TY - JOUR A1 - Qiao, Linan A1 - Nagelschmidt, Sven A1 - Herbrich, Uwe A1 - Keller, Christian T1 - Introduction of a Power Law Time-Temperature Equivalent Formulation for the Description of Thermorheologically Simple and Complex Behavior N2 - Abstract: In this work, a conceptual framework is suggested for analyzing thermorheologically simple and complex behavior by using just one approach. Therefore, the linear relation between master time and real time which is required in terms of the time-temperature superposition principle was enhanced to a nonlinear equivalent relation. Furthermore, we evaluate whether there is any relation among well-known existing time-temperature equivalent formulations which makes it possible to generalize different existing formulations. For this purpose, as an example, the power law formulation was used for the definition of the master time. The method introduced here also contributes a further framework for a unification of established time-temperature equivalent formulations, for example the time-temperature superposition principle and time-temperature parameter models. Results show, with additional normalization conditions, most of the developed time-temperature parameter models can be treated as special cases of the new formulation. In the aspect of the arrow of time, the new defined master time is a bended arrow of time, which can help to understand the corresponding physical meaning of the suggested method. KW - bended arrow of time KW - time-temperature superposition principle KW - time-temperature equivalent formulation PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-543800 VL - 15 IS - 3 SP - 1 EP - 11 PB - MDPI AN - OPUS4-54380 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nagelschmidt, Sven A1 - Herbrich, Uwe A1 - Probst, Ulrich A1 - Wolff, Dietmar T1 - Evaluation of test results with regard to ageing mechanisms of metal seals in casks for dry storage of spent nuclear fuel T2 - Ageing of Materials & Structures 2014 CY - Delft, Netherlands DA - 2014-05-26 PY - 2014 AN - OPUS4-30675 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nagelschmidt, Sven A1 - Probst, Ulrich A1 - Herbrich, Uwe A1 - Wolff, Dietmar T1 - Evaluation of test results with regard to ageing mechanisms of metal seals used in casks for spen nuclear fuel T2 - CEA Workshop 2014 - Predictive approach of sealing CY - Paris, Frankreich DA - 2014-10-13 PY - 2014 AN - OPUS4-31792 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wolff, Dietmar A1 - Jaunich, Matthias A1 - Probst, Ulrich A1 - Nagelschmidt, Sven T1 - Understanding the long-term behavior of sealing systems and neutron shielding material for extended dry cask storage N2 - In Germany, the concept of dry interim storage in dual purpose metal casks before disposal is being pursued for spent nuclear fuel (SF) and high active waste (HAW) management. However, since there is no repository available today, the initially planned and established dry interim storage license duration of up to 40 years will be too short and its extension will become necessary. For such a storage license extension it is required to assess the long-term performance of SF and all safety related storage system components in order to confirm the viability of extended storage. The main safety relevant components are the thick-walled dual purpose metal casks. These casks consist of a monolithic cask body with integrated neutron shielding components (polymers, e.g. polyethylene) and a monitored double lid barrier system with metal and elastomeric seals. The metal seals of this bolted closure system guarantee the required leak-tightness whereas the elastomeric seals allow for leakage rate measurement of the metal seals. This paper presents an update on running long-term tests on metal seals at different temperatures under static conditions over longer periods of time. In addition, first results of our approach to understand the aging behavior of different elastomeric seals and neutron radiation shielding material polyethylene are discussed. T2 - PSAM 12 - Probabilistic safety assessment and management CY - Honolulu, Hawaii, USA DA - 22.06.2014 KW - Extended storage KW - Dual purpose casks KW - Metal seals KW - Elastomeric seals KW - Neutron shielding material PY - 2014 SP - 1 EP - 9 AN - OPUS4-32072 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nagelschmidt, Sven A1 - Probst, Ulrich A1 - Völzke, Holger A1 - Wolff, Dietmar T1 - Long-term investigations of metal seals for storage casks of radioctive materials N2 - The Bundesanstalt für Materialforschung und –prüfung (BAM) is a federal institute for materials research and testing in Germany and has been involved in the qualification and safety evaluation procedures of metal seals from the early beginning of the interim storage licensing procedures for radioactive materials, stored in dual purpose casks. Regarding this subject, BAM investigates the long-term behavior of metal seals under the influence of temperature using experimental data and analytical approaches. The development of numerical models is in progress as well. Systematic experimental investigations performed by BAM indicate a continuous decrease of the remaining seal force and the usable resilience considering the leak tightness. Hence, there is a fundamental interest of describing time and temperature dependency to gain predictable values for the long-term behavior and to achieve reliable results with help of short-term tests. The paper gives an overview about the sealing principle, test program and test results of metal seals of the type HELICOFLEX® HN200. The aging effect, respectively the long-term behavior in dependency of time and temperature, are introduced for two different outer liner materials, aluminum and silver. T2 - PVP ASME Conference CY - Vancouver, Canada DA - 17.07.2016 KW - Long-Term Behaviour KW - Metal Seal KW - Metal Gasket PY - 2016 SN - 978-0-7918-5045-9 VL - 7 SP - 63596-1 EP - 63596-5 AN - OPUS4-38039 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Qiao, Linan A1 - Nagelschmidt, Sven A1 - Herbrich, Uwe T1 - Application of a Modified Arrhenius Equation to Describe the Time-Temperature Equivalence in Relaxation Analysis of Metal Seals N2 - For the application of the time-temperature superposition principle a suitable relation is needed to describe the time-temperature shift factor α. Therefore, the Arrhenius equation is widely used due to its simple form and often leads to suitable results. Where, the Arrhenius equation presents a linear relation for the temperature-dependent shift factor in logarithmic scale ln(α) with the absolute inverse temperature (1/ϑ). However, in cases with a large temperature range which eventually include more complex reaction processes, the functional relation between ln(α) and (1/ϑ) is nonlinear in the ‘Arrhenius plot’. In those cases, the monotone change of the nonlinear range in the ‘Arrhenius plot’ can be interpreted as a transient range between two approximately linear or constant regions. An extended application of the modified Arrhenius equation from Nakamura (1989) is presented in this study for this transient range. The introduced method was applied to describe the time-temperature equivalence in the relaxation analysis of restoring seal force of metal seals, which are used in lid-systems of transport and interim storage casks for radioactive materials. But, the method is widely valid and can be used for different objectives which are characterized by thermorheologically simple behavior with nonlinear sensitivity to inverse temperature. KW - Metal seals KW - TTS principle KW - Arrhenius equation KW - Non-linear Arrhenius behavior KW - Relaxation analysis KW - Seal force PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-446759 UR - http://www.davidpublisher.org/index.php/Home/Article/index?id=33931.html SN - 1934-7359 VL - 11 IS - 9 SP - 853 EP - 861 PB - David Publishing Company CY - USA, NY 10989, Valley Cottage AN - OPUS4-44675 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Qiao, Linan A1 - Herbrich, Uwe A1 - Nagelschmidt, Sven T1 - Describing Relaxation Behavior of Metal Seals Using Time-Temperature Superposition Principle N2 - In order to study the time- and temperature-dependent long-term behavior of metal seals, experimental investigations on special metal seals have been carried out at five different temperatures in a temperature range between 20 and 150°C for more than 7 years. Experimental results indicate a noticeable change of relevant sealing properties like seal force and usable resilience depending on time and temperature. In this study, the metal seals are treated as a homogeneous material block so that the identified decrease in seal force can be treated as a material relaxation effect. For the time-dependent behavior of seal force, an enhanced power-law model is introduced for the first time and is compared with the currently used power-law model. Additionally, regarding the influence of temperature, the timetemperature superposition principle is applied to metal seals for the first time with a clearly defined process. Thus, possible mistakes in the application of principle could be avoided. The introduced method is widely available for different applications regarding effects the principle with time and temperature. KW - Metal seals KW - Relaxation KW - Thermo-viscoplasticity KW - Time-temperature superposition PY - 2018 UR - https://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0001424 U6 - https://doi.org/10.1061/(ASCE)EM.1943-7889.0001424 SN - 0733-9399 VL - 144 IS - 4 SP - 04018016-1 EP - 04018016-8 PB - American Society of Civil Engineers AN - OPUS4-44676 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nagelschmidt, Sven A1 - Herbrich, Uwe A1 - Probst, Ulrich A1 - Wolff, Dietmar ED - Van Breugel, K. ED - Koenders, E.A.B. T1 - Evaluation of test results with regard to ageing mechanisms of metal seals in casks for dry storage of spent nuclear fuel N2 - Metal seals are widely used for extreme applications, e.g. in dual-purpose casks for dry interim storage of spent nuclear fuel in Germany. Due to the fact that interim storage must be safe at least for the approved period of 40 years there is a major interest to investigate the long-term behaviour and ageing mechanisms of metal seals. Experimental analyses indicate a time and temperature dependency of seal characteristics. This dependency was researched with a time- and temperature parameterization based up on Larson-Miller. The paper describes the derivation of the material parameter C from test results and the applicability of the Larson-Miller-Relationship for those metal seals in principle. Overall a constant material parameter C was not. Nevertheless, an approach comparable to the Larson-Miller-Parameter was developed. T2 - 1st Ageing of materials & structures 2014 conference CY - Delft, The Netherlands DA - 26.05.2014 KW - Metal seal KW - Ageing KW - Larson-Miller-Parameter KW - Aluminium KW - Silver KW - Larson and Miller relationship KW - Casks KW - Spent fuel PY - 2014 SN - 978-94-6186-313-3 SP - 126 EP - 133 AN - OPUS4-30821 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nagelschmidt, Sven A1 - Herbrich, Uwe A1 - Qiao, Linan T1 - Applicability of developed calculation models to predict long-term behavior of metal seals – Necessary scope of tests N2 - The long-term sealing behavior of metal seals, assembled in the lid system of casks for transportation and storage of radioactive materials, has been investigated. For that purpose, phenomenological models describing the time- and temperature dependent behavior have been introduced by BAM since 2016, e.g. by using the time-temperature superposition principle. Results have shown that these models describe the relaxation behavior adequately and are suitable for extrapolations. In this work, the applicability of these models is checked by analyzing the necessary scope of tests, which must be carried out to get sufficient information about the long-term behavior of metal seals based on short-term tests. T2 - Waste Management Conference CY - Phoenix, Arizona, USA DA - 03.03.2019 KW - Metal seal KW - Time-temperature superposition principle KW - Transportation and storage cask KW - Long-term interim storage PY - 2019 SP - 19311, 1 EP - 6 AN - OPUS4-48353 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Herbrich, Uwe A1 - Nagelschmidt, Sven A1 - Weber, Wolfgang A1 - Wolff, Dietmar A1 - Völzke, Holger T1 - Die sicherheitstechnische Behälterbegutachtung für die trockene Zwischenlagerung bestrahlter Brennelemente aus Sicht der BAM T2 - Jahrestagung Kerntechnik 2013 CY - Berlin, Germany DA - 2013-05-14 PY - 2013 SP - 1 EP - 6(?) AN - OPUS4-28585 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Völzke, Holger A1 - Wolff, Dietmar A1 - Probst, Ulrich A1 - Nagelschmidt, Sven A1 - Schulz, Sebastian T1 - Long-term performance of metal seals for transport and storage casks N2 - Dual purpose casks for the transportation and storage of spent nuclear fuel and other radioactive materials require very high leak-tightness of lid closure Systems under accident conditions as well as in the long-term to prevent activity release. For that purpose metal seals of specific types with an inner helical spring and outer metal liners are widely used and have shown their excellent performance if certain quality assurance requirements for fabrication and assembling are satisfied. Well defined surface roughness, clean and dry inert conditions are therefore essential. No seal failure in a loaded cask happened under these conditions until today. Nevertheless, the considered and licensed Operation period is limited and all safety assessments have been performed and approved for this period of time which is 40 years in Germany so far. But in the meantime longer storage periods might be necessary for the future and therefore additional material data will be required. BAM is involved in the qualification and evaluation procedures of those seals from the early beginning. Because long-term tests are always time consuming BAM has early decided to perform additional tests with specific test seal configurations to gain a better understanding of the long-term behavior with regard to seal pressure force, leakage rate and useable resilience which is safety relevant mainly in case of accidental mechanical loads inside a storage facility or during a subsequent transport. Main test parameters are the material of the outer seal jacket (silver or aluminum) and the temperature. This paper presents the BAM test program including an innovative test mock-up and most recent test results. Based on these data extrapolation models to extended time periods are discussed, and also future plans to continue tests and to investigate seal behavior for additional test parameters are explained. T2 - PATRAM 2013 - 17th International symposium on the packaging and transportation of radioactive materials CY - San Francisco, CA, USA DA - 18.08.2013 PY - 2013 SP - 1 EP - 13 PB - Omnipress AN - OPUS4-30136 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Völzke, Holger A1 - Probst, Ulrich A1 - Wolff, Dietmar A1 - Nagelschmidt, Sven A1 - Schulz, Sebastian T1 - Investigations on the long term behavior of metal seals for spent fuel storage casks N2 - Metal seals are in common use as an essential component for the leak tight closure of transport and storage casks for spent fuel and vitrified high active waste from reprocessing. They are placed between the massive monolithic cask body made of ductile cast iron or forged steel and the primary and secondary lids, which are fixed with screws around the lid circumference, in order to ensure long term safe enclosure of the radioactive cask inventory. Hereby, long term reliable pressure forces in combination with a tight surface contact are as important as well maintained seal and surface qualities and dry and clean conditions during seal assembly and operation. A few years ago BAM started systematic investigation on the long term seal behavior with re-spect to longer storage periods and seal behavior in accidental cask scenarios with dynamic de-formations of the seal groove geometry or short term drop in pressure force up to lid lifting. BAM has developed test flanges for seals with full scale cross section diameter but much small-er outer diameter to gain representative data for metal-sealed lid systems. They are placed in appropriate testing machines for relevant mechanical loading under static and dynamic condi-tions with the ability to measure the standard helium leakage rate continuously during each test phase. This paper focuses on BAM long term tests of different seal types with aluminum and silver jackets at three different temperatures of +20°C, +100°C and +150°C under static conditions over longer periods of time. Due to creeping effects, a reduction of the pressure force does ap-pear during loading and unloading depending on prior holding times. So far, test results of up to 2 years indicate a clear correlation between seal pressure forces and holding time, temperature and seal type allowing for extrapolating to much longer periods of time. The paper presents basic correlations, test and evaluation procedures as well as important provisional results and gives an outlook on further investigations. T2 - 52nd INMM Annual meeting CY - Palm Desert, CA, USA DA - 17.07.2011 PY - 2011 SP - 1 EP - 9 AN - OPUS4-24173 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Völzke, Holger A1 - Probst, Ulrich A1 - Wolff, Dietmar A1 - Nagelschmidt, Sven A1 - Schulz, Sebastian T1 - Seal and closure performance in long term storage T2 - PSAM 11 ESREL 2012 - 11th International probabilistic safety assessment and management conference & The annual european safety and reliability conference CY - Helsinki, Finland DA - 2012-06-25 KW - Metal seal KW - Interim storage KW - Long term performance PY - 2012 SP - 1 EP - 8(?) AN - OPUS4-26175 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weber, Mike A1 - Zencker, Uwe A1 - Wolff, Dietmar A1 - Völzke, Holger A1 - Herbrich, Uwe A1 - Nagelschmidt, Sven T1 - Numerical analysis of cask accident scenarios in storage facilities N2 - Existing spent nuclear fuel (SF) and high active waste (HAW) management policies and practices worldwide are the result of past presumptions that sufficient reprocessing and/or disposal capacity would be available in the near term. Consequently, in the past many countries have developed specific solutions for different periods of time due to their individual national nuclear policies. In Germany the concept of dry interim storage in dual purpose metal casks before disposal is being pursued for SF and HAW management and transport and storage licenses have been issued accordingly. The current operation licenses for existing storage facilities have been granted for a storage period of up to 40 years. This concept has demonstrated its suitability for over 20 years so far. Relevant safety requirements have been assessed for the short-term as well as for the long-term for site-specific operational and accidental storage conditions. But in the meantime significant delays in the national repository siting procedure occurred which will make extended storage periods necessary in the future. T2 - PATRAM 2013 - 17th International symposium on the packaging and transportation of radioactive materials CY - San Francisco, CA, USA DA - 18.08.2013 KW - Numerical analysis KW - Interim storage KW - Cask accident scenario PY - 2013 SP - Session H, Paper 202, 1 EP - 9 PB - Omnipress AN - OPUS4-30227 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weber, Mike A1 - Zencker, Uwe A1 - Wolff, Dietmar A1 - Völzke, Holger A1 - Herbrich, Uwe A1 - Nagelschmidt, Sven T1 - Numerical analysis of cask accident scenarios in storage facilities N2 - Mechanical drop test scenarios for Type B (U) packages according to the IAEA regulations have to be carried out onto the so-called “unyielding target” (usually with cask impact limiters) and onto the puncture bar respectively. They are predefined and do not require any further investigation of scenarios that really could happen on transportation routes. Cask accident scenarios in the framework of approval procedures for interim storage sites are derived from a detailed analysis of the handling procedures necessary from arrival of cask at the site to its storing position. In that case, casks are usually handled without impact limiters. Dependent on possible drop heights, drop positions and floor properties, conservative cask accident scenarios are derived for further safety proofs. According to the mechanical assessment concept of the considered approval procedure numerical calculations have to be provided by the applicant to demonstrate mechanical cask safety. Stresses and strains in the cask body as well as in the lid System have to be identified and assessed. Using the example of a 3-mvertical-drop of a transport and storage cask for spent fuel elements onto the floor construction made of damping concrete covered by screed, BAM developed a finite element model. The finite element code ABAQUS/Explicit™ was used. Results of experimental investigations are not available. Therefore parameter studies are necessary to identify the sensitivity of the finite element model to significant Parameters and to verify the finite element models according to the requirements of the Guidelines for the Numerical Safety Analyses for the Approval of Transport and Storage Casks for Radioactive Materials (BAM GGR-008). The paper describes the modeling of the material behavior and attachment of bottom side cask components. Questions concerning the modeling of a crack length limiting reinforcement in the screed layer are discussed. The influence of the mesh density of the screed layer and its strength is considered as well. Finally, the developed finite element model can be used for a numerical safety assessment. It can help to understand the complex mechanisms of the interaction between the cask components and floor construction. T2 - WM2014 Conference CY - Phoenix, Arizona, USA DA - 02.03.2014 KW - Numerical analysis KW - Interim storage KW - Cask accident scenario PY - 2014 SN - 978-0-9836186-3-8 SP - Paper 14541, 1 EP - 12 AN - OPUS4-31516 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Völzke, Holger A1 - Wolff, Dietmar A1 - Probst, Ulrich A1 - Nagelschmidt, Sven A1 - Schulz, Sebastian T1 - Long term performance of metal seals for transport and storage casks N2 - Dual purpose casks for the transportation and storage of spent nuclear fuel and other radioactive materials require very high leak tightness of lid closure systems under accident conditions as well as in the long term to prevent activity release. For that purpose metal seals of specific types with an inner helical spring and outer metal liners are widely used and have shown their excellent performance if certain quality assurance requirements for fabrication and assembling are satisfied. Well defined surface roughness, clean and dry inert conditions are therefore essential. No seal failure in a loaded cask happened under these conditions until today. Nevertheless, the considered and licensed operation period is limited and all safety assessments have been performed and approved for this period of time which is 40 years in Germany so far. However, in the meantime longer storage periods might be necessary for the future and therefore additional material data will be required. BAM is involved in the qualification and evaluation procedures of those seals from the early beginning. Because long term tests are always time consuming BAM has early decided to perform additional tests with specific test seal configurations to gain a better understanding of the long term behaviour with regard to seal pressure force, leakage rate and useable resilience which is safety relevant mainly in case of accidental mechanical loads inside a storage facility or during a subsequent transport. Main test parameters are the material of the outer seal jacket (silver or aluminium) and the temperature. This paper presents the BAM test program including an innovative test mock-up and most recent test results. Based on these data extrapolation models to extended time periods are discussed, and also future plans to continue tests and to investigate seal behaviour for additional test parameters are explained. KW - Metal Seal KW - Spent Fuel KW - Storage KW - Ageing KW - Cask KW - Leak tightness PY - 2014 U6 - https://doi.org/10.1179/1746510914Y.0000000057 SN - 1746-5095 SN - 1746-5109 SN - 0957-476X VL - 25 IS - 1 SP - 8 EP - 15 PB - Ramtrans Publ. CY - Ashford AN - OPUS4-32327 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nagelschmidt, Sven A1 - Herbrich, Uwe A1 - Probst, Ulrich A1 - Wolff, Dietmar A1 - Völzke, Holger T1 - The Results and Analyses in Terms of Aging Mechanisms of Metal Seals in Casks for Dry Storage of SNF - 14255 T2 - Waste Management Conference 2014 CY - Phoenix, AZ, USA DA - 2014-03-02 PY - 2014 AN - OPUS4-30676 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -