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This article is about the Chopping effect observed at cathodic arc initiation. It is argued that current chopping at the rising edge is similar to the current chopping effect that is well-known for the arc current approaching current-zero.

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This is the third quarterly report on oxygen Transport Ceramic Membranes. In the following, the report describes the progress made by our university partners in Tasks 1 through 6, experimental apparatus that was designed and built for various tasks of this project, thermodynamic calculations, where applicable and work planned for the future. (Task 1) Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. (Task 2) Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. (Task 3) Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. (Task 4) Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. (Task 5) Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. (Task 6) Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

A fundamental part of geophysics is to make inferences about the interior of the earth on the basis of data collected at or near the surface of the earth. In almost all cases these measured data are only indirectly related to the properties of the earth that are of interest, so an inverse problem must be solved in order to obtain estimates of the physical properties within the earth. In February of 1999 the U.S. Department of Energy sponsored a workshop that was intended to examine the methods currently being used to solve geophysical inverse problems and to consider what new approaches should be explored in the future. The interdisciplinary area between inverse problems in geophysics and optimization methods in mathematics was specifically targeted as one where an interchange of ideas was likely to be fruitful. Thus about half of the participants were actively involved in solving geophysical inverse problems and about half were actively involved in research on general optimization methods. This report presents some of the topics that were explored at the workshop and the conclusions that were reached. In general, the objective of a geophysical inverse problem is to find an earth model, described by a set …

The projects outlined in detail on the attached project reports are a summary of the many projects implemented in the Pataha Creek Model Watershed since it was selected as a model in 1993. Up until last year, demonstration sites using riparian fencing, off site watering facilities, tree and shrub plantings and upland conservation practices were used for information and education and was the main focus of the implementation phase of the watershed plan. These practices are the main focus of the watershed plan to reduce the majority of the sediment entering the stream. However, the watershed stream evaluation team used in the watershed analysis determined that there were problems along the Pataha Creek that needed to be addressed that would add further protection to the banks and therefore a further reduction of sedimentation into the stream. 1999 was a year where a focused effort was made to work on the upland conservation practices to reduce the sedimentation into Pataha Creek. Over 95% of the sediment entering the stream can be tied directly to the upland and riparian areas of the watershed. In stream work was not addressed this year because of the costs associated with these projects and the low …

The initial design criteria of the MSW to ethanol facility have been completed along with preliminary site identification and layouts for the processing facility. These items are the first step in evaluating the feasibility of this co-located facility. Pilot facility design and modification are underway for the production and dewatering of the lignin fuel. Major process equipment identification has been completed and several key unit operations will be accomplished on rental equipment. Equipment not available for rental or at TVA has been ordered and facility modification and shakedown will begin in October. The study of the interface and resulting impacts on the TVA Colbert facility are underway. The TVA Colbert fossil plant is fully capable of providing a reliable steam supply for the proposed Masada waste processing facility. The preferred supply location in the Colbert steam cycle has been identified as have possible steam pipeline routes to the Colbert boundary. Additional analysis is underway to fully predict the impact of the steam supply on Colbert plant performance and to select a final steam pipeline route.

We describe the design, construction and performance of an instrument designed to monitor compliance with future arms control treaties. By monitoring changes in the gamma-ray spectrum emitted by a stored nuclear weapon, our device is able to sense perturbations in the contents of a weapon storage container that would indicate treaty non-compliance. Our instrument (dubbed the Radiation Continuity Checker or RCC) is designed to detect significant perturbations in the gamma-ray spectra (indicative of tampering) while storing no classified information about the weapon, and having a negligible ''false alarm rate''. In this paper we describe the technical details of two prototype instruments and describe the strategies we have adopted to perform signal processing in these instruments. Our first instrument prototype uses a scintillation spectrometer and a massive tungsten alloy collimator to reject the gamma-ray background. Our second prototype instrument makes use of an active collimation scheme employing a multiple detector Compton scatter approach to reject background radiation. The signal processing method we employ uses linear algorithms applied pulse by pulse. This eliminates the need for storage of pulse height spectra, which are in many cases classified.

The information needs of managers with respect to avian species at the SRS are identified. The process by which information is integrated into decision making are discussed. Numerous studies of upland bird species at SRS were conducted as part of the DOE Biodiversity Program. This information is being incorporated into biological assessments and plan through modeling and geographic information systems.

