We are developing an advanced process for treatment of mixed wastes in molten salt media at temperatures of 700--1000{degrees}C. Waste destruction has been demonstrated in a single stage oxidation process, with destruction efficiencies above 99.9999% for many waste categories. The molten salt provides a heat transfer medium, prevents thermal surges, and functions as an in situ scrubber to transform the acid-gas forming components of the waste into neutral salts and immobilizes potentially fugitive materials by a combination of particle wetting, encapsulation and chemical dissolution and solvation. Because the offgas is collected and assayed before release, and wastes containing toxic and radioactive materials are treated while immobilized in a condensed phase, the process avoids the problems sometimes associated with incineration processes. We are studying a potentially improved modification of this process, which treats oxidizable wastes in two stages: pyrolysis followed by catalyzed molten salt oxidation of the pyrolysis gases at ca. 700{degrees}C. 15 refs., 5 figs., 1 tab.

A well-stirred reactor experiment and chemical kinetic modeling effort were performed in order to study the effect of ethylene oxidation on the conversion of nitric oxide (NO) to nitrogen dioxide (NO{sub 2}). Parameters examined in this study were temperature (1003--1260K) and input hydrocarbon concentration (220--3270 ppmv wet). The stirred reactor residence time was maintained at {approximately}2 milliseconds. Kinetic calculations indicated the NO to NO{sub 2} conversion proceeded through the ``HO{sub 2} mechanism``, NO + HO{sub 2} {yields} NO{sub 2} + OH, and the majority of the conversion occurred within the well-stirred reactor. The chemical kinetic mechanism used to model the percent conversion of the NO to NO{sub 2}, C{sub 2}H{sub 4}, CH{sub 4}, CO and CO{sub 2} concentrations showed excellent agreement with the experimental data, thereby validating the ethylene oxidation mechanism. Reaction pathway analysis and logarithmic sensitivity analysis were combined to analyze the ethylene oxidation structure and HO{sub 2} production process. The analysis revealed the primary ethylene oxidation pathway has the potential to form two HO{sub 2} radicals per ethylene consumed, thus making the ethylene a significant agent in promoting conversion of NO to NO{sub 2}. The secondary ethylene oxidation pathway is a potent chain branching process which furthers ethylene …

Pulses of 140 GHz microwaves have been produced at a 2 kHz rate using the ETA-III induction linac and IMP wiggler. The accelerator was run in bursts of up to 50 pulses at 6 MeV and greater than 2 kA peak current. A feedback timing control system was used to synchronize acceleration voltage pulses with the electron beam, resulting in sufficient reduction of the corkscrew and energy sweep for efficient FEL operation. Peak microwave power for short bursts was in the range 0.5--1.1 GW, which is comparable to the single-pulse peak power of 0.75--2 GW. FEL bursts of more than 25 pulses were obtained.

Triangulations without large angles have a number of applications in numerical analysis and computer graphics. In particular, the convergence of a finite element calculation depends on the largest angle of the triangulation. Also, the running time of a finite element calculation is dependent on the triangulation size, so having a triangulation with few Steiner points is also important. Bern, Dobkin and Eppstein pose as an open problem the existence of an algorithm to triangulate a planar straight-line graph (PSLG) without large angles using a polynomial number of Steiner points. We solve this problem by showing that any PSLG with {upsilon} vertices can be triangulated with no angle larger than 7{pi}/8 by adding O({upsilon}{sup 2}log {upsilon}) Steiner points in O({upsilon}{sup 2} log{sup 2} {upsilon}) time. We first triangulate the PSLG with an arbitrary constrained triangulation and then refine that triangulation by adding additional vertices and edges. Some PSLGs require {Omega}({upsilon}{sup 2}) Steiner points in any triangulation achieving any largest angle bound less than {pi}. Hence the number of Steiner points added by our algorithm is within a log {upsilon} factor of worst case optimal. We note that our refinement algorithm works on arbitrary triangulations: Given any triangulation, we show how to …

'A series of subcritical noise measurements were performed on fresh and spent University of Missouri Research Reactor fuel assemblies. These experimental measurements were performed for the purposes of providing benchmark quality data for validating transport theory computer codes and nuclear cross-section data used to perform criticality safety analyses for highly enriched, uranium-aluminum Material Test Reactor fuel assemblies. A mechanical test rig was designed and built to hold up to four fuel assemblies and neutron detectors in a subcritical array. The rig provided researchers with the ability to evaluate the reactivity effects of variable fuel/detector spacing, fuel rotation, and insertion of metal reflector plates into the lattice.'

'Engineers at the Savannah River Technology Center have designed, built, and installed a fully automated small field-of-view, lens-coupled, digital radiography imaging system. The system is installed in one of the Savannah River Site''s production facilities to be used for the evaluation of production components. Custom software routines developed for the system automatically acquire, enhance, and diagnostically evaluate critical geometric features of various components that have been captured radiographically. Resolution of the digital radiograms and accuracy of the acquired measurements approaches 0.001 inches. To date, there has been zero deviation in measurement repeatability. The automated image acquisition methodology will be discussed, unique enhancement algorithms will be explained, and the automated routines for measuring the critical component features will be presented. An additional feature discussed is the independent nature of the modular software components, which allows images to be automatically acquired, processed, and evaluated by the computer in the background, while the operator reviews other images on the monitor. System components were also a key in gaining the required image resolution. System factors such as scintillator selection, x-ray source energy, optical components and layout, as well as geometric unsharpness issues are considered in the paper. Finally the paper examines the numerous quality …

The success of in-situ transmission electron microscopy experimentation is often dictated by proper specimen preparation. We report here a novel technique permitting the production of cross-sectioned tensile specimens of multilayered films for in-situ deformation studies. Of primary importance in the development of this technique is the production of an electron transparent micro-gauge section using focused ion beam technology. This microgauge section predetermines the position at which plastic deformation is initiated; crack nucleation, growth and failure are then subsequently observed.

As part of the Soviet-Designed Reactor Safety (SDRS) element of the International Nuclear Safety Program (INSP), the US Department of Energy (US DOE) is funding a plant safety evaluation (PSE) project for the Novovoronezh Nuclear Power Plant (NvNPP). The Novovoronezh PSE Project is a multi-faceted project with participants from sixteen different international organizations from five different countries scattered across eleven time zones. The purpose of this project is to provide a thorough Probabilistic Risk Analysis (PRA) and Deterministic Safety Analysis (DSA) for Units 3 and 4 of the NvNPP. In addition, this project provides assistance to the operation organizations in meeting their international commitments in support of safety upgrades, and their regulatory requirements for the conduct of safety analyses. Managing this project is a complex process requiring numerous management tools, constant monitoring, and effective communication skills. Employing management tools to resolve unanticipated problems one of the keys to project success. The overall scope, programmatic context, objectives, project interactions, communications, practical hindrances, and lessons learned from the challenging performance of the PSE project are summarized in this paper.

Experimental results from the pilot scale electrorefiner (Mark-IV ER) treating spent nuclear fuel are reported in this article. The electrorefining processes were carried out in a LiCl-KCl-UCl{sub 3} electrolyte. It has been noted that spool of molten cadmium below the electrolyte plays an important role in the electrorefining operations. In addition, formations of electrical shorting path between anode baskets and the electrorefiner vessel were observed, which lessened the uranium dissolution process from anode baskets, however appeared to improve the morphology of cathode deposit. The FIDAP simulation code was used to calculate the electrical potential field distributions and the potential gradient near the cathode. The effect of the electrical shorting between anode baskets and electrorefiner vessel on the morphology of cathode products is discussed.

A round robin test program was conducted with a glass that was developed for use as a standard test material for acceptance testing of low-activity waste glasses made with Hanford tank wastes. The program was conducted to measure the between-laboratory reproducibility of composition analysis and durability test results. Participants were free to select the methods used to analyze the glass composition. The durability tests closely followed the Product Consistency Test (PCT) Method A, except that tests were conducted at both 40 and 90 C, and parallel tests with a reference glass were not required. Samples that had been crushed, sieved, and washed to remove fines were provided to participants for tests and analyses. The results are presented in this paper. While the results are still being analyzed, the reproducibility of both the composition and PCTs results compare favorably with the results of round robins conducted with other glasses.

The author argues that the d{sub x{sup 2}{minus}y{sup 2}}-wave superconductor is marginally stable in the presence of external perturbations. Subjected to the external perturbations by magnetic impurities, it develops a secondary component of the gap, complex d{sub xy}, to maximize the coupling to impurities and lower the total energy. The secondary d{sub xy} component exists at high temperatures and produces the full gap {approximately} 20K in the single particle spectrum around each impurity, apart from impurity induced broadening. At low temperatures the phase ordering transition into global d{sub x{sup 2}{minus}y{sup 2}} + id{sub xy} state occurs.

Poroelasticity is the theoretical framework used to describe the coupled processes which occur when a fluid bearing porous material is deformed by a stress field. The theoretical basis for the treatment of problems in poroelasticity has been derived in an extensive body of work over the last fifty years, most notably by Biot. Many of Biot`s successors have attempted to find relationships between the physical properties of the material to be analyzed and the Biot coefficients. Our approach to this problem has both theoretical and experimental components. The general theoretical objective is to produce estimates of the Biot coefficients which are more realistic e.g.. are not limited by assumptions which preclude their use for real earth materials. Experiments are designed to measure the coefficients (or parameters which are directly related to them) which have not been measured as yet to provide new insight for improving the theory of poroelasticity. The experimental program is designed to determine the mechanical and transport properties of a well characterized set of synthetic and natural sandstones from static to ultrasonic frequencies.

The proposed Savannah River Site (SRS) Wetlands Restoration Project area is located in Barnwell County, South Carolina on the southwestern boundary of the SRS Reservation. The swamp covers about 40.5 km2 and is bounded to the west and south by the Savannah River and to the north and east by low bluffs at the edge of the Savannah River floodplain. Water levels within the swamp are determined by stage along the Savannah River, local drainage, groundwater seepage, and inflows from four tributaries, Beaver Dam Creek, Fourmile Branch, Pen Branch, and Steel Creek. Historic discharges of heated process water into these tributaries scoured the streambed, created deltas in the adjacent wetland, and killed native vegetation in the vicinity of the delta deposits. Future releases from these tributaries will be substantially smaller and closer to ambient temperatures. One component of the proposed restoration project will be to reestablish indigenous wetland vegetation on the Pen Branch delta that covers about 1.0 km2. Long-term predictions of water levels within the swamp are required to determine the characteristics of suitable plants. The objective of the study was to predict water levels at various locations within the proposed SRS Wetlands Restoration Project area for a range …

We present results of numerical studies of the Landau-Ginzburg dynamics of the order parameter in one-dimensional models inspired by the condensed matter analogues of cosmological phase transitions. The main goal of our work is to show that, as proposed by one of us, the density of the frozen-out topological defects is set by the competition between the quench rate - the rate at which the phase transition is taking place - and the relaxation rate of the order parameter. In other words, the characteristic domain size, which determines the typical separation of topological defects in the new broken symmetry phase, is of the order of the correlation length at the instant at which the relaxation timescale of the order parameter equals the time remaining to the phase transition. In estimating the size of topological domains, this scenario shares with the original Kibble mechanism the idea that topological defects will form along the boundaries of independently selected regions of the new broken symmetry vacuum. However, it derives the size of such domains from non-equilibrium aspects of the transition (quench rate), as opposed to Kibble`s original proposal in which their size was estimated from the Ginzburg temperature above which thermally activated symmetry …

This study presents a methodology to estimate the maximum concentrations of flammable gases (ammonia, hydrogen, and methane) which could exist in the vapor space of a double-contained receiver tank (DCRT). DCRTs are temporary storage tanks which receive highly radioactive liquid wastes from salt well pumping of Hanford single-shell tanks (SST). The methodology of this study could be used in other applications involving the storage and transfer of radioactive liquid wastes which generate or contain various dissolved flammable gases.

Magnetic Linear Dichroism in Angular Distributions (MLDAD) from Photoelectron Emission was used to probe the nature of Resonant Photoemission. Gd 5p and Gd 4f emission were investigated. Using novel theoretical simulations, we were able to show that temporal matching is a requirement for ``True`` Resonant Photoemission, where the Resonant Photoemission retains the characteristics of Photoelectron Emission.

Using precisely controlled laboratory conditions we have begun to establish a spectral catalogue of the intermediate ionization states of iron, Fe IX - Fe XXIV, in the extreme ultraviolet. The measurements are being performed in support of the development of reliable modeling codes for the analysis of data from the Extreme Ultraviolet Explorer and future space astrophysics missions sensitive to extreme ultraviolet radiation. They aim to resolve the controversies surrounding the short-wavelength spectra of stellar coronae. Preliminary measurements showing the wealth of iron lines in the 50-120 {Angstrom} region are presented.

Although the use of ionizing radiation for the treatment of benign lesions such as keloids has been available for nearly one hundred years, only recently have the cost effective benefits of such technology for the inhibition of arterial restenosis following controlled vessel damage from balloon angioplasty been fully realized. In particular, the use of balloons filled with solutions of beta-emitting radioisotopes for vessel irradiation provide the benefit of uniform vessel irradiation. Use of such contained ("unsealed") sources is expected to represent a new opportunity for nuclear medicine physicians working in conjunction with interventional cardiologists to provide this new approach for restenosis therapy.

Casing deformation in wells is a common problem in many geothermal fields. Casing remediation is necessary to keep wells in production and occasionally, to even enter the well for an approved plug and abandonment procedure. The costly alternative to casing remediation is to incur the expense of drilling a new well to maintain production or drilling a well to intersect a badly damaged well below the deformation for abandonment purposes. The U.S. Department of Energy and the Geothermal Drilling Organization sponsor research and development work at Sandia National Laboratories in an effort to reduce these remediation expenditures. Sandia, in cooperation with Halliburton Energy Services, has developed a low cost, commercially available, bridge-plug-type packer for use in geothermal well environments. This report documents the development and testing of this tool for use in casing remediation work.

Solar cells made from III-V materials have achieved efficiencies greater than 30%. Effectively ideal passivation plays an important role in achieving these high efficiencies. Standard modeling techniques are applied to Ga0.5In0.5P solar cells to show the effects of passivation. Accurate knowledge of the absorption coefficient is essential (see appendix). Although ultralow (<2 cm/s) interface recombination velocities have been reported, in practice, it is difficult to achieve such low recombination velocities in solar cells because the doping levels are high and because of accidental incorporation of impurities and dopant diffusion. Examples are given of how dopant diffusion can both help and hinder interface passivation, and of how incorporation of oxygen or hydrogen can cause problems.

This Proceedings Volume includes the technical papers that were presented during the Seventeenth Symposium on Energy Engineering Sciences on May 13-14, 1999, at Argonne National Laboratory, Argonne, Illinois. The Symposium was structured into seven technical sessions, which included 25 individual presentations followed by discussion and interaction with the audience. A list of participants is appended to this volume. The DOE Office of Basic Energy Sciences (BES), of which Engineering Research is a component program, is responsible for the long-term, mission-oriented research in the Department. The Office has prime responsibility for establishing the basic scientific foundation upon which the Nation's future energy options will be identified, developed, and built. BES is committed to the generation of new knowledge necessary to solve present and future problems regarding energy exploration, production, conversion, and utilization, while maintaining respect for the environment. Consistent with DOE/BES mission, the Engineering Research Program is charged with the identification, initiation, and management of fundamental research on broad, generic topics addressing energy-related engineering problems. Its stated goals are to improve and extend the body of knowledge underlying current engineering practice so as to create new options for enhancing energy savings and production, prolonging the useful life of energy-related structures and …

The objectives of the biosphere modeling efforts are to assess how radionuclides potentially released from the proposed repository could be transported through a variety of environmental media. The study of these transport mechanisms, referred to as pathways, is critical in calculating the potential radiation dose to man. Since most of the existing and pending regulations applicable to the Project are radiation dose based standards, the biosphere modeling effort will provide crucial technical input to support the Viability Assessment (VA), the Working Draft of License Application (WDLA), and the Environmental Impact Statement (EIS).

In this study we use spectroscopy and x-ray imaging to investigate the macroscopic plasma flow in mm-sized laser-produced hohlraum plasmas. By using multiple diagnostics to triangulate the emission on a single experiment, we can pinpoint the position of dopants placed inside the hohlraum. X-ray emission from the foil has been used in the past to measure electron temperature. Here we analyze the spatial movement of dopant plasmas for comparison to hydrodynamic calculations.

This Proceedings Volume includes the technical papers that were presented during the Sixteenth Symposium on Energy Engineering Sciences on May 13--15, 1998, at Argonne National Laboratory, Argonne, Illinois. The Symposium was structured into eight technical sessions, which included 30 individual presentations followed by discussion and interaction with the audience. A list of participants is appended to this volume. The DOE Office of Basic Energy Sciences (BES), of which Engineering Research is a component program, is responsible for the long-term, mission-oriented research in the Department. The Office has prime responsibility for establishing the basic scientific foundation upon which the Nation's future energy options will be identified, developed, and built. BES is committed to the generation of new knowledge necessary to solve present and future problems regarding energy exploration, production, conversion, and utilization, while maintaining respect for the environment. Consistent with the DOE/BES mission, the Engineering Research Program is charged with the identification, initiation, and management of fundamental research on broad, generic topics addressing energy-related engineering problems. Its stated goals are to improve and extend the body of knowledge underlying current engineering practice so as to create new options for enhancing energy savings and production, prolonging the useful life of energy-related structures …