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Dive into the research topics where Holger Völzke is active.

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Featured researches published by Holger Völzke.


Packaging, Transport, Storage and Security of Radioactive Material | 2014

Long term performance of metal seals for transport and storage casks

Holger Völzke; Dietmar Wolff; Ulrich Probst; Sven Nagelschmidt; Sebastian Schulz

Abstract 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.


Packaging, Transport, Storage and Security of Radioactive Material | 2004

SAFETY ANALYSIS OF CASKS UNDER EXTREME IMPACT CONDITIONS

Günter Wieser; Linan Qiao; Holger Völzke; Dietmar Wolff; Bernhard Droste

Abstract The determination of the inherent safety of casks under extreme impact conditions has been of increasing interest since the terrorist attacks of 11 September 2001. For nearly three decades BAM has been investigating cask safety under severe accident conditionslike drop tests from more than 9 m onto different targets and without impact limiters as well as artificially damaged prototype casks. One of the most critical scenarios for a cask is the centric impact of a dynamic load onto the lid-seal system. This can be caused, for example, by a direct aircraft crash (or just its engine) as well as by an impact due to thecollapse of a building, e.g. a nuclear facility storage hall. In this context BAM is developing methods to calculate the deformation of cask components and — with respect to leak-tightness — relative displacements between the metallic seals and their counterparts. This paper presents reflections on modelling of cask structures for finite-element analyses and discusses calculated results of stresses and deformations. Another important aspect is the behaviour of a cask under a lateral impact by aircraft or fragments of a building. Examples of the kinetic reaction (cask acceleration due to the fragments, subsequent contact with neighbouring structures like the ground, buildings or casks) are shown and discussed in correlation to cask stresses which are to be expected.


Packaging, Transport, Storage and Security of Radioactive Material | 2011

Aging management for long-term interim storage casks

Anton Erhard; Holger Völzke; Ulrich Probst; Dietmar Wolff

Abstract The aging management system for the mechanical components of nuclear power plants (NPPs) must be established and used by the licensee in such a way that the quality of safety relevant components is guaranteed for the completely designed lifetime of the NPP. This demands an extensive plant life management with special emphases on the knowledge of the degradation in material properties. The basic safety concept in Germany observes this circumstance. Lifetime extension of the German NPPs is an aim of the current valid coalition agreement of the German government. Operational extension of interim storage facilities requires, in comparison to the aging management system for NPP, an aging management system adapted to the special circumstances of spent fuel storage casks. Extension of interim storage periods for spent fuel casks beyond the designed lifetime requires, in comparison to the components of an NPP, an increasing knowledge of material degradation with potential impact on cask integrity, e.g. leak tightness. Dry interim storage in Germany has been approved for 40 years. After that time, according to the present strategy, a final repository should be available. However, until now, such a final facility still does not exist, and the German exploration and licensing process is heavily delayed. Currently, discussions are continuing regarding further exploration of the Gorleben salt mine. There is willingness to overcome this situation that is clearly described in the available coalition agreement of the federal government. Anyway, however, the prediction is viewed; a repository for heat generating radioactive waste in Germany will not be available in the near future and may not be available when first storage facilities and casks reach their 40 years of approved lifetime, which will occur in ∼25 years starting from now. Therefore, the question must be asked: what has to be done with the existing storage casks in the interim facilities? May these casks be fit for continued use, with an extension of the storage period? One option is to have an aging management system, which creates enough information about the technical condition of safety relevant cask properties. This is the basis for safety evaluation for extended storage periods. In the present paper, possible aging mechanisms for high level waste storage casks are discussed, as well as the influence of the time dependent changes of the component properties.


Packaging, Transport, Storage and Security of Radioactive Material | 2008

Topical BAM cask design evaluation using drop tests and numerical calculations: accidental cask drop without impact limiters onto storage building foundation

Holger Völzke; Linan Qiao; Uwe Zencker; Dietmar Wolff; Karl Feutlinske; André Musolff

Abstract Cask impacts without impact limiters onto unyielding targets result in totally different mechanical reactions from those of relatively smooth impacts using impact limiters. During the licensing procedure of the new GNS CASTOR HAW 28M design for vitrified high activity waste, BAM therefore decided to perform an additional drop test with a 1 : 2 scale test cask (CASTOR HAW/TB2). In spite of a small drop height of only 0˙3 m onto the unyielding target of the BAM drop test facility, which conservatively covers any storage building foundation, the impact caused considerable stresses to the cask structure with high stress and strain rates. This paper presents the evaluation strategy of BAM including the drop test results and the development and qualification of appropriate finite element modelling to achieve sufficient agreement between test and calculation results. Further steps include mechanical analyses of reduced and full scale cask designs to determine the most critically stressed areas of the structure, verify scaling factors and demonstrate safety with respect to cask integrity and tightness.


Packaging, Transport, Storage and Security of Radioactive Material | 2004

THERMOMECHANICAL FINITE-ELEMENT ANALYSES OF BOLTED CASK LID STRUCTURES

Günter Wieser; Linan Qiao; Arno Eberle; Holger Völzke

Abstract Analysis of complex bolted cask lid structures under mechanical or thermal accident conditions is important for the evaluation of cask integrity and leak tightness in package design assessment according to the transport regulations or in aircraft crash scenarios. In this context BAM is developing methods based on finite elements (FE) to calculate the effects of mechanical impacts onto the bolted lid structures as well as effects caused by severe fire scenarios. In the case of fire it might not be enough to perform only a thermal heat transfer analysis. A complex cask design together with a severe hypothetical time–temperature curve representing an accident fire scenario will create a strong transient heating up of the cask body and its lid system. This causes relative displacements between the seals and their counterparts that can be analysed by a so-called thermomechanical calculation. Although it is currently not possible to directly correlate leakage rates with results from deformation analyses, an appropriate finite element model of the considered type of metallic lid seal has been developed. For the present it is possible to estimate the behaviour of the seal based on the calculated relative displacements at its seating and the behaviour of the lid bolts under the impact load or the temperature field, respectively. Except for the lid bolts, the geometry of the cask and the mechanical loading is axisymmetric which simplifies the analysis considerably, and a two-dimensional finite-element model with substitute lid bolts may be used. The substitute bolts are modelled as one-dimensional truss or beam elements. An advanced two-dimensional bolt submodel represents the bolts with plane stress continuum elements. This paper discusses the influence of different bolt modellings on the relative displacements at the seating of the seals. The influence of bolt modelling, thermal properties and the detailed geometry of the two-dimensional finite-element models on the results are discussed.


Wood Science and Technology | 2013

Dynamic crushing characteristics of spruce wood under large deformations

Germar Eisenacher; Robert Scheidemann; Martin Neumann; Bernhard Droste; Holger Völzke

An extensive series of large deformation crushing tests with spruce wood specimens was conducted. Material orientation, lateral constraint and loading rate were varied. Regarding material orientation, a reduction in the softening effect and the general force level was observed with a higher fiber-load angle. A comparison with characteristics gained by application of Hankinson’s formula showed discrepancies in compression strength and the beginning of the hardening effect. Lateral constraint of the specimens caused a multiaxial stress state in the specimens, which was quantified with the applied measuring method. Further, a higher force level compared to specimens without lateral constraint and significant hardening effect at large deformations resulted. Thus, the influence of a multiaxial stress state on the force level could be determined. An increase in the loading rate led to higher force levels at any displacement value and material orientation.


Packaging, Transport, Storage and Security of Radioactive Material | 2008

Investigation of seal effects according to axial compression variation of metal seals for transport and storage casks

Ulrich Probst; Peter Hagenow; Holger Völzke; Dietmar Wolff; Peter Wossidlo; Behboud Abbasi; Andreas Achelpöhler-Schulte; Sebastian Schulz

Abstract Casks for the transport and storage of heat generating radioactive waste in Germany are normally provided with screwed lid systems, which are in most cases equipped with double jacket metal seals with an inner spring wire to provide long term resistance to the seal compression force. Preservation of the high sealing quality of those seals under operational and accidental stress conditions is essentially important to the safety of those casks. Relative displacements of the lid system surfaces caused by specific impact scenarios cannot be excluded and have to be evaluated with respect to a possible increase in the leakage rate. To get representative data for such metal sealed lid systems, BAM has developed a special conceptualised flange system placed in an appropriate testing machine for relevant mechanical loading of the metal seals under static and cyclic conditions. Furthermore, the flange system enables continuous measurement of the standard helium leakage rate during each test. The primary aim of the investigation is to identify the correlation between variation of installation conditions (axial displacements) caused by external loads and the standard helium leakage rate. An essential parameter in this case is the useable resilience ru of a metal seal under relevant stress conditions. The useable resilience ru is the vertical difference in the cross-section between the seals assembling status and the point where the leakage rate, by means of external load relieving, exceeds the quality criterion of 10–8 Pa m3 s–1. Load relieving can instantly occur due to modification of the seal groove dimension caused by accident impacts and deformation of the lid system. Furthermore, component specific basis data for the development of finite element calculation models should be collected. In the tests, seals are subjected to static and cyclic loads. All tests are performed at ambient temperature. This paper presents the test configuration, different test series and results of the current experiments. Typical load–displacement–leakage rate correlations are presented and discussed.


Nuclear Engineering and Design | 1994

Analytical, numerical and experimental investigations on the impact behaviour of selected structures

T. Quercetti; G. Wieser; Holger Völzke; P. Zeisler

Abstract In the context of approval design tests of packages for transport and storage of radioactive materials, there is an evident trend to numerical simulation with the finite element method. However, it remains a difficult issue to obtain verification of the calculation results through experimental investigations such as the drop test with simple geometric structures up to complete packages. Drop tests of simple geometric structures are used in this investigation in order to obtain statements concerning possibilities for numerical simulation. In the following the test and calculation results of a roundsteel impact will be presented in the context of verification of calculations by experiment and the safety assurance of packages.


Volume 1: Low/Intermediate-Level Radioactive Waste Management; Spent Fuel, Fissile Material, Transuranic and High-Level Radioactive Waste Management | 2013

Safety Aspects of Dry Spent Fuel Storage and Spent Fuel Management

Wolfgang Botsch; Silva Smalian; Peter Hinterding; Holger Völzke; Dietmar Wolff; Eva-Maria Kasparek

As with the storage of all radioactive materials, the storage of spent nuclear fuel (SF) and high-level radioactive waste (HLW) must conform to safety requirements. Safety aspects like safe enclosure of radioactive materials, safe removal of decay heat, nuclear criticality safety and avoidance of unnecessary radiation exposure must be achieved throughout the storage period. The implementation of these safety requirements can be achieved by dry storage of SF and HLW in casks as well as in other systems such as dry vault storage systems or spent fuel pools, where the latter is neither a dry nor a passive system. After the events of Fukushima, the advantages of passively and inherently safe dry storage systems have become more obvious. TUV and BAM, who work as independent experts for the competent authorities, present the licensing process for sites and casks and inform about spent nuclear fuel management and issues concerning dry storage of spent nuclear fuel, based on their long experience in these fields. All safety relevant issues like safe enclosure, shielding, removal of the decay heat or behavior of cask and building under accident conditions are checked and validated with state-of-the-art methods and computer codes before the license approval. It is shown how dry storage systems can ensure the compliance with the mentioned safety criteria over a long storage period. Exemplarily, the process of licensing, erection and operation of selected German dry storage facilities is presented.Copyright


Archive | 2018

Basic of Transport and Storage of Radioactive Materials

Holger Völzke; Thomas Quercetti; Viktor Ballheimer; Marko Nehrig; Dietmar Wolff; Frank Wille

Transport and storage of radioactive materials are performed in countries with policy of either closed or open nuclear fuel cycle. The related technologies have been established by accumulation of experiences and researches including demonstrative tests using full scale or scale models and analyses. Those are essential before commercialization, but are often costly and time consuming. Such demonstrative works should not be repeated meaninglessly, but can be shared through this kind of book and used by readers and the future generations to advance the technology effectively. This book systematically provides findings from lots of valuable researches on safety of transport and storage of radioactive materials under normal and accident conditions that have an impact on basis of safe regulations, designs, and operations.

Collaboration


Dive into the Holger Völzke's collaboration.

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Dietmar Wolff

Bundesanstalt für Materialforschung und -prüfung

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Uwe Zencker

Bundesanstalt für Materialforschung und -prüfung

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Ulrich Probst

Bundesanstalt für Materialforschung und -prüfung

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Bernhard Droste

Bundesanstalt für Materialforschung und -prüfung

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Linan Qiao

Bundesanstalt für Materialforschung und -prüfung

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Matthias Jaunich

Bundesanstalt für Materialforschung und -prüfung

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Eva-Maria Kasparek

Bundesanstalt für Materialforschung und -prüfung

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Frank Wille

Bundesanstalt für Materialforschung und -prüfung

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Mike Weber

Bundesanstalt für Materialforschung und -prüfung

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Peter Hagenow

Bundesanstalt für Materialforschung und -prüfung

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