Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-26176 Beitrag zu einem Tagungsband Wolff, Dietmar; von der Ehe, Kerstin; Jaunich, Matthias; Böhning, Martin Performance of neutron radiation shielding material (U)HMW-PE influenced by gamma radiation 2012 PSAM 11 ESREL 2012 - 11th International probabilistic safety assessment and management conference & The annual european safety and reliability conference (Proceedings) PSAM 11 ESREL 2012 - 11th International probabilistic safety assessment and management conference & The annual european safety and reliability conference Helsinki, Finland 2012-06-25 2012-06-29 1 8(?) 2016-02-19 OPUS4-27931 Beitrag zu einem Sammelband Wolff, Dietmar; von der Ehe, Kerstin; Jaunich, Matthias; Böhning, Martin; Goering, Harald Yamamoto, T. (U)HMWPE as neutron radiation shielding materials: impact of gamma radiation on structure and properties Due to their extreme high hydrogen contents, high molecular weight (HMW-) and ultra-high molecular weight (UHMW-) polyethylene (PE) are a comprehensible choice as neutron radiation shielding material in casks for storage and transport of radioactive materials. But as a direct consequence of inserting radioactive material in such casks, gamma radiation occurs. Hence, the impact of gamma radiation on the molecular structure of polyethylene has to be taken into consideration. Consequently, PE has to withstand any type of gamma radiation induced degradation affecting safety relevant aspects in order to be applicable for long term neutron radiation shielding purposes during the whole storage period (in Germany, for instance, up to 40 years). The scope of our investigation comprises an estimation of the impact of gamma radiation and temperature on the molecular and supra molecular structure of the two types of PE used as neutron radiation shielding cask components. A further point which is worth exploring is to what extent these changes are detectable by conventional analysis methods. Therefore, thermoanalytical measurements were performed such as differential scanning calorimetry (DSC), thermo mechanical analysis (TMA), dynamic mechanical analysis (DMA), and thermo gravimetric analysis (TGA). Additionally optical and weighing methods were applied. With those methods it is possible to detect structural changes in polyethylene induced by exposure to gamma radiation. The observed amounts of changes of the irradiated material are not safety relevant for the application of polyethylene as neutron radiation shielding material; moreover, some properties actually improve via irradiation. ASTM International (American Society for Testing and Materials) 2013 Effects of radiation on nuclear materials 25 978-0-8031-7533-4 STP 1547 211 227 10.1520/STP103980 2016-02-20 OPUS4-24620 Beitrag zu einem Tagungsband von der Ehe, Kerstin; Jaunich, Matthias; Wolff, Dietmar UHMW-PE - a shielding material with special properties influenced by radiation Ultra high molecular weight polyethylene (UHMW-PE) - due to its high hydrogen content - is used as neutron shielding material in casks for storage and transport of radioactive materials. Besides this, UHMW-PE - as a high-performance polymer - has been used for several years in medical technology due to its excellent slip and wear properties. Due to the special properties of UHMW-PE which result basically from its extreme chain lengths and its high degree of crystallinity, it is predestinated for the aforementioned applications. In both cases, irradiation and its impact on the molecular structure of polyethylene play an important role. In the first case, irradiation exists as a by-product of inserting the radioactive material in the cask. Hence PE has to withstand any type of degradation affecting safety relevant aspects to be applicable for long term radiation shielding purposes for instance over a period of 40 years. In the second case irradiation is applied deliberately for purposes such as sterilization and crosslinking, leading to partial improvement of the mechanical properties (e.g. fracture toughness, crack propagation resistance, wear resistance) and better Chemical stability. Specifically concerning their use in the field of medical technology, different types of UHMW-PE have been objects of numerous publications. It is generally accepted that two parallel and competitive processes, based on chain scission and reactions of Ccentered radicals and molecular fragments, occur in PE as a consequence of radiation: radical recombination accounts for crosslinking, together with some disproportionation, formation of low molecular weight fragments, and recrystallization. Furthermore, formation of oxygenated structures in the presence of traces of oxygen is an antagonist of the C-centered radicals. Radiation induced scission preferentially takes place in the amorphous phase and noncrystalline surface of the crystals. It is followed by folding of molecular fragments, crystallinity growth and increased perfection in the crystal lamellae [4, 5]. Chain scission results in shorter polymer molecules, fewer entanglements, and consequently, increased molecular mobility. The scope of our investigation comprises an estimation of the radiation and thermal impact on the molecular and supra molecular structure of the two types of PE used for neutron shielding cask components. A further point which is worth to explore is to what extent these changes are detectable by thermo-analytical (TA) methods, such as Differential Scanning Calorimetry (DSC), Thermo Mechanical Analysis (TMA), Dynamic Mechanical Analysis (DMA) and Thermogravimetry (TG). Additionally FT-IR and solubility measurements have been performed. In our studies we focused on the UHMW-PE material GUR 4120 which was y irradiated at RT and compared to the untreated material. Deutsches Atomforum e.V. / Kerntechnische Gesellschaft e.V. 2011 Jahrestagung Kerntechnik 2011 (Proceedings) Jahrestagung Kerntechnik 2011 Berlin, Germany 17.05.2011 19.05.2011 1 5 2016-02-19 OPUS4-24621 Beitrag zu einem Tagungsband von der Ehe, Kerstin; Jaunich, Matthias; Wolff, Dietmar; Böhning, Martin; Goering, Harald Radiation induced structural changes of (U)HMW polyethylene with regard to its application for radiation shielding The special properties of high molecular weight polyethylene (HMW-PE) and ultra high molecular weight polyethylene (UHMW-PE) result basically from their extreme chain lengths and their high degree of crystallinity. As high-performance polymers, they are used for a variety of applications. UHMW-PE in particular is often utilized for endoprothesis (due to its excellent slip and wear properties) and due to its high hydrogen content as a neutron moderator in casks for storage and transport of radioactive materials. To prepare the material for instance for its use as a total joint replacement, it is exposed to radiation for several reasons, such as sterilization and crosslinking, leading to partial improvement of the mechanical properties (e.g. fracture toughness, crack propagation resistance, wear resistance) and better chemical stability. To be applicable for long term radiation shielding purposes for instance over a period of 40 years, PE has to withstand any type of degradation affecting safety relevant aspects. The scope of our investigation comprises an estimation of the radiation impact on the molecular and supra molecular structure of two types of PE and to what extent these changes are detectable by thermo-analytical (TA) methods, such as Differential Scanning Calorimetry (DSC), Thermo Mechanical Analysis (TMA), Dynamic Mechanical Analysis (DMA) and Thermo Gravimetric Analysis (TGA). Additionally FT-IR spectroscopy as well as density and gas sorption measurements were carried out. Due to the poor solubility of HMW-PE and UHMW-PE, some classical analytical techniques are not applicable. But TA-methods represent a feasible approach to detect structural and morphological features of these materials as well as changes caused by external influences, such as thermal treatment and/or irradiation. With the combination of the applied TA-techniques it is possible to distinguish between crosslinking and degradation. PATRAM 2010 PATRAM 2010 - 16th International symposium on the packaging and transport of radioactive materials (Proceedings) PATRAM 2010 - 16th International symposium on the packaging and transport of radioactive materials London, UK 2010-10-03 2010-10-08 1 8 (T25/Paper 173) 2016-02-19 OPUS4-31331 Beitrag zu einem Tagungsband Beckmann, Jörg; von der Ehe, Kerstin; Jaunich, Matthias; Schade, U.; Aziz, E. F.; Wolff, Dietmar Fourier-spektroskopische Untersuchungen im mittleren- und fernen Infrarotbereich an Co-60 bestrahlten und thermisch belasteten ultrahochmolekularen Polyethylen-Proben Fourier-Spektroskopische Untersuchungen von hochmolekularem Polyethylen (HMW-PE) und ultrahochmolekularem Polyethylen (UHMW-PE) im Mittleren - und Fernen Infrarotbereich können Veränderungen der molekularen Strukturen nachweisen, die durch Co60 γ-Strahlung und Rekristallisationsprozesse initiiert werden. UHMW-PE und HMW-PE sind im gewählten IR-Bereich unterscheidbar. Die integrale Absorption der B1u - Gitterschwingungen im Fernen Infrarotbereich (THz-Bereich) ermöglichen die quantitative Beschreibung des Kristallinitätsgrades und dessen Abbau. Die Bildung ungesättigter Vinylengruppen und der Abbau ungesättigter Methylengruppen können im Mittleren Infrarotbereich nachgewiesen werden. Berlin Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) 2014 DGZfP-Berichtsband 148 978-3-940283-61-0 DGZfP-Jahrestagung 2014 Potsdam, Germany 26.05.2014 28.05.2014 1 7 urn:nbn:de:kobv:b43-313317 http://creativecommons.org/licenses/by-nd/3.0/de/ 2016-02-20 OPUS4-21997 Beitrag zu einem Tagungsband von der Ehe, Kerstin; Jaunich, Matthias; Böhning, Martin; Goering, Harald; Wolff, Dietmar Detection of structural changes of (U)HMW-PE induced by gamma irradiation Halle / Saale Druck-Zuck GmbH 2010 14th International conference "Polymeric materials" - P.2010 (Proceedings) 978-3-86829-282-4 14th International conference "Polymeric materials" Halle (Saale), Germany 2010-09-15 2010-09-17 1 6 2016-02-19 OPUS4-23887 Beitrag zu einem Tagungsband Jaunich, Matthias; von der Ehe, Kerstin; Wolff, Dietmar; Völzke, Holger; Stark, Wolfgang Understanding the low temperature properties of rubber seals Rubbers are widely used as main sealing materials for containers for low and intermediate level radioactive waste and as additional component to metal seals in spent fuel and high active waste containers. The save encapsulation of the radioactive container inventory has to be guaranteed according to legislation and appropriate guidelines for long term storage periods as well as down to temperatures of -40 °C during transport. Therefore the understanding of failure mechanisms that lead to leakage at low temperatures is of high importance. It is known that the material properties of rubbers are strongly temperature dependent. At low temperatures this is caused by the rubber-glass transition (abbr. glass transition). During continuous cooling the material changes from rubber-like entropy-elastic to stiff energy-elastic behaviour, that allows nearly no strain or retraction, due to the glass transition. Hence rubbers are normally used above their glass transition but the minimum working temperature limit is not defined precisely, what can cause problems during application. Therefore the lower operation temperature limit of rubber seals should be determined in dependence of the material properties. The results of Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) are combined with the results of standardized measurements as the compression set according to ISO 815. To reduce the test time of the standard tests a faster technique was developed. Additionally, the breakdown temperature of the sealing function of complete O-ring seals is measured in a component test setup to compare it with the results of the other tests. The experimental setup is capable of measuring the leakage rate at low temperatures by the pressure rise method. A fluorocarbon rubber (FKM) was selected for this investigation as it is often used for radioactive waste containers. Some materials (seals and test sheets) were purchased from a commercial seal producer and some materials were compounded and cured at BAM in form of rubber sheets. PATRAM 2010 PATRAM 2010 - 16th International symposium on the packaging and transport of radioactive materials (Proceedings) PATRAM 2010 - 16th International symposium on the packaging and transport of radioactive materials London, UK 2010-10-03 2010-10-08 1 7 (Session T41 / Paper 169) 2016-02-19 OPUS4-24015 Zeitschriftenartikel Jaunich, Matthias; von der Ehe, Kerstin; Wolff, Dietmar; Völzke, Holger; Stark, Wolfgang Understanding low temperature properties of elastomer seals Elastomers are widely used as the main sealing materials for containers for low and intermediate level radioactive waste and as an additional component to metal seals in spent fuel and high active waste containers. The safe encapsulation of the radioactive container inventory has to be guaranteed according to regulation and appropriate guidelines for long term storage periods as well as for temperatures as low as -40°C during transport. Therefore, the understanding of failure mechanisms that lead to leakage at low temperatures is of high importance. It is known that the material properties of elastomers are strongly temperature dependent. At low temperatures, this is caused by the rubber-glass transition (abbreviated: glass transition). During continuous cooling, the material changes from a rubber-like entropy elastic to a stiff energy elastic behaviour, which allows nearly no strain or retraction. Hence, rubbers are normally used above their glass transition, but the minimum working temperature limit is not defined precisely; this can cause problems during the above noted applications. Therefore, the lower operation temperature limit of elastomer seals must be determined in dependence of the material properties. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) are combined with standardised measurements to determine the compression set according to ISO 815. To reduce the test time of the standard tests, a faster technique than normally used was developed. Additionally, the breakdown temperature of the sealing function of complete O ring seals was measured in a component test set-up to compare it with the results of the other tests. The experimental set-up is capable of measuring the leakage rate at low temperatures by the pressure rise method. A fluorocarbon rubber (FKM) was selected for this investigation as it is often used for radioactive waste containers. The materials (seals and test sheets) were purchased from a commercial seal producer. Ashford Ramtrans Publ. 2011 Packaging, transport, storage & security of radioactive materials (RAMTRANS) 22 2 83 88 10.1179/1746510911Y.0000000004 2016-02-19 OPUS4-32699 Beitrag zu einem Tagungsband Beckmann, Jörg; Schade, U.; von der Ehe, Kerstin; Jaunich, Matthias; Wolff, Dietmar; Aziz, E. F. THz and Mid IR Fourier transform spectroscopy on polyethylene irradiated with Gamma- Co60 radiation THz and mid IR spectroscopy of high molecular PE (HMW) and ultra high molecular PE (UHMW) reveals modifications of the molecular structure induced by γ-Co60 radiation. UHMW-PE and HMW-PE can be distinguished. The integral absorption in the B1u THz-region can quantitatively describe the amorphization of crystallinity. The formation of trans vinylene unsaturations and the decay of vinyl can be followed by mid IR spectroscopy 2014 IRMMW-THz 2014 - 39th International conference on infrared, millimeter, and terahertz waves 978-1-4799-3877-3 IRMMW-THz 2014 - 39th International conference on infrared, millimeter, and terahertz waves Tucson, Arizona, USA 14.09.2014 19.09.2014 IEEE Catalog No.: CFP14IMM-ART 1 2 10.1109/IRMMW-THz.2014.6956355 2016-02-20 OPUS4-42399 Zeitschriftenartikel Kömmling, Anja; Chatzigiannakis, E.; Beckmann, Jörg; Wachtendorf, Volker; von der Ehe, Kerstin; Braun, Ulrike; Jaunich, Matthias; Schade, U.; Wolff, Dietmar Discoloration Effects of High-Dose gamma-Irradiation and Long-Term Thermal Aging of (U) HMW-PE Two polyethylene types with ultra-high (UHMWPE) and high molecular weight (HMW-PE) used as neutron radiation shielding materials in casks for radioactive waste were irradiated with doses up to 600 kGy using a 60Co gammasource. Subsequently, thermal aging at 125∘C was applied for up to one year. Degradation effects in the materials were characterized using colorimetry, UV-Visspectroscopy, IR spectroscopy, and DSC. Both materials exhibited a yellowing upon irradiation.The discoloration of UHMW-PE disappeared again after thermal aging.Therefore, the yellowing is assumed to originate fromannealable color centers in the formof free radicals that are trapped in the crystalline regions of the polymer and recombine at elevated temperatures. For the antioxidantcontaining HMWPE, yellowing was observed after both irradiation and thermal aging. The color change was correlated mainly to decomposition products of the antioxidant in addition to trapped radicals as in UHMW-PE. Additionally, black spots appeared after thermal aging of HMW-PE. Hindawi 2017 International Journal of Polymer Science 2017 Article ID 1362491 1 10 urn:nbn:de:kobv:b43-423992 10.1155/2017/1362491 http://creativecommons.org/licenses/by/3.0/de/deed.de 2017-10-09