9 Matching Results

Results open in a new window/tab.

PERFORMANCE IMPROVEMENT OF CROSS-FLOW FILTRATION FOR HIGH LEVEL WASTE TREATMENT (open access)

PERFORMANCE IMPROVEMENT OF CROSS-FLOW FILTRATION FOR HIGH LEVEL WASTE TREATMENT

In the interest of accelerating waste treatment processing, the DOE has funded studies to better understand filtration with the goal of improving filter fluxes in existing cross-flow equipment. The Savannah River National Laboratory (SRNL) was included in those studies, with a focus on start-up techniques, filter cake development, the application of filter aids (cake forming solid precoats), and body feeds (flux enhancing polymers). This paper discusses the progress of those filter studies. Cross-flow filtration is a key process step in many operating and planned waste treatment facilities to separate undissolved solids from supernate slurries. This separation technology generally has the advantage of self-cleaning through the action of wall shear stress created by the flow of waste slurry through the filter tubes. However, the ability of filter wall self-cleaning depends on the slurry being filtered. Many of the alkaline radioactive wastes are extremely challenging to filtration, e.g., those containing compounds of aluminum and iron, which have particles whose size and morphology reduce permeability. Unfortunately, low filter flux can be a bottleneck in waste processing facilities such as the Savannah River Modular Caustic Side Solvent Extraction Unit and the Hanford Waste Treatment Plant. Any improvement to the filtration rate would lead directly …
Date: January 12, 2011
Creator: Duignan, M.; Nash, C. & Poirier, M.
System: The UNT Digital Library
Molecular orientation in soft matter thin films studied by resonant soft X-ray reflectivity (open access)

Molecular orientation in soft matter thin films studied by resonant soft X-ray reflectivity

We present a technique to study depth profiles of molecular orientation in soft matter thin films with nanometer resolution. The method is based on dichroism in resonant soft X-ray reflectivity using linear s- and p-polarization. It combines the chemical sensitivity of Near-Edge X-ray Absorption Fine Structure spectroscopy to specific molecular bonds and their orientation relative to the polarization of the incident beam with the precise depth profiling capability of X-ray reflectivity. We demonstrate these capabilities on side chain liquid crystalline polymer thin films with soft X-ray reflectivity data at the carbon K edge. Optical constants of the anisotropic refractive index ellipsoid were obtained from a quantitative analysis using the Berreman formalism. For films up to 50 nm thickness we find that the degree of orientation of the long axis exhibits no depth variation and isindependent of the film thickness.
Date: January 12, 2011
Creator: Mezger, Markus; Jerome, Blandine; Kortright, Jeffrey B.; Valvidares, Manuel; Gullikson, Eric; Giglia, Angelo et al.
System: The UNT Digital Library
Generation of an amorphous graphite substrate by cumulative deuterium bombardment with full non-bonded interactions (open access)

Generation of an amorphous graphite substrate by cumulative deuterium bombardment with full non-bonded interactions

None
Date: January 12, 2011
Creator: Marian, J.
System: The UNT Digital Library
FURTHER DEVELOPMENT OF MODIFIED MONOSODIUM TITANATE, AN IMPROVED SORBENT FOR PRETREATMENT OF HIGH LEVEL NUCLEAR WASTE AT THE SAVANNAH RIVER SITE (open access)

FURTHER DEVELOPMENT OF MODIFIED MONOSODIUM TITANATE, AN IMPROVED SORBENT FOR PRETREATMENT OF HIGH LEVEL NUCLEAR WASTE AT THE SAVANNAH RIVER SITE

High-level nuclear waste produced from fuel reprocessing operations at the Savannah River Site (SRS) requires pretreatment to remove Cs-137, Sr-90, and alpha-emitting radionuclides (i.e., actinides) prior to disposal onsite as low level waste. Separation processes planned at SRS include caustic side solvent extraction, for Cs-137 removal, and sorption of Sr-90 and alpha-emitting radionuclides onto monosodium titanate (MST). The predominant alpha-emitting radionuclides in the highly alkaline waste solutions include plutonium isotopes Pu-238, Pu-239, and Pu-240. This paper describes recent results from the development of an improved titanate material that exhibits increased removal kinetics and effective capacity for Sr-90 and alpha-emitting radionuclides compared to the baseline MST material.
Date: January 12, 2011
Creator: Taylor-Pashow, K.; Hobbs, D.; Fondeur, F. & Fink, S.
System: The UNT Digital Library
Magnetocrystalline Anisotropy of Magnetic Grains in Co80Pt20:Oxide Thin Films Probed by X-ray Magnetic Circular Dichroism (open access)

Magnetocrystalline Anisotropy of Magnetic Grains in Co80Pt20:Oxide Thin Films Probed by X-ray Magnetic Circular Dichroism

Using angle-dependent x-ray magnetic circular dichroism, we have measured magnetic hysteresis loops at the Co L2,3 edges of oxide-doped Co80Pt20 thin films. The magnetocrystalline anisotropy energy (MAE) of the Co atoms, which is the main source of the magnetocrystalline anisotropy of the CoPt magnetic grains, has been determined directly from these element-specific hysteresis loops. When the oxide volume fraction (OVF) is increased from 16.6% to 20.7%, the Co MAE has been found to decrease from 0.117 meV/atom to 0.076 meV/atom. While a larger OVF helps one to achieve a smaller grain size, it reduces the magnetocrystalline anisotropy, as demonstrated unambiguously from the direct Co MAE measurements. Our results suggest that those Co80Pt20:oxide films with an OVF between 19.1% and 20.7% are suitable candidates for high-density magnetic recording.
Date: January 12, 2011
Creator: Zhang, W.; Morton, S. A.; Wong, P. K. J.; Arenholz, E.; Lu, B.; Cheng, T. Y. et al.
System: The UNT Digital Library
Architecture, design, and numerical simulation of a code/pulse-position-swapping (CPPS) direct translating receiver (open access)

Architecture, design, and numerical simulation of a code/pulse-position-swapping (CPPS) direct translating receiver

None
Date: January 12, 2011
Creator: Mendez, A J; Hernandez, V J; Bennett, C V & Gagliardi, R M
System: The UNT Digital Library
SAVANNAH RIVER SITE INCIPIENT SLUDGE MIXING IN RADIOACTIVE LIQUID WASTE STORAGE TANKS DURING SALT SOLUTION BLENDING (open access)

SAVANNAH RIVER SITE INCIPIENT SLUDGE MIXING IN RADIOACTIVE LIQUID WASTE STORAGE TANKS DURING SALT SOLUTION BLENDING

This paper is the second in a series of four publications to document ongoing pilot scale testing and computational fluid dynamics (CFD) modeling of mixing processes in 85 foot diameter, 1.3 million gallon, radioactive liquid waste, storage tanks at Savannah River Site (SRS). Homogeneous blending of salt solutions is required in waste tanks. Settled solids (i.e., sludge) are required to remain undisturbed on the bottom of waste tanks during blending. Suspension of sludge during blending may potentially release radiolytically generated hydrogen trapped in the sludge, which is a safety concern. The first paper (Leishear, et. al. [1]) presented pilot scale blending experiments of miscible fluids to provide initial design requirements for a full scale blending pump. Scaling techniques for an 8 foot diameter pilot scale tank were also justified in that work. This second paper describes the overall reasons to perform tests, and documents pilot scale experiments performed to investigate disturbance of sludge, using non-radioactive sludge simulants. A third paper will document pilot scale CFD modeling for comparison to experimental pilot scale test results for both blending tests and sludge disturbance tests. That paper will also describe full scale CFD results. The final paper will document additional blending test results …
Date: January 12, 2011
Creator: Leishear, R.; Poirier, M.; Lee, S.; Steeper, T.; Fowley, M. & Parkinson, K.
System: The UNT Digital Library
Groundwater Remediation at the 100-HR-3 Operable Unit Hanford Site Washington USA - 11507 (open access)

Groundwater Remediation at the 100-HR-3 Operable Unit Hanford Site Washington USA - 11507

The 100-HR-3 Groundwater Operable Unit (OU) at the Hanford Site underlies three former plutonium production reactors and the associated infrastructure at the 100-D and 100-H Areas. The primary contaminant of concern at the site is hexavalent chromium; the secondary contaminants are strontium-90, technetium-99, tritium, uranium, and nitrate. The hexavalent chromium plume is the largest plume of its type in the state of Washington, covering an area of approximately 7 km{sup 2} (2.7 mi{sup 2}) with concentrations greater than 20 {micro}g/L. Concentrations range from 60,000 {micro}g/L near the former dichromate transfer station in the 100-D Area to large areas of 20 to 100 {micro}g/L across much of the plume area. Pump-and-treat operations began in 1997 and continued into 2010 at a limited scale of approximately 200 gal/min. Remediation of groundwater has been fairly successful in reaching remedial action objectives (RAOs) of 20 {micro}g/L over a limited region at the 100-H, but less effective at 100-D. In 2000, an in situ, permeable reactive barrier was installed downgradient of the hotspot in 100-D as a second remedy. The RAOs are still being exceeded over a large portion of the area. The CH2M HILL Plateau Remediation Company was awarded the remediation contract for groundwater …
Date: January 12, 2011
Creator: Smoot, J. L.; Biebesheimer, F. H.; Eluskie, J. A.; Spiliotopoulos, A.; Tonkin, M. J. & Simpkin, T.
System: The UNT Digital Library
Bioinformatics tools for cancer metabolomics (open access)

Bioinformatics tools for cancer metabolomics

This review focuses on the use of different bioinformatics tools in cancer metabolomics studies.
Date: January 12, 2011
Creator: Blekherman, Grigoriy; Laubenbacher, Reinhard; Cortes, Diego F.; Mendes, Pedro; Torti, Frank M.; Akman, Steven et al.
System: The UNT Digital Library