TY - CONF A1 - Weber, Mike A1 - Zaghdoudi, Maha A1 - Brandt, Guido A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Coefficients of Friction in Dependence on Aging State of Elastomers – Experimental Identification and Numerical Simulation of the Experiment N2 - 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. T2 - ASME 2022 Pressure Vessels & Piping Conference (PVP2022) CY - Las Vegas, NV, USA DA - 17.02.2022 KW - Numerical Simulation KW - Radioactive Waste KW - Elastomers KW - Aging KW - Seal Behavior KW - Leakage Rate KW - Coefficient of Friction KW - Experiment PY - 2022 SP - 1 EP - 8 PB - American Society of Mechanical Engineers (ASME) CY - New York, NY, USA AN - OPUS4-57093 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Silbernagl, Dorothee A1 - Kömmling, Anja A1 - Zaghdoudi, Maha A1 - Ghasem Zadeh Khorasani, Media A1 - Jaunich, Matthias T1 - Data-driven nanomechanical study of filled fluoroelastomer aged in air and hydrogen atmosphere N2 - Fluoroelastomer (FKM) composites are typically used as sealing materials in challenging non-ambient environments. Depending on the environment, two main aging mechanisms, chemical aging, and physical aging, can be identified. Chemical aging, the degradation of the elastomer, is present for example in thermal-oxidative conditions and can be directly observed as it affects the bulk. Physical aging, relaxation and rearrangement of the elastomers segmental conformation is commonly observed at elevated temperatures and effects predominantly the elastomer interphase. As a highly localized nanoscopic effect it is usually observed indirectly by phenomological approaches and not systematically understood. In this study, as a typical example for chemical aging, filled FKM was aged in air (150°C, 100 days). Physical aging of FKM was realized by exposure to chemically inert H2 (150°C, 50 bar, 100 days), since temperature and gas-induced swelling is known to promote physical aging. The effects of both conditions are directly compared with the initial unaged material. We use atomic force microscopy (AFM) force spectroscopy as a method to resolve nanoscopic heterogeneous FKM. With this method the effect of aging on the spatially distinguishable material phases was directly observed. In thermal oxidative aged FKM the matrix shows a decrease in van der Waals interactions and stiffness, indicating dehydrofluorination and chain scission. In H2 aged FKM, the development of an immobilized amorphous interphase (IAP) was observed, indicating physical aging. By additionally evaluating a larger data set with supervised machine learning, these observations were validated for a larger, statistically representative sample area, allowing conclusions to be drawn about the macroscopic behaviour of the material. KW - Fluoroelastomer KW - Atomic force microscopy KW - Data-driven KW - Hydrogen KW - Ageing mechanism KW - Physical aging KW - Polymer interphase PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-648154 DO - https://doi.org/10.1016/j.polymdegradstab.2025.111715 SN - 0141-3910 VL - 242 SP - 1 EP - 10 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-64815 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias T1 - An update on metal seal tests performed at BAM and implications for interim storage N2 - 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. Metallic seals are in use in interim storage casks for used fuel and high active waste. Their change in performance over time is of high importance for maintaining 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. In this contribution an update on the performed tests and their respective results will be given in respect to the overview presented in 2020. The understanding of the long-term behaviour of the sealing systems and the performance evaluation during interim storage and subsequent transportation are our goals. T2 - SEDS-Workshop: Sicherheit der längerfristigen trockenen Zwischenlagerung CY - Garching, Germany DA - 15.05.2024 KW - Metal seals KW - Ageing KW - Leakage rate KW - Creep PY - 2024 AN - OPUS4-60640 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zaghdoudi, Maha A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar A1 - Albouy, P.