TY - JOUR A1 - Kömmling, Anja A1 - von der Ehe, Kerstin A1 - Wolff, Dietmar A1 - Jaunich, Matthias T1 - Effect of high-dose gamma irradiation on (U)HMWPE neutron shielding materials JF - Radiation Physics and Chemistry N2 - 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. KW - Ultra high molecular weight KW - Polyethylene KW - Gamma irradiation KW - Crosslinking KW - Oxidation PY - 2018 DO - https://doi.org/10.1016/j.radphyschem.2017.02.014 SN - 0969-806X VL - 142 SP - 29 EP - 33 PB - Elsevier AN - OPUS4-42941 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Kömmling, Anja A1 - Wolff, Dietmar A1 - Jaunich, Matthias ED - van Breugel, K. ED - Koleva, D. ED - Beek, T. T1 - Investigation of long-term behaviour of elastomeric seals for transport and storage packages T2 - The Aging of Materials and Structures - Towards Scientific Solutions for the Ageing of Our Assets N2 - 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. KW - O Ring KW - Ageing KW - Rubber seal PY - 2018 SN - 978-3-319-70192-9 DO - https://doi.org/10.1007/978-3-319-70194-3_2 SP - 17 EP - 25 PB - Springer AN - OPUS4-43248 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Kömmling, Anja A1 - Horn, Jutta A1 - Völzke, Holger A1 - Wolff, Dietmar T1 - Long-Term Performance of Elastomer seals - From Aging Tests to Lifetime Estimations T2 - Proceedings of the ASME 2018 Pressure Vessels an Piping Conference N2 - 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. T2 - ASME 2018 Pressure Vessels and Piping Conference CY - Prague, Czech Republic DA - 15.07.2018 KW - Seal performance KW - Rubber KW - Ageing PY - 2018 VL - PVP2018 SP - 84631-1 EP - 84631-8 AN - OPUS4-46346 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -