Researchers at the Department of Energy's Savannah River Technology Center are using advanced microscopy techniques to understand the effects of trace organic chemical additions on nuclear waste slurry flow properties. Trace organic chemicals, surfactants (rheology modifiers), are being used in all types of industries to modify the flow properties of various commercial chemicals. Nuclear waste treatment at the Department of Energy's weapons production facilities, Savannah River Site and Hanford Reservation, is limited by the viscosity of the nuclear waste slurries as the material is processed through a variety of waste treatment and immobilization processes. The picture was taken using a laser scanning confocal microscope.

Increased biomass burning (e.g., forest fires, controlled burns, etc.) and anthropogenic emissions into the earth's atmosphere in the past century have led to much debate with regard to greenhouse gases, atmospheric carbon buildup, aerosol increases, and global warming. Atmospheric aerosols are linked to reduced air quality and visibility (V) in many parts of the world. In south-central South Carolina visibility reduction has been responsible for traffic fatalities on public highways, with resulting lawsuits against governmental entities. Congress passed the Clean Air Act in 1963, with amendments in 1970, 1977, and 1990 to improve air quality. The actual implementation of the Clean Air Act has been an intermittent process because of litigation over some provisions of the Act. However, it is reasonable to assume that visibility has improved in the U.S. over the past decades due to implementation of the Clean Air Act's provisions. In this study visibility data have been acquired for seven weather stations along or near the U.S. East Coast to study how conditions have changed from the 1980s to the 1990s.

We investigate the appearance of closed timelike curves in quotients of plane waves along spacelike isometries. First we formulate a necessary and sufficient condition for a quotient of a general spacetime to preserve stable causality. We explicitly show that the plane waves are stably causal; in passing, we observe that some pp-waves are not even distinguishing. We then consider the classification of all quotients of the maximally supersymmetric ten-dimensional plane wave under a spacelike isometry, and show that the quotient will lead to closed timelike curves iff the isometry involves a translation along the u direction. The appearance of these closed timelike curves is thus connected to the special properties of the light cones in plane wave spacetimes. We show that all other quotients preserve stable causality.

Planar flames are intrinsically unstable in open domains due to the thermal expansion across the burning front--the Landau-Darrieus instability. This instability leads to wrinkling and growth of the flame surface, and corresponding acceleration of the flame, until it is stabilized by cusp formation. We look at the Landau-Darrieus in stability for C/O thermonuclear flames at conditions relevant to the late stages of a Type Ia supernova explosion. Two-dimensional direct numerical simulations of both single-mode and multi-mode perturbations using a low Mach number hydrodynamics code are presented. We show the effect of the instability on the flame speed as a function of both the density and domain size, demonstrate the existence of the small scale cutoff to the growth of the instability, and look for the proposed breakdown of the non-linear stabilization at low densities. The effects of curvature on the flame as quantified through measurements of the growth rate and computation of the corresponding Markstein number. While accelerations of a few percent are observed, they are too small to have any direct outcome on the supernova explosion.

M-shell spectra of W ions have been produced at the Livermore EBIT-II electron beam ion trap at different energies of the electron beam. A survey has been performed for 2.4 keV, 2.8 keV, 3.6 keV and for steps in energy of 100 eV over the 3.9-4.6 keV energy range. The analysis of 11 W spectra has shown the presence of a wide variety of ionization stages from Se-like to Cr-like W; the appearances of these ionization stages correlate well with the energy of their production. The present paper focuses on the identification of 63 experimental features of W ions in a spectral region from 5 to 6 Angstrom using calculations with inclusion of all ionization stages matching this spectral region. The majority of lines in all spectra have been identified and assigned to the 4f {yields} 3d and 4d {yields} 3p transitions. This is the first work that lists a comprehensive identification of so many resolved spectral features of M-shell transitions in W ions recorded in such detail in the laboratory.

The National Ignition Facility (NIF), currently under construction at the Lawrence Livermore National Laboratory, is a stadium-sized facility containing a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter diameter target chamber with room for nearly 100 experimental diagnostics. When completed, NIF will be the world's largest and most energetic laser experimental system, providing an international center to study inertial confinement fusion and the physics of matter at extreme energy densities and pressures. NIF's 192 energetic laser beams will compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. Other NIF experiments will allow the study of physical processes at temperatures approaching 10{sup 8} K and 10{sup 11} Bars, conditions that exist naturally only in the interior of stars, planets and in nuclear weapons. NIF is now entering the first phases of its laser commissioning program. This paper provides a detailed look the NIF laser systems and the results of recent laser commissioning shots. We discuss plans for experiments using the first laser beams of NIF and plans for future uses of NIF, including short pulse laser capability on NIF for high energy, high brightness radiographic x-ray backlighters for physics …

Oxide thickness and composition averaged over a few square millimeter has been measured with nm thickness resolution by diffuse reflectance fourier transform infrared (FTIR) spectroscopy. {mu}-Raman spectroscopy has been done on powders and bulk samples in the past, and can now be done on surfaces layers with {micro}m lateral and depth resolution using con-focal microscopy. Here we apply con-focal-microscopy-based {mu}-Raman spectroscopy to a freshly polished/lightly oxidized and to heavily oxidized uranium to determine its sensitivity. The spectra show that {mu}-Raman spectroscopy does detect oxide thickness and oxide composition with high sensitivity.

Renewed interest in hydrogen storage materials has resulted in the development of Ti-doped NaAlH{sub 4}. Different doping methods such as mechanical milling with powdered TiCl{sub 3}, or wet doping in solvents such as tetrahydrofuran (THF), yield enhanced kinetics. Still, the location and action of the Ti dopant is an open question. In order to address titanium substitution in the bulk, we present lattice parameter measurements of crushed single crystals which were exposed to Ti during growth. Rietveld refinements suggest that the titanium does not appear to enter the bulk by this method of exposure. Therefore, reaction products are investigated by x-ray diffraction of completely reacted samples of solvent-mixed versus mechanically milled 3 NaAlH{sub 4}+TiCl{sub 3}. Formation of TiAl{sub 3} is observed in mechanically milled materials, but not solution mixed samples, where bonding to THF likely stabilizes Ti-based nanoclusters. The Ti in these clusters is activated by mechanical milling.

In recent years, the development of Ti-doped NaAlH{sub 4} as a hydrogen storage material has gained attention because of its large weight percentage of hydrogen ({approx}5%) compared to traditional interstitial hydrides. The addition of transition-metal dopants, in the form of Ti-halides, such as TiCl{sub 3}, dramatically improves the kinetics of the absorption and desorption of hydrogen from NaAlH{sub 4}. However, the role that Ti plays in enhancing the absorption and desorption of H{sub 2} is still unknown. In the present study, {sup 27}Al, {sup 23}Na, and {sup 1}H MAS (Magic Angle Spinning) NMR (Nuclear Magnetic Resonance) has been performed to understand the titanium speciation in Ti-doped NaAlH{sub 4}. All experiments were performed on a sample of crushed single crystals exposed to Ti during growth, a sample of solvent-mixed 4TiCl{sub 3} + 112NaAlH{sub 4}, a reacted sample of solvent-mixed TiCl{sub 3} + {sup 3}NaAlH{sub 4} with THF, and a reacted sample of ball-milled TiCl3 + 3NaAlH{sub 4}. The {sup 27}Al MAS NMR has shown differences in compound formation between solvent-mixed TiCl{sub 3} + 3NaAlH{sub 4} with THF and the mechanically ball-milled TiCl{sub 3} + 3NaAlH{sub 4}. {sup 27}Al MAS NMR of the mechanically ball-milled mixture of fully-reacted TiCl{sub 3} + 3NaAlH{sub …

ALE3D simulations are presented for the thermal explosion of Comp B (RDX,TNT) in a Scaled Thermal Explosion Experiment (STEX). Candidate models and numerical strategies are being tested using the ALE3D code which simulates the coupled thermal, mechanical, and chemical behavior during heating, ignition, and explosion. The mechanical behavior of the solid constituents is represented by a Steinberg-Guinan model while polynomial and gamma-law expressions are used for the equation of state of the solid and gas species, respectively. A gamma-law model is employed for the air in gaps, and a mixed material model is used for the interface between air and explosive. A three-step chemical kinetics model is used for each of the RDX and TNT reaction sequences during the heating and ignition phases, and a pressure-dependent deflagration model is employed during the rapid expansion. Parameters for the three-step kinetics model are specified using measurements of the One-Dimensional-Time-to-Explosion (ODTX), while measurements for burn rate are employed to determine parameters in the burn front model. We compare model predictions to measurements for temperature fields, ignition temperature, and tube wall strain during the heating, ignition, and explosive phases.

Cementitious waste forms (CWFs) are an important component of the strategy to immobilize high-level nuclear waste resulting from plutonium production by the U.S. Department of Energy (DOE). Technetium (99Tc) is an abundant fission product of particular concern in CWFs due to the high solubility and mobility of pertechnetate, TcO4-, the stable form of technetium in aerobic environments. CWFs can more effectively immobilize 99Tc if they contain additives that reduce mobile TcO4- to immobile Tc(IV) species. Leaching of 99Tc from reducing CWFs that contain Tc(IV) is much slower than for CWFs containing TcO4-. Previous X-ray absorption fine structure (XAFS) studies showed that the Tc(IV) species were oxidized to TcO4- in reducing grout samples prepared on a laboratory scale. Whether the oxidizer was atmospheric O2 or NO3- in the waste simulant was not determined. In actual CWFs, rapid oxidation of Tc(IV) by NO3- would be a concern, whereas oxidation by atmospheric O2 would be of less concern due to the slow diffusion and reaction of O2 with the reducing CWF. To address this uncertainty, two series of reducing grouts were prepared using TcO4- containing waste simulants with and without NO3-. In the first series of samples, the TcO4- was completely reduced using …

The Savannah River Technology Center's (SRTC) Atmospheric Technologies Group (ATG) has operated nine 61-m tower sites including the Central Climatology (CC) tower which is located near the center of the Savannah River Site (SRS) since 1985. Data from the weather instruments on this tower have provided answers to questions involving risk analyses, dose studies, forecast verifications, and wind/temperature conditions during extreme events and planned tests. Most recently, data from these towers are being used for initial and boundary conditions for computationally intensive numerical simulations using mesoscale forecasting models that are run on a three-hourly basis by ATG for SRS and the surrounding vicinity. We found that a series of wind roses based on relatively short time scales (from two weeks to one hour) were a convenient method to depict the predominant wind speeds and directions at anemometer sites in the Southeast operated by the NWS. That report also revealed some interesting spatial and temporal relationships among thirteen NWS stations in the Carolinas, Georgia, and Florida. Our study here will focus on the CC tower to show changes in the wind speed and direction distributions with height during diurnal and annual cycles. This study will concentrate on mean wind speed and …

{lg_bullet} The focus was on fundamental actinide science and its role. {lg_bullet} History- none except the Nuclear Waste Management Symposia {lg_bullet} Joint Sessions- none but we are open to it in the future. {lg_bullet} Tutorials- none but we are open to it in the future. {lg_bullet} 3 days: 16 Invited talks; 36 Contributed Talks; 10 Posters

The Savannah River Site has used Kanne ionization chambers since the late 1950's to monitor for airborne tritium in reactor facilities. Two Kanne monitors indicated elevated airborne tritium levels while monitoring a non-ventilated room used to store tritiated liquid moderator. Subsequent air sample analysis failed to reveal the presence of airborne tritium. It was suspected that elevated radon levels caused the Kanne monitors to falsely indicate tritium activity. Two commercially available monitoring systems were used to quantify radon levels in the storage room. Measurements performed during this evaluation found that radon caused the Kanne monitors in the storage room to falsely indicate the presence of airborne tritium. A side-by-side comparison of a filtered versus an unfiltered Kanne monitor found that a high efficiency particulate filter reduced monitor response to near background under high radon conditions. It was recommended that a high efficiency filter be installed on the dedicated storage room Kanne monitor and that the room be de-posted as an Airborne Radioactivity Area. It was also found that the Kanne monitors would detect a spill from a single drum of moderator within minutes and the dose rate due to tritium exposure at 20 hours following this spill would be 4.56 …

We report on three-dimensional fluorescence imaging of micron-size faceted crystals precipitated from solutions of CdSe nanocrystals. Such crystals have previously been suggested to be superlattices of CdSe quantum dots [1,2]. Possible applications for these materials include their use in optical and optoelectronic devices. The micron-size crystals were grown by slow evaporation from toluene solutions of CdSe nanocrystals in the range of 3-6 nm, produced by traditional wet-chemistry techniques. By using a confocal microscope with laser illumination, three-dimensional raster-scanning and synchronized hyper-spectral detection, we have generated spatial profiles of the fluorescence emission intensity and spectrum. The fluorescence data of the micro-crystals were compared with spectra of individual nanocrystals obtained from the same solution. The results do not support the assertion that these microcrystals consist of CdSe superlattices.