AUTOMATING GROUNDWATER SAMPLING AT HANFORD (open access)

AUTOMATING GROUNDWATER SAMPLING AT HANFORD

Until this past October, Fluor Hanford managed Hanford's integrated groundwater program for the U.S. Department of Energy (DOE). With the new contract awards at the Site, however, the CH2M HILL Plateau Remediation Company (CHPRC) has assumed responsibility for the groundwater-monitoring programs at the 586-square-mile reservation in southeastern Washington State. These programs are regulated by the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response Compensation and Liability Act (CERCLA). The purpose of monitoring is to track existing groundwater contamination from past practices, as well as other potential contamination that might originate from RCRA treatment, storage, and disposal (TSD) facilities. An integral part of the groundwater-monitoring program involves taking samples of the groundwater and measuring the water levels in wells scattered across the site. More than 1,200 wells are sampled each year. Historically, field personnel or 'samplers' have been issued pre-printed forms that have information about the well(s) for a particular sampling evolution. This information is taken from the Hanford Well Information System (HWIS) and the Hanford Environmental Information System (HEIS)--official electronic databases. The samplers used these hardcopy forms to document the groundwater samples and well water-levels. After recording the entries in the field, the samplers turned the forms …
Date: January 16, 2009
Creator: CW, CONNELL; RD, HILDEBRAND; SF, CONLEY & DE, CUNNINGHAM
System: The UNT Digital Library
Development of pseudo-random binary gratings and arrays for calibration of surface profile metrology tools (open access)

Development of pseudo-random binary gratings and arrays for calibration of surface profile metrology tools

Optical Metrology tools, especially for short wavelength (EUV and X-Ray), must cover a wide range of spatial frequencies from the very low, which affects figure, to the important mid-spatial frequencies and the high spatial frequency range, which produces undesirable flair. A major difficulty in using surface profilometers arises due to the unknown Modulation Transfer Function (MTF) of the instruments. Therefore, accurate calibration of profilometers, the understanding of their MTF limitations, and cross calibration between tools represents a considerable challenge for quantitative optical metrology. In previous work the instrumental MTF of a surface profiler was precisely measured using reference test surfaces based on binary pseudo-random (BPR) gratings. Here, they present results of fabricating and using two-dimensional (2D) BPR arrays that allow for a direct 2D calibration of the instrumental MTF. BPR sequences are widely used in engineering and communication applications such as Global Position System, and wireless communication protocol. The ideal BPR pattern has a flat 'white noise' response over the entire range of spatial frequencies of interest. The BPR array used here is based on the Uniformly Redundant Array prescription initially used for x-ray and gamma ray astronomy applications. The URA's superior imaging capability originates from the fact that its …
Date: January 16, 2009
Creator: Barber, Samuel K.; Soldate, Paul; Anderson, Erik; Cambie, Rosanna; McKinney, Wayne R.; Takacs, Peter Z. et al.
System: The UNT Digital Library
ESTABLISHING FINAL END STATE FOR A RETIRED NUCLEAR WEAPONS PRODUCTION REACTOR; COLLABORATION BETWEEN STAKEHOLDERS, REGULATORS AND THE FEDERAL GOVERNMENT (open access)

ESTABLISHING FINAL END STATE FOR A RETIRED NUCLEAR WEAPONS PRODUCTION REACTOR; COLLABORATION BETWEEN STAKEHOLDERS, REGULATORS AND THE FEDERAL GOVERNMENT

The Savannah River Site (SRS) is a 310-square-mile United States Department of Energy nuclear facility located along the Savannah River (SRS) near Aiken, South Carolina. Nuclear weapons material production began in the early 1950s, utilizing five production reactors. In the early 1990s all SRS production reactor operations were terminated. The first reactor closure end state declaration was recently institutionalized in a Comprehensive Environmental Response and Compensation and Liability Act (CERCLA) Early Action Record of Decision. The decision for the final closure of the 318,000 square foot 105-P Reactor was determined to be in situ decommissioning (ISD). ISD is an acceptable and cost effective alternative to off-site disposal for the reactor building, which will allow for consolidation of remedial action wastes generated from other cleanup activities within the P Area. ISD is considered protective by the regulators, U. S. Environmental Protection Agency (US EPA) and the South Carolina Department of Health and Environmental Control (SCDHEC), public and stakeholders as waste materials are stabilized/immobilized, and radioactivity is allowed to naturally decay, thus preventing future exposure to the environment. Stakeholder buy-in was critical in the upfront planning in order to achieve this monumental final decision. Numerous public meetings and workshops were held in …
Date: January 16, 2009
Creator: Bergren, C
System: The UNT Digital Library
Development of pseudo-random binary gratings and arrays for calibration of surface profile metrology tools (open access)

Development of pseudo-random binary gratings and arrays for calibration of surface profile metrology tools

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Date: January 16, 2009
Creator: Barber, Samuel K.; Soldate, Paul; Anderson, Erik; Cambie, Rosanna; McKinney, Wayne R.; Takacs, Peter Z. et al.
System: The UNT Digital Library
Findings of the US Research Needs Workshop on the Topic of Fusion Power (open access)

Findings of the US Research Needs Workshop on the Topic of Fusion Power

The US Department of Energy, Office of Fusion Energy Sciences (OFES) conducted a Research Needs Workshop, referred to as ReNeW, in June 2009. The information developed at this workshop will help OFES develop a plan for US fusion research during the ITER era, roughly the next two decades. The workshop was organized in five Themes, one of which was Harnessing Fusion Power (or Fusion Power for short). The top level goal of the Fusion Power Theme was to identify the research needed to develop the knowledge to design and build, with high confidence, robust and reliable systems that can convert fusion products to useful forms of energy in a reactor environment, including a self-sufficient supply of tritium fuel. Each Theme was subsequently subdivided into Panels to address specific topics. The Fusion Power Panel topics were: fusion fuel cycle; power extraction; materials science; safety and environment; and reliability, availability, maintainability and inspectability (RAMI). Here we present the key findings of the Fusion Power Theme.
Date: September 16, 2009
Creator: Meier, W. R.; Raffray, A. R.; Kurtz, R. J.; Morley, N. B.; Reiersen, W. T.; Sharpe, P. et al.
System: The UNT Digital Library
Using aberration test patterns to optimize the performance of EUV aerial imaging microscopes (open access)

Using aberration test patterns to optimize the performance of EUV aerial imaging microscopes

The SEMATECH Berkeley Actinic Inspection Tool (AIT) is a prototype EUV-wavelength zoneplate microscope that provides high quality aerial image measurements of EUV reticles. To simplify and improve the alignment procedure we have created and tested arrays of aberration-sensitive patterns on EUV reticles and we have compared their images collected with the AIT to the expected shapes obtained by simulating the theoretical wavefront of the system. We obtained a consistent measure of coma and astigmatism in the center of the field of view using two different patterns, revealing a misalignment condition in the optics.
Date: June 16, 2009
Creator: Mochi, Iacopo; Goldberg, Kenneth A.; Miyakawa, Ryan; Naulleau, Patrick; Han, Hak-Seung & Huh, Sungmin
System: The UNT Digital Library
Material properties limiting the performance of CZT gamma-ray detectors (open access)

Material properties limiting the performance of CZT gamma-ray detectors

CdZnTe (CZT) nuclear radiation detectors are advanced sensors that utilize innovative technologies developed for wide band-gap semiconductor industry and microelectronics. They open opportunities for new types of room-temperature operating, field deployable instruments that provide accurate identification of potential radiological threats and timely awareness for both the civilian and military communities. Room-temperature radiation detectors are an emerging technology that relies on the use of high-quality CZT crystals whose availability is currently limited by material non-uniformities and the presence of extended defects. To address these issues, which are most critical to CZT sensor developments, we developed X-ray mapping and IR transmission microscopy systems to characterize both CZT crystals and devices. Since a customized system is required for such X-ray measurements, we use synchrotron radiation beams available at BNL's National Synchrotron Light Source. A highly-collimated and high-intensity X-ray beam supports measurements of areas as small as 10 x 10 {micro}m{sup 2}, and allowed us to see fluctuations in collected charge over the entire area of the detector in a reasonable time. The IR microscopy system allows for 3D visualization of Te inclusions and other extended defects. In this paper, we describe the experimental techniques used in our measurements and typical results obtained from …
Date: March 16, 2009
Creator: Bolotnikov, A. E.; Babalola, S.; Camarda, G. S.; Cui, Y.; Egarievwe, S. U.; Hossain, A. et al.
System: The UNT Digital Library
Simulations of the Microwave Sky (open access)

Simulations of the Microwave Sky

We create realistic, full-sky, half-arcminute resolution simulations of the microwave sky matched to the most recent astrophysical observations. The primary purpose of these simulations is to test the data reduction pipeline for the Atacama Cosmology Telescope (ACT) experiment; however, we have widened the frequency coverage beyond the ACT bands and utilized the easily accessible HEALPix map format to make these simulations applicable to other current and near future microwave background experiments. Some of the novel features of these simulations are that the radio and infrared galaxy populations are correlated with the galaxy cluster and group populations, the primordial microwave background is lensed by the dark matter structure in the simulation via a ray-tracing code, the contribution to the thermal and kinetic Sunyaev-Zel'dovich (SZ) signals from galaxy clusters, groups, and the intergalactic medium has been included, and the gas prescription to model the SZ signals has been refined to match the most recent X-ray observations. The cosmology adopted in these simulations is also consistent with the WMAP 5-year parameter measurements. From these simulations we find a slope for the Y{sub 200} - M{sub 200} relation that is only slightly steeper than self-similar, with an intrinsic scatter in the relation of {approx} …
Date: December 16, 2009
Creator: Sehgal, Neelima; /KIPAC, Menlo Park; Bode, Paul; /Princeton U., Astrophys. Sci. Dept.; Das, Sudeep; /Princeton U., Astrophys. Sci. Dept. /Princeton U. et al.
System: The UNT Digital Library
Measurements of phi meson production in relativistic heavy-ion collisions at RHIC (open access)

Measurements of phi meson production in relativistic heavy-ion collisions at RHIC

We present results for the measurement of {phi} meson production via its charged kaon decay channel {phi} {yields} K{sup +}K{sup -} in Au + Au collisions at {radical}s{sub NN} = 62.4, 130, and 200 GeV, and in p + p and d + Au collisions at {radical}s{sub NN} = 200 GeV from the STAR experiment at the BNL Relativistic Heavy Ion Collider (RHIC). The midrapidity (|y| < 0.5) {phi} meson transverse momentum (p{sub T}) spectra in central Au + Au collisions are found to be well described by a single exponential distribution. On the other hand, the p{sub T} spectra from p + p, d + Au and peripheral Au + Au collisions show power-law tails at intermediate and high p{sub T} and are described better by Levy distributions. The constant {phi}/K{sup -} yield ratio vs beam species, collision centrality and colliding energy is in contradiction with expectations from models having kaon coalescence as the dominant mechanism for {phi} production at RHIC. The {Omega}/{phi} yield ratio as a function of p{sub T} is consistent with a model based on the recombination of thermal s quarks up to p{sub T} {approx} 4 GeV/c, but disagrees at higher transverse momenta. The measured …
Date: June 16, 2009
Creator: STAR Collaboration
System: The UNT Digital Library
Strange Bedfellows: Quantum Mechanics and Data Mining (open access)

Strange Bedfellows: Quantum Mechanics and Data Mining

Last year, in 2008, I gave a talk titled Quantum Calisthenics. This year I am going to tell you about how the work I described then has spun off into a most unlikely direction. What I am going to talk about is how one maps the problem of finding clusters in a given data set into a problem in quantum mechanics. I will then use the tricks I described to let quantum evolution lets the clusters come together on their own.
Date: December 16, 2009
Creator: Weinstein, Marvin
System: The UNT Digital Library
Modeling acid-gas generation from boiling chloride brines (open access)

Modeling acid-gas generation from boiling chloride brines

This study investigates the generation of HCl and other acid gases from boiling calcium chloride dominated waters at atmospheric pressure, primarily using numerical modeling. The main focus of this investigation relates to the long-term geologic disposal of nuclear waste at Yucca Mountain, Nevada, where pore waters around waste-emplacement tunnels are expected to undergo boiling and evaporative concentration as a result of the heat released by spent nuclear fuel. Processes that are modeled include boiling of highly concentrated solutions, gas transport, and gas condensation accompanied by the dissociation of acid gases, causing low-pH condensate. Simple calculations are first carried out to evaluate condensate pH as a function of HCl gas fugacity and condensed water fraction for a vapor equilibrated with saturated calcium chloride brine at 50-150 C and 1 bar. The distillation of a calcium-chloride-dominated brine is then simulated with a reactive transport model using a brine composition representative of partially evaporated calcium-rich pore waters at Yucca Mountain. Results show a significant increase in boiling temperature from evaporative concentration, as well as low pH in condensates, particularly for dynamic systems where partial condensation takes place, which result in enrichment of HCl in condensates. These results are in qualitative agreement with experimental …
Date: November 16, 2009
Creator: Zhang, Guoxiang; Spycher, Nicolas; Sonnenthal, Eric & Steefel, Carl
System: The UNT Digital Library
Disentangling Dark Matter Dynamics with Directional Detection (open access)

Disentangling Dark Matter Dynamics with Directional Detection

Inelastic dark matter reconciles the DAMA anomaly with other null direct detection experiments and points to a non-minimal structure in the dark matter sector. In addition to the dominant inelastic interaction, dark matter scattering may have a subdominant elastic component. If these elastic interactions are suppressed at low momentum transfer, they will have similar nuclear recoil spectra to inelastic scattering events. While upcoming direct detection experiments will see strong signals from such models, they may not be able to unambiguously determine the presence of the subdominant elastic scattering from the recoil spectra alone. We show that directional detection experiments can separate elastic and inelastic scattering events and discover the underlying dynamics of dark matter models.
Date: December 16, 2009
Creator: Lisanti, Mariangela & Wacker, Jay G.
System: The UNT Digital Library
Optimal measurement strategies for effective suppression of drift errors (open access)

Optimal measurement strategies for effective suppression of drift errors

Drifting of experimental set-ups with change of temperature or other environmental conditions is the limiting factor of many, if not all, precision measurements. The measurement error due to a drift is, in some sense, in-between random noise and systematic error. In the general case, the error contribution of a drift cannot be averaged out using a number of measurements identically carried out over a reasonable time. In contrast to systematic errors, drifts are usually not stable enough for a precise calibration. Here a rather general method for effective suppression of the spurious effects caused by slow drifts in a large variety of instruments and experimental set-ups is described. An analytical derivation of an identity, describing the optimal measurement strategies suitable for suppressing the contribution of a slow drift described with a certain order polynomial function, is presented. A recursion rule as well as a general mathematical proof of the identity is given. The effectiveness of the discussed method is illustrated with an application of the derived optimal scanning strategies to precise surface slope measurements with a surface profiler.
Date: April 16, 2009
Creator: Yashchuk, Valeriy V.
System: The UNT Digital Library
ADVANCES IN SE-79 ANALYSES ON SAVANNAH RIVER SITE RADIOACTIVE WASTE MATRICES (open access)

ADVANCES IN SE-79 ANALYSES ON SAVANNAH RIVER SITE RADIOACTIVE WASTE MATRICES

Waste cleanup efforts underway at the United States Department of Energy's (DOE) Savannah River Site (SRS) in South Carolina, as well as other DOE nuclear sites, have created a need to characterize {sup 79}Se in radioactive waste inventories. Successful analysis of {sup 79}Se in high activity waste matrices is challenging for a variety of reasons. As a result of these unique challenges, the successful quantification of {sup 79}Se in the types of matrices present at SRS requires an extremely efficient and selective separation of {sup 79}Se from high levels of interfering radionuclides. A robust {sup 79}Se radiochemical separation method has been developed at the Savannah River National Laboratory (SRNL) which is routinely capable of successfully purifying {sup 79}Se from a wide range of interfering radioactive species. In addition to a dramatic improvements in the Kd, ease, and reproducibility of the analysis, the laboratory time has been reduced from several days to only 6 hours.
Date: March 16, 2009
Creator: Diprete, D; C Diprete, C; Ned Bibler, N; Cj Bannochie, C & Michael Hay, M
System: The UNT Digital Library
Hamiltonian Light-front Field Theory Within an AdS/QCD Basis (open access)

Hamiltonian Light-front Field Theory Within an AdS/QCD Basis

Non-perturbative Hamiltonian light-front quantum field theory presents opportunities and challenges that bridge particle physics and nuclear physics. Fundamental theories, such as Quantum Chromodynamics (QCD) and Quantum Electrodynamics (QED) offer the promise of great predictive power spanning phenomena on all scales from the microscopic to cosmic scales, but new tools that do not rely exclusively on perturbation theory are required to make connection from one scale to the next. We outline recent theoretical and computational progress to build these bridges and provide illustrative results for nuclear structure and quantum field theory. As our framework we choose light-front gauge and a basis function representation with two-dimensional harmonic oscillator basis for transverse modes that corresponds with eigensolutions of the soft-wall AdS/QCD model obtained from light-front holography.
Date: December 16, 2009
Creator: Vary, J.P.; Honkanen, H.; Li, Jun; Maris, P.; U., /Iowa State; Brodsky, S.J. et al.
System: The UNT Digital Library
Ultra-high Resolution Optics for EUV and Soft X-ray Inelastic Scattering (open access)

Ultra-high Resolution Optics for EUV and Soft X-ray Inelastic Scattering

We describe a revolutionary new approach to high spectral resolution soft x-ray optics. Conventionally in the soft x-ray energy range, high spectral resolution is obtained by use of a relatively low line density grating operated in 1st order with small slits. This severely limits throughput. This limitation can be removed by use of a grating either in very high order, or with very high line density, if one can maintain high diffraction efficiency. We have developed a new technology for achieving both of these goals which should allow high throughput spectroscopy, at resolving powers of up to 106 at 1 keV. Such optics should provide a revolutionary advance for high resolution lifetime free spectroscopy, such as RIXS, and for pulse compression of chirped beams. We report recent developmental fabrication and characterization of a prototype grating optimized for 14.2 nm EUV light. The prototype grating with a 200 nm period of the blazed grating substrate coated with 20 Mo/Si bilayers with a period of 7.1 nm demonstrates good dispersion in the third order (effective groove density of 15,000 lines per mm) with a diffraction efficiency of more than 33percent.
Date: September 16, 2009
Creator: Voronov, Dmitry L.; Cambie, Rossana; Ahn, Minseung; Anderson, Erik H.; Chang, Chih-Hao; Gullikson, Eric M. et al.
System: The UNT Digital Library
Reactive Blast Waves from Composite Charges (open access)

Reactive Blast Waves from Composite Charges

Investigated here is the performance of composite explosives - measured in terms of the blast wave they drive into the surrounding environment. The composite charge configuration studied here was a spherical booster (1/3 charge mass), surrounded by aluminum (Al) powder (2/3 charge mass) at an initial density of {rho}{sub 0} = 0.604 g/cc. The Al powder acts as a fuel but does not detonate - thereby providing an extreme example of a 'non-ideal' explosive (where 2/3 of the charge does not detonate). Detonation of the booster charge creates a blast wave that disperses the Al powder and ignites the ensuing Al-air mixture - thereby forming a two-phase combustion cloud embedded in the explosion. Afterburning of the booster detonation products with air also enhances and promotes the Al-air combustion process. Pressure waves from such reactive blast waves have been measured in bomb calorimeter experiments. Here we describe numerical simulations of those experiments. A Heterogeneous Continuum Model was used to model the dispersion and combustion of the Al particle cloud. It combines the gasdynamic conservation laws for the gas phase with a dilute continuum model for the dispersed phase, as formulated by Nigmatulin. Inter-phase mass, momentum and energy exchange are prescribed by …
Date: October 16, 2009
Creator: Kuhl, A L; Bell, J B & Beckner, V E
System: The UNT Digital Library
Thermodynamic States in Explosion Fields (open access)

Thermodynamic States in Explosion Fields

Here we investigate the thermodynamic states occurring in explosion fields from the detonation of condensed explosives in air. In typical applications, the pressure of expanded detonation products gases is modeled by a Jones-Wilkins-Lee (JWL) function: P{sub JWL} = f(v,s{sub CJ}); constants in that function are fit to cylinder test data. This function provides a specification of pressure as a function of specific volume, v, along the expansion isentrope (s = constant = s{sub CJ}) starting at the Chapman-Jouguet (CJ) state. However, the JWL function is not a fundamental equation of thermodynamics, and therefore gives an incomplete specification of states. For example, explosions inherently involve shock reflections from surfaces; this changes the entropy of the products, and in such situations the JWL function provides no information on the products states. In addition, most explosives are not oxygen balanced, so if hot detonation products mix with air, they after-burn, releasing the heat of reaction via a turbulent combustion process. This raises the temperature of explosion products cloud to the adiabatic flame temperature ({approx}3,000K). Again, the JWL function provides no information on the combustion products states.
Date: October 16, 2009
Creator: Kuhl, A L
System: The UNT Digital Library
Integrated Kinetic Simulation of Laser-Plasma Interactions, Fast-Electron Generation and Transport in Fast Ignition (open access)

Integrated Kinetic Simulation of Laser-Plasma Interactions, Fast-Electron Generation and Transport in Fast Ignition

We present new results on the physics of short-pulse laser-matter interaction of kilojoule-picosecond pulses at full spatial and temporal scale, using a new approach that combines a 3D collisional electromagnetic Particle-in-Cell code with an MHD-hybrid model of high-density plasma. In the latter, collisions damp out plasma waves, and an Ohm's law with electron inertia effects neglected determines the electric field. In addition to yielding orders of magnitude in speed-up while avoiding numerical instabilities, this allows us to model the whole problem in a single unified framework: the laser-plasma interaction at sub-critical densities, energy deposition at relativistic critical densities, and fast-electron transport in solid densities. Key questions such as the multi-picosecond temporal evolution of the laser energy conversion into hot electrons, the impact of return currents on the laser-plasma interaction, and the effect of self-generated electric and magnetic fields on electron transport will be addressed. We will report applications to current experiments.
Date: November 16, 2009
Creator: Kemp, A; Cohen, B & Divol, L
System: The UNT Digital Library
Effect of flow fluctuations and nonflow on elliptic flow methods (open access)

Effect of flow fluctuations and nonflow on elliptic flow methods

We discuss how the different estimates of elliptic flow are influenced by flow fluctuations and nonflow effects. It is explained why the event-plane method yields estimates between the two-particle correlation methods and the multiparticle correlation methods. It is argued that nonflow effects and fluctuations cannot be disentangled without other assumptions. However, we provide equations where, with reasonable assumptions about fluctuations and nonflow, all measured values of elliptic flow converge to a unique mean v_2,PP elliptic flow in the participant plane and, with a Gaussian assumption on eccentricity fluctuations, can be converted to the mean v_2,RP in the reaction plane. Thus, the 20percent spread in observed elliptic flow measurements from different analysis methods is no longer mysterious.
Date: April 16, 2009
Creator: Ollitrault, Jean-Yves; Poskanzer, Arthur M. & Voloshin, Sergei A.
System: The UNT Digital Library
National Ignition Campaign Hohlraum Energetics (open access)

National Ignition Campaign Hohlraum Energetics

The first series of experiments on the National Ignition Facility (NIF) [E. I. Moses, R. N. Boyd, B. A. Remington, C. J. Keane, and R. Al-Ayat, 'The National Ignition Facility: ushering in a new age for high energy density science,' Phys. Plasmas 16, 041006 (2009)] tested ignition hohlraum 'energetics,' a term described by four broad goals: (1) Measurement of laser absorption by the hohlraum; (2) Measurement of the x-ray radiation flux (T{sub RAD}{sup 4}) on the surrogate ignition capsule; (3) Quantitative understanding of the laser absorption and resultant x-ray flux; and (4) Determining whether initial hohlraum performance is consistent with requirements for ignition. This paper summarizes the status of NIF hohlraum energetics experiments. The hohlraum targets and experimental design are described, as well as the results of the initial experiments. The data demonstrate low backscattered energy (< 10%) for hohlraums filled with helium gas. A discussion of our current understanding of NIF hohlraum x-ray drive follows, including an overview of the computational tools, i.e., radiation-hydrodynamics codes, that have been used to design the hohlraums. The performance of the codes is compared to x-ray drive and capsule implosion data from the first NIF experiments. These results bode well for future NIF …
Date: November 16, 2009
Creator: Meezan, N B; Atherton, L J; Callahan, D A; Dewald, E L; Dixit, S N; Dzenitis, E G et al.
System: The UNT Digital Library
A Modern Interpretation of the Barney Diagram for Aluminum Solubility in Tank Waste (open access)

A Modern Interpretation of the Barney Diagram for Aluminum Solubility in Tank Waste

Experimental and modeling studies of aluminum solubility in Hanford tank waste have been developed and refined for many years in efforts to resolve new issues or develop waste treatment flowsheets. The earliest of these studies was conducted by G. Scott Barney, who performed solubility studies in highly concentrated electrolyte solutions to support evaporator campaign flowsheets in the 1970's. The 'Barney Diagram', a term still widely used at Hanford today, suggested gibbsite ({gamma}-Al(OH){sub 3}) was much more soluble in tank waste than in simple sodium hydroxide solutions. These results, which were highly surprising at the time, continue to be applied to new situations where aluminum solubility in tank waste is of interest. Here, we review the history and provide a modern explanation for the large gibbsite solubility observed by Barney, an explanation based on basic research that has been performed and published in the last 30 years. This explanation has both thermodynamic and kinetic aspects. Thermodynamically, saturated salt solutions stabilize soluble aluminate species that are minor components in simple sodium hydroxide solutions. These species are the aluminate dimer and the sodium-aluminate ion-pair. Ion-pairs must be present in the Barney simulants because calculations showed that there was insufficient space between the highly …
Date: December 16, 2009
Creator: Reynolds, J. G. & Reynolds, D. A.
System: The UNT Digital Library
Understanding the mechanism of base development of HSQ (open access)

Understanding the mechanism of base development of HSQ

We study the dissolution mechanism of HSQ (hydrogen silsesquioxane) in base solutions with the addition of chloride salts to elucidate the development mechanism. Reaction mechanisms are proposed based on the dissolution mechanism of quartz. Development kinetics points to two dose-dependent development mechanisms. Considering ion sizes, both hydrated and non-hydrated, and ion exchange, we propose that a combination of a surface dominated reaction at higher doses and a matrix dominated reaction at lower doses accounts for the high development contrast with a NaOH base/NaCl salt mixture. The interplay between the hydrated and non-hydrated ion size leads to higher contrast developers, such as tetramethyl ammonium hydroxide (TMAH) with NaCl.
Date: June 16, 2009
Creator: Kim, Jihoon; Chao, Weilun; Griedel, Brian; Liang, Xiaogan; Lewis, Mark; Hilken, Dawn et al.
System: The UNT Digital Library
Microscopic Characterization of Carbonaceous Aerosol Particle Aging in the Outflow from Mexico City (open access)

Microscopic Characterization of Carbonaceous Aerosol Particle Aging in the Outflow from Mexico City

This study was part of the Megacities Initiative: Local and Global Research Observations (MILAGRO) field campaign conducted in Mexico City Metropolitan Area during spring 2006. The physical and chemical transformations of particles aged in the outflow from Mexico City were investigated for the transport event of 22 March 2006. A detailed chemical analysis of individual particles was performed using a combination of complementary microscopy and micro-spectroscopy techniques. The applied techniques included scanning transmission X-ray microscopy (STXM) coupled with near edge X-ray absorption fine structure spectroscopy (NEXAFS) and computer controlled scanning electron microscopy with an energy dispersive X-ray analyzer (CCSEM/EDX). As the aerosol plume evolves from the city center, the organic mass per particle increases and the fraction of carbon-carbon double bonds (associated with elemental carbon) decreases. Organic functional groups enhanced with particle age include: carboxylic acids, alkyl groups, and oxygen bonded alkyl groups. At the city center (T0) the most prevalent aerosol type contained inorganic species (composed of sulfur, nitrogen, oxygen, and potassium) coated with organic material. At the T1 and T2 sites, located northeast of T0 (~;;29 km and ~;;65 km, respectively), the fraction of homogenously mixed organic particles increased in both size and number. These observations illustrate the …
Date: September 16, 2009
Creator: Moffet, R. C.; Henn, T. R.; Tivanski, A. V.; Hopkins, R. J.; Desyaterik, Y.; Kilcoyne, A. L. D. et al.
System: The UNT Digital Library