An impedance camera [Henderson and Webster, 1978; Dines and Lytle, 1981]--or what is now more commonly called electrical impedance tomography--attempts to image the electrical impedance (or just the conductivity) distribution inside a body using electrical measurements on its boundary. The method has been used successfully in both biomedical [Brown, 1983; Barber and Brown, 1986; J. C. Newell, D. G. Gisser, and D. Isaacson, 1988; Webster, 1990] and geophysical applications [Wexler, Fry, and Neurnan, 1985; Daily, Lin, and Buscheck, 1987], but the analysis of optimal reconstruction algorithms is still progressing [Murai and Kagawa, 1985; Wexler, Fry, and Neurnan, 1985; Kohn and Vogelius, 1987; Yorkey and Webster, 1987; Yorkey, Webster, and Tompkins, 1987; Berryman and Kohn, 1990; Kohn and McKenney, 1990; Santosa and Vogelius, 1990; Yorkey, 1990]. The most common application is monitoring the influx or efflux of a highly conducting fluid (such as brine in a porous rock or blood in the human body) through the volume being imaged. For biomedical applications, this met hod does not have the resolution of radiological methods, but it is comparatively safe and inexpensive and therefore provides a valuable alternative when continuous monitoring of a patient or process is desired. The following discussion is intended …

The spinel LiMn{sub 2}O{sub 4} has been extensively studied as a positive electrode active material in lithium rechargeable batteries. Partial substitution of Mn by another metal has also been the subject of recent study in an effort to improve the cycling performance. In general, the literature has shown that Mn substitution results in improved cycling stability at the expense of capacity (1,2). Resistance to the formation of tetragonal phase upon lithiation of the starting spinel (via a higher nominal Mn oxidation state in the substituted spinel) has been suggested as a mechanism for the improved performance. The degree of substitution is an important factor to optimize in order to minimize capacity loss and costs. The spectroscopic investigations on LiMn{sub 2}O{sub 4} described in the previous paper (LixMn2O4) confirmed that the cooperative Jahn-Teller effect (CJTE) from the [Mn{sup 3+}O{sub 6}] octahedra is the mechanism for the cubic to tetragonal phase transformation. The driving force for the CJTE is based upon the electronic structure, therefore changes in electronic structure should lead to changes in the phase behavior. The fact that the LiMn{sub 1.5}Ni{sub 0.5}O{sub 4} does not form tetragonal phase upon discharging (FUJI3, MUCK?), unlike the 100% Mn{sup 4+} spinel Li{sub 4}Mn{sub …

One of the more difficult analyses in the transplutonium field is the determination of americium at trace levels in a complex matrix such as a process dissolver solution. Because of these conditions a highly selective separation must precede the measurement of americium. The separation technique should be mechanically simple to permit remote operation with master-slave manipulators. For subsequent americium measurement by the mass spectroscopic isotopic-dilution technique, plutonium and curium interferences must also have been removed.

Visibility and radioactivity control in the fuel component storage and disassembly basins at the Savannah River Plant are maintained with a newly developed purification system. Experimental work was performed to develop the application of sand filters to operate at high flow rates with an effluent turbidity below 0.1 JTU squared. Filtration efficiency of SRP sand filters is dependent on the characteristics of the solids in the feed water and the degree to which filterability can be improved by addition of coagulant aids. It is independent of flow up to flow rates of 15 gpm/square feet (higher flow rates have not been tested). Effluent turbidity remains below 0.1 JTU with no indication of breakthrough. Total water throughput is dependent on the amount of solids removed and is independent of flow rate and concentration of solids.

Immobilization of high-level radioactive waste (HLW) in borosilicate glass is acknowledged world-wide as an acceptable method for preparing HLW for geologic disposal. A waste acceptance process is underway in the United States that will provide specifications and procedures for waste producers well in advance of the availability of a federal repository. Extensive experimental data and rigorous quality assurance and control for plant operation are expected to provide convincing evidence that borosilicate glass waste forms produced in the vitrification plants meet the specifications and can be disposed of safely in a geologic repository.

This paper describes a mobile analyzer for sulfur hexafluoride, an atmospheric tracer. A commercial instrument is used on-board a moving vehicle to measure tracer concentrations in the parts per trillion (ppt) range. This instrument provides rapid, in-the-field data at minimum cost.

This paper discusses some of the metal hydride and intermetallic compounds which readily absorb the hydrogen gas by a simple contact to form metal hydrides. Metal hydrides have several important properties for the hydrogen isotope separation.

There were 90 papers presented at the Conference in the category of Technology and Power Plants accounting for about 25% of the total number of contributions. As was the case at the previous meeting, a large number of papers dealt with the ITER-Engineering Design Activity (EDA) and ITER technology R&D. In the author's opinion, the rapid progress made during the ITER EDA extension on the completion of the new ITER-FEAT design and its physics and technology R&D validation stands out as the highlight of the meeting. Steady progress is being made on several other technology fronts as well. The results point towards emerging research trends in the following areas: steady-state operation with advanced performance and the increasingly important role of enabling technologies in achieving this goal, advanced, high-performance, environmentally attractive materials for the fusion energy goal, reactor and near-term applications studies that exploit advances both in the physics and technology fronts for lower cost of electricity and improved safety and environmental features, and socioeconomic studies that are helping to promote the attractive features of fusion and its public acceptance. The remaining sections of this paper are organized along the lines of these major themes; namely, ITER EDA Design, ITER Technology …

Tensile creep studies were carried out to evaluate the creep performance of AS800 silicon nitride samples extracted from the surface and bulk regions of as-processed billets at 1350 C in air. The objective of this study was to understand the creep properties of the silicon nitride in the as-processed surface region and determine if they are comparable to those obtained from the bulk region. The results indicated that samples from the as-processed surface region exhibited higher creep rates and shorter lifetimes as compared with those obtained from the bulk region. The poor creep performance of material from the as-processed surface region was due to the higher content of glassy phase enriched with oxygen and sintering additive elements.