TY - CONF A1 - Wolff, Dietmar A1 - von der Ehe, Kerstin A1 - Jaunich, Matthias A1 - Böhning, Martin T1 - Performance of neutron radiation shielding material (U)HMW-PE influenced by gamma radiation N2 - Due to their extreme high hydrogen contents high molecular weight (HMW-) and ultra-high molecular weight (UHMW-) polyethylene (PE) are a comprehensible choice as neutron radiation shielding material in thick walled metallic casks for storage and transport of radioactive materials. For this application it has to be taken into consideration that gamma radiation – that is a direct consequence of inserting radioactive material in such casks – has a high influence on the molecular structure of polyethylene. In order to be applicable for long-term neutron radiation shielding purposes during the whole storage period (in Germany for instance up to 40 years) PE has to withstand any type of degradation affecting safety relevant aspects. The scope of our work comprises an estimation of the influence of gamma radiation and temperature on the molecular and supra molecular structure of (U)HMW-PE used as cask components for neutron radiation shielding. Therefore it was investigated to what extent these changes are detectable by a combination of conventional polymer characterization techniques such as Differential Scanning Calorimetry (DSC), Thermo Mechanical Analysis (TMA), Dynamic Mechanical Analysis (DMA), and Thermo Gravimetric Analysis (TGA). Additionally optical (FTIR) and weighing methods were applied. For UHMWPE the results are compared with those published for similar UHMW-PE material that is used in medical technology. For this application, gamma irradiation is applied deliberately for purposes such as sterilization and crosslinking, the latter leading to partial improvement of mechanical properties and better chemical stability. As a result the so far observed structural changes of the irradiated material are not safety relevant for the application of polyethylene as neutron shielding material; moreover, some properties actually improve via irradiation. T2 - PSAM 11 ESREL 2012 - 11th International probabilistic safety assessment and management conference & The annual european safety and reliability conference CY - Helsinki, Finland DA - 25.06.2012 KW - (U)HMW-PE KW - Gamma irradiation KW - Shielding material KW - Cask for storage and transport of radioactive materials PY - 2012 SP - 1 EP - 8 AN - OPUS4-26176 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Wolff, Dietmar A1 - von der Ehe, Kerstin A1 - Jaunich, Matthias A1 - Böhning, Martin A1 - Goering, Harald ED - Yamamoto, T. T1 - (U)HMWPE as neutron radiation shielding materials: impact of gamma radiation on structure and properties N2 - Due to their extreme high hydrogen contents, high molecular weight (HMW-) and ultra-high molecular weight (UHMW-) polyethylene (PE) are a comprehensible choice as neutron radiation shielding material in casks for storage and transport of radioactive materials. But as a direct consequence of inserting radioactive material in such casks, gamma radiation occurs. Hence, the impact of gamma radiation on the molecular structure of polyethylene has to be taken into consideration. Consequently, PE has to withstand any type of gamma radiation induced degradation affecting safety relevant aspects in order to be applicable for long term neutron radiation shielding purposes during the whole storage period (in Germany, for instance, up to 40 years). The scope of our investigation comprises an estimation of the impact of gamma radiation and temperature on the molecular and supra molecular structure of the two types of PE used as neutron radiation shielding cask components. A further point which is worth exploring is to what extent these changes are detectable by conventional analysis methods. Therefore, thermoanalytical measurements were performed such as differential scanning calorimetry (DSC), thermo mechanical analysis (TMA), dynamic mechanical analysis (DMA), and thermo gravimetric analysis (TGA). Additionally optical and weighing methods were applied. With those methods it is possible to detect structural changes in polyethylene induced by exposure to gamma radiation. The observed amounts of changes of the irradiated material are not safety relevant for the application of polyethylene as neutron radiation shielding material; moreover, some properties actually improve via irradiation. KW - HMW-PE KW - UHMW-PE KW - Gamma irradiation KW - Neutron radiation shielding material PY - 2013 SN - 978-0-8031-7533-4 DO - https://doi.org/10.1520/STP103980 N1 - Serientitel: STP – Series title: STP VL - 25 IS - STP 1547 SP - 211 EP - 227 AN - OPUS4-27931 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -