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Aiken, SC, United States

The Savannah River National Laboratory is the applied research and development laboratory at the U.S. Department of Energy’s Savannah River Site near Jackson, South Carolina. SRNL was founded in 1951 as the Savannah River Laboratory. It was certified as a national laboratory on May 7, 2004.SRNL research topics include environmental remediation, technologies for the hydrogen economy, handling of hazardous materials, and technologies for prevention of nuclear proliferation. The laboratory has specific experience in vitrification of nuclear waste and hydrogen storage initially developed to support production of tritium and plutonium at the Savannah River Site during the Cold War. SRNL is a founding member of the South Carolina Hydrogen & Fuel Cell Alliance .The laboratory employs 945 people and has an annual budget of 210 million U.S. Dollars .Savannah River National Laboratory has been operated by Savannah River Nuclear Solutions, LLC for the U.S. Department of Energy since 2008. Savannah River Nuclear Solutions, LLC is a partnership consisting of Fluor Corporation, Newport News Nuclear, Inc. and Honeywell International. Wikipedia.

Kurzeja R.,Savannah River National Laboratory
Boundary-Layer Meteorology | Year: 2010

Experiments and calculations were conducted with a 0.13 mm fine wire thermocouple within a naturally-aspirated Gill radiation shield to assess and improve the accuracy of air temperature measurements without the use of mechanical aspiration, wind speed or radiation measurements. It was found that this thermocouple measured the air temperature with root-mean-square errors of 0.35 K within the Gill shield without correction. A linear temperature correction was evaluated based on the difference between the interior plate and thermocouple temperatures. This correction was found to be relatively insensitive to shield design and yielded an error of 0.16 K for combined day and night observations. The correction was reliable in the daytime when the wind speed usually exceeds 1 m s-1 but occasionally performed poorly at night during very light winds. Inspection of the standard deviation in the thermocouple wire temperature identified these periods but did not unambiguously locate the most serious events. However, estimates of sensor accuracy during these periods is complicated by the much larger sampling volume of the mechanically-aspirated sensor compared with the naturally-aspirated sensor and the presence of significant near-surface temperature gradients. The root-mean-square errors therefore are upper limits to the aspiration error since they include intrinsic sensor differences and intermittent volume sampling differences. © 2009 Springer Science+Business Media B.V.

Lingam K.,Clemson University | Podila R.,Clemson University | Qian H.,Clemson University | Serkiz S.,Savannah River National Laboratory | Rao A.M.,Clemson University
Advanced Functional Materials | Year: 2013

For a practical realization of graphene-based logic devices, the opening of a band gap in graphene is crucial and has proven challenging. To this end, several synthesis techniques, including unzipping of carbon nanotubes, chemical vapor deposition, and other bottom-up fabrication techniques have been pursued for the bulk production of graphene nanoribbons (GNRs) and graphene quantum dots (GQDs). However, only limited progress has been made towards a fundamental understanding of the origin of strong photoluminescence (PL) in GQDs. Here, it is experimentally shown that the PL is independent of the functionalization scheme of the GQDs. Following a series of annealing experiments designed to passivate the free edges, the PL in GQDs originates from edge-states, and an edge-passivation subsequent to synthesis quenches the PL. The results of PL studies of GNRs and carbon nano-onions are shown to be consistent with PL being generated at the edge sites of GQDs. The origin of the photoluminescence (PL) behavior of graphene quantum dots (GQDs) is investigated. Following a series of annealing experiments designed to passivate the free edges, the PL in GQDs originates from edge-states, and an edge-passivation subsequent to synthesis quenches the PL. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gorensek M.B.,Savannah River National Laboratory
International Journal of Hydrogen Energy | Year: 2011

Two hybrid sulfur (HyS) cycle process flowsheets intended for use with high-temperature gas-cooled reactors (HTGRs) are presented. The flowsheets were developed for the Next Generation Nuclear Plant (NGNP) program, and couple a proton exchange membrane (PEM) electrolyzer for the SO2-depolarized electrolysis step with a silicon carbide bayonet reactor for the high-temperature decomposition step. One presumes an HTGR reactor outlet temperature (ROT) of 950 °C, the other 750 °C. Performance was improved (over earlier flowsheets) by assuming that use of a more acid-tolerant PEM, like acid-doped poly[2,2′-(m-phenylene)-5,5′-bibenzimidazole] (PBI), instead of Nafion®, would allow higher anolyte acid concentrations. Lower ROT was accommodated by adding a direct contact exchange/quench column upstream from the bayonet reactor and dropping the decomposition pressure. Aspen Plus was used to develop material and energy balances. A net thermal efficiency of 44.0-47.6%, higher heating value basis is projected for the 950 °C case, dropping to 39.9% for the 750 °C case. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Flach G.P.,Savannah River National Laboratory
Ground Water | Year: 2012

Dual-domain solute transport models produce significantly improved agreement to observations compared to single-domain (advection-dispersion) models when used in an a posteriori data fitting mode. However, the use of dual-domain models in a general predictive manner has been a difficult and persistent challenge, particularly at field-scale where characterization of permeability and flow is inherently limited. Numerical experiments were conducted in this study to better understand how single-rate mass transfer parameters vary with aquifer attributes and contaminant exposure. High-resolution reference simulations considered 30 different scenarios involving variations in permeability distribution, flow field, mass transfer timescale, and contaminant exposure time. Optimal dual-domain transport parameters were empirically determined by matching to breakthrough curves from the high-resolution simulations. Numerical results show that mobile porosity increases with lower permeability contrast/variance, smaller spatial correlation length, lower connectivity of high-permeability zones, and flow transverse to strata. A nonzero non-participating porosity improves empirical fitting, and becomes larger for flow aligned with strata, smaller diffusion coefficient, and larger spatial correlation length. The non-dimensional mass transfer coefficient or Damkohler number tends to be close to 1.0 and decrease with contaminant exposure time, in agreement with prior studies. The best empirical fit is generally achieved with a combination of macrodispersion and first-order mass transfer. Quantitative prediction of ensemble-average dual-domain parameters as a function of measurable aquifer attributes proved only marginally successful. Ground Water © 2011, National Ground Water Association. Published 2011. This article is a U.S. Government work and is in the public domain in the USA.

Ghassemi H.,Michigan Technological University | Au M.,Savannah River National Laboratory | Chen N.,Michigan Technological University | Heiden P.A.,Michigan Technological University | Yassar R.S.,Michigan Technological University
ACS Nano | Year: 2011

In situ electrochemical lithiation and delithiation processes inside a nanobattery consisting of an individual amorphous Si nanorod and ionic liquid were explored. Direct formation of the crystalline Li22Si5 phase due to the intercalation of Li ions was observed. In addition, the role of the electrolyte-nanorod interface was examined. It was observed that the lithiation of Si nanorods is dominated by surface diffusion. Upon the delithiation process, partial decomposition of Li22Si5 particles was observed which can explain the irreversible capacity loss that is generally seen in Si anodes. This study shows that the radial straining due to lithiation does not cause cracking in nanorods as small in diameter as 26 nm, whereas cracks were observed during the lithiation of 55 nm Si nanorods. © 2011 American Chemical Society.

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