A great advantage of some neutron sources, such as accelerator-produced sources, is that they can be tuned to produce different spectra. Unfortunately, optimization studies are often time-consuming and difficult, as they require a lengthy Monte Carlo simulation for each source. When multiple characteristics, such as energy, angle, and spatial distribution of a neutron beam are allowed to vary, an overwhelming number of simulations may be required. Many optimization studies, therefore, suffer from a small number of datapoints, restrictive treatment conditions, or poor statistics. By scoring pertinent information from every particle tally in a Monte Carlo simulation, then applying appropriate source variable weight factors in a post-processing algorithm, a single simulation can be used to model any number of multiple sources. Through this method, the response to a new source can be modeled in minutes or seconds, rather than hours or days, allowing for the analysis of truly variable source conditions of much greater resolution than is normally possible when a new simulation must be run for each datapoint in a study. This method has been benchmarked and used to recreate optimization studies in a small fraction of the time spent in the original studies.

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Under Task 24, the RAE Team provided Quality Assurance support to the Special Recovery Line (SRL) and the Advanced Recovery and Integrated Extraction System (ARIES) projects of NMT-6. Support was provided through ESH-14. Monthly reports of work performed under this task were provided to NMT-6 and ESH-14. Copies of these reports are in RAE's project files. The procedures and assessment reports required by the task are on file only at NMT-6 because of the sensitive nature of the information. In March 1999, our subcontractor, General Physics, informed us that the two individuals working on the task were resigning effective April 2, 1999. RAE notified Gary Cort, ESH-14 technical representative for the task, and offered to replace the two individuals so that we could complete our obligations under the task (e-mail attached). No reply was ever received from Mr. Cert. We then reiterated our concern and offer of replacement with Mr. Cort's deputy, Spencer Hill (e-mail attached). No reply was received from Mr. Hill either. We subsequently learned the two General Physics employees were hired by another contractor and that the remaining work under the task was given to that contractor. We assumed our obligations under the task were completed at …

The purpose of this task was to support ESH-3 in providing Airborne Release Fraction and Respirable Fraction training to safety analysts at LANL who perform accident analysis, hazard analysis, safety analysis, and/or risk assessments at nuclear facilities. The task included preparation of materials for and the conduct of two 3-day training courses covering the following topics: safety analysis process; calculation model; aerosol physic concepts for safety analysis; and overview of empirically derived airborne release fractions and respirable fractions.

Under this task, RAE personnel were on call to accompany members of the Concerned Citizens for Nuclear Safety (CCNS) if and when they exercised the option to borrow radiac instruments from the Laboratory and survey areas they thought might be contaminated by the Lab. Five members of the RAE team were given refresher training on the latest Lab owned instruments and on Lab procedures for using them and reporting results. On one occasion, a RAE team member accompanied LANL personnel when they did a survey of a house trailer which the owner claimed may have been contaminated. No contamination was found at the site. No requests were received to accompany CCNS members. The original task completion date of September 30, 1998 was extended to June 21, 1999. No requests were received to accompany CCNS members during this timeframe either. The task was terminated as it was determined there was no longer a need.

This quarterly technical progress report will summarize work accomplished for the Program through the second quarter July--September 2000 in the following task areas: Task 1-Oxygen Enhanced Combustion, Task 2-Oxygen Transport Membranes and Task 4-Program Management. The program is proceeding in accordance with the objectives for the first year. OTM tube characterization is well underway, the design and assembly of the high pressure permeation test facility is complete and the facility will be in full operation during the next quarter. Combustion testing has been initiated at both the University of Arizona and Praxair. Testing at the University of Arizona has experienced some delays; steps have been take to get the test work back on schedule. Completion of the first phase of the testing is expected in next quarter. Combustion modeling has been started at both REI and Praxair, preliminary results are expected in the next quarter.

For many scientific calculations, Monte Carlo is the only practical method available. Unfortunately, standard Monte Carlo methods converge slowly as the square root of the computer time. We have shown, both numerically and theoretically, that the convergence rate can be increased dramatically if the Monte Carlo algorithm is allowed to adapt based on what it has learned from previous samples. As the learning continues, computational efficiency increases, often geometrically fast. The particle transport work achieved geometric convergence for a two-region problem as well as for problems with rapidly changing nuclear data. The statistics work provided theoretical proof of geometic convergence for continuous transport problems and promising initial results for airborne migration of particles. The statistical physics work applied adaptive methods to a variety of physical problems including the three-dimensional Ising glass, quantum scattering, and eigenvalue problems.

A comprehensive investigation of natural and manmade silicate glasses, and nuclear melt glass was undertaken in order to derive an estimate of glass reactive surface area. Reactive surface area is needed to model release rates of radionuclides from nuclear melt glass in the subsurface. Because of the limited availability of nuclear melt glasses, natural volcanic glass samples were collected which had similar textures and compositions as those of melt glass. A flow-through reactor was used to measure the reactive surface area of the analog glasses in the presence of simplified NTS site ground waters. A measure of the physical surface area of these glasses was obtained using the BET gas-adsorption method. The studies on analog glasses were supplemented by measurement of the surface areas of pieces of actual melt glass using the BET method. The variability of the results reflect the sample preparation and measurement techniques used, as well as textural heterogeneity inherent to these samples. Based on measurements of analog and actual samples, it is recommended that the hydraulic source term calculations employ a range of 0.001 to 0.01 m{sup 2}/g for the reactive surface area of nuclear melt glass.

As part of Task 1 in the Advanced Technologies for Stripper Gas Well Enhancement, Schlumberger--Holditch Reservoir Technologies (H-RT) has partnered with two Appalachian Basin producers, Great Lakes Energy (formerly Range Resources) and Belden and Blake Corporation, to develop methodologies for the identification and enhancement of stripper wells with economic upside potential. These industry partners have provided data for over 700 wells in northwestern Pennsylvania. Phase 1 goals of this project are to develop and validate methodologies that can quickly and cost-effectively identify wells with enhancement potential. We are currently in the final stages of developing and testing our new Access/Excel based software and processing this well data to generate a list of potential candidate wells that can be used in Phase 2 to validate these methodologies.

As part of Phase 1 in the Advanced Technologies for Stripper Gas Well Enhancement, Schlumberger--Holditch Reservoir Technologies (H-RT) has partnered with two Appalachian Basin producers, Great Lakes Energy (formerly Range Resources) and Belden & Blake Corporation, to develop methodologies for the identification and enhancement of stripper wells with economic upside potential. These industry partners have provided data for over 700 wells in northwestern Pennsylvania. Phase 1 goals of this project are to develop and validate methodologies that can quickly and cost-effectively identify wells with enhancement potential. We are currently processing the production and well data and developing our new Access/Excel based software that incorporates our identification methodologies. Upon completion we will generate a list of potential candidate wells that can be used in Phase 2 to validate these methodologies.

Past nuclear activities at SRS have resulted in low level contamination in various wetlands. The wetlands and reservoirs serve a major wintering ground for migratory waterfowl. American coots have the highest level of cesium accumulation among the birds. The concentration has decreased exponentially with a four year half-life. The current levels pose no threat to human consumption.

Abstract: We have investigated the performance of dual metal oxide electrode mixed potential sensors in an engine-out, dynamometer environment. Sensors were fabricated by sputtering thin films of LaMnO{sub 3} and Tb-doped YSZ onto YSZ electrolyte. Au gauze held onto the metal oxide thin films with Au ink was used for current collection. The exhaust gas from a 4.8L, V8 engine operated in open loop, steady-state mode around stoichiometry at 1500 RPM and 50 Nm. The sensor showed a stable EMF response (with no hysteresis) to varying concentrations of total exhaust gas HC content. The sensor response was measured at 620 and 670 C and shows temperature behavior characteristic of mixed potential-type sensors. The results of these engine-dynamometer tests are encouraging; however, the limitations associated with Au current collection present the biggest impediment to automotive use.

The wood stork is a recently classified federally endangered species. The species forages throughout the facility. The facility impact was mitigated by replacing the affected area with artificially created impoundment. Studies conducted in conjunction with the mitigation have assisted with the recovery effort for this species.

Long-term bio-monitoring of avian communities have been initiated, but they often lack a management component. Integration of the managers needs at an early stage is suggested as a means to increase the use of the data. Variation in community structure is important in understanding impacts. In addition, reference site must be carefully selected.