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FZD-471

Environment and Safety

TRIENNIAL SCIENTIFIC REPORT 2004 -2007 I Volume 2

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PREFACE

FOCUS

FACILITIES FOR EUROPE

Free-Electron Laser at ELBE

The Rossendorf Beamline (ROBL) at ESRF

TOPFLOW thermal hydraulic test facility

RESEARCH

Thermal fluid dynamics: Two-phase flow - experiment and simulation

DYN3D - advanced reactor simulations in 3D

Magnetic flow control in metal casting and crystal growth

Cosmic magnetism in the lab

The reactor pressure vessel - a strong barrier to retain corium

How reactor pressure vessels grow old

Design of a photo-neutron source for time-of-flight measurements at the Radiation Source ELBE

Bacteria and nuclear waste disposal

Self-organizing surface layer proteins as building blocks for innovative nanomaterials

How mineral surfaces retard uranium migration

Environmental impact of depleted uranium

XAFS investigation of actinide species under controlled redox conditions

FACTS & FIGURES

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Content

Cover picture: The picture shows the result of a Computational Fluid Dynamic (ANSYS CFX®)calculation on the mixing of a de-borated slug of coolant (indicated in green) with the ambientcoolant (indicated in red) in the reactor pressure vessel of a pressurized water reactor. The lessdense slug stratifies in the upper part of the cold leg and flows around the core barrel in thetop region of the downcomer. Mixing takes place on the way downwards to the core andmitigates the reactivity inserted.Photo left: Rainer Weisflog

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Preface

This volume of the Triennial Scientific Report highlights the scientific output of the FZDresearch program “Environment and Safety”, covering the years 2004 to 2006 and thefirst six months of 2007. It is one out of three volumes that are published this year for thefirst time. The first part of this report introduces the “Environment and Safety” programas well as the large-scale facilities that are used for research within this program. Thesecond part consists of twelve articles on research projects that were conducted byscientists of the Institute of Safety Research and the Institute of Radiochemistry.

The last eighteen months were characterized by an intense discussion about the future ofthe Forschungszentrum Dresden-Rossendorf (FZD). In meetings and seminars we debatedabout our topical status and our future, asking questions like: “What are our futurescientific objectives?” “Which research methods and facilities are required in order toreach those goals?” “How can new research activities be funded and who are our futurecooperation partners?”

The Institute of Safety Research of the FZD is represented in many important EuropeanNetworks and Integrated Research Projects, e.g. in the Sustainable Nuclear EnergyTechnology Platform which was launched in Brussels in September 2007. This platformaims at bringing together researchers and industry to define and implement a strategicresearch agenda and a corresponding deployment strategy. For the Environment andSafety program collaboration partners from scientific institutions and from Europeanindustry are of utmost importance. Just recently, the Institute of Safety Research andAREVA-NP Erlangen have signed an agreement on joint research projects. Workshopsabout the simulation of multi-phase flows have taken place in Dresden regularly,organized by the FZD together with ANSYS Germany GmbH. The TOPFLOW facility ofthe FZD is constructed especially for complex multi-phase flow experiments. The resultsof these experiments have been transferred into so called CFD (Computational FluidDynamics) codes like CFX® developed by ANSYS. Moreover, European industry makes useof the TOPFLOW facility for experiments regarding the safety of nuclear power plants.

Research on actinides, like uranium, plays the central role at the Institute of Radio-chemistry of the Forschungszentrum Dresden-Rossendorf. As only few groups in Europework on this special field of chemistry, close collaboration with the small scientificcommunity is essential, in particular because radioecology addresses problems ofimmediate importance for society. Transport mechanisms of actinides affect questionswhich must be solved on the European level, e.g. the final disposal of waste from nuclearpower plants. Naturally, the same is true for research on the safety of nuclear powerplants.

Roland Sauerbrey I Scientific Director

PREFACE

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Prof. Dr. Roland Sauerbrey

The Rossendorf Beamline at the European Synchrotron Radiation Facility (ESRF) inGrenoble/France has proved to be an attractive experimental site for radiochemists fromall over the world, because for many years it was the only synchrotron beamline whereradioactive samples could be handled. The Rossendorf Beamline has guaranteed fruitfulcollaboration projects with many well-known European research institutions, partlyfinanced by the European Union. For example, the Institute of Radiochemistry is activelyengaged in the European ACTINET Network, where the training of young scientists is ofspecial relevance. Furthermore, new cooperation projects with Japanese institutions likethe University of Tokyo have started within the last few months.

Two prestigious prizes were awarded to FZD scientists of the Environment and Safetyprogram recently: Prof. Gert Bernhard, Dr. Gerhard Geipel and Dr. Samer Amayri receivedthe Kurt Schwabe Prize of the Saxon Academy of Sciences in 2005 for their discovery of anew uranium complex in mining water. Dr. Hans-Georg Willschütz was awarded the KarlWirtz Prize 2007 of the Nuclear Technology Association (Kerntechnische Gesellschaft) forhis research on the behavior of the reactor pressure vessel under severe accidentconditions.

Finally, I would like to thank our partners in both the state and the federal government fortheir continued support, our national and international scientific cooperation partners formany successful joint research endeavors and, last but not least, the entire staff of theFZD for their dedicated work for this fine institution.

Environment and Safety program at the Forschungszentrum Dresden-Rossendorf

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Gert Bernhard, Frank-Peter Weiss

This program is dedicated to the protectionof humanity and the environment againstindustrial risks. For this purpose, ourresearch aims at assessing and enhancingthe safety of industrial plants and im-proving the efficiency and sustainability ofthe processes involved. Results from ourresearch are applied to nuclear facilities of current and future designs as well as to installations in the process industries.It is the particular goal to assess andminimize the risks related to the nuclearfuel cycle. This includes the relics of former

uranium mining, the power generation innuclear reactors, and the final geologicaldisposal of the radioactive waste. Many ofthe scientific methods and tools used innuclear engineering can be successfullyadapted to non-nuclear fields, for exampleto optimize industrial processes bycustomized flow control.

The Environment and Safety program isimplemented by the Institute of Radio-chemistry and the Institute of SafetyResearch. It includes the program areasRadioecology, Plant and Reactor Safety,and Thermal Fluid Dynamics. Whereas the

Radioecology program area focuses on theidentification of the chemical interactionand the mobility of radionuclides,especially of actinides, in the geo- and the bio-spheres, our engagement in thePlant and Reactor Safety program area isdirected towards the development ofphysical models used for accident analysisand the description of irradiation-inducedageing phenomena in reactor constructionmaterials. Complementing this, theThermal Fluid Dynamics program areastudies transient multi-phase flows andmagneto-hydrodynamic (MHD)phenomena to provide the basis for

Photo: Rainer Weisflog

advanced reactor simulation and optimization in process engineering, chemical industry,crystal growth, and metallurgy. The development and validation of tools for processsimulation, accident analysis, and long-term safety assessment of the geological disposalof radioactive waste, with the emphasis on thermo- and fluid dynamic computationmethods, constitute the framework for these program areas.

The research program is based on large-scale experimental user facilities operated by theFZD such as the Radiation Source ELBE, the Rossendorf X-ray beamline ROBL at the ESRFin Grenoble, and the Transient Two-Phase Flow Test Facility (TOPFLOW). Beyond that,close collaborations exist with the other research programs of the FZD, which are devotedto the Structure of Matter and to Life Sciences. These collaborations are for examplerelated to the design of the pulsed photo-neutron source at ELBE and to the developmentof biological metal templates with modified magnetic properties for the Dresden HighMagnetic Field Laboratory (HLD). In the fields of irradiation-induced materials ageing andsurface layer characterization, we considerably benefit from the expertise at the Instituteof Ion Beam Physics and Materials Research. Moreover, we contribute to the develop-ment of new macromolecules for nuclear medicine by our competence in laserspectroscopy.

The reactor safety and radioecology research is integrated in the German Alliances for Competence in Nuclear Technology (Kompetenzverbund Kerntechnik) and forCompetence in Radiation Research (Kompetenzverbund Strahlenforschung), respectively.The magneto-hydrodynamic (MHD) project of the Institute of Safety Research forms amajor part of the Collaborative Research Center (SFB) 609 funded by the GermanResearch Foundation (DFG). In this SFB, the FZD closely collaborates with the TechnischeUniversität Dresden and, for example, with the TU Bergakademie Freiberg on funda-mental and applied MHD problems.

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FOCUS

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Laser beam in a glove box.

Facilities for Europe

Free-Electron Laser at ELBE

Harald Foerstendorf, Karsten Heim,Wolfgang Seidel, Gert Bernhard

The migration behavior of radioactiveheavy metal ions in groundwater aquifersis essentially determined by theirinteractions with mineral surfaces. Theidentification of the molecular speciesparticipating in the complex physico-chemical processes at the interfaces is a challenging task for modern actinideresearch.

Laser spectroscopic techniques have shown to be valuable tools for analyzingadsorbates on surfaces and for investi-gating the molecular processes occurring at the interfaces [1]. Particularly from theadoption of tunable infrared laser systems,

a combination of surface selectivity andvibrational spectroscopic information canbe expected [2]. Today, the most brilliantlight sources for infrared light areaccelerator-based light sources such asfree-electron lasers (FEL). These lasersmeet all the requirements for vibrationalspectroscopic surface analyses due to theirhigh spectral intensity, directionality, highdegree of polarization, and coherence. Thetime structure of the pulsed light and thetunability over a broad wavelength rangeof interest complete the outstandingproperties of this class of lasers.

At the FEL facility FELBE, an optical userlaboratory is equipped for spectroscopicinvestigations of samples containingcertain radioactive isotopes, obeying all

aspects of radiation protection. As far aswe know, this is unique for an FEL facility.The laboratory permits the application ofadvanced infrared spectroscopic tech-niques in actinide research [3]. A glove boxprovides the possibility to perform laserspectroscopic experiments on sensitivesamples which have to be kept in an inertgas atmosphere excluding oxygen andcarbon dioxide.

The experimental work focuses onvibrational spectroscopic investigations of actinide molecule complexes in solidsamples using photothermal beamdeflection spectroscopy. This techniquecombines the low detection limits ofphotothermal methods, vibrationalspectroscopic information of the sample

FACILITIES FOR EUROPE

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under investigation [4], and surface selectivity [5]. Initial results of model samplescontaining low concentrations of actinide molecule complexes (UO2

2+, NpO2+) were

obtained by photothermal beam deflection [3].

Another experimental approach, which is substantially funded by the European Union and constitutes a joint research project with the Forschungszentrum Karlsruhe and theParis National Institution of Higher Learning in Chemistry (ENSCP), uses the high intensityof infrared radiation to generate non-linear optical processes such as sum frequencygeneration to elucidate molecular structures occurring at well-defined interfaces in anaqueous medium [2]. The spectral information from the interfaces obtained by sumfrequency generation is highly site-selective since neither in the bulk nor in nearly allcrystal materials is a signal generated. Therefore, adopting a tunable FEL allows theacquisition of infrared spectra of radioisotope ions asorbed to a functional surface species.From these, spectra molecular structures of the surface complexes can be derived.

References[1] Optical second harmonic spectroscopy of semiconductor surfaces: advances in microscopic

understanding, M.C. Downer, B.S. Mendoza, V.I. Gavrilenko, Surface and Interface Analysis 31, 966 – 986 (2001)

[2] Molecular bonding and interactions at aqueous surfaces as probed by vibrational sum frequency spectroscopy, G.L. Richmond, Chemical Reviews 102, 2693 – 2724 (2002)

[3] Identification of actinide molecule complexes: A new vibrational spectroscopic approach at the free-electron laser facility FELBE, H. Foerstendorf, K. Heim, W. Seidel, G. Bernhard, Journal of Nuclear Materials 366, 248 – 255 (2007)

[4] Infrared characterization of environmental samples by pulsed photothermal spectroscopy,W. Seidel, H. Foerstendorf, K.H. Heise, R. Nicolai, A. Schamlott, J.M. Ortega, F. Glotin, R. Prazeres, European Physical Journal – Applied Physics 25, 39 – 43 (2004)

[5] Diffusion waves and their uses, A. Mandelis, Physics Today 53, 29 – 34 (2000)

Scheme of the radiochemistry laboratory in the ELBE building.

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Andreas C. Scheinost

Synchrotrons provide extremely brilliantelectromagnetic radiation across a widerange of energy, covering the infrared,visible, UV, and X-ray regions, which maybe used for a large variety of spectroscopicand scattering techniques. Especially thehard X-rays with a small wavelength andhigh penetration depth provide versatiletools to probe physical and chemical statesof matter in an almost unlimited variety of samples, from aqueous solutions andbiological tissue to metal nanoclusters andthin films. The Rossendorf Beamline withits two experimental stations (Radio-chemistry, Materials Research), built andoperated by the FZD since 1998 is locatedat the most powerful synchrotron inEurope, the European SynchrotronRadiation Facility (ESRF).

The Radiochemistry station enables X-rayAbsorption Spectroscopy (XAS) of dilutesystems. Special safety systems allow safelymeasuring alpha-emitting radionuclides. At this unique facility, supported by theInstitute of Radiochemistry, research iscarried out on the identification, structuralcharacterization, and quantification ofactinides (Th, Pa, U, Np, Pu, Am, Cm) and other radionuclides species (e.g., Tc,

Zn, Se). Equipped with a 13-elementgermanium detector with digital electronicsand a closed-cycle helium cryostat, thisstation is well-adapted to measureenvironmental samples at concentrationsas low as 10 ppm. This basic researchcontributes to a better understanding ofthe biogeochemistry of radionuclides andimproved environmental risk assessmentsas well as the development of remediationstrategies for contaminated sites.

As a user facility, ROBL provides one thirdof its beamtime to the European researchcommunity via a proposal-based selectionsystem managed by the ESRF. The rest of the beamtime is provided to FZD re-searchers and collaborating partners.

The unique experimental facilities of ROBLare highly in demand by FZD and otherresearch teams, including institutions likeMax Planck, the ETH Zurich, and AMD(Advanced Micro Devices). From 2000 to2002, ROBL was supported by theEuropean Union within the framework ofthe “Access to Research Infrastructures”program. Since 2004, it has been part ofthe “ACTINET-EU Network of Excellencefor Actinide Research”, providing itsresearch facilities to all European membercountries. ROBL beamtime is even sought

after by research teams from overseas:currently a research contract is establishedbetween a consortium led by the Uni-versity of Tokyo and the Japan AtomicEnergy Agency (JAEA) to open ROBL forthe Japanese Radiochemistry community.

To widen the experimental potential intothe micrometer regime, we are currentlyplanning a third station, where spectros-copy and diffraction will be implementedinto a scanning X-ray microscope.

The Rossendorf Beamline (ROBL) at ESRF

References[1] ROBL – a CRG beamline for radio-

chemistry and materials research at the ESRF, W. Matz, N. Schell, G. Bernhard, F. Prokert, T. Reich, J. Claussner, W. Oehme, R. Schlenk, S. Dienel, H. Funke, F. Eichhorn, M. Betzl, D. Prohl, U. Strauch, G. Huttig, H. Krug, W. Neumann, V. Brendler, P. Reichel, M.A. Denecke, H. Nitsche, Journal of Synchrotron Radiation 6, 1076 – 1085 (1999)

[2] The Rossendorf Beamline at the ESRF: An XAS experimental station for actinide research, A.C. Scheinost, in: Speciation, Techniques and Facilities for Radioactive Materials at Synchrotron Light Sources (NEA No. 6046), OECD, 2006, pp. 95 – 101

Udo Strauch preparing an experiment at ROBL.

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Uwe Hampel, Helmar Carl

The multi-purpose thermal hydraulic testfacility TOPFLOW (Transient Two PhaseFlow Test Facility) is a device that is uniquein the world for studying thermal hydraulicphenomena of steam-water two-phaseflows at high pressures and temperatures.TOPFLOW has a maximum heating powerof 4 MW and allows operation at pressuresup to 7 MPa and temperatures of up to286 °C in pipes and vessel geometriesrelevant to industry. One of its distinctivefeatures is the advanced two-phase flowinstrumentation, which includes high speedand IR cameras, wire-mesh sensors, phase-sensitive temperature sensors, and X-raytomography. Furthermore, there is a largepressure chamber that serves as apressurized laboratory for experiments incomplex flow domain geometries. It allowsoperating thermal hydraulic test rigs of upto 7 m length and 2 m height in pressureequilibrium which enables optical andinfrared flow observation through thinwalls or glass windows.

TOPFLOW is devoted to basic and applied research on two-phase flowphenomena, which play a key role in many industrial fields such as chemicalengineering (bubble columns, stirred

reactors, electrochemistry), mineral oilprocessing, and nuclear technology.Currently, we are using TOPFLOW toqualify computational fluid dynamics codes(CFD) for two-phase flow simulations.Here, TOPFLOW is employed to deriveappropriate closure laws for interfacialmomentum and heat and mass transferfrom experimental data.

TOPFLOW is the reference test facility of the German CFD Alliance on NuclearReactor Safety and is presently operated in the frame of two large projects. Onecomprehensive project is funded by theGerman Federal Ministry of Industry(BMWi). It deals with the provision of new experimental data for CFD codedevelopment and validation in reactorsafety analysis. This includes two-phasesteam-water flow in vertical pipes andhorizontal flow channels, as well as inmore complex geometries. The secondproject is concerned with the pressurizedthermal shock phenomenon, which is acrucial reactor safety issue for aged reactorpressure vessels during emergency corecooling in a loss-of-coolant scenario. Theproject is a collaboration of seven industrialand scientific partners: Commissariat àl’Energie Atomique (CEA) France,Electricité de France (EDF), AREVA NP

France, Institut de Radioprotection et de Sûreté Nucléaire (IRSN) France, PaulScherrer Institute (PSI) Switzerland, ETHZürich, Switzerland, and FZD. These twoprojects will completely occupy the ex-perimental capacity of TOPFLOW until the year 2011.

TOPFLOW thermal hydraulic test facility

References[1] Evolution of the structure of a gas-liquid

two-phase flow in a large vertical pipe, H.-M. Prasser, M. Beyer, H. Carl, S. Gregor,D. Lucas, H. Pietruske, P. Schütz, F.-P. Weiß, Nuclear Engineering and Design237, 1848 – 1861 (2007)

[2] The multipurpose thermalhydraulic test facility TOPFLOW: an overview on experimental capabilities, instrumentation and results, H.-M. Prasser, M. Beyer, H. Carl, A. Manera, H. Pietruske, P. Schütz,F.-P. Weiß, Kerntechnik 71, 163 – 173 (2006)

[3] Influence of the pipe diameter on the structure of the gas/liquid interface in a vertical two-phase pipe flow,H.-M. Prasser, M. Beyer, A. Böttger, H. Carl, D. Lucas, A. Schaffrath, P. Schütz, F.-P. Weiß, J. Zschau, Nuclear Technology 152, 3 – 22 (2005)

RESEARCH INSTITUTE OF SAFETY RESEARCH

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Dirk Lucas, Uwe Hampel, Horst-Michael Prasser*

Two-phase flows can be found in manyindustrial applications, as for example innuclear installations and chemical processindustries. They are characterized by acomplex structure of the interface betweenthe two phases. This structure of theinterface results from the momentumtransfer between the phases anddetermines heat and mass exchange. Atthe same time, the transfer through theinterface is responsible for the evolution of the structure of the flow. Therefore,design, optimization and safety analysesrequire reliable tools for predicting thecharacteristics of the two-phase flows. The computer codes currently used, forexample in the safety analysis of nuclearpower reactors, are one-dimensional andbased on empirical correlations valid onlyfor special geometries, scales, and fullydeveloped flows.

Computational Fluid Dynamic (CFD) codeshave the potential to reflect the 3-dimen-sional nature of flow phenomena andconsider the local flow properties. Thisapproach could overcome the above-mentioned limitations. CFD codes arewidely used for single-phase flows in theautomotive or aviation industry, but havestill to be qualified for two-phase flows.Due to the limited computational power it is presently not possible, and will not be within the next decades, to resolve the interfacial area of a two-phase flowcompletely for technically relevant flows.Instead, averaging procedures have to beused, which cause a loss of informationregarding the interface. This informationhas to be supplemented by using so-calledclosure models. The main target of ourwork is to provide and validate suchmodels and their interplay in simulationsfor relevant applications [1]. This task,however, requires detailed and reliableexperimental data from multiphase flow

experiments ranging from the study ofseparated flow phenomena in simpledesktop flow channels to the testing of rigs with industrially relevant geometry,pressure and temperature scales, such as it is possible in the Rossendorf TOPFLOWfacility.

Advanced measuring techniquesapplied in the TOPFLOWexperimentsThe Rossendorf TOPFLOW facility allowsto conduct experiments at scales andoperational parameters close to thosefound in the industry including nuclearpower plants. The unique feature ofTOPFLOW is that it is equipped with the most advanced measuring techniquesthat provide experimental data with amaximum of possible resolution in spaceand time. Among those techniques, thereare several optical methods for measuringseparated or diluted bubbly flows andwire-mesh sensors for dense bubbly flows,which are more relevant to practicalapplications.

The wire-mesh sensor technology wasdeveloped at the Institute of SafetyResearch and is successfully used here as well as in many other internationalresearch facilities. The wire-mesh principleis based on fast measurements of theelectrical conductivity between thecrossing points of two rectangular planesof wire electrodes. This allows to acquirecross-sectional phase fraction distributionsat high speed (Fig. 1). A typical wire-meshsensor used in TOPFLOW, capable ofoperating at pressures up to 7 MPa,provides flow structure details with aspatial resolution of 3 mm and at a rate of2.500 frames per second. From the raw

Thermal fluid dynamics:Two-phase flow – experiment and simulation

Research

*Department of Mechanical and Process Engineering, Eidgenössische Technische Hochschule Zürich, Switzerland

Photo: Sven Claus

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data, characteristic multiphase flowparameters, such as time averaged localgas volume fraction distributions resolvedwith respect to the bubble size, can beobtained. Furthermore, velocity can bemeasured by using correlation techniques.

Such detailed data are world-wide uniqueand used for CFD code development andvalidation by a number of national and

international partners. The latest devel-opment is the preparation of a newimaging technique for flow measurement,namely ultra fast electron beam X-raytomography. This new technique will notdisturb the flow and provide flow data attemporal and spatial resolution equal oreven better than wire-mesh sensors [2].

Qualification of Computational Fluid Dynamics (CFD) codes for two-phase flowsIn adiabatic two-phase flows, the flowstructure depends on the momentumtransfer between the phases. Therefore,the momentum transfer between bubblesand the surrounding liquid is reflected inadvanced CFD tools by closure models for the so-called bubble forces. From

Rossendorf Beamline


Structure of Matter

Life Sciences

TOPFLOW FacilityHigh Magnetic Field Lab.

PET Center

Ion Beam Center

Radiation Source ELBE

Fig. 1: Measuring principle of wire-mesh sensors,simplified scheme of the sensor (above) and virtualside projections of the void distribution obtained bythe sensor in a DN200 vertical test section forincreasing gas volumetric fluxes Jair and a constantwater volumetric flux of Jwater = 1 m/s (bottom).

0.037 0.057 0.090 0.14 0.22 0.34 0.53 0.84 1.30

Jair [m/s]


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investigations on single bubbles it is knownthat these forces strongly depend on thebubble size and one of them, namely thelift force, even changes its sign withincreasing bubble size. This was confirmedfor the first time for poly-dispersed flowsby our experiments in vertical pipes. It wasconcluded from the experimental findingsthat the resulting separation of small andlarge bubbles has to be considered for aproper simulation of poly-dispersed bubblyflows. Based on these findings, theInhomogeneous MUSIG model [3] wasdeveloped at the Institute of SafetyResearch and implemented in a numericaltest solver which considers a number ofdifferent bubble size classes (Fig. 2). Themodel allows the consideration of anumber of bubble classes for the massbalance as well as for the momentumbalance. It was implemented into the CFXcode jointly with ANSYS and is now part of the ANSYS CFX code. To prove theapplicability of the Inhomogeneous MUSIGconcept and the proposed closure modelsfor more complex flows with pronounced3D effects, experimental data wasobtained for a flow around a half-moonshaped obstacle within a DN200 pipe.

Such advanced two-phase flow modelsalso offer new insights into the characterof industrially relevant flows. One exampleis related to the bubble columns, which arein wide use. It was shown that transitionsfrom homogeneous to heterogeneous flowregimes are strongly connected to the liftforce inversion [4].

Further experimental and theoreticalstudies around TOPFLOW are devoted to stratified flows, impinging jet config-urations and two-phase flows with phasetransfer. The experiments and the codedevelopment are harmonized within theGerman CFD initiative. TOPFLOW is thereference facility of this initiative. Most ofthe work is done in the framework of twoprojects funded by the German FederalMinistry of Economics and Technology(BMWi), but some special projects andtasks are also supported by other sources,as for example by the European NURESIMproject. Currently, experiments onPressurized Thermal Shock (PTS) phe-nomena are under preparation jointlyfinanced by the French CEA, EDF, AREVA-NP, IRSN and the Swiss PSI.

References*[1] Modeling of the evolution of bubbly

flow along a large vertical pipe,D. Lucas, E. Krepper, H.-M. Prasser, Nuclear Technology 158, 291 – 303 (2007)

[2] Evaluation of a limited angle scanned electron beam X-ray CT approach for two-phase pipe flows, M. Bieberle, U. Hampel, Measurement Science and Technology 17, 2057 – 2065 (2006)

[3] On the modelling of bubbly flow in vertical pipes, E. Krepper, D. Lucas, H.-M. Prasser, Nuclear Engineering and Design 235, 597 – 611 (2005)

[4] Influence of the lift force on the stability of a bubble column, D. Lucas, H.-M. Prasser, A. Manera, Chemical Engineering Science 60, 3609 – 3619 (2005)

Project partners1ANSYS Germany GmbH, Otterfing, Germany

2Gesellschaft für Anlagen- und Reaktor-sicherheit, Garching, Germany

3AREVA-NP, Erlangen, Germany/ Paris, France

4Commissariat à l’énergie atomique (CEA), France

5School of Chemical, Environmental and Mining Engineering (SChEME), University of Nottingham, United Kingdom

*In this report we quote mainly the most important papers that were published by FZD scientists and their partners.

(left: Jwater = 1.017 m/s, Jair = 0.004 m/s; middle: Jwater = 1.017 m/s, Jair = 0.057 m/s;right: Jwater = 0.405 m/s, Jair = 0.140 m/s).

Fig. 2: Comparison of calculated and measured radial gas volume fractionprofiles for different combinations of water and air volumetric fluxes

Ulrich Rohde, Ulrich Grundmann, Sören Kliem

The computer code DYN3D In nuclear reactors, transient processeswith a significant reactivity insertion mayoccur, leading to an increase and 3D re-distribution of the fission power density inthe reactor core in a very short time. Thesetransients can be induced by local changesin the temperature or density of thematerials (fuel, moderator, absorber) or by the movement of the control rods. To ensure the inherent safety by a properreactor design, and to estimate andminimize the consequences of hypotheticalaccidents, accident scenarios have to bemodeled by adequate simulation tools. A best-estimate tool for simulating thedynamics of water-cooled reactors is the computer code DYN3D which wasdeveloped at the FZD Institute of SafetyResearch. It comprises a 3D-neutronkinetics model, a thermal-hydrauliccalculation module, and a fuel rod model.The neutron kinetics model is based on thesolution of the 3-dimensional two-groupneutron diffusion equation by nodalexpansion methods. By means of thethermal-hydraulic model, the density andtemperature of the coolant are obtainedunder one- and two-phase flow con-ditions. By solving the corresponding heatconduction equations, fuel and claddingtemperatures are calculated. These para-meters are important for the thermal-hydraulic feedback on the neutron kineticsas well as for assessing the safety of thereactor. The nuclear cross sections in theneutron diffusion equations do not onlydepend on the feedback parameters, butalso on the nuclide concentrations and theneutron spectrum, which change with theburn-up of the fuel. These dependenciesmust be taken into account providingcorresponding cross section libraries. Fig. 1 shows the interaction of the neutronkinetics, thermal hydraulics, and neutron

cross sections. The DYN3D core model waslinked to thermo-hydraulic system codes[1] providing boundary conditions for thecore, such as coolant inlet temperature and pressure and coolant mass flow ratedistribution. System codes model thethermo-fluid dynamics of the primary and secondary circuit including all majorcomponents of the plant.

DYN3D is undergoing continuousdevelopment with respect to theimprovement of physical models andnumerical methods. Recently, a multi-group approach has been implemented inorder to improve the description of spectraleffects, which are increasingly importantfor mixed-oxide reactor core loadings ofLight Water Reactors, but also forinnovative reactor concepts. A neutrontransport method was developed forDYN3D to overcome the limitations of the diffusion approximation. Within thisapproach, even a pin-wise calculation ofthe power distribution is offered. This wasrecognized internationally with stronginterest [2, 3]. The extended DYN3Dversion was integrated into the Europeancode platform NURESIM. An interface tothe platform was developed, which is

based on the NURESIM softwareenvironment SALOME. This allows linkingDYN3D to other components of theplatform, e.g., to advanced fluid dynamicssimulation tools (CFD codes). In 2006,eight research projects related directly to the improvement, validation, andapplication of DYN3D were running orcompleted. Moreover, licenses for DYN3D,including commercial ones, were providedto 12 users in Germany and Europe.

Within a PhD project, a version of DYN3Dfor dynamics studies of molten salt reactors(MSR), which belong to the ‘GenerationIV’ concepts, was developed [4]. Analyseswere performed for a number of specificMSR transients demonstrating the inherentsafety of this reactor.

Analysis of a hypothetical borondilution scenarioA reactivity initiated transient can beinduced by the perturbation of the boronconcentration in the core of a pressurizedwater reactor. Boron is added to thereactor coolant as a neutron absorbercompensating the excess of reactivity inthe fresh core at the beginning of the fuelcycle. Due to different mechanisms or

DYN3D – advanced reactor simulations in 3D

Rossendorf Beamline


Structure of Matter

Life Sciences


PET Center

Ion Beam Center


DYN3D3D Core model

Steady State and Transient

Neutron Kinetics Thermal Hydraulics

• 2-neutron groups• diffusion theory• 3-dimensional• nodal methods• version for quadratic assemblies

hexagonal assemblies

cross sections of nodes

nodal powers

• 1D 4-equations th. modelfor two phase flow

• radial heat conduction in fuel clad

• heat transfer model• safety parameters• boron mixing models

fuel temperaturescoolant densitiescoolant temperaturesboron concentrations

calculation of cross sections

Fig. 1: Scheme of interaction of the different models in the DYN3D code.

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• library of nuclear group constants• burnup distribution


system failures, for instance as aconsequence of a small break loss ofcoolant accident, slugs of low boratedwater can accumulate in the primarycooling system. During the start-up of thecoolant circulation—after refilling theprimary circuit with emergency coolingwater—or by switching on the first maincoolant pump (MCP), these slugs aretransported into the reactor core causing a reactivity insertion by decreasing theamount of the neutron absorber. The boronconcentration in the reactor core resultsfrom turbulent mixing along the flow pathin the reactor vessel. In this case, mixingthe de-borated condensate with boratedwater is the only mitigative mechanism toprevent re-criticality of the shut-downreactor and impermissible power excursion[5]. Computational Fluid Dynamics (CFD)methods are applied, allowing to ascertainthe time-dependent boron concentrationat each position of the fuel element [6].Experiments performed at the RossendorfCoolant Mixing test facility ROCOM wereused for the validation of the code [7].

ROCOM is a test facility for investigatingthe mixing of the coolant in a linear scaleof 1:5.

The analysis of a boron dilution scenariowith an inadvertent start-up of the firstmain coolant pump for German Konvoitype reactors was performed usingDYN3D. This analysis is aimed at showingthe integrity of the fuel rods even undersuch extreme conditions. Analyzing theboron dilution scenarios is a challengebecause the distribution of the boronconcentration depending on space andtime is crucial for the induced reactivityinsertion. The boron distribution isobtained by modeling the mixing of thede-borated slug with the ambient coolantin the reactor by means of CFD. Fig. 2shows the distribution of the boronconcentration at the reactor core inletwhen the boron content is at its minimum.DYN3D transient calculations wereperformed for different slug volumes.Considering the bounding scenario with aslug size of 36 m3, the reactor becomespromptly super-critical (maximumreactivity of about 2 $), leading to a veryfast power excursion with a peak power ofabout 7000 MW (about twice of nominalpower). Fig. 3 shows the time behavior ofthe reactor power. However, the powerexcursion is limited by the very effectiveDoppler feedback of the fuel temperature.The width of the power peak in time isonly about 25 ms. Therefore, the integralenergy release in the power peak is limited.The fuel temperature remains below800 oC, i.e., far below the melting point.There is local coolant boiling in the hottestfuel assemblies, but no cladding super-heating occurs. It can be concluded from

the analyses that even in the case of aconservatively large volume of un-boratedwater, the safety criteria are met and theintegrity of the core is not endangered.The investigations have shown largemargins if a realistic approach to themodeling of the coolant mixing is applied.

References[1] Analyses of the V1000CT-1 benchmark

with the DYN3D/ATHLET and DYN3D/RELAP coupled code systems including a coolant mixing model validated against CFD calculations,S. Kliem, Y. Kozmenkov, T. Höhne, U. Rohde, Progress in Nuclear Energy 48, 830-848 (2006)

[2] A nodal expansion method for solving the multigroup SP3 equations in the reactor code DYN3D, C. Beckert, U. Grundmann, M&C+SNA 2007, Monterey, USA

[3] Development and verification of a nodal approach for solving the multigroup SP3 equations, C. Beckert, U. Grundmann, Annals of Nuclear Energy (2007), doi:10.1016/j.anucene.2007.05.014.

[4] DYN3D-MSR spatial dynamics code for molten salt reactors, J. Krepel, U. Grund-mann, U. Rohde, F.-P. Weiss, Annals of Nuclear Energy 34, 449 - 462 (2007)

[5] Core response of a PWR to a slug of under-borated water, S. Kliem, U. Rohde, F.-P. Weiss, Nuclear Engineering and Design 230, 121 – 132 (2004)

[6] Modeling of a buoyancy-driven flow experiment at the ROCOM test facility using the CFD-codes CFX-5 and TRIO_U, T. Höhne, S. Kliem, U. Bieder1, Nuclear Engineering and Design 236, 1309 – 1325 (2006)

[7] Fluid mixing and flow distribution in the reactor circuit – Measurement data base, U. Rohde, S. Kliem, T. Höhne, R. Karlsson2, B. Hemström2, J. Lillington,T. Toppila3, J. Elter, Y. Bezrukov, Nuclear Engineering and Design 235, 421 – 443 (2005)

Project partners1CEA (France)2Vattenfall (Sweden/Germany)3Fortum Nuclear Engineering (Finland)4TÜV Süddeutschland (Germany)5VGB PowerTech (Germany)6AREVA (France/Germany)7Nuclear Research Institute Řež (Czech Rep.)

Fig. 3: Reactor power(relative to nominal)during a boron dilutiontransient.

Fig. 2: Boron concentration distribution overthe core inlet cross section at the moment ofminimum boron content.

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15

Sven Eckert, Gunter Gerbeth

Electromagnetic fields represent anattractive tool to influence the flow and, in turn, the heat and mass transfer inelectrically conducting fluids such as liquidmetals or semiconductor melts. The mostattractive feature of this magnetic controlis that it works without contact, which isessential for hot and aggressive melts like liquid steel, aluminum, or silicon. Ingeneral, steady magnetic fields slow downthe melt flow or suppress turbulentfluctuations, whereas alternating magneticfields set the liquid in motion. Yet today,the challenge consists more and more in an inverse approach: a desirable flow fieldmade possible by tailored magnetic fields.This inverse approach constitutes the keyelement of the Collaborative ResearchCentre (SFB) 609 at the Technische Uni-versität Dresden, in which we areintensively involved.

Experimental modeling andmeasuring techniquesExperiments with hot metallic melts (T > 600 °C) are difficult to carry out,expensive, and to some extent meaning-less as long as the necessary measuringtechniques for such melts are still lacking.Experimental data of the melt velocity are,however, indispensable for optimizing themelt flow. To fill in this gap, we developeda basic approach for performing cold liquidmetal model experiments [1] together withvelocity measuring techniques that allowmeasuring almost any interesting flowquantity up to about 300 °C. Our mainmodel melt is the ternary alloy GaInSn,which is liquid at room temperature, buttin or lead based alloys with meltingtemperatures lower than 200 °C are alsoused. Today, ultrasonic Doppler veloci-metry (UDV) has become the primaryvelocity measuring technique [2]. Itprovides an instantaneous velocity profilealong the ultrasonic beam and can evenoperate through the wall of the meltcontainer.

X-ray radiography presents a promisingtool for visualizing processes in opaquemetal melts in the future. For example,solidification processes or the motion ofgas bubbles in liquid metals can be directlyobserved. As the Radiation Source ELBE atthe FZD provides channeling radiation, anew X-ray lab was set up there. This willallow investigating a wide range ofdifferent alloys with both a high timeresolution and an excellent signal-to-noiseratio. Fig. 1 shows solidification studies fora GaIn alloy performed with a microfocusX-ray tube. The brighter parts indicate thelighter gallium melt. A quantitative analysisof the brightness distribution allows re-constructing the thermosolutal convectionin front of the solidified dendrites (Fig. 1b).

Metal castingToday, new applications in the automotiveand aviation industries are a challenge forthe metal casting industry. In metalcasting, the pouring process is known as a critical issue with respect to the castingquality. The high velocity at the beginningof the pouring process is a particularproblem which is expected to have asignificant influence on typical castingproblems such as the entrapment of gasbubbles or inclusions into the casting units.This causes inhomogeneities in themicrostructure which may significantlydeteriorate the mechanical properties ofthe casting products.

Model experiments with the GaInSn melt revealed the critical importance of the incoming melt front. Fig. 2 showssnapshots of the initial moment of thepouring process in an industrial casting unitwhich is cut open here for the purpose ofmelt flow visualization. The melt front inthe form of a breaking wave (Fig. 2a)

Magnetic flow control in metal casting and crystal growth

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Fig. 1: X-ray visualization of a solidifying GaIn melt. (a) Brightness distribution, (b) Brightness isolinesand recalculated thermosolutal convection in the melt.


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implies a high rate of gas bubbleentrapment. This finally results in theinclusion of recognizable gas bubbles inthe solidified microstructure in Fig. 3a.However, we were able to suppress theincoming breaking wave via magneticcontrol of the melt flow (Fig. 2b), whichimproved the microstructure (Fig. 3b). In a series of several hundred castings of aluminum alloys, the rate of castingfailures was reduced by around four due to magnetic control of the pouring process [3].

Recent model experiments on gas-bubbleliquid metal two-phase flows showed thatapplying a steady magnetic field does notalways result in flow stabilization. Instead,it gave rise to velocity fluctuations in alimited range of magnetic field strengths[4]. In the future, this may qualitativelychange the use of electromagnetic brakesin the two-phase nozzle region of theindustrial continuous steel casting process.

Crystal growth from the meltToday, single silicon or gallium-arsenidecrystals are mainly grown from the melt.The quality, size, and growth rate of thecrystals as well as the stability of thegrowth process strongly depend on the motion in the melt and relatedtemperature fields. Typically, the melt is requested to show a flat solid-liquidinterface, a low level of temperaturefluctuations, and a controlled transport of oxygen or dopants. Magnetic fields area powerful tool to provide this melt flowcontrol. Scientists are particularly interestedin gaining knowledge and control of theflow stability in order to keep the melt flowlaminar, if possible [5]. As with larger meltsizes, the flow is always turbulent.However, tailored magnetic fields can be applied to reduce the temperaturefluctuations significantly, for instance [6].The flow topology, in turn, has a stronginfluence on the dopant distribution in thegrown crystal [7].

