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 - Grelle, Tobias A1 - Wolff, Dietmar A1 - Probst, Ulrich A1 - Jaunich, Matthias A1 - Völzke, Holger T1 - Investigation of the time and temperature dependent behavior of metal seals in radioactive waste containers N2 - The Bundesanstalt für Materialforschung und –Prüfung (BAM) runs an investigation program on the long-term behavior of multi-component metal seals. Such seals are used in a wide area of applications including transport and storage casks for spent nuclear fuel and high level radioactive waste. The seal function is mainly based on the compression of the inner helical spring, which generates the necessary seal force to keep the sealing surfaces in close contact. This in turn leads to a plastic deformation of the outer jacket of the seal, comprised of highly ductile aluminum or silver that adapts to the sealing surfaces of cask body and bolted lid, thus providing high Level leak tightness. In Germany, those casks are licensed for Interim storage periods of up to 40 years or more if extended Interim storage would become necessary before a final repository is available. Thus, the sealing performance has to be evaluated, including factors like elevated temperature due to decay heat or mechanical loads due to transport under normal as well as accident conditions. Long-term investigations at BAM have been running over the last nine years to identify and evaluate the seal performance by measuring the remaining seal force, the useable resilience and the leakage rate after various time intervals at temperatures ranging from room temperature up to 150 °C. It was found that the seal force and useable resilience decrease with time and temperature, caused by creep deformation of the outer jacket. In order to obtain an analytical description for the seal behavior and to achieve more information on the material behavior under application conditions a comprehensive investigation program with Focus on aluminum as outer jacket material was launched. The program includes material investigations such as compression and tension creep tests with representative basic materials. An additional test setup allows for the continuous measurement of the remaining seal force at temperatures of up to 150 °C. Furthermore, seal segments are compressed and stored in heating chambers, thus producing segments at different stages of the aging process. The segments are investigated regarding the development of the contact area width, jacket thickness and microstructural changes. This data will be used to develop material models and an analytical description of the time and temperature dependent long-term sealing behavior. This paper explains the current status of gained test results and modelling approaches and closes with an outlook to the future Project plans. T2 - ASME 2018 Pressure Vessels and Piping Conference CY - Prague, Czech Republic DA - 15.07.2018 KW - Metal seal KW - Creep KW - Long-term behavior PY - 2018 SP - PVP2018-84584, 1 EP - 6 AN - OPUS4-46110 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Völzke, Holger A1 - Wolff, Dietmar A1 - Barnabas, I. A1 - Ordogh, M. A1 - Shirai, K. A1 - Saegusa, T. A1 - Cho, C.-H. A1 - Kook, D. A1 - Lopez, J. F. A1 - Conde, J. M. A1 - Alejano, C. A1 - Lloret, M. A1 - Quecedo, M. A1 - Shea, J. A1 - Ross, P. J. A1 - White, N. A1 - Rossiter, G. A1 - Hodgson, Z. A1 - Sorenson, K. A1 - McConnell, P. A1 - Hanson, B. ED - Sorenson, K. ED - Shirai, K. ED - Völzke, Holger T1 - Extended storage collaboration program - International subcommittee report - International perspectives on technical data gaps associated with extended storage and transportation of used nuclear fuel N2 - The US Electric Power Research Institute (EPRI) chartered a volunteer committee in November 2009 to share information and data related to extended storage and subsequent transportation of used nuclear fuel. This committee is named the Extended Storage Collaboration Program (ESCP) and was initially comprised of representatives from industry (fuel and cask vendors, utilities, the Nuclear Energy Institute, and EPRI), as well as government (e.g., US Department of Energy) and the US Nuclear Regulatory Commission. The primary motivation for establishing this committee was the recognition that used fuel will need to be stored past the regulatory licensing timeframe. In the US, this is mainly a result of the cessation of licensing activities for the planned Yucca Mountain repository. Recognizing that there is a global interest in extended storage and transportation, the International Subcommittee was established in December 2010 to extend the reach of ESCP internationally in order to fully address extended storage and transportation issues, as they apply to different systems, national policies, and regulations around the world. This Subcommittee serves to deepen the overall understanding of degradation mechanisms associated with storage and transportation systems, expand the access to data and programs related to extended storage and transportation, and strengthen the overall technical basis for programmatic decisions. The International Subcommittee established three basic objectives: 1. Conduct a technical data gap survey 2. Assess opportunities to leverage specific research to benefit the larger international group 3. Integrate our work with relevant International Atomic Energy Agency (IAEA) committee work This report constitutes completion of Objective #1. The International Subcommittee worked to identify and prioritize technical gaps that need to be addressed to support licensing activities within their own countries. Because there are varying types of storage and transportation system designs, national policies and regulations, there are identified commonalities as well as differences that stress the importance of this work on an international scale. Section 5 of this report identifies and prioritizes all of the identified data gaps for each participating organization. However, important data gaps were identified that had a consensus of opinion of being a high priority. These technical gaps, as a function of storage system component are: 1. Fuel – hydride effects on fuel cladding and retrievability of fuel after storage 2. Canister – general canister corrosion and stress corrosion cracking of canister closure welds, particularly in marine environments 3. Closure – degradation of bolts and seals (metallic and organic) 4. Overpack – concrete degradation Dry storage systems were originally designed for limited periods. With extended dry storage, it is generally believed that used fuel can be stored safely and securely past the regulatory time period. However, the technical arguments need to be made to justify extended licensing periods. Addressing the data gaps will provide the necessary arguments to justify license extensions. In the development of this report, the International Subcommittee met five times over a period of 18 months to work through the issues of identifying and prioritizing the data gaps, and discussing of technical issues as they pertain to the safety of used fuel storage and transportation. The meeting locations and dates were: 1. Vienna June 2010 2. London October 2010 3. Charlotte December 2010 4. Berlin June 2011 5. Charlotte December 2011 This report is not meant to be a technical document. Rather, it is an overview of country regulatory policy, a review of in-country operational status and used fuel inventory, followed by a role-up of identification and prioritization of technical data gaps. Technical documents that were used in the data gap assessments are referenced. It is important to note that this document represents only the opinions of the contributors. This document in no way represents any official country position. The organizations providing support to the writing of this report are: Germany: - Bundesanstalt für Materialforschung und -prüfung Hungary: - Radioaktiv Julladekokat Kezelo Kozhasznu - Som System Kft. Japan: - Central Research Institute of Electric Power Industry South Korea: - Korea Atomic Energy Research Institute - Korea Radioactive Waste Management Corporation Spain: - Consejo de Seguridad Nuclear - ENRESA Empresa Nacional de Residuos Radiactivos - ENUSA Industrias Avanzadas United Kingdom: - EDF Energy - National Nuclear Laboratory Ltd. United States: - Pacific Northwest National Laboratory - Sandia National Laboratories KW - Used/spent fuel dry storage KW - Used/spent fuel transportation KW - Extended used/spent nuclear fuel storage KW - High burnup spent fuel storage and transportation KW - Spent fuel storage and transportation KW - Extended Storage Collaboration Program (ESCP) KW - ESCP International Subcommittee PY - 2012 UR - https://www.epri.com/research/products/1026481 N1 - This final report was prepared as part of the volunteer Extended Storage Collaboration Program (ESCP). VL - 1026481 SP - 1 EP - 132 PB - Electric Power Research Institute (EPRI) CY - Palo Alto, CA, USA AN - OPUS4-27405 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -