Search NASA⌕ Search

SEARCH · Search NASA

Results for “R PROCESS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

On-site Destruction of Radioactive Oily Wastes Using Adsorption Coupled with Electrochemical Regeneration - 12221

Arvia{sup R}, working with Magnox Ltd, has developed the technology of adsorption coupled with electrochemical regeneration for the degradation of orphan radioactive oil wastes. The process results in the complete destruction of the organic phase where the radioactivity is transferred to liquid and solid secondary wastes that can then be processed using existing authorised on-site waste-treatment facilities.. Following on from successful laboratory and pilot scale trials, a full scale, site based demonstrator unit was commissioned at the Magnox Trawsfynydd decommissioning site to destroy 10 l of LLW and ILW radioactive oils. Over 99% of the emulsified oil was removed and destroyed with the majority of activity (80 - 90%) being transferred to the aqueous phase. Secondary wastes were disposed of via existing routes with the majority being disposed of via the sites active effluent treatment plant. The regeneration energy required to destroy a litre of oil was 42.5 kWh/l oil. This on-site treatment approach eliminates the risks and cost associated with transporting the active waste oils off site for incineration or other treatment. The Arvia{sup R} process of adsorption coupled with electrochemical regeneration has successfully demonstrated the removal and destruction of LLW and ILW radioactive oils on a nuclear site. Over 99.9% of the emulsified oil was removed, with the majority of the radioactive species transferred to the aqueous, supernate, phase (typically 80 - 90 %). The exception to this is Cs-137 which appears to be more evenly distributed, with 43% associated with the liquid phase and 33 % with the Nyex, the remainder associated with the electrode bed. The situation with Plutonium may be similar, but this requires confirmation, hence further work is underway to understand the full nature of the electrode bed radioactive burden and its distribution within the body of the electrodes. - Tritium gaseous discharges were negligible; hence no off-gas treatment before direct discharge to atmosphere is necessary. All secondary wastes were suitable for disposal using existing disposal routes, with the majority of the activity being successfully discharged as active water via the site active drains. - Oil destruction was achieved at a rate of 28.2 ml/hr using a regeneration energy of 42.5 kWh/l oil. The treatment of different active and non-active oils was achieved using the same operating parameters, providing strong evidence that the process is robust and will treat a wide range of oils, organic wastes and additives. - Currently the design of a plant capable of processing 1000 ml/hr is being established in discussion with Magnox Ltd. The plant will run automatically with little operator attention and so process between 5-8 m{sup 3} of ILW oil per annum. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

A Visual Analytics Paradigm Enabling Trillion-Edge Graph Exploration

We present a visual analytics paradigm and a system prototype for exploring web-scale graphs. A web-scale graph is described as a graph with ~one trillion edges and ~50 billion vertices. While there is an aggressive R&D effort in processing and exploring web-scale graphs among internet vendors such as Facebook and Google, visualizing a graph of that scale still remains an underexplored R&D area. The paper describes a nontraditional peek-and-filter strategy that facilitates the exploration of a graph database of unprecedented size for visualization and analytics. We demonstrate that our system prototype can 1) preprocess a graph with ~25 billion edges in less than two hours and 2) support database query and visualization on the processed graph database afterward. Based on our computational performance results, we argue that we most likely will achieve the one trillion edge mark (a computational performance improvement of 40 times) for graph visual analytics in the near future.

graph visualization↗
DOE OSTI2014

A model for arsenic anti-site incorporation in GaAs grown by hydride vapor phase epitaxy

GaAs growth by hydride vapor phase epitaxy (HVPE) has regained interest as a potential route to low cost, high efficiency thin film photovoltaics. In order to attain the highest efficiencies, deep level defect incorporation in these materials must be understood and controlled. The arsenic anti-site defect, As{sub Ga} or EL2, is the predominant deep level defect in HVPE-grown GaAs. In the present study, the relationships between HVPE growth conditions and incorporation of EL2 in GaAs epilayers were determined. Epitaxial n-GaAs layers were grown under a wide range of deposition temperatures (T{sub D}) and gallium chloride partial pressures (P{sub GaCl}), and the EL2 concentration, [EL2], was determined by deep level transient spectroscopy. [EL2] agreed with equilibrium thermodynamic predictions in layers grown under conditions in which the growth rate, R{sub G}, was controlled by conditions near thermodynamic equilibrium. [EL2] fell below equilibrium levels when R{sub G} was controlled by surface kinetic processes, with the disparity increasing as R{sub G} decreased. The surface chemical composition during growth was determined to have a strong influence on EL2 incorporation. Under thermodynamically limited growth conditions, e.g., high T{sub D} and/or low P{sub GaCl}, the surface vacancy concentration was high and the bulk crystal was close to equilibrium with the vapor phase. Under kinetically limited growth conditions, e.g., low T{sub D} and/or high P{sub GaCl}, the surface attained a high GaCl coverage, blocking As adsorption. This competitive adsorption process reduced the growth rate and also limited the amount of arsenic that incorporated as As{sub Ga}. A defect incorporation model which accounted for the surface concentration of arsenic as a function of the growth conditions, was developed. This model was used to identify optimal growth parameters for the growth of thin films for photovoltaics, conditions in which a high growth rate and low [EL2] could be attained.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Plasma Processing for In-Situ Field Emission Mitigation of Superconducting Radiofrequency (SRF) Cryomodules

Field emission (FE) is one of the main limiting factors of superconducting radio-frequency (SRF) cavities operating in accelerators and it occurs whenever contaminants, like dust, metal flakes or even absorbates, are present on the surface of the cavity high electric field region. Field emission reduces the maximum achievable accelerating field and generates free electrons that may interact with the beam, damage or activate the beamline. One practical method that can be used to mitigate this problem is in-situ plasma cleaning, or plasma processing. The development of a processing that can be applied in-situ is extremely advantageous, since it enables the recovery of the cryomodule performance without the need of disassembling the whole cryomodule, which is an extremely expensive and time-consuming process. On the other hand, plasma processing only requires the cryomodule warm-up to room-temperature and the subsequent processing of the contaminated cavities. The entire process is reasonably quick and involves a limited number of personnel. For these reasons we would like to advocate for continuing to invest in the R&D of plasma processing to optimize its applicability in cryomodules and for extending the technique to other frequency ranges and cavities geometries.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Performance of Zeolite, Silicotitanate, CsTreat{sup R} and SrTreat{sup R} Ion Exchange Materials in Fukushima Clean-up - 17114

The performance of the major facilities used in Fukushima for the treatment of {sup 137}Cs-bearing waters is reviewed. The facilities include Kurion zeolite system, SARRY and the ALPS systems. These utilize chabazite zeolite, silico-titanate CST and hexacyanoferrate based CsTreat{sup R} materials, respectively. The average processing capacity of chabazite is 0.41 m{sup 3}/kg and that of silico-titanate 2.81 m{sup 3}/kg. CsTreat{sup R} material has shown a processing capacity > 38.6 m{sup 3}/kg during its initial operation.A theoretical analysis shows that the selectivity of the materials for cesium over sodium, measured in terms of selectivity coefficient kCs/Na, largely determines their processing capacities. There is a increasing linear relationship between the processing capacity and kCs/Na in logarithmic scales. Also, the decontamination factors obtained with the material for {sup 137}Cs increase with increasing kCs/Na. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1995

Ocean observations with EOS/MODIS: Algorithm development and post launch studies

Several significant accomplishments were made during the present reporting period. (1) Initial simulations to understand the applicability of the MODerate Resolution Imaging Spectrometer (MODIS) 1380 nm band for removing the effects of stratospheric aerosols and thin cirrus clouds were completed using a model for an aged volcanic aerosol. The results suggest that very simple procedures requiring no a priori knowledge of the optical properties of the stratospheric aerosol may be as effective as complex procedures requiring full knowledge of the aerosol properties, except the concentration which is estimated from the reflectance at 1380 nm. The limitations of this conclusion will be examined in the next reporting period; (2) The lookup tables employed in the implementation of the atmospheric correction algorithm have been modified in several ways intended to improve the accuracy and/or speed of processing. These have been delivered to R. Evans for implementation into the MODIS prototype processing algorithm for testing; (3) A method was developed for removal of the effects of the O2 'A' absorption band from SeaWiFS band 7 (745-785 nm). This is important in that SeaWiFS imagery will be used as a test data set for the MODIS atmospheric correction algorithm over the oceans; and (4) Construction of a radiometer, and associated deployment boom, for studying the spectral reflectance of oceanic whitecaps at sea was completed. The system was successfully tested on a cruise off Hawaii on which whitecaps were plentiful during October-November. This data set is now under analysis.

Gordon, Howard R.↗
DOE OSTI2018

Management of the Cs/Sr Capsule Project at the Hanford Site. Technology Readiness Assessment Report

The Federal Project Director (FPD) for the U.S. Department of Energy (DOE), Richland Operations Office (RL) Waste Management and D&D Division (WMD) requested a Technology Readiness Assessment (TRA) for the Management of the Cesium/Strontium Capsule Storage Project (MCSCP) at the Waste Encapsulation and Storage Facility (WESF) on the Hanford Site in Washington State. The MCSCP CD-1 TRA was performed by a team selected in collaboration between the Office of Environmental Management (EM) Chief Engineer (EM-3.3) and RL, WMD FPD. The TRA Team included subject matter and technical experts having experience in cask storage, process engineering, and system design who were independent of the MCSCP, and the team was led by the Director of Operations and Processes from the EM Chief Engineer's Office (EM-3.32). Movement of the Cs/Sr capsules to dry storage, based on information from the conceptual design, involves (1) capsule packaging, (2) capsule transfer, and (3) capsule storage. The project has developed a conceptual process, described in 30059-R-02, "NAC Conceptual Design Report for the Management of the Cesium and Strontium Capsules Project", which identifies the five major activities in the process to complete the transfer from storage pool to pad-mounted cask storage. The process, shown schematically in Figure 1, is comprised of the following process steps: (1) loading capsules into the UCS; (2) UCS processing; (3) UCS insertion into the TSC Basket; (4) cask transport from WESF to CSA and (5) extended storage at the CSA.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS2000

Estimating the Crustal Power Spectrum From Vector Magsat Data: Crustal Power Spectrum

The Earth's magnetic field can be subdivided into core and crustal components and we seek to characterize the crustal part through its spatial power spectrum (R(sub l)). We process vector Magsat data to isolate the crustal field and then invert power spectral densities of flight-local components along-track for R(sub l) following O'Brien et al. [1999]. Our model (LPPC) is accurate up to approximately degree 45 (lambda=900 km) - this is the resolution limit of our data and suggests that global crustal anomaly maps constructed from vector Magsat data should not contain features with wavelengths less than 900 km. We find continental power spectra to be greater than oceanic ones and attribute this to the relative thicknesses of continental and oceanic crust.

Lowe, David A. J.↗
DOE OSTI2020

Innovative Projects on RW Recycling from the French 'Investments for the Future' Program - 20023

The extent and duration of French dismantling operations require to anticipate at the earliest possible stage the management of the large volumes of radioactive waste that will be generated, and to engage collectively in sustainable innovation processes. To anticipate all constraints and requirements related to radioactive waste management and secure the long-term compatibility with waste disposals, the French State has decided to give to Andra, within the 'Investissements d'Avenir' program, an endowment to support innovation at all steps of radioactive waste life cycle with a special emphasis on the dismantling process. Currently, some 30 R and D projects dealing with the optimization of dismantling radioactive waste management are underway. They aim at providing strong innovations in terms of characterization, processing, conditioning and disposal of post dismantling radioactive waste. A specific focus will be made on those dealing with radioactive waste and radionuclides recycling. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Model Authorized Product Realization (MAP-R) Analysis

The Model Authorized Product Realization (MAP-R) project was a collaboration between Sandia National Laboratories (SNL) and Kansas City National Security Campus (KCNSC) to advance the Nuclear Security Enterprise's (NSE) ability to quantify the differences between the current drawing centric/drawing-based process and a part centric/model-based process. In short, MAP-R identified the key business benefits of the part centric model-based process using quantifiable data. MAP-R builds upon the past, but leverages current advances in technology, processes/standards, and the motivation of our current workforce to use a part-centric/model- based design and manufacturing method.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2018

Optimization of Post Dismantling Radwaste Management: a French Innovative Initiative - 18013

The extent and duration of French dismantling operations require the proactive management of the large volumes of radioactive waste to be generated, and that sustainable, innovation processes be engaged. This approach should associate not only the waste producers and dismantling sites operators but also organizations responsible for the safety and waste disposal. The final goal is that all constrains and requirements related to radioactive waste management are anticipated prior to the design stages. While considering those objectives, The French State has decided to give Andra, within the 'Investissements d'Avenir' program, an endowment to support innovation at all steps of radioactive waste life cycle with a special emphasis on the dismantling process. Currently, some 30 R and D projects dealing with the optimization of post dismantling radioactive waste management are underway. They aim at providing strong innovations in terms of characterization, processing, conditioning and disposal of post dismantling radioactive waste. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Enhanced ionization of the non-symmetric HeH{sup +} molecule driven by intense ultrashort laser pulses

We study enhanced single and double ionizations and enhanced single and double excitations in the nonsymmetric two-electron diatomic molecular ion HeH{sup +} in an intense ultrashort laser pulse linearly polarized along the internuclear axis (z axis). We solve a three-dimensional time-dependent Schrödinger equation, TDSE, via correlated two-electron ab initio calculations within the fixed-nuclei approximation. A complex scaling method is used for calculation of both single and double ionizations. These nonperturbative processes increase with large internuclear distance R and reach a maximum at some critical distance R{sub c} and decrease by further increase of R. This enhanced ionization (EI) at R{sub c} is accompanied by enhanced single and double excitation processes. Furthermore, EI is stronger when the permanent dipole moment of the molecule and the electric field at the peak of the laser pulse are antiparallel than when they are parallel. We predict analytically the R{sub c} at which the enhancement of all these molecular processes happens in HeH{sup +} from a simple quasistatic model and investigate the effect of Carrier Envelope Phase on these nonlinear nonperturbative processes.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2024

Data and scripts associated with a manuscript investigating dissolved organic matter and microbial community linkages across seven globally distributed rivers

This data package is associated with the publication “Meta-metabolome ecology reveals that geochemistry and microbial functional potential are linked to organic matter development across seven rivers” submitted to Science of the Total Environment. This data package includes the data necessary to replicate the analyses presented within the manuscript to investigate dissolved organic matter (DOM) development across broad spatial distances and within divergent biomes. Specifically, we included the Fourier transform ion cyclotron mass spectrometry (FTICR-MS) data, geochemistry data, annotated metagenomic data, and results from ecological null modeling analyses in this data package. Additionally, we included the scripts necessary to generate the figures from the manuscript. Complete metagenomic data associated with this data package can be found at the National Center for Biotechnology (NCBI) under Bioproject PRJNA946291. This dataset consists of (1) four folders; (2) a file-level metadata (flmd) file; (3) a data dictionary (dd) file; (4) a factor sheet describing samples; and (5) a readme. The FTICR Data folder contains (1) the processed Fourier transform ion cyclotron mass spectrometry (FTICR-MS) data; (2) a transformation-weighted characteristics dendrogram generated from the FTICR-MS data; and (3) the script used to generate all FTICR-MS related figures. The Geochemical Data folder contains (1) the single geochemistry data file and (2) the R script responsible for generating associated figures. The Metagenomic Data folder contains (1) annotation information across different levels; (2) carbohydrate active enzyme (CAZyme) information from the dbCAN database (Yin et al., 2012); (3) phylogenetic tree data (FASTAs, alignments, and tree file); and (4) the scripts necessary to analyze all of these data and generate figures. The Null Modeling Data folder contains (1) data generated during null modeling for each river and all rivers combined and (2) the R scripts necessary to process the data. All files are .csv, .pdf, .tsv, .tre, .faa, .afa, .tree, or .R.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

A PLATEAU IN THE PLANET POPULATION BELOW TWICE THE SIZE OF EARTH

We carry out an independent search of Kepler photometry for small transiting planets with sizes 0.5-8.0 times that of Earth and orbital periods between 5 and 50 days, with the goal of measuring the fraction of stars harboring such planets. We use a new transit search algorithm, TERRA, optimized to detect small planets around photometrically quiet stars. We restrict our stellar sample to include the 12,000 stars having the lowest photometric noise in the Kepler survey, thereby maximizing the detectability of Earth-size planets. We report 129 planet candidates having radii less than 6 R{sub E} found in three years of Kepler photometry (quarters 1-12). Forty-seven of these candidates are not in Batalha et al., which only analyzed photometry from quarters 1-6. We gather Keck HIRES spectra for the majority of these targets leading to precise stellar radii and hence precise planet radii. We make a detailed measurement of the completeness of our planet search. We inject synthetic dimmings from mock transiting planets into the actual Kepler photometry. We then analyze that injected photometry with our TERRA pipeline to assess our detection completeness for planets of different sizes and orbital periods. We compute the occurrence of planets as a function of planet radius and period, correcting for the detection completeness as well as the geometric probability of transit, R{sub *}/a. The resulting distribution of planet sizes exhibits a power law rise in occurrence from 5.7 R{sub E} down to 2 R{sub E} , as found in Howard et al. That rise clearly ends at 2 R{sub E} . The occurrence of planets is consistent with constant from 2 R{sub E} toward 1 R{sub E} . This unexpected plateau in planet occurrence at 2 R{sub E} suggests distinct planet formation processes for planets above and below 2 R{sub E} . We find that 15.1{sup +1.8}{sub -2.7}% of solar type stars-roughly one in six-has a 1-2 R{sub E} planet with P = 5-50 days.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Adsorption of Zn(II) and Pb(II) Ions from Aqueous Solution Using Chitosan Cross-Linked Formaldehyde Adsorbent to Protect the Environment

Synthesis of chitosan cross-linked formaldehyde was successfully prepared from shrimp chitosan. Characterization of the adsorbent using functional properties such as Fourier transform infrared spectroscopy and scanning electron microscope shows the present of amide and hydroxyl groups at their respective position, also the morphological structure of the adsorbent. Adsorption study of the above adsorbent was carry out for the removal of Zn(II) and Pb(II) from aqueous solution. The effect of cross-linked chitosan dosage, initial concentration, contact time, temperature and pH of the solution for the removal of Zn(II) and Pb(II) were discussed. The optimum dosage required for the removal of Zn(II) and Pb(II) were found to be at 0.4 g at the maximum temperature of 25 °C and the percentage removal were 20.34 and 13.54% respectively. The time required for equilibrium to be reached was 50 min. Effectiveness of the cross-linked adsorbent was observed to increase by increase in contact time. Further studies were also done on isotherms and kinetics of Zn(II) and Pb(II) removal from aqueous solution using chitosan cross-linked formaldehyde. Adsorption Isotherm study conducted from the cross-linked absorbent, shows that the Langmuir plot for the removal of Zn(II) was best fitted with R{sup 2} value of 0.9934, and the adsorption process follows the pseudo second order kinetics with an R{sup 2} value of 0.996. This adsorption process was established to be reversible with an R{sub L} values of zinc (0.8232) and lead (0.8853) respectively. Therefore this implies a successfully reduction in the adsorption of zinc and lead ions from cross-linked formaldehyde solution to protect our environment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