Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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31745 Publications
Solitonische Feldkonfigurationen des Nambu & Jona-Lasinio-Modells im Medium
Schleif, M.;
  • Open Access LogoForschungszentrum Rossendorf; FZR-211

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Publ.-Id: 1126 - Permalink


Kühlmittelvermischung in Druckwasserreaktoren; Vergleich von Kühlmittelströmung und -vermischung in einem skalierten Modell des DWR Konvoi mit den Vorgängen im Originalreaktor; Rechnungen mit dem CFD-Code CFX 4.1
Höhne, T.;
Es ergab sich die Notwendigkeit, die Vermischungseffekte mit einem 1:5 skalierten Modell nachzuvollziehen. In dieser Arbeit wurden Skalierungseffekte hervorgehoben und ein Vergleich der Strömungen im Originalreaktor und 1:5 Plexiglasmodell mit Hilfe eines numerischen Strömungsberechnungsprogrammes vollzogen. Dabei wurde das Modell und der Originalreaktor möglichtst originalgetreu abgebildet und mit den kalten Strängen zusammen modelliert.Die Vergleichsrechnungen belegen, daß es ausreichend ist, die Vermischungsvorgänge in einem mindestens 1:6.6 skalierten Modell eines DWR zu untersuchen. Die Parameter (Druck, Temperatur, Geschwindigkeit) erlauben den Aufbau als Plexiglasmodell, das eine optische Beobachtung der Vermischung ermöglicht. Das Forschungszentrum Rossendorf hat mit dem Aufbau eines 1:5 Modells 1997 begonnen.
  • Open Access LogoForschungszentrum Rossendorf; FZR-210 September 1997

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Publ.-Id: 1125 - Permalink


Utilization of Plasma Source Ion Implantation for Tribological Applications
Günzel, R.; Brutscher, J.; Mändl, S.; Möller, W.;
  • Surface & Coatings Technology 96 (1997) pp. 16-21

Publ.-Id: 1124 - Permalink


Synthesis and Crystal Structure of Novel Tetrameric Nitrido Complexes
Griffith, D. V.; Parrott, J.; Togrou, M.; Dilworth, J. R.; Zheng, Y.; Ritter, S.; Abram, U.;
  • Zeitschrift für anorganische und allgemeine Chemie 624 (1998) 1409-1414

Publ.-Id: 1123 - Permalink


Particle emission from UV-irradiated silica surfaces
Rettig, D.; Merker, P.; Nitsche, H.;
  • Journal of Aerosol Science Vol.29, Suppl.1, pp. S921-S922 (1998)
  • Lecture (Conference)
    5th International Aerosol Conference, Edinburgh, 12-18.Sept.,1998

Publ.-Id: 1122 - Permalink


Determination of Molecular-Level Structural Information of Uranium in Environmentally Relevant Samples by EXAFS
Roßberg, A.; Denecke, M. A.; Reich, T.; Hennig, C.; Nitsche, H.;
  • Poster
    Konferenz Uran-Bergbau und Hydrogeologie II, Freiberg, Germany, 15.-17.09.1998
  • Poster
    Euroconference and NEA Workshop: Actinide-XAS-98, Grenoble, France, 04.-06.10.1998

Publ.-Id: 1120 - Permalink


Operation Conditions of the Emergency Condenser of the SWR1000
Schaffrath, A.; Hicken, E. F.; Jaegers, H.; Prasser, H.-M.;
The Siemens AG is developing the innovative boiling water reactor concept SWR1000. New features are the passive safety systems (e.g. emergency condensers, building condensers, passive pressure pulse transmitters).

For the experimental investigation of the emergency condenser effectiveness, the NOKO test facility has been constructed at the Forschungszentrum Jülich. The facility has an operating pressure of 10 MPa and a maxi-mum power of 4 MW. The emergency condenser bundle consists of eight tubes and is fabricated with planned geometry and material of the SWR1000. In more than 200 experiments, the emergency condenser capacity was determined as a function of pressure, water level and concentration of noncondensables in the pressure vessel as well of pressure, water level and temperature in the condenser.

For the evaluation of the NOKO experiments, the program system CASH-Graphics (Computergestützte Auswertung und Unsicherheitsanalyse) was developed. This evaluation is the basis for the determination of the operation conditions of the emergency condenser.

Post test calculations of NOKO experiments were per-formed with an improved version of ATHLET. To calculate the heat transfer coefficients during condensation in horizontal tubes the module KONWAR has been developed and implemented in ATHLET. KONWAR is based on the flow regime map of Tandon and includes several semi-empirical correlations for the determination of the heat transfer coefficients. The comparison between calculations and experiments shows a good agreement.

Keywords: SWR1000, ATHLET, emergency condenser, KONWAR, operation conditions
  • Nuclear Engineering and Design 188 (1999), p. 303-318

Publ.-Id: 1119 - Permalink


Ein modernes technisches System zur verbesserten betrieblichen Überwachung des ukrainischen Kernkraftwerks Saporoshje
Beyer, M.; Carl, H.; Schumann, P.; Seidel, A.; Weiß, F.-P.; Zschau, J.; Nowak, K.;
Die zu Beginn der neunziger Jahre in der Ukraine praktizierte KKW-Überwachung ermöglichte der Aufsichtsbehörde nur einen unzureichenden Zugang zu Informationen über den jeweils aktuellen betrieblichen Sicherheitszustand. Im Zusammenhang mit den Ergebnissen von Sicherheitsanalysen für Kernkraftwerke war es daher erforderlich, die Möglichkeiten der betrieblichen Überwachung dieser KKW durch die ukrainische Behörde zu verbessern. Für das KKW Saporoshje wurde vom Forschungszentrum Rossendorf im Verbund mit dem TÜV Rheinland ein modernes Überwachungssystem als Pilotprojekt konzipiert, eingerichtet und Ende 1995 in den Probebetrieb überführt. Es ergänzt die vorhandenen betrieblichen Kontroll- und Überwachungseinrichtungen durch Einbeziehung moderner Informations- und Rechentechnik. Das System ermöglicht eine kontinuierliche Beobachtung des Zustandes der Anlage im Normalbetrieb und bei Betriebsstörungen bzw. Störfällen, so daß bei erkennbaren Abweichungen vom bestimmungsgemäßen Betrieb frühzeitig durch Anfrage und Anordnung darauf reagiert werden kann.
  • Atomwirtschaft Atomtechnik 4 April 1998, S. 230-234

Publ.-Id: 1118 - Permalink


Einfluß von Grubenholzabbauprodukten auf die Redoxsituation in Flutungswässern und auf das Sorptionsverhältnis von Eisen und Uran an Erzgebirgsmetamorphiten und Elbtalsedimenten
Abraham, A.; Mack, B.; Antje, B.; Nitsche, H.;

Die Untersuchungen zur Sorption von Eisen und Uran unter Wahrung von Grubenbedingungen bezüglich Wasserbeschaffenheit und pH-Wert wurden an typischen Gesteinen und Mineralien des Westerzgebirges wie Phyllit, Granit, Gneis, Diabas und Calcit sowie an den Königsteiner Elbtalsedimenten Sandstein, Tonstein, Pläner und Pläneräquivalent durchgeführt. Dabei wurde die Sorption unter aeroben und anaeroben Bedingungen verglichen.

Neben hydrogeochemischen Prozessen, wie z.B. der Pyritoxidation, trägt auch das Holzinventar in den Gruben und die in der Wechselwirkung mit dem Grubenwasser entstehenden Holzabbauprodukte zur Sauerstoffzehrung und damit zur Veränderung der Redoxsituation bei. Es werden reduzierende Bedingungen bezüglich Eisen(III) und Uran(VI) ausgelöst. Mittels elektrochemischer und spektrophotometrischer Methoden wurden Prozesse der Eisen(III)- und Uran(VI)-Reduktion in Langzeituntersuchungen charakterisiert.

In die Untersuchungen wurden hydrothermale Grubenholzauszüge und Fichtenholzlignine, die im Institut für Pflanzen- und Holzchemie, Tharandt präpariert wurden, einbezogen [1]. Die Sorptionsuntersuchungen an den Erzgebirgsmetamorphiten wurden aus den typischen neutralen, calcitgesättigten und sulfatreichen Gruben- und Flutungswässern, wie sie im Schlemaer Revier auftreten, vorgenommen. Im Falle der Königsteinsedimente wurde eine Wasserzusammensetzung gewählt, wie sie im Flutungsendstadium der Grube zu erwarten wäre, d.h. nach Auffüllung der in den gelaugten Sedimenten verbliebenen Lösungsrückstände mit Grundwasser [2].

Die Verteilungsverhältnisse wurden in grubenrelevanten Konzentrationsbereichen mittels batch-Technik unter Einsatz von Radiotracern (44,6 d 59Fe; 2,45∙105 a 234U) und der Flüssigszintillationsmessung bestimmt.

  • Poster
    International Conference and Workshop on Uranium Mining and Hydrogeology II, Freiberg, Germany, September 15-17, 1998

Publ.-Id: 1117 - Permalink


Hydrothermal Wood Decomposition and Influence of the Degradation Products on the Uranium Adsorption on Metamorphic Rocks and Sediments
Baraniak, L.; Jelen, K.; Schiene, R.; Fischer, K.; Bernhard, G.; Nitsche, H.;

The influence of mine-wood leachates on the uranium(VI) adsorption (1) on typical rocks and minerals of the ore mountains mining sites and (2) on sediments of the Königstein mine (Saxony) and its near field was studied under aerobic condition.

Wood decomposition was carried out by boiling of shavings with water under reflux. The leachate were analysed regarding DOC, phenolic and saccharic compounds, molecular weight distribution and content of carboxylic and phenolic hydroxyl groups.

The adsorption experiments were carried out by a 4-6 weeks equilibration of the geomaterial with the aqueous phase in the presence of U(VI) and DOC. The uranium concentration ranged from 3.2∙10-6 to 3.2∙10-5 mol/L (0.76-7.62 mg/L) and the DOC content was 8.3-166 mg/L. The distribution ratio (Rs [mL/g]) was determined from liquid scintillation counting of the added 234U tracer (10-40 Bq/sample) after distribution and a careful phase separation.

Uranium adsorption behaviour at the ore mountains rocks and minerals: The adsorption from a DOC-free synthetic mine water takes mainly place at diabase (Rs=4.8 mL/g) and calcite (Rs=4.5); about 80% of the uranium is bound on this minerals. The adsorption under the influence of the wood degradation products and pine wood lignin (PWL) is increased to 90-95 % (calcite: Rs=13.0/108 mL/g; diabase: Rs= 9.9/59). Granite and basalt adsorb from DOC-free mine water 50-60% of the uranium (Rs=0.97/1.6). In the presence of the wood leachate and lignin the adsorption increases to about 80% (granite: Rs=6.5/15.5; basalt: Rs=5.9/18.5). In the case of gneiss the effect of the wood leachate and lignin is not so significant (Rs: 1.1-1.5). The uranium adsorption on phyllite takes place to a much lower level. From all solutions practically no uranium is bound (Rs≤ 0.1), i.e., uranium adsorption is smaller than 2%.

Uranium adsorption behavior at the Königstein sediments: It is evident that uranium is prefferently bound to sandstone (91-97%); especially with a high distribution ratio to the limonithe-rich turonian sandstone (142 mL/g). Even under the influence of the organic compounds the sorption ranges from 68 to 93% (Rs: 10-70). A sorption degrease is caused by the wood leachate and lignin (2-4%). The level of adsorption on lime marl is much lower (22-68%, Rs: 1.4-11). The wood leachate and the lignin enhance the adsorption by 10-20%. The studied claystone, in general, was not able to bind uranium. Only in the presence of the wood leachate about one third of the uranium is adsorbed (Rs= 2.9). The reason may be that this sediment acidifies the aqueous phase (from pH 7.3 to 3.5) and some of the DOC with part of the uranium is precipitated on the sediment.

As a general tendency it can be seen that the strongly polymer wood breakdown substances strengthen the uranium(VI) adsorption at the geomaterials from the typical mine waters.

  • Poster
    International Conference and Workshop on Uranium Mining and Hydrogeology II, Freiberg, Germany, September 15-17, 1998

Publ.-Id: 1116 - Permalink


Speziation des Urans- Bestimmung und Berechnung unter natürlichen Bedingungen
Geipel, G.; Rutsch, M.; Bernhard, G.; Brendler, V.; Nitsche, H.;
  • Lecture (Conference)
    Uran Konferenz Freiberg 1998

Publ.-Id: 1115 - Permalink


Coupling Geochemical Speciation to Risk Assessment Codes
Brendler, V.; Bernhard, G.; Nitsche, H.; Stiglund, Y.; Nordliner, S.;
  • Poster
    Konferenz "Uran-Bergbau und Hydrogeologie II", Freiberg, 15.-17. September 1998

Publ.-Id: 1114 - Permalink


Spatial Distribution of Defects in Ion-Implanted and Annealed Si: the RP/2 Effect
Kögler, R.; Yankov, R. A.; Kaschny, J. R.; Posselt, M.; Danilin, A. B.; Skorupa, W.;
  • Nuclear Instruments and Methods in Physics Research B 142 (1998) 493-502

Publ.-Id: 1113 - Permalink


Post Test Calculations to 11% Break LOCA Experiments at the Integral Test Facility ISB-VVER Using the Thermohydraulic Code ATHLET
Krepper, E.;
The considered test was a break on the upper plenum with different modes of emergency core cooling. The reference case was the non-availability of emergency cooling. Injecting the emergency coolant into the cold leg, no increasing of rod cladding temperatures was observed, but natural circulation instabilities occurred. Injecting the cooling into the hot leg, the cooling situation was getting worse. Due to the injected cold emergency coolant, the fluid density in the discharge volume was enhanced and the break mass flow increased. The observed events in the test were reproduced by the code with good agreement

  • Nuclear Engineering and Design 170 (1997) pp. 3-7

Publ.-Id: 1112 - Permalink


Post Test Calculations for a Small Break LOCA Experiment at the Integral Test Facility ISB-VVER Using the Thermalhydraulic Code ATHLET
Krepper, E.;
The ISB-VVER facility of the Elektrogorsk Research and Engineering Center is currently the only operating integral test facility for the thermal hydraulic behaviour of the Russian pressurized water reactor VVER-1000. In 1993 it was decided, to perform a test for a small break at the upper plenum with locked rotor of all circulating pumps as the 1st Russian Standard Problem. The experimental results were made available to the Research Center Rossendorf, where post test calculations were carried out using the GRS-code ATHLET. The main results of these calculations are presented in this paper.
  • Lecture (Conference)
    Jahrestagung Kerntechnik Mannheim 1996, Proceedings pp. 122-125
  • Contribution to proceedings
    Jahrestagung Kerntechnik Mannheim 1996, Proceedings pp. 122-125

Publ.-Id: 1111 - Permalink


Thermal Dilepton Signal Versus Dileptons from Open Charm and Bottom Decays in Heavy-Ion Collisions
Gallmeister, K.; Kämpfer, B.; Pavlenko, O. P.;
  • Open Access LogoForschungszentrum Rossendorf; FZR-209
  • Physical Review C, Vol. 57 (1998) pp. 3276-3283

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Publ.-Id: 1110 - Permalink


A Mixed-Ligand P,S,N-cis-Dioxorhenium(V) Complex by Ligand Exchange Reaction on trans-monooxo-trichloro-bis(triphenylphosphine)rhenium(V): Formation and Structural Studies
Friebe, M.; Jankowsky, R.; Spies, H.; Seichter, W.; Papadopoulos, M.; Chiotillis, E.; Johannsen, B.;
  • Polyhedron Vol. 17, No. 21, pp. 3711-3720, 1998

Publ.-Id: 1109 - Permalink


Damage in silicon carbide induced by Rutherford backscattering analysis
Fukarek, W.; Yankov, R. A.; Anwand, W.; Heera, V.;
  • Nuclear Instruments and Methods in Physics Research B135-138 (1998) 460

Publ.-Id: 1108 - Permalink


Dependence of the Silicon Detector Response to Heavy Ions on the Direction of Incidence: Computer Simulations Versus Experimental Data
Pilz, W.; von Borany, J.; Grötzschel, R.; Jiang, W.; Posselt, M.; Schmidt, B.;
  • Nuclear Instruments and Methods in Physics Research A 419 (1998) 137-145

Publ.-Id: 1107 - Permalink


A Parallel Code for Kinetic 3D Lattice MC Simulations of Nucleation, Growth and Ostwald Ripening of Nanocrystals
Schmeißer, N.; Kunicke, M.; Heinig, K.-H.;
The continuing exponential increase in computer power together with the recent developments of very efficient numerical procedures allow nowadays to perform predictive atomic-scale computer simulations for material science. This holds especially for advanced microelectronic devices where functional units consists more and more often of 10^6 atoms or even less. In this situation the design of new materials and devices is more and more frequently supported by atomic-scale computer simulations.

A kinetic 3D Monte-Carlo code based on stochastic probabilistic two-center cellular automaton using a double bookkeeping technique, one in the particle vector and the other in the lattice space was originally coded in PASCAL and tested on an INTEL PC, later in C and on HP workstations. This implementation should be speeded up considerably in order to undertake real scientific simulations. The only way to get the needed speedup is parallelisation.

We started with a look at the given sequential code, translated it into C and run it on our S-Class Server. While translating we had to understand a lot of things, e.g. the double booking technique, so that we could do first steps of scalar optimisation during this process.

The most simple idea of a parallel approach is distributing the lattice across the processors. But because of the physical problem modelling the growth of clusters of implanted particles in the lattice such an approach will lead to load imbalances and destroy the effect of parallelisation.

With an another approach we tried to distribute the work done in the particle space instead of the lattice space. We developed a graph-theoretical approach based on skeletons to find out a work distribution across 2^n processors that assure s a good load-balance. The disadvantage of this approach is the work needed to compute the distribution which is of order O(n^3) compared to the simulation which is of order O(n).

At this point it turned out the given model was not suitable for parallelising the algorithm. So we had feed-back with the physicist and together we developed a model of the physical process where the algorithm which solves the problem could be formulated in parallel. The new model allowed us to divide the solution into three main steps, where two of them can be done parallel and will therefor improve the speed of the algorithm.

We implemented this algorithm in a mixed language modularised program using FORTRAN for the computational part and C for the I/O part. The program runs on our S-Class server using maximum 8 processors.

In our presentation the methodology of creating an optimised parallel code for the Monte-Carlo simulation of Ostwald Ripening, the schema of the parallel code and first real physical simulation results will be shown.
  • Lecture (Conference)
    The 13th Annual HPC User Group Conference 1998

Publ.-Id: 1106 - Permalink


No Carrier Added Preparations of '3+1' Mixed-Ligand 99mTc Complexes
Seifert, S.; Pietzsch, H.-J.; Scheunemann, M.; Spies, H.; Syhre, R.; Johannsen, B.;
  • Appl. Radiat. Isot. Vol. 49, Nos 1-2, pp. 5-11, 1998

Publ.-Id: 1105 - Permalink


Differentiation Between Specific and Nonspecific Effects Related to P-Glycoprotein Inhibition in Immortalized Rat Brain Endothelial Cells
Bergmann, R.; Brust, P.; Johannsen, B.;
  • International Journal of Clinical Pharmacology and Therapeutics, Vol. 36, No. 1, 1998 (46-49)

Publ.-Id: 1104 - Permalink


Computer Simulation of Ion-Assisted Thin Film Deposition
Möller, W.;
  • Radiation Effects and Defects in Solids, Vol. 141, pp. 73-81

Publ.-Id: 1103 - Permalink


Computer Simulation of Precipitate Coarsening: A Unified Treatment of Diffusion and Reaction Controlled Ostwald Ripening
Strobel, M.; Reiss, S.; Heinig, K.-H.; Möller, W.;
In Ion Beam Synthesis (IBS) of nanoclusters the postimplantation
annealing step causes major redistribution of the implanted impurity atoms
by Ostwald ripening (OR). The diffusion-reaction equations describing OR
are highly nonlinear. Therefore, analytical studies are restricted to special
cases like the asymptotic behaviour, the diffusion or reaction controlled
limit, low cluster concentration, etc. An alternative to analytical studies
of OR is the numerical integration of the diffusion-reaction equations.
Using this method we take into account the diffusion and reaction control
of OR, i.e. we present for the first time an unified treatment for the
whole range of and in between the diffusion and reaction controlled limits.
Based on a local mean field theory, our model starts with a multipole expansion
of the concentration field, which satisfies the stationary diffusion equation.
Using appropriate boundary conditions on the precipitates we derive self-consistently
the governing equations for the evolution of the clusters. Alternatively
to Ewald's summation method we apply a Yukawa-like screening of precipitates.
The dependence of the particle radius distribution (PRD) the critical radius
and the density of nanoclusters on process parameters will be discussed.
  • Rad. Eff. Def. Sol. 142 (1997) 99

Publ.-Id: 1102 - Permalink


Comparison of YAP and BGO for high resolution PET detectors.
Kapusta, M.; Pawelke, J.; Moszynski, M.;
The goal of this work was to evaluate the potential of small YAP:Ce crystals, especially designed for a high-resolution PET system. We directly compared the scintillator properties of 3x3x20 mm3 crystals YAP with those of BGO. The light output, energy resolution, detection efficiency and timing properties for the irradiation using 137Cs and 22Na sources were investigated. Special consideration was given to the influence of the reflector coating on the light output as well as on the overall performance of the quality of the studied crystals.
  • Nuclear Instruments and Methods in Physics Research A 404 (1998) 413-417

Publ.-Id: 1101 - Permalink


Thermodynamics of the PHI4 Theory in Tadpole Approximation
Peshier, A.; Kämpfer, B.; Pavlenko, O. P.; Soff, G.;
Abstract
Relying on the Luttinger-Ward theorem we derive a thermodynamically selfconsistent and scale independent approximation of the thermodynamic potential for the scalar Φ4 theory in the tadpole approximation. The resulting thermodynamic potential as a function of the temperature is similar to the one of the recently proposed screened perturbation theory.
  • Open Access LogoForschungszentrum Rossendorf; FZR-208
  • Europhysics Letters 43 (4), pp. 381-385 (1998)

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Publ.-Id: 1099 - Permalink


Modifizierung der tribologischen, mechanischen und korrosiven Eigenschaften von Siliziumnitrid-Keramik mittels Ionenimplantation
Brenscheidt, F.;
  • Open Access LogoForschungszentrum Rossendorf; FZR-207, Dissertation; TU Dresden, Dez. 1997

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Publ.-Id: 1098 - Permalink


States of Seniority 3 and 5 in the N=48 Nucleus 87Y
Schwengner, R.; Reif, J.; Schnare, H.; Winter, G.; Servene, T.; Käubler, L.; Prade, H.; Wilhelm, M.; Fitzler, A.; Kasemann, S.; Radermacher, E.; von Brentano, P.;
  • Physical Review C Volume 57, Number 6, pp. 2892-2902

Publ.-Id: 1096 - Permalink


Stability versus Reactivity of "3+1" Mixed-Ligand Technetium-99m Complexes in Vitro and in Vivo
Syhre, R.; Seifert, S.; Spies, H.; Gupta, A.; Johannsen, B.;
  • Europ. Journal of Nuclear Medicine,Vol. 25, No. 7, July 1998, 793-796

Publ.-Id: 1095 - Permalink


Gasgehaltsmessung mit nadelförmigen Leitfähigkeitssonden in schäumenden Medien
Kern, T.;
  • Poster
    DECHEMA Jahrestagung 1998
  • Contribution to proceedings
    DECHEMA Jahrestagung 1998, Fachtreffen Sicherheitstechnik, Tagungsband II, S. 163-164, Wiesbaden, 26.-28. Mai 1998

Publ.-Id: 1094 - Permalink


Workshop "Meßtechnik für stationäre und transiente Mehrphasenströmungen" , 6.-7. November 1997 in Rossendorf
Prasser, H.-M.; (Editor)
  • Open Access LogoForschungszentrum Rossendorf; FZR-204, Dezember 1997 (Tagungsband)

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Publ.-Id: 1093 - Permalink


Institute of Bioinorganic and Radiopharmaceutical Chemistry; Annual Report 1997
Johannsen, B.; Seifert, S.;
  • Open Access LogoForschungszentrum Rossendorf; FZR-200

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Publ.-Id: 1092 - Permalink


Measurement and Simulation of the Turbulent Dispersion of a Radioactive Tracer in a Two-Phase Flow System
Hensel, F.; Rohde, U.;
Studies on the measurement of turbulent dispersion of a radiotracer in an experimental setup with natural convection liquid-gaseous flow were carried out at the Forschungszentrum Rossendorf. Liquid-gaseous bubbly flow was generated in a narrow tank by injection of pressurized air into water or by catalytic disintegration of H2O2. A small amount of a positron emitting radiotracer liquid ( 18F in an aqueous NaF solution) was injected instantaneously at a certain point of the tank. The Positron Emission Tomography (PET) technique was used to observe the spreading of the tracer liquid in the bubbly flow. A double head gamma detector array was used for measuring the positron annihilation rate which is proportional to the tracer concentration. The dispersion coefficient D for the tracer liquid was calculated from the experimental data assuming an isotropic spreading of the concentration profile after separation of the linear displacement of the maximum concentration point. Calculations of the two-phase flow with spreading tracer were carried out for selected experiments using the computational fluid dynamics code CFX-4. The Euler-Euler continuum approach including a homogeneous low Reynolds number K,? -model was applied for the two-phase flow. Turbulent Prandtl numbers for gas and tracer dispersion were varied. In case of higher gas injection rates into water (superficial gas velocities jgas of 5 - 15 mm/s), a reasonable agreement was achieved between calculated and measured values of the tracer transport velocity and the dispersion coefficient. A nearly linear correlation between jgas and D was found in agreement with other authors. However, it was necessary to take into account the significant deviation of the tracer distribution from the ideal diffusion equation solution in some cases, in particular if the tracer has been spread over upwards and downwards regions of the natural circulation velocity field. Further investigations are necessary to improve the agreement between measured and calculated values of the dispersion coefficient and tracer transport velocity in the case of H2O2 disintegration and low gas superficial velocities.
  • Contribution to external collection
    M. Rahman, C. A. Brebbia, G. Comini (Hrsg.) Advances in Fluid Mechanics II, Southampton 1998, ISBN 1-853-12589-X, p. 283
  • Lecture (Conference)
    Advances in Fluid Mechanics II (AFM98). Udine (Italy) May 13-15, 1998

Publ.-Id: 1091 - Permalink


Einfluß von Zusätzen niedermolekularer oberflächenaktiver Stoffe auf den Massenaustrag bei der Druckentlastung eines verdampfenden Stoffsystems
Lucas, D.; Prasser, H.-M.; Kern, T.;
Das Schaumverhalten eines Stoffsystems bei Druckentlastungsvorgängen hat einen wesentlichen Einfluß auf die Druckabfallgeschwindigkeit und die ausgetragene Masse. Es wurden kleinmaßstäbliche Druckentlastungsversuche mit einem 1,9 l Gefäß durchgeführt. Das Abblasen erfolgte über eine kopfseitige Abblaseleitung mit einer Blende. Unter sonst gleichen Bedingungen wurde reines Wasser und Wasser mit Zusatz von Isobutanol abgeblasen. Gemessen wurden der Behälterdruck, die ausgetragene Masse, sowie Temperaturen und Dampfgehalte an jeweils 2 verschiedenen Höhenpositionen. Es wurden Experimente mit einem Blendendurchmesser von 2 mm und 3 mm sowie Isobutanolzusätzen von 2, 4 und 6 Gew.% durchgeführt. Für beide Abblasequerschnitte zeigte sich eine deutliche Zunahme der ausgetragenen Masse mit der Isobutanolkonzentration. Auf Grund der Schaumbildung und des dadurch vergrößerten Flüssigkeitsaustrags wird der Druckabbau zu Beginn des Druckentlastungsvorgangs behindert. Löst sich schließlich die Oberkante der Schaumschicht vom Deckel, erfolgt der Druckabbau auf Grund der dann geringeren Masse im Behälter schneller.
  • Lecture (Conference)
    GVC-Fachausschuß-Sitzung "Mehrphasenströmungen", 2.-6. März 1998, Aachen

Publ.-Id: 1090 - Permalink


Einfluß der Abblaseleitung auf die Notentspannung von Reaktoren
Lucas, D.; Prasser, H.-M.;
Die Einrichtung zur Druckentlastung (Sicherheitsventil, Berstscheibe) ist in der Praxis über eine mehr oder weniger lange Abblaseleitung mit dem Reaktor verbunden. Bei der Auslegung der Sicherheitseinrichtung wird jedoch lediglich der notwendige Ausströmquerschnitt ermittelt. Berücksichtigt wird dabei gegebenenfalls der Druckverlust in der Leitung. Die Auswirkungen auf die Dynamik des Druckentlastungsvorgangs während des zweiphasigen Ausströmens bleiben bisher weitgehend unbeachtet. Aus diesem Grund wurden verschiedene Modelle für die Simulation des gekoppelten Systems bestehend aus Druckbehälter, Abblaseleitung und Entlastungsarmatur aufgestellt. Dabei wurden mehrere Varianten von vereinfachten Leitungsmodellen untersucht. Zur Überprüfung der Modellgüte wurden dabei Ergebnisse von Experimenten genutzt, die an der Druckhalterversuchsanlage DHVA der Hochschule für Technik, Wirtschaft und Sozialwesen Zittau/Görlitz durchgeführt wurden und bei denen Massenstrompulsationen bei Abblasen auftraten. Die Schwingungen hängen sehr empfindlich von einzelnen Parametern des Schaummodells, des Modells für die Kopplung zwischen Behälter und Abblaseleitung und des Modells für die Abblaseleitung ab. Experimentelle Daten zu diesen Schwingungen stellen daher eine ausgezeichnete Grundlage für die Validierung von Codes zur dynamischen Simulation eines Blow-Down Systems dar.
  • Poster
    DECHEMA-Jahrestagung '98, 26.-28. Mai 1998, Wiesbaden
  • Contribution to proceedings
    DECHEMA Jahrestagung '98, Tagungsband S. 158-159, Wiesbaden, 26. - 28.05.1998

Publ.-Id: 1089 - Permalink


BRICK - ein Simulationstool für Mehrphasenströmungen in Behältern auf der Basis einer Partikelmethode
Lucas, D.;
Im Rahmen der Entwicklung eines Gesamtmodells für die dynamische Simulation komplexer Druckentlastungssysteme bestehend aus Reaktor, Abblaseleitung,
Entlastungsarmatur und Auffangeinrichtungen wurde ein 1-D-Behältermodell
aufgestellt. Die Transportvorgänge im Behälter werden auf der Grundlage einer
neu entwickelten Partikelmethode gelöst. Dadurch wird numerische Diffusion
vermieden, was insbesondere bei der Berücksichtigung von Diskontinuitäten, wie
z.B. dem Gemischspiegel, von Vorteil ist. Die implizite Wiedergabe der aktuellen Position des Gemischspiegels sowie ein spezielles Interface ermöglichen die
Beachtung der Entwicklung einer Schaumkrone am Übergang zwischen dem
Zweiphasengemisch und dem Gasraum. Die weitgehende Entkopplung der einzelnen
Phänomene erlaubt eine modulare Codestruktur, bei der Modelle für
Einzelphänomene leicht ausgetauscht werden können.
  • Lecture (Conference)
    GVC-Jahrestagung '98, 30.9.-2.10.1998, Freiburg
  • Chemie-Ingenieur-Technik (70) 9198 pp. 1139

Publ.-Id: 1088 - Permalink


The Nuclear Structure of 126Te Studied with (d,p), (d,3He) and (d,d') Reactions*
Ott, J.; Doll, C.; von Egidy, T.; Georgii, R.; Grinberg, M.; Schauer, W.; Schwengner, R.; Wirth, H.-F.;
  • Nuclear Physics A 625 (1997) 598-620

Publ.-Id: 1087 - Permalink


Development of Segmented Ge Detectors for Future GAMMA-Ray Arrays
Eberth, J.; Thomas, H. G.; Weisshaar, D.; Becker, F.; Fiedler, B.; Skoda, S.; von Brentano, P.; Gund, C.; Palafox, L.; Reiter, P.; Schwalm, D.; Habs, D.; Servene, T.; Schwengner, R.; Schnare, H.; Schulze, W.; Prade, H.; Winter, G.; Jungclaus, A.; Lingk, C.; Teich, C.; Lieb, K. P.;
The EUROBALL Cluster detector is composed of seven encapsulated Ge detectors
in a common cryostat with a total volume of 2000 ccm of HP Germanium. The
development and the performance of the Cluster detector is summarized.
Up to six Cluster detectors were used in pre-EUROBALL experiments at the
S-DALINAC Darmstadt, at the tandem-postaccelerator facility of the MPI-K
Heidelberg and the UNILAC at GSI. Examples of these experiments - the excitation
of dipole modes with (gamma, gamma')-reactions and the first coincidence
spectroscopy of the N=Z nucleus 68Se with a CLUSTER Cube - are
discussed. The development of segmented encapsulated Ge detectors for a
MINIBALL at the radioactive beam facility REX-ISOLDE has been launched.
The status of the project is presented.
  • Progr. Part. Nucl. Phys., Vol. 38, pp. 29-37, 1997

Publ.-Id: 1084 - Permalink


Structure of Laser-Deposited Fe/Al-Multilayers
Noetzel, J.; Geisler, H.; Gorbunov, A.; Dietsch, R.; Mai, H.; Mensch, A.; Möller, W.; Pompe, W.; Reuther, H.; Tselev, A.; Wieser, E.; Worch, H.;
Fe/Al nm-period multilayers deposited by pulsed laser deposition were investigated by conversion electron Mößbauer spectroscopy and transmission electron microscopy. No Fe-Al intermetallic phases were found in the
intermixed transition range with an Al-concentration of 20-60 at.%. A qualitative depth distribution of the impurity concentration in the transition layers between subsequent Fe and Al layers is suggested.
  • Contribution to proceedings
    Proceedings of TATF 98 18.3.-20.3.1998 in Regensburg (6th International Conference on Trends and new Applications of thin Films)
  • Materials Science Forum, Vols. 287-288 (1998), pp. 455-458

Publ.-Id: 1083 - Permalink


Complex Formation between Uranyl and Arsenate Studied by Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS)
Rutsch, M.; Geipel, G.; Bernhard, G.; Nitsche, H.;
  • Lecture (Conference)
    Vortrag am 18.11.1997 im National Laborstory Livermore

Publ.-Id: 1081 - Permalink


Laser Induced Photoacoustic Spectroscopy with OPO/FDO Systems of the Complex Formation in the System UO22+ and CO32-
Geipel, G.; Brendler, V.; Bernhard, G.; Nitsche, H.;
  • Lecture (Conference)
    Vortrag am 17.11.1997 in LLNL

Publ.-Id: 1080 - Permalink


Laser Induced Spectroscopy at the Institute of Radiochemistry Rossendorf
Geipel, G.; Brendler, V.; Bernhard, G.; Nitsche, H.;
  • Lecture (Conference)
    LANL, Actinide and Environmental Structural Chemistry, Los Alamos, New Mexico, USA, 25.11.1997

Publ.-Id: 1079 - Permalink


Post Test Calculations of NOKO Bundle Experiments
Schaffrath, A.;
The safety concept of the new innovative boiling water reactor
SWR1000, which is developed by Siemens AG, is aiming at the
increase of safety margins and of the grace period for operator
actions during accidents by increasing the water inventory
inside the pressure vessel, by the arranging large water pools
in- (core flooding pool) and outside of the containment (dryer-
separator storage pool), simplifying the (emergency) cooling
systems and further decreasing the failure probabilities of
safety systems. Therefore, active safety systems are substituted
by passive ones or combined with passive safety systems in cases
where a replacement is not possible. The function of passive
systems is directly based on the physical phenomena: gravity,
natural convection and/or evaporation. Their effectiveness is in
dependent of operator actions. Therefore, smaller failure rates
are assigned to passive safety systems. The probability of
severe accidents of the new SWR is reduced significantly.

For the experimental investigation of the operation mode and the
effectiveness of these passive safety systems the multipurpose
thermohydraulic test facility NOKO was constructed at the
Forschungszentrum Jülich (FZJ) within a German collaboration
sponsored by the German Federal Ministry of Education, Sciences,
Research and Technology (BMBF) and German Utilities (EVU). The
facility has a maximum power of 4 MW for steam production and a
maximum operating pressure of 10 MPa.

In the EU BWR R&D Cluster six test series with an emergency
condenser test bundle and four test series with a single tube
were performed in 1996. Within the Physics and Thermalhydraulics
Complementary Actions to the BWR Cluster (BWR/CA) the Forschungs
zentrum Rossendorf (FZR) e.V. has performed 10 post test calcula
tions and an additional blind test calculation of NOKO bundle
experiments. The tests were selected by FZJ. The results of
these calculations are presented in this paper.

Post test calculations of NOKO experiments were performed with
an improved version of ATHLET. To calculate the heat transfer
coefficients during condensation in horizontal tubes the module
KONWAR has been developed and implemented in ATHLET. KONWAR is
based on the flow regime map of Tandon and includes several semi-
empirical correlations for the determination of the heat trans
fer coefficients. The post test calculations presented here
prove qualitatively and quantitatively the expected operation
mode and the capacity of the emergency condenser. Additionally
the blind calculation proves, that the improved version of
ATHLET (ATHLET with the extension KONWAR) is able to perform
proper calculations.
  • Lecture (Conference)
    TOPSAFE 98, Valencia 15.-17. April, Spanien, Beitrag TSC4-b
  • Contribution to external collection
    TOPSAFE 98, Valencia 15.-17. April, Spanien, Beitrag TSC4-b

Publ.-Id: 1078 - Permalink


Analytisches Modell zur Berechnung der Übertragungsfunkionen für das Neutronenflußrauschen in WWR-440 Reaktoren bei stochastischen Schwingungen der Regelelementunterteile
Meyer, K.; Hollstein, F.;
Control elements of VVER-440 type reactors consist of absorber and fuel parts. They can approximately be considered as spatial double pendulums. The length of both parts is equal to the height of the core. In the present paper the main interest is directed to the neutron noise due to random vibrations of the fuel parts (lower parts of the pendulums). It is assumed, that the fuel parts of all control elements are completely inserted into the core. A homogeneous cylindrical reactor model is used to describe the neutron flux. It is also assumed, that the control elements can be excited to flow induced random 3D transverse oscillations and pendulum motions. The transfer functions for the considered two kinds of control element motions were calculated by means of the Prompt-Response-Approximation for the Modified-One-Group-Diffusion-Equation. Using numerical results, studies have been made to clear up the contribution of the random pendulum motions to the neutron noise.
  • Open Access LogoForschungszentrum Rossendorf; FZR-205

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Publ.-Id: 1077 - Permalink


Die Randschichtausbreitung bei der Plasma-Immersions-Ionenimplantation
Mändl, S.;
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-206

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Publ.-Id: 1076 - Permalink


Microstructural Investigation of Ion Beam Synthesized Germanium Nanoclusters Embedded in SiO2 Layers
Markwitz, A.; Schmidt, B.; Matz, W.; Grötzschel, R.; Mücklich, A.;
  • Nuclear Instruments and Methods in Physics Research B 142 (1998) 338-348

Publ.-Id: 1075 - Permalink


Determination of U(VI) Reduction after Bacterial Metabolization by Uranium LIII-Edge Xanes Spectroscopy
Reich, T.; Panak, P.; Mack, B.; Baraniak, L.; Denecke, M. A.; Hennig, C.; Roßberg, A.; Selenska-Pobell, S.; Bernhard, G.; Nitsche, H.;
  • Other report
    HASYLAB Jahresbericht 1997

Publ.-Id: 1072 - Permalink


Uranium LIII XANES and EXAFS on the Uranyl Unit in a Single Crystal with Linear Polarized Synchrotron Radiation
Hennig, C.; Denecke, M. A.; Roßberg, A.; Zahn, G.; Reich, T.; Bernhard, G.; Nitsche, H.;
  • Other report
    HASYLAB Jahresbericht 1997, 823 (1998)

Publ.-Id: 1071 - Permalink


N.C.A.11C-Labelling of Benzenoid Compounds in Ring Positions: Synthesis of 3-Nitro-/ 3-11C/ Toluene and 4-Nitro-/ 4-11C/ Toluene and Their Corresponding Toluidines
Mäding, P.; Steinbach, J.;
  • Journal of Labelled Compounds and Radiopharmaceuticals XLI, 647-656 (1998)

Publ.-Id: 1070 - Permalink


Bestimmung der Neutronenflußdichten in den Bestrahlungseinrichtungen des BER II bei der HEU-LEU Umstellung
Stephan, I.; Gawlik, D.; Gatschke, W.;
  • Lecture (Conference)
    Jahrestagung Kerntechnik 1998, Tagungsbericht, Mannheim 1998, S. 631 ff.
  • Contribution to proceedings
    Jahrestagung Kerntechnik 1998, Tagungsbericht, Mannheim 1998, S. 631 ff.

Publ.-Id: 1069 - Permalink


Finite Element Based Vibration Analysis of WWER-440 Reactors
Altstadt, E.; Weiß, F.-P.;
A finite-element-model describing the mechanical vibrations of the whole
WWER-440 primary circuit was established to support the early detection of mechanical component faults. A special fluid-structure module was developed to consider the reaction forces of the fluid in the downcomer upon the moving core barrel and the rector pressure vessel. This fluid-structure interaction module is based on an approximated analytical 2D-solution of the coupled system of 3D fluid equations and the structural equations of motions. By means of the vibration model all eigenfrequencies up to 30 Hz and the corresponding mode shapes were calculated. It is shown that the fluid-structure interaction strongly influences those modes that lead to a relative displacement between reactor pressure vessel and core barrel. Moreover, by means of the model the shift of eigenfrequencies due to the degradation or to the failure of internal clamping and spring elements was investigated.Comparing the frequency spectra of the normal and the faulty structure, it could be proved that a
recognition of such degradations and failures even inside the reactor pressure vessel is possible by pure excore vibration measurements.
  • Lecture (Conference)
    ICONE‘98, International Conference on Nuclear Engineering, San Diego, May 10-15, 1998
  • Contribution to proceedings
    Proceedings of the 6th International Conference on Nuclear Engineering (ICONE-6) San Diego, May 10-15, 1998

Publ.-Id: 1066 - Permalink


Finite Element Based Stress Analysis of BWR Internals Exposed to Accident Loads
Altstadt, E.; Weiß, F.-P.; Werner, M.; Willschütz, H.-G.;
During a hypothetical accident the reactor pressure vessel internals of boiling water reactors can be exposed to considerable loads resulting from temperature gradients and pressure waves. The finite element (FE) analysis is an efficient tool to evaluate the consequences of those loads by computing the maximum mechanical stresses in the components. 3 dimensional FE models were developed for the core shroud, the upper and the lower core supporting structure, the steam separator pipes and the feed water distributor. The models of core shroud, upper core support structure and lower core support structure were coupled by means of the substructure technique. All FE models can be used for thermal and for structural mechanical analyses. As an example the FE analysis for the case of a station black-out scenario (loss of power supply for the main circulating pumps) with subsequent emergency core cooling is demonstrated. The transient temperature distributions within the core shroud and within the steam dryer pipes as well were calculated based on the fluid temperatures and the heat transfer coefficients provided by thermo-hydraulic codes. At the maximum temperature gradients in the core shroud, the mechanical stress distribution was computed in a static analysis with the actual temperature field being the load. It could be shown that the maximum resulting material stresses do not exceed the permissible thresholds fixed in the appropriate regulations. Another scenario which was investigated is the break of a feed water line leading to a non-symmetric subpressure wave within the reactor pressure vessel. The dynamic structural response of the core shroud was assessed in a tranisient analysis. Even for this load case the maximum resulting stresses remain within the allowed limits at any time.
  • Lecture (Conference)
    Jahrestagung Kerntechnik‘98, München, 26.-28. Mai 1998, Tagungsbericht S. 721-724
  • Contribution to proceedings
    Jahrestagung Kerntechnik‘98, München, 26.-28. Mai 1998, Tagungsbericht S. 721-724

Publ.-Id: 1065 - Permalink


Dynamic in situ Diagnostics Using High-Energy Ion Beam Analysis
Möller, W.;
  • Nuclear Instruments and Methods in Physics Research B136-138 (1998) 1203

Publ.-Id: 1064 - Permalink


Main Steam Line Break Analysis of a NPP with VVER by Means of the Coupled Code DYN3D/ATHLET
Kliem, S.; Grundmann, U.; Rohde, U.;
The coupling of advanced thermohydraulic codes with 3-dimensional neutron kinetic codes corresponds to the effort to replace conservative estimations by best estimate calculations. ATHLET is an advanced thermohydraulic code, developed by the German "Gesellschaft für Anlagen- und Reaktorsicherheit" (GRS). The DYN3D code, developed at Forschungszentrum Rossendorf (FZR) for the simulation of reactivity initiated accidents in nuclear reactors with hexagonal and Cartesian fuel element cross section geometry comprises 3-dimensional neutron kinetics, models for the thermohydraulics of the core and the thermomechanical fuel rod behaviour.

Both versions of DYN3D for hexagonal and Cartesian fuel element geometry were coupled with ATHLET according to two basically different strategies. The first way of coupling uses only the neutron kinetics part of DYN3D (internal coupling). In the second way, the whole core is cut out from the ATHLET plant model and is completely described by DYN3D (external coupling). In this case the values of pressure, mass flow rate, enthalpy and boron acid concentration at the bottom and at the top of the core have to be transferred between the codes. This way of coupling is efficiently supported by the General Control and Simulation Module (GCSM) of ATHLET.

The coupled code DYN3D/ATHLET was used to investigate the possibility of recriticality during an asymmetrical overcooling of the reactor core of a NPP with VVER-440 after a main steam line break (MSLB). This MSLB analysis was performed for hot zero power and end of fuel cycle conditions. Different coolant mixing conditions in the lower plenum of the reactor were simulated. The results show the importance of these conditions. In case of a realistic mixing model and without consideration of mixing, i.e. where each loop is connected to a particular 1/6 sector of the core, a recriticality after reactor scram was predicted. For ideal mixing only, recriticality can be avoided.

  • Contribution to proceedings
    Tagungsband Jahrestagung Kerntechnik '98, S. 15-19
  • Lecture (Conference)
    Jahrestagung Kerntechnik '98
  • Contribution to proceedings
    Proc. TOPSAFE `98, Session TSC-1a, ENS, Valencia (Spain), 1998
  • Lecture (Conference)
    TOPSAFE `98, Session TSC-1a, ENS, Valencia (Spain), 1998

Publ.-Id: 1063 - Permalink


Mechanical Response of a BWR to Loads Imposed by External Events
Altstadt, E.; Weiß, F.-P.; Werner, M.;
In the case of external events (e.g. earthquake or explosion pressure wave) the reactor pressure vessel (RPV) and its internal components are excited to mechanical vibrations. In such cases it is important to know the dynamic component stress for the assessment of the mechanical integrity of the system.
For this reason a theoretical global vibration model based on the finite element method (FEM) was developed for a German BWR. The model comprises the RPV including the main coolant pumps (MCP), the control element drives, the core flux measuring pipes and the RPV internals.
  • Lecture (Conference)
    Proceedings of IMORN-27, Valencia, Nov. 18-20, 1997
  • Contribution to external collection
    Proceedings of IMORN-27, Valencia, Nov. 18-20, 1997

Publ.-Id: 1062 - Permalink


Calculation of the NOKO Test B6-4
Schaffrath, A.; Dumaz, P.;
In 1997 a "BWR Physics and Thermohydraulic Complementary Action (BWR-CA)" was established to further assist and broaden the objectives of the "European BWR R&D Cluster for Innovative Passive Safety Systems". The activities are divided into 4 work packages (WP). The work presented in this paper is performed in WP2: Passive decay heat removal from the core region, where two different decay heat removal systems were investigated. These are isolation condensers (e.g. as operated in Gundremmingen A, Dodewaard or in the PANDA facility) or emergency condensers (e.g. as foreseen on the SWR1000 and tested in the NOKO facility).

Within the BWR Cluster the Forschungszentrum Jülich had performed 10 NO-KO tests. Six of these tests were carried out with a four tube bundle, four tests with a single tube. Several post test calculations of NOKO tests were performed in the BWR-CA by CEA with CATHARE V1.3U and FZR with an improved version of ATHLET Mod. 1.1 Cycle C. Additionally FZJ had specified data for a blind calculation. The blind NOKO calculation - as well as the other NOKO post test calculations - proves, that the modified version of CATHARE as well as the improved version of ATHLET (ATHLET coupled with KONWAR) are able to predict the global parameters in the range of the fluctuations of the measured values. In the next complementary action it is planned to perform additional post test calculations of the single tube experiments, experiments with gas/non-condensable mixtures and pretest calculations of a second optimized emergency condenser test bundle. The optimization suggest is to increase the heat transfer, which allows to decrease the number of heat exchanger tubes and the emergency condenser dimensions. This is desirable because it reduces the surface of the pressurized BWR circuit and the possibilities for leakages, which is a safety relevant task.
  • Contribution to proceedings
    Jahrestagung Kerntechnik '98 (1998), INFORUM GmbH, ISSN 0720-9207, S. 87-90
  • Lecture (Conference)
    Jahrestagung Kerntechnik '98 in München

Publ.-Id: 1061 - Permalink


Experimental and Analytical Investigations to Loss of Vacuum Accidents for Fusion Reactors
Krüssenberg, A.-K.; Moormann, R.; Hinssen, H.-K.; Hofmann, M.; Wu, C. H.;
Loss of vacuum accidents (LOVA) in fusion reactors will
lead to an air ingress into the vacuum vessel, oxidation
of the hot armour material and a partial mobilization of
the sorbed tritium. Also burnable carbon monoxide will
be formed during these accidents. In continuation to the
testing of carbon candidate materials for the First Wall
under oxidizing conditions in oxygen and steam in
collaboration with NET the carbon compound Aerolor AO5
of Carbone Lorraine has been examined in detail in the
experiments INDEX2 and SPALEX of the Institute of Safety
Research and Reactor Technology of Forschungszentrum
Jülich. The chosen parameters for these oxidation
experiments with oxygen in the inpore diffusion
controlled regime are temperatures between 973 K and
1173 K and partial pressures of oxygen between 1140 Pa
and 21000 Pa at system pressures between and; that means
reaction gas con centrations between 1 vol.-% and 20
vol.% oxygen in argon. From these results a semi-
empirical kinetic equation for the heterogeneous primary
reaction was developed. The equation considers the
dependence of the reaction rate on temperature, partial
pressure and burn-off of the material.
For calculations of LOVA the code RALOC Mod 4.0 AD -
developed by the Gesellschaft für Anlagen- und
Reaktorsicherheit (GRS) mbH has been extended by the
model COX (Carbon Oxidation) to consider carbon
oxidation kinetics. This kinetic model is based on the
above mentioned experimental results. First calculations
have been done for leak areas of 0.01 m², 0.1 m² and 1.0
m² and for different numbers of nodes in the reaction
chamber. The comparison of these results with earlier
calculations of JRC Ispra, GRS and Technicatome showed
that the new model COX and the nodalisation scheme lead
to more reliable statements concerning the spatial
dependencies especially for the burn-off of the armour
material and for the masses of the formed gases CO and
CO2.
  • Contribution to proceedings
    1998 ASME/JSME/SFEN ICONE-6, Proceedings of the 6th International Conference on Nuclear Engineering, May 10-14, 1998, San Diego, California, Beitrag 6515.
  • Lecture (Conference)
    6th International Conference on Nuclear Engineering, May 10-14, 1998, San Diego, California

Publ.-Id: 1060 - Permalink


Depth Profile Analysis: STEM-EDX versus RBS
Markwitz, A.; Matz, W.; Schmidt, B.; Grötzschel, R.;
  • Surface and Interface Analysis, Vol. 26, 359-366 (1998)

Publ.-Id: 1059 - Permalink


Anwendung der Entscheidungsanalyse bei der Sanierung von Altlasten
Kruber, S.;
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-201

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Publ.-Id: 1058 - Permalink


Berührungslose Detektion der Struktur und Messung ausgewählter Paramater von Zweiphasenströmungen durch Mustererkennungsverfahren unter Verwendung von Ultraschall als Meßsonde. Abschlußbericht zum Vorhaben 1500 967
Prasser, H.-M.; Schütz, P.; Kossok, N.;
Es wird ein Ultraschall-Meßverfahren für Zweiphasenströmungen vorgestellt, das die simultane Messung der Volumenstromdichte der Gas- und der Flüssigphase in einer Rohrleitung ermöglicht. Ein Prototyp wurde in Zusammenarbeit mit der Universität Nishny Novgorod (Rußland) aufgebaut. Es realisiert einen gepulsten Transmissions- und Reflexionsbetrieb mit Wellenleitersensoren, die auch an heiße Rohrleitungen bis zu 350°C direkt angekoppelt werden können. Kernstück der Meßmethode ist ein Mustererkennungsverfahren, das in bestimmten Volumenstrombereichen nach einer umfangreichen Kalibrierung (Trainingsprozeß) einen Meßfehler von kleiner 10 % besitzt, wenn die thermodynamischen und geometrischen Randbedingungen nahezu konstant bleiben. Durch die Erweiterung der Trainingsmatrizen um einen, die thermodynamischen Eigenschaften determinierenden Parameter (z. B. Temperatur, Druck) kann das Klassifizierungsverfahren auch auf Fälle mit veränderlichen Stoffwerten angewandt werden. Das Mustererkennungsverfahren und die Ultraschalltechnik wurden experimentell optimiert und erprobt. Die Ultraschallsignale wurden außerdem mit Hilfe der Methode des unüberwachten Lernens klassifiziert. Die gefundenen Gruppen von Signalmustern weisen eine deutliche Ähnlichkeit zu bekannten Strömungskarten auf. Es wird gezeigt, daß das Verfahren des unüberwachten Lernens sich für die objektive Aufstellung von Strömungskarten eignet. In einem speziellen Kapitel werden die Ergebnisse von Tests zur Füllstandsmessung in einem Segment der Hauptumwälzleitung von Druckwasserreaktoren vorgestellt.
  • Open Access LogoForschungszentrum Rossendorf; FZR-203 November 1997

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Publ.-Id: 1057 - Permalink


Polarization Observables in the Reaction NN -> NN O|
Titov, A. I.; Kämpfer, B.; Shklyar, V.;
Abstract:
We study the reaction NN → NNΦ slightly above the threshold within an extended one-boson exchange model which also accounts for uud knock-out. It is shown that olarization observables, like the beam-target asymmetry, are sensible quantities for identifying a ss admixture in the nucleon wave function on the few per cent level.
  • Open Access LogoForschungszentrum Rossendorf; FZR-202

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Publ.-Id: 1055 - Permalink


Bericht der Herbsttagung der Studiengruppe für Elektronische Instrumentierung vom 29. September bis 1. Oktober an der Universität in Frankfurt am Main
Gabriel, F.; Jainsch, R.;
  • Open Access LogoForschungszentrum Rossendorf; FZR-199

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Publ.-Id: 1054 - Permalink


X-Ray Diffraction Study of Phase Transitions in Sr0.75Ba0.25Nb2O6 between 20 and 400K
Prokert, F.; Ritter, H.; Ihringer, J.;
  • Ferroelectrics Letters, 1998, Vol. 24, pp. 1-7

Publ.-Id: 1053 - Permalink


Characterization of Vacancy-Type Defects in Ion Implanted and Annealed SiC by Positron Annihilation Spectroscopy
Anwand, W.; Brauer, G.; Coleman, P. G.; Skorupa, W.;
New examples of characterization of vacancy-type defects
in ion implanted and annealed SiC by the established technique of slow
positron implantation spectroscopy are presented. In particular, the estimation
of the depths of damaged regions and their change (a) after post-irradiation
annealing, or (b) due to variation of substrate temperature during implantation,
is addressed.
  • Lecture (Conference)
    Konferenz MRS Fall Meeting, Boston, MA, USA, Dec. 1 - 5, 1997

Publ.-Id: 1052 - Permalink


Sonderuntersuchungen zu Strömungsformen am NOKO Einzelrohr
Schaffrath, A.; Prasser, H.-M.; Böttger, A.; Jaegers, H.;
Im Rahmen des Forschungsvorhabens 15 NU 09485 "Berechnung des passiven Notkondensators eines mit Naturumlauf arbeitenden innovativen Siedewasserreaktors (SWR600) mit ATHLET" wurden vom Forschungszentrum Rossendorf e.V. Auswertungen und Interpretationen von Messungen zu Strömungsformen bei Kondensationsvorgängen in einem umfangreich instrumentierten Einzelrohr durchgeführt. Ziel der Experimente war, die Aussagesicherheit der NOKO-Bündelexperimente zu erhöhen sowie experimentelle Daten für die Validierung von Thermohydraulikprogrammsystemen (u.a. den ATHLET-Code) bereitzustellen.
Die theoretische Modellierung des Wärmeübergangs an der Innenseite der Notkondensatorrohre erfordert die Identifizierung der im aktuell betrachteten Rohrquerschnitt vorliegenden Strömungsform sowie die Auswahl einer geeigneten (d.h. strömungsformabhängigen) Korrelation zur Berechnung des Wärmeübergangskoeffizienten. Sensitivitätsanalysen haben gezeigt, daß sich im Betrieb der Notkondensatoren in Abhängigkeit von der Wirkung der Dampfschubspannung auf den Kondensatfilm sowie dessen Schwerkrafteinfluß zahlreiche Strömungsformen (z.B. eine Ring-, Schichten, Blasen-, Schwall- und Pfropfenströmung) einstellen. Da der Flüssigkeitsanteil längs des Kondensatorrohres zunimmt, können die verschiedenen Strömungsfor-men nacheinander auftreten bzw. ineinander übergehen.
  • Lecture (Conference)
    Jahrestagung Kerntechnik 98 (1998), INFORUM GmbH, ISSN 0720-9207, S. 83-86
  • Contribution to proceedings
    Jahrestagung Kerntechnik 98 (1998), INFORUM GmbH, ISSN 0720-9207, S. 83-86

Publ.-Id: 1051 - Permalink


Neue Rechnungen zu Lufteinbruchstörfällen bei Fusionsreaktoren mit einer Beschichtung des Reaktorraums aus CFC-Material
Krüssenberg, A.-K.; Hicken, E. F.;
  • Contribution to proceedings
    Jahrestagung Kerntechnik 1998 S. 573-576
  • Lecture (Conference)
    Jahrestagung Kerntechnik 1998, 26.-28.5.1998, München

Publ.-Id: 1050 - Permalink


Stickstofftransport während der plasmagestützten Randaufstickung nichtrostender Stähle - der Einfluß der passivierenden Oxidschicht
Parascandola, S.; Kruse, O.; Richter, E.; Möller, W.;
Plasmagestütztes Randaufsticken ist eine erfolgversprechende Technologie zur Verbesserung der Verschleiß- und der Korrosionseigenschaften von Bauteilen aus nichtrostendem Stahl. Bei moderaten Temperaturen (ca. 400°C) kann eine Randschicht mit einem hohem Gehalt an gelöstem Stickstoff (ca. 20at.%) erzeugt werden. Diese Randschicht weist eine deutlich erhöhte Härte und Verschleißbeständigkeit und eine hervorragende Korrosionsbeständigkeit auf. Die Prozesse, die zur Bildung dieser Randschicht führen, sind weitgehend unverstanden. Um den Einfluß der passivierenden Oxidschicht auf die Bildung der stickstoffreichen Randschicht zu untersuchen, ist ein in-situ Experiment mit einer gekreuzten Strahlgeometrie aufgebaut worden. Bei kontrollierten Restgaszusammensetzungen wird während des plasmagestützten Randaufstickens zeit- und tiefenaufgelöste Elementanalyse betrieben. Dabei wird zum Randaufsticken eine Hochstrom-Ionenquelle und zur tiefenaufgelöste Elementanalyse „elastic recoil detection analysis“ (ERDA) verwendet. ERDA ist sensitiv auf die leichten Elemente und wurde hier hinsichtlich schneller Datenaufnahme optimiert. Quantitative zeitaufgelöste Messungen der Elementverteilungen werden für verschiedene Sauerstoffpartialdrücke vorgestellt. Die Bildung der stickstoffreichen Randschicht ist stark mit der Reduzierung der Oxidschicht korreliert. Hohe Sauerstoffpartialdrücke stabilisieren die Oxidschicht. Dieses Ergebnis stimmt gut überein mit einem einfachen Transportmodell, das die Sauerstoffadsorptionsrate und die Zerstäubungsrate berücksichtigt.
  • Lecture (Conference)
    Nichtmetalle in Metallen: Tagung des Gemeinschaftsausschusses "Nichtmetalle in Metallen" der GDMB, 23-25 März 1998 in Münster / Nichtmetalle in Metallen '98: Vortragstexte einer Tagung des Gemeinschaftsausschusses "Nichtmetalle in Metallen" der G...
  • Contribution to proceedings
    Nichtmetalle in Metallen: Tagung des Gemeinschaftsausschusses "Nichtmetalle in Metallen" der GDMB, 23-25 März 1998 in Münster / Nichtmetalle in Metallen '98: Vortragstexte einer Tagung des Gemeinschaftsausschusses "Nichtmetalle in Metallen" der G...

Publ.-Id: 1049 - Permalink


Härtung von Edelstahl durch Stickstoff-Plasma-Immersions-Ionenimplantation
Richter, E.; Günzel, R.;
  • Ingenieur-Werkstoffe 6 (1997) 44

Publ.-Id: 1046 - Permalink


Noise Analysis Measurements and Numerical Evaluations of the Moderator Temperature Coefficient in PWRs
Laggiard, E.; Grundmann, U.; Rohde, U.; Weiß, F.-P.; Runkel, J.; Stegemann, D.;
The moderator temperature coefficient (MTC) of a 1400 MW pressurized water reactor (PWR) has been measured from neutron and temperature fluctuations in different reactor positions. In order to explain the deviations observed between the estimations, numerical evaluations of the MTC were performed using the 3D two energy groups DYN3D code for a prototype PWR. The differences between the experimental MTC estimations can be partially explained considering that the numerical MTC evaluations show a definite devitation of the neutronics from point kinetics.
  • Other report
    27th Informal Meeting on Reactor Noise (IMORN 27), Valencia, November 18 - 20, 1997
  • Lecture (Conference)
    27th Informal Meeting on Reactor Noise (IMORN 27), Valencia, November 18 - 20, 1997

Publ.-Id: 1045 - Permalink


Nicotinamide-Substituted Complexes as Redox Marker
Knieß, T.; Spies, H.; Brandau, W.; Johannsen, B.;
  • Journ. Labelled Comp. and Radiopharm. XLI, 605-614 (1998)

Publ.-Id: 1044 - Permalink


Annealing studies of chromium implanted silicon nitride ceramics
Brenscheidt, F.; Matz, W.; Wieser, E.; Möller, W.;
The effect of chromium implantation and subsequent annealing
on the hardness and wear behaviour of a silicon nitride-based ceramic is
investigated. Implantation energies were 200, 400, 1000 and 2000 keV, the
fluence was 1017 Cr+ ions cm-2 in all cases. The annealing temperatures
were 800 C, 1000 C and 1200 C. The phase composition was determined with
X-ray diffraction. Annealing at 800 C does not affect the crystal structure.
At 1000 C the -Si3N4-phase is formed for 1 and 2 MeV implantation energy.
At 1200 C, Cristobalite and Keiviite are formed at the lower implantation
energies; at higher energies -Si3N4 is formed. We discuss the phase formation
for the different implantation energies and annealing temperatures and
the relationship with the observed hardness and wear.
  • Nuclear Instruments and Methods in Physics Research B 127/128 (1997) 677-680

Publ.-Id: 1043 - Permalink


Surface Roughness with Nanometer-Scale Ag Particles Generated by Ion Implantation
Pham, M. T.; Matz, W.; Seifarth, H.;
Surfaces of SiO2, Si3N4, Ta2O5 and glass were implanted
with Ag+ ions. Studies using X-ray diffraction (XRD) and atomic force microscopy
(AFM) show that the surface morphology is dominated by metallic silver
features consisting of regularly shaped, mostly spherical, Ag particles
spanning a size range from some nanometers to some 100 nm in diameter.
The particle size metrics, distribution, shape, and their density are shown
to be controlled by the process paramters ion dose, dose rate, and ion
energy. Adjusting the energy of the incident ions results in various degrees
of submerging into the substrate including exposed Ag features anchored
onto the surface or buried Ag particles overcoated by a thin layer of the
matrix material. The substrate material differs by its ability of stabilizing
the dispersion and blocking the Ag movement. Ta2O5 and glass substrates
provide more homogeneously dispersed Ag particles, much smaller in size
and regularly shaped compared to SiO2 and Si3N4 substrate systems. Potential
application refers to surface enhanced Raman scattering.
  • Analytica Chimica Acta 350 (1997) 209-220

Publ.-Id: 1042 - Permalink


Comparison of Computer Generated and ERDA depth Profiles of Oxygen Implanted into Silicon with Plasma Immersion Ion Implantation
Barradas, N. P.; Maas, A. J. H.; Mändl, S.;
Plasma immersion ion implantation was used to implant
oxygen into silicon with nominal doses ranging from 2 x 1016 to 2 x 1017/cm2.
Positive Ions, O+2 and O+, with a continuous energy distribution between
0 and 40 keV were implanted. The plasma parameters and the geometrical
configuration of the implantation were chosen in order to follow closely
the assumptions of a theoretical model, which allowed to calculate the
energy distribution of the incident ions. Computer simulations were performed
to derive the resulting theoretical oxygen depth distribution. The agreement
found with the experimental depth profiles, measured by elastic recoil
detection analysis, is good. The small discrepancy observed is discussed
in terms of the shortcomings of the model used.
  • Nuclear Instruments and Methods in Physics Research B 124 (1997) 63-68

Publ.-Id: 1041 - Permalink


Quality assurance of heavy ion tumour therapy by means of positron emission tomography.
Enghardt, W.; Debus, J.; Hasch, B.-G.; Hinz, R.; Haberer, T.; Jäkel, O.; Lauckner, K.; Pawelke, J.;
no abstract
  • Poster
    IEEE Nuclear Science Symposium and Medical Imaging Conference, Albuquerque, New Mexico, 9-15 Nov, 1997
    Book of Abstracts(1997)102
  • Contribution to proceedings
    IEEE Nuclear Science Symposium and Medical Imaging Conference, Albuquerque, New Mexico, 9-15 Nov, 1997
    Book of Abstracts(1997)102

Publ.-Id: 1040 - Permalink


ULIII Polarized XAFS Studies on Ba[UO2PO4]2.8H2O
Hennig, C.; Denecke, M. A.; Roßberg, A.; Zahn, G.; Reich, T.; Nitsche, H.;
U LIII Polarized XAFS studies on Ba[UO2PO4]2·8H2O
C. Hennig 1, M. A. Denecke 1, A. Roßberg 1, G. Zahn 2,
T. Reich 1, H. Nitsche1
1 Forschungszentrum Rossendorf, Institut für Radiochemie,
PF 510119, D-01314 Dresden
2 Technical University of Dresden, Institute of Crystallography
and Solid State Physics, Zellescher Weg 16,
D-01062 Dresden

An experimental and theoretical study of the U LIII -edge polarization dependent XANES and EXAFS is presented for a single crystal of barium uranyl phosphate hydrate. Ba[UO2PO4]2·8H2O is built up by layers of [UO2]2+ and equatorial coordinated [PO4]3- tetrahedra. Layers are bridged by Ba2+, H+ and H3O+ cations giving an overall tetragonal (or nearly tetragonal) symmetry. The orientation of a crystal obtained by cleaving a larger crystal and used for the XAFS measurements was determined by x-ray diffraction. The layered structure of Ba[UO2PO4]2·8H2O exhibits preferred cleavage along {001} and parallel to {100}. Linear uranyl units are aligned parallel to [001]. {100} represents the least squares plane for the equatorial oxygen atoms. XAFS measurements were performed with the polarization vector aligned in the equatorial plane (parallel to [100] and [110]), as well as with the polarization vector oriented perpendicular to [010], with 90°, 60°, 45°, and 30° angles to [001].
Two different explanations of the resonance » 15 eV above the LIII -edge white-line maximum have been discussed. One explanation, based on pressure dependent measurements of UO3, attributed this feature to shake-up processes [1]. The other interpretation stems from ab initio multiple-scattering calculations using the FEFF program package. These calculations identify this feature as a multiple-scattering resonance associated with the axial U-O bonds in various uranium compounds [2], [3]. Our experimental investigations show that the relative intensity of this resonance increases if the polarization vector is aligned along the axial U-O bonds. This observation confirms the multiple-scattering assignment of this feature and is supported by our own theoretical FEFF calculations.
The U LIII -edge EXAFS show a strong polarization dependence, especially evident in the Fourier transforms at distances corresponding to uranyl axial oxygen atoms and equatorial atoms. This dependence strongly influences the effective coordination numbers, Ni, obtained in the data analysis.
The marked characteristics of such polarization-dependent XAFS spectra renders them useful as a unique indicator of uranyl orientation. For example, the specific binding sites and orientation of sorbed uranyl (actinyl) ions onto mineral surfaces can be determined with this method.

[1] Bertram, S., Kaindl, G., Jové, J., Pagès, M., Gal, J.: Phys.
Rev. B 52 (1989) 2680
[2] Hudson, E.A., Rehr, J.J., Buchner, J.J.: Phys. Rev. B 52
(1995) 13815
[3] Hudson, E.A., Allen, P.G., Terminello, L.J., Denecke, M.A.,
Reich, T.: Phys. Rev. B 54 (1996) 156
  • Contribution to proceedings
    Abstract für die Tagung der Deutschen Gesellschaft für Kristallographie 2.-5.3.1998 in Karlsruhe
  • Suppl. Z. Krist. 15, 156 (1998)
  • Poster
    Euroconference and NEA Workshop: Actinide-XAS-98, Grenoble, France, 04.-06.10.1998

Publ.-Id: 1039 - Permalink


Physically-based modeling of two-dimensional and three-dimensional implantation profiles: Influence of damage accumulation
Murthy, C. S.; Posselt, M.; Feudel, T.;
The alteration of the shape of one-dimensional, two-dimensional (2D), and three-dimensional (3D) range distributions with growing dose as well as the extension of amorphous zones formed at high doses is studied for 15 keV BF2+ and 30 keV P+ implantations into (100)Si using the dynamic binary collision code Crystal-TRIM. The range and damage profiles are calculated for the area 97.74 (parallel to [010]) × 97.74 (parallel to [001]) nm2 at the target surface irradiated by the ion beam and surrounded by impenetrable masks. The change of the shape of the 2D and 3D distributions in the lateral direction is less pronounced than in the depth direction. At low doses the lateral profile branches are determined by rechanneled particles, at high doses the enhanced dechanneling is the reason for the increased lateral straggling. The latter effect is responsible for the relatively large lateral extension of the amorphous zone beneath the masks. The simulated depth profiles of boron and phosphorus and the predicted thickness of the amorphous layer are in good agreement with experimental data.
  • Journal of Vacuum Science and Technology B 16 (1998) 440
  • Lecture (Conference)
    Proc. 4th Int. Workshop Measurement, Characterization and Modeling of Ultra-Shallow Doping Profiles in Semiconductors, Res. Triangle Park, USA, April 1997

Publ.-Id: 1037 - Permalink


Structure Investigation of the Influence of the Irradiation Temperature on the Formation of Defects in Nuclear Pressure Vessel Steel A 533-B-1
Große, M.; Nitzsche, P.; Böhmert, J.; Hempel, A.; Brauer, G.; Haggag, F. M.;
  • Contribution to proceedings
    Proceedings MRS 1996 Fall Meeting

Publ.-Id: 1036 - Permalink


Präparation und In-Vivo-Testung von Melanom-affinen '3+1' (99mTc)-Oxotechnetium(V)-Gemischt-Ligandkomplexen
Friebe, M.; Spies, H.; Johannsen, B.; Mohammed, A.; Eisenhut, M.;
  • Lecture (Conference)
    DGN-Tagung, 36. Internationale Jahrestagung, Leipzig, 01.-04. April 1998
  • Abstract in refereed journal
    Nuklearmedizin 37 (1998) A49

Publ.-Id: 1035 - Permalink


Rezeptoraffine Oxorhenium(V)-Komplexe als Inhibitoren der Monoaminoxidase im Rattenhirn
Matys, S.; Brust, P.; Scheunemann, M.; Pietzsch, H.-J.; Johannsen, B.;
In früheren Untersuchungen haben wir nachgewiesen, dass Oxorhenium(V)-Komplexe mit Ketanserin-, Cisaprid- und MDL72832-ähnlicher Struktur hohe Affinität zu Serotoninrezeptoren des Gehirns aufweisen, womit die analogen 99mTc-Verbindungen als potentielle Radiopharmaka von Interesse sind. Ihre Struktur ließ auch inhibitorische Wirkung auf die Serotonin abbauende Monoaminoxidase (MAO) vermuten. In Untersuchungen an Rattenhirnhomogenaten mit 1mM Tryptamin als Substrat beider Isoenzyme MAO A und MAO B, bzw. 1 mM Phenylethylamin als spezifisches Substrat für MAO B hemmt die Mehrheit der untersuchten Komplexe mit IC50 Werten zwischen 10-4 und 10-6 M das Enzym. Die höchste Affinität besitzt der abgebildete Komplex mit IC50=7*10-7±2 M.
Die räumliche Anordnung des protonierbaren Stickstoffs im Molekül ist dabei kritisch. Die Ergebnisse zeigen, daß bei der Bewertung von Radiotracern für das serotonerge System potentielle Wechselwirkungen mit der MAO berücksichtigt werden müssen.
  • Poster
    36. Intern. Jahrestagung DGN, Leipzig, 01.-04.04.1998
  • Abstract in refereed journal
    Nuklearmedizin 37 (1998) A51

Publ.-Id: 1034 - Permalink


Rheniumkomplexe von Steroidalen Estrogenen, Androgenen und Progestinen
Wüst, F.; Berger, R.; Katzenellenbogen, J. A.; Alberto, R.; Schubiger, P. A.; Spies, H.; Johannsen, B.;
  • Lecture (Conference)
    36. Intern. Jahrestagung der DGN, Leipzig, 01.-04. April, 1998
  • Abstract in refereed journal
    Nuklearmedizin 37 (1998) A45

Publ.-Id: 1033 - Permalink


Beeinflussung der99mTc-MIBI- und [18F]FDG-Aufnahme durch Inhibitoren des P-Glycoproteins
Bergmann, R.; Brust, P.; Johannsen, B.;
Das P-Glycoprotein (Pgp) ist ein energieabhängiges Efflux-Transportsystem für ein breites Pharmaka-Spektrum, welches in bestimmten Tumoren, aber auch in normalen Geweben, z.B. den Endothelzellen des Gehirns exprimiert wird. Die Pgp-Bewertung in Tumoren mit lipophilen Kationen (99mTc-MIBI, 99mTc-Tetrafosmin) wird durch verschiedene biochemische Veränderungen (z.B. des Energiestoffwechsels) erschwert. In Multitracerexperimenten an Hirnendothelzellen untersuchten wir die Veränderungen im Membranpotential (99mTc-MIBI, 99mTc-Tetrafosmin), des Glukoseumsatzes ([18F]FDG) und der Pgp-Aktivität ([3H]Vinblastin) unter dem Einfluß verschiedener Pgp-Inhibitoren (u.a. Verapamil, Vinblastin,Valinomycin). Die Zellaufnahme der Pgp-Substrate ([3H]Vinblastin, 99mTc-MIBI, 99mTc-Tetrafosmin) korrelliert unter Kontrollbedingungen mit dem Glucosemetabolismus ([18F]FDG). Bei Hemmung des Pgp zeigte sich allerdings in den meisten Fällen eine Verminderung der Akkumulation von FDG. Das Ionophor Valinonycin löst dagegen einen dramatischen Anstieg des Glucoseumsatzes aus, gleichzeitig ist die MIBI oder Tetrafosmin-Aufnahme verringert obwohl die [3H]Vinblasin-Akkumulation unverändert bleibt. Das zeigt, daß bei der Untersuchung von Pgp-Transportprozessen Sekundäreffekte auftreten können (hier Veränderungen des Energiestoffwechsels), die bei der Interpretation der Daten zu berücksichtigen sind.
  • Lecture (Conference)
    36. Intern. Jahrestagung DGN, Leipzig, 01.-04.04.1998
  • Abstract in refereed journal
    Nuklearmedizin 37 (1998) A17

Publ.-Id: 1032 - Permalink


Thermochromatography of Heavy Actinides - Adsorption of No-259 on Ti, V, Nb, Ta and Mo
Taut, S.; Hübener, S.; Eichler, B.; Türler, A.; Gäggeler, H. W.; Timokhin, S. N.; Zvara, I.;
  • Journal of Alloys and Compounds 271-273 (1998) 316-321
  • J. Less-Common Met. 271-273, 316 (1998)

Publ.-Id: 1030 - Permalink


Decay Study of Hot Nuclei below the Multifragmentation Threshold with the FOBOS Detector at Dubna
Herbach, C.-M.; Ortlepp, H.-G.; Wagner, W.;
Abstract
The first series of experiments at the FOBOS detector, using beams of the U-400M cyclotron of the Flerov Laboratory of Nuclear Reactions, was devoted to few-fragment decays of equilibrated systems. To exclude deep inelastic collisions or quasifission as sources of massive fragments, hot heavy nuclei were produced in the very asymmetric reactions 7Li (43 AMeV) + 232Th, 14N (34 AMeV) + 197Au, and 14N (53 AMeV) + 197Au, 232Th. Two- and three-fragment events were analysed on the base of masses and velocity vectors measured independently for each fragment. The events were sorted into excitation energy bins according to the linear momentum transfer following the massive transfer approach. Binary events were treated as fission. Fragment mass distributions as well as total kinetic energies were studied for an excitation energy range of 100 - 500 MeV. A new TKE parametrisation is proposed extending the Viola systematics to large mass asymmetries. With rising excitation energy the mass dispersion develops unexpectedly. Two new effects have been fourid and are discussed as consquences of the cooling down during the slow fission process at moderate E*, and of a strong decrease of the fission time at large E*. Ternary events were analysed by comparing measured velocity correlations with results of Coulomb trajectory simulations. If one fragment has intermediate mass (A = 10...30), two components in the relative velocities and the Z/A ratios confirm a sequential and a neck mechanism. For events with three fragments of comperable size neither the assumption of two sequential independent fission acts nor a nlultifragnlentaion-like scenario can reproduce the data. Agreement is achieved if these three-fragment decays are characterized by a collinear intermediate state followed by two scissions separated by no more than 280 fm/c, a very short time scale compared with usual saddle-to-scission intervals.
  • Open Access LogoForschungszentrum Rossendorf; FZR-198
  • Other report
    Konferenzbeitrag HIPH '97

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Publ.-Id: 1029 - Permalink


Metal Plasma Immersion Ion Implantation and Deposition (MPIIID): Chromium on Magnesium
Brückner, J.; Günzel, R.; Richter, E.; Möller, W.;
  • Poster
    Konferenz SMMIB 97, Gatlinburg, TE, USA, Sept. 1997
  • Surface and Coatings Technology 103-104 (1998) 227-230

Publ.-Id: 1028 - Permalink


Complexation of Uranium(VI) with the Main Components of Mine-Wood Degradation. Part 1. Complexation with Protocatehuic Acid, Vanillic Acid and Vanillin
Baraniak, L.; Schmidt, M.; Bernhard, G.; Nitsche, H.;

To consider the process of mine wood degradation and its concequences on the contaminant migration via aquatic path in risk assessments, e.g. for uranium mine restoration in the southern region of Saxony (Germany), the complexation of U(VI) with 3,4-dihydroxybenzoic acid (proto-catechuic acid), 4-hydroxy-3-methoxy-cinnamic acid (ferulic acid), 4-hydroxy-3-methoxybenzoic acid (vanillic acid) and 4-hydroxy-3-methoxybenzaldehyde (vanillin) was studied by potentiometric pH titration in carbonate-free solutions of 0.1 M NaClO4. These four complexants are reasonably stable monomeric intermediates in the microbial or hydrothermally driven spruce-wood lignin degradation and therefore play a role in natural water chemistry.

The evaluation of the pH titration curves was carried out with the classical theory of stepwise complex formation, analyzing Bjerrum’s formation function [1] and by non-linear fitting of the pH titration curve with Sayce’s multi-equilibria program "SCOGS" [2], considering hydrolysis and mixed-ligand complexation.

In the case of protocatechuic acid, a series of very stable (1:1) to (1:3) complexes are formed (log ß: 14.8/25.9/33.2). The constants calculated by Bjerrum’s formation function are in full agreement with the values of the SCOGS curve fitting, i.e. U(VI) hydrolysis is surpressed in the presence of this ligand. The complexes with ferulic acid and vanillic acid have a much lower stability: log ß11 values are to 6.88 and 7.16, respectively. In the case of ferulic acid, the assumption of the acidic species [UO2H(fer)]+ with log ß111 =11.9 improves the pH curve fit. Vanillin as complexant leads to pH curves that can be best fitted with the species [UO2(van)]+ and [UO2(van)2(OH)2]2- with log ß values of 4.47 and -3.95, respectively.

Using these data speciation calculations for some calcite-rich mine waters show that the strong U(VI)-carbonato complexes predominate. Under certain conditions only protocatechuic acid complexes can be formed.

  • Poster
    6th International Conference on Chemistry and Migration Behaviour of Actinides and Fission Products in the Geosphere: MIGRATION '97, Sendai, Japan, October 26-31, 1997

Publ.-Id: 1027 - Permalink


Characterization of the Redox Behaviour of Spruce-Wood Lignin and Humic Acid
Mack, B.; Abraham, A.; Baraniak, L.; Bernhard, G.; Nitsche, H.;

The redox behaviour of spruce lignin and humic acid was characterized by their redox potential and redox capacity. Such polyelectrolytes are formed in natural degradation processes including wood decomposition. They influence the redox situation in water of flooded uranium mines.

The first approach to the standard potential using a platinum electrode in combination with a silver-siver chloride electrode (3 M KCl) in a cell with liquid junction [1] was done in two ways: (1) by direct redox potential measurements [2] and (2) by redox titration with potassium hexacyanoferrate(III) [3], both in dependence on the pH. The redox potential of spruce lignin at pH 0 determined in that way was found to be 580±20 mV. That represents a rough E0 which can be arranged in the series of redox couples with decreasing E0. The reduction capacity determined from the titration at pH 9 amounts to 15±0.5 meq/g. Iron(III) in non-complexing solution (0.1 M KCl) was completely reduced by lignin with a maximum capacity of 6.5±0.8 meq/g in the pH range 2 to 2.5. Humic acids of different origin are characterized in the same way.

In addition, the iron(III) reduction by lignin and humic acid was examined in the pH range 3 to 5 by sqare-wave voltammetric analysis after a four weeks equilibration under inert gas at 25 °C. The iron(III) waves at -1.40 V and -1.60 V disappeared and the typical iron(II) signal was found at -1.33 V (all potentials were measured vs. Ag/AgCl, 3 M KCl). Changing the iron(III)-lignin ratio at pH 4.7±0.2 the maximum iron(III) quantity that can be reduced by a given lignin amount could be determined to 4.0 meq/g. At higher ratios the wave of the unreduced iron(III) was detected at -1.6 V (pH 4). At ratios below 4 meq/g iron(III) is quantitatively reduced and there is a linear relationship between the introduced iron(III) concentration and the intensity of the found iron(II) signal.

The analytical proof of the formed iron(II) was carried out by spectrophotometric determination with o-phenantroline. This sensitive method with a detection limit of 0.01 ppm iron(II) was adapted in such a way that iron(II) could be determined in the presence of iron(III).

  • Poster
    13th Radiochemical Conference, Marianske Lazne - Jachymov, Czech Republic, April 20.-24.04.1998

Publ.-Id: 1026 - Permalink


Simultaneous Measurement of 18F-FDOPA Metabolism and Cerebral Blood Flow in Newborn Piglets
Brust, P.; Bauer, R.; Walter, B.; Bergmann, R.; Füchtner, F.; Vorwieger, G.; Steinbach, J.; Johannsen, B.; Zwiener, U.;
  • Int. J. Devl. Neuroscience, Vol. 16, No. 5, pp 353-364, 1998

Publ.-Id: 1025 - Permalink


A Method for the Intrinsic Calibration of CsI(Tl) Detectors
Kamanin, D. V.; Wagner, W.; Ortlepp, H.-G.;
Abstract
A method for the intrinsic energy calibration of photomultiplier-coupled CsI(Tl) detectors is described. A simple empirical model of the scintillation light pulse-shape of CsI(Tl) crystals for light charged particles has been applied to simulate the particle identification matrix as it follows from the pulse-shape analysis method. The calibration procedure for the large-area CsI(Tl) detectors of the scintillator shell of the 4 π - array FOBOS for ions with Z < 4 at energies below 100 AMeV is based on the energies of the particle punch-through points.
  • Open Access LogoForschungszentrum Rossendorf; FZR-197
  • Nuclear Instruments and Methods in Physics Research A 413 (1998) 127-137

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Publ.-Id: 1023 - Permalink


RBS and Channeling Analysis of Cobalt Disilicide Layers Produced by Focused Ion Beam Implantation
Teichert, J.; Voelskow, M.; Bischoff, L.; Hausmann, S.;
Cobalt disilicide layers were formed by ion beam synthesis using 35 keV Co+ focused ion beam (FIB) implantation into silicon. A strong influence of the pixel dwell time on the layer formation was found. Only for short pixel dwell-times (about 1µs) closed layers with sufficient quality for device application could be formed. To understand the dwell-time effect the as-implanted samples were examined by Rutherford backscattering (RBS) and channeling analysis. A method is presented which allows quantitative measurements of samples where the implanted areas are smaller than the diameter of the RBS beam. Evidence has been obtained that the silicon crystal damage is less for short dwell-times.
  • Vacuum, Volume 51, Number 2, Pages 261-266, 1998
  • Lecture (Conference)
    10th Int. School on Vacuum, Electron and Ion Technologies, Varna, Bulgaria, Sept. 22 - 27, 1997

Publ.-Id: 1022 - Permalink


Elastic Proton-Deuteron Backward Scattering: Relativistic Effets and Polarization Observables
Kaptari, L. P.; Kämpfer, B.; Dorkin, S. M.; Semikh, S. S.;
Abstract
The elastic proton-deuteron backward reaction is analyzed within a covariant approach based on the Bethe-Salpeter equation with realistic meson-exchange interaction. Lorentz boost and other relativistic effects in the cross section and spin correlation observables, like tensor analyzing power and polarization transfer etc., are investigated in explicit form. Results of numerical calculations for a compbte set of polarization observables are presented.
  • Open Access LogoForschungszentrum Rossendorf; FZR-194
  • Physical Review C Vol. 57 (1998) 1097-1111

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Publ.-Id: 1021 - Permalink


Verification of the Code DYN3D/R with the Help of International Benchmarks
Grundmann, U.; Rohde, U.;
Different benchmarks for reactors with quadratic fuel assemblies were calculated with the code DYN3D/R. In this report comparisons with the results of the reference solutions are carried out. The results of DYN3D/R and the reference calculation for the eigenvalue keff and the power distribution are shown for the steady-state 3-dimensional IAEA-Benchmark. The results of NEACRP-Benchmarks on control rod ejections in a standard PWR were compared with the reference solutions published by the NEA Data Bank. For assessing the accuracy of DYN3D/R results in comparison to other codes the deviations to the reference solutions are considered. Detailed comparisons with the published reference solutions of the NEA-NSC Benchmarks on uncontrolled withdrawal of control rods are made. The influence of the axial nodalization is also investigated. All in all, a good agreement of the DYN3D/R results with the reference solutions can be seen for the considered benchmark problems.

  • Open Access LogoForschungszentrum Rossendorf; FZR-195 October 1997

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Publ.-Id: 1020 - Permalink


Entwicklung von theoretischen Schwingungsmodellen für WWER-Reaktoren auf der Grundlage der Finite-Elemente-Methode
Altstadt, E.; Weiß, F.-P.; Werner, M.; Bulavin, V.; Pavelko, V.; Gutsev, D.; Anikin, G.; Usanov, A.; Dodonov, V.;
In diesem Abschlußbericht wird ein Fördervorhaben beschrieben, welches auf die Unterstützung von 6 russischen Wissenschaftlern aus drei unterschiedlichen Institutionen abzielte. Ihre Arbeiten zur Anlagendiagnostik / Schadensfrüherkennung dienen der Erhöhung der Sicherheit von WWER-Reaktoren.
Das Vorhaben leistet einen Beitrag zur verbesserten Beurteilung der mechanischen Integrität von Reaktoren der russischen WWER-440 und WWER-1000 Baureihe, insbesondere zur empfindlichen Früherkennung und Lokalisation mechanischer Schädigungen an Reaktorkomponenten mit Hilfe schwingungsdiagnostischer Methoden. Zu diesem Zweck wurde das Finite-Element-Modell zur Simulation des mechanischen Schwingungsverhaltens aller Primärkreiskomponenten eines WWER-1000 erstellt. Dafür wurde das Programmpaket ANSYS® genutzt.
Das Berechnungsmodell zum WWER-440 wurde mit neueren Ergebnissen experimenteller Schwingungsuntersuchungen weiter justiert. Das Modell kann in der Hauptsache genutzt werden, um zu klären, wie sich unterstellte mechanische Defekte von Reaktoreinbauten auf die Schwingungen der Gesamtanlage auswirken. Diese Schadenssimulation ist besonders geeignet, empfindliche Meßpositionen für die on-line Überwachung zu finden und physikalisch fundierte Grenzwerte zu definieren.
  • Open Access LogoForschungszentrum Rossendorf; FZR-196 Oktober 1997

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Publ.-Id: 1019 - Permalink


Ellipsometric Investigation of Damage Distribution in Low Energy Boron Implantation of Silicon
Fukarek, W.; Möller, W.; Hatzopoulos, N.; Armour, D. G.; van den Berg, J. A.;
As the scaling of silicon devices to 100 nm channel length requires the formation of ultra-shallow (< 60 nm) junctions, high depth resolution analytical techniques become necessary for the characterization of the dopant and damage distributions. In situ single wavelength Ellipsometric
Etch Depth Profiling (EEDP) and non-destructive Variable Angle of incidence Spectroscopic Ellipsometry (VASE) have been used to obtain accurate and quantitative information on the depth profiles of radiation damage produced by low energy, room temperature ion implantation of B+ into Si.
  • Nuclear Instruments and Methods in Physics Research B 127/128 (1997) 879-883

Publ.-Id: 1018 - Permalink


Verhalten des Radiums im Flutungsprozeß des Uranbergwerks Königstein
Baraniak, L.; Thieme, M.; Funke, H.; Bernhard, G.; Nitsche, H.;
The interaction of radium with characteristic sediments of the upper Saxon Elbe river valley was investigated with the
aim to provide key data for transport modelling within the framework of mining site restoration. Adsorption
measurements therefore were carried out on site-specific sediments (different kinds of sandstone, claystone and lime
marl) using (1) acidic mine water coming from sulfuric acid residues of the former in-situ leaching process, (2)
groundwater that is inflowing into the mine and (3) mixtures of both which simulates certain stages of the mine flooding process. The distribution ratios were determined by batch experiments using an eight-week equilibration at aquifer temperature (14 °C). Radium adsorption from acidic mine water onto different kinds of sandstone is characterized by high distribution ratios (3400 mL/g). When contacted with groundwater, the sorption is decreased more than 20-fold (60-180 mL/g). For claystone and lime marl the distribution ratios amount to 130 and 480 mL/g, respectively, and they are nearly constant in the mine flooding process. The main adsorption mechanisms on the leached sandstone and the clayey sediments were identified as coprecipitation and ion exchange, respectively. The long-term migration behaviour in the aquifers of the south-east Saxon Elbe basin was calculated on the basis of Hadermanns' equation, considering retardation, dispersion and radioactive decay.
  • Wissenschaftliche Zeitschrift der TU-Dresden 46 (1997) Heft 6, S. 90-94

Publ.-Id: 1016 - Permalink


Interaction of Uranium(VI) with Arsenate in Aqueous Solution Studied by Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS)
Rutsch, M.; Geipel, G.; Bernhard, G.; Nitsche, H.;
  • Poster
    13th Radiochemical Conference, Marianske Lasne-Jachymov, Czech Republik, 20.-24.04.1998
  • Radiochimica Acta 86(1999), 135-141

Publ.-Id: 1014 - Permalink


Methods for Colloid Characterization in Environmental Waters Rich in Humic Substances
Zänker, H.; Richter, W.; Hüttig, G.; Schmeide, K.; Nitsche, H.;
  • Poster
    13th Radiochemical Conference, Marianske Lazne, 19-24.4.1998

Publ.-Id: 1013 - Permalink


Fine Structure of the E1 Response in 140Ce Below the Particle Threshold*
Herzberg, R.-D.; von Brentano, P.; Eberth, J.; Enders, J.; Fischer, R.; Huxel, N.; Klemme, T.; von Neumann-Cosel, P.; Nicolay, N.; Pietralla, N.; Ponomarev, V. Y.; Reif, J.; Richter, A.; Schlegel, C.; Schwengner, R.; Skoda, S.; Thomas, H. G.; Wiedenhöver, I.; Winter, G.; Zilges, A.;
The E1 response of the semi-magic nucleus 140Ce below the particle
threshold was measured in a (gamma, gamma') experiment utilizing the new
Euroball Cluster detector at the S-DALINAC. While the energy averaged data
are in good agreement with the tagged photon results, here they are resolved
for the first time into 54 individual transitions. A quasiparticle-phonon
model calculation including up to three-phonon configurations compares
well to the extracted strength distribution. The interference between one-
and two-phonon contributions is essential for a quantitative reproduction.
  • Physics Letters B 390 (1997) 49-54

Publ.-Id: 1011 - Permalink


Tilted Rotation of Weakly Deformed and Triaxial Nuclei
Frauendorf, S.;
  • Zeitschrift für Physik A 358, 163-167 (1997)

Publ.-Id: 1010 - Permalink


Dipole excitations in 122Te, 126Te and 130Te
Schwengner, R.; Schauer, W.; Winter, G.; von Brentano, P.; Eberth, J.; Enders, J.; von Egidy, T.; Grinberg, M.; Herzberg, R.-D.; Huxel, N.; Käubler, L.; von Neumann-Cosel, P.; Nicolay, N.; Ott, J.; Pietralla, N.; Prade, H.; Raman, S.; Reif, J.; Richter, A.; Schlegel, C.; Schnare, H.; Servene, T.; Skoda, S.; Stoyanov, C.; Thomas, H. G.; Wiedenhöver, I.; Zilges, A.;
Excited states of the nuclei 122Te, 126Te and 130Te
were populated via the (gamma,gamma') reaction at endpoint energies of
the bremsstrahlung between 4.5 and 5.5 MeV. Gamma rays were detected with
a EUROBALL-CLUSTER detector and a single detector. In all nuclei several
dipole transitions were identified at energies around 3 MeV. The lowest
corresponding J = 1 states are interpreted as two-phonon excitations. Quasiparticle-phonon-model
calculations predict one 1- state arising from the coupling
of the first quadrupole and the first octupole phonon and one 1+
state arising from the coupling of the first and the isovector second quadrupole
phonon at about 3 MeV. The calculated transition strengths are compatible
with experimental one.
  • Zeitschrift für Physik A 358, H.2, 197-198 (1997)

Publ.-Id: 1008 - Permalink


Particle-hole Induced Intruder Bands in117Sb and 119Sb
Lafosse, D. R.; Fossan, D. B.; Hughes, J. R.; Liang, Y.; Schnare, H.; Vaska, P.; Waring, M. P.; Zhang, J. Y.;
  • Physical Review C Volume 56, Number 2, 760-771

Publ.-Id: 1007 - Permalink


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