TY - CONF A1 - Sagradov, Ilja T1 - Long-term tests and numerical simulations on metal seals based on continuous force measurement in compressed state N2 - In Germany, the search for a disposal site for heat-generating radioactive waste will take decades longer than originally assumed. Transport and storage casks must therefore ensure safe containment for extended interim storage periods, possibly over 100 years. In order to maintain the required leak tightness, spring core metal seals with aluminum or silver cladding are used. As sealing force decreases over time, BAM has been conducting tests for over 15 years to prove their long-term reliability. This work - a joint project of BASE and BAM - aims to obtain additional material data using a new device for continuous measurement of compression force over time and temperature for lifetime prediction models and is supported by FEM simulations. Initial tests on aluminum and silver seals have been completed, and first results are presented. T2 - safeND 2025 CY - Berlin, Germany DA - 17.09.2025 KW - Interim storage KW - Metal seal KW - Restoring force PY - 2025 AN - OPUS4-64991 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zaghdoudi, Maha A1 - Weber, Mike A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Simulation of compression set of epdm o-rings during aging N2 - 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. T2 - ASME 2022 Pressure Vessels & Piping Conference CY - Las Vegas, USA DA - 17.07.2022 KW - Simulation KW - Compression set KW - EPDM KW - Aging PY - 2022 SP - 1 EP - 9 AN - OPUS4-57370 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sagradov, Ilja T1 - Long-term tests on metal seals using continuous force measurement in compressed state N2 - In Germany, spent fuel and heat generating radioactive waste is stored in casks for transport and storage (DPCs). The storage licenses were granted for up to 40 years. Due to the delay in identifying a final repository site for such radioactive waste, the storage periods are to be extended significantly. The objective of our research work is to collect additional material data for metal seals in order to be able to better assess the long-term safety of the sealing system of the casks for a period of up to 100 years. A principal safety consideration for the DPCs is the long-term performance of bolted lid sealing systems utilizing metal seals to ensure the safe enclosure of the radioactive inventory during interim storage. To assess the sealing behavior, it is necessary to examine the aging-dependent residual restoring force for the metal seals and the usable resilience. By investigating the change in these values as a function of time and temperature, further insight can be gained into the assessment of long-term safety for extended interim storage. In the present study, the restoring force of metal seals with an outer aluminum jacket and a torus diameter of 9.9 mm was measured continuously. For this purpose, a specially designed device equipped with a load cell was used under isothermal conditions. As part of the investigation, the level and rate of decrease of the restoring seal force were recorded over test periods of one and two months. The seal temperature was set to 35 °C, 75 °C, 100 °C, 125 °C, and 150 °C, respectively. A direct correlation was observed between the temperature of the seal, the level of the restoring force after compressing and heating the seal, and the drop-off characteristics of the restoring force. It was found that in our test device the force level immediately after reaching the respective temperature is lower for higher seal temperatures, while the drop rate of the restoring force is higher. This paper describes the experimental setting and discusses first results in comparison with our long-term discontinuous measurements. T2 - 21st International Symposium on the Packaging and Transportation of Radioactive Materials - PATRAM 2025 CY - San Antonio, TX, USA DA - 27.07.2025 KW - Temperature-Dependent Performance KW - Extended Interim Storage KW - Long-Term Safety Assessment KW - Metal Seal Aging KW - Restoring Force Degradation PY - 2025 AN - OPUS4-63891 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zaghdoudi, Maha T1 - Analysis of heterogeneous ageing of hnbr o rings N2 - 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 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 measurements across the section of O-rings. Oxidation profiles were determined by applying the model of Wise et al. to the IRHD experimental results. T2 - The 2023 Postgraduate Seminar - Advanced Structured Materials CY - Barcelona, Spain DA - 20.02.2023 KW - HNBR KW - Heterogeneous ageing KW - IRHD KW - FTIR KW - CSR PY - 2023 AN - OPUS4-57057 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias T1 - Aging investigations of metal seals used in containers for interim storage of spent fuel N2 - In Germany dual purpose containers with double lid systems are used for the transport and storage of spent fuel and high level radioactive waste. The bolted lids are equipped with metal seals (e.g. Helicoflex®) to ensure the safe enclosure of the inventory for the required time period. The used metal seals have a layered structure consisting of three components. In the center a helical spring is positioned that is surrounded by two C-shaped jackets. The helical spring is mainly responsible for generation of the required restoring force. The inner jacket is made of stainless steel and homogenizes the restoring force generated by the helical spring. The outer jacket is made of silver or aluminum. Both metals are soft in comparison to the contact partners (lid and container body). During bolting of the lid the seal is compressed between lid and container body. The generated restoring force of the helical spring causes a plastic deformation of the outer jacket which adapts to the surfaces of the lid and the container body. Hence, leakage paths are closed and the sealing function is caused. Typical durations for existing interim storage licenses in Germany are 40 years, but due to the challenges in selection and construction of a final repository it can be expected that they have to be extended to longer periods. An extension of license periods requires knowledge of the long-term behavior of the seals. To meet this challenge long-term investigations have been started at Bundesanstalt für Materialforschung und –prüfung (BAM) in 2009. These tests focus on seals assembled in test flanges which are stored at temperatures ranging from room temperature to 150 °C for accelerated aging. The aged seals are tested repeatedly after certain aging steps and the performance is evaluated in respect to the leakage rate, the remaining seal force, and the useable resilience upon decompression. In this contribution an update on the running investigations in respect to earlier publications (Grelle et al. 2019, Goral et al. 2023) will be given and the implications of the results for resilient long-term safety will be presented. New activities will be addressed and their expected outcome be discussed. T2 - PVP2024, Pressure Vessels & Piping Conference CY - Bellevue, WA, USA DA - 29.07.2024 KW - Metal seal KW - Aging KW - Interim storage PY - 2024 AN - OPUS4-61355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias T1 - Low temperature properties of rubber seals N2 - Understanding the failure mechanisms that lead to leakage of rubber seals at low temperatures is important. Rubber properties are highly temperature dependent. Changes in behaviour at low temperatures can result from the rubber-glass transition and for some rubbers by partial crystallisation. Experimental results on the low temperature behaviour of different rubber seals were discussed to help understand seal failure processes. T2 - Rubber in Engineering Group (RIEG) webinar an Elastomers at Low Temperatures CY - Online meeting DA - 11.09.2020 KW - Low temperature KW - Rubber seal KW - Compression set KW - Glass transition PY - 2020 UR - https://www.iom3.org/rubber-engineering-group/event/elastomers-low-temperatures AN - OPUS4-51306 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sagradov, Ilja T1 - Long-term tests on metal seals using continuous force measurement in compressed state N2 - In Germany, spent fuel and heat generating radioactive waste is stored in casks for transport and storage (DPCs). The storage licenses were granted for up to 40 years. Due to the delay in identifying a final repository site for such radioactive waste, the storage periods are to be extended significantly. The objective of our research work is to collect additional material data for metal seals in order to be able to better assess the long-term safety of the sealing system of the casks for a period of up to 100 years. A principal safety consideration for the DPCs is the long-term performance of bolted lid sealing systems utilizing metal seals to ensure the safe enclosure of the radioactive inventory during interim storage. To assess the sealing behavior, it