[en] A model has been produced to describe irradiation damage in high nickel submerged arc welds (1.6% Ni, 1.5% Mn, 0.5% Mo). It is fitted to a database of hardness change results obtained for 12 such welds with copper contents from about 0.02 to about 0.6% irradiated in materials test reactors. Irradiation dose rates ranged from about 6x10^-9 dpa/s down to about 1x10^-10 dpa/s. In addition to the hardness change data, Charpy shift data were also available. For some specimens irradiation induced changes in microstructure have been characterised using small angle neutron scattering (SANS) and energy compensated position sensitive atom probe (ECoPoSAP) techniques. The model was empirically fitted to the data, but available physical understanding and the evidence from the microstructural studies were used to guide selection of the equations fitted. Physical understanding and microstructural evidence were also used to help choose between alternative models with similar statistical goodness of fit. The model has two components. First, 'matrix' damage, which is insensitive to copper content and irradiation dose rate, and which appears to increase with phosphorus and sulphur. Second, 'precipitation damage', which increases with copper and manganese content, and reduces with increasing silicon. Precipitation damage also increases with reducing irradiation dose. The ECoPoSAP data show that the precipitates are composed of primarily of Ni, Mn, Cu and Si, with a substantial amount of iron entrained within them. In the low copper welds the same instrument shows significant compositional fluctuations in these elements, but no visible clusters. The Charpy data have been used to develop an empirical correlation between transition shift and hardness change. This is linear up to about 250 deg. C shift

[en] We have demonstrated that sintered LiF spatial filters may be used in a 10^-6-torr vacuum environment as laser-initiated plasma shutters for retropulse isolation in the Antares high-energy laser fusion system. In our experiments, a 1.1-ns pulsed CO₂ laser, at a 10-μm wavelength and an energy of up to 3.0 J, was used for plasma initiation; a chopped probe laser tuned to a 9l6-μm wavelength was used in determining the blocking time of the plasma. We measured the 10.6- and 9.6-μm beam transmissions as a function of fluence on the aperture edge. For an 800-μm-diam aperture and a 1.2-mm-diam Gaussian beam determined at the 1/e² intensity points, we observed blocking times in excess of 1.0 μs

[en] Through award of ten contracts under the solicitation, DOE is continuing efforts to develop innovative technologies for decontamination and recycling or reusing of process equipment, scrap metal, and concrete. These ten technologies are describe briefly in this report. There is great economic incentive for recycling or reusing materials generated during D ampersand D of DOE's facilities. If successfully developed, these superior technologies will enable DOE to clean its facilities by 2019. These technologies will also generate a reusable or recyclable product, while achieving D ampersand D in less time at lower cost with reduced health and safety risks to the workers, the public and the environment

[en] One of the US Department of Energy's (DOE) major goals is to clean up its contaminated facilities by the year 2019. The primary contaminants at DOE sites are radioactive materials, organic compounds, and heavy metals. The most common radioactive materials are isotopes of uranium and plutonium, although lesser quantities of thorium, technetium, neptunium and americium are also found. Organic contamination includes lubricating oils, cutting fluids, kerosene, solvents, and polychlorinated biphenyls. Heavy metal contaminants include mercury, arsenic, chromium, lead, and cadmium. The Office of Technology Development (OTD) within DOE's Office of Environmental Restoration and Waste Management is charged with developing innovative technologies to clean up DOE facilities. The DOE's Morgantown Energy Technology Center is assisting the OTD by procuring and managing research projects to develop the innovative technologies. These innovative technologies promise to be faster, better, cheaper and safer than the current suite of environmental remediation technologies. With sufficient decontamination, much of the materials from the DOE facilities could be released as scrap to the commercial sector or reused within the DOE complex. The potential for recycling or reusing materials, including strategic metals such as nickel, is enormous if the materials are properly decontaminated. This paper will discuss innovative technologies to decontaminate and recycle or reuse scrap metal, concrete, and process equipment

[en] The relation between micro-electric discharge machining and surface topography is examined on stainless steel surfaces. The surfaces are measured using a scanning laser confocal microscope and the measurements are characterized with conventional parameters and parameters from multi-scale areal fractal analysis. The measurements from the confocal microscope are sufficiently precise and the surfaces are sufficiently different so that they are clearly discriminated at scales as small as 0.008 μm². Surface features less than 500 nm laterally are clearly discernible on the surfaces. Using linear regression analyses texture characterization parameters derived from the multi-scale analysis were found to correlate more strongly with the discharge pulse energies used to machine the surfaces (R² > 0.97) than to the conventional parameters (R² < 0.93). In addition the multi-scale analyses indicate at what scales the discrimination and strong correlations are possible. (paper)

[en] A novel method of decreasing ohmic losses and increasing Q-value in metallic resonators at high frequencies is presented. The method overcomes the skin-depth limitation of rf current flow cross section. The method uses layers of conductive foil of thickness less than a skin depth and capacitive gaps between layers. The capacitive gaps can substantially equalize the rf current flowing in each layer, resulting in a total cross-sectional dimension for rf current flow many times larger than a skin depth. Analytic theory and finite-element simulations indicate that, for a variety of structures, the Q-value enhancement over a single thick conductor approaches the ratio of total conductor thickness to skin depth if the total number of layers is greater than one-third the square of the ratio of total conductor thickness to skin depth. The layer number requirement is due to counter-currents in each foil layer caused by the surrounding rf magnetic fields. We call structures that exhibit this type of Q-enhancement “meta-metallic.” In addition, end effects due to rf magnetic fields wrapping around the ends of the foils can substantially reduce the Q-value for some classes of structures. Foil structures with Q-values that are substantially influenced by such end effects are discussed as are five classes of structures that are not. We focus particularly on 400 MHz, which is the resonant frequency of protons at 9.4 T. Simulations at 400 MHz are shown with comparison to measurements on fabricated structures. The methods and geometries described here are general for magnetic resonance and can be used at frequencies much higher than 400 MHz.

[en] Predictions for the corrosion behaviour of Zircaloy cladding are based on empirical models. This results in significant uncertainties for forecasts beyond existing data e.g. for high burn-up, or when there has been a change in operating conditions. To allow for a more accurate prediction of corrosion behaviour a better understanding of the mechanisms involved is required. A program has been initiated with the aim of developing a detailed mechanistic understanding of out-of-pile Zircaloy corrosion behaviour. This paper reports the results of isothermal exposures of Zircaloy-4 to PWR water at 350 Celsius degrees. A variety of analytical techniques have been employed to analyse the corroded specimens, including scanning and transmission electron microscopy, atom probe tomography, micro-beam synchrotron X-ray diffraction and electron energy loss spectroscopy. When the results of these techniques are compared, it becomes evident that the periodic transition from slow to fast oxidation rates results from the accumulation of stress relief processes in the metal (particularly plastic deformation, but also oxygen and hydrogen dissolution); at the metal-oxide interface (decomposition of the flat interface into undulations); and in the oxide (cracking). These reduce the in-plane compressive stresses near the metal-oxide interface but ultimately balance them with in-plane tensile stresses which encourage through-thickness cracking, and the percolation of the environment to the metal-oxide interface. This is noticed only if allowance is made for out-of-plane stresses in the thin oxide. (authors)