References[1] Liquid metal model experiments on

casting and solidification processes, A. Cramer, S. Eckert, V. Galindo, G. Gerbeth, B. Willers, W. Witke, Journal of Materials Science 39, 7285 (2004)

[2] Velocity measurement techniques for liquid metal flows, S. Eckert, A. Cramer, G. Gerbeth, in: Magnetohydrodynamics: evolution of ideas and trends, S. Molokov, R. Moreau, H.K. Moffatt (eds.), Springer, 2007, 275 - 294

[3] Use of magnetic fields in aluminium investment casting, G. Gerbeth, S. Eckert, V. Galindo, B. Willers, U. Hewelt1, H.-W. Katz1, M. Ziemann1, EPM 2006, Sendai, Proc. 323

[4] The flow structure of a bubble-driven liquid metal jet in a horizontal magnetic field, C. Zhang, S. Eckert, G. Gerbeth, Journal of Fluid Mechanics 575, 57 (2007)

[5] Stability of melt flow due to a traveling magnetic field in a closed ampoule, I. Grants, G. Gerbeth, Journal of Crystal Growth 269, 631 (2004)

[6] Experimental study of the suppression of Rayleigh-Benard instability in a cylinder by combined rotating and steady magnetic fields, I. Grants, A. Pedchenko2, G. Gerbeth, Physics of Fluids 18, 124104 (2006)

[7] Breakdown of Burton-Prim-Slichter theory and lateral solute segregation in radially converging flows, J. Priede3, G. Gerbeth, Journal of Crystal Growth 285, 261 (2005)

Project partners1Aluminium Feinguss Soest Ltd., Soest, Germany

2Institute of Physics, Riga, Latvia3Coventry University, United Kingdom

Fig. 2: Photos from a high-speed video camera showing the initial melt flow in a pouring process. (a) Without magnetic control, (b) with magnetic control of 1 Tesla.

Fig. 3: Microstructure of a cast aluminum alloy. (a) Without magnetic control, (b) with magnetic control of 0.86 Tesla.

17

Frank Stefani, Gunter Gerbeth, Thomas Gundrum

Magnetic fields are ubiquitous in thecosmos. Planets, stars and galaxiesproduce their own fields by movingelectrically conducting fluids, which iscalled hydromagnetic dynamo effect.However, magnetic fields are not onlypassive by-products of fluid motion. As aconsequence of the magnetorotationalinstability (MRI), they also play an activerole in cosmic structure formation. Duringthe last ten years, significant progress hasbeen made in the experimentalinvestigation of both effects. We brieflyreport our involvement in this process.

Dynamo experiments, field reversals,and magnetic flow tomography After the 1999 experiments in Riga andKarlsruhe had marked a breakthrough indynamo science [1], many activities aroundthe world aimed at studying magnetic fieldself-excitation in a variety of liquid sodiumfacilities. In Riga, a total of sevenexperimental campaigns have delivered awealth of ever-refined measurement dataon the kinematic and the saturateddynamo regime. Much effort was spent onthe numerical simulation resulting in therecent quite accurate understanding [2] ofthis paradigmatic hydromagnetic dynamo(Fig. 1).

The codes developed for the simulation ofthe Riga dynamo were also applied to theFrench “von Karman sodium” (VKS)experiment. Our numerical findings [3]helped the VKS team to make their facilitya working dynamo which even shows asort of magnetic field reversals. We haveanalyzed this fascinating phenomenonwithin a simplified mean-field dynamomodel which already exhibits manyfeatures of the earth’s magnetic fieldreversals in a realistic manner [4, 5].

As a spin-off of our dynamo activities wehave developed the “Contactless InductiveFlow Tomography” (CIFT) [6] which has apromising potential for a fully contactlessflow measurement in crystal growth andmetallurgy. CIFT constitutes the mainsubject of the European projectMAGFLOTOM, which was started inFebruary 2007 and is coordinated by theFZD.

Experiments on themagnetorotational instabilityThe magnetorotational instability explainswhy stars and black holes can accretematter from the gas disks surroundingthem. Before being swallowed by thecentral object, the gas in such accretiondisks has to loose its angular momentum.It has been shown that the molecularviscosity in the disks is much too small toexplain the needed angular momentumtransport. Turbulence could well do thejob, but hydrodynamics teaches us thatrotating flows with outward increasingangular momentum are stable. Here is thepoint where magnetic fields come into playas a catalyst to destabilize flows which areotherwise hydrodynamically stable.

The experiment PROMISE (PotsdamROssendorf Magnetic InStabilityExperiment) is a joint project of FZD and

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Fig. 2: Scheme of the PROMISE experiment. The axial magnetic field is produced by currentsin the large yellow coil. The axial copper tube inthe center carries currents up to 8000 Amps toproduce the azimuthal field.

Fig. 1: Riga dynamo experiment: scheme of thefacility (a), and simulated structure of the self-excited magnetic eigenfield (b).


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Astrophysikalisches Institut Potsdam (AIP)and is supported by the Leibniz Gemein-schaft in the framework of its SAWprogram. PROMISE traces back to aproposal by Hollerbach (Department ofApplied Mathematics, University of Leeds)and Rüdiger (AIP) to use helical instead ofpurely axial magnetic fields in order tomake an MRI experiment feasible withreasonable effort. Fig. 2 shows theexperimental set-up which basicallyconsists of a Taylor-Couette cell of the

liquid alloy GaInSn which can be exposedto a helical magnetic field. A typical featureof the MRI is visible in Fig. 3 and Fig. 4which show that the instability in form of a traveling wave appears only in a finiteinterval of the applied magnetic field.More details about this experiment can befound in [7, 8]. Presently, we modify theset-up in order to make the transitionbetween the stable and the unstable floweven sharper.

References[1] Laboratory experiments on hydro-

magnetic dynamos, A. Gailitis1, O. Lielausis1, E. Platacis1, G. Gerbeth, F. Stefani, Reviews of Modern Physics 74, 973 (2002)

[2] Coupled fluid-flow and magnetic field simulation of the Riga dynamo experiment, S. Kenjeres2, K. Hanjalic2, S. Renaudier2, F. Stefani, G. Gerbeth, A. Gailitis1, Physics of Plasmas 13, 122308 (2006)

[3] Ambivalent effects of added layers on steady kinematic dynamos in cylindrical geometry: application to the VKS experiment, F. Stefani, M. Xu, G. Gerbeth, F. Ravelet3, A. Chiffaudel3, F. Daviaud3, J. Leorat4, European Journal of Mechanics B/Fluids 25, 894 (2006)

[4] Asymmetric polarity reversals, bimodal field distribution, and coherence resonance in a spherically symmetric mean-field dynamo model, F. Stefani, G. Gerbeth, Physical Review Letters 94, 184506 (2005)

[5] Why dynamos are prone to reversals, F. Stefani, G. Gerbeth, U. Günther, M. Xu, Earth and Planetary Science Letters 243, 828 (2006)

[6] Contactless inductive flow tomography,F. Stefani, Th. Gundrum, G. Gerbeth, Physical Review E 70, 056306 (2004)

[7] Experimental evidence for magneto-rotational instability in a Taylor-Couette flow under the influence of a helical magnetic field, F. Stefani, Th. Gundrum, G. Gerbeth, G. Rüdiger5, M. Schultz5, J. Szklarski5, R. Hollerbach6, Physical Review Letters 97, 184502 (2006)

[8] The traveling wave MRI in cylindrical Taylor-Couette flow: comparing wave-lenghts and speeds in theory and experiment, G. Rüdiger5, R. Hollerbach6, F. Stefani, Th. Gundrum, G. Gerbeth, R. Rosner7, The Astrophysical Journal Letters 649, L145 (2006)

Project partners1Institute of Physics, Riga, Latvia2Delft Technical University, Delft, The Netherlands

3CEA Saclay, Gif-sur-Yvette, France4LUTH, Observatoire de Paris-Meudon, France

5Astrophysikalisches Institut Potsdam, Germany

6Department of Applied Mathematics, University of Leeds, United Kingdom

7Department of Astronomy and Astrophysics, University of Chicago, USA

Fig. 3: Comparison of measured andcomputed wavefrequency (normalizedwith the rotation rateof the inner cylinder)and predicted criticalrotation rate of theinner cylinder. MRI is observed in thepredicted interval ofcoil currents between30 A and 110 A.

Fig. 4: Measured axialvelocity in dependenceon axial position andtime. The travelingwave appears only atmedium values of thecoil current.

19

Eberhard Altstadt, Hans-Georg Willschütz,Frank-Peter Weiss

From the very beginning of the peacefuluse of nuclear energy, a high safety levelhas been a major target within thedevelopment of nuclear power plants. Thesevere accident at Three Mile Island in1979 provided a strong impetus for severeaccident research during the last threedecades. On the one hand, Three MileIsland showed that core meltdownscenarios are not hypothetical, but, on theother hand, it proved the safety margin ofthe pressurized water reactor system.

The FZD focuses on the thermomechanicalbehavior of the most important safetybarrier—the reactor pressure vessel(RPV)—during a postulated severeaccident. In this case, the cooling of thereactor core cannot be re-established. Themain question is: Can the reactor pressurevessel withstand a core meltdown ifexternal cooling can be arranged? If thefailure of the reactor pressure vessel cannotbe excluded, potential failure modes andthe time to failure have to be known inorder to assess the possible loads on thecontainment. To solve these questions, acoupled thermal-mechanical finite elementmodel was developed evaluating thetransient temperatures in the melt pooland in the vessel wall as well as theviscoplastic deformation of the reactorpressure vessel [1 – 3]. The coupling not

only allows considering the temperaturedependence of the material parametersand the thermally induced stress, but italso takes into account the response of thetemperature field itself upon the changingvessel geometry. New approaches areapplied to the simulation of creep anddamage. The mechanical damage for eachwall element is incremented after eachtime step according to:

(1)

In other words, the two possible strainincrements—creep and plastic strain—areweighted against the according rupturestrain. So initially the damage is zero; if avalue of 1 is reached, the correspondingelement is “killed”. The coefficient Rν

considers the influence of the three-dimensional stress state according to amodel proposed by Lemaitre [4], sincehigh triaxiality makes the material brittle.The new models were widely validated by pre-test and post-test calculations onseveral internationally scaled in-vesselretention experiments, e. g., on theFOREVER tests, performed at the RoyalInstitute of Technology Stockholm [2, 3].Figure 1 shows the calculated temperaturefield and damage distribution within theFOREVER vessel wall in comparison tometallographic post-test investigations.

The simulations of prototypic scenariosshow that in-vessel retention of the meltcould be possible by external flooding evenat increased pressure and in reactors withhigh power. Two patents for passivedevices were derived from the insightsgained (Fig. 2): The first device (“CreepStool Plates”) supports the lower headpole part of the reactor pressure vessel. Itreduces the maximum mechanical load inthe highly stressed area of the hot focus(see Fig. 1). In this way, it can preventfailure or at least extend the time to failureof the vessel, even in the case of a totallydry scenario. The second device triggers

passive flooding of the reactor pit with theweight of the downward moving lowerhead, which relocates due to thermalexpansion, creep, and plastic deformation(cf. Fig. 2).

The reactor pressure vessel – a strong barrier to retain corium

References[1] Simulation of scaled vessel failure

experiments and investigation of a possible vessel support against failure,H.-G. Willschütz, Nuclear Engineering and Design 228, 401 – 414 (2004)

[2] Insights from the FOREVER-Programme and the Accompanying Finite Element Calculations, H.-G. Willschütz, E. Altstadt, F.-P. Weiss, B.R. Sehgal1, atw - International Journal for Nuclear Power 5, 345 – 349 (2004)

[3] Recursively coupled thermal and mechanical FEM-analysis of lower plenum creep failure experiments,H.-G. Willschütz, E. Altstadt, B.R. Sehgal1, F.-P. Weiss, Annals of Nuclear Energy 2, 126 – 148 (2006)

[4] A Course on Damage Mechanics,J. Lemaitre, 2nd edition, Berlin, Heidel-berg, New York, Springer-Verlag (1996)

Project partners1Royal Institute of Technology (KTH), Stockholm, Sweden

2Commisariat a l’ Energie Atomique (CEA), France

3Institut de Radioprotection et de Sûreté Nucléaire (IRSN), France

4Alexandrov Research Institute St. Petersburg, Russia

5Gesellschaft für Reaktorsicherheit (GRS), Germany

Fig. 1: Calculated temperature field and damage(cf. equation (1)) distribution within the vesselwall for the FOREVER EC2 test and comparisonwith metallographic post-test investigations.

Fig. 2: Devices for mitigation of core meltdownaccidents.

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Frank Bergner, Andreas Ulbricht, Hans-Werner Viehrig

The reactor pressure vessel (RPV) of anuclear power plant (NPP) is the mainbarrier against the emission of fissionproducts into the environment; it is notreplaceable and it therefore limits theoperation duration. The structural integrityof the reactor pressure vessel must bemaintained throughout the operationaltime of a nuclear power plant undernormal operation as well as under accidentconditions. During operation, the mech-anical properties of the pressure vessel arechanged mainly due to irradiation with fast neutrons. This leads to an increase in hardness and an unwanted loss ofductility—in other words, the reactorpressure vessel grows old. The reasons forthe ageing of RPV steels are complex andcan be traced down to the nanometerscale: Irradiation with fast neutrons givesrise to displacement cascades in the crystallattice accompanied by a substantialincrease in the concentration of vacancies,which in turn serve as vehicles for long-term diffusional rearrangements of atoms.The resulting nanometer-sized defect-

solute clusters are obstacles to the motionof dislocations, i.e., one-dimensionalcrystal defects acting as “quanta” ofplastic deformation. In other words, thematerial hardens which is associated with a loss of ductility. The irradiation-inducedclusters are thermodynamically metastable,they dissolve at temperatures of about450°C and give rise to the recovery of themechanical properties. In order to meet thehighest standards of reactor safety and to develop advanced reactor concepts, abetter and more detailed understanding ofthe property changes and the responsiblemicrostructural mechanisms is required.The FZD contributes to these internationalefforts by experimental as well ascomputational means.

How to apply advanced fracturemechanics concepts to RPV integrity assessmentThe Master Curve (MC) approach is a new fracture mechanical methodologydeveloped to describe the fracturetoughness behavior in the lower ductile-to-brittle transition (DBT) range of ferriticsteels. This approach is rapidly moving

from research to application, as it is used for assessing the integrity of thecomponents and structures and thus of the reactor pressure vessel. The Institute of Safety Research contributes to thevalidation of the Master Curve conceptand to its application to irradiated RPVsteels [1]. The main question is whetherthe universal shape of the Master Curve ischanged by neutron irradiation, which wasinvestigated within a project funded by theGerman nuclear safety program [2]. Theproject was aimed at testing irradiatedspecimens of different RPV steels.

Fracture-toughness values KJc at brittlefailure of the specimens were measured fora reference RPV steel highly sensitive toneutron embrittlement. Fig. 1 shows theductile-to-brittle transition temperatureshift (up to 230 K) as a consequence of the neutron dose expressed in units ofdisplacements per atom (dpa). Generally,the KJc values follow the universal shape ofthe Master Curve for a fracture probabilityof 50% (lines in Fig. 1). We found that thephysical background of the Master Curveapproach is valid even for the RPV steel inthe highly embrittled condition. Thecoincidence of the curves for the irradiatedand annealed condition (IA) with theunirradiated reference (U) indicates thecomplete recovery of the toughnessproperties.

Taking snapshots of the sizedistribution of defect-solute clusters by SANSSmall-angle neutron scattering (SANS) is an advanced experimental techniquewhich is unique in its capability to resolvethe size-distribution of clusters at nano-meter resolution while probingmacroscopic volumes. Fig. 2 displays the measured size distributions for theinvestigated reference RPV steel.

How reactor pressure vessels grow old

Hot cells for investigating irradiated reactor material.

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We found that the volume fraction ofdefect-solute clusters increases with thedose, whereas the mean radius isapproximately constant. For the highestdose, post-irradiation annealing treatmentsat different temperatures give rise tocluster dissolution. Despite the complexityof the dissolution process in steels, thedissolved fraction exhibits an Arrheniusbehavior. It is assumed that the apparentactivation energy of 1.2 eV is a fingerprintof the rate-controlling step of the dissol-ution process [3]. In order to confirm the

relevance of these findings, the Vickershardness was measured for the samesamples which were used for the reportedSANS measurements. Fig. 3 indicates astrong correlation between the increase inVickers hardness induced by irradiationand the square root of the cluster fractionfor both irradiated and annealed con-ditions. The re-irradiation behavior afterannealing was investigated for a RPV weldmaterial used for Russian VVER440-typereactors [4]. We have observed that acertain fraction of the irradiation-induced

clusters coarsened and accumulated Cuduring annealing. These Cu atoms are nolonger available for the process of clusterformation during re-irradiation. As aconsequence, the degree of embrittlementis less than for the first irradiation. This isimportant to know for evaluating thelarge-scale annealing treatments per-formed for a number of VVER440-typereactors in several countries and finallycontributes to the highest standards ofreactor safety.

References[1] Application of advanced Master Curve

approaches on WWER-440 reactor pressure vessel steels, H.-W. Viehrig, M. Scibetta1, K. Wallin2, International Journal of Pressure Vessels and Piping 83, 584 (2006)

[2] Microstructural and mechanical characterization of the radiation effects in model reactor pressure vessel steels,A. Ulbricht, J. Boehmert, H.-W. Viehrig, Journal of ASTM International 2, Paper ID JAI12385 (2005)

[3] Small-angle neutron scattering study of post-irradiation annealed neutron irradiated pressure vessel steels,A. Ulbricht, F. Bergner, C.D. Dewhurst3, A. Heinemann4, Journal of Nuclear Materials 353, 27 (2006)

[4] SANS response of VVER440-type weld material after neutron irradiation, post-irradiation annealing and re-irradiation,A. Ulbricht, F. Bergner, J. Böhmert, M. Valo2, M.-H. Mathon5, A. Heine-mann4, Philosophical Magazine 87, 1855 (2007)

Project partners1Belgian Nuclear Research Centre (SCK•CEN) Mol, Reactor Materials Research Unit, Belgium

2Finish Research Centre (VTT) Espoo, Manufacturing Technology, Finland

3Institut Laue-Langevin (ILL), Large Scale Structures Group, Grenoble, France

4Hahn-Meitner-Institut (HMI), Structural Materials Research, Berlin, Germany

5Laboratoire Léon Brillouin (LLB), CEA-Saclay, Materials Group, France

6Russian Research Centre (RRC), Kurchatov Institute, Moscow, Russia

7European Commission, Joint ResearchCentre, Institute for Energy, Petten, Netherlands

8International Atomic Energy Agency (IAEA), Vienna, Austria

Fig. 1: Master Curveevaluation of fracturetoughness KJc valuesmeasured on specimensof the reference RPVsteel in unirradiated (U),irradiated (I) andrecovery annealed (IA)conditions.

Fig. 2: Measured clustersize distribution forirradiated and annealedreference RPV steel(same steel and color-coding as in Fig.1).

Fig. 3: Irradiation-induced hardnessincrease vs. square rootof cluster volume fraction(same steel and color-coding as in Fig.1).

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Design of a photo-neutron source for time-of-flight measurements at the Radiation Source ELBE

Arnd JunghansA, Hartwig Freiesleben1,David LegradyB, F.-P. WeissB, Rainer SchlenkC

At the Radiation Source ELBE, neutrontime-of-flight experiments (nELBE) areenvisaged for energy dispersive studies of neutron interactions with matter.Measuring neutron-induced reaction crosssections for fusion and fission reactors aswell as for accelerator driven systemsaiming at the transmutation of nuclearwaste is one of the tasks to be pursued at the photo-neutron source. Additional

applications arise in the field of astro-physics in improving the reaction rates ofastrophysical nucleo-synthesis models. The short, ps-range pulses of the ELBEaccelerator combined with a small neutronradiator volume allow the photo-neutronsource to have an ultra compact design.

Pulsed neutrons are generated at nELBE when the ELBE electron beam hits theneutron radiator, which is made from liquidlead housed in a molybdenum channelinside a vacuum chamber. The electronpulse structure is transformed into

neutrons with a similar structure. A flightpath of about 4 m is sufficient to separatethe neutron pulses from the bremsstrah-lung flashes and secondary electrons andto determine the neutron energy by thetravel time of their free flight.

The construction of the pulsed photo-neutron source was preceded by detailedsimulations [1, 2]. The calculations provedthat liquid lead is the most appropriateradiator material regarding neutronics aswell as thermal criteria and that molyb-denum is the best suited wall material in

View of the nELBE facility in the neutron hall. The electron-beam line is directed towards the nELBE photo-neutron target on the right side. The electron beam passes through two beryllium vacuum windows into theliquid-lead circuit, where neutrons are produced. It is stopped afterwards in a cylindrical radiation shield.

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the region where the electrons hit theradiator channel. The temperature distribu-tion of in the radiator was simulated usingcomputational fluid dynamics. Fig. 1 showsthe temperature distribution that resultsfrom a 30 kW electron beam with 8 mm

diameter hitting the Mo-radiator with amean lead flow velocity of 1 m/s. Giventhe maximum electron current Ie- = 1 mAof ELBE, the detailed Monte Carlosimulations predict a neutron sourcestrength of 2.7 x 1013 n/s and an averageneutron flux of 1.5 x 107 cm-2 s-1 at themeasuring position for an electron energyof Ee = 40 MeV. Using the new superconducting radio frequency (SRF) photoelectron injector with a repetition rate offe = 0.5 MHz, the measurable neutronenergy ranges between En = 50 keV and10 MeV. We expect the energy resolutionto be better than 1% for energies up to5 MeV. When inserting a thermal neutronfilter of polyethylene and cadmium in thecollimator, the background resulting fromthe previous pulse can be reducedsignificantly (see Fig. 2) so that, forexample, a signal-to-background ratio of105 is achieved for 2.5 MeV neutrons.

Compared to all existing high-resolutionneutron beams nELBE has a verycompetitive luminosity in the accessibleenergy range. The advantage of such asmall design is that the facility retains a high intensity with good resolution,

whereas some other neutron sources lose a significant part of their source intensityadvantage over nELBE when increasingtheir flight path in order to reach an energyresolution of better than 1%.

The design of the nELBE facility is a jointeffort between the FZD Institutes of SafetyResearch and Radiation Physics and theInstitute for Nuclear and Particle Physics ofTechnische Universität Dresden. The facilityis now approaching completion and joinedthe efforts of the EFNUDAT (EuropeanFacilities for Nuclear Data Measurements)project. Ten institutions in seven Europeancountries participate in this project, whichis funded within the 6th frameworkprogramme (FP6) of the EuropeanCommission. The design of nELBE wassupported by the German ResearchFoundation (DFG).

References[1] A photo-neutron source for time-of-

flight measurements at the radiation source ELBE, E. Altstadt, C. Beckert, E. Grosse, H. Freiesleben1, J. Klug, A.R. Junghans, R. Schlenk, F.-P. Weiss et al., Annals of Nuclear Energy 34, 36 – 50 (2007)

[2] Development of a neutron time-of-flight source at the ELBE accelerator, J. Klug, E. Altstadt, C. Beckert, R. Beyer, H. Freiesleben1, V. Galindo, E. Grosse, A.R. Junghans, D. Legrady, B. Naumann, K. Noack, G. Rusev, K.D. Schilling, R. Schlenk, S. Schneider, A. Wagner, F.-P. Weiß, Nuclear Instruments and Methods in Physics Research A, A577 (2007) 641

AInstitute of Radiation Physics of FZDBInstitute of Safety Research of FZDCDepartment Research Technology of FZD

Project partner1 Institute of Nuclear and Particle Physics, Technische Universität Dresden, GermanyFig. 2: Time dependent neutron flux at the measuring position for two consecutive single neutron

pulses, with (squares) and without (triangles) an absorber for low-energy neutrons (Ee- = 30 MeV,Ie- = 1 mA, fe- = 0.5 MHz)

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Fig. 1: Temperature distribution in the liquidlead and in the channel wall for an averageliquid lead flow velocity of 1 m/s (d = 8 mm,Ee- = 30 MeV, Ie- = 1 mA)

RESEARCH INSTITUTE OF RADIOCHEMISTRY

Henry Moll, Gert Bernhard

All over the world, researchers aredeveloping concepts for the disposal andfinal storage of nuclear waste in deepgeological formations (Fig. 1). This isaimed at protecting the population and theenvironment from the risks caused byradioactive and hazardous nuclear waste.One European research facility to test thepotential of crystalline bedrock for storingnuclear waste is the Äspö Hard RockLaboratory (Äspö HRL), located on thesoutheastern coast of Sweden.

Microbes are widely distributed in natureand are capable of strongly influencing themigration of hazardous actinides in theenvironment. This has led to an increasedinterest in studies exploring the interactionprocesses between actinides and bacteriaduring the past several years. It is alsoreflected in the FZD research area “Radio-ecology” which, among other things, isdedicated to actinides in biologicalsystems. Here, we have focused on

exploring the manifold interactionprocesses between the actinide elementplutonium and the sulfate reducingbacterium Desulfovibrio aespoeensis [1].This study, which was partly funded by theGerman Federal Ministry of Economics andTechnology, is part of an internationalcollaboration between FZD and theDepartment of Cell and Molecular Biologyat Göteborg University in Sweden. Insummary, the processes observed in thestudy cause changes of the oxidation stateof plutonium affecting its migrationbehavior.

Our Swedish partners investigated themicrobial diversity at Äspö HRL. The totalnumber of microbes ranges from 1x103 to5x106 cells ml-1, whereas the number ofsulfate reducing bacteria (SRB) wasbetween 1x101 to 2x104 cells ml-1. Theubiquitous SRB strain D. aespoeensis wasisolated from the Äspö site at a depth of600 m [2]. Microorganisms can interactwith actinides directly (Fig. 1) as well asindirectly. For the first time, direct

interaction processes between plutoniumin different oxidation states (+6 and +4)with cells of D. aespoeensis weredetermined [1]. We found out that thereduction of Pu(VI) to Pu(V) by thebacteria leads to an increased dissolutionof the cell-bound plutonium. In contrast tothe release of Pu(V) from the cell surfaceinto the surrounding solution, we observedan immobilization of Pu as Pu(IV) polymersby the biomass.

Plutonium is a hazardous actinide elementwhich exhibits a complicated chemistrybecause it can exist in several oxidationstates (+3, +4, +5 and +6) in an aqueoussolution in environmental conditions.Therefore, studying the interaction ofplutonium with microbes is challenging.Our work demonstrates that there isstrong interaction between the two mainplutonium species, Pu(VI) and Pu(IV)polymers, and the cells of D. aespoeensis.The distribution of the oxidation-states ofplutonium is based on solvent-extractionexperiments and was successfullyconfirmed by X-ray absorption near edgespectroscopy (XANES) performed at theRossendorf Beamline (ROBL) at the ESRFand absorption spectroscopy measure-ments. Based on these results and on thework of Panak and Nitsche [3], wedeveloped a model which describes theprocesses in the system Pu – D.aespoeensis (Fig. 2).

The interaction with plutonium includesfive processes with different time scales.Interestingly, the physiologically verydifferent soil bacteria Pseudomonasstutzeri and Bacillus sphaericus [3] and D.aespoeensis interact with plutonium in asimilar way (processes A to C in Fig. 2). Inthe first step, Pu(VI) and Pu(IV) polymersare bound to the biomass, e.g., on

Bacteria and nuclear waste disposal

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Fig. 1: Nuclear waste disposal in deep geologicalformations and direct interaction processes ofreleased actinides with microbes.

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phosphate groups of the cell envelope.However, in contrast to the results ofPanak and Nitsche [3], who report thatone third of the initial Pu(VI) was reducedto Pu(V) after 24h, we observed that 97%of Pu(VI) was reduced to Pu(V) due to theactivity of the D. aespoeensis cells withinthe same period of time. Most of the Pu(V)

dissolves back to the aqueous solution due to the weak complexing properties of plutonium in this oxidation state. Thedissolved Pu(V) disproportionates to Pu(IV)and Pu(VI). As already described foruranium (Fig. 3), we also assume forplutonium that the structure of the cellmembrane is damaged due to metal stress.

Therefore, we conclude a penetration ofplutonium species (e.g., Pu(IV)-polymers)inside the bacterial cell from the increasedplutonium amount which is strongly boundand not accessible for solvent extractions.It cannot be excluded that additionalinteraction processes such as the asso-ciation of Pu(IV) polymeric species withreleased cell components and/or theuptake of Pu(IV)-polymers by degradedcells take place. Extended X-ray absorptionfine structure (EXAFS) measurements of the plutonium accumulated by D.aespoeensis showed that Pu(IV) polymericspecies are bound to the cells after morethan 96 h of contact time. Moreover, aninteraction of these Pu(IV) polymericspecies with phosphate groups of thebiomass is indicated by the isolation of a Pu-P distance at 3.15 Å.

By characterizing the individual processesbetween D. aespoeensis bacteria andplutonium, this study contributes to a more realistic description of the influenceof microbial actions on the migration be-havior of plutonium in the environment.What is more, it provides an improved riskassessment for potential undergroundnuclear waste repositories.

References[1] The interaction of Desulfovibrio

aespoeensis DSM 10631T with plutonium, H. Moll, M.L. Merroun, C. Hennig1, A. Rossberg1, S. Selenska-Pobell, G. Bernhard, Radiochimica Acta 94, 815 – 824 (2006)

[2] Desulfovibrio aespoeensis sp. nov., a mesophilic sulfate-reducing bacterium from deep groundwater at Äspö hard rock laboratory, Sweden, M. Motamedi2, K. Pedersen2, International Journal of Systematic Bacteriology 48, 311 – 315 (1998)

[3] Interaction of aerobic soil bacteria with plutonium(VI), P.J. Panak, H. Nitsche, Radiochimica Acta 89, 499 – 504 (2001)

Project partners1Rossendorf Beamline (ROBL) at ESRF, Grenoble, France

2Department of Cell and Molecular Biology, Göteborg University, Sweden

3Department of Microbiology, University of Granada, Spain

Process A & D:Simultaneous complexation of Pu(VI)and Pu(IV)-polymers by functionalgroups of the cell surface (e.g.,phosphate groups)

Process B:Fast reduction of Pu(VI) to Pu(V) and dissolution of Pu(V)

Process C:Disproportionation of Pu(V) to Pu(IV) and Pu(VI)

Process E:Indications for a) penetration of Pu inside the cellsb) association/uptake of Pu with/by degraded cells

Fig. 3: Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) analysis ofthe cellular localization of uranium accumulated by cells of Desulfovibrio aespoeensis.

Fig. 2: Illustration of the various processes describing the interaction of plutonium with Desulfovibrioaespoeensis based on the schema developed in [3].

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RESEARCH INSTITUTE OF RADIOCHEMISTRY · INSTITUTE OF RADIATION PHYSICS · DRESDEN HIGH MAGNETIC FIELD LABORATORY

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Katrin Pollmann, Karim Fahmy, Thomas Herrmannsdörfer

Nanobiotechnology is a novel, rapidlygrowing branch of nanosciences andcombines two future technologies:biotechnology and nanotechnology. Oneimportant goal of nanobiotechnology is to utilize the unique properties of bio-molecules and their interactions for theconstruction of nanoscale structures anddevices. In particular, investigation andutilization of self-organizing biomoleculeshave attracted much interest in this field.

Surface layer proteins (S-layers), whichform the outer sheet around the cells of alarge number of primitive microorganisms,

are an example of such fascinating self-assembling nanostructures. They formtwo-dimensional paracrystalline arrays with repeating units on the scale of a fewnanometers (10-9 m). During the last fewyears, the Institute of Radiochemistry hasestablished their utilization as a technologyplatform for innovative materials. Amongthe various S-layer-carrying bacterialstrains which have been isolated fromuranium mining waste piles, the S-layer of Bacillus sphaericus JG-A12 has beenextensively characterized, including proteinstudies, molecular biology, genetic engin-eering, spectroscopic methods, and itsapplication potential [1, 2]. In particular, it has been used to produce highly regulararrays of inorganic nano-sized grains.

S-layers are ideal templates for synthesis,in situ deposition, or direct patterning ofinorganic nanoarrays. Their regularly-distributed pores function as binding sitesfor various metals such as Pt, Pd, and Au,and offer ideal structures for the formationof regularly-distributed nanoclusters ofdefined sizes [1]. Such arrays of nano-particles in a matrix of biological moleculeswith high stability [2] and defined geom-etry have great potential for developingnovel catalysts, new biomedical andbioanalytical applications, the assembly of nanometer-scaled electronic devices, for the optical industry, and storage media.

Using such materials in technologicalapplications critically depends on thedetailed knowledge of their properties onan atomic, nanoscopic, and microscopicscale. In this multidisciplinary field, closecooperation of researchers of variousdisciplines such as biology, chemistry,physics, and material sciences is essential.In collaboration with the Institute ofRadiation Physics, the Dresden HighMagnetic Field Laboratory (HLD), and theInstitute of Ion-Beam Physics and MaterialsResearch of the FZD, the size, distributionand structure of the nanoparticles, physicalproperties, and the mechanisms of protein-metal interactions have been analyzed[1 – 3]. As an example, the properties of S-layer and Pd-nanograin hybrid materialsare presented here.

Regarding palladium nanoclusters withmean grain diameters down to 1.5 nm, aclear reduction of the magnetic properties,e.g., of the magnetic susceptibility,compared to the features obtained frombulk palladium has been observed [3]. It appears that ferromagnetic spinfluctuations on a small length and short

Self-organizing surface layer proteins as building blocks for innovative nanomaterials

Scheme of covering an S-layer with a metal salt solution.

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time scale, which magnify the magneticsusceptibility of bulk palladium, vanishalmost completely in the palladium nano-grains. Additionally, we could demonstratethat iron impurities play a crucial role inenhancing the magnetic properties of thenanograins and qualify earlier findings offerromagnetism in palladium nanograinswith higher impurity concentrations re-ported by other groups. More precisely,the decrease of the magnetic d-electron

band susceptibility of the palladium nano-grains corresponds with theoretical modelswhich consider the effect of spin-orbitscattering on the magnetic and super-conducting properties of granular, nearlyferromagnetic metals [3]. The weakenedmagnetism of the d-conduction electronsis considered to play a crucial role for theoccurrence of superconductivity in microand nanogranular platinum by adjustingthe balance between electron-phononinteractions and competing magneticinteractions. For this reason, we are nowsearching also for superconductivity inmetal nanoclusters. Also, we have startedto investigate nanoclusters of magneticcompounds, such as magnetite, deposited

on S-layer proteins as promising hybridmaterials for next-generation data storagedevices.

For technological applications of S-layers,the stability of protein and nanoparticlesunder extreme conditions is essential.Unexpectedly, a mutual influence betweenbiological templates and inorganic nano-clusters has been observed. The templateeffectively influences the growth and

spacing of nanoclusters. Vice versa, theinorganic grains stabilize the S-layer. It hasbeen shown that the S-layer of Bacillussphaericus becomes less sensitive to acidicsolutions once it is complexed with PdII+.Usually, proteins irreversibly lose theirnative structural organization when theyare exposed to an acidic environment. S-layers are intrinsically more stable thanmost soluble proteins. Even moresurprising is their gain in stability uponcomplexation with metal ions, allowingthem to withstand very high concen-trations of hydrochloric acid withoutsignificant loss of their structure. Appar-ently, the “clogging” of nanopores andcrevices on the protein surface by metal

ions or metal nanoclusters restricts themotional freedom of the macromoleculesin such a way that they are efficiently heldtogether in their native-like structure. Theirunfolding into random geometries appearsto be inhibited by strong metal proteininteractions. By combining infrared and X-ray absorption spectroscopy, it could beshown that mainly the unusually largenumber of negatively charged carboxylgroups exposed on the S-layer surfaceengages in binding to the positivelycharged metal ions [2]. The electrostaticattraction between these coordinationpartners is the major source of the struc-tural stabilization. This renders metallizedS-layers particularly attractive for technicalapplications where stability at high tem-peratures is required but rarely met by purebiological materials. The insights gainedfrom metal S-layer interactions may help to confer stability to other technically promising proteins by directed muta-genesis as well.

These findings provide an excellent basis atthe FZD for future developments of novelnanomaterials using bacterial self-assem-bling surface-layer (S-layer) proteins incombination with inorganic nanoparticlesas a technology platform.

References[1] Metal binding by bacteria from uranium

mining waste piles and its technological applications, K. Pollmann, J. Raff, M. Merroun, K. Fahmy, S. Selenska-Pobell, Biotechnology Advances 24, 58 – 68 (2006)

[2] Secondary structure and Pd(II) coordination in S-layer proteins from Bacillus sphaericus studied by infrared and X-ray absorption spectroscopy,K. Fahmy, M. Merroun, K. Pollmann, J. Raff, O. Savchuk, C. Hennig, S. Selenska-Pobell, Biophysical Journal 91, 996 – 1007 (2006)

[3] Magnetic properties of transition-metal nanoclusters on a biological substrate, T. Herrmannsdörfer, A.D. Bianchi, T.P. Papageorgiou, F. Pobell, J. Wosnitza, K. Pollmann, M. Merroun, J. Raff, S. Selenska-Pobell, Journal of Magnetism and Magnetic Materials 310, e821 – e823 (2007)

Scheme of metal nanoclusters bound to the S-layer lattice.

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How mineral surfaces retard uranium migration

Vinzenz Brendler, Thuro Arnold, Andreas C. Scheinost, Anke Richter

The migration of uranium from miningareas or nuclear waste disposal areas toground or surface waters poses a severethreat to both man and nature. Therefore,retention mechanisms to prevent themigration and contamination must bethoroughly understood in order to developthe most efficient and economic coun-termeasures. The basic processes—interactions between dissolved (here:radioactive) substances and solid phases—range from the weakest form of retention,i.e., ion exchange, to stronger retentionmechanisms, such as chemisorption,surface precipitation, and formation ofsolid solutions. All processes interact in acomplex pattern, so that only a detailedunderstanding of the interactions at thesolid/liquid interface allows reliable

predictions for uranium migration. Themost basic data to collect are thestoichiometry and the structure of thesurface species. Such information may be determined only by combining spec-troscopy, microscopy, and quantumchemical computations.

Clay rocks are being considered as apossible host rock formation for a futurenuclear waste repository in Germany.Investigating the kinetics, thermodynamics,redox behavior, and speciation of uraniumin this rock formation often requires com-parisons to simpler model systems. Here,gibbsite (γ-Al(OH)3) or silica gel (SiO2) canmimic interactions between actinides andaluminol or silanol surface groups, whereaskaolinite (Al2Si2O5(OH)4) and muscovite(KAl3Si3O10(OH)2) cover both aspects. Inaddition, investigations of iron minerals,e.g., ferrihydrite (Fe2O3 x nH2O), are also

highly interesting because iron corrosionproducts and secondary phases are im-portant components of potential nuclearwaste repositories. Most of these mineralphases show a sorption maximum betweenpH 5 and 8 for uranium(VI). Researchers atthe Institute of Radiochemistry determinedthe basic spectroscopic signal patterns forthe uranium binding onto the above model

Fig. 1: Edge-sharing hexagonal uranyl dimersas found on gibbsite surfaces between pH 5.5and 7.5.

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systems using mainly TRLFS (Time-Resolved Laser-induced FluorescenceSpectroscopy) and EXAFS (Extended X-rayAbsorption Fine Structure). The spectro-scopic fingerprints combined withstructural information gives access to more complicated systems such as mica,feldspars, or clay rocks.

Gibbsite and silica gel: Within a EuropeanCommission ACTINET-6 project withpartners from the Institute for NuclearWaste Disposal at the ForschungszentrumKarlsruhe and the Ecole NationaleSupérieure de Chimie de Paris, weidentified three adsorbed U(VI) surfacespecies on Gibbsite by combining TRLFSand EXAFS. These species were a dimer(Fig. 1), a bidentate inner-sphere surfacecomplex, and a uranium carbonate species.The first two species are fluorescent [1],their fluorescence decay times being330 ±115 ns and 5.6 ±1.6 µs, respectively.The first species dominates the more acidicpH region whereas the second onebecomes gradually more prominenttowards higher pH values. The fluores-cence spectra of both adsorbed uranyl(VI)surface species are red-shifted by 9 nmcompared to the free uranyl cation. Onsilica gel, with TRLFS we observed threeU(VI) surface complexes with fluorescencedecay constants of 47µs, 185µs, and299µs. Peak maxima as a function of pH

are red-shifted by 10 and 16 nm comparedto the free uranyl cation. The spectroscopicfingerprints of these two simplest modelsystems are distinct enough to allow theassignment of binding sites in morecomplex systems (such as mica, feldspars,or clay rocks) to aluminol or silanol sites.

Kaolinite: Collaborating with the Instituteof Nuclear Chemistry at Johannes-Gutenberg-Universität Mainz, we usedEXAFS, XPS (X-ray PhotoelectronSpectroscopy) and TRLFS to study theU(VI) surface complexes on kaolinite inpresence and absence of humic acid (HA).Two uranyl surface species with fluores-cence decay times of 5.9 ± 0.7 and 42.5 ±1.7 µs as well as 4.4 ± 0.6 and30.9 ± 3.6 µs were identified in the binary(U(VI)-kaolinite) and ternary system(U(VI)-HA-kaolinite), respectively. Clearly,aluminol binding sites control the sorptionof U(VI) onto kaolinite. In the binarysystem, both surface species can beattributed to adsorbed bidentate mono-nuclear surface complexes, which differ inthe number of water molecules in theircoordination environment. In the ternarysystem, U(VI) prefers direct binding tokaolinite rather than via humic acid, but itis sorbed as a uranyl-humate complex.Thus, the hydration shell of the U(VI)surface complexes is partly displaced withcomplexed humic acid, which is distributed

between kaolinite particles. Humic acidweakens the retention of uranyl in theneutral pH range, but enforces sorptionunder more acidic or alkaline conditions.

Muscovite: In cooperation with theDepartment of Geological Sciences at theUniversity of Michigan (Ann Arbor, USA)we applied TRLFS and HAADF-STEM(High-Angle Annular Dark-Field ScanningTransmission Electron Microscopy) in orderto investigate the species of uranyl(VI)adsorbed onto muscovite [2]. HAADF-STEM revealed that nano-clusters of anamorphous uranium phase were attachedto the edge-surfaces, but not to {001}cleavage planes of muscovite (Fig. 2),given the main surface site alternatives.TRLFS provided evidence of the presenceof two adsorbed uranium(VI) species onthese edge-surfaces. The species with theshorter fluorescence lifetimes are inter-preted as truly adsorbed bidentate surfacecomplexes, in which the U(VI) binds to thealuminol groups of the edge-surfaces. Thesurface species with the longer fluores-cence lifetimes are interpreted to be nano-sized clusters of polynuclear uranyl(VI)surface species with a particle diameter of1 to 2 nm. These species are intermediateproducts which are eventually transformedinto irreversibly-retarded surface precipi-tations.

Fig. 2: U(VI) sorption onto muscovite: Possible surface sites as structural concept and visualizedby Scanning Electron Microscopy (SEM).

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Ferrihydrite: To estimate the mobility ofU(VI), we determined the mechanism ofU-uptake by fresh precipitates and themolecular structure of U bonding. Weemployed EXAFS spectroscopy at the Fe K-edge and the U LIII-edge as well asAttenuated Total Reflectance FourierTransform Infrared (ATR-FTIR) spectros-copy [3]. Freshly formed precipitates wereidentified as colloidal two-line ferrihydrite.They removed U(VI) from the solution bysorption processes, while surface precipi-tation or structural incorporation of U wasnot observed. By employing a novel EXAFSanalysis method, the Monte Carlo TargetTransformation Factor Analysis, we couldascertain for the first time a 3D con-figuration of this sorption with a slightlytilted position of the adsorbed UO2

2+ unitrelative to the edge-sharing Fe(O,OH)6

octahedra. In the presence of dissolvedcarbonate and at pH 8.0, a distalcarbonate O-atom at 4.3 Å supports theformation of ternary U(VI)-carbonatosurface complexes, which was confirmedby ATR-FTIR. However, in slightly acidicconditions (pH 5–6) in an equilibrium with

atmospheric CO2, the U(VI) sorption onferrihydrite was dominated by the binarycomplex species -Fe(O)2=UO2, whereasternary U(VI)-carbonato surface complexeswere less relevant. While sulfate andsilicate were also present in the minewater, they had no detectable influence onU(VI) surface complexation. Our experi-ments demonstrate that U(VI) forms stableinner-sphere sorption complexes even inthe presence of carbonate and at slightlyalkaline pH conditions which have pre-viously been assumed to greatly acceleratethe mobility of U(VI) in aqueous envi-ronments.

The improved understanding of basicsorption processes, and in particular anyindependent spectroscopic evidence ofsurface species that so far has been onlypostulated, significantly helps to transferthe use of surface complexation modelsfrom science into real-world applications.Thermodynamic sorption databases suchas RES3T—Rossendorf Expert System forSurface and Sorption Thermodynamicsfunded by the German Federal Ministry ofEconomics and Technology (Fig. 3)—andtheir application toward uncertaintyanalysis and blind prediction modeling [4]increase the reliability and trustworthinessof the surface complexation models. RES3Tis the first and largest mineral-specificsorption database worldwide, currentlycovering 117 minerals and 130 ligands,providing 3520 surface complexationconstants based on 2170 bibliographicreferences. More than 100 users from 16countries indicate the high demand forsuch a tool. The database also offers directadvantages in interpreting reactivetransport experiments, as demonstratedtogether with the Laboratory for WasteManagement at the Paul-Scherrer-Institutin Switzerland [5].

References[1] Uranyl sorption onto gibbsite studied

by time-resolved laser-induced fluorescence spectroscopy (TRLFS),N. Baumann, V. Brendler, T. Arnold, G. Geipel, G. Bernhard, Journal of Colloid and Interface Science 290, 318 – 324 (2005)

[2] Adsorbed U(VI) Surface Species on Muscovite Identified by Laser Fluorescence Spectroscopy and Trans-mission Electron Microscopy, T. Arnold, S. Utsunomiya1, G. Geipel, R.C. Ewing1, N. Baumann, V. Brendler, Environmental Science & Technology 40, 4646 – 4652 (2006)

[3] Molecular characterization of uranium(VI) sorption complexes on iron(III)-rich acid mine water colloids,K.-U. Ulrich, A. Rossberg, H. Foersten-dorf, H. Zänker, A.C. Scheinost, Geochimica et Cosmochimica Acta 70, 5469 – 5487 (2006)

[4] Blind Prediction of Cu(II) Sorption onto Goethite: Current Capabilities of Surface Complexation Modeling, A. Richter, V. Brendler, C. Nebelung, Geochimica et Cosmochimica Acta 69, 2725 – 2734 (2005)

[5] Laboratory Column Experiments on the Migration of Uranium (IV)/(VI) in the Presence of Humic Acids in Quartz Sand,J. Mibus, S. Sachs, W. Pfingsten2, C. Nebelung, G. Bernhard, Journal of Contaminant Hydrology 89, 199 – 217 (2007)

Project partners1University of Michigan, Dept. Geological Sciences, Ann Arbor, USA

2Paul-Scherrer-Institut, Laboratory for Waste Management, Villigen, Switzerland

3Institute for Nuclear Waste Disposal, Forschungszentrum Karlsruhe, Germany

4Ecole Nationale Supérieure de Chimie de Paris, France

5Institute of Nuclear Chemistry, Johannes-Gutenberg-Universität, Mainz, Germany

Fig. 3: Start menu of the mineral-specific sorptiondatabase RES3T.

31

Environmental impact of depleted uranium

Gerhard Geipel, Nils Baumann, Thuro Arnold

The contamination of cultivated areas byuranium in the past is mainly connected to four human activities. Firstly, low-levelconcentrations of uranium are distributedover large areas by using phosphatefertilizers in agriculture. Secondly, uraniummining and milling has caused uraniumcontaminations close to residential areas,especially in Germany. The third source ofenvironmental pollution with uranium andradioactive products is connected tonuclear industry by accidents in powerstations and processing plants. Last but notleast, uranium is used by the military, thuscontributing to the distribution of thisheavy metal in the environment. Depleteduranium (DU), a byproduct of theenriching process in the production ofnuclear fuel, has been used as armor-piercing ammunition in several past wars.Many of these projectiles did not explodecompletely and residues of the uraniumcontained in them corrode in the soil. Thiscould be the origin of toxic uranium indrinking water or in agricultural plants. As a consequence, uranium could betransferred into the human food chain.Possible risks for human health havetriggered research on the geochemicalbehavior of DU in nature includingtransport and immobilization in the soil.

Uranium in its main oxidation states (+4, +5, and +6) shows luminescenceproperties. Especially in the +6 oxidationstate, the stable form under normalenvironmental conditions, the lumi-nescence of dissolved, solid, or surfacespecies works as a fingerprint to determinethe binding forms of uranium [1, 2]. In the past, time-resolved laser-induced

fluorescence spectroscopy (TRLFS) hasbeen continually developed. This includescryogenic techniques as well as theexcitation of the species at differentwavelengths, leading to extremely lowdetection limits for the several bindingforms. In addition, luminescence datasetsthat have been collected for most of theuranium binding forms are the basis forfast and correct determination of uraniumspecies.

Uranium ammunition meets dissolved fertilizerWe cooperated with British scientists fromthe group of Prof. David Read (Enterprise,University of Reading and University ofAberdeen) on a study in which discs ofdepleted uranium (25 mm diameter,0.5 mm thickness) obtained from a pristineBritish military tank shell (Fig. 1) [3] wereplaced in a low-concentration, well-defined solution of calcium and phosphateand kept there at 24 °C for about half ayear. The pH-value of this solution wasadjusted to an initial value of 6.0. Itgradually decreased to about pH 5.2 bythe end of the experiment. The solutionconcentration of calcium, phosphate, anduranium as well as the pH-value weremonitored during the whole experiment.

TRLFS measurements on the surface of thesample were carried out and comparedwith measurements conducted at the sameconditions (laser energy, gate width) on anunaltered DU disc, the so-called “blank”,which was not in contact with the Ca-Psolution described above. The acquiredTRLFS spectra showed six distinct emissionbands at 486, 501, 522, 546, and 601nanometers (Fig. 2), a pattern typical ofU(VI). The fluorescence lifetimes werecalculated as 50 ± 5 and 700 ± 25 ns.

The shorter lifetime of 50 ± 5 ns wasinterpreted as a result of the inhomo-geneity and disturbances in the crystallattice on the surface. The observed redshift towards higher wavelengths com-pared to the spectra of the so-called freeuranyl in water (UO2

2+(aq)) is mostlyindicative of uranyl binding forms. As thecontact solution contains phosphate ions,the fluorescence spectra of the U(VI) phaseon DU were compared with TRLFS datafrom well-known U-phosphates. Corres-ponding uranyl phosphate minerals wereprovided courtesy of the mineral collectionof the TU Bergakademie Freiberg [4].

By far the best match among the spectrameasured on altered DU was found for thespectra of a natural mineral meta-autunite,Ca(UO2)2(PO4)2 x (H2O)8 (Fig. 2). Here, wefound the best agreement in peak maxima,peak height ratios, and in the lifetimes ofthe fluorescence signals. So far, evidencefor the formation and the identification ofsuch a thin mineral layer could only beobtained with the analytical method ofTRLFS.

Fig. 1: Experiments with dissolved fertilizers –DU sample and “blank”.

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Corrosion of expended uraniumammunition in soilThe experiment described above was ableto show the behavior of DU in a solutionof a phosphate fertilizer. While this referredto well-defined laboratory conditions,periods of rain and dryness alternate undernatural conditions, which can be simulatedby lysimeter experiments. At the Instituteof Radiation Protection at the GSF-National Research Center for Environmentand Health, the corrosion and leaching ofdepleted uranium (DU) was investigatedfor three years using six DU munitions(Fig. 3), each buried in a column with a soil core [5]. The first soil was made up ofa sandy-loamy brown earth whereas thesecond soil consisted of a silty-loamyparabrown earth. The columns wereinstalled in an air-conditioned laboratoryand were weekly irrigated with 16 mmsynthetic rainwater of pH 6.

On average, 7.9% of the initial DU masswas corroded after three years, indicatingan acceleration of corrosion compared tothe first year. The leaching rates increasedstronger than the corrosion by a factor ofmore than 100, resulting in a mean totalamount of leached 238U of 13 mg ascompared to 0.03 mg after the first year.The uranium binding forms present in theseepage water were predominantlyhydroxo compounds such as (UO2)3(OH)5

+

or carbonate compounds such asUO2(CO3)3

4- (Fig. 4). Due to evapotrans-piration and depending on the position ofthe ammunition, upward flows of U wereobserved in all columns, but with differentextents. During the second year, in thecolumns in which the DU was in topposition, yellow material crystallized out at the soil surface. Speciation analyses bymeans of TRLFS revealed that in the yellowmaterial, mainly phosphate species ofuranium were present (Fig. 5), probablyAlH(UO2)4(PO4)4 x 16(H2O) (sabugalite) or alternatively Ca(UO2)2(PO4)2 x 10-12(H2O) (autunite). In the corrodedmaterial of the munitions, other phosphatespecies such as UO2HPO4 were found.Interestingly, the uranium complexes in the seepage water do not seem to be thesame as in the corroded mass and thecrystallized material at the soil surface,

Fig. 2: Conformitybetween the fluorescencespectra of the mineral layergenerated on DU with thespectra of meta-autunite.

Fig. 3: Part of a DUpenetrator after corrodingfor three years.

Fig. 5: Comparison of theluminescence spectrum of a solid sample of the yellowmaterial crystallized out atthe soil surface with thespectrum of sabugaliteAlH(UO2)4(PO4)4 x 16(H2O).

Fig. 4: Comparison of theluminescence spectrum ofa liquid sample of theseepage water with thespectrum of UO2(CO3)3

4-.

32

33

References[1] Some aspects of actinide speciation by

laser-induced spectroscopy, G. Geipel, Coordination Chemistry Reviews 250, 844 – 854 (2006)

[2] Speciation of actinides (environmental, food, clinical, occupational, health),G. Geipel, in: Handbook of Elemental Speciation II, R. Cornelis (ed.), Wiley & Sons Ltd., London, 2005, pp. 509 – 563

[3] Detection of U(VI) on the surface of altered depleted uranium by time-resolved laser-induced fluorescence spectroscopy (TRLFS), N. Baumann, T. Arnold, G. Geipel, E.R. Trueman1, S. Black1, D. Read1, Science of the Total Environment 366, 905 – 909 (2006)

[4] Spectroscopic properties of uranium(VI) minerals studied by time-resolved laser-induced fluorescence spectroscopy (TRLFS), G. Geipel, G. Bernhard, M. Rutsch, V. Brendler, H. Nitsche, Radiochimica Acta 88, 757 – 762 (2000)

[5] Long-term corrosion and leaching of depleted uranium (DU) in the soil,W. Schimmack2, U. Gerstmann2, W. Schultz2, G. Geipel, Radiation and Environmental Biophysics 46, 221 – 227 (2007)

Project partners1University of Reading, United Kingdom2Institute of Radiation Protection, GSF-National Research Center for Environment and Health, Neuherberg, Germany

3Institute of Mineralogy, Technische Universität Bergakademie Freiberg, Germany

respectively. It was concluded that thedramatic increase in leaching and its largetemporal and spatial variability do notallow any extrapolation into the future.However, the high level of the uraniumconcentrations in the seepage waterrequires additional investigation about thetransport of uranium through the soil. In sodoing, the concentration of uranium fromDU munitions in the groundwater in areasaffected by DU weapons can be estimated.

There is no other analytical method thatcould deliver comparable results. It can beconcluded that under the circumstances

described here, the dissolving process ofuranium projectiles is connected to theformation of phosphate-containingsecondary minerals. The mobility of DUoriginating from projectiles is defined bydissolving processes from the emergingsecondary mineral phase. With thisexemplary investigation, the Institute ofRadiochemistry was able to show thatinteractions between DU ammunition with water and soil, i.e., the reactionmechanism, can be clarified. However, atthis stage, predictions can only be madewith great caution!

Rossendorf Beamline


Structure of Matter

Life Sciences


PET Center

Ion Beam Center


Naturally accruing meta-autunite sample from the Technische Universität Bergakademie Freibergmineral collection.


34

XAFS investigation of actinide speciesunder controlled redox conditions

Christoph Hennig, Katja Schmeide, Atsushi Ikeda, Jürgen Claußner, Andreas C. Scheinost

Natural aquatic and terrestrial environ-ments exert wide variations in redox statedue to oxygen diffusion and microbialprocesses. Actinides, with their differentoxidation states, are especially susceptibleto these redox changes, forming a varietyof dissolved complexes which may greatlydiffer in solubility and mobility. Thesecomplexes are often difficult to investigatedue to their thermodynamic metastability.This problem can be solved by using anelectrochemical cell, which allows tocontrol and stabilize the redox conditions.We therefore developed such a cell (Fig. 1)for in-situ X-ray absorption spectroscopyat the Rossendorf Beamline (ESRF, Gre-noble, France). The cell comprises a doublecompartment against radionuclide release,electrodes for electrolysis, and sensors fortemperature, pH, and Eh measurements.

Fig. 2 shows the reduction process ofuranium(VI) in a formic acid solution. An X-ray absorption near-edge structure(XANES) spectrum was obtained every 30 minutes without interrupting theelectrolysis. The stepwise change of thespectral features shows the formation of uranium(IV). A quantitative analysis ofthe spectra reveals the reduction kinetics of U(VI), indicating that the process iscompleted after about five hours. Whilemaintaining the redox potential at the finallevel, extended X-ray absorption finestructure (EXAFS) measurements are thenperformed to determine the structure ofthe complexes.

Fig. 1: Spectroelectrochemical cell for X-ray absorption spectroscopy.

Fig. 2: Left side: U LIII-edge XANES spectra obtained during the reduction of 0.01 M UO22+ in 0.2 M

formic acid. The reduction was performed at a constant potential of –350 mV vs. Ag/AgCl. Right side: Species distribution as function of electrolysis progress.

35

Fig. 3 shows the structure of U(IV) sulfatein aqueous solution as elucidated by EXAFSspectroscopy. The pure U(IV) hydrate iscoordinated by nine water molecules witha U-O distance of 2.40 Å. The spectrum ofU(IV) sulfate comprises two additionalpeaks at 3.08 Å and 3.67 Å, indicative ofbidentate and monodentate sulfategroups, respectively [2]. The monodentate

coordination generally prevails at low[SO4

2-]/[U(IV)] ratios, whereas thebidentate coordination becomes moreimportant at higher sulfate concentrations.

The spectroelectrochemical cell is used tostudy actinides under controlled redoxconditions to simulate the geochemicalsituation in former uranium mines and

potential nuclear waste repositories. Thedevelopment of this new experimentaltechnique was fundamental for severalinternational projects [3-8] funded by theEuropean ACTINET Network of Excellenceand the German Research Foundation(DFG) (HE 2297/2-1).

Rossendorf Beamline


Structure of Matter

Life Sciences


PET Center

Ion Beam Center


Fig. 3: Fourier transformed k3 weighted EXAFS of the U LIII-edge of U(IV) sulfate with 0.05 M U(IV) and 0.4 M SO42- at pH 1.

References[1] Comparative EXAFS investigation of

uranium(VI) and -(IV) aquo chloro complexes in solution using a newly developed spectroelectrochemical cell,C. Hennig, J. Tutschku, A. Rossberg, G. Bernhard, A.C. Scheinost, Inorganic Chemistry 44, 6655 (2005)

[2] EXAFS investigation of U(VI), U(IV) and Th(IV) sulfato complexes in aqueous solution, C. Hennig, K. Schmeide, V. Brendler, H. Moll, S. Tsushima, A.C. Scheinost, Inorganic Chemistry, 46, 5882 (2007)

[3] First structural characterization of a protactinium(V) single oxo bond in aqueous media, C. Le Naour1, D. Trubert1,

M.V. Di Giandomenico1, C. Fillaux2, C. Den Auwer2, P. Moisy2, C. Hennig, Inorganic Chemistry 44, 9542 (2005)

[4] Speciation of technetium and rhenium complexes by in situ XAS-electro-chemistry, F. Poineau3, M. Fattahi3, C. Den Auwer2, C. Hennig, B. Grambow3, Radiochimica Acta 94, 283 (2006)

[5] Comparative study of uranyl(VI) and -(V) carbonato complexes in an aqueous solution, A. Ikeda, C. Hennig, S. Tsushima,K. Takao4, Y. Ikeda4, A.C. Scheinost,

G. Bernhard, Inorganic Chemistry 46, 4212 (2007)

[6] Evidence for double-electron excitations in the L3-edge X-ray absorption spectra

of actinides, C. Hennig, Physical Review B 75, 035120 (2007)

[7] The relationship of monodentate and bidentate coordinated uranium(VI) sulfate in aqueous solution, C. Hennig, A. Ikeda, K. Schmeide, V. Brendler,H. Moll, S. Tsushima, A.C. Scheinost, S. Skantha-kumar5, R. Wilson5, L. Soderholm5, K. Ser-vaes5, C. Görrler-Walrand6, R. Van Deun6, Radiochimica Acta, submitted

[8] Species distribution and coordination of uranyl chloro complexes in acetonitrile,C. Hennig, K. Servaes6, P. Nockemann6, K. Van Hecke6, L. Van Meervelt6, J. Wouters6, C. Görller-Walrand6, R. Van Deun6, Inorganic Chemistry, submitted

Project partners1Centre National de la Recherche Scientifique, Institut de Physique Nucléaire, Orsay, France

2Commissariat à l’Energie Atomique Marcoule, Bagnols sur Cèze, France

3SUBATECH, Université de Nantes, Ecole des Mines, Nantes, France

4Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Japan

5Chemistry Division, Argonne National Laboratory, Argonne, USA

6Department of Chemistry, Katholieke Universiteit Leuven, Belgium

FACTS & FIGURES

37

The Forschungszentrum Dresden-Rossendorf (FZD) is a multi-disciplinary research centerfor natural sciences and technology. It is the largest institute of the Leibniz Associationand is equally funded by the Federal Republic of Germany and the Federal States, inparticular by the Free State of Saxony. At the FZD, around 225 scientists are engaged inthree different research programs of basic and application-oriented research. Scientistsworking in the Structure of Matter program investigate the reactions of matter wheninfluenced by high fields and minuscule dimensions. Research and development in theLife Sciences program is focused on the imaging of tumors and the effective radiationtreatment of cancer. How can humankind and the environment be protected fromtechnical risks? – This question is in the center of research in the Environment and Safetyprogram of the FZD.

In the following Facts & Figures section data presenting the scientific output in theEnvironment and Safety research program are given as well as information on staff andfunding at the FZD.

Facts & Figures

2004 2005 2006

Research Programs

Structure of Matter

Life Sciences


Facilities

Sum

Public FundingT€

13.858

8.241

13.005

20.721

55.825

Project FundingT€

1.190

801

3.180

911

6.082

Public FundingT€

14.209

6.266

12.950

20.428

53.853

Project FundingT€

1.259

645

3.656

756

6.316

Public FundingT€

19.575

8.191

11.866

17.988

57.620

Project FundingT€

1.405

784

3.990

1.643

7.822

Structure of Matter Life Sciences Environment and Safety

10

8

6

4

2

02004 2005 2006

160

140

120

100

80

60

40

20

02004 2005 2006

Patents

Publications

staff scientists third-party funded scientistsguest scientists postdocs

50

40

30

20

10

02004 2005 2006

Scientific staff

Budget

This figure shows the number of applications for a patent filed in eachresearch program of the FZD during the last years. National andinternational applications for a patent of one and the same inventionare only counted once.

This chart displays the evolution of peer-reviewed articles by scientistsfrom the FZD’s Environment and Safety program. The figure includesreviewed proceedings (2004: 39, 2005: 50, 2006: 53).

This table displays the share of each research program as well as the experimental facilities located at the FZD of both public and projectfunding during the last three years.

This chart shows the evolution of posts occupied by scientificpersonnel in the Environment and Safety program of the FZD. Third-party funded scientists, guest scientists, and postdocsrepresented by the corresponding figures are given in units ofpaid full-time posts.

38

Latvia

India

Hungary

Algeria

Japan

Israel

Spain

USA

Romania

Australia

other

5

5

3

3

36

13

10

9

8

6

5

Russia

Ukraine

Bulgaria

Czech Republic

Poland

China

99

29

25

22

19

16

80

60

40

20

02004 2005 2006

Doctoral students

International guest scientists

This figure shows the evolution of the doctoral students atthe FZD from 2004 until 2006.

Here, the distribution of the international guest scientistswho visited the FZD for the purpose of research between2004 and 2006 is shown according to their countries oforigin.

39

FACTS & FIGURES

40

Structure of Matter

Life Sciences

Research Technology

Dr. Frank Herbrand

Administration

Andrea Runow

Technical Service

Dr. Wolfgang Matz

Institute of Ion Beam Physics andMaterials Research

Prof. W. Möller and Prof. M. Helm

Institute of Radiopharmacy

Prof. Jörg Steinbach

Dresden High Magnetic FieldLaboratory

Prof. Joachim Wosnitza

Institute of Radiation Physics

N.N.

Laser-Particle Acceleration

Dr. Ulrich Schramm


Institute of Safety Research

Prof. Frank-Peter Weiß

Institute of Radiochemistry

Prof. Gert Bernhard

General Assembly

Scientific Advisory Board Chair: Prof. August Schubiger

Supervisory BoardChairman: Dr. Gerd UhlmannDeputy: Dr. Jan Grapentin

Scientific Technical Council Chair: Prof. Frank-Peter Weiß

Works Committee Chair: Siegfried Dienel

Support Staff

Board of Directors Scientific Director Administrative DirectorProf. Roland Sauerbrey Dr. Dr. h. c. Peter Joehnk

Organizational Chart

IMPRINT

FZD Triennial Scientific Report 2004-2007 I Volume 2Volume 1 Structure of MatterVolume 2 Environment and SafetyVolume 3 Life Sciences

Published by Forschungszentrum Dresden-RossendorfConcept and editorial work Dr. Christine Bohnet & Anja Bartho, FZDDesign and layout WA Preußel, CoswigPhotos C. Preußel & FZD employeesAvailable from Forschungszentrum Dresden-Rossendorf

Public RelationsBautzner Landstr. 12801328 Dresden / GermanyPhone: +49 351 260 2450Email: [email protected]://www.fzd.de

ISSN 1437-322XWissenschaftlich-Technische BerichteFZD-471, October 2007

Copying is welcomed, provided the source is quoted.

Forschungszentrum Dresden-RossendorfP.O. Box 51 01 19 I 01314 Dresden/GermanyScientific Director I Prof. Dr. Roland SauerbreyPhone +49 351 260 2625Fax +49 351 260 2700Email [email protected]

Member of the Leibniz Association

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