is necessary to examine the aging-dependent residual restoring force for the metal seals and the usable resilience. By investigating the change in these values as a function of time and temperature, further insight can be gained into the assessment of long-term safety for extended interim storage. In the present study, the restoring force of metal seals with an outer aluminum jacket and a torus diameter of 9.9 mm was measured continuously. For this purpose, a specially designed device equipped with a load cell was used under isothermal conditions. As part of the investigation, the level and rate of decrease of the restoring seal force were recorded over test periods of one and two months. The seal temperature was set to 35 °C, 75 °C, 100 °C, 125 °C, and 150 °C, respectively. A direct correlation was observed between the temperature of the seal, the level of the restoring force after compressing and heating the seal, and the drop-off characteristics of the restoring force. It was found that in our test device the force level immediately after reaching the respective temperature is lower for higher seal temperatures, while the drop rate of the restoring force is higher. This paper describes the experimental setting and discusses first results in comparison with our long-term discontinuous measurements. T2 - 21st International Symposium on the Packaging and Transportation of Radioactive Materials - PATRAM 2025 CY - San Antonio, TX, USA DA - 27.07.2025 KW - Long-Term Safety Assessment KW - Extended Interim Storage KW - Metal Seal Aging KW - Restoring Force Degradation KW - Temperature-Dependent Performance PY - 2025 VL - 2025 SP - 1 EP - 10 CY - Indianapolis, IN, USA AN - OPUS4-63881 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vega Puga, E. A1 - Wachtendorf, Volker A1 - Kömmling, Anja A1 - Brendelberger, S. A1 - Jaunich, Matthias A1 - Sattler, C. T1 - Lifetime prediction and degradation assessment of FKM and FFKM O-rings under high temperature thermo-oxidative ageing N2 - To support the development of solar reactor technologies for hydrogen production, this study investigates the thermo-oxidative degradation mechanisms of fluorinated elastomers and predicts their lifetimes at high temperatures (200–300 ◦C) consistent with the application requirements. An accelerated ageing programme is conducted with FKM and FFKM O-rings and flat samples for up to 21 days. Optical microscopy is used to analyse the exposed seals’ morphological changes, while IR microscopy is utilised to investigate the underlying chemical degradation mechanisms of both elastomers. Findings suggest that FKM’s degradation arises from dehydrofluorination of the polymer, followed by chain scission and backbone cleavage as a result of the oxidation of newly formed C=C double bonds. FFKM’s degradation is primarily associated with chain scission, but there is also indication that post-curing processes may occur during material ageing. Furthermore, hardness, equilibrium compression set (CS), continuous compression stress relaxation (CSR) and leakage rate tests are used to evaluate changes in the mechanical properties and sealing performance of the elastomers. Equilibrium CS data is extrapolated using time-temperature shifts (TTS) and used to derive an end-of-life criterion of 75 % equilibrium CS, which correlates to leakage rates higher than a predetermined threshold. Service lifetime predictions of FKM and FFKM O-rings at several temperatures are performed and a seal operating temperature of 200 ◦C is suggested, which ensures reasonable O-ring replacement intervals of more than half a year in the solar reactor for both considered materials. KW - Fluoroelastomer KW - Perfluoroelastomer KW - Thermo-oxidative ageing KW - Lifetime prediction KW - Compression set PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630112 DO - https://doi.org/10.1016/j.polymertesting.2025.108820 SN - 1873-2348 VL - 147 SP - 1 EP - 17 PB - Elsevier BV CY - Amsterdam AN - OPUS4-63011 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liu, Yung A1 - Völzke, Holger A1 - Zencker, Uwe A1 - Jaunich, Matthias T1 - Cooperation in Advanced Technologies Associated with the Back End of Nuclear Fuel Cycle N2 - A Memorandum of Understanding (MOU) between Argonne National Laboratory (Argonne) and the German Bundesanstalt für Materialforschung und -prüfung (BAM) was signed in October 2014. Its objectives are to promote cooperation among scientists and specialists at Argonne and BAM and establish a framework for collaboration