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Eingeladener Vortrag
- nein (84)
Der Transport, die Zwischen- und Endlagerung von nuklearem Material ist ein weltweit bedeutendes Thema. Für das deutsche Konzept zur direkten Endlagerung der abgebrannten Brennelemente aus den deutschen Kernkraftwerken wurde von der Firma Gesellschaft für Nuklearbehälter, GNB, der Polluxbehälter entwickelt. Für den Transport muss er den Anforderungen der Rechtsvorschriften über den Transport gefährlicher Güter genügen. Für die Zwischen- und Endlagerung muss er die Forderungen der nach dem Atomgesetz genehmigungspflichtigen Anlagen erfüllen.
The transportation, interim storage and final disposal of nuclar material is a significant subject worldwide. The Pollux container was designed by the firm Gesellschaft für Nuklearbehälter, GNB, to accomodate the German concept of direct final disposal of spent fuel elements from German nuclear power stations. For the transportation task, the container must meet the requirements specified in the regulations for the safe transport of radioactive material. For the task of interim storage and final disposal, the requirements specified for nuclear facilities subject to approval under the German atomic energy act apply.
Verhüllter Reichstag
(1995)
Der Reichstag ist, neben dem Brandenburger Tor, eines der Symbole der deutschen Einheit. Dieser geschichtsbedeutende Bau wird nun bald wieder seine eigentliche Funktion als deutsches Parlament übernehmen. Die Aktionskünstler Christo und Jeanne-Claude sind durch viele international beachtete und weltweit ausgeführte Aktionen berühmt geworden. Beide Künstler bemühen sich seit mehr als 20 Jahren darum, diesem Gebäude durch eine Verhüllung seine hohe Beachtung zurückzugeben. Das von Christo und Jeanne-Claude erwählte Polypropylengewebe mit einseitiger Aluminiumbedampfung wird mit 100.000 Quadratmetern den Reichstag einhüllen und ihm, selbst bei bedecktem Himmel, eine faszinierende Ausstrahlung geben. Der verhüllte Reichstag wird mit seinem veränderten Aussehen nicht nur den Kunstinteressierten nach Berlin locken. Die zuständigen Politiker haben nach langer und kontroverser Debatte diesem wohl einmaligen Projekt zugestimmt. Die Durchführung im Sommer 1995 bringt aufgrund der Dimension und der Komplexität des Vorhabens einige bau- und materialtechnische Fragestellungen mit sich. Die BAM wurde beauftragt, hierfür ein Gutachten zu erstellen. Die Würde des Gebäudes und die sicherlich großen Zuschauermengen gestatten keine Experimente mit ungewissem Ausgang. Das Gutachten soll gewährleisten, dass seitens des Materials die sicherheitstechnischen und materialtechnologischen Voraussetzungen erfüllt sind.
Wrapped Reichstag
(1995)
Located next to the Brandenburg Gate, the Reichstag is one of the symbols of German unity. This historically important structure will soon take over its actual function as German parliament. Action artists Christo and Jeanne-Claude have achieved international fame for the many remarkable artistic events they have staged throughout the world. For more than 20 years, these two artists have been attempting to give back this building its noteworthy character by wrapping it. The polypropylene fabric selected by Christo and Jeanne-Claude with one-sided aluminisation will wrap the Reichstag with 100.000 square meters of material and give the building a fascinating aura even under overcast skies. With its changed appearance, the covered Reichstag will not only attract people interested in the arts to Berlin. The politicians in charge have approved this probably unique project following a series of lengthy and controversial debates. Due to the extent and complexity of the project, its execution in the summer of 1995 raises a number of questions regarding construction and material technology. The Federal Institute for Materials Research and Testing, BAM, was commissioned to write up an expert opinion for this project. The dignity of the building and the large numbers of spectators expected do not leave room for experiments with uncertain results. The expert opinion shall assure that the safety requirements and the requirements placed on material technology are met by the material being used.
The sintering behaviour of one microcrystalline and several nanocrystalline TiN powders was investigated by means of a gas pressure furnace with an integrated dilatometer. The investigated nanocrystalline powders strongly differ in the sintering activity. It can be concluded from the experiments, that small grain size, narrow grain size distribution and a low oxygen content are the most important prerequisites for high sintering activity of the nanocrystalline TiN powders.
The extraordinary sintering activity of the best TiN powder makes it possible to produce a dense (< 2 % porosity), pure (no sintering aids) and nanostructured (mean diameter of crystals about 100 nm) TiN bodies.
Polarized fluorescence spectroscopy is used to investigate the photophysical behavior of poly(p-phenylphenylenevinylene) (PPPV) in polystyrene matrix in comparison with oligomeric model compounds. For this purpose PPPV is modeled by a chain consisting of a distribution of independent oligomeric segments. Excitation energy transfer (EET) between the segments depends on the wavelength of excitation, not only for transfer along an isolated polymer chain, but also for intermolecular transfer at high concentration of PPPV. The spatial range of EET, as indicated by fluorescence depolarization, is reduced for excitation at the long wavelength edge of the absorption spectrum ("red-edge-effect").
Stationary polarized fluorescence spectra of poly(1,4-phenylene-1-phenylvinylene), poly(1,4-phenylene-1,2-diphenylvinylene) and poly[1,4-phenylene-1,2-bis(4-phenoxyphenyl)vinylene] in tetrahydrofuran solution and in polystyrene films were recorded at room temperature. In these matrices, different behaviour is found concerning the Stokes shift, the degree of polarization and the quantum yield; it is interpreted as a viscosity induced effect. The commonly accepted model of a conjugated polymer chain to consist of independent segments of various length should not be applied to the poly(phenylene-arylvinylene)s studied in this work.
A method is developed to determine orientational order parameters <P2> and <P4> of films by steady state fluorescence polarization in a spectrometer with 90° angle between excitation and emission beam. This is the geometry usually found in commercial fluorescence spectrometers. The method includes the determination of the fundamental molecular anisotropy rM of the fluorescent chromophore (doped or intrinsic) in stretched and unstretched films and the determination of instrumental correction coefficients from an isotropic film. As an example, the method is applied to orientation analysis of polyethylene and polystyrene films doped with fluorescent molecules of repetitive styrene units. It is concluded that in uniaxially stretched polyethylene-films orientation of these molecules is dominated by their molecular shape; in polystyrene films orientation is influenced by additional interactions.
Extended drop tests of DCI casks with artificial flaws demonstrating the existing safety margins
(1995)
Safety measures
(1995)
Pollutant Transport
(1995)
Energy Dissipation of the Fibre-Matrix Debonding Process Investigated with the Indentation Technique
(1995)
An advanced equipment for single-fibre pull-out test designed to monitor the fracture process
(1995)
For the assessment of the barrier function of the geosphere around a nuclear waste repository information about the nature of the accessible rock pore space and internal surfaces is needed. Intact samples of various types of fresh and altered crystalline rocks have been studied by means of mercury intrusion porosimetry and gas adsorption methods using various adsorbates. Furthermore, fluorescence microscopy and scanning electron microscopy was applied and the results were compared with those of impregnation with carbon-l4-polymethylmethacrylate (PMMA). Additional structural information was derived from hydraulic conductivity determinations using helium gas.
The investigations were focussed on the reliability of these measurements of intact core samples, the influence of rock composition, structure and geological evolution on the microstructure of the matrices and the consequences regarding the retardation properties of the bedrock.
Zwischen Chemie, Wirtschaft und Politik - Aus den Aufgaben einer Chemisch-Technischen Bundesanstalt
(1995)
In situ optical second-harmonic generation (SHG) on centrosymmetric crystalline semiconductor electrodes opens up a new field of in situ investigations of hurried solid state interfaces and metal front contacts relevant to electronic and photovoltaic devices, which are rarely accessible by other methods. Photoelectrochemical nanosecond- and femtosecond-pulse laser investigations of silicon (111) electrodes show that in situ SHG is feasible in such complex interfacial systems. In a p-p polarization configuration, the azimuthal dependence of the SHG from oxide-covered and bare n-Si (111) electrodes, with and without Ni contact deposits, have been studied. Etching and regrowth of silicon oxides as well as burried interfacial electric field distributions were monitored. In situ SHG is shown to be extremely sensitive to trapped interfacial charge, crystal misorientations and surface step arrays. An advantage of femtosecond-pulses is the fact that illumination fluences that are well below the damage threshold, but still with sufficient power density, can be applied. (Author)
Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a useful new technique for the determination of the chemical structure and the molar mass distribution of poly(ethylene oxides). Investigating different alkyloxy and aryloxy polyethylene oxides, we have shown that MALDI-MS gives accurate molar masses, provided that the oligomer masses are above 400 g/mol. Below 400 g/mol, mass discrimination effects have to be taken into account. A perfect fit of MALDI-MS with data, determined independently by supercritical fluid chromatography and high performance liquid chromatography, was obtained.
Gaseous oxygen impacts may occur in high-pressure oxygen systems whenever oxygen equipment is pressurized too fast. This is one of the main causes of fires in such systems. Therefore, equipment for high-pressure oxygen that contains nonmetallic sealing materials should be tested for burn-out safety. This is required by numerous international standards such as ISO, CEN or national standards as DIN in Germany. Because of new technical developments in industrial uses of oxygen, higher operating pressures up to 500 bar are becoming more and more frequent. With regard to this need, a new 500 bar gaseous oxygen impact tester has been designed and built at the Federal Institute for Materials Research and Testing (BAM) in Berlin (Germany). This paper describes all elements of this test system. The most important element of this BAM test apparatus is a new hydraulically operated quick opening valve that meets all international standards. First experiences on performance and maintenance of the new test apparatus are given.
Zulassung von Schutzlagen
(1995)