THE SENSITIVITY OF CARBON STEELS' SUSCEPTIBILITY TO LOCALIZED CORROSION TO THE PH OF NITRATE BASED NUCLEAR WASTES (open access)

THE SENSITIVITY OF CARBON STEELS' SUSCEPTIBILITY TO LOCALIZED CORROSION TO THE PH OF NITRATE BASED NUCLEAR WASTES

The Hanford tank reservation contains approximately 50 million gallons of liquid legacy radioactive waste from cold war weapons production, which is stored in 177 underground storage tanks. The tanks will be in use until waste processing operations are completed. The wastes tend to be high pH (over 10) and nitrate based. Under these alkaline conditions carbon steels tend to be passive and undergo relatively slow uniform corrosion. However, the presence of nitrate and other aggressive species, can lead to pitting and stress corrosion cracking. This work is a continuation of previous work that investigated the propensity of steels to suffer pitting and stress corrosion cracking in various waste simulants. The focus of this work is an investigation of the sensitivity of the steels' pitting and stress corrosion cracking susceptibility tosimulant pH. Previous work demonstrated that wastes that are high in aggressive nitrate and low in inhibitory nitrite are susceptible to localized corrosion. However, the previous work involved wastes with pH 12 or higher. The current work involves wastes with lower pH of 10 or 11. It is expected that at these lower pHs that a higher nitrite-to-nitrate ratio will be necessary to ensure tank integrity. This experimental work involved both …
Date: January 14, 2010
Creator: KD, BOOMER
System: The UNT Digital Library
PERFORMANCE ASSESSMENT TO SUPPORT CLOSURE OF SINGLE-SHELL TANK WASTE MANAGEMENT AREA C AT THE HANFORD SITE (open access)

PERFORMANCE ASSESSMENT TO SUPPORT CLOSURE OF SINGLE-SHELL TANK WASTE MANAGEMENT AREA C AT THE HANFORD SITE

Current proposed regulatory agreements (Consent Decree) at the Hanford Site call for closure of the Single-Shell Tank (SST) Waste Management Area (WMA) C in the year 2019. WMA C is part of the SST system in 200 East area ofthe Hanford Site and is one of the first tank farm areas built in mid-1940s. In order to close WMA C, both tank and facility closure activities and corrective actions associated with existing soil and groundwater contamination must be performed. Remedial activities for WMA C and corrective actions for soils and groundwater within that system will be supported by various types of risk assessments and interim performance assessments (PA). The U.S. Department of Energy, Office of River Protection (DOE-ORP) and the State ofWashington Department of Ecology (Ecology) are sponsoring a series of working sessions with regulators and stakeholders to solicit input and to obtain a common understanding concerning the scope, methods, and data to be used in the planned risk assessments and PAs to support closure of WMA C. In addition to DOE-ORP and Ecology staff and contractors, working session members include representatives from the U.S. Enviromnental Protection Agency, the U.S. Nuclear Regulatory Commission (NRC), interested tribal nations, other stakeholders groups, …
Date: January 14, 2010
Creator: MP, BERGERON
System: The UNT Digital Library
RESORCINOL-FORMALDEHYDE ION EXCHANGE RESIN CHEMISTRY FOR HIGH LEVEL WASTE TREATMENT (open access)

RESORCINOL-FORMALDEHYDE ION EXCHANGE RESIN CHEMISTRY FOR HIGH LEVEL WASTE TREATMENT

A principal goal at the Savannah River Site is to safely dispose of the large volume of liquid nuclear waste held in many storage tanks. In-tank ion exchange technology is being considered for cesium removal using a polymer resin made of resorcinol formaldehyde that has been engineered into microspheres. The waste under study is generally lower in potassium and organic components than Hanford waste; therefore, the resin performance was evaluated with actual dissolved salt waste. The ion exchange performance and resin chemistry results are discussed.
Date: January 14, 2010
Creator: Nash, C. & Duignan, M.
System: The UNT Digital Library
Charm Physics at BaBar and Belle (open access)

Charm Physics at BaBar and Belle

Abstract: Recent results on charm physics from Belle and BaBar are reported. These include studies of charm mixing, CP violation in the charm sector and properties of charmed meson decay. Measurements of the Ds pseudoscalar purely leptonic decay branching fractions are also reported, which allow for experimental comparisons with the lattice calculation of the ƒDs decay constant.
Date: June 14, 2013
Creator: Milanés, Diego
System: The UNT Digital Library
THE ROLE OF LAND USE IN ENVIRONMENTAL DECISION MAKING AT THREE DOE MEGA-CLEANUP SITES FERNALD & ROCKY FLATS & MOUND (open access)

THE ROLE OF LAND USE IN ENVIRONMENTAL DECISION MAKING AT THREE DOE MEGA-CLEANUP SITES FERNALD & ROCKY FLATS & MOUND

This paper explores the role that future land use decisions have played in the establishment of cost-effective cleanup objectives and the setting of environmental media cleanup levels for the three major U.S. Department of Energy (DOE) sites for which cleanup has now been successfully completed: the Rocky Flats, Mound, and Fernald Closure Sites. At each site, there are distinct consensus-building histories throughout the following four phases: (1) the facility shut-down and site investigation phase, which took place at the completion of their Cold War nuclear-material production missions; (2) the decision-making phase, whereby stakeholder and regulatory-agency consensus was achieved for the future land-use-based environmental decisions confronting the sites; (3) the remedy selection phase, whereby appropriate remedial actions were identified to achieve the future land-use-based decisions; and (4) the implementation phase, whereby the selected remedial actions for these high-profile sites were implemented and successfully closed out. At each of the three projects, there were strained relationships and distrust between the local community and the DOE as a result of site contamination and potential health effects to the workers and local residents. To engage citizens and interested stakeholder groups - particularly in the role of final land use in the decision-making process, the …
Date: January 14, 2011
Creator: MA, JEWETT
System: The UNT Digital Library
Pulsed-beam measurement of defect diffusion lengths in ion-bombarded solids (open access)

Pulsed-beam measurement of defect diffusion lengths in ion-bombarded solids

None
Date: June 14, 2012
Creator: Charnvanichborikarn, S; Myers, M T; Shao, L & Kucheyev, S O
System: The UNT Digital Library
Heavy Quarkonium and Quarkonium-Like States at Belle and BaBar (open access)

Heavy Quarkonium and Quarkonium-Like States at Belle and BaBar

None
Date: June 14, 2013
Creator: Kuzmin, A.
System: The UNT Digital Library
An Experimental and Theoretical Study of Ti-6Al-4V to Multi-mbar Pressures (open access)

An Experimental and Theoretical Study of Ti-6Al-4V to Multi-mbar Pressures

We report results from an experimental and theoretical study of the ternary alloy Ti-6Al-4V to 221 GPa. We observe a phase transition to the hexagonal {omega}-phase at approximately 30 GPa, and then a further transition to the cubic {beta}-phase starting at 94-99 GPa. We do not observe the orthorhombic {gamma} and {delta} phases reported previously in pure Ti. Computational studies show that this sequence is possible only if there is significant local atomic ordering during the compression process, yet insufficient atomic diffusion to reach the phase separated thermodynamic equilibrium state.
Date: March 14, 2012
Creator: MacLeod, S. G.; Tegner, B. E.; Cynn, H.; Evans, W. J.; Proctor, J.; McMahon, M. I. et al.
System: The UNT Digital Library
Measurement of the Top Quark-Pair Production Cross Section With ATLAS in Pp Collisions at $\sqrt{s}=7$ TeV (open access)

Measurement of the Top Quark-Pair Production Cross Section With ATLAS in Pp Collisions at $\sqrt{s}=7$ TeV

None
Date: June 14, 2013
Creator: Aad, Georges
System: The UNT Digital Library
Three-dimensional modeling and analysis of a high energy density Kelvin-Helmholtz experiment (open access)

Three-dimensional modeling and analysis of a high energy density Kelvin-Helmholtz experiment

None
Date: February 14, 2012
Creator: Raman, K. S.; Hurricane, O. A.; Park, H. S.; Remington, B. A.; Robey, H. & Smalyuk, V. A.
System: The UNT Digital Library
RELIABILITY BASED DESIGN OF FIXED FOUNDATION WIND TURBINES (open access)

RELIABILITY BASED DESIGN OF FIXED FOUNDATION WIND TURBINES

Recent analysis of offshore wind turbine foundations using both applicable API and IEC standards show that the total load demand from wind and waves is greatest in wave driven storms. Further, analysis of overturning moment loads (OTM) reveal that impact forces exerted by breaking waves are the largest contributor to OTM in big storms at wind speeds above the operating range of 25 m/s. Currently, no codes or standards for offshore wind power generators have been adopted by the Bureau of Ocean Energy Management Regulation and Enforcement (BOEMRE) for use on the Outer Continental Shelf (OCS). Current design methods based on allowable stress design (ASD) incorporate the uncertainty in the variation of loads transferred to the foundation and geotechnical capacity of the soil and rock to support the loads is incorporated into a factor of safety. Sources of uncertainty include spatial and temporal variation of engineering properties, reliability of property measurements applicability and sufficiency of sampling and testing methods, modeling errors, and variability of estimated load predictions. In ASD these sources of variability are generally given qualitative rather than quantitative consideration. The IEC 61400‐3 design standard for offshore wind turbines is based on ASD methods. Load and resistance factor design …
Date: October 14, 2013
Creator: Nichols, R.
System: The UNT Digital Library
Optics and Emittance Studies Using the ATF2 Multi-OTR System (open access)

Optics and Emittance Studies Using the ATF2 Multi-OTR System

None
Date: October 14, 2013
Creator: Alabau-Gonzalvo, J.; Blanch Gutierrez, C.; Faus-Golfe, A.; Garcia-Garrigos, J. J.; Resta-L?pez, J.; U., /Valencia et al.
System: The UNT Digital Library
Radiative and Leptonic B-meson Decays from the B-factories (open access)

Radiative and Leptonic B-meson Decays from the B-factories

Radiative and leptonic decays of B-mesons represent an excellent laboratory for the search for New Physics. I present here recent results on radiative and leptonic decays from the Belle and BABAR collaborations. Radiative penguin and leptonic B-meson decays are excellent probes for investigating the effects of New Physics. Although current measurements are in agreement with the Standard Model expectations, they are still quite useful for setting bounds on possible NP models. The B {yields} X{sub s}{gamma} and B {yields} {tau}{nu} measurements, for example, put strong constraints on the mass of charged Higgs bosons in Type II two-Higgs double models. The B {yields} X{sub s}{gamma} branching fraction measurements also constrain models with universal extra dimensions.
Date: November 14, 2011
Creator: Walsh, John
System: The UNT Digital Library
Diffusivity of Mixtures in Warm Dense Matter Regime (open access)

Diffusivity of Mixtures in Warm Dense Matter Regime

None
Date: June 14, 2013
Creator: Haxhimali, T. & Rudd, R. E.
System: The UNT Digital Library
Physicochemical controls on absorbed water film thickness in unsaturated geological media (open access)

Physicochemical controls on absorbed water film thickness in unsaturated geological media

Adsorbed water films commonly coat mineral surfaces in unsaturated soils and rocks, reducing flow and transport rates. Therefore, it is important to understand how adsorbed film thickness depends on matric potential, surface chemistry, and solution chemistry. Here, the problem of adsorbed water film thickness is examined through combining capillary scaling with the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Novel aspects of this analysis include determining capillary influences on film thicknesses, and incorporating solution chemistry-dependent electrostatic potential at air-water interfaces. Capillary analysis of monodisperse packings of spherical grains provided estimated ranges of matric potentials where adsorbed films are stable, and showed that pendular rings within drained porous media retain most of the 'residual' water except under very low matric potentials. Within drained pores, capillary contributions to thinning of adsorbed films on spherical grains are shown to be small, such that DLVO calculations for flat surfaces are suitable approximations. Hamaker constants of common soil minerals were obtained to determine ranges of the dispersion component to matric potential-dependent film thickness. The pressure component associated with electrical double layer forces was estimated using the compression and linear superposition approximations. The pH-dependent electrical double layer pressure component is the dominant contribution to film thicknesses at intermediate values of …
Date: June 14, 2011
Creator: Tokunaga, T.
System: The UNT Digital Library
COG - Special Features of Interest to Criticality Safety Practitioners (open access)

COG - Special Features of Interest to Criticality Safety Practitioners

COG is a modern, general-purpose, high fidelity, multi-particle transport code developed at the Lawrence Livermore National Laboratory specifically for use in deep penetration (shielding) and criticality safety calculations. This paper describes some features in COG of special interest to criticality safety practitioners.
Date: January 14, 2010
Creator: Buck, R M; Heinrichs, D P; Krass, A W & Lent, E M
System: The UNT Digital Library
Solid State Marx Modulators for Emerging Applications (open access)

Solid State Marx Modulators for Emerging Applications

Emerging linear accelerator applications increasingly push the boundaries of RF system performance and economics. The power modulator is an integral part of RF systems whose characteristics play a key role in the determining parameters such as efficiency, footprint, cost, stability, and availability. Particularly within the past decade, solid-state switch based modulators have become the standard in high-performance, high power modulators. One topology, the Marx modulator, has characteristics which make it particularly attractive for several emerging applications. This paper is an overview of the Marx topology, some recent developments, and a case study of how this architecture can be applied to a few proposed linear accelerators.
Date: September 14, 2012
Creator: Kemp, M.A.
System: The UNT Digital Library
Magnetorotational Turbulence Transports Angular Momentum in Stratified Disks with Low Magnetic Prandtl Number but Magnetic Reynolds Number above a Critical Value (open access)

Magnetorotational Turbulence Transports Angular Momentum in Stratified Disks with Low Magnetic Prandtl Number but Magnetic Reynolds Number above a Critical Value

The magnetorotational instability (MRI) may dominate outward transport of angular momentum in accretion disks, allowing material to fall onto the central object. Previous work has established that the MRI can drive a mean-field dynamo, possibly leading to a self-sustaining accretion system. Recently, however, simulations of the scaling of the angular momentum transport parameter {alpha}{sub SS} with the magnetic Prandtl number Pm have cast doubt on the ability of the MRI to transport astrophysically relevant amounts of angular momentum in real disk systems. Here, we use simulations including explicit physical viscosity and resistivity to show that when vertical stratification is included, mean field dynamo action operates, driving the system to a configuration in which the magnetic field is not fully helical. This relaxes the constraints on the generated field provided by magnetic helicity conservation, allowing the generation of a mean field on timescales independent of the resistivity. Our models demonstrate the existence of a critical magnetic Reynolds number Rm{sub crit}, below which transport becomes strongly Pm-dependent and chaotic, but above which the transport is steady and Pm-independent. Prior simulations showing Pm-dependence had Rm < Rm{sub crit}. We conjecture that this steady regime is possible because the mean field dynamo is not …
Date: February 14, 2012
Creator: Oishi, Jeffrey S.; /KIPAC, Menlo Park; Low, Mordecai-Mark Mac & Hist., /Amer. Museum Natural
System: The UNT Digital Library
SciDAC Advances in Beam Dynamics Simulation: From Light Sources to Colliders (open access)

SciDAC Advances in Beam Dynamics Simulation: From Light Sources to Colliders

In this paper, we report on progress that has been made in beam dynamics simulation, from light sources to colliders, during the first year of the SciDAC-2 accelerator project 'Community Petascale Project for Accelerator Science and Simulation (ComPASS).' Several parallel computational tools for beam dynamics simulation are described. Also presented are number of applications in current and future accelerator facilities (e.g., LCLS, RHIC, Tevatron, LHC, and ELIC). Particle accelerators are some of most important tools of scientific discovery. They are widely used in high-energy physics, nuclear physics, and other basic and applied sciences to study the interaction of elementary particles, to probe the internal structure of matter, and to generate high-brightness radiation for research in materials science, chemistry, biology, and other fields. Modern accelerators are complex and expensive devices that may be several kilometers long and may consist of thousands of beamline elements. An accelerator may transport trillions of charged particles that interact electromagnetically among themselves, that interact with fields produced by the accelerator components, and that interact with beam-induced fields. Large-scale beam dynamics simulations on massively parallel computers can help provide understanding of these complex physical phenomena, help minimize design cost, and help optimize machine operation. In this paper, …
Date: November 14, 2011
Creator: Qiang, J.; Borland, M.; Kabel, A.; Li, R.; Ryne, R.; Stern, E. et al.
System: The UNT Digital Library
Composite Octet Searches with Jet Substructure (open access)

Composite Octet Searches with Jet Substructure

Many new physics models with strongly interacting sectors predict a mass hierarchy between the lightest vector meson and the lightest pseudoscalar mesons. We examine the power of jet substructure tools to extend the 7 TeV LHC sensitivity to these new states for the case of QCD octet mesons, considering both two gluon and two b-jet decay modes for the pseudoscalar mesons. We develop both a simple dijet search using only the jet mass and a more sophisticated jet substructure analysis, both of which can discover the composite octets in a dijet-like signature. The reach depends on the mass hierarchy between the vector and pseudoscalar mesons. We find that for the pseudoscalar-to-vector meson mass ratio below approximately 0.2 the simple jet mass analysis provides the best discovery limit; for a ratio between 0.2 and the QCD-like value of 0.3, the sophisticated jet substructure analysis has the best discovery potential; for a ratio above approximately 0.3, the standard four-jet analysis is more suitable.
Date: February 14, 2012
Creator: Bai, Yang & Shelton, Jessie
System: The UNT Digital Library
Simple Fully Automated Group Classification on Brain fMRI (open access)

Simple Fully Automated Group Classification on Brain fMRI

We propose a simple, well grounded classification technique which is suited for group classification on brain fMRI data sets that have high dimensionality, small number of subjects, high noise level, high subject variability, imperfect registration and capture subtle cognitive effects. We propose threshold-split region as a new feature selection method and majority voteas the classification technique. Our method does not require a predefined set of regions of interest. We use average acros ssessions, only one feature perexperimental condition, feature independence assumption, and simple classifiers. The seeming counter-intuitive approach of using a simple design is supported by signal processing and statistical theory. Experimental results in two block design data sets that capture brain function under distinct monetary rewards for cocaine addicted and control subjects, show that our method exhibits increased generalization accuracy compared to commonly used feature selection and classification techniques.
Date: April 14, 2010
Creator: Honorio, J.; Goldstein, R.; Honorio, J.; Samaras, D.; Tomasi, D. & Goldstein, R.Z.
System: The UNT Digital Library
Two-photon double ionization of the helium atom by ultrashort pulses (open access)

Two-photon double ionization of the helium atom by ultrashort pulses

Two-photon double ionization of the helium atom was the subject of early experiments at FLASH and will be the subject of future benchmark measurements of the associated electron angular and energy distributions. As the photon energy of a single femtosecond pulse is raised from the threshold for two-photon double ionization at 39.5 eV to beyond the sequential ionization threshold at 54.4 eV, the electron ejection dynamics change from the highly correlated motion associated with nonsequential absorption to the much less correlated sequential ionization process. The signatures of both processes have been predicted in accurate \textit{ab initio} calculations of the joint angular and energy distributions of the electrons, and those predictions contain some surprises. The dominant terms that contribute to sequential ionization make their presence apparent several eV below that threshold. In two-color pump probe experiments with short pulses whose central frequencies require that the sequential ionization process necessarily dominates, a two-electron interference pattern emerges that depends on the pulse delay and the spin state of the atom.
Date: May 14, 2010
Creator: Palacios, Alicia; Horner, Daniel A.; Rescigno, Thomas N. & McCurdy, C. William
System: The UNT Digital Library
Status of PEP-X Light Source Design Study (open access)

Status of PEP-X Light Source Design Study

The SLAC Beam Physics group and other SLAC collaborators continue to study options for implementing a near diffraction-limited ring-based light source in the 2.2-km PEP-II tunnel that will serve the SSRL scientific program in the future. The study team has completed the baseline design for a 4.5-GeV storage ring having 160 pm-rad emittance with stored beam current of 1.5 A, providing >10{sup 22} brightness for multi-keV photon beams from 3.5-m undulator sources. The team has also investigated possible 5-GeV ERL configurations which, similar to the Cornell and KEK ERL plans, would have {approx}30 pm-rad emittance with 100 mA current, and {approx}10 pm-rad emittance with 25 mA or less. Now a 4.5-GeV 'ultimate' storage ring having emittance similar to the ERL and operating with {approx}200 mA is under study. An overview of the progress of the PEP-X design study and SSRL's plans for defining performance parameters that will guide the choice of ring options is presented.
Date: December 14, 2011
Creator: Bane, K. L. F.; Bertsche, K. J.; Cai, Y.; Chao, A.; Huang, X.; Jiao, Y. et al.
System: The UNT Digital Library
From Multileg Loops to Trees (by-passing Feynman's Tree Theorem) (open access)

From Multileg Loops to Trees (by-passing Feynman's Tree Theorem)

We illustrate a duality relation between one-loop integrals and single-cut phase-space integrals. The duality relation is realised by a modification of the customary +i0 prescription of the Feynman propagators. The new prescription regularizing the propagators, which we write in a Lorentz covariant form, compensates for the absence of multiple-cut contributions that appear in the Feynman Tree Theorem. The duality relation can be extended to generic one-loop quantities, such as Green's functions, in any relativistic, local and unitary field theories. The physics program of LHC requires the evaluation of multi-leg signal and background processes at next-to-leading order (NLO). In the recent years, important efforts have been devoted to the calculation of many 2 {yields} 3 processes and some 2 {yields} 4 processes. We have recently proposed a method to compute multi-leg one-loop cross sections in perturbative field theories. The method uses combined analytical and numerical techniques. The starting point of the method is a duality relation between one-loop integrals and phase-space integrals. In this respect, the duality relation has analogies with the Feynman's Tree Theorem (FTT). The key difference with the FTT is that the duality relation involves only single cuts of the one-loop Feynman diagrams. In this talk, we illustrate …
Date: October 14, 2011
Creator: Rodrigo, German; Catani, Stefano; Gleisberg, Tanju; Krauss, Frank & Winter, Jan-Christopher
System: The UNT Digital Library