in advanced technologies associated with the back end of the nuclear fuel cycle. Collaborative activities involving Argonne and BAM may be implemented through the promotion of joint research activities and scientific workshops and conferences; exchange of technical information; and visits by scientists, specialists, and graduate, postgraduate, and Ph.D. students. The MOU was renewed in January 2020 for another five years. Highlights of the progress and achievements are provided in identified topical areas for collaboration on ageing management guidance, storage, transportation and disposal R&D, joint conference activities, and conclude with the benefits of the MOU in fostering Argonne and BAM collaboration. T2 - 26th International Conference on Structural Mechanics in Reactor Technology - SMiRT 26 CY - Potsdam, Germany DA - 10.07.2022 KW - Nuclear fuel cycle KW - Back end KW - Spent fuel performance KW - Storage KW - Transportation PY - 2022 SP - 1 EP - 10 AN - OPUS4-55861 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias T1 - Ageing under Hydrogen: effects on O-ring seals N2 - In this work we present results for three typical sealing materials (EPDM, HNBR, FKM) after up to 100 days ageing at high temperature under hydrogen. To allow for a better evaluation of the occurring changes the results are compared with effects of ageing in air on the material properties. Despite the common assumption that ageing under hydrogen atmosphere is expected to be less severe for the material in com-parison to air ageing, this is not seen for every material. T2 - Technomer 2023 CY - Chemnitz, Germany DA - 09.11.2023 KW - Hydrogen KW - Ageing KW - Seal KW - Compression set PY - 2023 AN - OPUS4-58818 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias T1 - Investigations of Aged Metal Seals for Interim Storage N2 - The storage of spent fuel and high level radioactive waste in Germany is performed in interim storage containers with double lid systems. The lids are bolted and equipped with metal seals (e.g. Helicoflex®) to ensure the safe enclosure of the inventory. The used metal seals have a layered structure consisting of three components as can be seen schematically in the cross-sectional view in Fig. 1. In the center a helical spring is positioned that is surrounded by two C-shaped jackets and is mainly responsible for generation of the required restoring force. The inner jacket is made of stainless steel and homogenizes the restoring force of the helical spring. The outer jacket is made of silver or aluminium which both are soft metals in comparison to the contact partners (lid and container body). During bolting of the lid to the container body the seal is compressed. The generated restoring force of the helical spring causes a plastic deformation of the outer jacket and adapts to the surfaces of the lid and the container body. Hence, leakage paths are closed and the sealing function is generated. Typical durations for existing interim storage licenses in Germany are 40 years, but it can be expected that they have to be extended to longer periods as a final repository will not be available before the end of the running licence periods. This extension of license periods requires a solid understanding of the long-term behaviour of the seals under storage conditions. To meet this challenge long-term investigations have been started at Bundesanstalt für Materialforschung und –prüfung (BAM) in 2009. These tests focus on seals assembled in test flanges which are stored at temperatures ranging from room temperature to 150 °C for accelerated ageing. The aged seals are tested repeatedly after certain ageing steps and the leakage rate as indicator for sealing performance, the remaining seal force, and the useable resilience upon decompression are determined. In the poster an update on the performed investigations in respect to earlier publications (Grelle et al. 2019, Goral et al. 2023) will be given and the implications of the results for resilient long term safety will be presented. Additionally, a focus will be laid on the currently planned further investigations and the question “What is additionally needed for evaluation of an interim storage period extension in regard to the used metal seals?” will be addressed. T2 - safeND2023: Forschungssymposium des BASE CY - Berlin, Germany DA - 13.09.2023 KW - Metal seal KW - Interim storage KW - Ageing PY - 2023 AN - OPUS4-58568 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias T1 - Comparison of Ageing Behavior of O-Ring Seals Under Hydrogen and Air N2 - Elastomeric seals are essential components in the infrastructure which prevent leakage of gas and ensure proper function of technical devices and are therefore highly safety relevant. For proper function a remaining resilience and tolerance to pressure changes is required. The ageing of 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. automotive, piping or container applications, a long lifetime or at least a timely exchange of a seal before occurrence of critical failure is desired. Hydrogen is a key element for the energy turnaround and therefore the compatibility of seals with hydrogen is essential. In addition to the effect of hydrogen uptake and release, which might also cause destructive effects such as rapid gas decompression, ageing at high temperature under hydrogen atmosphere is of interest too. Most of the existing work is addressing the performance of new materials and comprises only very limited investigations concerning long-term use and the behaviour of aged materials in contact with hydrogen. As ageing can lead to substantial changes of material properties, it must be evaluated whether these changes are beneficial or deteriorating for the component function. In this work we present and compare results of the characterization of three sealing materials (EPDM, HNBR, FKM) after ageing at high temperature under hydrogen and air. Despite the common assumption that ageing under hydrogen atmosphere should be less severe for the material in comparison to air ageing, this is not the case for every material. T2 - ASME PVP2025, Pressure Vessels & Piping Conference CY - Montreal, Canada DA - 20.07.2025 KW - Aging KW - Seal KW - Compression set KW - Atomic force microscopy PY - 2025 AN - OPUS4-63888 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias T1 - Elastomerdichtungen für Wasserstoffanwendungen - Vergleich des Alterungsverhaltens in Luft und Wasserstoff N2 - In diesem Beitrag soll ein Fokus auf das Alterungsverhalten von Elastomerdichtungen unter Wasserstoff gelegt werden. Hierfür wurden Untersuchungen bei einem mittleren Wasserstoffdruck über Alterungszeiten von bis zu 100 Tagen durchgeführt. Das Alterungsverhalten wird im Vergleich der Alterungseffekte unter thermooxidativen Bedingungen betrachtet und bewertet. Die Annahme, dass der Alterungseffekt unter Wasserstoff stets weniger ausgeprägt ist als an Luft bestätigt sich nicht durch die Ergebnisse. T2 - 4. O-Ring-Forum der Firma ISGATEC CY - Bad Schönborn, Germany DA - 15.05.2025 KW - Wasserstoff KW - Dichtung KW - Thermische Alterung KW - Elastomer PY - 2025 AN - OPUS4-63135 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Ammerman, D. J. A1 - Bignell, J. L. A1 - Bjorkman, G. S. A1 - Breach, M. R. A1 - Broz, V. A. A1 - Jordan, J. A1 - Kuehner, S. A1 - Molitoris, D. P. A1 - Reinhardt, W. A1 - Rigato, A. B. A1 - Rosvall, E. S. A1 - Sakalaukus Jr., P. J. A1 - Shih, P. Y.-K. A1 - Siromani, D. A1 - Snow, S. D. A1 - Tso, C.-F. A1 - Yaksh, M. C. A1 - Zencker, Uwe A1 - Zhang, X. T1 - Guidance document - Use of explicit finite element analysis for the evaluation of radioactive material transport packages and storge casks in energy-limited impact events N2 - The purpose of this document is to provide guidance for developing quality finite element models to ensure, with reasonable certainty, that the model produces accurate results for comparison with the strain-based or stress-based acceptance criteria of Section III, Division 3 of the ASME Boiler and Pressure Vessel Code, but could be applicable to other Sections of the Code or other codes. Models developed following the guidance provided in this document meet the definition of a "Quality Model," as described in Paragraph EE 1240 of the Nonmandatory Appendix EE (Strain-Based Acceptance Criteria Definitions and Background Information). It cannot be emphasized enough, however, that the guidance supplied here does not constitute requirements. Rather, the intent of the guidance is to give practical direction to analysts (i.e., this is not a set of regulatory requirements). This guidance document is an "evolving" document. It will undergo revision as computing capability and FEA techniques progress, and as example problems are developed. KW - Computational modeling KW - Explicit dynamics PY - 2025 SN - 978-0-7918-7749-4 VL - NTB-6 SP - 1 EP - 153 PB - Americal Society of Mechanical Engineers (ASME) CY - New York, NY ET - 2025 AN - OPUS4-65759 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -