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The first German package design approval certificate for a dual purpose cask intended for loading with damaged spent nuclear fuel was issued recently. BAM as part of the competent authority system in Germany carried out a comprehensive assessment procedure with respect to the mechanical and thermal design, the release of radioactive material and the quality assurance aspects of manufacturing and operation. Packages for the transport and storage of radioactive material have been assessed by BAM for many years, thus the common assessment procedure is well-known and good practice. Up to now only SNF without defects or HLW with well-defined properties were designated for long-term Interim storage and transports afterwards. Due to Germany’s nuclear phase out all other kinds of spent nuclear fuel in particular damaged spent nuclear fuel shall be packed as well. Damaged spent nuclear fuel needs a tight closure with Special encapsulations and clearly defined properties in Germany. In addition, these encapsulations shall be long-term durable, because they are not accessible after loading in a packaging within periodical inspections. The main difference to Standard package components is that encapsulations with a permanent closure achieve their specified conditions not after manufacturing but only during operation, after loading and closing. To ensure compliance with the specific conditions, special measures for quality assurance are necessary during operation of each encapsulation, e.g. drying and sealing, which were assessed by BAM. The present paper gives an overview of the conducted assessment from BAM and point out the findings concerning to the special closure lid of the approved encapsulation, which is screwed and welded. A wide verification concept is necessary to show the specific tightness under transport conditions. Together with quality assurance measures during first operation steps these encapsulations with damaged spent nuclear fuel can be handled like standard fuel assemblies in approved package designs.
Experimental and numerical investigation of prestressed bolt connections under lateral displacements
(2022)
The containment system of transport packages for spent nuclear fuel and high-level waste usually includes bolted lids with metal gaskets. The packages are assessed to specific transport conditions which are specified in the IAEA safety standards SSR-6 (IAEA 2018). These transport conditions, especially the so-called accident conditions of transport, imply high dynamic loading on the lids and the bolt connections of the package. The response of the lid systems on the mechanical accident conditions is generally investigated by experimental drop tests or numerically, e.g., by finite element analyses. The interpretation of the drop test results for the verification of the numerical models is often not obvious due to the complex superposition of different effects in the real tests. BAM has started a research project to get a better understanding about the behavior of prestressed bolt connections under loadings typical for these drop tests. In this context an experimental test set-up was developed to investigate the response of a single bolt connection under a prescribed lateral displacement of clamped parts. The bolt is instrumented by strain gauges to get the pretensional, the torsional and the bending stress in the bolt shank. Furthermore, the lateral movement and the tilt of the bolt head is measured during the test. A finite element model of the test set-up has been created in Abaqus FEA (Simulia 2021). The very detailed instrumentation of the test set-up shall give the opportunity to investigate and validate the numerical model. The aim of this paper is to give an overview about the proposed research project and to present first results.
A Memorandum of Understanding (MOU) between Argonne National Laboratory (Argonne) and the German Bundesanstalt für Materialforschung und -prüfung (BAM) was signed in October 2014. Its objectives are to promote cooperation among scientists and specialists at Argonne and BAM and establish a framework for collaboration in advanced technologies associated with the back end of the nuclear fuel cycle. Collaborative activities involving Argonne and BAM may be implemented through the promotion of joint research activities and scientific workshops and conferences; exchange of technical information; and visits by scientists, specialists, and graduate, postgraduate, and Ph.D. students. The MOU was renewed in January 2020 for another five years. Highlights of the progress and achievements are provided in identified topical areas for collaboration on ageing management guidance, storage, transportation and disposal R&D, joint conference activities, and conclude with the benefits of the MOU in fostering Argonne and BAM collaboration.
A Memorandum of Understanding (MOU) between Argonne National Laboratory (Argonne) and the German Bundesanstalt für Materialforschung und -prüfung (BAM) was signed in October 2014. Its objectives are to promote cooperation among scientists and specialists at Argonne and BAM and establish a framework for collaboration in advanced technologies associated with the back end of the nuclear fuel cycle. Collaborative activities involving Argonne and BAM may be implemented through the promotion of joint research activities and scientific workshops and conferences; exchange of technical information; and visits by scientists, specialists, and graduate, postgraduate, and Ph.D. students. The MOU was renewed in January 2020 for another five years. Highlights of the progress and achievements are provided in identified topical areas for collaboration on ageing management guidance, storage, transportation and disposal R&D, joint conference activities, and conclude with the benefits of the MOU in fostering Argonne and BAM collaboration.
BAM is the German Federal Institute for Materials Research and Testing and the competent authority for mechanical and thermal safety assessment of transport packages for spent fuel and high level waste. In context with safety assessment of RAM packages BAM performed numerous drop tests in the last decades. The tests were mostly accompanied by extensive and various measurement techniques especially by instrumented measurements with strain gages and accelerometers.
The procedure of drop testing and the resulting measurement analysis are the main methods to evaluate the safety against mechanical test conditions. Measurement techniques are dedicated to answer questions in regard to the structural integrity of a RAM package, the mechanical behavior of the prototype as well as of its content under impact conditions.
Test results like deceleration-time functions constitute a main basis for the validation of assumptions in the safety analysis and for the evaluation of numerical calculations. In this context the adequate selection of accelerometers and measurement systems for the performance of drop tests is important. Therefore it is not only necessary to find suitable positions for the accelerometers at the test specimens, but also to consider technical boundary conditions as e.g. temperature.
BAM is the German Federal Institute for Materials Research and Testing and the competent authority for mechanical and thermal safety assessment of transport packages for spent fuel and high level waste. In context with safety assessment of RAM packages BAM performed numerous drop tests in the last decades. The tests were mostly accompanied by extensive and various measurement techniques especially by instrumented measurements with strain gages and accelerometers.
The procedure of drop testing and the resulting measurement analysis are the main methods to evaluate the safety against mechanical test conditions. Measurement techniques are dedicated to answer questions in regard to the structural integrity of a RAM package, the mechanical behaviour of the prototype as well as of its content under impact conditions.
Test results like deceleration-time functions constitute a main basis for the validation of assumptions in the safety analysis and for the evaluation of numerical calculations. In this context the adequate selection of accelerometers and measurement systems for the performance of drop tests is important. Therefore it is not only necessary to find suitable positions for the accelerometers at the test specimens, but also to consider technical boundary conditions as e.g. temperature. Accelerometers are widely used for the measuring of motion i.e. velocity or the displacement of the rigid cask body, vibration and shock events.
Acceleration measurements as well as their analysis are often very complex and extensive also because they are in turn embedded in complex drop test experiments having to consider difficult boundary conditions as for example very low specimen temperatures, large drop heights and sophisticated drop orientations of the specimen. In every case special instruments and adequate technical equipment is required to accelerations under these and transient shock conditions which are characterized in our case by impact times in the range of a few milliseconds up to perhaps 100 Milliseconds naturally depending on container design and drop test conditions as drop height and target.
The paper gives an overview of drop tests under kinematic aspects performed with RAM packages. Furthermore, experimental advancements of accelerometer instrumentation within drop testing, e.g. the characteristics and possibilities of accelerometers, behavior of accelerometers and various influence factors are shown.
Fire Influence to Wood Filled Impact Limiters - Implications for the Package Design Safety Case
(2023)
Impact limiters with wooden components are widely used in the design of packages for transportation of radioactive material. In most designs, the wood is encapsulated with steel sheets. Impact limiters mainly determine the mechanical and thermal behaviour of the package in accident conditions of transport in accordance with the IAEA Regulations.
In context with research and development for package design approval competence, the thermal behaviour of heavy-weight packages was investigated at BAM with an artificially pre-damaged generic impact limiter design. Within this first investigation, the pre-damaged impact limiter with a diameter of 2.3 meters was mounted on a water tank simulating the thermal capacity of a cask during the fire test. The water tank is part of a water circulating system built of several components such as pump, heater, cooler, sliding valve, flow meter, thermocouples and control unit in order to measure the heat flux.
Furthermore, the investigations focus on the effects this additional heat generation would have on the cask and especially on the lid-closure system with the gasket.
The results of these experiments could find consideration in the safety case of the transport packages of radioactive material using wood filled impact limiters.
BAM is the German Federal Institute for Materials Research and Testing and the competent authority for mechanical and thermal safety assessment of transport packages for spent fuel and high level waste. In context with safety assessment of RAM packages BAM performed numerous drop tests in the last decades. The tests were mostly accompanied by extensive and various measurement techniques especially by instrumented measurements with strain gages and accelerometers.
The procedure of drop testing and the resulting measurement analysis are the main methods to evaluate the safety against mechanical test conditions. Measurement techniques are dedicated to answer questions in regard to the structural integrity of a RAM package, the mechanical behavior of the prototype as well as of its content under impact conditions.
Test results like deceleration-time functions constitute a main basis for the validation of assumptions in the safety analysis and for the evaluation of numerical calculations. In this context the adequate selection of accelerometers and measurement systems for the performance of drop tests is important. Therefore it is not only necessary to find suitable positions for the accelerometers at the test specimens, but also to consider technical boundary conditions as e.g. temperature.
Fire testing is an essential part of the hypothetical, cumulative mechanical and thermal test conditions that shall guarantee package safety in severe accidents. Within regulatory approval of transport or storage packages for radioactive material, specific thermal load tests are required in accordance to licensing conditions and international standards, respectively. The specifications of these thermal tests are based on test conditions with equivalent heat input to that of a hydrocarbon fuel fire. In the past, light heating oil, diesel or kerosene was mostly used as the fuel to generate the pool fire. In accordance with IAEA regulations for a fire in an accident, the temperature of 800 °C over a period of 30 minutes must be fulfilled. Furthermore, the delivery acceptance criteria for containers in nuclear waste repositories could reach for example average temperatures of 800 °C during a period of one hour in combination with defined requirements on activity release. BAM as a scientific and technical German federal government institute operates an open air Technical Safety Test Site for experimental investigations of dangerous good and its containment. In this areal a large fire test facility is under operation. Liquid Propane is utilized as fuel which is pumped via pipelines from a central storage tank to the fire exposed test facility areas. In the ring burner system, the gas is released from nozzles, and ignited by ignition burners. The paper includes examples of fire test performance with prototypes of a transport package and a storage container, respectively. In preparation of the thermal load, calorimeter tests have been performed using test specimens of appropriate size and behavior. For the fire test scenario is demonstrated that the IAEA thermal test requirements are fulfilled.
Fire testing is an essential part of the hypothetical, cumulative mechanical and thermal test conditions that shall guarantee package safety in severe accidents. Within regulatory approval of transport or storage packages for radioactive material, specific thermal load tests are required in accordance to licensing conditions and international standards, respectively. The specifications of these thermal tests are based on test conditions with equivalent heat input to that of a hydrocarbon fuel fire. In the past, light heating oil, diesel or kerosene was mostly used as the fuel to generate the pool fire. In accordance with IAEA regulations for a fire in an accident, the temperature of 800 °C over a period of 30 minutes must be fulfilled. Furthermore, the delivery acceptance criteria for containers in nuclear waste repositories could reach for example average temperatures of 800 °C during a period of one hour in combination with defined requirements on activity release. BAM as a scientific and technical German federal government institute operates an open air Technical Safety Test Site for experimental investigations of dangerous good and its containment. In this areal a large fire test facility is under operation. Liquid Propane is utilized as fuel which is pumped via pipelines from a central storage tank to the fire exposed test facility areas. In the ring burner system, the gas is released from nozzles, and ignited by ignition burners. The paper includes examples of fire test performance with prototypes of a transport package and a storage container, respectively. In preparation of the thermal load, calorimeter tests have been performed using test specimens of appropriate size and behavior. For the fire test scenario is demonstrated that the IAEA thermal test requirements are fulfilled.