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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.

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At least 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Dry Pretreatment of Used Nuclear Fuel for Tritium Removal: A Review

Virtually all the elements in the periodic chart are generated as a result of atomic fission in nuclear fuel. Several of the elements are volatile or can readily react with other chemicals to form volatile molecules that can be released during the processing of used nuclear fuel for the recovery of the valuable products. Among the volatile fission products, {sup 129}I, {sup 14}C, {sup 3}H, {sup 85}Kr, and {sup 79}Se constitute the main environmental concern for uncontrolled release. Storage of used fuel allows the short-lived isotopes to decay significantly (e.g., {sup 3}H decays in half every 12.32 years and {sup 85}Kr every 10.76 years). However, depending on regulatory limits they may remain an environmental concern up to about 50-100 years of fuel storage. In contrast, the concern for environmental release of the highly mobile {sup 129}I and {sup 14}C remains for geological times (half-lives of 15.7 million years for {sup 129}I and 5730 years for {sup 14}C). Processing of used commercial nuclear fuel requires significant head-end operations to remove the fuel from the protective coverings (e.g., assemblies). The current industrial process includes cropping the end caps of the fuel assemblies, chopping of the fuel pins and/or bundles into short segments, and prolonged leaching of the segments using concentrated nitric acid (HNO{sub 3}). The infrastructure, processes, and waste treatment systems in the head-end operations, including the associated off-gas system, are some of the larger and more costly components of the entire plant. The bulk of the volatile fission products are released to the off-gas during the leaching and dissolution. However, a small but significant amount will transfer to the following steps of processing such as solvent extraction and will show up in many different waste streams. The effective capture of {sup 3}H and iodine throughout the different processes and disposition of associated waste streams is costly and complicated. Up-front removal and capture is highly desirable. Currently, at the U.S. Department of Energy national laboratories and internationally, several dry pretreatment technologies are being studied and developed with the potential to simplify and increase the safety of subsequent storage or chemical recycling processes. These studies include (1) alternative decladding methods, (2) oxidation of exposed fuel following either conventional shearing or chemical decladding, and (3) the collection and stabilization of released volatile radionuclides. Several dry processes are being developed for the up-front removal of tritium and other fission products. They can be combined with different decladding alternatives and, in general, produce a fine powder that can be fed to aqueous or pyrochemical separations processes. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

Synthesis of nano-forsterite powder by making use of natural silica sand

Nano-forsterite powder with natural silica sand and magnesium powder as the raw materials have been succesfully synthesized. The silica sand was purified followed by a coprecipitation process to obtain colloidal silica. The magnesium powder was dissolved in a chloric acid solution to obtain MgCl{sub 2} solution. The nanoforsterite powder was synthesised using a sol-gel method which included the mixing the colloidal silica and the MgCl{sub 2} solution with various aging and filtering processes. The samples were dried at 100 °C using a hot plate and then the dried powders were calcinated at 900 °C for 2 hours. The samples were characetised for their elements and phase compositions using X-ray Flourescence (XRF) and X-ray Diffraction (XRD) methods, respectively. The diffraction data were qualitatively analyzed using Match!2 software and quantitatively using Rietica software. The crystallite size was verified using Transmission Electron Microscopy (TEM). Results of XRD data analysis showed that the forsterite content reached up to 90.5% wt. The TEM average crystallite size was approximately 53(6) nm.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Effect of the hydration temperature on the microstructure of Class G cement: C-S-H composition and density

Curing temperature has a significant influence on cement paste microstructure and the properties of its principal hydrate C-S-H. In this paper, the effect of the hydration temperature in the range of 7 °C to 90 °C on the microstructure of a class G oil-well cement is studied. This is done by combining various experimental methods, including X-ray diffraction associated with the Rietveld analysis, thermo-gravimetric analysis, mercury intrusion porosimetry and porosity evaluation by drying. The experimental results show an increase of the capillary porosity and a decrease of the gel porosity by increasing the hydration temperature. This is attributed to a decrease of the C-S-H intrinsic porosity and a corresponding increase of the C-S-H density for higher curing temperatures. The experimental results are used in a simple analysis method to evaluate the density of C-S-H, as well as its C/S ratio and H/S ratio in dry and saturated conditions. The evaluated C-S-H density varies from 1.88 g/cm{sup 3} at 7 °C to 2.10 g/cm{sup 3} at 90 °C. The results also show a decrease of molar C/S ratio with increasing hydration temperature from 1.93 at 7 °C to 1.71 at 90 °C and of the H/S ratio from 5.1 at 7 °C to 2.66 at 90 °C.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Design, testing and emplacement of sand-bentonite for the construction of a gas-permeable seal test (gast)

The main aim of a gas-permeable seal is to increase the gas transport capacity of the backfilled underground structures without compromising the radionuclide retention capacity of the engineered barrier system or the host rock. Such a seal, proposed by NAGRA as part of the 'Engineered Gas Transport System' in a L/ILW repository, considers specially designed backfill and sealing materials such as sand/bentonite (S/B) mixtures with a bentonite content of 20- 30%. NAGRA's RD and D plan foresees demonstrating the construction and performance of repository seals and improving the understanding and the database for reliably predicting water and gas transport through these systems. The fluid flow and gas transport properties of these backfills have been determined at the laboratory scale and through modelling the maximum gas pressures in the near field of a repository system and the gas flow rates have been evaluated. Within this context, the Gas-permeable Seal Test (GAST) was constructed at Grimsel Test Site (GTS) to validate the effective functioning of gas-permeable seals at realistic scale. The intrinsic permeability of such seals should be in the order of 10-18 m2. Because the construction of S/B seals is not common practice for construction companies, a stepwise approach was followed to evaluate different construction and quality assurance methods. As a first step, an investigation campaign with simple tests in the laboratory and in the field followed by 1:1 scale pre-tests at GTS was performed. Through this gradual increase of the degree of complexity, practical experience was gained and confidence in the methods and procedures to be used was built, which allowed reliably producing and working with S/B mixtures at a realistic scale. During the whole pre-testing phase, a quality assurance (QA) programme for S/B mixtures was developed and different methods were assessed. They helped to evaluate and choose appropriate emplacement techniques and methodologies to achieve the target S/B dry density of 1.70 g/cm{sup 3}, which results in the desired intrinsic permeability throughout the experiment. The final QA methodology was targeted at engineering measures to decide if the work can proceed, and at producing high resolution material properties database for future water and gas transport modelling activities. The different applied QA techniques included standard core cutter tests, the application of neutron-gamma (Troxler) probes and two mass balance methods (2D and 3D). The methods, looking at different representative scales, have provided only slightly different results and showed that the average density of the emplaced S/B plug was between 1.65 and 1.73 g/cm{sup 3}. Spatial variability of dry densities was observed at decimeter scale. Overall, the pre-testing and QA programme performed for the GAST project demonstrated how the given design criteria and requirements can be met by appropriately planning and designing the material emplacement. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Development of Robotic Multisensor Inspection System for Used Nuclear Fuel Canisters

Dry storage of used nuclear fuel is an integral part of the fuel cycle and methods to inspect the canisters that confine the used fuel rods are being established. The challenges for inspection systems include geometric constraints, elevated temperature, and radiation. A novel robotic inspection system focusing on stress corrosion cracking capable of in-situ surface composition characterization and crack detection is under development. The delivery system, laser induced breakdown spectroscopy for surface composition, and ultrasonic guided waves for crack detection are summarized herein. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS2006

The Validation of Vapor Phase Hydrogen Peroxide Microbial Reduction for Planetary Protection and a Proposed Vacuum Process Specification

The Jet Propulsion Laboratory, in conjunction with the NASA Planetary Protection Officer, has selected the vapor phase hydrogen peroxide sterilization process for continued development as a NASA approved sterilization technique for spacecraft subsystems and systems. The goal is to include this technique, with an appropriate specification, in NPR 8020.12C as a low temperature complementary technique to the dry heat sterilization process.To meet microbial reduction requirements for all Mars in-situ life detection and sample return missions, various planetary spacecraft subsystems will have to be exposed to a qualified sterilization process. This process could be the elevated temperature dry heat sterilization process (~115 C for 40 hours) which was used to sterilize the Viking lander spacecraft. However, with utilization of such elements as highly sophisticated electronics and sensors in modern spacecraft, this process presents significant materials challenges and is thus an undesirable bioburden reduction method to design engineers. The objective of this work is to introduce vapor hydrogen peroxide (VHP) as an alternative to dry heat microbial reduction to meet planetary protection requirements.The VHP process is widely used by the medical industry to sterilize surgical instruments and biomedical devices, but high doses of VHP may degrade the performance of flight hardware, or compromise material properties. Our goal for this study was to determine the minimum VHP process conditions to achieve microbial reduction levels acceptable for planetary protection.

planetary protection↗
DOE OSTI2016

Techno-economic analysis comparison of comminution of wood chips using a hammer mill and a rotary shear

Preprocessing is a crucial step in the utilization of biomass feedstocks for the production of fuel and biomaterials [1]. Size reduction and drying of the material, where used, are two of the most costly and energy intensive operations that are undertaken during preprocessing, reduction of the energy usage during these two phases will reduce cost of processing and ultimately reduce the overall cost to the final user. Traditionally, a hammer mill has been the primary method used for secondary size reduction. For wet material, a hammer mill requires high amounts of energy, while for dry material the hammer mill produces a large quantity of small particles [2]. In both cases, the costs increase either from additionally needed fuel cost or from the cost of lost material. In effort to lower the cost for size reduction, a rotary shear has been developed for the comminution of biomass feedstocks. The rotary shear utilizes interlocking, rotating disk that shear the material rather than using impact to reduce the particle size of the materials. Because the material is size reduced using a cutting motion, rather than impact, the distribution of particle sizes is much narrower than produced by hammer mills.

09 BIOMASS FUELS↗
DOE OSTI2023

Technoeconomic assessment of distillation heat transfer intensification using aeroelastically fluttering reeds

Dry cooling, where forced air is the heat transfer medium, is a preferable cooling method in arid locations lacking readily available process water. However, such locations often experience high ambient temperatures that limit the effectiveness of air cooling. The objective of this study is to quantify the economic and energetic benefits of heat transfer intensification via the implementation of aeroelastically fluttering reeds to the air-cooled condenser of a methanol distillation column. Condenser size and performance, regarding recovered methanol and required fan power, is evaluated across condenser operating temperatures (T cond ) from 60 to 62°C and heat transfer coefficients (U) U base –2U base for a range of inlet air temperatures based on ambient temperature data from Yuma, Arizona. Under typical design sizing, condenser capital cost was reduced by 6%–35% (1.3U base –2U base ) and nominal methanol recovery was increased from 0.26% to 0.38% (T cond = 62–60°C). At optimized condenser size, all enhanced U and T cond pairs increase methanol recovery and reduce fan power costs compared to the optimal Ubase reference. Overall, using enhanced heat transfer to maintain condenser temperature under a wider range of inlet conditions, rather than to reduce operation temperature, produces more favorable performance. Methanol price is not a determining factor in which pairs are profitable. Analysis was repeated for a global warming scenario, revealing more valuable improvements under elevated temperatures. Energy savings from condenser improvement to a methanol production system are not significant with respect to an optimized conventional system. Furthermore, unit economic and energetic incentives suggest implementation of fluttering reeds may be justified in other applications.

42 ENGINEERING↗
DOE OSTI2019

Calculation of supersaturation maximum and droplet concentration at cloud boundaries

Most parameterizations of droplet concentration at cloud base in cloud models are derived under the assumption that all droplets at the cloud base form by nucleation of dry CCN crossing the lifting condensation level in updraft. In this study, a novel method of calculation of the supersaturation maximum and droplet concentration at cloud base is described that takes into account the existence of liquid at the level of droplet nucleation. Liquid exists in haze particles, as well as in the form of cloud droplets and raindrops. It is shown that the presence of liquid water inside non-activated CCN, as well as of cloud droplets and raindrops substantially decreases supersaturation maximum in case of high aerosol concentration. The possible effect of the supersaturation maximum decrease on formation of DSD in clouds is discussed. The method can be also applied to calculation of supersaturation and droplet nucleation at cloud edges.

58 GEOSCIENCES↗
DOE OSTI2014

Phase 2 Study of Concurrent Cetuximab Plus Definitive Thoracic Radiation Therapy Followed by Consolidation Docetaxel Plus Cetuximab in Poor Prognosis or Elderly Patients With Locally Advanced Non-Small Cell Lung Cancer

Background: Recursive partitioning analysis has shown that Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) ≥2, male sex, and age ≥70 years are prognostic of poor outcome in locally advanced non-small cell lung cancer (LA-NSCLC) patients. Concurrent chemoradiation therapy (CRT) improves survival, but toxicity is a concern in this frail patient cohort. We therefore opened this trial of concurrent definitive thoracic radiation therapy (XRT) and cetuximab, followed by consolidation docetaxel plus cetuximab. Methods and Materials: Eligible patients had pathologically proven, unresectable LA-NSCLC (stage IIA-“dry” IIIB). They had ECOG PS 2 or weight loss ≥5% in 3 months or were aged ≥70 years. The primary objective was progression-free survival (PFS). Secondary objectives included overall survival (OS) and overall response rate (ORR). Results: From May 2008 to November 2010, a total of 32 patients were evaluated in our single-institution, institutional review board–approved prospective clinical trial. Three patients were screen failures and 2 more withdrew consent before treatment, leaving 27 evaluable patients. One was removed because of poor therapy compliance, and 2 were taken off trial because of grade 3 cetuximab-related toxicities but were followed up under intent-to-treat analysis. The median follow-up and OS were 10.5 months. The median PFS was 7.5 months. The ORR was 59.3%. Eight early/sudden deaths were reported. Upon review, 6 patients developed severe pulmonary complications. Conclusions: Patients enrolled in this trial had improved OS compared with poor-PS historical controls (10.5 vs 6.4 months) and comparable OS to good-PS historical controls (10.5 vs 11.9 months) treated with XRT alone. However, pulmonary toxicity is a concern. Consolidative cetuximab/docetaxel, in conjunction with high-dose radiation therapy, is a putative cause.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Novel synthesis of Zr{sub x}Ti{sub 1-x}O{sub n} mixed oxides using titanyl sulphate and pressurized hot and supercritical fluids, and their photocatalytic comparison with sol-gel prepared equivalents

Highlights: • Novel preparation of Zr{sub x}Ti{sub 1-x}O{sub n} mixed oxides by using titanyl sulphate and pressurized hot water and supercritical methanol. • Comparison of photoactivity of prepared mixed oxides with sol-gel-prepared equivalents in Acid orange 7 photodegradation. • The highest photoactivity of TiO{sub 2}-H is attributed to small anatase crystallite-size. • The highest photoactivity of Zr{sub 0.1}Ti{sub 0.9}O{sub n}-G is attributed to the existence of anatase-brookite phase mixture and small anatase crystallite-size. • The optimum Zr loading in TiO{sub 2} is below 10·mol%. - Abstract: Zr{sub x}Ti{sub 1-x}O{sub n} mixed oxides with five various molar ratios of Zr:Ti and their parent oxides were prepared, combining thermal hydrolysis (H) with pressurized hot water crystallization and supercritical methanol drying. Their photoactivity was compared to equivalent materials prepared by sol-gel (G) method. Zr{sub 0.1}Ti{sub 0.9}O{sub n}-G was the most photoactive mixed oxide, which showed significantly higher photoactivity than Zr{sub 0.1}Ti{sub 0.9}O{sub n}-H. Higher photoactivity of Zr{sub 0.1}Ti{sub 0.9}O{sub n}-G can be attributed to phase composition (anatase-brookite phase mixture) and smaller TiO{sub 2} anatase crystallite-size. The Zr dopation in TiO{sub 2} did not improve the photoactivity neither of sol-gel-synthetized, nor thermal hydrolysis-synthetized mixed oxides in AO7 photodegradation. Zr in higher loadings (>10 mol%) formed separate monoclinic and tetragonal ZrO{sub 2} and monoclinic zirconium titanates{sub .} Unlike Zr{sup 4+} ions in Zr doped TiO{sub 2} the separate monoclinic and tetragonal ZrO{sub 2} and monoclinic zirconium titanates did not serve as electron trapping centres but as electron-hole recombination centres. The Zr loading in TiO{sub 2} should be below 10 mol%.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Using Ambient Noise Seismic Interferometry and Local and Teleseismic Earthquakes to Determine Crustal Thickness and Moho Structure of the Northwestern Gulf of Mexico Margin

Abstract The northwestern part of the Gulf of Mexico has undergone two episodes of continental rifting and collision and produced structural artifacts that are now buried under many kilometers of sediments, complicating investigations of the region. The deep sedimentary package precludes outcrops and points to a need for the application of seismic techniques, but low rates of seismicity in the region and sparse seismic monitoring limit the utility of traditional seismic methods. We therefore use diverse data to perform two‐dimensional seismic tomography across the dry land portion of the margin. Data are gleaned from teleseismic and regional earthquakes, postcritical SsPmp arrivals, and direct P wave energy identified with seismic interferometry that were recorded by a broadband, three‐component array and partially overlapping short‐period, vertical‐component array. The Pn and postcritical SsPmp phase help constrain the Moho discontinuity, which a previous receiver function study suggested was absent beneath the seaward portion of this transect. A high‐velocity body is observed in the crust at the same location as the Houston Magnetic Anomaly, possibly marking rocks from the Alleghenian continental assembly. The crust thins from NW to SE, indicating that extension occurred mostly to the south of the Ouachita orogeny. Our model indicates that the margin's sediment package reaches a maximum thickness of ~15 km at the coast and becomes unresolvably thin near the Llano Uplift.

58 GEOSCIENCES↗
DOE OSTI2012

Cloud Condensation Nuclei Profile Value-Added Product

The cloud condensation nuclei (CCN) concentration at cloud base is the most relevant measure of the aerosol that influences droplet formation in clouds. Since the CCN concentration depends on supersaturation, a more general measure of the CCN concentration is the CCN spectrum (values at multiple supersaturations). The CCN spectrum is now measured at the surface at several fixed ARM sites and by the ARM Mobile Facility (AMF), but is not measured at the cloud base. Rather than rely on expensive aircraft measurements for all studies of aerosol effects on clouds, a way to project CCN measurements at the surface to cloud base is needed. Remote sensing of aerosol extinction provides information about the vertical profile of the aerosol, but cannot be directly related to the CCN concentration because the aerosol extinction is strongly influenced by humidification, particularly near cloud base. Ghan and Collins (2004) and Ghan et al. (2006) propose a method to remove the influence of humidification from the extinction profiles and tie the “dry extinction” retrieval to the surface CCN concentration, thus estimating the CCN profile. This methodology has been implemented as the CCN Profile (CCNPROF) value-added product (VAP).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Liquid Secondary Waste Grout Formulation and Waste Form Qualification

This report describes the results from liquid secondary waste (LSW) grout formulation and waste form qualification tests performed at Pacific Northwest National Laboratory (PNNL) for Washington River Protection Solutions (WRPS) to evaluate new formulations for preparing a grout waste form with high-sulfate secondary waste simulants and the release of key constituents from these grout monoliths. Specific objectives of the LSW grout formulation and waste form qualification tests described in this report focused on five activities: 1.preparing new formulations for the LSW grout waste form with high-sulfate LSW simulants and solid characterization of the cured LSW grout waste form; 2.conducting the U.S. Environmental Protection Agency (EPA) Method 1313 leach test (EPA 2012) on the grout prepared with the new formulations, which solidify sulfate-rich Hanford Tank Waste Treatment and Immobilization Plant (WTP) off-gas condensate secondary waste simulant, using deionized water (DIW); 3.conducting the EPA Method 1315 leach tests (EPA 2013) on the grout monoliths made with the new dry blend formulations and three LSW simulants (242-A evaporator condensate, Environmental Restoration Disposal Facility (ERDF) leachate, and WTP off-gas condensate) using two leachants, DIW and simulated Hanford Integrated Disposal Facility (IDF) Site vadose zone pore water (VZPW); 4.estimating the 99 Tc desorption K d (distribution coefficient) values for 99 Tc transport in oxidizing conditions to support the IDF performance assessment (PA); 5.estimating the solubility of 99 Tc(IV)-bearing solid phases for 99 Tc transport in reducing conditions to support the IDF PA.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Delayed Gamma-ray Spectroscopy for Safeguards Applications

The delayed gamma-ray assay technique utilizes an external neutron source (D-D, D-T, or electron accelerator-driven), and high-resolution gamma-ray spectrometers to perform characterization of SNM materials behind shielding and in complex configurations such as a nuclear fuel assembly. High-energy delayed gamma-rays (2.5 MeV and above) observed following the active interrogation, provide a signature for identification of specific fissionable isotopes in a mixed sample, and determine their relative content. Potential safeguards applications of this method are: 1) characterization of fresh and spent nuclear fuel assemblies in wet or dry storage; 2) analysis of uranium enrichment in shielded or non-characterized containers or in the presence of a strong radioactive background and plutonium contamination; 3) characterization of bulk and waste and product streams at SNM processing plants. Extended applications can include warhead confirmation and warhead dismantlement confirmation in the arms control area, as well as SNM diagnostics for the emergency response needs. In FY16 and prior years, the project has demonstrated the delayed gamma-ray measurement technique as a robust SNM assay concept. A series of empirical and modeling studies were conducted to characterize its response sensitivity, develop analysis methodologies, and analyze applications. Extensive experimental tests involving weapons-grade Pu, HEU and depleted uranium samples were completed at the Idaho Accelerator Center and LLNL Dome facilities for various interrogation time regimes and effects of the neutron source parameters. A dedicated delayed gamma-ray response modeling technique was developed and its elements were benchmarked in representative experimental studies, including highresolution gamma-ray measurements of spent fuel at the CLAB facility in Sweden. The objective of the R&D effort in FY17 is to experimentally demonstrate the feasibility of the delayed gamma-ray interrogation of shielded SNM samples with portable neutron sources suitable for field applications.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2022

Coal Fired Power Plant Configuration and Operation Impact on Plant Effluent Contaminants and Conditions

The primary objective of this project is to characterize coal contaminants in coal-fired power plant wastewater as a function of coal type, unit configurations, and unit operation profile with uncertainty analysis. This project was in response to the U.S. Department of Energy (DOE) Solicitation DE-FOA-0001842. The project duration was between September 01, 2018, and December 31, 2021 (no-cost extension filed, due to the Covid-19 pandemic restrictions, and approved). Field and lab test program was conducted with the main goal to characterize coal contaminants in coal-fired power plant wastewater as a function of coal type, unit configurations, and unit operation profile with uncertainty analysis. In this project, the team of Lehigh University (prime recipient) and Western Kentucky University identified two suitable Thermoelectric Power Plants (TTPs) firing bituminous and sub-bituminous coals respectively, designed test plans, and performed sample collection. Sampling included coal from each TTPs power generation units, Wet Flue Gas Desulfurization (WFGD) slurry material and waste-water samples taken from the outlet of the water treatment tank prior to discharge and other pertinent locations. Coal samples are dried, crushed, and pulverized according to the American Society for Testing and Materials (ASTM) methods. The prepared coal samples are analyzed for normal proximate and ultimate analysis tests in addition to the toxic metals and anions according to ASTM methods. The FGD slurry materials are analyzed for toxic metals and anions according to Electric Power Research Institute (EPRI) or Environmental Protection Agency (EPA) methods, as appropriate. The wastewater samples from the water treatment tank outlet are analyzed for toxic metals and anions according to EPA methods. The effluent species analyzed include mercury, arsenic, selenium, nitrate/nitrite, bromide, and chlorine. This project provided results of effluent conditions as a function of coal type, unit configuration, and unit operation profile, and identified the levels of uncertainty in the effluent results.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2023

Retrieved Number Concentration of Cloud Condensation Nuclei (RNCCN) Profile Value-Added Product Report

The cloud condensation nuclei (CCN) concentration at cloud base is the most relevant measure of the aerosol that influences droplet formation in clouds. Since the CCN concentration depends on supersaturation, a more general measure of the CCN concentration is the CCN spectrum (values at multiple supersaturations). The CCN spectrum is now measured at the surface at several U.S. Department of Energy Atmospheric Radiation Measurement (ARM) user facility observatories and by the ARM Mobile Facility (AMF) but is not measured at the cloud base. Rather than rely on expensive aircraft measurements for all studies of aerosol effects on clouds, a way to project CCN observations made at the surface to cloud base is needed. Remote sensing of aerosol extinction provides information about the vertical profile of the aerosol but cannot be directly related to the CCN concentration because the aerosol extinction is strongly influenced by humidification, particularly near cloud base. Ghan and Collins (2004) and Ghan et al. (2006) propose a method to remove the influence of humidification from the extinction profiles and tie the “dry extinction” retrieval to the surface CCN concentration, thus estimating the CCN profile. This methodology has been implemented as ARM’s Retrieved Number Concentration of CCN (RNCCN) Profile Value-Added Product (VAP).

54 ENVIRONMENTAL SCIENCES↗