Response to: “Long-term effectiveness and consequences of carbon dioxide sequestration” by Gary Shaffer, published in Nature Geosciences, 27 June 2010. (open access)

Response to: “Long-term effectiveness and consequences of carbon dioxide sequestration” by Gary Shaffer, published in Nature Geosciences, 27 June 2010.

Shaffer’s (2010) article reports on the long term impact of less than perfect retention of anthropogenic CO2 stored in deep geologic reservoirs and in the ocean. The central thesis of this article is predicated on two deeply flawed assumptions. The first and most glaring is the implicit assumption that society has only one means of reducing greenhouse gas emissions, carbon dioxide capture and storage (CCS). Secondly, there is absolutely no geophysical nor geomechanical basis for assuming an exponential decay of CO2 stored in deep geologic formations as done by Schaffer. Shaffer’s analysis of the impact of leakage from anthropogenic CO2 stored in deep geologic reservoirs are based upon two fundamentally flawed assumptions and therefore the reported results as well as the public policy conclusions presented in the paper need to be read with this understanding in mind as far less CO2 stored below ground because society drew upon a broad portfolio of advanced energy technologies over the coming century coupled with a more technically accurate conceptualization of CO2 storage in the deep subsurface and the important role of secondary and tertiary trapping mechanisms would have yield a far less pessimistic view of the potential role that CCS can play in …
Date: July 12, 2010
Creator: Dooley, James J.
Object Type: Report
System: The UNT Digital Library
Development of stripper options for FRIB (open access)

Development of stripper options for FRIB

The US Department of Energy Facility for Rare Isotope Beams (FRIB) at Michigan State University includes a heavy ion superconducting linac capable of accelerating all ions up to uranium with energies higher than 200 MeV/u and beam power up to 400 kW. To achieve these goals with present ion source performance it is necessary to accelerate simultaneously two charge states of uranium from the ion source in the first section of the linac. At an energy of approximately 16.5 MeV/u it is planned to strip the uranium beam to reduce the voltage needed in the rest of the linac to achieve the final energy. Up to five different charge states are planned to be accelerated simultaneously after the stripper. The design of the stripper is a challenging problem due to the high power deposited (approximately 0.7 kW) in the stripper media by the beam in a small spot. To assure success of the project we have established a research and development program that includes several options: carbon or diamond foils, liquid lithium films, gas strippers and plasma strippers. We present in this paper the status of the different options.
Date: September 12, 2010
Creator: Marti, F.; Hershcovitch, A.; Momozaki, Y.; Nolen, J.; Reed, C. & Thieberger, P.
Object Type: Article
System: The UNT Digital Library
Ergonomics in the Biosciences (open access)

Ergonomics in the Biosciences

None
Date: April 12, 2010
Creator: Alexandre, Melanie
Object Type: Report
System: The UNT Digital Library
Methods for Analyzing Electric Load Shape and its Variability (open access)

Methods for Analyzing Electric Load Shape and its Variability

Current methods of summarizing and analyzing electric load shape are discussed briefly and compared. Simple rules of thumb for graphical display of load shapes are suggested. We propose a set of parameters that quantitatively describe the load shape in many buildings. Using the example of a linear regression model to predict load shape from time and temperature, we show how quantities such as the load?s sensitivity to outdoor temperature, and the effectiveness of demand response (DR), can be quantified. Examples are presented using real building data.
Date: May 12, 2010
Creator: Price, Philip
Object Type: Report
System: The UNT Digital Library
Atmospheric Effects on the Performance of Cdznte Single Crystal Detectors (open access)

Atmospheric Effects on the Performance of Cdznte Single Crystal Detectors

The production of high-quality ternary single-crystal materials for radiation detectors has progressed over the past 15 years. One of the more common materials being studied is CdZnTe (CZT), which can be grown using several methods to produce detector-grade materials. The work presented herein examines the effects of environmental conditions including temperature and humidity on detector performance [full-width at half-maximum (FWHM)] using the single pixel with guard detector configuration. The effects of electrical probe placement, reproducibility, and aging are also presented.
Date: May 12, 2010
Creator: Washington, A.; Duff, M. & Teague, L.
Object Type: Article
System: The UNT Digital Library
Waveguide-Based Ultrasonic and Far-Field Electromagnetic Sensors for Downhole Reservoir Characterization. (open access)

Waveguide-Based Ultrasonic and Far-Field Electromagnetic Sensors for Downhole Reservoir Characterization.

This report summarizes the first year research and development effort leading to development of high-temperature sensors for enhanced geothermal systems. It covers evaluation of ultrasonic and electromagnetic (EM) techniques applied to temperature measurement and flow characterization. On temperature measurement, we have evaluated both microwave radiometry and ultrasonic techniques for temperature gradient and profile measurements. Different antenna designs are evaluated and array loop antenna design is selected for further development. We have also evaluated ultrasonic techniques for total flow characterization, which includes using speed of sound to determine flow temperature, measuring acoustic impedance to estimate fluid density, and using cross-correlation technique to determine the mass flow rate. Method to estimate the flow enthalpy is briefly discussed. At end, the need and proposed techniques to characterize the porosity and permeability of a hot dry rock resource are presented.
Date: November 12, 2010
Creator: Sheen, S. H.; Chien, H. T.; Wang, K.; Liao, S.; Gopalsami, N.; Bakhtiari, S. et al.
Object Type: Report
System: The UNT Digital Library
Structural Integrity Program for the 300,000-Gallon Radioactive Liquid Waste Storage Tanks at the Idaho Nuclear Technology and Engineering Center (open access)

Structural Integrity Program for the 300,000-Gallon Radioactive Liquid Waste Storage Tanks at the Idaho Nuclear Technology and Engineering Center

This report provides a record of the Structural Integrity Program for the 300,000-gal liquid waste storage tanks and associated equipment at the Idaho Nuclear Technology and Engineering Center, as required by U.S. Department of Energy M 435.1-1, “Radioactive Waste Management Manual.” This equipment is known collectively as the Tank Farm Facility. This report is an update, and replaces the previous report by the same title issued April 2003. The conclusion of this report is that the Tank Farm Facility tanks, vaults, and transfer systems that remain in service for storage are structurally adequate, and are expected to remain structurally adequate over the remainder of their planned service life through 2012. Recommendations are provided for continued monitoring of the Tank Farm Facility.
Date: August 12, 2010
Creator: Bryant, Jeffrey W.
Object Type: Report
System: The UNT Digital Library
Waste Treatment Plant Support Program: Summaries of Reports Produced During Fiscal Years 1999-2010 (open access)

Waste Treatment Plant Support Program: Summaries of Reports Produced During Fiscal Years 1999-2010

The Waste Treatment Plant (WTP) being built on the U.S. Department of Energy (DOE) Hanford Site will be the largest chemical processing plant in the United States. Bechtel National Inc. (BNI) is the designer and constructor for the WTP. The Pacific Northwest National Laboratory (PNNL) has provided significant research and testing support to the WTP. This report provides a summary of reports developed initially under PNNL’s “1831” use agreement and later PNNL’s “1830” prime contract with DOE in support of the WTP. In March 2001, PNNL under its “1831” use agreement entered into a contract with BNI to support their research and testing activities. However, PNNL support to the WTP predates BNI involvement. Prior to March 2001, PNNL supported British Nuclear Fuels Ltd. in its role as overall designer and constructor. In February 2007, execution of PNNL’s support to the WTP was moved under its “1830” prime contract with DOE. Documents numbered “PNWD-XXXX” were issued under PNNL’s “1831” use agreement. Documents numbered “PNNL-XXXX” were issued under PNNL’s “1830” prime contract with DOE. The documents are sorted by fiscal year and categorized as follows:  Characterization  HLW (High Level Waste)  Material Characterization  Pretreatment  Simulant Development  Vitrification …
Date: August 12, 2010
Creator: Beeman, Gordon H.
Object Type: Report
System: The UNT Digital Library
Particle removal challenges with EUV patterned mask for the sub-22nm HP node (open access)

Particle removal challenges with EUV patterned mask for the sub-22nm HP node

The particle removal efficiency (PRE) of cleaning processes diminishes whenever the minimum defect size for a specific technology node becomes smaller. For the sub-22 nm half-pitch (HP) node, it was demonstrated that exposure to high power megasonic up to 200 W/cm{sup 2} did not damage 60 nm wide TaBN absorber lines corresponding to the 16 nm HP node on wafer. An ammonium hydroxide mixture and megasonics removes {ge}50 nm SiO{sub 2} particles with a very high PRE, A sulfuric acid hydrogen peroxide mixture (SPM) in addition to ammonium hydroxide mixture (APM) and megasonic is required to remove {ge}28 nm SiO{sub 2} particles with a high PRE. Time-of-flight secondary ion mass spectroscopy (TOFSIMS) studies show that the presence of O{sub 2} during a vacuum ultraviolet (VUV) ({lambda} = 172 nm) surface conditioning step will result in both surface oxidation and Ru removal, which drastically reduce extreme ultraviolet (EUV) mask life time under multiple cleanings. New EUV mask cleaning processes show negligible or no EUV reflectivity loss and no increase in surface roughness after up to 15 cleaning cycles. Reviewing of defect with a high current density scanning electron microscope (SEM) drastically reduces PRE and deforms SiO{sub 2} particles. 28 nm SiO{sub …
Date: March 12, 2010
Creator: Rastegar, A.; Eichenlaub, S.; Kadaksham, A. J.; Lee, B.; House, M.; Huh, S. et al.
Object Type: Article
System: The UNT Digital Library
Photon flux requirements for EUV reticle imaging microscopy in the 22 and 16 nm nodes (open access)

Photon flux requirements for EUV reticle imaging microscopy in the 22 and 16 nm nodes

EUV-wavelength actinic microscopy yields detailed information about EUV mask patterns, architectures, defects, and the performance of defect repair strategies, without the complications of photoresist imaging. The measured aerial image intensity profiles provide valuable feedback to improve mask and lithography system modeling methods. In order to understand the photon-flux-dependent pattern measurement limits of EUV mask-imaging microscopy, we have investigated the effects of shot noise on aerial image linewidth measurements for lines in the 22 and 16-nm generations. Using a simple model of image formation near the resolution limit, we probe the influence of photon shot noise on the measured, apparent line roughness. With this methodology, we arrive at general flux density requirements independent of the specific EUV microscope configurations. Analytical and statistical analysis of aerial image simulations in the 22 and 16-nm generations reveal the trade-offs between photon energy density (controllable with exposure time), effective pixel dimension on the CCO (controlled by the microscope's magnification ratio), and image log slope (ILS). We find that shot-noise-induced linewidth roughness (LWR) varies imersely with the square root of the photon energy density, and is proportional to the imaging magnification ratio. While high magnification is necessary for adequate spatial resolution, for a given flux density, …
Date: March 12, 2010
Creator: Wintz, D.; Goldberg, K. A.; Mochi, I. & Huh, S.
Object Type: Article
System: The UNT Digital Library
Hydrogeologic Evaluation of a Ground-Source Cooling System at the BSF/CSF on the Battelle Campus: Final Report (open access)

Hydrogeologic Evaluation of a Ground-Source Cooling System at the BSF/CSF on the Battelle Campus: Final Report

This report documents both the field characterization activities and the numerical modeling effort at the BSF/CSF site to determine the viability of an open-loop ground source heat pump (GSHP). The primary purpose of the integrated field and modeling study was to determine far-field impacts related to a non-consumptive use water right for the well field containing four extraction and four injection wells. In the field, boreholes were logged and used to develop the geologic conceptual model. Hydraulic testing was performed to identify hydraulic properties and determine sustainable pumping rates. Estimates of the Ringold hydraulic conductivity (60-150 m/d) at the BSF/CSF site were consistent with the local and regional hydrogeology as well as estimates previously published by other investigators. Sustainable pumping rates at the extraction wells were variable (100 – 700 gpm), and confirmed field observations of aquifer heterogeneity. Field data were used to develop a numerical model of the site. Simulations assessed the potential of the well field to impact nearby contaminant plumes, neighboring water rights, and the thermal regime of nearby surface water bodies. Using steady-state flow scenarios in conjunction with particle tracking, a radius of influence of 400–600 m was identified around the well field. This distance was …
Date: May 12, 2010
Creator: Freedman, Vicky L.; Mackley, Rob D.; Waichler, Scott R.; Horner, Jacob A.; Moon, Thomas W.; Newcomer, Darrell R. et al.
Object Type: Report
System: The UNT Digital Library
A new medium energy beam transport line for the proton injector of AGS-RHIC (open access)

A new medium energy beam transport line for the proton injector of AGS-RHIC

In Brookhaven National Laboratory (BNL), a 750 keV medium energy beam transport line between the 201 MHz 750 keV proton RFQ and the 200 MeV Alvarez DTL is being modified to get a better transmission of the beam. Within a tight space, high field gradient quadrupoles (65 Tm) and newly designed steering magnets (6.5 mm in length) will be installed considering the cross-talk effects. Also a new half wave length 200 MHz buncher is being prepared. The beam commissioning will be done in this year. To enhance the performance of the proton linacs, the MEBT is being modified. New quadrupole magnets, steering magnets and a half wave length buncher as shown in Figure 7 will be installed and be commissioned soon.
Date: September 12, 2010
Creator: Okamura, M.; Briscoe, B.; Fite, J.; LoDestro, V.; Raparia, D.; Ritter, J. et al.
Object Type: Article
System: The UNT Digital Library
A Comprehensive Analysis of Uncertainties Affecting the Stellar Mass-Halo Mass Relation for 0<z<4 (open access)

A Comprehensive Analysis of Uncertainties Affecting the Stellar Mass-Halo Mass Relation for 0<z<4

We conduct a comprehensive analysis of the relationship between central galaxies and their host dark matter halos, as characterized by the stellar mass - halo mass (SM-HM) relation, with rigorous consideration of uncertainties. Our analysis focuses on results from the abundance matching technique, which assumes that every dark matter halo or subhalo above a specific mass threshold hosts one galaxy. We provide a robust estimate of the SM-HM relation for 0 &lt; z &lt; 1 and discuss the quantitative effects of uncertainties in observed galaxy stellar mass functions (GSMFs) (including stellar mass estimates and counting uncertainties), halo mass functions (including cosmology and uncertainties from substructure), and the abundance matching technique used to link galaxies to halos (including scatter in this connection). Our analysis results in a robust estimate of the SM-HM relation and its evolution from z=0 to z=4. The shape and evolution are well constrained for z &lt; 1. The largest uncertainties at these redshifts are due to stellar mass estimates (0.25 dex uncertainty in normalization); however, failure to account for scatter in stellar masses at fixed halo mass can lead to errors of similar magnitude in the SM-HM relation for central galaxies in massive halos. We also investigate …
Date: May 12, 2010
Creator: Behroozi, Peter S.; Conroy, Charlie & Wechsler, Risa H.
Object Type: Article
System: The UNT Digital Library
A study of defects on EUV mask using blank inspection, patterned mask inspection, and wafer inspection (open access)

A study of defects on EUV mask using blank inspection, patterned mask inspection, and wafer inspection

The availability of defect-free masks remains one of the key challenges for inserting extreme ultraviolet lithography (EUVL) into high volume manufacturing. yet link data is available for understanding native defects on real masks. In this paper, a full-field EUV mask is fabricated to investigate the printability of various defects on the mask. The printability of defects and identification of their source from mask fabrication to handling were studied using wafer inspection. The printable blank defect density excluding particles and patterns is 0.63 cm{sup 2}. Mask inspection is shown to have better sensitivity than wafer inspection. The sensitivity of wafer inspection must be improved using through-focus analysis and a different wafer stack.
Date: March 12, 2010
Creator: Huh, S.; Ren, L.; Chan, D.; Wurm, S.; Goldberg, K. A.; Mochi, I. et al.
Object Type: Article
System: The UNT Digital Library
RACORO Data Guide (open access)

RACORO Data Guide

This document provides an overview to the five-month RACORO Campaign. There are many details in such an extensive program that this document cannot capture; therefore, it should be thought of as a guide for acquainting yourself with the program and you are encouraged to contact the members involved. In particular, users of the data are strongly urged to contact instrument principal investigators (PIs) about use of the data. Further, it is highly recommended that studies using the data be done in collaboration with the instrument PIs, since they are in the best position to provide insights and or caveats associated with the data that should be considered.
Date: October 12, 2010
Creator: Vogelmann, A.
Object Type: Report
System: The UNT Digital Library
Peroxide Destruction Testing for the 200 Area Effluent Treatment Facility (open access)

Peroxide Destruction Testing for the 200 Area Effluent Treatment Facility

The hydrogen peroxide decomposer columns at the 200 Area Effluent Treatment Facility (ETF) have been taken out of service due to ongoing problems with particulate fines and poor destruction performance from the granular activated carbon (GAC) used in the columns. An alternative search was initiated and led to bench scale testing and then pilot scale testing. Based on the bench scale testing three manganese dioxide based catalysts were evaluated in the peroxide destruction pilot column installed at the 300 Area Treated Effluent Disposal Facility. The ten inch diameter, nine foot tall, clear polyvinyl chloride (PVC) column allowed for the same six foot catalyst bed depth as is in the existing ETF system. The flow rate to the column was controlled to evaluate the performance at the same superficial velocity (gpm/ft{sup 2}) as the full scale design flow and normal process flow. Each catalyst was evaluated on peroxide destruction performance and particulate fines capacity and carryover. Peroxide destruction was measured by hydrogen peroxide concentration analysis of samples taken before and after the column. The presence of fines in the column headspace and the discharge from carryover was generally assessed by visual observation. All three catalysts met the peroxide destruction criteria by …
Date: March 12, 2010
Creator: Halgren, D. L.
Object Type: Report
System: The UNT Digital Library
Printability and inspectability of programmed pit defects on teh masks in EUV lithography (open access)

Printability and inspectability of programmed pit defects on teh masks in EUV lithography

Printability and inspectability of phase defects in ELlVL mask originated from substrate pit were investigated. For this purpose, PDMs with programmed pits on substrate were fabricated using different ML sources from several suppliers. Simulations with 32-nm HP L/S show that substrate pits with below {approx}20 nm in depth would not be printed on the wafer if they could be smoothed by ML process down to {approx}1 nm in depth on ML surface. Through the investigation of inspectability for programmed pits, minimum pit sizes detected by KLA6xx, AIT, and M7360 depend on ML smoothing performance. Furthermore, printability results for pit defects also correlate with smoothed pit sizes. AIT results for pattemed mask with 32-nm HP L/S represents that minimum printable size of pits could be {approx}28.3 nm of SEVD. In addition, printability of pits became more printable as defocus moves to (-) directions. Consequently, printability of phase defects strongly depends on their locations with respect to those of absorber patterns. This indicates that defect compensation by pattern shift could be a key technique to realize zero printable phase defects in EUVL masks.
Date: March 12, 2010
Creator: Kang, I. Y.; Seo, H. S.; Ahn, B. S.; Lee, D. G.; Kim, D.; Huh, S. et al.
Object Type: Article
System: The UNT Digital Library
Energy-Consumption and Carbon-Emission Analysis of Vehicle and Component Manufacturing. (open access)

Energy-Consumption and Carbon-Emission Analysis of Vehicle and Component Manufacturing.

A model is presented for calculating the environmental burdens of the part manufacturing and vehicle assembly (VMA) stage of the vehicle life cycle. The approach is bottom-up, with a special focus on energy consumption and CO{sub 2} emissions. The model is applied to both conventional and advanced vehicles, the latter of which include aluminum-intensive, hybrid electric, plug-in hybrid electric and all-electric vehicles. An important component of the model, a weight-based distribution function of materials and associated transformation processes (casting, stamping, etc.), is developed from the United States Council for Automotive Research Generic Vehicle Life Cycle Inventory Study. As the approach is bottom-up, numerous transformation process data and plant operational data were extracted from the literature for use in representing the many operations included in the model. When the model was applied to conventional vehicles, reliable estimates of cumulative energy consumption (34 GJ/vehicle) and CO{sub 2} emission (2 tonnes/vehicle) were computed for the VMA life-cycle stage. The numerous data sets taken from the literature permitted the development of some statistics on model results. Because the model explicitly includes a greater coverage of relevant manufacturing processes than many earlier studies, our energy estimates are on the higher end of previously published values. …
Date: October 12, 2010
Creator: Sullivan, J. L.; Burnham, A.; Wang, M. & Systems, Energy
Object Type: Report
System: The UNT Digital Library
Radiative forcing and temperature response to changes in urban albedos and associated CO2 offsets (open access)

Radiative forcing and temperature response to changes in urban albedos and associated CO2 offsets

The two main forcings that can counteract to some extent the positive forcings from greenhouse gases from pre-industrial times to present-day are the aerosol and related aerosol-cloud forcings, and the radiative response to changes in surface albedo. Here, we quantify the change in radiative forcing and land surface temperature that may be obtained by increasing the albedos of roofs and pavements in urban areas in temperate and tropical regions of the globe by 0.1. Using the catchment land surface model (the land model coupled to the GEOS-5 Atmospheric General Circulation Model), we quantify the change in the total outgoing (outgoing shortwave+longwave) radiation and land surface temperature to a 0.1 increase in urban albedos for all global land areas. The global average increase in the total outgoing radiation was 0.5 Wm{sup -2}, and temperature decreased by {approx}0.008 K for an average 0.003 increase in surface albedo. These averages represent all global land areas where data were available from the land surface model used and are for the boreal summer (June-July-August). For the continental U.S. the total outgoing radiation increased by 2.3 Wm{sup -2}, and land surface temperature decreased by {approx}0.03 K for an average 0.01 increase in surface albedo. Based on …
Date: February 12, 2010
Creator: Menon, Surabi; Akbari, Hashem; Mahanama, Sarith; Sednev, Igor & Levinson, Ronnen
Object Type: Article
System: The UNT Digital Library
EUV pattern defect detection sensitivity based on aerial image linewidth measurements (open access)

EUV pattern defect detection sensitivity based on aerial image linewidth measurements

As the quality of EUV-wavelength mask inspection microscopes improves over time, the image properties and intensity profiles of reflected light can be evaluated in ever-greater detail. The SEMATECH Berkeley Actinic Inspection Tool (AIT) is one such microscope, featuring mask resolution values that match or exceed those available through lithographic printing in current photoresists. In order to evaluate the defect detection sensitivity of the AIT for dense line patterns on typical masks, the authors study the line width roughness (LWR) on two masks, as measured in the EUV images. They report the through-focus and pitch dependence of contrast, image log slope, linewidth, and LWR. The AIT currently reaches LWR 3{sigma} values close to 9 nm for 175 nm half-pitch lines. This value is below 10% linewidth for nearly all lines routinely measured in the AIT. Evidence suggests that this lower level may arise from the mask's inherent pattern roughness. While the sensitivity limit of the AlT has not yet been established, it is clear that the AIT has the required sensitivity to detect defects that cause 10% linewidth changes in line sizes of 125 nm and larger.
Date: February 12, 2010
Creator: Goldberg, K. A.; Mochi, I.; Naulleau, P.; Liang, T.; Yan, P.-Y. & Huh, S.
Object Type: Article
System: The UNT Digital Library
Actinic imaging of native and programmed defects on a full-field mask (open access)

Actinic imaging of native and programmed defects on a full-field mask

We describe the imaging and characterization of native defects on a full field extreme ultraviolet (EUV) mask, using several reticle and wafer inspection modes. Mask defect images recorded with the SEMA TECH Berkeley Actinic Inspection Tool (AIT), an EUV-wavelength (13.4 nm) actinic microscope, are compared with mask and printed-wafer images collected with scanning electron microscopy (SEM) and deep ultraviolet (DUV) inspection tools. We observed that defects that appear to be opaque in the SEM can be highly transparent to EUV light, and inversely, defects that are mostly transparent to the SEM can be highly opaque to EUV. The nature and composition of these defects, whether they appear on the top surface, within the multilayer coating, or on the substrate as buried bumps or pits, influences both their significance when printed, and their detectability with the available techniques. Actinic inspection quantitatively predicts the characteristics of printed defect images in ways that may not be possible with non-EUV techniques. As a quantitative example, we investigate the main structural characteristics of a buried pit defect based on EUV through-focus imaging.
Date: March 12, 2010
Creator: Mochi, I.; Goldberg, K. A.; Fontaine, B. La; Tchikoulaeva, A. & Holfeld, C.
Object Type: Article
System: The UNT Digital Library
Radiochemical tracers as a mix diagnostic for the ignition double-shell capsule (open access)

Radiochemical tracers as a mix diagnostic for the ignition double-shell capsule

One of the most important challenges confronting laser-driven capsule implosion experiments will be a quantitative evaluation of the implosion dynamics. Since these experiments will encounter extreme conditions of pressure and temperature, establishing robust, sensitive diagnostics will be difficult. Radiochemical signatures provide insight into material mixing and laser drive asymmetry and complement x-ray and other nuclear diagnostics, since the relevant nuclear reactions sample core implosion conditions directly. Simulations of an ignition double shell target indicate that several experimentally accessible isomeric ratios will be suitable monitors of mix.
Date: May 12, 2010
Creator: Colvin, J; Cerjan, C; Hoffman, R; Stoyer, M A & Amendt, P
Object Type: Article
System: The UNT Digital Library
Measured Black Carbon Deposition on the Sierra Nevada Snow Pack and Implication for Snow Pack Retreat (open access)

Measured Black Carbon Deposition on the Sierra Nevada Snow Pack and Implication for Snow Pack Retreat

Modeling studies show that the darkening of snow and ice by black carbon deposition is a major factor for the rapid disappearance of arctic sea ice, mountain glaciers and snow packs. This study provides one of the first direct measurements for the efficient removal of black carbon from the atmosphere by snow and its subsequent deposition to the snow packs of California. The early melting of the snow packs in the Sierras is one of the contributing factors to the severe water problems in California. BC concentrations in falling snow were measured at two mountain locations and in rain at a coastal site. All three stations reveal large BC concentrations in precipitation, ranging from 1.7 ng/g to 12.9 ng/g. The BC concentrations in the air after the snow fall were negligible suggesting an extremely efficient removal of BC by snow. The data suggest that below cloud scavenging, rather than ice nuclei, was the dominant source of BC in the snow. A five-year comparison of BC, dust, and total fine aerosol mass concentrations at multiple sites reveals that the measurements made at the sampling sites were representative of large scale deposition in the Sierra Nevada. The relative concentration of iron and …
Date: January 12, 2010
Creator: Hadley, Odelle L.; C.E., Corrigan; T. W., Kirchstetter; Cliff, S. S. & Ramanathan, V.
Object Type: Article
System: The UNT Digital Library
INNOVATIVE ALARA TOOLS AND WORK PRACTICES USED AT THE DOE HANFORD SITE (open access)

INNOVATIVE ALARA TOOLS AND WORK PRACTICES USED AT THE DOE HANFORD SITE

The Hanford Nuclear Reservation occupies an area of 586 square miles in southeastern Washington state. The site was created as part of the World War II Manhattan Project to produce weapons grade plutonium. A multitude of old reactor plants, processing facilities, underground tank farms, contaminated soil and ground water remain and are part of an on-going environmental cleanup mission of the site. The Columbia River bisects Hanford, and the concern is that the river will become contaminated if the sources of contamination are not removed. Currently facilities are being removed, the ground water is being treated, and contaminated soil is being transferred to an approved burial ground about 15 miles away from the River located in the center of the Hanford Site The remaining facilities and adjacent structures are undergoing D&amp;D (decontaminate and demolish) and to date, significant progress has been made. During this presentation, I will discuss how we are using innovative tools and work practices to D&amp;D these Hanford Site facilities.
Date: February 12, 2010
Creator: LO, WAGGONER
Object Type: Article
System: The UNT Digital Library