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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Increased abundance of a common scavenger affects allocation of carrion but not efficiency of carcass removal in the Fukushima Exclusion Zone

Abstract The 2011 nuclear accident in Fukushima, Japan caused the evacuation of > 100,000 people and prompted studies on environmental impacts of radiological contamination. However, few researchers have explored how the human evacuation has affected ecosystem processes. Despite contamination, one common scavenger (wild boar, Sus scrofa ) is 2–3× more abundant inside the Fukushima Exclusion Zone (FEZ). Shifts in abundance of some scavenger species can have cascading effects on ecosystems, so our objective was to investigate impacts of the evacuation and the resulting increase in wild boar on vertebrate scavenger communities. We deployed cameras at 300 carcasses in the FEZ and a nearby inhabited area, and quantified carcass fate, scavenger species, and detection/persistence times. We also tested effects of carcass size and habitat on scavenger community composition and efficiency by balancing trials across two carcass sizes and habitats in each zone. Overall scavenger richness and carcass removal rates (73%) were similar in the FEZ and inhabited area, but species-specific carcass removal rates and occurrence differed between zones. Wild boar removed substantially more carcasses inside the FEZ, with implications for nutrient and contaminant distribution. Our results suggest carcass size affects scavenging dynamics more than human activity or habitat, and abundance changes of common scavengers can influence carrion resource allocation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Layered zinc hydroxide as an adsorbent for phosphate removal and recovery from wastewater

At present, phosphate removal and recovery from wastewater is gaining wide attention due to the dual issues of eutrophication, caused by the increased production of algae, and universal phosphorus scarcity. In this study, a layered zinc hydroxide (LZH) was synthesized by a simple precipitation method and characterized via various techniques. Experiments investigating the effect of contact time, pH, LZH dose, initial phosphate concentration, and co-existing ions on phosphate adsorption were conducted. LZH exhibited a high phosphate adsorption capacity (135.4 mg g -1 ) at a neutral pH. More than 50% of phosphate was removed within the first 60 s of contact time at an initial phosphate concentration of 5 mg L -1 . Phosphate removal using the as-prepared LZH adsorbent was also tested in real treated sewage effluent reducing the residual phosphate amount to levels inhibiting to the growth of algae. Furthermore, phosphate desorption from LZH was investigated using acetic acid and sodium hydroxide regenerants which showed to be very effective for phosphate recovery.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Fatty acid foams for nonselective physical removal of microplastics from aqueous solutions

Microplastics (MPs) are pervasive environmental contaminants whose removal from water remains a major challenge due to their small size, chemical diversity, and dynamic surface properties arising from environmental aging/weathering. Here, we present a concept of foam-based separation method that physically traps MPs in the foam phase using microtubular assemblies of 12-hydroxystearic acid. These foams are stabilized by anisotropic fatty acid microtubules formed in the presence of ethanolamine, which jam within the foam channels and suppress fluid drainage thereby enhancing MP retention and foam stability. MPs of different sizes, polymer compositions (including polystyrene, polypropylene, polyethylene terephthalate, and polytetrafluoroethylene), and weathered states were retained in the foam phase without requiring chemical modification or relying on chemical interactions between the fatty acid and MPs. Thermally induced transition of the fatty acid microtubules into nanomicelles above the characteristic phase transition temperature (∼35 °C) enables controlled foam collapse and recovery of trapped MPs. The cumulative removal efficiency can exceed 85% through multiple foaming cycles, matching predictions from a probabilistic retention model. This work shows that foams can provide a simple platform to trap MPs, thus providing a new physical-removal strategy that does not rely on the particles’ chemistry.

Guillot, Kennedy A. [Louisiana State Univ., Baton ↗
DOE OSTI2022

Restored Passivation after Complete Removal of Front Poly-Si Between the Grid in Poly-Si/SiO2 Front/Back Cells

This work explores the use of wet chemical etching to completely remove the front poly-Si layer between grid lines of a front/back poly-Si/SiO2 passivated contact device. The purpose of the work is to provide excellent passivation under the metal grid, but to also maximize Jsc by eliminating optical absorption in the front poly-Si. We show that after a high temperature anneal to distribute carriers in the poly-Si/SiO2/c-Si interface all of the poly-Si can be removed selectively with TMAH, using the SiO2 as an etch-stop layer. The etched surface can be repassivated back to its original level with the addition of a SiNx/Al2O3 stack grown on the preserved tunnelling oxide layer followed by a short forming gas anneal. Using symmetric 100 - 200 nm intrinsically doped poly-Si/SiO2 on textured n-type wafer templates we show absolute device efficiency enhancement from 15% to 21% by increasing the Jsc by 12 mA/cm2 after removing the front poly-Si and repassivating while effectively preserving the Voc, and FF of the device. IQE values are similar to PERC devices in the short wavelength range.

etching↗
DOE OSTI2022

Tin removal by an annular surface wave plasma antenna in an extreme ultraviolet lithography source

Tin contamination of the collector mirror surface remains one of the crucial issues of EUV (Extreme Ultraviolet) sources, directly impacting the availability of the tool. Hydrogen plasma-based tin removal processes employ hydrogen radicals and ions to interact with tin deposits to form gaseous tin hydride (SnH 4 ), which can be removed through pumping. An annular surface wave plasma (SWP) source developed at the University of Illinois—Urbana Champaign is integrated into the cone and perimeter of the collection mirror for in situ tin removal. The SWP is characterized by high ion and radical densities, low electron temperature, and local generation where etching is needed. This method has the potential to significantly reduce downtime and increase mirror lifetime. Radical probe measurements show hydrogen radical densities in the order of 10 19 m -3 , while Langmuir probe measurements show electron temperatures of up to 6 eV and plasma densities on the order of 10 17–18 m -3 . The generated ions are essential to the tin cleaning and have sufficiently low energy to cause no damage to the collector capping layer. Tin etch rates of up to 270 nm/min were observed in a variety of experimental conditions, including various powers, pressures, flowrates, and temperatures. In conclusion, the high etch rates demonstrated in this study exceed the expected contamination rate of the EUV source.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

An Application of Molecular Recognition for the Efficient Removal of Cesium from Hanford Nuclear Waste by Modular Solvent Extraction

In this work, experimental results leading to flowsheet design are presented showing how a calixarene-crown ether based solvent-extraction process can meet the challenge of cesium removal from nuclear tank wastes stored at the US Department of Energy Hanford site. Cleanup of legacy Cold War nuclear waste stored in underground tanks represents one of the greatest environmental challenges facing the US Department of Energy in terms of risk, cost, and effectiveness of applicable science and technology. Planning for the cleanup at the Hanford Site calls for the removal of the radioactive fission product 137Cs from its alkaline salt waste, including the use of modular processes that can be deployed near the tank farms. To meet the resulting need for extremely high selectivity, the Next-Generation Caustic-Side Solvent Extraction (NG-CSSX) process employing a calix[4]arene-crown ether in modified kerosene has been adapted to remove sub-millimolar cesium in competition with molar sodium and potassium in a high-nitrate alkaline matrix. Potassium loading in the solvent was determined in extraction, scrubbing, and stripping, leading to an empirical model closely approximating cesium distribution ratios for a variety of Hanford waste types. Process chemistry has been developed based on this molecular-recognition approach, focusing on the competitive effect of potassium loading and the mitigating process modifications needed, including extending the scrub section. The result is a modular flowsheet design that can achieve cesium decontamination factors well in excess of 15,000 even for the worst-case Hanford waste.

Williams, Neil [ORNL] (ORCID:000000023159226X)↗
DOE OSTI2020

Halo removal experiments with hollow electron lens in the BNL Relativistic Heavy Ion Collider

A hollow electron beam has been proposed as an active control tool to remove the beam halo from high-energy, high-current hadron or ion machines (such as the High-Luminosity Large Hadron Collider). To study the halo removal rate and assess the effect on the ion beam core, one of the two electron lenses in the Relativistic Heavy Ion Collider was changed from a Gaussian beam profile to a hollow profile. We describe the design and verification of the hollow electron beam parameters as well as the methods to minimize the hollow beam profile distortions, which can result in an ion beam emittance increase. The hollow beam alignment with the ion beam by using a backscattered electron detector has been demonstrated. Furthermore, experiments were carried out to explore the efficiency of the halo removal by scanning the current and inner radius of the hollow electron beam, which is pulsed either every turn or every nth turn. The effects of the hollow electron beam on the ion beam emittance and luminosity were also assessed experimentally by scanning the inner radius of the electron beam.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Angular Momentum Removal by Neutron and γ-Ray Emissions during Fission Fragment Decays

In this work, we investigate the angular momentum removal from fission fragments (FFs) through neutron and γ-ray emission, finding that about half the neutrons are emitted with angular momenta ≥ 1.5 ℏ and that the change in angular momentum after the emission of neutrons and statistical γ rays is significant, contradicting usual assumptions. Per fission event, in our simulations, the neutron and statistical γ-ray emissions change the spin of the fragment by 3.5 – 5 ℏ , with a large standard deviation comparable to the average value. Such wide angular momentum removal distributions can hide any underlying correlations in the fission fragment initial spin values. Within our model, we reproduce data on spin measurements from discrete transitions after neutron emissions, especially in the case of light FFs. The agreement further improves for the heavy fragments if one removes from the analysis the events that would produce isomeric states. Finally, we show that while in our model the initial FF spins do not follow a sawtoothlike behavior observed in recent measurements, the average FF spin computed after neutron and statistical γ emissions exhibits a shape that resembles a sawtooth. This suggests that the average FF spin measured after statistical emissions is not necessarily connected with the scission mechanism as previously implied.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Removal of radon progeny from delicate surfaces

210 Po α-decay-driven neutron background is a concern for many rare event search experiments. It is a difficult to control background because its radiogenic component depends on the air exposure history of parts. In this study, we demonstrate that about half of the radon progeny 210 Po can be removed from copper and silicon surfaces relatively easily by wiping a copper sample with acetone-wetted tissue and a silicon detector with acetone soaked cotton balls. For a copper sample, we demonstrate that long-lived 210 Pb is removed with similar effectiveness. For copper, allocated the longest counting time, additional wiping was found to be largely ineffective. For silicon, the removal effectiveness has large uncertainties. Additional cleaning showed a small but statistically significant effect. Here, capitalizing on this trivial cleaning step will allow experiments to relax their requirements on the allowable air exposure time during construction, leading to cost and time savings.

Radioactivity↗
DOE OSTI2024

The Science, Engineering, and Validation of Marine Carbon Dioxide Removal and Storage

Scenarios to stabilize global climate and meet international climate agreements require rapid reductions in human carbon dioxide (CO 2 ) emissions, often augmented by substantial carbon dioxide removal (CDR) from the atmosphere. While some ocean-based removal techniques show potential promise as part of a broader CDR and decarbonization portfolio, no marine approach is ready yet for deployment at scale because of gaps in both scientific and engineering knowledge. Marine CDR spans a wide range of biotic and abiotic methods, with both common and technique-specific limitations. Further targeted research is needed on CDR efficacy, permanence, and additionality as well as on robust validation methods—measurement, monitoring, reporting, and verification—that are essential to demonstrate the safe removal and long-term storage of CO 2 . Engineering studies are needed on constraints including scalability, costs, resource inputs, energy demands, and technical readiness. Research on possible co-benefits, ocean acidification effects, environmental and social impacts, and governance is also required.

climate mitigation↗
DOE OSTI2026

An Acid-Free, Temperature-Based Cation Contamination Removal Strategy for PEM Water Electrolysis

It is widely understood that the durability and reliability of polymer electrolyte membrane (PEM) water electrolyzers are heavily dependent on feedwater purity, with cation contaminants that originate from incomplete water purification and balance of plant materials significantly harming electrolyzer performance. However, contamination remains a challenge and a common cause of failure at the stack level, indicating the need for strategies to recover the performance of contaminated cells. In this study, we investigate the effects of temperature on the uptake, electrochemical impacts, and removal of contaminant calcium and iron cations. Lower operating temperatures increase the sensitivity of the cell performance to contaminant cations, while also decreasing cation uptake and promoting contaminant removal. Computational charge transfer modelling shows that lower temperature increases the concentration of contaminant at the cathode and facilitates their removal from the cell. By testing single cells under scenarios designed to mimic stack temperature dynamics, we investigate low-temperature operation as an approach to stack-relevant contaminant recovery. Together, these results demonstrate that the low-temperature recovery approach is a promising approach for acid-free contamination recovery for PEM water electrolysis to promote stack reliability and durability.

08 HYDROGEN↗
DOE OSTI2024

Preliminary Study of Iodine Gas Removal in Sodium Pools

Potential iodine gas release from failed fuel pins is a critical factor in the source term analysis of oxide fuel-loaded sodium fast reactors (SFRs). The accumulated iodine-containing gas mixtures inside pin plenums are expected to be ejected during pin failures and rise through sodium pool, with potential release of gaseous iodine to the cover gas region. Due to its potential radiological impacts, a proper assessment of iodine behavior is necessary for an accurate source term assessment. Throughout the bubble rise trajectory in the sodium pool, iodine gas is continuously removed or transformed at the bubble interface by diffusion, as the combining reaction between the iodine and sodium to form sodium iodide (NaI) is a chemically preferred process. As the final amount of iodine released from the facility is strongly influenced by the removal phenomenon inside the sodium pool, experiments were previously performed by PNC (Power Reactor and Nuclear Fuel Development Corporation) to provide insight into this phenomenon. To assess the accuracy of present methods for predicting iodine gas removal within sodium pools, several candidate approaches, available in source term analysis codes, have been summarized and evaluated in this study. Spherical cap bubbles and spherical bubbles are considered in accordance with the methods adopted in each approach, and different forms of correlations for major parameters have been implemented in accordance with the original adoptions. Based on the summarized results, important aspects to be considered have been derived.

Decontamination↗
DOE OSTI2022

Electron beam treatment for the removal of 1,4-dioxane in water and wastewater

Electron beam (e-beam) treatment uses accelerated electrons to form oxidizing and reducing radicals when applied to water without the use of external chemicals. In this study, electron beam treatment was used to degrade 1,4-dioxane in several water matrices. Removal improved in the progressively cleaner water matrices and removals as high as 94% to 99% were observed at a dose of 2.3 kGy in secondary effluent. 1,4-dioxane removal was confirmed to be primarily through hydroxyl radical oxidation. The calculated electrical energy per order was found to be 0.53, 0.26, and 0.08 kWh/m 3 /order for secondary effluent (Avg. total organic carbon (TOC) 9.25 mg/L), granular activated carbon effluent (TOC 3.46 mg/L), and ultrapure water, respectively, with a 70% generation and transfer efficiency applied.

1,4-dioxane↗
DOE OSTI2024

Factorial experiment to identify two-way interactions between temperature, harvesting period, hydraulic retention time, and light intensity that influence the biomass productivity and phosphorus removal efficiency of a microalgae–bacteria biofilm

Rotating algae biofilm reactors (RABRs) can reduce energy requirements for wastewater reclamation but require further optimization for implementation at water resource recovery facilities (WRRF). Optimizing RABR operation is challenging because conditions at WRRF change frequently, and disregarding interaction terms related to these changes can produce incorrect conclusions about RABR behavior. This study evaluated the two-way interaction and main effects of four factors on the biomass productivity and phosphorus removal efficiency of a microalgae-bacteria biofilm grown in municipal anaerobic digester centrate, with factor levels and operating conditions selected to mimic a pilot RABR at a WRRF in Utah. Two-way interactions harvesting period*light intensity (LI), harvesting period*temperature, and LI*hydraulic retention time (HRT) had significant effects on biomass productivity: at high temperature and low LI, highest biomass productivity was achieved with a 14-day harvesting period, but at medium temperature and high LI, highest biomass productivity was achieved with a 7-day harvesting period. At high HRT, highest biomass productivity occurred at low LI, but at low HRT, highest biomass productivity occurred at high LI. Phosphorus removal was strongly influenced by LI and occurred most rapidly during the first 2 days HRT, which suggests precipitation contributed significantly to phosphorus removal. These observations provide insight for further RABR optimization.

09 BIOMASS FUELS↗
DOE OSTI2020

Cesium Removal Performance Comparisons of Crystalline Silicotitanate Media Batches with Savannah River Site Waste Simulant

The Tank Closure Cesium Removal (TCCR) system uses ion exchange columns filled with Crystalline Silicotitanate (CST) media to process radioactive waste solutions for the removal of Cs- 137. The TCCR project is currently focused on dissolving Savannah River Site (SRS) Tank 10H waste (primarily sodium salt cake solids) within the tank followed by at-tank ion exchange column treatment. Plans are underway to prepare and install a second TCCR unit at SRS. Capacity and particle size differences exist between archived (IE-911) and more recently prepared CST media batches (9120-B and 9140-B). Side-by-side comparison testing was performed to evaluate the cesium removal performance of each batch to aid in selecting the preferred CST batch and media characteristics to load into the second TCCR unit. Batch contact equilibrium and flow-through column tests have been conducted with three CST batches using an SRS Average Simulant.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Summary of Expedited Results from Samples Supporting Tank Closure Cesium Removal (TCCR) Batch 3

Savannah River Remediation (SRR) is currently operating the Tank Closure Cesium Removal (TCCR) process to remove 137 Cs from tank waste supernate using an ion exchange process. As part of that process, Savannah River National Laboratory (SRNL) receives and analyzes samples in support of the qualification of each batch to be processed. SRNL recently received supernate samples retrieved from Tank 10H as well as in-tank batch contact samples for characterization in support of qualifying Batch 3 for processing through the TCCR unit. SRNL received and characterized a set of dip samples collected from Tank 10H (one surface and one variable depth sample). No solids were observed in either sample and therefore the samples were combined, and a suite of analyses were performed on the composite sample. The density of the combined sample was 1.174 g/mL (0.18 %RSD), which was consistent with the measured sodium concentration of 3.54 M (0.08 %RSD). The 137Cs activity in the sample was 4.75E+07 dpm/mL (4.28 %RSD) and the total Cs concentration was calculated to be 1.54 mg/L (1.16E-05 M). The in-tank batch contact samples consist of 0.1 g of crystalline silicotitanate (CST) contained within a teabag device. Duplicate samples were submerged in Tank 10H supernate for a period of about 13 days, after which time they were retrieved and transferred to SRNL for analysis. At SRNL the CST was rinsed to remove excess salt solution and the CST was then air dried before being digested for analysis. Results of the analysis indicated a 137 Cs loading of 3.66E+10 ± 1.40E+09 dpm/g or 16.5 ± 0.63 Ci/kg CST . This value represents a bounding upper limit as it includes the addition of two sigma uncertainty from replicate analysis of the individual teabag samples as well as the addition of the small amount of 137 Cs activity measured in the rinse solutions. The above values are based on the air-dried mass of CST. Correcting to the true dry mass using a F-factor of 0.8191 results in a maximum loading of 20.2 ± 0.77 Ci/kg CST .

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Removal of High Specific Activity Fission Products from Uranyl Sulfate Waste Solutions

The Savannah River National Laboratory (SRNL) is currently providing support to SHINE Medical Technologies (SHINE) which plans to deploy a low energy, accelerator-based neutron source to fission low enriched U in a uranyl sulfate target solution for 99 Mo production. The 99 Mo is initially separated from the fission products and target solution by an extraction column. Subsequent washing of the column will generate waste solutions containing residual U and fission product activity. A small number of high specific activity fission products (e.g., 90 Sr, 137 Cs, and 144 Ce) in these streams will likely control the classification of the low level waste (LLW). If a sufficient amount of the high specific activity isotopes are separated from the SHINE waste streams and concentrated into a waste form, it would be possible to treat a majority of the wash solutions from the column operations as a lower class of LLW (Class A versus Class B or C or Class B versus Class C). The high specific activity fission product elements could then be dispositioned as a much smaller volume of waste rather than requiring the disposal of the entire waste stream at the higher waste classification. The Savannah River Site (SRS) has experience with using monosodium titanate (MST) and crystalline silicotitanate (CST) to remove Cs and Sr from high salt content waste solutions generated during the reprocessing of nuclear fuels and targets. Both of these materials have worked very well for their intended purposes at the SRS where the fission product elements are removed from highly alkaline waste. On the other hand, SHINE waste streams from the extraction column contain H 2 SO 4 which makes the solution acidic. Additionally, the SRS waste streams do not contain other fission product elements such as transition metals or lanthanides because they precipitate upon neutralization of the SRS waste and are not present in the supernate which is dispositioned as LLW following treatment. As such, there are inherent differences between SHINE and SRS waste treatment strategies. Savannah River National Laboratory was tasked with performing scoping studies to see if MST and CST would remove Sr, Cs, and Ce from an acidic mixed metal simulant solution. Batch contact experiments were performed using MST and two CST type materials. The MST material is a 15 wt % powder in 0.15 M NaOH slurry. The MST showed low adsorption for elements of interest from acidic solution. Furthermore, the powder size makes MST non-ideal for column operations. A CST IE-911 ion exchange material had high Cs adsorption, moderate Sr, and marginal Ce adsorption. Based on adsorption of all species, the ion exchange capacity was found to be 0.032 meq/mL. A bench-top column experiment to measure elemental breakthrough curves was performed using CST IE-911 where chromatographic separations of the mixed simulant were expected to occur. While most elements behaved as expected, the lanthanide series, containing Ce, broke though the column earlier than expected. The second CST material, CST R9120, displayed high adsorption for all elements in the acidic mixed simulant solutions in a batch contact study, and had a calculated loading capacity of 0.091 meq/mL. Future studies to develop a waste treatment flowsheet should focus on CST R9120 to treat SHINE waste solutions.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Epoxy / Silicone Potting Material Removal for Greater Recovery of Circuit Boards

This report documents an exploratory research project, “Epoxy/Silicone Potting Material Removal for Greater Recovery of Circuit Boards,” that investigated micro abrasion and laser ablation as potential cost effective methods for removal of epoxy and silicone potting material from printed circuit boards (PCBs) to expose components for testing and repair. The ability to cost effectively remove such PCB potting materials will improve PCB repair, remanufacture, and reuse opportunities with potential for sizable reductions in material use, E-waste, and energy. Laser ablation was identified as a method potentially warranting further investigation, in particular for epoxy based potting materials.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