-A. A1 - Häcker, Ralf A1 - Stock, Daniel T1 - Overview of ongoing research and future prospects on polyethylene neutron shielding materials at bam N2 - 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. T2 - PATRAM22 CY - Juan-Les-Pins, Antibes, France DA - 11.06.2023 KW - (U)HMWPE KW - Ageing KW - Irradiation KW - WAXD KW - SHPB PY - 2023 SP - 1 EP - 10 AN - OPUS4-57707 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Goral, Milan A1 - Sagradov, Ilja A1 - Wolff, Dietmar A1 - Völzke, Holger T1 - Aging investigations of metal seals used in containers for interim storage of spent fuel N2 - For bolted casks for used fuel and high level waste the sealing system has an important impact of ensuring safe enclosure of the inventory The used metal seals show some changes over time which have been addressed for nearly 15 years in running experiments at BAM The observed changes are temperature de pendent and therefore it is expected that test s at higher temperature allow for an acceleration of the effects and ideally the proposal of an ageing model covering the expected time of use . Nevertheless, questions concerning the influence of the experimental approach on the results and effects taking place at the initial days of ageing remain. To address these a new project was launched to give a better understanding of the seal behavior. T2 - PVP2024, Pressure Vessels & Piping Conference CY - Bellevue, WA, USA DA - 29.07.2024 KW - Metal seal KW - Aging KW - Interim storage PY - 2024 SN - 978-0-7918-8851-3 SP - 1 EP - 4 PB - ASME AN - OPUS4-61357 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias T1 - Tests of metallic seals at Bam 3.4 performed over more than 15 years N2 - 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) in Germany. The time dependant behaviour of metallic seals, which are employed in interim storage casks for used fuel and high active waste, 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. In this contribution an overview of the performed tests and their respective results will be given. T2 - 5th sealing workshop by Maestral CY - Avignon, France DA - 05.11.2024 KW - Metal seal KW - Aging KW - Interim storage PY - 2024 AN - OPUS4-62048 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Goral, Milan A1 - Wolff, Dietmar T1 - Insights for lifetime predictions of O-ring seals from five-year long-term aging tests N2 - 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. KW - HNBR KW - EPDM KW - FKM KW - DLO KW - Hardness KW - Compression set KW - Rubber KW - Elastomer KW - Degradation PY - 2020 DO - https://doi.org/10.1016/j.polymdegradstab.2020.109278 VL - 179 SP - 109278 PB - Elsevier Ltd. AN - OPUS4-51060 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zaghdoudi, Maha A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Erroneous or Arrhenius: A Degradation Rate-Based Model for EPDM during Homogeneous Ageing N2 - 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. KW - Kinetic study KW - Arrhenius KW - TTS KW - Modeling KW - Chemical processes KW - Stress relaxation PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-512931 DO - https://doi.org/10.3390/polym12092152 SN - 2073-4360 VL - 12 IS - 9 SP - 1 EP - 21 AN - OPUS4-51293 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weber, Mike A1 - Jaunich, Matthias A1 - Goral, Milan A1 - Völzke, Holger T1 - Reproducing and discussion of mechanisms in the contact area between metallic seals and flange during aging by finite element analysis (FEA) N2 - When the first site-specific interim storage licenses for DPCs (dual purpose casks), loaded with spent nuclear fuel or vitrified high-level waste from reprocessing were issued, a duration of 40 years was considered for interim storage license application and the long-term safety assessment of casks. In the meantime, the availability of a final repository is further delayed by several decades and thus interim storage for more than a century becomes a necessity. To assess the long-term performance of the typically used metal seals (e.g. Helicoflex), consisting of a helical spring (Nimonic), an inner stainless steel liner and an outer liner made from silver or aluminum, several experimental programs were conducted and are still ongoing. The investigated metal seals are typically mounted in mock-up flange systems and stored at increased temperatures to accelerate the aging process. In certain intervals the remaining seal force, the useable resilience and the corresponding leakage rate are determined. BAM has accompanied such programs for many years and started independent investigations in 2009. Although the remaining seal force is often used as “…one of the key parameters regarding sealing performances over time…” the presented results so far have shown that the courses of the leakage rate and the remaining seal force do not always correlate as expected. In 2016 BAM firstly published results of seals with aluminum liners where the measured leakage rate started to rise after a quite short time period (< 1 year) at 150 °C, although the seal force decreased only slightly compared to the previous measurement. After exceeding the required leakage rate of 10-8 Pa*m3/s it decreased again to acceptable values in the further course of aging. With reference to already published works, BAM has developed a new detailed ABAQUS finite-element (FE) model to represent the behavior of the seal mounted in the mock-up flange during aging, mainly characterized by the creeping of the outer liner. The main goal of the numerical simulation is to reproduce and understand the changing distribution of contact stresses (outer liner/flange) during aging and to discuss if and how it could be causative for the observed early breach of the leak tightness criteria and its later recovery. T2 - PATRAM 2025, 21st International Symposium on the Packaging and Transportation of Radioactive Materials CY - San Antonio, Texas, USA DA - 27.07.2025 KW - Finite element analysis KW - Metallic seals KW - Aging KW - Contact area PY - 2025 SP - 1 EP - 10 PB - INMM CY - Indianopolis, Indiana, USA AN - OPUS4-63882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Kömmling, Anja A1 - Böhning, Martin A1 - Silbernagl, Dorothee 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, Quebec, Canada DA - 20.07.2025 KW - Aging KW - Seal KW - Compression set KW - Atomic force microscopy PY - 2025 SP - 1 EP - 7 AN - OPUS4-63889 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias T1 - Comparison of ageing behaviour of O-ring seals under hydrogen and air N2 - Elastomeric seals are essential components in the infrastructure which prevent leakage of gas and 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 characterisation 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 - RubberCon 2023 CY - Edinburgh, Scotland DA - 09.05.2023 KW - Hydrogen KW - Ageing KW - Seal PY - 2023 AN - OPUS4-58178 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias T1 - Investigations at BAM on Fuel Cladding Integrity and DPC Seal Performance N2 - The presentation provides an update on preliminary results from research projects in the area of long term performance of metal seals and fuel rod integrity as safety relevant components of spent fuel transport and storage casks for spent nuclear fuel. T2 - Extended Storage Collaboration Program (ESCP) winter meeting 2022 CY - Charlotte, NC, USA DA - 07.11.2022 KW - Metal seal KW - Fuel cladding KW - Ring compression test KW - Brittle failure PY - 2022 AN - OPUS4-56400 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zaghdoudi, M. A1 - Kömmling, Anja A1 - Böhning, Martin A1 - Jaunich, Matthias T1 - Ageing of elastomers in air and in hydrogen environment - A comparative study N2 - EPDM, HNBR and FKM materials were exposed at 150 ◦C to air under atmospheric pressure and to hydrogen at 50 bar for different ageing times. All measurements after hydrogen exposure were conducted on samples in degassed condition to assess irreversible effects resulting from that exposure and to compare them to those after ageing in air. Density, hardness, tensile properties, compression set, and hydrogen permeability of all samples were analysed. In both ageing environments, HNBR exhibited the most significant changes of material properties. However, for both EPDM and HNBR, considerably less severe ageing effects were observed under hydrogen in comparison to ageing in air. On the other hand, FKM showed about the same low level of deterioration in both ageing environments but exhibited poor resistance against damage due to rapid gas decompression in hydrogen environment that can lead to seal failure. The obtained results may serve as a guidance toward a better understanding for design and utilisation of elastomeric materials in future hydrogen infrastructure components. KW - Rapid gas decompression KW - Condensed matter physics KW - Hydrogen KW - Sustainability and the environment KW - Rubber sealing KW - Renewable energy PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597417 DO - https://doi.org/10.1016/j.ijhydene.2024.03.053 SN - 0360-3199 SN - 1879-3487 VL - 63 SP - 207 EP - 216 PB - Elsevier CY - Oxford AN - OPUS4-59741 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 - Numerical Modelling of Compression Stress Relaxation and Compression Set of Elastomer O-Ring During Aging N2 - 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. T2 - ASME 2020 Pressure Vessels & Piping Conference (PVP2020) CY - Online meeting DA - 03.08.2020 KW - Compression Set KW - O-ring KW - Simulation KW - Sequential analysis KW - Ageing KW - stress relaxation PY - 2020 SN - 978-0-7918-8388-4 DO - https://doi.org/10.1115/PVP2020-21270 SP - PVP2020-21270 PB - ASME AN - OPUS4-51490 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Zaghdoudi, M. A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar ED - Altenbach, H. ED - Hitzler, L. ED - Johlitz, M. ED - Merkel, M. ED - Öchsner, A. T1 - Analysis of Heterogeneous Ageing of HNBR O-Rings N2 - 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. KW - Ageing KW - Rubber seals KW - Stress relaxation KW - Modelling PY - 2024 SN - 978-3-031-49042-2 DO - https://doi.org/10.1007/978-3-031-49043-9 SN - 1869-8433 SP - 331 EP - 348 PB - Springer Nature CY - Cham, Switzerland AN - OPUS4-59769 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zaghdoudi, Maha A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Understanding the recovery behaviour and the degradative processes of EPDM during ageing N2 - 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. KW - Compression set KW - Ageing KW - Recovery KW - Degradative processes KW - Leakage rate PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-573699 DO - https://doi.org/10.1016/j.polymertesting.2023.107987 SN - 0142-9418 VL - 121 SP - 107987 PB - Elsevier Ltd. AN - OPUS4-57369 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zaghdoudi, Maha A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Oxidative ageing of elastomers: Experiment and modelling N2 - 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. KW - Compression stress relaxation KW - Compression set KW - IRHD microhardness KW - Modelling PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545910 DO - https://doi.org/10.1007/s00161-022-01093-9 SN - 1432-0959 SP - 1 EP - 9 PB - Springer CY - Berlin AN - OPUS4-54591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jaunich, Matthias A1 - Goral, Milan A1 - Wolff, Dietmar A1 - Völzke, Holger ED - Krüssenberg, A. T1 - Overview of metal seal tests performed at BAM and implications for extended interim storage N2 - 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. T2 - Safety of Extended Dry Storage of Spent Nuclear Fuel SEDS2020: International online-workshop CY - Online meeting DA - 03.06.2020 KW - Metal seal KW - Seal performance KW - Long-term investigation KW - Ageing PY - 2020 DO - https://doi.org/10.3139/124.200071 SN - 0932-3902 VL - 85 IS - 6 SP - 440 EP - 443 PB - Carl Hanser Verlag CY - München AN - OPUS4-51833 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zaghdoudi, M. A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Oxidative ageing of elastomers: experiment and modelling N2 - 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. KW - Compression Set KW - Compression stress relaxation KW - Modelling KW - Ageing KW - Microhardness PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-609332 DO - https://doi.org/10.1007/s00161-022-01093-9 VL - 36 SP - 289 EP - 297 PB - Springer Nature AN - OPUS4-60933 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias T1 - Overview of metal seal tests performed at BAM and implications for extended interim storage N2 - 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. The behaviour of metallic seals, which are employed in interim storage casks for used 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. In this contribution an overview of the performed tests and their respective results will be given. A focus will lie on a comparison between seals with large torus diameter in comparison to small diameters. 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. T2 - 4th Workshop on Safety of Extended Dry Storage of Spent Nuclear Fuel CY - Online meeting DA - 03.06.2020 KW - Seal performance KW - Metal seal KW - Leakage rate PY - 2020 AN - OPUS4-50843 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zaghdoudi, Maha A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Overview of ongoing long-term ageing investigations on elastomer seals N2 - 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. KW - Seal KW - O-Ring KW - Ageing KW - Component tests PY - 2020 SN - 1863-7116 VL - 15 IS - 3 SP - 146 EP - 151 PB - Gupta CY - Ratingen AN - OPUS4-51161 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weber, Mike A1 - Zaghdoudi, Maha A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - A numerical approach to correlate compression stress relaxation and compression set of elastomer O-rings with tightness N2 - 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. T2 - ASME 2021 Pressure Vessels & Piping Conference (PVP2021) CY - Online meeting DA - 13.07.2021 KW - Elastomer KW - Tightness KW - Leakage KW - Compression set KW - Compression stress relaxation PY - 2021 SN - 978-0-7918-8535-2 DO - https://doi.org/10.1115/PVP2021-61976 SP - 1 EP - 8 PB - American Society of Mechanical Engineers (ASME) CY - New York, NY, USA AN - OPUS4-54422 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kömmling, Anja A1 - Grelle, Tobias A1 - Jaunich, Matthias A1 - Goral, Milan A1 - Wolff, Dietmar T1 - Three-dimensional thermal expansion of neat and irradiated (U)HMWPE materials at elevated temperatures N2 - 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. KW - Lupolen KW - Ultra high molecular weight polyethylene KW - GUR KW - Coefficient of thermal expansion KW - High temperature PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563987 DO - https://doi.org/10.1016/j.polymertesting.2022.107841 SN - 0142-9418 VL - 117 SP - 1 EP - 8 PB - Elsevier Ltd. AN - OPUS4-56398 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias T1 - Elastomer seals - overview and development N2 - The talk summarizes the current and future investigations of elastomer seal materials in division 3.4. T2 - IRSN-BAM Symposium Safety of Transport and Storage Packages CY - Online meeting DA - 19.11.2020 KW - Seal KW - Degradation KW - Ageing PY - 2020 AN - OPUS4-51751 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 - 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 - 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 -