-20 OPUS4-30820 Beitrag zu einem Tagungsband Jaunich, Matthias; Wolff, Dietmar Van Breugel, K.; Koenders, E.A.B. Approach for the investigation of long-term behaviour of elastomeric seals for transport and storage packages Elastomers are widely used as main sealing materials for Containers for low and intermediate Ievel radioactive waste and as additional component to metal seals in spent fuel and high active waste Containers. According to appropriate guidelines and regulations safe enclosure of the radioactive Container contents has to be guaranteed for long storage periods as well as down to temperatures of -40 °C for transportation. Therefore the understanding of seal behaviour in general is of high importance and ageing of elastomeric seals has to be considered with regard to possible dynamic events taking possibly place during transport after storage. TU Delft 2014 AMS 14 - Ageing of materials & structures - Proceedings of the 1st ageing of materials & structures 2014 conference 978-94-6186-313-3 1st Ageing of materials & structures 2014 conference Delft, The Netherlands 26.05.2014 28.05.2014 87 93 2016-02-20 OPUS4-30821 Beitrag zu einem Tagungsband Nagelschmidt, Sven; Herbrich, Uwe; Probst, Ulrich; Wolff, Dietmar Van Breugel, K.; Koenders, E.A.B. Evaluation of test results with regard to ageing mechanisms of metal seals in casks for dry storage of spent nuclear fuel Metal seals are widely used for extreme applications, e.g. in dual-purpose casks for dry interim storage of spent nuclear fuel in Germany. Due to the fact that interim storage must be safe at least for the approved period of 40 years there is a major interest to investigate the long-term behaviour and ageing mechanisms of metal seals. Experimental analyses indicate a time and temperature dependency of seal characteristics. This dependency was researched with a time- and temperature parameterization based up on Larson-Miller. The paper describes the derivation of the material parameter C from test results and the applicability of the Larson-Miller-Relationship for those metal seals in principle. Overall a constant material parameter C was not. Nevertheless, an approach comparable to the Larson-Miller-Parameter was developed. TU Delft 2014 AMS 14 - Ageing of materials & structures - Proceedings of the 1st ageing of materials & structures 2014 conference 978-94-6186-313-3 1st Ageing of materials & structures 2014 conference Delft, The Netherlands 26.05.2014 28.05.2014 126 133 2016-02-20 OPUS4-49019 Beitrag zu einem Tagungsband Grelle, Tobias; Probst, Ulrich; Wolff, Dietmar; Jaunich, Matthias; Völzke, Holger Investigations on the long-term behavior of metal seals for dual purpose casks In Germany, spent nuclear fuel and high active waste from reprocessing is stored in transport and storage containers with double lid systems that are equipped with metal seals completing the primary sealing barrier. The tasks of the Bundesanstalt für Materialforschung und -prüfung (BAM) within the interim storage licensing procedures ruled by the German Atomic Energy Act include the long-term safety evaluation of the container design regarding the permanently safe enclosure of the inventory. In order to generate a knowledge base for the safety evaluation, research regarding the long-term behavior of the critical components is performed. So far, the containers are licensed for an interim storage period of 40 years. However, due to significant delays in establishing a final repository, the required time span for interim storage is expected to increase significantly. Thus, a widespread investigation program is run to gain systematic data on the long-term behavior of the seals and to develop prediction models. Long-term seal investigations consider the development of their restoring seal force, their useable resilience and their achievable leakage rate caused by aging at temperatures ranging from room temperature up to 150 °C. This year, the total time span of the tests reaches 10 years. Furthermore, seal segments are aged at the selected temperatures for up to 300 days. From these segments additional information on the sealing behavior, changes of the seal contact and the material behavior is gained. This contribution deals with the current results of the long-term seal investigations at BAM. Furthermore, insights of the more in-depth component and material investigations of the metal seals with focus on the seal contact development are discussed and the ongoing work aiming for an analytical description of the thermo-mechanical aging effects on metal seals are presented. 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 1 6 2019-09-20 OPUS4-48519 Buchkapitel Wolff, Dietmar; Völzke, Holger; Bevilacqua, A.; Alejano, C.; Conde, J.M.; Einziger, R.E.; Fukuda, S.-I.; González Espartero, A.; Gouzy-Portaix, S.; Haddad Andalaf, R.E.; Hambley, D.; Issard, H.; Kessler, J.; Kurpaska, L.; Legat, A.; Qureshi, A.H.; Ruiz, J.; Shirai, K.; Šmaižys, A.; Verrastro, C.A. González Espartero, A. Demonstrating performance of spent fuel and related storage system components during very long term storage - Final report of a coordinated research project This publication summarizes the work carried out during an IAEA coordinated research project (CRP) on safe and reliabe management of spent nuclear fuel. This work contributes to the overall goal of demonstrating the performance of spent nuclear fuel and related storage systems components over long durations, and facilitates the transfer of this knowledge to Member States. The technical areas addressed by the CRP participants were related to potential degradation mechanisms in metal casks and concrete overpacks, such as stress corrosion cracking; long term integrity and performance of the fuel cladding; thermo-mechanical behaviour of the metal seals; and long term gamma and neutron shielding capability. The participants also considered past and ongoing demonstration programmes. For each technical topic addressed the main conclusions have been drawn, including information on the development of specific monitoring and inspection techniques as well as future opportunities for closing relevant data gaps. A major achievement is also the establishment of a worldwide network of experts working on current research projects to demonstrate the long term performance of spent fuel in dry storage systems. Vienna, Austria IAEA Publishing Section International Atomic Energy Agency 2019 IAEA TecDoc Series 1878 978–92–0–103319–2 1 198 2019-07-22 OPUS4-48609 Zeitschriftenartikel Zaghdoudi, Maha; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Scission, cross-linking, and physical relaxation during thermal degradation of elastomers Elastomers are susceptible to chemical ageing, i.e., scission and cross-linking, at high temperatures. This thermally driven ageing process affects their mechanical properties and leads to limited operating time. Continuous and intermittent stress Relaxation measurements were conducted on ethylene propylene diene rubber (EPDM) and hydrogenated nitrile butadiene rubber (HNBR) samples for different ageing times and an ageing temperature of 125 °C. The contributions of chain scission and cross-linking were analysed for both materials at different ageing states, elucidating the respective ageing mechanisms. Furthermore, compression set experiments were performed under various test conditions. Adopting the two-network model, compression set values were calculated and compared to the measured data. The additional effect of physical processes to scission and cross-linking during a long-term thermal exposure is quantified through the compression set analysis. The characteristic times relative to the degradation processes are also determined. MDPI 2019 Polymers 11 8 1280, 1 12 urn:nbn:de:kobv:b43-486091 10.3390/polym11081280 https://creativecommons.org/licenses/by/4.0/deed.de 2019-08-02 OPUS4-48612 Zeitschriftenartikel Kömmling, Anja; Jaunich, Matthias; Pourmand, P.; Wolff, Dietmar; Hedenqvist, M. Analysis of O-ring seal failure under static conditions and determination of end-of-lifetime criterion Determining a suitable and reliable end-of-lifetime criterion for O-ring seals is an important issue for long-term seal applications. Therefore, seal failure of ethylene propylene diene rubber (EPDM) and hydrogenated nitrile butadiene rubber (HNBR) O-rings aged in the compressed state at 125 °C and at 150 °C for up to 1.5 years was analyzed and investigated under static conditions, using both non-lubricated and lubricated seals. Changes of the material properties were analyzed with dynamic-mechanical analysis and permeability experiments. Indenter modulus measurements were used to investigate DLO effects. It became clear that O-rings can remain leak-tight under static conditions even when material properties have already degraded considerably, especially when adhesion effects are encountered. As a feasible and reliable end-of-lifetime criterion for O-ring seals under static conditions should include a safety margin for slight dimensional changes, a modified leakage test involving a small and rapid partial decompression of the seal was introduced that enabled determining a more realistic but still conservative end-of-lifetime criterion for an EPDM seal. Basel, CH MDPI 2019 Polymers 11 8 1251, 1 19 urn:nbn:de:kobv:b43-486125 10.3390/polym11081251 https://creativecommons.org/licenses/by/4.0/deed.de 2019-08-02 OPUS4-48514 Vortrag Wolff, Dietmar Ageing management issues for extended SF and HLW dry storage in Germany - Challenges, approach, examples In this presentation, the history and actual situation of the German nuclear waste management policy of spent fuel (SF) and high-level waste (HLW) is reported. Beside the description of the restructuration of responsible authorities and organizations in Germany, the principle of dry interim storage of SF and HLW in dual purpose casks is explained. The need for extended interim storage towards disposal implicates additional challenges for the nuclear waste management strategy in Germany. (Extended)interim storage, subsequent transportation, and final disposal are closely linked. Integrated approaches concerning waste package designs and operations are supposed to be beneficial for the establishment of efficient long-term SF and HLW management strategies. Knowledge management and staff recruiting, education and training during phase out and beyond nuclear power plant operation are major issues. 2019 IAEA - Second Coordinate Research Meeting and Consultancy Meeting on Ageing Management Programmes for Spent Fuel Dry Storage Systems Lemont, IL, USA 29.04.2019 03.05.2019 2019-07-22 OPUS4-51833 Zeitschriftenartikel Jaunich, Matthias; Goral, Milan; Wolff, Dietmar; Völzke, Holger Krüssenberg, A. Overview of metal seal tests performed at BAM and implications for extended interim storage The investigation of the long-term performance of sealing systems employed in containers of radioactive waste and spent nuclear fuel is one research focus area for division 3.4 \Safety of Storage Containers" at the Bundesanstalt für Materialforschung und -prüfung. The behaviour of metallic seals, which are employed in interim storage casks for spent nuclear fuel and high active waste, over time is of high importance for ensuring safe enclosure. Therefore, investigations on these systems were started at BAM to get a general understanding of the relevant processes. Our investigations comprise investigations on different parameters which influence the seal Performance and the main part is focussed on the time and temperature dependent behaviour. Our aim is to understand the longterm behaviour of the sealing systems for evaluation of their performance during possible extended interim storage and subsequent transportation. In this contribution an overview of the performed tests and their respective results is given. A focus lies on a comparison between seals with large torus diameter in comparison to small diameters. München Carl Hanser Verlag 2020 Kerntechnik 85 Safety of Extended Dry Storage of Spent Nuclear Fuel SEDS2020: International online-workshop Online meeting 03.06.2020 6 440 443 10.3139/124.200071 2020-12-16 OPUS4-51486 Beitrag zu einem Tagungsband Kömmling, Anja; Simbruner, Kai; Grelle, Tobias; Jaunich, Matthias; Zencker, Uwe; Wolff, Dietmar; Orellana Pérez, Teresa; Völzke, Holger Research at BAM for evaluating long term safety of container systems and components Safety of long term containment and storage of radioactive waste is an essential issue, which is increasingly gaining international attention. Extending interim storage beyond initial license periods is one of the major challenges worldwide. BAM has been involved in all kinds of radioactive waste container safety evaluation for storage and transportation including their long term performance from the very beginning. Today, all work related to the safe management of radioactive waste is linked by the activity field "Nuclear Waste Management" within the Focus Area "Energy" at BAM and in conjunction with a research strategy and agenda. Most recently, the working group "Long Term Safety of Container Systems and Components" was established to launch and perform research projects related to safety issues concerning the extended interim storage of radioactive waste. For example, within our project LaMEP, we investigate ageing effects of metal and elastomer seals as well as polymeric neutron shielding materials, which are container components that fulfil major safety functions. The results of the experiments help to understand the long term behaviour of these components. Likewise, our project BRUZL started at BAM in 2018 with the aim of developing a fracture mechanics approach to understand and describe a potential brittle failure mechanism of fuel cladding during long-term interim storage. BAM also contributes to the GRS project "Development of methods and models and international exchange for safety evaluation in the frame of interim storage of radioactive waste". Additionally, BAM is involved in several international research programmes dealing with extended interim storage, such as the European Joint Programme on Radioactive Waste Management (EURAD), the Extended Storage Collaboration Program (ESCP) and IAEA Coordinated Research Projects. The present contribution provides a comprehensive overview of BAM research activities contributing to national and international gap analyses and to filling knowledge gaps regarding the safe long term management of radioactive waste. 2019 Annual Meeting on Nuclear Technology 978-3-926956-95-8 Annual Meeting on Nuclear Technology 2019 Berlin, Germany 07.05.2019 08.05.2019 1 5 2020-12-07 OPUS4-51490 Beitrag zu einem Tagungsband Zaghdoudi, Maha; Weber, Mike; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Numerical Modelling of Compression Stress Relaxation and Compression Set of Elastomer O-Ring During Aging Elastomer seals are used in many industrial applications due to their excellent mechanical properties at a wide range of temperatures. Their high versatility and recovery potential under several load conditions make them well suitable for the application in containers designed for transport, storage and/or disposal of radioactive materials. In containers for low and intermediate level radioactive waste, elastomer seals are used as barrier seals, and as auxiliary seals in storage and transportation casks (dual purpose casks) for heat generating radioactive waste, such as spent fuel and high-level waste. While a seal exchange at defined intervals is typical in many conventional applications, it is impossible or at least hard to perform when principles of minimization of radiation exposure have to be considered and prohibit an unnecessary cask handling. An extensive knowledge of the change of the elastomer's properties during aging and the availability of reliable end-of-lifetime criteria to guarantee the permanent safe enclosure of the radioactive material is mandatory. As BAM is involved in most of the national cask licensing procedures and in the evaluation of cask-related long-term safety issues, great efforts have been already made and are still planned to scientifically support this task. Compression stress relaxation and compression set were identified as key indicators of elastomer long-term performance and quantitatively investigated in comprehensive test programs. Among other representative types of elastomers, specimens made from ethylene propylene diene rubber (EPDM) were tested before, during and after aging to capture the most important of their complex mechanical properties. In the presented study, exemplary results were used to simulate the compression stress relaxation and the compression set of elastomer O-rings during aging. Regarding the influence of temperature, the time-temperature superposition principle is applied in the relaxation analysis of elastomer O-rings. The proposed model is implemented in the commercial finite element software ABAQUS/Standard® [1] with a sequential temperature displacement coupling. Numerical results match the experimental compression stress relaxation measurements well. The prediction of compression set values after long-term aging shows a relatively good agreement with the experimental results. Nevertheless, all input parameters derived from the specimen tests, additional assumptions concerning boundary conditions and modeling strategy are discussed with regard to the identified slight discrepancies. The possibility to extend the finite element model to represent the O-ring seal's ability to recover after a (fast) partial release is taken into account. ASME 2020 ASME 2020 Pressure Vessels & Piping Conference 978-0-7918-8388-4 ASME 2020 Pressure Vessels & Piping Conference (PVP2020) Online meeting 03.08.2020 PVP2020-21270 10.1115/PVP2020-21270 2020-11-02 OPUS4-51962 Buchkapitel Droste, Bernhard; Wolff, Dietmar; Bevilacqua, A.; Reiche, I.; Harvey, J.; Hirose, M.; Kumano, Y.; McConnell, P.; Saegusa, T.; Einziger, R. González-Espartero, A. Methodology for a Safety Case of a Dual Purpose Cask for Storage and Transport of Spent Fuel Spent nuclear fuel which is generated in the operation of nuclear reactors needs to be safely managed following its removal from the reactor core. On-site power reactor storage pools were designed on the assumption that after a short period of time spent nuclear fuel would be removed for reprocessing and disposal or further storage elsewhere. The amount of highly radioactive spent fuel that needs to be stored over longer periods of time is growing and additional storage capacity is required. One of the widely used options for additional storage capacity is the use of casks for dry storage of spent fuel. Among various existing dry storage concepts, several Member States are utilizing a concept of dual purpose casks (DPCs). This publication provides practical advice on the structure and contents of a DPC integrated safety case with reference to existing IAEA requirements relevant to the licensing and use of transport and storage casks for spent fuel. Vienna, Austria IAEA Publishing Section 2020 IAEA TECDOC SERIES 978-92-0-131620-2 1 109 2021-01-06 OPUS4-52289 Forschungsbericht Völzke, Holger; Herold, Christian; Wolff, Dietmar; Orellana Pérez, Teresa; Bollingerfehr, W.; Prignitz, S.; Wunderlich, A. Abschlussbericht zum FuE-Verbundvorhaben KoBrA: Anforderungen und Konzepte für Behälter zur Endlagerung von Wärme entwickelnden radioaktiven Abfällen und ausgedienten Brennelementen in Steinsalz, Tonstein und Kristallingestein Im Forschungsvorhaben KoBrA werden Anforderungen an Endlagerbehälter für hochradioaktive Abfälle erstmals systematisch und unter Berücksichtigung des internationalen Standes von Wissenschaft und Technik hergeleitet. Parallel werden die behälterrelevanten Randbedingungen und Beanspruchungsgrößen für Endlagerbehälter in den drei potenziellen Wirtsgesteinen Steinsalz, Tonstein und Kristallingestein ermittelt. Darauf aufbauend werden die zur Erfüllung der Anforderungen unter den gegebenen Einwirkungen und Beanspruchungen notwendigen Behälterfunktionen bestimmt und erste Konzeptideen für zukünftige Endlagerbehälter diskutiert bzw. entwickelt. Peine BGE Technology Bundesanstalt für Materialforschung und -prüfung (BAM) 2020 1 110 10.2314/KXP:1750909669 2021-03-17 OPUS4-43418 Beitrag zu einem Tagungsband Grelle, Tobias; Wolff, Dietmar; Probst, Ulrich; Jaunich, Matthias; Völzke, Holger Investigation programme for evaluation and prediction of the long-term behaviour of Helicoflex® metal seals In Germany, for the transport and storage of spent nuclear fuel, casks with double closure lid systems are used, which are equipped with Helicoflex® metal seals. The original interim storage period for these casks was planned to be 40 years. However, recent political developments indicate that a storage time of more than 80 years might be necessary. Therefore, the current storage licenses have to be renewed in due course, which requires extended knowledge of the long-term behaviour of all cask components. At the Bundesanstalt für Materialforschung und -prüfung (BAM), metal seals have been investigated after ageing at temperatures between room temperature and 150 °C for up to 7 years. At regular intervals the seals have been tested for leakage rate as well as for their mechanical behaviour. From these tests pronounced influence of ageing could be shown which results in the decrease of the seal force and the useable resilience. The main reason attributed to these performance changes is the increasing permanent deformation of the outer layer of the seal due to creep. So far, an explicit analytical description of the long-term behaviour that could be used for predictions exceeding the tested ageing times and temperatures was not suitable. In addition to the component tests that were already conducted, a comprehensive investigation programme has been started to describe the mechanical behaviour of the individual seal components. The individual seal components are tested regarding different material characteristics including creep, deformation and microstructural properties. The comparability of the material characterization is ensured by comparing the basic raw material of the specimen with the actual component material. Furthermore, detailed investigations of the time and temperature dependent deformation behaviour are realized by ageing seal segments at multiple temperatures for different periods of time and employing standardized tests. By analysing the acquired data in combination with the ongoing long-term component tests a dataset for analytical prediction of the long-term behaviour of the seals is intended for an extended period of time under a certain temperature regime. INFORUM Verlags- und Verwaltungsgesellschaft mbH 2017 48th Annual Meeting on Nuclear Technology (AMNT 2017) Proceedings 48th Annual Meeting on Nuclear Technology (AMNT 2017) Berlin, Germany 16.05.2017 17.05.2017 1 7 2018-02-19 OPUS4-43248 Buchkapitel Kömmling, Anja; Wolff, Dietmar; Jaunich, Matthias van Breugel, K.; Koleva, D.; Beek, T. Investigation of long-term behaviour of elastomeric seals for transport and storage packages Elastomers are widely used as the main sealing materials in Containers for low- and intermediate-level radioactive waste and as an additional component fo metal seals in spent-fuel and high-level waste containers. According to appropriate guidelines and regulations, safe enclosure of the radioactive container contents has to be guaranteed for lengthy storage periods of at least 40 years. Therefore, the understanding of seal ageing behaviour is of high importance and has to be considered with regard to possible dynamic events taking place during transport after storage. An accelerated ageing approach for compressed seals is presented, as well as some first results. Springer 2018 The Aging of Materials and Structures - Towards Scientific Solutions for the Ageing of Our Assets 978-3-319-70192-9 17 25 10.1007/978-3-319-70194-3_2 2017-12-04 OPUS4-40411 Beitrag zu einem Tagungsband Völzke, Holger; Wolff, Dietmar Update on the German approach of storing spent nuclear fuel in dual purpose casks until final disposal The German approach of storing spent nuclear fuel in dual purpose casks until final disposal is based on individually licensed storage sites concerning specific nuclear inventories and dual purpose cask types. The currently approved license period is maximum 40 years. With nuclear policy changes including the phase-out decision of 2011 and a new approach for the HLW repository siting process set up 2013 by law also the spent fuel and HLW management strategy has to be adapted. This includes the timely development of disposal container concepts as part of the overall repository siting process and the need for longer interim storage periods until final disposal. Other aspects affect new regulations about the financing of the nuclear waste management by the industry and the public sector, the restructuring of responsible authorities in 2016/2017 and the adaption of R&D funding programs addressing also pre-disposal (or extended interim storage) issues. BAM as a Federal Research Institute has been responsible for or in charge of container safety Evaluation for transport and storage casks for radioactive waste for several decades and started addressing potential Extended interim storage issues already several years ago. This included participation in international projects at the IAEA or in the U.S. Extended Storage Collaboration Program (ESCP) as well as long term laboratory tests with metal seals, elastomeric seals and polymers for neutron shielding purposes. Test results of BAM are published regularly and gained data provide valuable information about thermo-mechanical and radiological degradation effects as well as the long term Performance of respective cask components. Regarding the reliable extrapolation and prediction of the long term Performance of cask materials and components for time periods of up to 80 or even 100 years the continuation and extension of laboratory tests and the development of analytical and numerical simulation models and tools is essential and under way. American Nuclear Society, Inc. 2017 Proceedings of the 16th International High -Level Radioactive Waste Management Conference (IHLRWM 2017) 16th International High -Level Radioactive Waste Management Conference (IHLRWM 2017) Charlotte, NC, USA 09.04.2017 13.04.2017 189 194 2017-05-30 OPUS4-40412 Beitrag zu einem Tagungsband Orellana Pérez, Teresa; Völzke, Holger; Wolff, Dietmar; Zencker, Uwe Cladding considerations at BAM regarding extended storage spent fuel With the clear expectation of the need for extending spent fuel storage in Germany beyond the initial license period of maximum 40 years additional material data and knowledge about the long term performance and integrity of casks and internals like fuel rods will be required to meet major safety goals and regulatory requirements. Based on a broad knowledge base about fuel cladding behavior, degradation mechanisms and related potential failure mechanisms, e. g. induced by reoriented Hydride precipitation, as illustrated in this paper, a specific gap analyses for the German situation regarding fuel conditions and cladding materials should identify the specific knowledge gaps to be addressed and closed in the near future. This is of specific interest as all spent fuel assemblies are going to be transferred to dry cask storage with the next decade and as a consequence of the German nuclear phase-out decision. Within several decades, BAM as a Federal materials research institute gathered a broad range of expertise in the safety evaluation of materials, components and casks under operational and accidental thermal and mechanical conditions. This paper elucidates selected Basic considerations regarding technical and scientific knowledge about the long term aging performance and potential failure mechanisms of fuel cladding materials. Under consideration of the national R&D funding policy which has been adapted to the extended interim storage or pre-disposal needs and the competences of BAM, its future R&D strategy is explained and some R&D objectives have already been identified. BAM will continue and expand ist engagement in the area of investigating fuel cladding material behavior in the long term and developing validated simulation and analyses tools in collaboration with national and international partners. R&D outcomes shall improve the knowledge-base to close identified knowledge gaps in the area of demonstrating fuel cladding integrity and to provide crucial information with regard to future safety assessments for the extended interim spent fuel storage. American Nuclear Society, Inc. 2017 Proceedings of the 16th International High-Level Radioactive Waste Management Conference (IHLRWM 2017) 16th International High -Level Radioactive Waste Management Conference (IHLRWM 2017) Charlotte, NC, USA 09.04.2017 13.04.2017 718 725 2017-05-30 OPUS4-40391 Beitrag zu einem Tagungsband Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Characterisation of degradation and determination of end-of-lifetime criterion for O-ring seals The ageing of polymers, including elastomers, is an undesirable but inevitable process leading to a limited lifetime of rubber products such as seals. Independent of the application, as e.g. in automotive, piping or container applications, a long lifetime or at least a timely exchange of a seal before occurrence of critical failure is desired. In order to investigate the degradation of material properties and to determine the lifetime of elastomers used as seals, an ageing programme was started with hydrogenated acrylonitrile butadiene rubber (HNBR), ethylene propylene diene rubber (EPDM) and fluorocarbon rubber (FKM) [1-3]. Both O-ring seals (uncompressed and compressed by 25 %) with a cord diameter of 10 mm as well as sheets with a thickness of 2 mm were aged at 75 °C, 100 °C, 125 °C and 150 °C for up to two years. The changes of material properties during ageing were characterised for each material using samples from the sheets by means of e.g. Dynamic Mechanical Analysis and tensile tests, while sealing properties such as leakage rate were determined on O-rings. The experimental results indicate that while material properties show considerable degradation effects, the static leakage rate stays constant or even decreases before failure occurs quite suddenly at advanced degradation levels. This reveals that static leakage rate has only limited sensitivity for the degradation of the seal material. Our approach to determine a suitable end of lifetime criterion, which involves a partial decompression of the seal during the leakage test, is presented and discussed. 2017 RubberCon 2017 978-80-906662-0-7 RubberCon 2017 Prague, Czech Republic 23.05.2017 25.05.2017 65 72 2017-05-29 OPUS4-40300 Beitrag zu einem Tagungsband Völzke, Holger; Wolff, Dietmar Spent Nuclear Fuel and HLW Storage towards Disposal - Challenges and Perspectives of an Integrated Approach - 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. The Japan Society of Mechanical Engineers 2016 PATRAM 2016 The 18th International Symposium on the Packaging and Transportation of Radioactive Materials - Proceedings 978-4-88898-270-2 PATRAM 2016 The 18th International Symposium on the Packaging and Transportation of Radioactive Materials Kobe, Japan 18.09.2016 23.09.2016 Paper 5006 2017-05-22 OPUS4-40301 Vortrag Völzke, Holger; Wolff, Dietmar Spent Nuclear Fuel and HLW Storage towards Disposal - Challenges and Perspectives of an Integrated Approach - 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. 2016 PATRAM 2016 The 18th International Symposium on the Packaging and Transportation of Radioactive Materials Kobe, Japan 18.09.2016 23.09.2016 2017-05-22 OPUS4-40303 Vortrag Völzke, Holger; Wolff, Dietmar Update on the German approach of storing spent nuclear fuel in dual purpose casks until final disposal The safe and secure long term storage of spent nuclear fuel until its final disposal in a deep geological repository is a corner stone of the German nuclear waste management strategy. So far interim storage licenses are limited to 40 years concerning the initial concept of having a repository available until 2035. But in the meantime the exploration of the designated Gorleben salt dome was finally stopped and a reset of the complete site selection process was concluded by the German Federal parliament and subsequently fixed by law. A 33-member "Commission on the storage of highly radioactive materials" was established in 2014, to elaborate a consent based siting process and to develop criteria for the safe disposal of heat generating waste. The disposal commission agreed and published its final report in 2016. As a major consequence, the necessary timeframe for establishing the final repository is going to be exceeded significantly and with that, an extension of the current dry interim storage in dual purpose casks becomes necessary. This paper explains the major actions to be taken in Germany to address all relevant issues for a future extension of storage licenses beyond the initial timeframe of 40 years. 2017 ANS Conference International High-Level Radioactive Waste Management (IHLRWM) 2017 Charlotte, NC, USA 09.04.2017 13.04.2017 2017-05-22 OPUS4-39870 Beitrag zu einem Tagungsband Jaunich, Matthias; Hagenow, Peter; Kasparek, Eva Maria; Kömmling, Anja; Noack, Volker; Völzke, Holger; Wolff, Dietmar Requirements for the use of elastomer seals in casks for final disposal of low and intermediate level waste Elastomer seals are widely used as barrier seals in containers for low and intermediate level radioactive waste and in some countries for spent fuel transportation casks. Depending on the area of use, the rubber materials have to demonstrate proper sealing performance with regard to mechanical, thermal and environmental conditions as well as irradiation during the entire operation period. In Germany the low and intermediate level radioactive waste is planned to be disposed in the Konrad repository in standardized containers. Many of these containers use an elastomer seal between lid and container body. Depending on the radiactive inventory and a possible containment of the waste in inner barrels and/or concrete structures, such containers may require a specific leak tightness. In such cases, specified leakage rates are shall not be exceeded by the the seals to keep potential activity releases from the inventories well below defined limits. Generally, all waste containers have to fulfill the waste acceptance criteria for the Konrad repository as defined by the reports BfS SE-IB-29/08 and SE-IB-30/08. From these criteria several requirements for seal performance are derived. The seals have to: - ensure full functionality until final container disposal, - maintain its function in case of a thermal or mechanical accident, - ensure encapsulation also at -20 °C. This combination of requirements is challenging especially as a seal exchange, which is typical for many other applications, is hardly possible and thus a sound understanding of how to perform safety evaluation of containers is required. Therefore BAM has initiated investigations on elastomer seal behaviour. This work focuses on low temperature behaviour and sealing performance concerning static conditions as well as partial loss of compression and ageing of elastomer seals. Concerning ageing, property changes caused by long-term thermooxidative conditions as well as gamma irradiation are investigated. This contribution presents an overview and explanation of the aims of the ongoing research and gives an update of the most relevant results. 2017 KONTEC 2017 13th Internationales Symposium "Konditionierung radioaktiver Betriebs- und Stillegungsabfälle Dresden, Germany 22.03.2017 24.03.2017 595 601 2017-04-19 OPUS4-45844 Beitrag zu einem Tagungsband Grelle, Tobias; Probst, Ulrich; Jaunich, Matthias; Skrotzki, Birgit; Wolff, Dietmar Creep investigations on aluminum seals for application in radioactive waste containers In Germany spent nuclear fuel and high level radioactive waste is stored in interim storage containers with double lid systems. Those lids are equipped with metal seals (e.g. Helicoflex®) that ensure the safe enclosure of the inventory. The used metal seals consist of three components as can be seen in the cross-sectional view in Figure 1. The innermost part is a helical spring that is surrounded by an inner jacket made of stainless steel. The outer jacket that is made of a softer material which in case of assembly in the aforementioned storage containers is silver or aluminum (i.e. Al 99.5). During application the seal is compressed and due to the restoring force of the helical spring, the outer jacket is plastically deformed and adapts to the sealing surface. Hence, leakage paths are closed and the sealing function is generated. In Germany the above-mentioned containers are licensed for up to 40 years of interim storage, which in case extended storage becomes necessary before a final repository is available will have to be extended to even longer periods. Therefore, the evaluation of the long-term behavior of the seals is necessary, taking into account storage conditions, decay heat and possible mechanical loads as well. At Bundesanstalt für Materialforschung und -prüfung (BAM) long-term investigations are being conducted in which seals are assembled in test flanges and aged at temperatures ranging from room temperature to 150°C for accelerated aging. The aged seals are tested semi-annually (after the first 6 months in which the seals are tested more frequently) regarding the sealing performance, the remaining seal force, and the useable resilience upon decompression. Results of these investigations have been published over the past years (e.g. Grelle, Wolff, Probst, Jaunich, & Völzke, 2017; Völzke, Wolff, Probst, Nagelschmidt, & Schulz, 2014). It was found that the seal force and the useable resilience decrease with time and temperature, which is in agreement with the result of other studies (Sassoulas et al., 2006; Wataru et al., 2016) as well. Geometry change of the outer jacket has been identified as the main reason for this seal behavior. At the prevailing operating temperatures and stresses the aluminum is subjected to creep deformation leading to a thinning of the outer jacket. Since the seal groove depth remains unchanged the helical spring expands, which in turn leads to a decrease of the generated spring and seal force. Although the main reason for the change of seal parameters over time and temperature is known, a detailed characterization of the seal behavior and a reliable prediction of the parameter development for aging times that exceed the experimental time frame have not been possible, yet. For deeper understanding of the aging processes, an Investigation program, which is covered in this contribution, is conducted at Bundesanstalt für Materialforschung und -prüfung (BAM) that focusses on the behavior of the aluminum jacket and its influence on the long-term sealing performance. The program investigates properties of material samples as well as the behavior of the seal as a component. Original sheet material of the same aluminum that is used for manufacturing of the seals is investigated in compression creep tests. For this, a DMA (dynamic mechanical analysis) machine is employed (here used for static tests) that allows for a measurement of the specimens deformation under forces of up to 500 N. The advantage of this method is that the original material can be tested in the same shape as used for the seals which is 0.5 mm thick sheet material. For investigation of tensile creep standard specimens are used, that were machined from surrogate material of the same composition and annealing condition. Furthermore, aluminum seals that are cut into smaller segments are assembled in flanges and placed in heating chambers at temperatures ranging from 23°C to 150°C. After different periods of time from 3 days to 300 days the segments are taken out of the flanges and are investigated, thus giving information on different states of aging. Measurements of the development of the seal contact width and the aluminum jacket thickness are done with an optical microscope. Further investigations on the segments will include metallography and hardness measurements. From the detailed material and component behavior including the results of the long-term seal force and useable resilience investigations a better understanding of the overall seal behavior can be gained. The aim is to contribute to the development of material models and analytical approaches for the prediction of the sealing behavior in dependence of time and temperature. 2018 Proceedings of the International Conference on Aluminum Alloys 2018 978-1-926872-41-4 International Conference on Aluminum Alloys Montreal, Canada 17.06.2018 1 2 2018-09-05 OPUS4-41312 Vortrag Wolff, Dietmar Long-term behavior of metal and elastomer seals as well as polyethylene as safety relevant components of transport and storage casks for radioactive materials (LaMEP) In Germany, the concept of dry interim storage in dual purpose metal casks before disposal is being pursued for spent nuclear fuel (SNF) and high level waste (HLW) management. The main safety relevant components are the thick-walled dual purpose metal casks. These casks consist e.g. of a monolithic cask body with integrated neutron shielding components (polymers, e.g. polyethylene) and a monitored double lid barrier system equipped with metal and elastomer seals. The metal seals of this bolted closure system guarantee the required leak-tightness whereas the elastomer seals allow for leakage rate measurement of the metal seals. This presentation provides an overview of BAM proactive R&D projects related to the long-term behavior and degradation effects of metal seals, elastomer seals and polyethylene used as neutron shielding material. Particular attention is paid to the approach and first results of the third-party-founded research project LaMEP with the aim of further closure of existing knowledge gaps of safety relevant aging effects of such cask components. 2017 Symposium Verlängerte Zwischenlagerung Garching (Munich), Germany 22.06.2017 23.06.2017 2017-08-14 OPUS4-42399 Zeitschriftenartikel Kömmling, Anja; Chatzigiannakis, E.; Beckmann, Jörg; Wachtendorf, Volker; von der Ehe, Kerstin; Braun, Ulrike; Jaunich, Matthias; Schade, U.; Wolff, Dietmar Discoloration Effects of High-Dose gamma-Irradiation and Long-Term Thermal Aging of (U) HMW-PE Two polyethylene types with ultra-high (UHMWPE) and high molecular weight (HMW-PE) used as neutron radiation shielding materials in casks for radioactive waste were irradiated with doses up to 600 kGy using a 60Co gammasource. Subsequently, thermal aging at 125∘C was applied for up to one year. Degradation effects in the materials were characterized using colorimetry, UV-Visspectroscopy, IR spectroscopy, and DSC. Both materials exhibited a yellowing upon irradiation.The discoloration of UHMW-PE disappeared again after thermal aging.Therefore, the yellowing is assumed to originate fromannealable color centers in the formof free radicals that are trapped in the crystalline regions of the polymer and recombine at elevated temperatures. For the antioxidantcontaining HMWPE, yellowing was observed after both irradiation and thermal aging. The color change was correlated mainly to decomposition products of the antioxidant in addition to trapped radicals as in UHMW-PE. Additionally, black spots appeared after thermal aging of HMW-PE. Hindawi 2017 International Journal of Polymer Science 2017 Article ID 1362491 1 10 urn:nbn:de:kobv:b43-423992 10.1155/2017/1362491 http://creativecommons.org/licenses/by/3.0/de/deed.de 2017-10-09 OPUS4-42844 Beitrag zu einem Tagungsband Subramani Bhagavatheswaran, E.; Wießner, S.; Jaunich, Matthias; Wolff, Dietmar Einfluss der Alterung auf dichtungsrelevante Eigenschaften von FKM-, VMQ- und EPDM-Elastomeren Da Elastomere in vielfältigen Dichtungsanwendungen eingesetzt werden und dabei teilweise großen Einfluss auf die Funktionsfähigkeit und Sicherheit haben, ist der Einfluss der Alterung auf dichtungsrelevante Eigenschaften relevant. Eine strukturierte Untersuchung des Einflusses von verschiedenen Mischungsrezepturen auf die Bauteileigenschaften, das Alterungsverhalten und die Funktion wird vorgestellt. 2017 Technomer 2017 2017 978-3-939382-13-3 Technomer 2017 Chemnitz, Germany 09.11.2017 10.11.2017 41 41 2017-11-16 OPUS4-42845 Beitrag zu einem Tagungsband Jaunich, Matthias; Grelle, Tobias; Goral, Milan; Wolff, Dietmar Gehde, M.; Wagenknecht, U.; Bloß, P. Further investigations on the low temperature performance of rubber seals For many sealing applications low temperature performance is required. The overall understanding of the relevant influences on low temperature performance of rubber seals are summarized and the currently running investigations described. The correlation of the physical material properties with seal performance is studied. This includes as well purely static sealing applications as the performance during/after fast partial relief of seals at low temperatures. 2017 Technomer 2017 2017 978-3-939382-13-3 Technomer 2017 Chemnitz, Germany 09.11.2017 10.11.2017 40 40 2017-11-16 OPUS4-42849 Beitrag zu einem Tagungsband Subramani Bhagavatheswaran, E.; Wießner, S.; Jaunich, Matthias; Wolff, Dietmar Aging study and electrical resistance based stress-monitoring of rubber seals Elastomer seals are widely used as barrier seals in containers for low and intermediate level radioactive waste. In addition, they are also used in waste fuel storage and transportation casks as auxiliary seals. Depending on the area of use, the rubber materials have to demonstrate proper sealing performance with respect to mechanical, thermal and environmental conditions as well as irradiation during the entire operation period. A fundamental understanding of the structure property relationship and their changes during aging can help to evaluate the long-term sealing performance. In the present study, specific materials are investigated to study the structure-property and seal performance-correlation. Fluoro-elastomer (FKM), silicone rubber (VMQ) and ethylene propylene diene rubber (EPDM) were chosen as base rubbers. Comparable mechanical properties for these seals, especially in terms of a comparable compression behavior were achieved by careful control of base rubber formulation, i.e., by opting for the right filler and its concentration, amount of crosslinking chemicals, and with the assistance of process oils. Moreover, with the same rubber, similar mechanical properties were achieved by varying the filler concentration and crosslinking degree, which shall enable to correlate the particular influence on the structure property dependency of the seals in detail. The materials are investigated under pristine and aged conditions to evaluate the influence of aging, e.g. on the stress relaxation or recovery behavior. These values appear to be suitable parameters to judge the expected sealing performance. Due to the electrically conducting nature of some fillers used to reinforce rubbers (such as carbon blacks, carbon nanotubes (CNTs), Graphene, etc.) it is possible to obtain current information about mechanical and visco-elastic properties by monitoring the electrical conductivity or resistivity. A simple relation that relates electrical resistance with mechanical stress was derived and the stress values were theoretically predicted from the electrical resistance values, which showed good correlation with experimental results. 2017 192nd Technical meeting of the ACS Rubber Division 2017 192nd Technical meeting of the ACS Rubber Division Cleveland, OH, USA 09.10.2017 12.10.2017 1 25 2017-11-16 OPUS4-42941 Zeitschriftenartikel Kömmling, Anja; von der Ehe, Kerstin; Wolff, Dietmar; Jaunich, Matthias Effect of high-dose gamma irradiation on (U)HMWPE neutron shielding materials High and ultra-high molecular weight polyethylenes were gamma-irradiated with doses up to 600 kGy. The changes in the material properties were analysed using DSC, DMA, IR spectroscopy, as well as measurements of density and insoluble content. The irradiation led to an increase of the degree of crystallinity because of chain scissions during irradiation, leading to shorter and thus more mobile chains. Both the plateau value of the shear modulus G′ and the insoluble content increased with Irradiation dose, indicating the formation of additional crosslinks. Furthermore, IR spectroscopy revealed irradiation induced oxidation and the formation of double bonds, indicating that some of the hydrogen atoms responsible for the neutron shielding capability have been released. Elsevier 2018 Radiation Physics and Chemistry 142 29 33 10.1016/j.radphyschem.2017.02.014 2017-11-17 OPUS4-46346 Beitrag zu einem Tagungsband Jaunich, Matthias; Kömmling, Anja; Horn, Jutta; Völzke, Holger; Wolff, Dietmar Long-Term Performance of Elastomer seals - From Aging Tests to Lifetime Estimations Elastomers show a high versatility which makes them ideal materials for sealing applications in various fields. Especially under changing application conditions the high recovery potential of this class of material is beneficial to compensate temperature or pressure fluctuation, and geometrical changes resulting from mechanical loads in e.g. accident conditions. Out of these reasons elastomers are also used in containers for low and intermediate level radioactive waste and for spent fuel transportation casks. In casks designed for low and intermediate level waste elastomer seals can act as primary seal responsible for the containment function whereas in spent fuel storage and transportation casks (dual purpose casks (DPC)) elastomer seals are used as auxiliary seals to allow leakage rate measurements of metal barrier seals. An inherent prerequisite for this kind of application is the Long time-scale of operation without or with limited possibility of seal replacement. In Germany an interim storage license for DPC`s is typically issued for 40 years, a timeframe which might increase in the future due to challenges of the final repository siting procedure. For low and intermediate level waste, also long time periods are required before final disposal can be achieved. Therefore, the performance of elastomer seals over extended time periods is, as for other applications, of high importance. A typical approach to ensure long-term functionality is to perform accelerated aging tests to calculate an estimated lifetime by assuming e.g. Arrhenius like equations for the timetemperature relationship. This approach requires a suitable end of life criterion considering the application of interest. This often can represent a challenge on its own. As BAM is involved in most of the cask licensing procedures and especially responsible for the evaluation of cask-related long-term safety issues we initiated several test programs for investigating the behavior of elastomer seals. Experiments concerning the low temperature performance down to -40 °C and the influence of gamma irradiation have been started first. Currently the thermal aging behavior of elastomer seals, which is the topic of this contribution, is examined. For our aging investigations we use a broad approach to first determine the property changes in different elastomer materials due to thermo-oxidative aging at elevated temperatures and secondly, we test how the typical methods of lifetime extrapolation can be applied to these results. This Approach enables us to detect and exclude undesired side effects which very often influence lifetime estimations. In this contribution, our recent results are extended. The results show that lifetime estimation based on single material properties can be misleading and therefore a combination of several methods is recommended. 2018 Proceedings of the ASME 2018 Pressure Vessels an Piping Conference PVP2018 ASME 2018 Pressure Vessels and Piping Conference Prague, Czech Republic 15.07.2018 20.07.2018 84631-1 84631-8 2018-10-24 OPUS4-40611 Beitrag zu einem Tagungsband Grelle, Tobias; Wolff, Dietmar; Probst, Ulrich; Jaunich, Matthias; Völzke, Holger Material investigation and long-term sealing behavior of Helicoflex® metal seals used in containers for spent nuclear fuel In Germany spent nuclear fuel is stored and transported in casks that possess bolted lid systems equipped with double jacket metal seals of Helicoflex® type in order to enable safe enclosure of the radioactive inventory. A dry interim storage period of 40 years was planned and the casks are licensed for that time span. However, due to political reasons and delayed disposal projects this time span is expected to increase significantly. It is therefore necessary to evaluate the long-term sealing behavior of the casks exceeding 40 years of operating time. In this paper, we discuss our approach to investigate the aging behavior of such metal seals, and to predict the long-term sealing behavior. Accelerated aging component tests with seals are performed at temperatures up to 150°C to investigate the course of seal force, useable resilience and leakage rate. Even though these tests have already shown a significant decrease in seal force and useable resilience after aging times of less than 1 year, for most seals the leakage rate stayed better than the specified value. However, observation of the leakage rate has to be continued to determine the aging effect on the seal properties. As a main influence on the seal long-term behavior the increasing permanent deformation of the outer jacket has been recognized. It is made of aluminum or silver which means that the temperatures that are relevant for the aforementioned application in casks lead to creep deformation. For further investigation of seal behavior a comprehensive research program concerning the material characteristics and aging behavior of the individual seal components, with an emphasis on the outer jacket material, has been launched. The aim is to get a better understanding of the time and temperature dependent creep mechanisms and deformation. The examinations are separated into tests on seal segments and tests on standardized specimen. In order to be able to study the aging process, seal segments are compressed in flanges and stored at temperatures ranging from room temperature to 150°C. After defined time intervals the segments are analyzed by using standardized tests including structure investigation and creep tests. The results are compared with the behavior of the specimen basic raw material. This is done to ensure comparability of the thin jacket material and additional sheet material used for standardized tests. Thus, the prediction of component changes after different aging times at different temperatures can be made. As a result forecasts on the long term seal behavior are intended. 2017 Waste Management Symposia 2017 Proceedings 978-0-9828171-6-2 Waste Management Symposia Phoenix, AZ, USA 05.03.2017 Article 17135, 1 8 2017-06-16 OPUS4-41167 Buchkapitel Jaunich, Matthias; Kömmling, Anja; Wolff, Dietmar Grellmann, W.; Langer, B. Investigations of elastomeric seals - Low temperature performance and aging behavior Due to their simple and reliable application, elastomers are used for many tasks. Many fields of application like transport, aviation and process technology, entail low temperatures where proper functionality of the employed seals has to be ensured. Therefore, understanding the low temperature behavior of elastomeric seals is important for safe seal operation to restrict the temperature application range. For all areas of application, the question of seal lifetime is also important for replacement or maintenance intervals. The lifetime is especially important in applications that allow no seal replacement. Since the seal can determine the lifetime of storage in such cases, reliable lifetime estimation is necessary for these applications, and requires an extensive knowledge of the specific aging behavior. Springer Verlag 2017 Deformation and Fracture Behaviour of Polymer Materials 247 978-3-319-41877-3 431 443 10.1007/978-3-319-41879-7_30 2017-07-31 OPUS4-40958 Zeitschriftenartikel Kömmling, Anja; Jaunich, Matthias; Pourmand, P.; Wolff, Dietmar; Gedde, U.W. Influence of ageing on sealability of elastomeric O-rings At BAM, which is the federal institute for materials research and testing in Germany, it is one of our tasks to evaluate the safety of casks designed for transport and/or storage of radioactive material. This includes the assessment of the service lifetime of elastomeric seals that are part of the container lid system with regard to the requirements for long-term safety (40 years and more) of the containers. Therefore, we started an accelerated ageing programme with selected rubbers often used for seals (HNBR, EPDM and FKM) which are aged at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) up to 1.5 years. In order to assess sealability, O-rings are aged in compression by 25 % (corresponding to the compression during service) between plates as well as in flanges that allow leakage rate measurements. For comparison, uncompressed O-rings are aged as well. Further methods characterising seal performance are compression stress relaxation (CSR) reflecting the loss of sealing force of a compressed seal over time, and compression set (CS) which represents the recovery behaviour of a seal after release from compression. Additionally, hardness is measured for information about the change of mechanical properties. The experimental results indicate that while hardness, CSR and CS show considerable degradation effects, the leakage rate stays relatively constant or even decreases until shrinkage combined with the loss of resilience of the aged seal leads to leakage. This demonstrates that static leakage rate, which is the only available direct seal performance criterion, has only limited sensitivity towards the degradation of the seal material. CS data is extrapolated using time-temperature shifts and Arrhenius graphs. An exemplary CS of 50 % would be reached after approx. 1.2, 17 and 29 years at 60 °C for HNBR, EPDM and FKM respectively. Weinheim WILEY-V C H VERLAG GMBH 2017 Macromolecular Symposia 373 PolymerTec 2016 Merseburg, Germany 15.06.2016 17.06.2017 1 UNSP 1600157, 1 10 10.1002/masy.201600157 2017-07-11 OPUS4-46110 Beitrag zu einem Tagungsband Grelle, Tobias; Wolff, Dietmar; Probst, Ulrich; Jaunich, Matthias; Völzke, Holger Investigation of the time and temperature dependent behavior of metal seals in radioactive waste containers The Bundesanstalt für Materialforschung und -Prüfung (BAM) runs an investigation program on the long-term behavior of multi-component metal seals. Such seals are used in a wide area of applications including transport and storage casks for spent nuclear fuel and high level radioactive waste. The seal function is mainly based on the compression of the inner helical spring, which generates the necessary seal force to keep the sealing surfaces in close contact. This in turn leads to a plastic deformation of the outer jacket of the seal, comprised of highly ductile aluminum or silver that adapts to the sealing surfaces of cask body and bolted lid, thus providing high Level leak tightness. In Germany, those casks are licensed for Interim storage periods of up to 40 years or more if extended Interim storage would become necessary before a final repository is available. Thus, the sealing performance has to be evaluated, including factors like elevated temperature due to decay heat or mechanical loads due to transport under normal as well as accident conditions. Long-term investigations at BAM have been running over the last nine years to identify and evaluate the seal performance by measuring the remaining seal force, the useable resilience and the leakage rate after various time intervals at temperatures ranging from room temperature up to 150 °C. It was found that the seal force and useable resilience decrease with time and temperature, caused by creep deformation of the outer jacket. In order to obtain an analytical description for the seal behavior and to achieve more information on the material behavior under application conditions a comprehensive investigation program with Focus on aluminum as outer jacket material was launched. The program includes material investigations such as compression and tension creep tests with representative basic materials. An additional test setup allows for the continuous measurement of the remaining seal force at temperatures of up to 150 °C. Furthermore, seal segments are compressed and stored in heating chambers, thus producing segments at different stages of the aging process. The segments are investigated regarding the development of the contact area width, jacket thickness and microstructural changes. This data will be used to develop material models and an analytical description of the time and temperature dependent long-term sealing behavior. This paper explains the current status of gained test results and modelling approaches and closes with an outlook to the future Project plans. 2018 Proceedings of the ASME 2018 Pressure Vessels an piping Conference ASME 2018 Pressure Vessels and Piping Conference Prague, Czech Republic 15.07.2018 20.07.2018 PVP2018-84584, 1 6 2018-10-02 OPUS4-47693 Buchkapitel Wolff, Dietmar; Bevilacqua, A.; Carlsen, B.; Chiguer, M.; González-Espartero, A.; Grahn, P.; Saegusa, T.; Sampson, M.; Seelev, I.; Wasinger, K.; Waters, M. González-Espartero (IAEA), A. Storing spent fuel until transport to reprocessing or disposal Spent fuel storage periods well beyond those originally foreseen are a reality. This publication offers several ideas and approaches that may be considered to address the increasingly longer storage times. The aim is to raise awareness, encourage dialogue and provide ideas on how to manage spent fuel. Key messages include the following: - Delays in reprocessing or disposal could result in spent fuel being stored for 100 years or longer. Safe, secure and effective storage of spent fuel manages fuel degradation while preserving future fuel cycle options. - Ageing management programmes apply engineering, operations and maintenance actions to ensure safety is maintained during storage, future handling and transport. - Site selection and facility and equipment design can significantly reduce the risks and costs of spent fuel storage over longer periods. - Spent fuel storage configurations can be selected to accommodate uncertain storage periods, to facilitate ageing management and to provide flexibility needed to accommodate the uncertainty of future end points, such as reprocessing or disposal. - By considering multiple licence renewals, regulatory frameworks can be designed to ensure safe storage until an acceptable end point is achieved. - Safety can be assured by maintaining shielding, containment, decay heat removal and criticality control. Navigating the complexity of societal beliefs and values, as well as political systems, has proven to be a greater challenge for the management of spent fuel than maintaining its safety and security or addressing the technical and economic aspects. - Sustainable spent fuel management requires policies and strategies to provide a clear, consistent and stable direction because they drive the need for spent fuel storage as well as the available options and timing for achieving an acceptable end point. Unless States address spent fuel reprocessing and disposal on a sufficient scale to accommodate their spent fuel discharges, then storage for longer and longer periods becomes the de facto end point — which is not considered to be consistent with the responsibility to protect human health and the environment. An effective, periodic licence renewal process can ensure effective ageing management and strong institutional control. Hence, spent fuel can be safely and securely stored for as long as it may be necessary until transport for reprocessing or disposal. However, the risks and costs of storing the growing inventory of spent fuel will continue to increase; and in the absence of an end point, it will eventually become a significant societal burden. Wien, Austria IAEA Publishing Section 2019 IAEA NUCLEAR ENERGY SERIES No. NF-T-3.3 978-92-0-100719-3 1 54 2019-04-01 OPUS4-47669 Buchkapitel Völzke, Holger; Wolff, Dietmar Saegusa, T.; Sert, G.; Völzke, Holger; Wille, Frank Long-term metal seal performance 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. Singapore World Scientific 2018 Basic of Transport and Storage of Radioactive Materials 978-981-3234-03-1 Chapter 20, 293 303 2019-04-01 OPUS4-57707 Beitrag zu einem Tagungsband Zaghdoudi, Maha; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar; Albouy, P.-A.; Häcker, Ralf; Stock, Daniel Overview of ongoing research and future prospects on polyethylene neutron shielding materials at bam The extension of the interim storage period of radioactive waste before disposal will cause additional challenges for the nuclear waste management in Germany, so that an extensive knowledge of the long-term performance of casks, including their components and inventories, will be required for future extended storage licenses. Ultra-high and high molecular weight polyethylenes ((U)HMW-PE) are used for neutron shielding purposes in casks for storage and transport of spent fuel and high-level waste due to their extremely high hydrogen content. During their service life of several decades as cask components, the PE materials are exposed to neutron and gamma radiation from the radioactive inventory of the casks, mechanical assembling stresses and temperature. All these combined effects affect the material properties of such components which in turn may be crucial for some possible accident scenarios. At the Bundesanstalt für Materialforschung und -prüfung (BAM), the effects of high temperature exposure in combination with subsequent or previous irradiation were investigated with a comprehensive aging program including thermal aging at 125 °C for different aging periods up to 5 years and irradiation with doses ranging from 50 to 600 kGy. This contribution provides an overview of the ongoing research related to the structural changes of (U)HMW-PE induced by gamma irradiation and high temperature exposure and focuses on current research perspectives at BAM with regard to the prediction of the dynamic behavior of the material during extended interim storage in case of an accident scenario. First results of the coupled effect of temperature, radiation and mechanical loading will be presented. The effect of microstructural changes induced by gamma irradiation and high temperature on the mechanical behavior of (U)HMW-PE will be assessed. 2023 PATRAM22 PATRAM22 Juan-Les-Pins, Antibes, France 11.06.2023 15.06.2023 1 10 2023-06-19 OPUS4-57369 Zeitschriftenartikel Zaghdoudi, Maha; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Understanding the recovery behaviour and the degradative processes of EPDM during ageing Recovery is an important measure for seal applications representing to which extent the elastomer regains its initial shape after deformation and release of an applied force. Compression set (CS) indicates the degree of recovery. Ethylene propylene diene rubber (EPDM) was aged at 75 ◦C, 100 ◦C, 125 ◦C and 150 ◦C for different ageing times up to five years and compression set measurements were performed at different times after disassembly and after additional tempering. Short- and long-term recovery up to one year after release for samples aged at 125 ◦C and 150 ◦C was also studied. To assess the curvature in the Arrhenius diagram that may occur due to non-sufficiently aged specimens, a degradation-rate based model was fitted to the CS data after tempering. For each ageing temperature, two decay fit functions were proposed, each with an activation energy and a corresponding degradative process. The influence of ageing on the leak-tightness after fast small partial release is investigated and estimated through the analysis of the shift factors from time temperature superposition (TTS) of CS measurements at different times after disassembly. Shift factors of CS measurement after 1 s and after additional tempering are in good agreement. Elsevier Ltd. 2023 Polymer Testing 121 107987 urn:nbn:de:kobv:b43-573699 10.1016/j.polymertesting.2023.107987 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2023-04-24 OPUS4-57370 Beitrag zu einem Tagungsband Zaghdoudi, Maha; Weber, Mike; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Simulation of compression set of epdm o-rings during aging It is common practice in the application of finite element analysis to model compression set (CS) of elastomers during aging with two different material models according to the two-network theory of Tobolsky. The theory relies on the existence of two networks. The first one represents the original network after vulcanization and is sensitive to chain scission. The second network accounts for the formation of additional crosslinking during aging. Besides the use of user subroutines to describe the two-network model, an element overlay technique is also needed as the full set of both material behaviors did not exist for assignment to a single element. This element overlay technique is valuable for research and developmental purposes but makes extension to industrial usage quite challenging. Our goal is to simulate the CS of elastomers after long-term aging in a commercial finite element software with no need for extra subroutine codes or mesh superposition. Ethylene propylene diene (EPDM) O-rings were aged in a compressed state at 75 °C, 100 °C, 125 °C and 150 °C for up to 183 days. Investigations of the experimental test results were used to identify material models and their parameters to develop a finite element model to simulate CS. The model was implemented in the finite element software ABAQUS/Standard® with a sequential temperature-displacement coupling. Regarding the influence of temperature, the Arrhenius equation is adopted for the time-temperature relationship. The activation energy value that is required for the simulation is firstly determined from shifting the experimental CS results with the time-temperature superposition technique and plotting the shift factors in an Arrhenius diagram. The experiments were compared with the simulation results. Afterwards different activation energies were used in the simulation and discussed. A suitable choice of the activation energy value with regard to the reference temperature and the test temperature is presented. With the chosen activation energies, the match between numerical CS values after long-term aging and the experimental results was improved. 2022 Proceedings of the ASME 2022 Pressure Vessels & Piping Conference PVP2022 ASME 2022 Pressure Vessels & Piping Conference Las Vegas, USA 17.07.2022 22.07.2022 1 9 2023-04-24 OPUS4-59769 Beitrag zu einem Sammelband Zaghdoudi, M.; Kömmling, Anja; Jaunich, Matthias; Wolff, Dietmar Altenbach, H.; Hitzler, L.; Johlitz, M.; Merkel, M.; Öchsner, A. Analysis of Heterogeneous Ageing of HNBR O-Rings Abstract Hydrogenated nitrile butadiene rubber (HNBR) elastomer was thermo-oxidatively aged at different temperatures up to 150 °C. Fourier transform infrared spectroscopy (FTIR), compression stress relaxation (CSR) and international rubber hardness degree (IRHD) microhardness were used to characterise the chemo-mechanical changes of HNBR O-rings during thermo-oxidative ageing. FTIR shows the development of carbonyl, methyl and ester groups but the nitrile content was not affected by ageing. The effect of sample geometry during CSR was investigated. CSR data were converted through integrated kinetic laws. The conversion has proven its sensibility to detect heterogeneous ageing. This was confirmed by the IRHD measure-ments across the section of O-rings. The influence of compression during ageing was assessed through IRHD measurements across the section of compressed and uncom-pressed aged O-rings. The DLO effect was more pronounced in compressed O-rings. By applying the model of Wise et al., theoretical IRHD and oxidation profiles were determined on the basis of IRHD experimental data of compressed O-rings. Good agreements between the experimental and the theoretical IRHD profiles in the core region were obtained. However, near the edge, the theoretical IRHD values were overestimated. Cham, Switzerland Springer Nature 2024 Lectures Notes on Advanced Structured Materials 2 978-3-031-49042-2 331 348 10.1007/978-3-031-49043-9 2024-03-27