[en] This paper discussed the principles and techniques of Eddy current testing as the best non-destructive testing methods of testing in heat exchangers. (ELC). 6 figs

[en] At the beginning of this quarter, Air Products, Chevron, Norsk Hydro, and McDermott met to kick off the Process Design task. A process design strategy that includes scope, design basis, and plant location and scale was developed for both gas-to-liquids (GTL) and H(sub 2) applications. For GTL, the strategy is based on the initial design of an ITM Syngas plant for a Gulf Coast land-based GTL facility, carried out by Chevron and Air Products. This design will be adapted to the Alaskan North Slope GTL application by McDermott and Chevron, with input from the University of Alaska and ARCO. McDermott Technology will adapt the land-based GTL to a Gulf Coast offshore GTL application, and Norsk Hydro with McDermott will adapt the offshore GTL design to other offshore locations as needed

[en] A critical component of the DOE decontamination and decommissioning effort is the characterization of radioactively contaminated equipment and structures. Gamma-ray spectroscopy and imaging with germanium (Ge) based detectors are powerful techniques that allow for the quick and accurate in-situ identification, spatial mapping, and quantification of radioactive contaminants. However, the image resolution obtained with a Ge detector can be limited by the accuracy to which the gamma-ray interaction events are spatially detected within the detector itself. Our primary objective is to develop the technologies necessary to produce Ge gamma-ray detectors with enhanced accuracy in locating gamma-ray interaction events thereby resulting in improved image resolution. Our approach is to locate the gamma ray interaction events within the detector in all three dimensions rather than just two. Additionally, we will base the detectors on known and tested LBNL fabrication technologies and utilize the simplest possible detector geometries and signal-readout electrode structures in order to reduce the system complexity and difficulties in fabrication. The technologies developed as a result of this research will form the basis for the design and construction of future high-performance gamma-ray imaging systems. These instruments will greatly facilitate DOE's radioactive materials characterization process

[en] Critical to the DOE effort to deactivate and decommission the weapons complex facilities is the characterization of contaminated equipment and building structures. This characterization includes the isotopic identification of radioactive contaminants and the spatial mapping of these deposits. The penetrating nature of the gamma rays emitted by the radioactive contaminants provides a means to accomplish this task in a passive, non-destructive and non-intrusive manner. Through conventional gamma-ray spectroscopy, the radioactive isotopes in the contaminants can be identified by their characteristic gamma-ray signatures and the amount of each isotope by the intensity of the signature emission. With the addition of gamma-ray imaging, the spatial distributions of the isotopes can simultaneously be obtained. The ability to image radioactive contaminants can reduce waste as well as help ensure the adequate protection of workers and the environment. For example, if equipment and building materials have been subjected to radionuclide contamination, the entire structure must be treated as radioactive waste during demolition. However, only partial removal may be necessary if the contamination can be accurately located and identified. Hand-held survey instrumentation operated in the near vicinity of the contaminated objects is a common method to accomplish this task. This method necessitates long data acquisition times, direct close access, and considerable worker exposure, as well as leads to imprecise information. In contrast, imaging devices operated at a distance from the contaminated objects can accurately acquire the spatially dependent gamma-ray emission information in a single measurement. Consequently, the devices can more efficiently discriminate between contaminated and non-contaminated areas of heterogeneous objects while at the same time reducing worker exposure

[en] Critical experiments concerning OTTO loading are described. In the KAHTER facility an OTTO loading has been simulated, therefore the original KAHTER assembly was reconstructed. The determination of critical masses and reactivity worths of control rods and of additional absorber rods in the top reflector and in the upper cavity was of main interest for comparison with reactor following calculations. Besides this, reaction rates in different energy regions were measured in the upper part of the core, in the cavity and top reflector. (orig.)

[en] Gamma-ray spectroscopy is a valuable tool of science and technology. Many applications for this tool are in need of a detector technology capable of achieving excellent energy resolution and efficient detection while operating at room temperature. Detectors based on the material cadmium zinc telluride (CdZnTe) could potentially meet this need if certain material deficiencies are addressed. The coplanar-grid as well as other electron-only detection techniques are effective in overcoming some of the material problems of CdZnTe and, consequently, have led to efficient gamma-ray detectors with good energy resolution while operating at room temperature. At the present time, the performance of these detectors is mainly limited by the degree of uniformity in electron generation and transport. Despite recent progress in the growth of CdZnTe material, small variations in these properties remain a barrier to the widespread success of such detectors. Alpha-particle response characterization of Cd ZnTe crystals fabricated into simple planar detectors provides an effective tool to accurately study such variations. We have used a finely collimated alpha source to produce two-dimensional maps of detector response. For a number of crystals, a clear correlation has been observed between their alpha response maps and the distribution of tellurium inclusions inside the crystals. An analysis of the induced charge signals indicates that regions of enhanced electron trapping are associated with the inclusions, and that these regions extend beyond the physical size of the inclusions. Such regions introduce non-uniform electron trapping in the material that then degrades the spectroscopic performance of the material as a gamma-ray detector

[en] We show that two-dimensional Si/Ge nanostructures can be imaged with chemical sensitivity on the nanometer scale using a scanning tunneling microscope (STM). Using an atomic layer of Bi terminating the surface, we can distinguish between Si and Ge. The apparent height measured by the STM is ∼0.09 nm higher at areas consisting of Ge than on areas consisting of Si. This distinction between Si and Ge enabled us to fabricate and characterize two-dimensional Si/Ge nanostructures in a controlled way. Si/Ge nanostructures consisting of alternating Si and Ge rings having a width of 5-10 nm were grown around a 2D Si core island on a Si(111) substrate. The thickness of the Si and Ge rings is only one atomic layer (0.3 nm). Intermixing of Ge and Si is observed if the growth conditions are not chosen properly. The optimized growth conditions were obtained by lowering the temperature and decreasing the growth rate to prevent intermixing and nucleation of secondary islands. The present fabrication method is expected to be applied for nanostructured devices

No abstract available

[en] The design and construction of a hypersonic waterjet apparatus is described. Jet velocities from 0.5 to 5 km/s have been achieved using a high explosive charge. Images are obtained in situ on various target substrates using a high-speed framing camera. Experimental results are shown for the impact of high velocity waterjets on propellants and high explosive samples. By observing the impact of the waterjet at a wide range of velocities a safety threshold can be determined where no reaction takes place

[en] The coplanar-grid as well as other electron-only detection techniques are effective in overcoming some of the material problems of CdZnTe and, consequently, have led to efficient gamma-ray detectors with good energy resolution while operating at room temperature. The performance of these detectors is limited by the degree of uniformity in both electron generation and transport. Despite recent progress in the growth of CdZnTe material, small variations in these properties remain a barrier to the widespread success of such detectors. Alpha-particle response characterization of CdZnTe crystals fabricated into simple planar detectors is an effective tool to accurately study electron generation and transport. We have used a finely collimated alpha source to produce two-dimensional maps of detector response. A clear correlation has been observed between the distribution of precipitates near the entrance contact on some crystals and their alpha-response maps. Further studies are ongoing to determine the mechanism for the observed response variations and the reason for the correlation. This paper presents the results of these studies and their relationship to coplanar-grid gamma-ray detector performance