THEREDA (Thermodynamic Reference Database) is a collaborative project, which has been addressed this challenge. The partners are Helmholtz-Zentrum Dresden-Rossendorf, Karlsruhe Institute of Technology (KIT-INE), Gesellschaft für Anlagen- und Reaktorsicherheit Braunschweig mbH (GRS), TU Bergakademie Freiberg (TUBAF) and AF-Consult Switzerland AG (Baden, Switzerland). The aim of the project is the establishment of a consistent and quality assured database for all safety relevant elements, temperature and pressure ranges, with its focus on saline systems. This implied the use of the Pitzer approach to compute activity coefficients suitable for such conditions. Data access is possible via commonly available internet browsers under the address http://www.thereda.de. One part of the project - the data collection and evaluation for uranium – was a task of the Helmholtz-Zentrum Dresden-Rossendorf. The aquatic chemistry and thermodynamics of U(VI) and U(IV) is of great importance for geochemical modelling in repository-relevant systems. The OECD/NEA Thermochemical Database (NEA TDB) compilation is the major source for thermodynamic data of the aqueous and solid uranium species, even though this data selection does not utilize the Pitzer model for the ionic strength effect correction. As a result of the very stringent quality demands, the NEA TDB is rather restrictive and therefore incomplete for extensive modelling calculations of real systems. Therefore, the THEREDA compilation includes additional thermodynamic data of solid secondary phases formed in the waste material, the backfill and the host rock, though falling into quality assessment (QA) categories of lower accuracy. The data review process prefers log K values from solubility experiments (if available) to those calculated from thermochemical data.

Direct Contact Condensation between steam and water as well as bubble entrainment below the water surface play an important role in different accident scenarios for light water reactors. One example is the emergency core cooling water injection into a two-phase mixture. It has to be considered for example to evaluate potential pressurized thermal shock phenomena. This report documents experiments conducted in flat basin inside the TOPFLOW pressure chamber aiming on the generation of a database useful for CFD model development and validation. It comprises 3 different setups: condensation at a stratified flow of sub-cooled water, condensation at a sub-cooled water jet and a combination of both phenomena with steam bubble entrainment. The documentation includes all details on the experimental set up, on experimental conditions (experimental matrices), on the conduction of the experiments, on measuring techniques used and on data evaluation procedures. In addition, selected results are presented.

The advantages of contemporary particle injectors are high bunch charges and good beam quality in the case of normal conducting RF guns and increased repetition rates in the one of DC injectors. The technological edge of the concept of superconducting radio frequency injectors is to combine the strengths of both these sides. As many future accelerator concepts, such as energy recovery linacs, high power free electron lasers and certain collider designs, demand particle sources with high bunch charges and high repetition rates combined, applying the superconductivity of the accelerator modules to the injector itself is the next logical step. However, emittance compensation — the cornerstone for high beam quality — in case of a superconducting injector is much more challenging than in the normal conducting one. The use of simple electromagnets generating a solenoid field around the gun’s resonator interferes with its superconducting state. Hence, it requires novel and sophisticated techniques to maintain the high energy gain inside the gun cavity, while at the same time alleviating the detrimental fast transverse emittance growth of the bunch. In the case of the ELBE accelerator at the Helmholtz-Zentrum Dresden-Rossendorf, a superconducting electron accelerator provides beam for several independent beamlines in continuous wave mode. The applications include IR to THz free electron lasers, neutron and positron generation, to Thompson backscattering with an inhouse TW laser, and hence, call for a flexible CW injector. Therefore, the development of a 3.5 cell superconducting electron gun was initiated in 1997. The focus of this thesis lies on three approaches of transverse emittance compensation for this photoinjector: RF focusing, the installation of a superconducting solenoid close to the cavity’s exit, and the introduction of a transverse electrical mode of the RF field in the resonator. All three methods are described in theory, examined by numerical simulation, and experimentally reviewed in the particular case of the ELBE SRF Gun II at HZDR and a copy of its niobium resonator at Thomas Jefferson National Laboratory, Newport News, VA, USA.

Laser plasma wakefield accelerators have seen tremendous progress in the last years, now capable of producing electron beams in the GeV energy range. The inherent few-femtoseconds short bunch duration of these accelerators leads to ultra-high peak-currents. Reducing the energy spread found in these accelerators, while scaling their output to hundreds of kiloampere peak current would stimulate the next generation of radiation sources covering high-field THz, high-brightness X-ray and -ray sources, compact free-electron lasers and laboratory-size beam-driven plasma accelerators. At such high currents, an accelerator operates in the beam loaded regime where the accelerating field is strongly modified by the self-fields of the injected bunch, potentially deteriorating key beam parameters. However, if appropriately controlled, the beam loading effect can be employed to improve the accelerator’s performance, specifically to reduce the energy spread. In this thesis the beam-loading effect is systematically studied at a quasi-monoenergetic nanocoulomb-class laser wakefield accelerator. For this purpose, a tailored scheme of the self-truncated ionisation injection process is introduced for the non-linear bubble regime. This scheme facilitates stable and tunable injection of high-charge electron bunches within a short and limited time-frame, ensuring low energy spread right after injection. Employing a three millimetres gas-jet acceleration medium and a moderate 150 TW short pulse laser system as driver, unprecedented charges of up to 0.5 nC within a quasi-monoenergetic peak and energies of ~0.5 GeV are achieved. Studying the beam loading mechanism, it is demonstrated that at the optimal loading condition, i.e. at a specific amount of injected charge, performance of the accelerator is optimised with a minimisation of the energy spread. At a relative energy spread of only 15%, the associated peak current is around 10 kA, while scaling this scheme to operate with a petawatt driver laser promises peak-currents up to 100 kA.

Moderne Hochdruckforschung entwickelt sich rasant zu einer der vielfältigsten und überraschensten Disziplinen der Festkörperphysik. Unter Benutzung von Diamantstempelzellen können Drücke erreicht werden, die den Bedingungen im Inneren unserer Erde ähneln. Eine Anwendung von Kernmagnetischen Resonanzexperimenten (NMR) in Diamantstempelzellen galt jedoch für lange Zeit als unmöglich. In der vorliegenden Arbeit wird ein neuartiger Ansatz weiterentwickelt, der Radiofrequenz-(RF)-Mikrospulen benutzt, die direkt zwischen den Diamantstempeln platziert werden, und somit zu einer signifikanten Sensitivitätssteigerung führen. Es ist gelungen, Hochdruckzellen zu entwickeln, die für die speziellen Anforderungen der NMR zugeschnitten sind. Des Weiteren konnte eine nicht metallische, nicht magnetische Dichtung entwickelt werden, die zudem zu einer signfifikanten Stabilisierung des Probenvolumens führt. Eine breit angelegte Analyse der Leistungsfähigkeit dieser neuartigen NMR-Hochdruckprobenköpfe zeigt deren Leistungsfähigkeit mit sehr hohen Empfifindlichkeiten sowie einer exzellenten RF Anregung und Zeitauflösung. Drei Anwendungsbeispiele, die das Potenzial dieses Ansatzes in dieser Arbeit unterstreichen, werden vorgestellt. Bei Drücken von bis zu 4 GPa werden die elektronischen und dynamischen Eigenschaften von elementarem Gallium untersucht. Unter höheren Drücken ist es gelungen, einen druckinduzierten Isolator-Metall-Übergang in dem ternären Chalkogenid AgInTe2 zu beobachten. Schlussendlich ist es gelungen, die strukturellen und elektronischen Eigenschaften von Rubin bei Drücken von bis zu 30.5 GPa zu untersuchen, was einer Verdreifachung des bisher zugänglichen experimentellen Druckbereiches entspricht und die NMR für moderne Hochdruckanwendungen möglich macht.

The groundwater bacterium Pseudomonas fluorescens (CCUG 32456) isolated at a depth of 70 m in the Äspö Hard Rock Laboratory secretes a pyoverdin-mixture with four main components (two pyoverdins and two ferribactins). The dominant influence of the pyoverdins of this mixture could be demonstrated by an absorption spectroscopy study. The comparison of the stability constants of U(VI), Cm(III), and Np(V) species with ligands simulating the functional groups of the pyoverdins results in the following order of complex strength: pyoverdins (PYO) > trihydroxamate (DFO) > catecholates (NAP, 6­HQ) > simple hydroxamates (SHA, BHA). The pyoverdin chromophore functionality shows a large affinity to bind actinides. As a result, pyoverdins are also able to complex and to mobilize elements other than Fe(III) at a considerably high efficiency. It is known that EDTA may form the strongest actinide complexes among the various organic components in nuclear wastes. The stability constants of 1:1 species formed between Cm(III) and U(VI) and pyoverdins are by a factor of 1.05 and 1.3, respectively, larger compared to the corresponding EDTA stability constants. The Np(V)-PYO stability constant is even by a factor of 1.83 greater than the EDTA stability constant. The identified Np(V)-PYO species belong to the strongest Np(V) species with organic material reported so far. All identified species influence the actinide speciation within the biologically relevant pH range. The metal binding properties of microbes are mainly determined by functional groups of their cell wall (LPS: Gram-negative bacteria and PG: Gram-positive bacteria). On the basis of the determined stability constants raw estimates are possible, if actinides prefer to interact with the microbial cell wall components or with the secreted pyoverdin bioligands. By taking pH 5 as an example, U(VI)-PYO interactions are slightly stronger than those observed with LPS and PG. For Cm(III) we found a much stronger affinity to aqueous pyoverdin species than to functional groups of the cell wall compartments. A similar behavior was observed for Np(V). This shows the importance of indirect interaction processes between actinides and bioligands secreted by resident microbes.

Realising Si-based electrically driven light emitters in a process technology compatible with mainstream microelectronics CMOS technology is key requirement for the implementation of low-cost Si-based optoelectronics and thus one of the big challenges of semiconductor technology. This work has focused on the development of microcavity enhanced silicon LEDs (MCLEDs), including their design, fabrication, and experimental as well as theoretical analysis. As a light emitting layer the abrupt pn-junction of a Si-diode was used, which was fabricated by ion implantation of boron into n-type silicon. Such forward biased pn-junctions exhibit room-temperature EL at a wavelength of 1138 nm with a reasonably high power efficiency of 0.1% [1]. Two MCLEDs emitting light at the resonant wavelength about 1150 nm were demonstrated: a) 1 MCLED with the resonator formed by 90 nm thin metallic CoSi2 mirror at the bottom and semitranparent distributed Bragg reflector (DBR) on the top; b) 5:5 MCLED with the resonator formed by high reflecting DBR at the bottom and semitransparent top DBR. Using the appoach of the 5:5 MCLED with two DBRs the extraction efficiency is enhanced by about 65% compared to the silicon bulk pn-junction diode.:List of Abbreviations and Symbols 1 Introduction and motivation 2 Theory 2.1 Electronic band structure of semiconductors 2.2 Light emitting diodes (LED) 2.2.1 History of LED 2.2.2 Mechanisms of light emission 2.2.3 Electrical properties of LED 2.2.4 LED e ciency 2.3 Si based light emitters 2.4 Microcavity enhanced light emitting pn-diode 2.4.1 Bragg reflectors 2.4.2 Fabry-Perot resonators 2.4.3 Optical mode density and emission enhancement in coplanar Fabry-Perot resonator 2.4.4 Design and optical properties of a Si microcavity LED 3 Preparation and characterisation methods 3.1 Preparation techniques 3.1.1 Thermal oxidation of silicon 3.1.2 Photolithography 3.1.3 Wet chemical cleaning and etching 3.1.4 Ion implantation 3.1.5 Plasma Enhanced Chemical Vapour Deposition (PECVD) of silicon nitride 3.1.6 Magnetron sputter deposition 3.2 Characterization techniques 3.2.1 Variable Angle Spectroscopic Ellipsometry (VASE) 3.2.2 Fourier Transform Infrared Spectroscopy (FTIR) 3.2.3 Microscopy 3.2.4 Electroluminescence and photoluminescence measurements 4 Experiments, results and discussion 4.1 Used substrates 4.1.1 Silicon substrates 4.1.2 Silicon-On-Insulator (SOI) substrates 4.2 Fabrication and characterization of distributed Bragg reflectors 4.2.1 Deposition and characterization of SiO2 4.2.2 Deposition of Si 4.2.3 Distributed Bragg Reflectors (DBR) 4.2.4 Conclusions 4.3 Design of Si pn-junction LED 4.4 Resonant microcavity LED with CoSi2 bottom mirror 4.4.1 Device preparation 4.4.2 Electrical Si diode characteristics 4.4.3 EL spectra 4.4.4 Conclusions 4.5 Si based microcavity LED with two DBRs 4.5.1 Test device 4.5.2 Device fabrication 4.5.3 LED on SOI versus MCLED 4.5.4 Conclusions 5 Summary and outlook 5.1 Summary 5.2 Outlook A Appendix A.1 The parametrization of optical constants A.1.1 Kramers-Kronig relations A.1.2 Forouhi-Bloomer dispersion formula A.1.3 Tauc-Lorentz dispersion formula A.1.4 Sellmeier dispersion formula A.2 Wafer holder List of publications Acknowledgements Declaration / Versicherung

The tenser analyzing power T-20 and the polarization transfer kappa in the deuteron break-up reaction Dp --> pX are calculated within a relativistic approach based on the Bethe-Salpeter equation with a realistic meson-exchange potential. Our results on T-20, kappa and the cross section are compared with experimental data and non-relativistic calculations and with the outcome of a relativization procedure of the deuteron wave function.

The paper presents results of a research project founded by the Swiss Federal Nuclear Inspectorate concerning the application of the Master Curve approach in nuclear reactor pressure vessels integrity assessment. The main focus is put on the applicability of pre-cracked 0.4T-SE(B) specimens with short cracks, the verification of transferability of MC reference temperatures T0 from 0.4T thick specimens to larger specimens, ascertaining the influence of the specimen type and the test temperature on T0, investigation of the applicability of specimens with electroerosive notches for the fracture toughness testing, and the quantification of the loading rate and specimen type on T0. The test material is a forged ring of steel 22 NiMoCr 3 7 of the uncommissioned German pressurized water reactor Biblis C. SE(B) specimens with different overall sizes (specimen thickness B=0.4T, 0.8T, 1.6T, 3T, fatigue pre-cracked to a/W=0.5 and 20% side-grooved) have comparable T0. T0 varies within the 1σ scatter band. The testing of C(T) specimens results in higher T0 compared to SE(B) specimens. It can be stated that except for the lowest test temperature allowed by ASTM E1921-09a, the T0 values evaluated with specimens tested at different test temperatures are consistent. The testing in the temperature range of T0 ± 20 K is recommended because it gave the highest accuracy. Specimens with a/W=0.3 and a/W=0.5 crack length ratios yield comparable T0. The T0 of EDM notched specimens lie 41 K up to 54 K below the T0 of fatigue pre-cracked specimens. A significant influence of the loading rate on the MC T0 was observed. The HSK AN 425 test procedure is a suitable method to evaluate dynamic MC tests. The reference temperature T0 is eligible to define a reference temperature RTTo for the ASME-KIC reference curve as recommended in the ASME Code Case N-629. An additional margin has to be defined for the specific type of transient to be considered in the RPV integrity assessment. This margin also takes into account the level of available information of the RPV to be assessed.

Der Reaktordynamikcodes DYN3D wurde in der neu entwickelten Mehrgruppen-Version DYN3D-MG für die Anwendung auf wassergekühlte Reaktoren alternativ zu industriellen DWR und SWR ertüch-tigt. Es wurde die Anwendbarkeit für den graphitmoderierten Druckröhrenreaktor EGP-6 (KKW Bilibi-no), eine Konzeptstudie eines fortgeschrittenen Siedewasserreaktors mit schnellem Neutronenspekt-rum (RMWR) und das Reaktorkonzept RUTA-70 zur Wärmeversorgung nachgewiesen. Beim RUTA-Reaktor geht es vor allem um die Modellierung des Naturumlaufs des Kühlmittels bei niedrigen Sys-temdrücken. Zur Validierung wurden Experimente zu flashing-induzierten Naturumlaufinstabilitäten an der Versuchsanlage CIRCUS der TU Delft mit RELAP5 nachgerechnet. Für die Anwendung von DYN3D auf die alternativen Reaktorkonzepte wurden Modellerweiterungen und Anpassungen vorgenommen, u.a. Modifikationen in den Wärmeleitungs- und -übergangsmodellen. Vergleichsrechnungen mit dem stationären russischen Feingitter-Diffusionscode ACADEM ergänzen die Verifikationsdatenbasis von DYN3D-MG. Zur Validierung wurden zwei reak-tordynamische Experimente am Reaktor EGP-6 nachgerechnet. Für Reaktoren EGP-6, RMWR und RUTA wurden verschiedene Transienten mit Ausfahren von Re-gelstäben mit und ohne Reaktorschnellabschaltung gerechnet. Weiterhin wurden Analysen für den ATWS-Störfall \"Abschalten aller Hauptkühlmittelpumpen bei Vollleistung\" für den RUTA-Reaktor mit den gekoppelten Programmkomplexen DYN3D/ATHLET und DYN3D/RELAP5 durchgeführt. Der Reaktor geht in einen sicheren Zustand mit reduzierter Leistung bei Naturumlauf des Kühlmittels über. Die Ergebnisse von Analysen zum unkontrollierten Ausfahren einer Regelgruppe für den RMWR lassen dagegen eine belastbare Schlussfolgerung bezüglich der Beherrschbarkeit des Aus-fahrens einer Regelgruppe nicht zu. Abschließend wurde der Nutzen der Programmertüchtigung von DYN3D für die Anwendung auf GenIV -Konzepte und LWR mit hohem Konversionsfaktor bewertet.