Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Noncovalent binding of pertechnetate may be of considerable interest as a new approach to labelling organic compounds with technetium without any reduction step, and for removal of pertechnetate as an environmental contaminant. Effective and selective complexation of pertechnetate should be realisable on the basis of molecular assembled supramolecular receptors that can provide multi-point fixation of tetrahedral anion pertechnetate as shown in the figure.

This paper reports on complexation experiments of pertechnetate and its nonradioactive congener perrhenate using different guanidinium compounds. The characterisation of these Tc(VII) and Re(VII) complexes are supported by X-ray crystal structures, TLC, infrared and NMR spectra. Liquid-liquid extraction studies are performed in order to monitor the influence of competition anions on phase transfer and to evaluate the stoichiometry of the complexes extracted. Lipophilicity and ionisation properties of guanidinium hosts and their Tc(VII)/Re(VII) complexes are determined by RP-HPLC. Molecular modeling calculations are used for the interpretation of the experimental results.

A new computer program has been developed for the control of the GSI Rotating Wheel Multi Detector Apparatus (ROMA) running under the Windows 95 and Windows NT 4.0 operating systems. It can be fitted to a lot of detection tasks in a highly flexible way.

The ROMA apparatus [1] has been used successfully for a lot of chemical investiga-tions of transactinide elements. In preparation of our seaborgium experiment at GSI in sum-mer 1998 [2] we developed a new control program. This was necessary because the old control code was running on an ATARI computer. In case of a damage of this computer, there would not have been the possibility of a replacement, which could possibly cancel the experiment.
The new program was designed to fulfill our special experimental requirements. A second feature is its support of the usual working conditions in a long running beam time. That means, persons without a deep understanding of a computer should be able to use this program without any difficulties, even if the programmer is not available. Thirdly, it should be highly flexible in order to adapt it to new experimental demands. Finally, the program should be to a great extent independent of the experiment hardware in order to be usable for similar apparatuses.
The program is written entire-ly in the C++ language using the Borland C++ Builder 1.0 programming environment based on the object oriented Virtual Component Library.

The program has to carry out the following tasks:

· control of the ROMA wheel movements according to the actual experiment;
· enabling and disabling the nuclear spectros-copy data acquisition;
· sending information about the actual ROMA status to the data acquisition hardware;
· processing requests of the acquisition hardware (e. g. switching in "daughter mode" [3]);
· processing user input (e. g. experiment and wheel setup dialog boxes).

The program is a Microsoft Windows applicatio ...

The paper presents high speed measurements of the transient void fraction distribution in the cavitating flow behind fast acting butterfly valves. A new electrode mesh sensor with a time resolution of 1024 frames per second was used. As a result, a new method to avoid cavitational water hammers was found.

A new wire-mesh sensor for gas-liquid flows is presented. Air-water mixtures in a vertical pipe were studied in a wide range of superficial ve-locities. Gas fraction and gas velocity profiles as well as a high resolution imaging of the flow structure are obtained. A volume flow rate measure-ment is feasible.

Needle Shaped Conductivity Probes have been applied to measure the properties of aqueous alcohol foams. Simultaneous usage of gamma densitometry and video imaging should allow a calibration and prove the values of the probe. The results show that the conductivity probes are able to measure in the foam zone as well as in the bubbly flow whereas the geometry of the foam causes some problems to detect reliably the foam bubbles.

The synthesis of n.c.a. [1-¹¹C]phenol (3) which is a further important aromatic ¹¹C unit for potential PET radiotracers is decribed for the first time. [1-¹¹C]aniline (1) was diazotized and the [1-¹¹C]benzenediazonium bromide (2) formed was concentrated in situ to give 3. Before diazotization, 1 had to be purified twice by means of an adsorber resin and a cation exchange resin. Starting from the purified 1, 3 was obtained in a radiochemical purity of about 79 % within 10 min. Related to crude 1 from the one-pot process, thereproducible radiochemical yield of 3 was about 16 % (decay-corrected). ¹³C/¹¹C Co-labelling experiments were carried out in order to confirm the identity of 3 and the position of the label.

The flow of electrically conducting fluids like sea water around bodies can be controlled by electromagnetic forces. These forces may be generated by a suitably chosen arrangement of permanent magnets and electrodes on the surface of the body.

We consider surface parallel Lorentz-forces acting in streamwise direction.This configuration allows to prevent the boundary layer from separation, resulting in higher lift and/or lower form drag of the body.Experimental results on the flow around a circular cylinder, an inclined plate and a hydrofoil are presented for Reynolds numbers up to 10**5. In the caseof the cylinder both steady and time-periodic forcing are applied.

The experiments were carried out in an open channel with sodium hydroxide as the working fluid and in a sea water facility. Flow visualizations showing serious separation delays will be presented together with values for drag and lift in different configurations.

Direct numerical simulations at low Reynolds numbers confirm the physical tendencies of the experiments.

Recently 3D neutron kinetics core models have been coupled to advanced thermohydraulics system codes. These coupled codes can be used for the analysis of the whole reactor system. In the framework of the international "Atomic Energy Research" (AER) association on VVER Reactor Physics and Reactor Safety, a benchmark for these code systems was defined. The reference reactor is the Russian VVER-440. The response of the reactor core to a main steam header break should be investigated. Solutions were received from the following five organizations: Kurchatov Institute Moscow (Russia), VTT Energy Espoo (Finland), Nuclear Research Institute Rez (Czech Republic), KFKI AEKI Budapest (Hungary) and Forschungszentrum Rossendorf (Germany). The paper presents an overview of the results of the benchmark. A good agreement in the thermohydraulic behaviour can be observed, the main differences between the solutions arise from the use of different nuclear data.

Extraction of pertechnetate with bicyclic guanidinium compounds has been studied in the system KTcO₄-buffer-H₂O/ligand-trichloromethane. Extraction data of guanidinium ligands have been compared with trialkylmethylammonium (Aliquat 336), tetraphenylphosphonium and tetraphenylarsonium chloride. The lipophilicity of extractants investigated was determined by RP-HPLC. The efficiency of pertechnetate extraction correlates with the lipophilicity of the guanidinium compounds. 1:1 complex formation in the organic phase was observed. The influence of hydroxide, chloride and bicarbonate on the pertechnetate extraction has been investigated. Pertechnetate is extracted with great preference over OH^-, Cl^- and HCO₃ ^-.

The tetraphenylphosphonium salt of tetra(1-methyl-1,2,3,4-tetrazole-5-thiolato)aurate(III) crystallizes as H2O solvate in the monoclinic space group C2/c with the gold atom situated on an inversion centre. The tetrazole rings are arranged almost orthogonally to the square coordination sphere. Au-S-C angles of 106.16(11) and 107.14(12)° have been found.

Für die Untersuchung von transienten Zweiphasenströmungen in Rohrleitungen, bzw. Rohrleitungssegmenten wurden im Fraunhofer-Institut für Umwelt, Sicherheits- und Energietechnik e.V. Oberhausen (UMSICHT) eine Druckstoßanlage als Freiluftanlage errichtet. Diese Anlage besteht aus zwei ca. 200 m langen Rohrleitungen mit den Nennweiten DN50 und DN100. Aufgabe des FZR war die Instrumentierung der Anlage mit Zweiphasenmeßtechnik sowie die Mitwirkung bei den experimentellen Untersuchungen und deren Interpretation. Die Anlage wurde vom FZR mit 16 nadelförmigen Leitfähigkeitssonden, einem neuartigen Gittersensor-Meßsystem und Ultraschall-Aufnehmern ausgerüstet. Mit den Gittersensoren, die 1024 Messungen pro Sekunde ermöglichten, wurde die bisher zugängliche Zeitauflösung hinsichtlich der Erfassung des gesamten Strömungsquerschnitts um etwa eine Größenordnung überboten. Die hinter einer schnellschließenden Klappe auftretenden großräumige Kavitationsblasen wurden visualisiert, deren maximale Ausdehnung in Strömungsrichtung mit zunehmender Strömungsgeschwindigkeit und Rohrleitungslänge anwächst. Innerhalb der Kavitationsblase liegt kurze Zeit nach dem Schließen der Armatur eine geschichtete Strömung vor. Die durch den Gegendruck abgebremste und erneut in Richtung auf die Armatur beschleunigte Flüssigkeitssäule prallt als Schwall auf die geschlossene Armatur, wodurch der Kavitationsschlag entsteht. Nachfolgend werden durch Reflexionen der Druckwelle weitere Kavitationsblasen erzeugt. In der Klappe tritt während des Schließvorgangs Kavitation auf. Die charakteristischen Dampfgehaltsverteilungen sind stark transient und weisen ausgeprägte räumliche Verteilungen auf. Auch vor der schnellschließenden Armatur treten unter bestimmten Bedingungen Kavitationsblasen auf, wenn die anfängliche Druckwelle vom Anfang der Rohrleitung als Entspannungswelle reflektiert wird und zurückkehrt.

The physico-chemical characterization of seaborgium as oxide hydroxide, performed in 1998 at the GSI accelerator UNILAC, continues earlier gas chromatographic studies of seabor-gium oxychlorides [1, 2]. In our former studies seaborgium behaved like a typical group 6 element despite the relativistic effects, which are increasing with the nuclear charge and cause unexpected chemical properties of the lighter transactinide elements rutherfordium and dubnium [3, 4]. To characterize seaborgium its properties have to be compared with those of other elements, first of all its homologues molybdenum and tungsten. The clear gra-dation of their chemical properties favors the oxides of the group 6 elements for studies of the influence of relativistic effects on the chemical properties of seaborgium. All the more as gas chromatographic studies of oxides or oxide hydroxides, respectively, provide high selec-tivity with regard to the lighter transactinides and interfering actinides. But on the other hand, the surface reactions dissociative adsorption and associative desorption governing the reac-tion ...

Mit dem bildgebenden Verfahren der Positronen-Emissions Tomographie (PET) können Transportprozesse, Enzymreaktionen und Rezeptoren in vivo, räumlich, zeitlich und quantitativ mit großer Sensitivität erfaßt werden. Entsprechend werden auch diagnostische Fragestellungen in der Medizin gelöst, die Veränderungen der genannten biochemischen Prozesse beinhalten. Eine Voraussetzung sind mit Positronenstrahlern z. B. mit ¹⁸F (T_1/2=110 min) oder ¹¹C (T_1/2=20 min) markierte Radiotracer, die hochspezifisch mit biologischen Bin-dungspartnern reagieren und eine geeignete Biokinetik besitzen. Zu solchen Radiotracern gehören auch ra-dioaktiv markierte Peptide und deren Derivate. In klinischen Untersuchungen werden bereits radioaktiv mar-kierte Somatostatinanaloga zur Tumordetektion eingesetzt (1). Ein ähnliches Potential besitzt auch Neuro-tensin (NT). Die G-Protein abhängigen Membranrezeptoren für NT werden auch in verschiedenen Tumoren, z. B. kleinzelligen Lungenkarzinomen, Pankreaskarzinomen u. a., überexprimiert (2). Ziel der Arbeiten ist es, einen Radiotracer zu entwickeln, der die in vivo Darstellung solcher Tumore mit PET ermöglicht. Dazu sind NT-Agonisten erforderlich, die durch Bindung und durch Internalisierung in der Targetregion angereichert werden, gleichzeitig aber auch schnell aus dem Blut eliminiert werden.
Die erstmalig mit 4-[¹⁸F]Fluorsuccinimidylbenzoat an der alpha-Aminogruppe des N-Terminus ¹⁸F-markierten lysinfreien Peptide 4-[¹⁸F]FB-NT(8-13) und 4-[¹⁸F]FB-[Arg⁸Y(CH₂NH)Arg⁹]NT(8-13) (4) wurden in vitro auf Rezeptoraffinität, Bindung an NT-Rezeptoren in Hirnschnitten und in vivo mit PET und durch Messung der Verteilung in Ratten charakterisiert.
Zur Affinitätsbestimmung in vitro wurden die radioaktiv markierten Peptide eine Stunde bei 37°C mit den stabil NTR1-Rezeptor exprimierenden HT-29 Zellen inkubiert. Beide Peptide binden an diesen Rezeptor. Für 4-[¹⁸F]FB-NT(8-13) wurde ein K_D von 5,1 nM ermittelt. In Simultanuntersuchungen mit [³H]NT korreliert deren Rez ...

The Rossendorf PET Center has a special feature: its PET cyclotron and the radiochemical laboratories are 500 metres away from each other. The distance is bridged by our radionuclide transport system (RATS).
Details of RATS such as layout, technical parameters, control system, radiation protection and our experience in long-distance transport of radionuclides, are indicated below.

Abstract. The title compound is formed from the five-coordinate [ReN(Et2dtc)2] upon reaction with B(C6F5)3. As a consequence of the formation of a nitrido bridge between Re and B the structural trans influence of the nitrido ligand decreases and its trans position which is not occupied in the edduct becomes available for co-ordination. The dimer is built up by two [Re{NB(C6F5)3}(Et2dtc)2] units which are linked by weak bonds between the metal and each one sulphur atom of the neighbouring unit (Re-S: 2.856(6) and 2.835(6) Å, respectively).
Keywords: Rhenium complexes, Nitrido bridges, Crystal structure, Dimerization

Abstract
A review on the synthesis and properties of the organometallic aqua-ion [M(OH2)3(CO)3]+ (M = Re, 99Tc, 99mTc), as relevant for radiopharmaceutical application, is presented. These important starting compounds can be prepared quantitatively a) on the no carrier added level (99mTc) in water or b) in organic solvents (Re, 99Tc) at atmospheric pressure in a short time and from [MO4]-. The main characteristics of these carbonyl complexes are the high substitution stability of the three CO ligands and the substitution lability of the coordinated water molecules. [M(OH2)3(CO)3]+ can be considered as a "semi aquo-ion". On the macroscopic level, upon titration with OH-, hydroxo-bridged oligomers have been isolated and characterized. The formation of hydroxo-bridged complexes is a consequence of the considerable Broenstedt acidity of [M(OH2)3(CO)3]+, whereas on the no carrier added level (n.c.a.) no such behavior was observed. Conditions and products of the water exchange by imidazole (im) and derivatives thereof (histamine, histidine) will be presented. The different mononuclear complexes with these ligands are of extraordinary inertness, which is the base for a potential application in biology and nuclear medicine. Finally, as a base for bioorganometallic chemistry, the adoption of the results from basic coordination chemistry to the labeling of biomolecules with an organometallic moiety will be exemplified with a selected penta-peptide and a recombinant single chain fragment.
Keywords: Tc-carbonyls, Tc-peptide complexes, scFv, cancer diagnosis, radiopharmacy

Synthesis, Characterization and Structure of Carbonyl and Hydrido Isocyanato Complexes of Ruthenium

Abstract. [Ru(CO)H(NCO)(PPh2Me)3] is formed during the reaction between [RuCl3(PPh2Me)3] and NaOCN in EtOH. The compound crystallizes in the monoclinic space group P21/n (a=1256.4(4), b=1487.2(2), c=1993.5(5) pm, b=97.28(1)°, Z=4). The distorted octahedral coordination sphere of RuII contains the phosphine ligands in meridional arrangement, their P atoms forming a plane together with the hydride ligand.
The reaction of [RuCl3(PPh3)2] with NaOCN in EtOH yields [Ru(NCO)-(CO)(CH3COO)-(PPh3)2] with trans coordinated Ph3P ligands.
The formation of hydrido, carbonyl and acetato ligands are due to the reaction of the transition metal with the solvent ethanol.

CoSi2 layers were produced by 70 keV Co focused ion implantation into (111)Si. Within a comparative study the CoSi2 layer quality and implantation damage were investigated as a function of pixel dwell-time and substrate temperature. Irradiation damage measurements were done by micro-Raman analysis. The results suggest that the dwell-time dependence of the CoSi2 layer formation - continuous layers for short and disrupted for long dwell-time - is caused by an adequate change from crystalline to amorphous silicon.

Using the spectral function F'(z)/F(z) the RPA correlation energy and other properties of a finite system can be written as a contour integral in a compact way. This yields a transparent expression and reduces drastically the numerical efforts for obtaining reliable values. The method applied to pairing vibrations in rotating nuclei as an illustrative example.

Der Rothschönberger Stolln leitet den Hauptteil der Grubenwässer des stillgelegten Freiberger Bergbaureviers in die Triebisch, einem Nebenfluß der Elbe. Das Ziel unserer Untersuchungen waren Aussagen über den kolloidalen bzw. kolloidgebundenen Anteil der wichtigsten toxischen Elemente am Mundloch des Stollens.

Es wurden Wasserproben in den Monaten Februar, April, August, Oktober sowie Dezember 1998 genommen. Nach Vor-Ort-Analysen (T, pH, O2-Gehalt, Redox-Potential und Leitfähigkeit) wurden die Proben im Labor kolloidchemisch mit den folgenden Techniken untersucht: Filtration bzw. Ultrafiltration, Zentrifugation, Sedimentation, Photonenkorrelationsspektroskopie (PCS) und Rastereletronenmikroskopie (REM) mit energiedisperser Röntgenanalyse (EDX). Die chemischen Analysen erfolgten mittels induktiv gekoppelter Plasma-Massenspektroskopie (ICP-MS), Atomabsorptionsspektroskopie (AAS) sowie Ionenchromatographie (IC). Von der Arbeitsgruppe J. Thieme (Universität Göttingen, Einrichtung Röntgenphysik) wurden parallel röntgenmikroskopische Untersuchungen mittels Synchrotronstrahlung durchgeführt.

Die PCS-Messungen an den Wasserproben ergaben, daß im Wasser des Rothschönberger Stollns Kolloidpartikel im Bereich von 100 bis 300 nm mit einem Maximum bei ca. 200 nm anwesend sind. Ihre Konzentration beträgt etwa 1 mg/l. Auf REM-Aufnahmen an beladenen Kernspurfiltern sind diese Partikel zu erkennen. Die Abnahme der Streulichtintensität bei den PCS-Messungen und der chemischen Gehalte in den Zentrifugaten nach der Parallel-Zentrifugation mit zunehmender Zentrifugalbeschleunigung ergeben, daß es zwei Gruppen von chemischen Elementen gibt. Während die Elemente Fe, Al, Pb, As, La, Y und Cu mit wachsender Zentrifugalbeschleunigung und beim Filtrieren mit sinkender Porenweite zunehmend abgeschieden werden, lassen sich alle übrigen der 25 mit ICP-MS/AAS analysierten Elemente nicht abzentrifugieren bzw. passieren alle Filter und Ultrafilter bis zu einer Porenweite von 3kD (ca. 1, ...

Im Rahmen des Verbundprojektes wurden theoretische Untersuchungen zur Modellierung der aus periodischen Anordnungen von alternierenden Magneten und Elektroden entstehenden wandnahen Lorentzkräfte bei Körperumströmungen in schwach-leitfähigen Fluiden durchgeführt. Hierbei konnte die Beschreibung der Lorentzkräfte für die klassische Konfiguration aus rechteckigen Magneten und Elektroden entschieden verbessert werden. Diese Modellierung war notwendige Voraussetzung für die Durchführung numerischer Simulationen von Platten- und Tragflügelumströmungen, für welche im Rahmen des Verbundprojektes Umströmungsexperimente an der HSVA durchgeführt wurden. Existierende Codes zur Berechnung turbulenter Umströmungen enthalten stets aus der Turbulenztheorie abgeleitete Wandfunktionen für den wandnahen Bereich. Diese können hier nicht verwendet werden, da die elektromagnetische Kraft gerade im wandnahen Bereich ihre Wirkung entfaltet. Deshalb wurde bewußt eine direkte numerische Simulation der Umströmung gewählt, obwohl diese zunächst auf relativ niedrige Reynolds-Zahlen beschränkt ist. Hierbei fand ein moderner Code mit spektralen Elementen Anwendung. Die Simulationen belegen, daß mit Hilfe der Grenzschichtkontrolle durch wandparallele Lorentzkräfte die Strömungsablösung an der Saugseite eines angestellten Ruders wirksam verzögert bzw. unterdrückt werden kann und damit eine erhebliche Auftriebsverbesserung erreicht wird.

Im Rahmen des Verbundprojektes wurden Meßreihen zur Umströmung einer ebenen Platte und eines ruderförmigen Körpers durchgeführt. Die jeweils oberflächenparallele elektromagnetische Kraft entsteht durch die Kopplung äußerer elektrischer und magnetischer Felder, die von einer streifenartigen, wechselweisen Belegung der Körperoberflächen mit Permanentmagneten und Elektroden ausgehen. Aufgrund der Feldverteilungen ist die Kraftwirkung auf den Bereich der Strömungsgrenzschicht beschränkt. Es fanden Permanentmagnete mit einer Feldstärke im Bereich von 0.2 bis 0.4 Tesla Verwendung. Die Elektroden wurden mit Gleichstrom gespeist, bei maximalen mittleren Stromdichten von bis zu 0.5 A/cm2. Die Plattenexperimente zeigten eine deutliche Reduzierung des Strömungswiderstandes, die bei maximalem Elektrodenstrom bis zu 80% betrug. Dieses Ergebnis wird allerdings durch einen energetischen Aufwand erreicht, der die Einsparungen beim Reibungswiderstand überwiegt. Laser-Doppler Messungen der Grenzschichtprofile bestätigten das physikalische Konzept, durch die elektromagnetische Volumenkraft der Grenzschicht ein stabileres Profil aufzuprägen, welches bei höherem Elektrodenstrom in das eines Wandstrahles übergeht. Die Untersuchungen am Ruder waren vor allem auf die Unterdrückung der Strömungsablösung an der Saugseite des Profiles und die damit verbundene Auftriebserhöhung gerichtet. Dadurch konnte eine deutlich verbesserte Ruderwirkung erreicht werden. Experimentelle Weiterführungen des Konzeptes und Probleme infolge der auftretenden Elektrolyseblasen sowie Aspekte der Auswahl geeigneten Elektroden-materials werden diskutiert.

Das Ablösen von Wirbeln an umströmten Körpern bzw. das Verständnis der körpernahen Strömungsgrenzschicht sind ein altes Problem der Strömungsforschung von offensichtlich großer praktischer Bedeutung. Der hochgradig nichtlineare Charakter dieser Phänomene beschränkt heute und auf absehbare Zeit die Möglichkeit einer direkten numerischen Simulation auf relativ niedrige, für praktische Zwecke wenig relevante Reynolds-Zahlen.
Für den Fall, dass die strömende Flüssigkeit eine elektrische Leitfähigkeit wie die von Seewasser hat, wird im Verbundprojekt die Idee einer gezielten Grenzschichtkontrolle mittels geeigneter elektromagnetischer Felder untersucht. Durch wechselweise Anordnung von Permanentmagneten und Elektroden kann, entsprechende Stromzufuhr an den Elektroden voraussgesetzt, eine Volumenkraft erzeugt werden, die die Strömungsgrenzschicht vollständig kontrolliert. Experimentelle Ergebnisse von Umströmungsmessungen an einer ebenen Platte und einem Ruder, durchgeführt an der Hamburgischen Schiffbauversuchsanstalt, zeigen eindeutig die starke elektromagnetische Kontrollmöglichkeit, die sich u. a. in einem erheblich reduzierten Strömungswiderstand oder einer Unterdrückung der Wirbelablösung niederschlägt. Die ernergetische Bilanz wird analysiert. Das Anwendungspotential im Schiffbau dieser relativ universell einsetzbaren Möglichkeit zur Strömungskontrolle wird aufgezeigt. Weiterführende, bisher nicht realisierte Varianten wie die Optimierung der Stromzufuhr oder der geometrischen Anordnung von Magneten und Elektroden werden diskutiert.

The present paper deals with a shape of a sharp phase boundary under conductivity controlled quasisteady solidification in a long cylinder with a given surface temperature and growth velocity. An approximate analytical closed form solution is obtained linearizing the Stefan problem in a neighbourhood of the practically desirable planar interface. The relative error of the solution is evaluated numerically and shown below 15% for reasonable interface depths (1/2 of the crystal radius) and desreasing linearly (or more rapidly) as interface deformation decreases.

Stability of a solid sphere in both uniform and linear alternating magnetic fields is considered with respect to virtual rotations. When the frequency of the alternating magnetic field exceeds certain critical threshold despending on the configuration of the field, the sphere is found to spin up around a horizontal axis. The physical mechanism of this instability is the same as that of operation of a single-phase electromotor. Sufficiently small rotational disturbances can be completely suppressed by imposing an axial steady magnetic field of strength comparable to hat of the alternating field. Non-linear stability analysis shows that for sufficiently high frequencies spin-up can be caused by large disturbances even when all infinitesimal disturbances are stable.

This paper presents a linear-stability analysis of small-amplitude oscillations of a solid body suspended in an alternating magnetic field. An original theory is developed for an arbitrary configuration of the magnetic field. Stability of a solid sphere in an axisymmetric linear magnetic field is calculated analytically. Oscillations of the sphere are found to develop as the frequency of the field exceeds certain critical threshold relative to the characteristic diffusion time of the magnetic field in the sphere. The critical frequency for the onset of oscillations in linear magnetic field coincides with the critical frequency for the spin-up instability in uniform magnetic field. The growth rate of oscillations attains a maximum at some frequency above the threshold and tends to zero at high frequencies.

The flow around bodies (cylinder, plate) can be controlled by applying
electromagnetic forces originating from electrodes and permanent magnets
suitably placed on the surface of the body. There is a large variety for
applying those forces with respect to the geometrical arrangement and the
electrical current feeding the electrodes. The goals of this approach are
flow stabilization, drag reduction or manoeuvrability of the body in an
electrically low-conducting fluid like seawater.

Experimental and numerical results of our research programme will be
presented. Experiments were performed using a copper sulfate electrolytic
solution, a sodium hydroxide loop and large saltwater channels available at
a shipbuilding research center in Hamburg. A strong flow control has been
confirmed. The energetic limitations of the approach will be discussed

The synthesis and in vitro autoradiography of a novel Tc-99m ligand with subnanomolar affinity to the 5-HT_2A receptor is reported. The complex combines the 4-(4-fluoro)-benzoyl piperidine portion derived from the 5-HT_2A receptor antagonist ketanserin with a neutral oxotechnetium(V) chelate in form of a mixed ligand "3+1" unit containing the SNS/S donor set. The analogous rhenium compound has been synthesized as a surrogate for the Tc-99m complex for use in receptor binding assays and for complete structural characterization.
In competition experiments the Tc-99 complex as well as its Re analogue display subnanomolar affinity towards the 5-HT_2A receptor (K_i 0.44 nM for Tc, 0.25 nM for Re).
The subnanomolar 5-HT_2A receptor binding of the Re complex was confirmed by functional in vitro antagonism of contractile effects evoked by 5-HT in rat arterial tissue. Re 1 inhibited 5-HT-induced, 5-HT_2A receptor-mediated contractions of isolated rat tail artery in a competitive fashion and possessed nanomolar affinity (pA₂ = 9.08). Like ketanserin, Re 1 displayed moderate affinity for adrenergic alpha_1D (pA₂ = 8.23) and histamine H₁ receptors (pA₂ = 8.00), and was >600fold up to 10,700fold less active at several neurotransmitter receptor subtypes.
Autoradiographic studies clearly indicate the accumulation of the Tc-99m compound in 5-HT_2A receptor rich areas of the brain. This enrichment can be blocked by 5-HT_2A receptor antagonists such as mianserin and ketanserin and is therefore specific.

A novel technique has been developed to measure the local velocities in opaque liquid flows such as liquid metals. The measuring principle is based on the separation of a direct mechanical interaction between flow and sensor tip and the optical acquisition and processing of the signal. In principle, this fact allows the extension of the range of applicability to higher temperatures. Furthermore, the insensitivity of the system to electrical noise and external magnetic fields can be considered as an
important advantage. Until now, the sensor has been tested in metallic melts up to temperatures of about 350 °C. We present measurements of the local velocity obtained in an eutectic InGaSn melt driven by a rotating magnetic field.

The nodal expansion method HEXNEM presented here bases on the transverse integration in axial direction and over the hexagonal plane of the nodes. For that, the 3-dimensional problem is split into a 2-dimensional problem in the hexagonal plane and a 1-dimensional problem in the z-direction. The 2-dimensional hexagonal problem is solved by an expansion of the neutron flux using two-dimensional polynomials and exponential functions being the solutions of the homogeneous equation. The transversal leakage term and the fission and scattering sources are approximated by the polynomials. To improve the accuracy, the method is not only based on the side averaged fluxes and currents but also on the corner point values. An analogous flux expansion is used for the solution of the 1-dimensional equation in axial direction. An inner and outer iteration procedure is applied to the solution of the problem. This method leads to an improvement of the accuracy against the simpler method implemented in the code DYN3D. It is shown by comparing the results with reference solutions of 2- and 3-dimensional benchmark problems.

During a hypothetical break of a BWR feed water line, the feed water distributor (FWD) inside the RPV is subjected to a high pressure load for a short time (10 ms). Because of the sudden coolant release from the inner volume of the FWD there is a pressure difference between the inner and outer surface. It is conservatively assumed that the pressure difference nearly can reach the operating pressure for a few milliseconds. The distributor box and the ring line of the feed water distributor are modelled with shell and volume elements capable of being used for large strain analyses with elastic-plastic material behaviour. It is demonstrated by non-linear static calculations (without consideration of the inertia of the material) that a buckling instability occurs at about 60% and 80% of the maximum pressure load. The arc-length method is used for the numerical solution to overcome these points of instability. To evaluate the influence of the dynamics of the process a non-linear transient analysis is done showing that the maximum strain occurs with a time delay to the pressure peak. The maximum plastic strain differs only insignificantly between static and transient solution. Inspite of the large strains the mechanical integrity is maintained during the hypothetical event.

The master curve concept allows to determine limit curves of fracture toughness for defined failure probabilities and a reference temperatures based on it. Thus fracture mechanical values can be supplied for the stress analysis. This paper presents the application of the master curve concept for the determination of the reference temperature over the thickness of a plate of RPV steel. It was shown that the master curve concept is applicable for the fracture mechanical characterisation of material in different conditions using small test specimens. A special problem with the use small specimens is the definition of the test temperature, at which fracture toughness values can be determined within the validity limits. It became clear that the criteria for definition the test temperature and the minimum number of specimens indicated in the ASTM E1921-97 standard are applicable and sufficient respectively only for homogeneous materials.

The problem of velocity reconstruction in conducting fluids from measurements of induced magnetic fields and electric potentials is discussed in spherical geometry.
Under the special case that the externally applied magnetic field is uniform and homogeneous throughout the fluid, the non-uniqueness problem is treated in detail. Assuming kinetic energy minimization for the moving fluid it is shown that the velocity field can be reconstructed completely.

In der vorliegenden Arbeit wird der Einsatz von Positronenemittern zur Bestimmung der Dichte eines zweiphasigen Mediums beschrieben. Zur Messung wird die Dichteabhängigkeit der Positronenreichweite ausgenutzt. Die Realisierbarkeit des Verfahrens wird zunächst in einer Computersimulation geprüft. Danach werden Experimente an einem hochauflösenden PET-Scanner vorgestellt. Bei diesen Experimenten wird die Dichteabhängigkeit der Reichweite von Positronen anhand von Modellmedien aus festen Schaumstoffen untersucht. Dabei werden die in der Computersimulation erzielten Ergebnisse bestätigt. Aus den experimentellen Ergebnissen wird ein Modell zur Beschreibung der Abnahme der Koinzidenzrate in Abhängigkeit von der Entfernung des Detektors von der Positronenquelle und der Mediendichte entwikkelt. Auf der Basis des Modells erfolgt die Konzipierung einer für die Dichtemessung optimierten Detektoranordnung. Die Funktionsweise dieses Detektorsystems wird in Form technischer Unterlagen und experimenteller Ergebnisse beschrieben. Mit dem optimierten Detektorsystem werden die Untersuchungen an den Modellmedien nochmals durchgeführt, wobei die bisherigen Ergebnisse bestätigt werden.

Das beschriebene Meßverfahren dient der Bestimmung der mittleren Dichte in einem überwiegend gasförmigen Medium, wobei eine Mittelwertbildung über das Meßvolumen erfolgt. Das Verfahren kombiniert die Vorteile bekannter densitometrischer Meßmethoden auf der Basis einer Schwächung von Strahlung, indem die hohe Dichtesensitivität der Positronenstrahlung mit der relativ geringen Absorption der energiereichen Annihilationsquanten kombiniert wird.

Uranium can occur in reducing phosphate-containing environments as uranium(IV)-hadrogenphosphate, U(HPO4)2.4H2O. No thermodynamic complex formation constants are available for the uranium(IV)-phosphate complexes because of their low water solubility. For example, the solubility product /1/ of U(HPO4)2.4H2O limits the uranium(IV) concentration in 1 M perchloric acid to less than 1.2 x 10-4 M. We studied the formation of this complex at uranium concentrations between 2x10-6 M and 1x10-4M by Laser-Induced Photoacoustic Spectroscopy in acid media. To determine the complex formation constant we measured and analyzed the spectra from 610 nm to 690 nm. The spectra were corrected for the absorption of the solvent water. The solvated uranium(IV) shows a very intensive absorption band with a maximum at 649.8 nm and a smaller maximum at 671.9 nm. We found a shoulder at 630.0 nm by deconvoluting the absorption spectrum. The spectrum changes with increasing phosphate concentration. At a total phosphate concentration of 1.5x10-3M, we found maxima at 656.6 nm and 667.0 nm. Additionally a shoulder at 645.0 nm is found. Two isosbestic points were determined at 661.4 nm and 669.4 nm. Results will be presented for the determination of the formation equilibrium and the complex formation constant(s).

A large variety of bacteria was demonstrated to be present in soil and sediment samples of a uranium waste pile in Saxony, Germany. Anaerobic sulfate-reducing bacteria belonging to the genus Desulfovibrio were found among them. The study of these bacteria, which are also known to reduce U(VI), is of great importance for the development of bioremediation procedures for decontamination of the environments polluted with uranium. The indigenous for the waste Desulfovibrio isolates were classified by the use of Amplified Ribosomal DNA Restriction Endonucleases Analysis (ARDREA), Random Amplified Polymorphic DNA (RAPD), Repetitive Primer Amplified Polymorphic DNA (rep-APD), 16S rDNA Sequencing, and as well as with classical microbiological methods.
Using 16S- and IGS-ARDREA the pile isolates were phylogenetically affiliated to Desulfovibrio vulgaris (oxamicus). The RAPD and rep-APD analyses have demonstrated a close genomic relationship between the pile isolates, but D. vulgaris (oxamicus) 1925T was not closely related to them. These results are in agreement to the taxonomic characterization of the strains by comparison of the fatty acid spectra.

In natural bioleaching systems autochtonic microorganisms are involved in the solubilization of metals from solid minerals. The widest spreaded mesophilic group of bioleaching microorganisms are the chemolithoautotrophic bacteria Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans.
From the soil samples of different sites and depths of a former uranium mine in Saxony, Germany, several Thiobacillus strains were cultured. They were classified by the use of the amplified ribosomal DNA restriction enzyme analysis (ARDREA). The genomic organization of the strains was investigated using random amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE).
All strains were affiliated to the species T. ferrooxidans. Moreover, it was possible to distinguish members belonging to the two closely related phylogenetic groups of the species - one related to the reference strain T. ferrooxidans ATCC 33020 (recovered from a uranium mine) and a second one, related to the strain 21834 (recovered from a coal mine).
By the use of the RAPD and PFGE fingerprinting methods it was demonstrated that the strains recovered from different depths differ in their genomic organization.

Bacterial diversity in subsurface soil samples drawn from different depths of several uranium waste piles was studied using the 16S rDNA retrieval. Extremely high diversity was found in all samples investigated. In particular, the presence of several dominant 16S rDNA groups related to the genara $\I Thiobacillus, Bacillus, Pseudomonas, Desulfovibrio $$END was demonstrated. One of these 16S rDNA groups was affiliated to the species $\IT. ferrooxidans$$END. Interestingly, this group includes three 16S rDNA types which possess slightly different sequences. Strains of $\IT. ferrooxidans$$END corresponding to two of the mentioned three 16S rDNA types were recovered from two soil samples polluted in different extend with heavy metals. The two groups of isolates have different genomic organization. In addition, the members of the group recovered from the more polluted sample are tollerant to higher concentrations of uranyl ions which are lethal for the isolates of the second group. The expression of at least three genes of the U-tolerant strains is influenced by by the presence of uranyl ions in the nutrient medium. The capability of the U-mine isolates to interact with U(VI) was studied, and it was found that they accumulate significantly higher amounts of U(VI) in comparison to several reference $\IT. ferrooxidans$$END strains recovered from other environments. Using time-resolved laser fluorescence spectroscopy it was shown that the complexes build by one of the U-waste isolates with U(VI) are much stronger than those build by the reference strains. This is the first report which demonstrates a microdiversity in closely related natural isolates of $\IT. ferrooxidans$$END. We suggest that the microdiversity obsrved reflects the genetic adaptation of the strains studied to the different heavy metal concentrations in their natural environments.

A large variety of bacteria was demonstrated to be present in soil and sediment samples of a uranium waste pile in Saxony, Germany. Anaerobic sulfate-reducing bacteria belonging to the genus Desulfovibrio were found among them. The study of these bacteria, which are also known to reduce U(VI), is of great importance for the development of bioremediation procedures for decontamination of the environments polluted with uranium. The indigenous for the waste Desulfovibrio isolates were classified by the use of Amplified Ribosomal DNA Restriction Endonucleases Analysis (ARDREA), Random Amplified Polymorphic DNA (RAPD), Repetitive Primer Amplified Polymorphic DNA (rep-APD), and 16S rDNA Sequence.
The 16S and IGS rDNA retrieval allowed us to affiliate the natural Desulfovibrio isolates to the subspecies Desulfovibrio vulgaris (oxamicus). Using RAPD and rep-APD analyses, the natural isolates were grouped in particular cluster which was not very closely related to the type strain D. vulgaris (oxamicus) 1925T. Results demonstrating the capability of the uranium waste isolates to reduce U(VI) to U(IV) will be presented.

Bacterial diversity in soil samples drawn from different depths of several uranium waste piles was studied using 16S rDNA retrieval, RISA and rep-APD. Extremely high diversity was found in all samples investigated. Several dominant 16S rDNA groups related to the genera Thiobacillus, Bacillus, Pseudomonas, and Desulfovibrio were demonstrated. One of these groups was affiliated to the species T. ferrooxidans. This group includes three 16S rDNA types with slightly different sequences. Strains of T. ferrooxidans corresponding to two of the mentioned three 16S rDNA types were recovered from two samples of the waste polluted in different extend with heavy metals. The interactions of the natural T. ferrooxidans strains with U(VI) were group-specific. Microdiversity at the level of 16S- and IGS-rDNA was found also among the group of the uranium reducing Desulfovibrio waste isolates. The latter were affiliated to Desulfovibrio vulgaris subspecies oxamicus. These natural isolates are able to reduce more effectively higher amounts of U(VI) than the reference Desulfovibrio strains. In contrast to the reference strains, the waste isolates reduce U(VI) to U(IV) independently of the pH range of the medium. This is the first report demonstrating microdiversity of closely related natural isolates of T. ferrooxidans and D. vulgaris subsp. oxamicus. We suggest that the microdiversity observed reflects the genetic adaptation of the strains studied to the different heavy metal concentrations in their natural environments.

In the natural bioleaching systems autochtonic microorganisms are involved in the solubilization of metals from solid minerals. The widest spreaded mesophilic group of bioleaching microorganisms are the chemolithoautotrophic bacteria Thiobacillus ferrooxidans, Thiobacillus thiooxidans, and Leptospirillum ferrooxidans.
From soil samples drawn from two particular sites of a former uranium mine in Saxony, Germany, which were polluted in different extend with heavy metals, several Thiobacillus strains were cultured. Using ARDREA the strains were classified in two uranium-waste-site-specific 16S rDNA subgroups of the species Thiobacillus ferrooxidans. Moreover, RAPD and PFGE analyses have demonstrated that the natural T. ferrooxidans isolates possess also group-specific genomic organization. The strains from the more polluted sample were tolerant to higher concentrations of uranyl ions which were lethal for the isolates of the second group. In these strains the expression of at least three genes was influenced by the presence of uranyl ions. The uranium binding capability of the uranium mine isolates was strain-specific and higher than those of the reference T. ferrooxidans strains recovered from other environments.

About 160 uranium minerals are known. Although many of these minerals show fluorescence properties, detailed fluorescence spectra are not published in the literature. We studied the fluorescence properties of 120 uranium minerals in order to provide a data base of potential solids that may form in the flooding process of defunct uranium mines.

Humic acids influence the speciation and migration behavior of actinide ions in the environment. Due to their complex and heterogeneous nature, a thermodynamically based description of their complexation behavior with metal ions is difficult. Numerous uncertainties exist in the description of the complexation process, e.g., the kind and number of complexing functional groups is uncertain.
We are investigating the influence of different functional groups on the complexation behavior of humic acids to improve the understanding of the humic acid - metal ion interaction. Such information is very important for a more precise modeling of geochemical processes in the presence of humic acids.
We synthesized and characterized synthetic and natural humic acids with blocked phenolic hydroxyl groups. With these humic acids, we investigate the influence of phenolic hydroxyl groups on the complexation behavior of humic acids with UO22+ ions. The investigations were carried out by laser-induced fluorescence spectroscopy and FTIR spectroscopy.
For the first time, we compared the complexation behavior of a modified and non-modified synthetic humic acid with UO22+ ions at pH 4 by laser-induced fluorescence spectroscopy. The spectroscopic results show that the blocking of the phenolic hydroxyl groups changes the interaction behavior between the humic acid and the UO2 2+ ion.

Organic materials, such as humic and fulvic acids, that are present in natural aquifers interact with dissolved inorganic contaminants and affect their sorption behavior on geological materials and thus, their migration in aquifers. Consequently, a quantification of the influence of humic material on radionuclide sorption is necessary.
Phyllite was used as site-specific rock material because it is quite common in the Western ‘Erzgebirge' in Saxony, Germany, and is closely associated with uranium deposits of the uranium mining areas in East Germany. Site specific humic acid, isolated from the bog ‘Kleiner Kranichsee' and a 14C-labelled synthetic humic acid were used for the experiments.
The effect of humic acid was studied on the sorption behavior of uranium(VI) onto phyllite and its mineralogical components muscovite, albite and quartz in air-equilibrated batch experiments as a function of pH. The uranium sorption is strongly affected by both the pH and the presence of organic material. The kinetics and reversibility of the uranium and humic acid sorption were studied using the 14C-labelled humic acid. Furthermore, the influence of competing sulfate ions on the uranyl and humic acid sorption onto phyllite was determined, because seepage waters of the uranium mining areas in Saxony contain, among other anions, relatively high concentrations of sulfate (3 10-2 M).

Beim Schließen einer schnellwirkenden Absperrarmatur in einer Rohrleitung, in der eine Flüssigkeit strömt, kann es zu Kavitationsschlägen kommen. In vielen technischen Anwendungen ist ein möglichst rasches Absperren von Rohrleitungen erforderlich, insbesondere wenn es um die Beherrschung von Störungen geht. Es wird eine Methode zur Verhinderung des Kondensationsschlages vorgeschlagen. Sie besteht in der Einführung einer Hilfsarmatur, die sich hinter der eigentlichen Absperrarmatur befindet. Diese Hilfsarmatur wird zu dem Zeitpunkt geschlossen, an dem die Kavitationsblase ihre größte Ausdehnung in der Rohrleitung erreicht hat. Die Blase wird dadurch zwischen den beiden Armaturen eingeschlossen und so am Kollabieren gehindert. Im Vortrag werden die Meßergebnisse vorgestellt, die Rohrleitungs-Versuchsfeld von Fraunhofer UMSICHT mit Zweiphasen-Meßtechnik aus Rossendorf erhalten wurden. Die Auslegungskriterien für eine solche Anordnung werden diskutiert.

The first synthesis of 1-(1,2-dihydro-2-acenaphthylenyl)piperazine (5) – a new arylpiperazine is described. Preliminary binding studies on this new arylpiperazine reveal affinity for the 5-HT_1A and 5-HT_2A receptor subtypes. Incorporation of a dopamine pharmacophore onto this arylpiperazine provided compound (7) a potential antipsychotic with an atypical profile.

In a systematic experimental study of K$^{+}$ and K$^{-}$ production at energies close to and below the free nucleon-nucleon production threshold we have found several features indicating a change of kaon properties within the nuclear medium.

Plasma immersion ion implantation (PIII) on an industrial scale requires negative high voltage pulses in the kA range with voltages up to 200 kV. Hence, the equipment to produce suitable high voltage pulses is rather expensive and shares a considerable part of the total costs of PIII equipment. Reducing the costs of equipment is therefore still a challenge to promote the commercial use of PIII.
A new high voltage modulator is presented, which will meet the above requirements.
The basic idea of the new modulator is that in case of two floating electrodes, immersed into a plasma and connected to both plates of a charged capacitor, the anode potential will be close to the plasma potential, whereas the cathode potential will become negative compared to the plasma potential.
The new modulator works as a triode system, consisting of anode, cathode and grid, all located inside of the working chamber. The plasma is discharged between cathode and grid. As usual in PIII, the sample is immersed into the plasma and works as the cathode in the system. The grid is mounted between plasma and anode, in such a way that ions or electrons from the plasma can get to the anode by passing the grid plane only. Further a capacitor is connected to anode and cathode with both plates and the anode is additionally linked to a positive high voltage source. If the grid is negatively biased, the anode is isolated from the plasma, as electrons from the plasma are reflected by the grid bias, whereas the ions are reflected by the positive potential of the anode. As far as the grid is negatively biased the cathode is at plasma floating potential, and the capacitor may be charged by the positive high voltage source to the capacitor voltage. When the grid potential is switched to ground potential electrons from the plasma can reach the anode and will shift the anode potential to plasma potential. At the same time the cathode is switched to negative high voltage potential .
As the performance of the integrated modulator depends on the maximum of the electron current which can be extracted from the plasma by the anode, the basic considerations concerning the anode current and the revealing design parameters of the integrated modulator are given. The experimental results of modulating 20 kV at a maximum current of 4 A confirm the theory.

In Sachsen waren Ende 1998 Windenergieanlagen (WEA) mit einer installierten Leistung von etwa 140 MW in Betrieb. Als entscheidend für die sehr dynamische Entwicklung ist der in den letzten 10 Jahren erreichte technologische Stand der WEA anzusehen, der wesentlich durch die erreichte Leistungsgrößen (1,5 MW) und die Turmhöhen (60 m bis 80 m) sowie den Übergang zur Serienfertigung charakterisiert wird. Durch die damit verbundene Kostenreduktion steht die Windenergietechnik heute an der Schwelle zur Wirtschaftlichkeit.
Das auf der Basis eines mehrjährigen Meßprogramms ermittelte Windenergiepotential Sachsens liegt mit etwa 5 TWh bei 30 % des sächsischen Stromverbrauches. Bei einem Lastfaktor von 20 % entspricht dies einer installierten Leistung von etwa 3000 MW.
Die Auswertung der monatlichen Erträge von sächsischen WEA bestätigt den angegebenen Lastfaktor im Mittel. Die beobachteten Ertragsunterschiede zwischen einzelnen Standorten von mehr als dem Faktor 2 zeigen die Notwendigkeit, der Standortbewertung größere Aufmerksamkeit zu schenken. Hier besteht weiterer Forschungsbedarf.

The synthesis of the new and highly reactive ¹¹C-precursor triphenylarsonium [¹¹C]methylide 1 and its conversion into [2-¹¹C]indole 6 is described. [¹¹C]Methyltriphenylarsonium iodide 4 was prepared by quaternization of triphenylarsine 2 with [¹¹C]methyl iodide 3 in a THF/DMSO mixture or ethanol. Starting from 3 [¹¹C]methyltriphenylarsonium iodide 4 was obtained in a decay-corrected radiochemical yield of 55%-64% depending on the reaction solvent. The arsonium ylide 1 was prepared in situ by treatment of 4 with butyllithium. Conversion of 1 with o-aminobenzaldehyde 5 in THF/DMSO mixtures yielded [2-¹¹C]indole 6 in radiochemical yields of 23-27% (decay-corrected, in relation to 3). Preparation of 6 was completed after 15 – 20 min (starting from 3). The specific radioactivity of 6 was about 37 GBq/µmol (1 Ci/µmol, related to EOB).

Im Vortrag werden ausgewählte Ergebnisse des 1000-Dächer-Programms zusammengefaßt, die für den Entwurf und die Energieerträge künftiger netzgekoppelter Anlagen relevant sind. Eine kritische Auswertung der Ergebnisse im hier relevanten Leistungsbereich (1-5 kWp) führt relativ zwangsläufig zum Konzept der Einstrang-Anlage. Der DC-Trennschalter kann - ebenso wie die Überspannungsableiter - in das Netzeinspeisegerät integriert werden. Ein künftiges integriertes Netzeinspeisegerät sollte neben dem Wechselrichter noch eine Diagnose- sowie Anzeigeeinheit, die neben Strom-, Spannungs-und Leistungswerten mittels eines einfachen Solarimeters das Performance Ratio errechnet und anzeigt, enthalten. Neben dem Anlagenkonzept ist die Auswahl der Komponenten entscheidend für die erreichbaren Erträge. Bei Nutzung von Modulen mit garantierter STC-Leistung und von Wechselrichtern mit hohem Jahresnutzungsgrad kann ein jährlicher Ertrag von 800 bis 850 kWh pro installierte Generatorleistung von 1 kW erwartet werden. Eine Anlage mit einer Leistung von 5 kW kann demnach den Bedarf eines Durchschnittshaushaltes rechnerisch decken.

Estradiols are able to form two monosulphamates and one disulphamate. In the present work all the sulphamates of 17alpha-estradiol, 17beta-estradiol and 16alpha-fluoroestradiol were synthesized and characterized. For characterization NMR spectroscopy was used first of all. Because of its high sulphatase inhibitory efficiency and 16alpha-fluoroestradiol-3,17beta-disulphamate found a special interest among the new sulphamates. Just the binding between sulphamate and sulphatase favoured 16alpha-[¹⁸F]fluorestradiol-3,17beta-disulphamate to a new radiopharmaceutical which should be appropriate to image the active sites of sulphatase by positron emission tomography. The preparation of 16alpha[¹⁸F]fluoroestradiol-3,17beta-disulphamate requires a simple and rapid procedure. The conditions for such a procedure were also elaborated using non-radioactive substances.

2^nd Workshop on Kaon Production
During the fall of 1996 an internal mini-workshop on kaon production was organized at Rossendorf (cf. FZR-150 [September 19961). The aim of this first workshop was to give a survey on the experimental and theoretical Status of kaon production in elementary hadron reactions and in heavy-ion collisions. Since then the Department of Hadron Physics in the Institute of Nuclear and Hadron Physics of the FZR focused in its research activities on nearthreshold strangeness production in colliding hadron systems and on activities devoted to studies with electromagnetic probes.
Since 1996 a considerable Progress has been achieved in the field. New results from COSY (COSY-11, ToF, COSY-13 and first runs at ANKE) as well as SIS (KaoS and FOPI) allow to determine various elementary cross sections in hadron reactions and kaon yields from heavy-ion collisions. These new results led us to organize a second workshop bringing together the experts of these experiments and various theoreticians. An important purpose of the workshop was to enforce the mutual information and to demonstrate the close interrelation of COSY physics and the heavy-ion programme at SIS. Highlights in the field are (i) the consolidation of the need of strong in-medium modifications to describe the K^- production in heavy-ion reactions and (ii) refined measurements of various elementary strangeness channels near threshold. For the latter the role of final state interactions must be clarified ta arrive at a unique input to transport-model calculations for heavy-ion reactions. Many experimental aspects included in the programme have been proposed by P. Senger (GSI), whereas the composition of its theoretical part benefitted a lot from the support by J. Aichelin (Nantes).

Ausgehend von einer Untersuchung der Einbettung des Urans in die Sedimente, konnte für das Radium abgeleitet werden, daß es wesentlich durch Sorption gebunden in der Matrix vorliegt. Gestützt wird dies durch Freisetzungsuntersuchungen, die bei den vererzten Gesteinen und bei mit Ra beladenen Sedimenten eine Anbindung überwiegend durch Ionenaustausch an tonige Bestandteile ausweisen. In den gelaugten Sedimenten dagegen erfolgt eine Freisetzung von Ra- und Ba-Ionen durch Komplexbildner, was für deren gemeinsame sulfatische Ablagerung spricht.
Für die wäßrigen Phasen ist charakteristisch, daß in den Laugungs- und Flutungslösungen ein Sättigungszustand bezüglich des Bariumsulfats vorliegt, der Ursache für eine Radiumfreisetzung im Verlaufe des Flutungsprozesses ist.
Für die Radiumsorption an den Sedimenten wurden in mehreren Serien Verteilungsverhältnisse bestimmt, die die Grundlage sowohl für eine Abschätzung der Radium-entwicklung in der Flutungslösung (< 50 Bq/l bei Einstauende) als auch der Modellierung der Transportprozesse beim Aufstieg kontaminierter Wässer in den 3. Grundwasserleiter bildeten.
Migrationsuntersuchungen an kleinen Laborsäulen unter Anwendung der Drainagelösung ergaben beim Sandstein eine höhere Mobilität als aus den Batch-Untersuchungen zu erwarten war. Im Falle des Pläners und Tonsteins entsprach das Retardationsverhalten den Ergebnissen der Verteilungsuntersuchungen.
Eindimensionale Transportmodellierungen unter Anwendung der experimentell bestimmten Verteilungsverhältnisse ergab kurze Ausbreitungsstrecken im Grundwasserstauer unter den Bedingungen der Drainagelösung und einen Anstieg der Migrationsdistanzen im 3. Grundwasserleiter beim Übergang von der Drainagelösung zum Grundwasser, wobei eine maximale Transportstrecke von 1.5 km resultiert.

Mit Bezug auf die Stillegung und Sanierung der Uranbergwerke Schlema-Alberoda im Westerzgebirge und Königstein im Elbsandsteingebirge wurde (1) der Abbau des Grubenholzes im Kontakt mit dem Flutungswasser und (2) der Einfluß der gelösten
organischen Holzabbauprodukte auf den chemischen Zustand, die Sorption und das Ausbreitungsverhalten von U(VI), Th(IV), Pb(II) und Fe(III) grundlegend untersucht.

Fe/Al multilayers are prepared by crossed-beam pulsed laser deposition and investigated by Rutherford backscattering, conversion electron Mössbauer spectroscopy and transmission electron microscopy. The
results are compared with purely ballistic simulations of the deposition process using the TRIYDN4.0 code. It is found that the intermixing of adjacent layers must be decribed in terms of ballistic mixing followed
by chemical mixing. The phase build-up in the transition layer between adjacent layers follows the non-equilibrium behaviour of Fe/Al in analogy to investigations on mechanically alloyed and ion-beam mixed Fe/Al. In
Fe-rich areas a bcc-solid-solution is formed. In Al-rich environment an amorphous phase is observed.

Außerhalb und innerhalb eines Gefäßes wird Schall gemessen. Der Quotient aus den Fourier-Spektren beider Signale ist unabhängig von der Schallquelle. Dieser Quotient wird deshalb ausgenutzt, um den Füllstand im Gefäß zu klassifizieren.

Noise is measured inside and outside of a vessel. The quotient of the Fourier-spectra of both signals is independent of the source of noise. That's why the quotient is used to classify the content level in the vessel.

Vertical two-phase flow is normally classified into the four basic flow regimes bubble, slug, churn and annular flow. The transition between the different flow regimes does not occur suddenly and many extensions of this classification can be found in literature. For the prediction of flow patterns empirical and theoretical flow pattern maps have been developed.
A new criterion is presented for the transition between bubble and slug flow which is based on local instantaneous conductivity measurements with a wire mesh sensor (1 kHz that means 1000 frames per second, 242 measuring points in a tube cross section area). The high resolution allows the calculation of particle size distributions.

The transition from homogeneous bubble flow to heterogeneous bubble flow is indicated by the appearance of a bimodal bubble size distribution. If the equivalent bubble diameter exceeds the tube diameter the transition from bubble to slug flow occurs. The new criterion is compared with different empirical (Govier & Aziz, Weisman & Kang) and theoretical flow maps (Taitel, Bornea & Dukler, Ishii & Mishima) and shows a good agreement.

We have investigated the complexation behavior of natural humic acids (HA) with model substances. Our synthetic HA model substance, prepared from glutamic acid and xylose, shows operational properties comparable to those of natural HA in terms of water solubility at different pH and in the type and number of its functional groups. We investigated its complexation behavior with the UO₂ ²⁺ ion by time-resolved laser-induced fluorescence spectroscopy. For comparison, we used purified natural HA from Fluka and Aldrich. The experimental data were evaluated applying the metal ion charge neutralization model developed by Kim and Czerwinski. For our synthetic product, we determined a loading capacity of 23 ± 4 % and a complexation constant of log beta = 6.16 ± 0.22 (pH 3.90 ± 0.05; I: 0.1 M NaClO₄). The obtained values are comparable with experimental results determined for Fluka and Aldrich HA. These results lead to the conclusion that our synthetic product appropriately models the functionality of natural HA.

The report gives an overview on the scientific work of the Institute of Safety Research in 1997.

Dieser Bericht ist für mit den Grundlagen der Monte-Carlo Methode vertraute Leser bestimmt. Von Interesse für solche Leser könnten erfolgreiche Verallgemeinerungen und neue Ideen zur Verbesserung der statistischen Fehler sein. Andrerseits sollen die wichtigsten Grundlagen des Vielgruppen-Monte-Carlo Programms TRAMO dargestellt und das Programm einschließlich notwendiger Eingabe so weit beschrieben werden, daß man nach in jedem Fall notwendige Anpassung an die spezielle Rechentechnik eine wesentliche Grundlage für die Durchführung eigenständiger Rechnungen hat.
Für die meisten Probleme unumgängliches Hilfsmittel für TRAMO ist ein Programm, welches für die Anwendung der varianzreduzierenden "Weight Window Method" die notwendigen Gewichte berechnet (Monte-Carlo Programm TRAWEI), sowie Programme zur Erzeugung der Neutronenquerschnittsdaten und Gruppendaten.
Das Programm TRAMO berechnet bei gegebener Quellverteilung von Neutronen in Vielgruppennäherung Vielgruppenflüsse, integrierte Gruppenflüsse und Dosiswerte für vorgegebene Teilvolumina und Flächen. Es gibt weitere Programmversionen zur Berechnung von Neutronen- und Gammaflüssen sowie zur Kritikalität, welche jedoch nicht Gegenstand dieses Berichtes sind.
Das Vorläuferprogramm von TRAMO war das Programm SMO [1]. Eine fortgeschrittene Version, bereits unter dem Namen TRAMO, wurde in [2] dargestellt. Das hier beschriebene Programm ist wesentlich verallgemeinert und verbessert, umfangreich getestet und für eine große Zahl von Problemen angewendet worden, vor allem für Abschirmungsberechnungen und für Berechnungen von Neutronenfluenzen (siehe [3-5]).
Die oben erwähnten Voraussetzungen für die Nutzung des Programms sind die Bereitstellung von Gruppendaten (Nutzung des international gebräuchlichen Programms NJOY und eigenen Programmen, siehe Abschnitt 1 bzw. 6), die Berechnung von geeigneten Gewichtsfunktionen (Monte-Carlo Programm TRAWEI, siehe Abschnitt 3 bzw. Abschnitt 5) und die genaue Kenntnis der im Programm TRAMO gegebenen Möglichkeiten.
In Abschnitt 1 wird auf die Versorgung mit Neutronendaten eingegangen, Abschnitt 2 beschreibt die Möglichkeiten von TRAMO, in Abschnitt 3 werden die varianzreduzierenden Methoden beschrieben, vor allem wird hier auf die Grundlagen des Programms TRAWEI zur Berechnung der Gewichte ("Weight Window Method") Bezug genommen.
Abschnitt 4 gibt eine Eingabebeschreibung des Programms TRAMO, in Abschnitt 5 wird auf die Handhabung von TRAWEI eingegangen, und Abschnitt 6 befaßt sich mit Programmen zur Neutronengruppendatenerzeugung bzw. abgeleiteter Größen in einem für das Programm TRAMO geeigneten Format und in 7 wird auf das Hilfsprogramm SUMMA zur Zusammenfassung von Ergebnissen bei Anwendung von Parallelrechnung eingegangen.

Betrachtet werden Prozesse, in denen Teilprozesse voneinander abgrenzbar sind, die unabhängig voneinander zur Komplexität des Prozeßmodellfehlers beitragen. Auf der Grundlage von Dimensionsbetrachtungen wird versucht, die zu den Teilprozessen gehörenden Teilmodelle, d.h. die Elemente der Modellstruktur des Prozesses einzeln zu bestimmen. Ein Gesamtmodell des Prozesses soll auf diese Weise zielgerichteter als mit herkömmlichen Methoden gebildet werden können. Zur qualitativen Erfassung des Modellfehlers wird anhand von Ansätzen aus der Dimensionsanalyse, einem Bestandteil der Ähnlichkeitstheorie, ein Fehlermodell definiert. Zur quantitativen Erfassung der Komplexität des Modellfehlers werden dimensionsähnliche Kenngrößen eingeführt, die von einer Variante der fraktalen Dimension, der Zirkel- oder Liniendimension ausgehen.

Abstract.
The elastic backward proton-deuteron scattering is analyzed within a covariant approach based on the Bethe-Salpeter equation with realistic meson-exchange interaction. Contributions of the one-nucleon and one-pion exchange mechanisms to the cross section and polarization observables are investigated in explicit form. Results of numerical calculations for the cross section, tensor analyzing power and spin transfers are presented. The one-pion exchange contribution is essential for describing the spin averaged cross section, while in polarization observables it is found to be less important.

The genus Bacillus consists of more than 70 species of Gram-positive, aerobic or facultatively anaerobic spore-forming rod-shaped bacteria. Because of the high resistance of their spores, Bacilli were found in a large variety of natural habitats. For our accumulation studies with U(VI), we used vegetative cells and spores of three Bacillus isolates (JG-A 30, JG-A 12, JG-A 22, classified as Bacillus cereus, Bacillus sphaericus, Bacillus megaterium) from a uranium mining waste pile (Johanngeorgenstadt, Saxony) and their corresponding reference strains. Sorption studies at pH 5.0 have shown that in the concentration range examined (11 – 214 mg/L) Bacilli accumulate high amounts of uranium. Information on the binding strength and the reversibility were obtained from extraction studies with different extractants. With 0.01 M EDTA solution the uranium bound to the biomass was released almost quantitatively. The characterization of the bacterial-UO22+-complexes by time-resolved laser fluorescence spectroscopy (TRLFS) has proved the formation of inner-sphere complexes with the biomass. At pH 5 a ternary complex of uranyl with the biomass and hydroxide in solution was detected. After cell fractionation, we examined the spectroscopic properties of the U(VI)-complexes with the isolated cell walls and the isolated surface-layer protein fraction of the bacteria. Spectroscopic studies of these complexes have shown that with intact cells (vegetative cells or spores) the complexation of U(VI) is stronger than with isolated cell wall components. Therefore, the good complexation properties, the easy release of the bound uranium by EDTA-extraction, and the high resistance against harsh environmental conditions makes these bacteria applicable for bioremediation purposes.

Die zeitaufgelöste laserinduzierte Fluoreszenzspektroskopie (TRLFS) wird schon seit längerem als äußerst sensitive Methode zur Untersuchung der Komplexbildung von Radionukliden mit organischen und anorganischen Liganden eingesetzt. Hier sind insbesondere Untersuchungen an Uran(VI) und Cm(III) mit Huminsäuren zu nennen. Jedoch sind die bisher angewandte TRLFS-Techniken mit Anregungspulsen im Nanosekundenbereich nur auf Radionuklide mit Fluoreszenzeigenschaften beschränkt /1/. Die
Entwicklung und Anwendung einer TRLFS mit ultrakurzen Anregungspulsen, d.h. mit Pulsen im Pico- und emtosekundenbereich, eröffnet die Möglichkeit die Komplexbildung von nichtfluoreszierenden, umweltrelevanten Radionukliden, wie z. B. Neptunium, mit organischen Liganden über die Veränderung der Fluoreszenz-eigenschaften der Liganden zu untersuchen.
Ein erster Schritt für die Anwendung der TRLFS mit ultrakurzen Pulsen besteht im Aufbau eines solchen Lasersystem. Das neue Rossendorfer Lasersystem nutzt einen zweifach verstärkten Puls mit einer Pulsdauer von 130 fs eines mode-locked Ti:Sapphire Oszillators als Anregungspuls /2/. Die Auswahl der optimalen Anregungswellenlänge erfolgt über ein durchstimmbares estkörperlasersystem (OPA-System) zwischen 250 nm und 10 µm. Das Fluoreszenzlicht der Probe wird direkt in einen
Gitterspektrographen eingekoppelt, die Detektion des Fluoreszenzsignals erfolgt mit einer intensivierten CCD Kamera.
Zuerst wurden die Fluoreszenzeigenschaften (Fluoreszenzlebensdauer, Fluoreszenzintensität und -spektrum) von verschiedenen Huminsäuren untersucht. Dabei wurden die Probenparameter (pH-Wert, Konzentration,Ionenstärke) und verschiedene Systemparameter, wie z. B. Anregungswellenlänge, variiert. Das mit der bisherigen Lasertechnik sehr gut charakterisierte Komplexsystem Uran(VI) und Huminsäure /3/ wurde für eine Validierung des Femtosekunden-Lasersystems verwendet. Die
Ergebnisse der vergleichenden Messungen werden diskutiert.

A more detailed survey of modern methods for characterizing radionuclides and heavy metals in the environment and for elucidating the mechanisms of their interaction with biomolecules is given.
Laser-induced spectroscopies, including Time-Resolved Laser Fluorescence (TRLFS), Photoacustic (LIPAS), Thermal Lensing (LITLS) and Photothermal Deflection Spectroscopy (LIPDS) provide the identification of the chemical species of radionuclides and heavy metals in environmental media in concentrations down to the micro-molar range and even lower. This includes information on the oxidation state, the stöchiometry, and the structure of ions and dissolved complexes, including the discrimination between ionic and polynuclear or colloidal species that may preferentially be built with thorium, uranium and plutonium.
The complexes formed with the biomolecules as the result of the metal incorporation can be studied by X-ray absorption spectroscopies using synchrotron radiation, such as X-ray Absorption Near Edge Spectroscopy (XANES) and Extended X-ray Absorption Fine Structure. These methods give information on the valency and the coordination of the central ion as well as on the bond length to neighboring atoms, leading to an initial understanding of the spatial orientation and structure. This knowledge is essential to describe the interaction of radionuclides, such as U, Th, Ra, Np, Pu, Am, Cm, Zr, Sr, Cs and Tc with biomolecules and biomass. The selenium uptake by the soil bacterium Bacillus subtilis is cited as an example: from XANES spectra, the absorption process could be proved as an incorporation into the cell membrane under reduction of selenium(IV) to zerovalent selenium. From both the identified species and the characterized final complex, conclusions can be drawn regarding the overall absorption mechanism. These information are essential for selecting and optimizing biomolecular systems intended for environmental remediation purposes.

Mit Bezug auf die Flutung von Bergwerken im sächsischen Raum wurden die Redoxeigenschaften von natürlichen Polyelektrolyten, wie Holzabbauprodukten, Lignin und Huminsäuren und die Reduktion von Eisen(III) und Uran(VI) durch diese Polyelektrolyte untersucht. Außerdem wurde die Adsorption von Eisen(II,III) und Uran(IV,VI) aus Flutungswässern an grubentypischen Gesteinen und Sedimenten unter anaeroben Bedingungen bei Anwesenheit der organischen Substanzen untersucht. (Juni 1998)

Annual Report 1998
Institute of Radiochemistry

Der Rothschönberger Stolln ist der Hauptentwässerungsstollen des aufgelassenen Freiberger Bergbaureviers. An seinem Mundloch enthält sein Wasser etwa 1 mg/l an kolloidalen Partikeln des Größenbereichs 75 bis 300 nm. Die Partikel bestehen vor allem aus Eisen- und Aluminiumoxidhydroxid, tragen aber auch Spurenelemente (Pb, As, Cu, Y, La). Die Schadstoffe Pb und As z. B. sind im Rothschönberger Stolln nahezu vollständig an Kolloide gebunden. Das Uranium dagegen liegt in nichtkolloidaler Form (echt gelöst) vor; wahrscheinlich sind dafür Karbonatkomplexe des Uranylions verantwortlich. Nach Absenken des pH-Wertes auf etwa 5 (Zerstörung der Karbonatkomplexe) waren erhebliche Mengen des Uraniums an Kolloide gebunden. Letzteres besitzt Bedeutung für die Beurteilung des Verhaltens von Uranium in sauren Grubenwässern, wie z. B. in Wässern der Urangrube Königstein. Speziationsrechnungen mit Hilfe des thermodynamischen Geochemie-Rechenprogramms EQ6 stimmen zunächst schlecht mit den experimentellen Befunden überein. Die vom Experiment abweichenden Rechenergebnisse können jedoch leicht aus einer unzureichenden Berücksichtigung der Kinetik im chemischen Modell erklärt werden. Die Versuche zeigen Wege auf, wie Modellrechnungen mit EQ6 "praxisnäher" gemacht werden können.

The SWR1000 is a new innovative boiling water reactor concept, which is developed by Siemens AG. This concept is characterized in particular by passive safety systems (e.g. four emergency condensers, four building condensers, eight passive pressure pulse transmitters, six gravity-driven core flooding lines). In the framework of BWR Physics and Thermohydraulic Complementary Action (BWR-CA) to the EU BWR R&D Cluster emergency condenser tests were performed by Forschungszentrum Jülich at the NOKO test facility. In this paper post test calculations with ATHLET are presented, which aim at the determination of the removable power of the emergency condenser and its operation mode. The 1D thermal-hydraulic code ATHLET was extended by the module KONWAR for the calculation of the heat transfer coefficient during condensation in horizontal tubes. In addition, results of CFD-calculations using the code CFX-4 are presented, which investigate the natural convection during the heat up process at the secondary side of the NOKO test facility.

The condensation in horizontal tubes plays an important role e.g. for the determination of the operation mode of horizontal steam generators of VVER reactors or passive safety systems for the next generation of nuclear power plants. Two different approaches (HOTKON and KONWAR) for modeling this process have been undertaken by Forschungszentrum Jülich (FZJ) and University for Applied Sciences Zittau/Görlitz (HTWS) and implemented into the 1D-thermohydraulic code ATHLET, which is developed by the Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbH for the analysis of anticipated and abnormal transients in light water reactors.
Although the improvements of the condensation models are developed for different applications (VVER steam generators - emergency condenser of the SWR1000) with strongly different operation conditions (e.g. the temperature difference over the tube wall in HORUS is up to 30 K and in NOKO up to 250 K, the heat flux density in HORUS is up to 40 kW/m² and in NOKO up to 1 GW/m²) both models are now compared and assessed by Forschungszentrum Rossendorf FZR e.V. Therefore post test calculations of four selected HORUS experiments were performed with ATHLET/KONWAR. It can be seen that the calculations with the extension KONWAR as well as HOTKON improve significantly the agreement between computational and experimental data.

Abstract: The status of the ELBE FEL projects is reviewed. ü

The mass distributions of baryon resonances populated in near-central collisions of Au on Au and Ni on Ni are deduced by defolding the p_t spectra of charged pions by a method which does not depend on a specific resonance shape. In addition the mass distribution of resonances are obtained from the invariant masses of (p,π^±) pairs. With both methods the deduced mass distribution are shifted by an average value of -60 MeV/c² relative to the mass distribution of the free Δ(1232) resonance, the distribution descent almost exponentially towards mass values of 2000 MeV/c². The observed differences between (p,π^-) and (p,π⁺) pairs indicate a contribution of isospin I=1/2 resonances. The attempt to consistently describe the deduced mass distributions and the reconstructed kinetic energy spectra of the resonances leads to new insights about the freeze out conditions, i.e. to rather low temperatures and large expansion velocities.

For developing a dihydropyridine/pyridinium salt redox delivery system that could be useful for SPECT investigations by ^99mTc compounds the synthesis of a mixed-ligand complex of the long-lived isotope ⁹⁹Tc is described. The new compound bearing a pyridinium salt moiety was characterised by NMR-spectrometry and X-ray structure analysis. By reduction with sodium dithionite the corresponding 1,4-dihydropyridine complex was prepared and the stability in buffer, tissue homogenates, blood plasma and cerebrospinal fluid was investigated by UV-VIS spectrometry.

Die Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbH entwickelt das Programmsystem ATHLET (Analyse der Thermohydraulik bei Lecks und Transienten) mit der Zielsetzung, das gesamte Spektrum von Kühlmittelverlust- und Transientenstörfällen in Leichtwasserreaktoren berechnen zu können. Voraussetzung hierzu ist jedoch, daß die in ATHLET enthaltenen Modelle in der Lage sind, die hierbei auftretenden Phänomene prinzipiell beschreiben zu können.
Speziell bei WWER-Reaktoren sowie dem SWR1000 treten konstruktive Besonderheiten auf (z. B. beim WWER die Leitungsführung der Hauptkühlmittelleitungen mit je einer Absenkung im heißen und kalten Strang, liegende Dampferzeuger, beim SWR1000 die horizontalen Notkondensatorbündel). Die im Rahmen des BMBF Projektes Nr. 150 0856 8 "Verifikation des Rechencodes ATHLET" [2] von der Hochschule Zittau/Görlitz (HTWS) durchgeführte unabhängige ATHLET-Verifikation und die "Berechnung des passiven Notkondensators eines mit Naturumlauf arbeitenden innovativen Siedewasserreaktors (SWR600) mit ATHLET" (BMBF Projek 15 NU 09485) der Forschungszentrum Jülich (FZJ) GmbH zeigen übereinstimmend, daß das in ATHLET enthaltene Kondensationsmodell für die Simulation der Kondensation innerhalb liegender Rohre ungünstig ist.
Daher wurden in beiden Organisationen umfangreiche Erweiterungen des Kondensationsmodells (HOTKON - HTWS, KONWAR - FZJ) vorgeschlagen, realisiert und anhand von HORUS- bzw. NOKO-Experimenten validiert. Die beiden Experimente unterscheiden sich jedoch hinsichtlich ihrer Betriebsparameter. Zielsetzung der dieser Veröffentlichung zugrunde liegenden Arbeiten ist, KONWAR anhand von HORUS-Experimenten zu validieren und die Rechenergebnisse mit der um KONWAR erweiterten ATHLET-Version mit den experimen-tellen Daten sowie den Rechenergebnissen der Original und um HOTKON erweiterten Version von ATHLET zu vergleichen.

Es wird ein neuerrichtetes Radionuklidlaboratorium zur Untersuchung bestrahlter Werkstoffproben vorgestellt und das Spektrum der gegebenen Untersuchungsmöglichkeiten vorgestellt.

no abstract

Der Einfluss von Kupfer, Phosphor und Nickel auf die Neutronenversprödung wird anhand von 8 Testlegierungen untersucht. Die Testlegierungen sind bis zu Neutronenfluenzen von 1x10¹⁹ und 8x10¹⁹ N/cm² [E>0.5 MeV] bei 270 °C in WWER-440-Reaktoren bestrahlt worden. Sowohl Ni als auch P und Cu erhöhen die Bestrahlungsempfindlichkeit. Eine überraschend hohe Bestrahlungsempfindlichkeit zeigt eine Fe-Mn-Si-Legierung hoher Reinheit.

Radionuclide concentrations have been determined by gamma-ray spectrometry in rock samples taken from a forty-years old uranium waste rock pile. With increasing depth, an increase of the Ra-226/U-238 activity ration was found. This can be explained by different migration rates of the individual nuclides.

Experiments were performed to investigate heating up processes of fluids in storage tanks under the in-fluence of an external heat source. As a con-se-quence of an external fire, the heat-up of the inventory may lead to the evaporation of the liquid and to release of significant quan-tities of dan-ge-rous gases into the envi-ron-ment. Several tests were performed both with heating from the bottom and with heating from the side walls. In recent tests in addition to thermocouples, the tank was equipped with needle probes for measuring of the local void fraction.
The paper presents experimental and numerical investigations of single and two phase heating up processes of tanks with side wall heating. The measurement of the temperature and of the void fraction makes interesting phenomena evident. which could be explained by an own 2D model. The gained experimental results may be used for the validation of boiling models in 3-D CFD codes.

A one-dimensional model for multiphase flow in a vessel was developed. The model bases on a new particle method and is free of numerical diffusion. This allows a consistent simulation of discontinuities such as the top level of the mixture without additional level tracking methods. The model distinguishes between continuous and dispersed phases. Levels mark the locations where the continuous phase change. This model for multiphase transport is the basic component of a new computer code. Flexible interfaces allow a convenient coupling of this model with constitutive laws for special phenomena. A special goal of the code is the transient simulation of emergency relief from chemical reactors with consideration of foam. For this reason the code was equiped with models for pressure calculation, conservation of energy, phase transfer, bubble generation, bubble growth, coalescence, drift of the phases, heat release from the vessel wall, discharge and homogeneous chemical reactions. A special interface, which enables the modelling of generation and decay of foam at the top level of the mixture, is included. Any of the phases can consist of several components. The code was validated for numerous depressurization experiments.

The process in the anode chamber of an alkaline chloride electrolysis cell was modelled by hydrogen peroxide decomposition at a platinum surface, which replaces the anode. Bubble size measurements and shutdown experiments have shown the ap-plicability of this model reaction. In the anode chamber regions of bubble flow, spherical foam and a transition to cell foam at the top were found. Gas fraction distributions were measured by the differential pressure method and gamma densitometry. LDA and PDPA were used to obtain velocity and bubble size distributions. For the bubble flow region, the correct consideration of the bubble size distribution was identified as determining factor to reproduce the volume flow rate of the gaseous phase from the measured gas fraction. Minor contributions to the gas flow rate are caused by bubbles of several millimetres magnitude generated in the ribs of the anode and by a liquid circulation driven by the lateral gas supply, which is characteristic for the design of membrane cells. In the foam region, large bubbles appearing as a result of coalescence carry a significant part of the gas flow rate.