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A state-of-the-art (SOTA) review on characterisation of spent nuclear fuel (SNF) properties in terms of source term and inventory assessment (neutron, gamma-ray emission, decay heat, radionuclide inventory, elemental content) and in terms of out-of-core fuel performance (cladding performance and fuel integrity in view of the safety criteria for SNF interim storage, transport and canister packaging) using several numerical and experimental approaches and methodologies is presented. This SOTA report is a result of the spent fuel characterisation (SFC) work package as part of the European Joint Programme on Radioactive Waste Management (EURAD), which offers an overview of the status of knowledge in the field of SNF characterisation and assessment during the pre-disposal phase. The document aims to focus on the current safety-significant gaps and related challenges, providing a direct link to the goals of the mandated actors of EURAD. The report is expected to be used by all EURAD colleagues in their national programmes as a key resource for knowledge management programmes and to contribute to demonstrating and documenting the state-of-the-art.
The presentation provides an overview about the understanding of fuel cladding failure mechanisms dominated by hydride embrittlement during long term dry storage. A currently launched research project focuses on the development of a fracture mechanics approach to describe brittle failure of fuel cladding during long term interim storage (BRUZL)“. Finally, the BAM contribution to the current European Joint Program (EJP) on radioactive waste management is illustrated.
The presentation focuses on the latest developments of the German nuclear waste management policy including restructering of responsible organizations and the restart of the repository site selection process for high level radioactive waste.
The second part illustrates latest results of long term investigations of metal seals at BAM with regard to extended interim storage periods.
This presentation starts with a brief overview about the current situation of spent nuclear fuel and high level waste storage in Germany followed by a discussion of the expected timeline towards final disposal. Furthermore an overview is presented about research programmes for radioactive waste disposal and also extended interim storage issues due to the delay of the national repository siting procedure. In the second part of the presentation BAM research activities related to extended interim storage are addressed. This includes the status and preliminary results of proactive R&D projects concerning metal seals, degradation effects of polymers used as neutron shielding materials and finally elastomer seals.
Bisherige Betriebserfahrungen und Erkenntnisse lassen die grundsätzliche Eignung der Transport- und Lagerbehälter auch über 40 Jahre hinaus erwarten.
Eine Verlängerung der genehmigten Zwischenlagerdauer erfordert eine Neugenehmigung. Hierbei sind die zu diesem Zeitpunkt sicherheitstechnisch relevanten Eigenschaften der tatsächlich vorhandenen Inventare und Behälter zu berücksichtigen.
Sicherheitstechnische Nachweise sind auf Grundlage belastbarer Daten und Erkenntnisse zu führen. Diese müssen rechtzeitig verfügbar sein (z.B. Betriebserfahrungen oder zusätzliche F&E-Programme z.B. zu Behälterdichtsystemen oder Inventarverhalten).
Alterungsmanagementprogramme und periodische Sicherheits-überprüfungen während der Zwischenlagerung haben sowohl für die verlängerte Zwischenlagerung als auch für nachfolgende Transporte eine erhebliche Bedeutung.Die Schaffung eines spezifischen Regelwerks für die verlängerte Zwischenlagerung von Transport- und Lagerbehältern und deren nachfolgendem Abtransport unter Berücksichtigung der Anforderungen aus beiden Verwendungsbereichen erscheint sinnvoll.
Eine verlängerte Zwischenlagerung dient ausschließlich der Überbrückung bis zur Endlagerung. Hierbei sollten die bestehenden Behälter und Inventare frühzeitig in die Überlegungen zur Definition von Anforderungen für die Endlagerung einbezogen werden.
Die internationalen Entwicklungen und Untersuchungen im Bereich der längerfristigen Zwischenlagerung sollten zur Nutzung von Synergieeffekten weiter verfolgt, ausgewertet und mitgestaltet werden.
Due to delays in the site-selection procedure to establish a deep geological repository for spent nuclear fuel and high level waste and in construction of the already licensed Konrad-repository for low and intermediate level waste without heat generation, extended periods of interim storage become more relevant in Germany. BAM is involved in most of the cask licensing procedures and especially responsible for the evaluation of cask-related long-term safety issues.
The long-term performance of elastomer seals for lid Systems of transport and storage casks whether used as auxiliary seals in spent fuel caslcs or as primary seals for low and intermediate level waste packages is an important issue in this context (Jaunich, 2013; Jaunich, 2014; Kömmling, 2015). The polymeric structure of these seals causes a complex mechanical behaviour with time-dependent elasticity reduction and loss of elastic recovery.
The paper presents first results of a comprehensive test Programme consisting of several static and dynamic mechanical short- and long-term tests which have been carried out at BAM on specimens made of representative types of elastomers, fluorocarbon rubber (FKM) and ethylene propylene diene rubber (EPDM). The investigation of the test results used to identify material models and their Parameters as well as the development of two finite element models for the numerical Simulation of tension and compression tests using the finite element code ABAQUS® are described. The calculation results are presented in comparison to the test results. The influence of important material and test parameters was investigated and discussed in sensitivity analyses.