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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 1,675 records · Page 93

Vibrations of a Fluid Containing a Wide Spaced Net with Floats Under Its Free Surface

We consider the problem of low-frequency vibrations of a heavy viscous incompressible fluid occupying a vessel. Under the free surface of the fluid, there is a wide spaced net with floats forming a nonperiodic structure. On the walls of the vessel and the surface of the floats the adhesion condition (zero Dirichlet condition) is imposed. For this problem, which is formulated in terms of a quadratic operator pencil, we construct a limit (homogenized) pencil and establish a homogenization theorem in the case of a “fairly small” number of floats. It is shown that asymptotically, this structure does not affect free vibrations of the fluid.

42 ENGINEERING↗

Enhanced high-temperature tensile property by gradient twin structure of duplex high-Nb-containing TiAl alloy

A pre-deformation process was employed for a TiAl alloy via high-temperature torsion, in which the stability of the constituent phases was tailored, resulting in enhanced hardening capability and ductility via a gradient microstructure. A sample with a pre-torsion of 360° exhibited a yield strength of 475 MPa and an ultimate tensile strength of 592 MPa, with a tensile ductility of 47% at 850 °C. The tensile properties were significantly enhanced compared with the as-forged sample, which exhibited values of 395 MPa, 494 MPa, and 4.6%, respectively. The physical mechanisms for the significant enhancement of the mechanical property of the TiAl alloys were studied in-depth via of transmission electron microscopy, electron-backscattered diffraction, and high-energy X-ray diffraction techniques. The high strength is mainly attributed to the twin structure formed during torsion, while high fracture elongation correlates to the recrystallization of the γ phase at twin-twin sections and the load partitioning regulated by a hierarchical microstructure. When the tensile micro-strains along the loading direction and transverse direction in the γ phase of the pre-deformed TiAl alloy, a higher mechanical performance was obtained. Moreover, the fracture mode of the pre-torsional tensile sample is a combination of pores and cleavage facets which resulted from the microstructure after torsion. Finally, the gradient twin structure approach in this study provides a strategy for developing TiAl alloys with exceptionally high-temperature tensile property, and the results of the micromechanical behavior-microstructure-property relationship may improve the understanding of the plastic deformation of TiAl alloys.

36 MATERIALS SCIENCE↗

Energy efficiency evaluation of a stationary lithium-ion battery container storage system via electro-thermal modeling and detailed component analysis

Energy efficiency is a key performance indicator for battery storage systems. A detailed electro-thermal model of a stationary lithium-ion battery system is developed and an evaluation of its energy efficiency is conducted. The model offers a holistic approach to calculating conversion losses and auxiliary power consumption. Sub-models for battery rack, power electronics, thermal management as well as the control and monitoring components are developed and coupled to a comprehensive model. The simulation is parametrized based on a prototype 192 kWh system using lithium iron phosphate batteries connected to the low voltage grid. The key loss mechanisms are identified, thoroughly analyzed and modeled. Generic profiles featuring various system operation modes are evaluated to show the characteristics of stationary battery systems. Typically the losses in the power electronics outweigh the losses in the battery at low power operating points. The auxiliary power consumption dominates for low system utilization rates. For estimation of real-world performance, the grid applications Primary Control Reserve, Secondary Control Reserve and the storage of surplus photovoltaic power are evaluated. Conversion round-trip efficiency is in the range of 70-80%. Finally, overall system efficiency, which also considers system power consumption, is 8-13 percentage points lower for Primary Control Reserve and the photovoltaic-battery application. However, for Secondary Control Reserve, the total round-trip efficiency is found to be extremely low at 23% due to the low energy throughput of this application type.

25 ENERGY STORAGE↗

Oxidative Dissolution of UO2 in a Simulated Groundwater Containing Synthetic Nanocrystalline Mackinawite

The long-term success of in situ reductive immobilization of uranium (U) depends on the stability of U(IV) precipitates (e.g., uraninite) under oxic conditions. Field and laboratory studies have implicated iron sulfide minerals as redox buffers or oxidant scavengers that may slow oxidation of reduced U(VI) solid phases by oxygen and Fe(III). Yet, the inhibition mechanism(s) and reaction rates of uraninite (UO2) oxidative dissolution by oxic species such as oxygen in FeS-bearing systems remain largely unresolved. To address this knowledge gap, abiotic batch experiments were conducted with synthetic UO2 in the presence and absence of synthetic mackinawite (FeS) under simulated groundwater conditions of pH = 7, PO2 = 0.02 atm, and PCO2 = 0.05 atm (equivalent to total dissolved carbonate of 0.01 M). The kinetic profiles of dissolved uranium indicate that FeS inhibited UO2 dissolution for 51 hr by effectively scavenging oxygen and keeping dissolved oxygen (DO) low. During this time period, oxidation of structural Fe(II) and S(-II) of FeS were found to control the DO levels, leading to the formation of iron oxyhydroxides and elemental sulfur, respectively, as verified by X-ray diffraction (XRD), Mössbauer and X-ray absorption spectroscopy (XAS). After FeS was depleted due to oxidation, DO levels increased and UO2 oxidative dissolution occurred at an initial rate of rm = 1.2 ± 0.4 ×10-8 mol•g-1•s-1, higher than rm = 5.4 ± 0.3 ×10-9 mol•g-1•s-1 in the control experiment where FeS was absent. Soluble U(VI) products were adsorbed by iron oxyhydroxides (i.e. nanogoethite and ferrihydrite) formed from FeS oxidation, which facilitated the detachment of U(VI) surface complexes and more rapid dissolution of UO2. XAS analysis confirmed the adsorption of U(VI) species, and also showed that U(VI) was not significantly incorporated into iron oxyhydroxide structure. This work reveals that both the oxygen scavenging by FeS and the adsorption of U(VI) to FeS oxidation products may be important in U reductive immobilization systems subject to redox cycling events.

Containing↗

Plasma sprayed coatings for containment of Cu-Mg-Si metallic phase change material

In this study, the performance of Y 2 O 3 -stabilized ZrO 2 (YSZ), Y 2 O 3 , and Al 2 O 3 plasma sprayed coatings are investigated for their ability to prevent attack of Haynes 230 by a near-eutectic Cu-Mg-Si metallic phase change material (PCM) in a closed environment at 820 °C. Areas where coatings failed were identified with optical and scanning electron microscopy, while chemical interactions were clarified through elemental mapping using electron microprobe analysis. Despite its susceptibility to reduction by Mg, the Al 2 O 3 coating performed well while the YSZ and Y 2 O 3 coating showed clear areas of attack. These results are attributed to the evolution of gaseous Mg at 820 °C leading to the formation of MgO and MgAl 2 O 4 .

36 MATERIALS SCIENCE↗

Electrochemical Characterization and Catalytic Application of Gold-Supported Ferrocene-Containing Diblock Copolymer Thin Films in Ethanol Solution

This study reports the electrochemical behavior and catalytic property of electrode-supported thin films of polystyrene- block -poly(2-(acryloyloxy)ethyl ferrocenecarboxylate) (PS- b -PAEFc) in an ethanol (EtOH) solution. The electrochemical properties of PS- b -PAEFc films with different PAEFc volume fractions (f PAEFc = 0.47, 0.30, and 0.17) in 0.1 M ethanolic sodium hexafluorophosphate were compared with those in an acetonitrile (MeCN) solution of 0.1 M tetrabutylammonium hexafluorophosphate. Pristine PS- b -PAEFc films did not afford significant faradaic currents in the EtOH solution because EtOH is a nonsolvent for both PS and PAEFc. However, the films could be rendered redox-active in the EtOH solution by applying potentials in the MeCN solution to induce the redox-associated incorporation of the supporting electrolytes into the films. Atomic force microscopy images verified the stability of PAEFc microdomains upon electrochemical measurements in these solutions. Cyclic voltammograms measured in the EtOH solution for PS- b -PAEFc with the larger f PAEFc were diffusion-controlled regardless of ellipsometric film thickness (23 – 152 nm) at relatively slow scan rates, in contrast to those in the MeCN solution that were controlled by surface-confined redox species. The electron propagation efficiency in the EtOH solution was significantly lower than that in the MeCN solution due to the poorer swelling of the films, which limited the migration of counter ions and the collisional motions of the ferrocene moieties. PS- b -PAEFc films were applied as electrochemically-responsive heterogeneous catalysts based on the ferrocenium moieties for Michael addition reaction between methyl vinyl ketone and ethyl 2-oxocyclopentanecarboxylate (E2OC) in 0.1 M NaPF 6 /EtOH. The catalytic activities of thin films were similar regardless of f PAEFc , suggesting that the catalytic reaction took place for the reactants that could penetrate through the film and reach PAEFc microdomains communicable with the underlying electrode. Interestingly, the permeability of PS-b-PAEFc films provided a means to control the reaction selectivity, as suggested by negligible reaction of E2OC with trans -4-phenyl-3-buten-2-one.

36 MATERIALS SCIENCE↗

Recycled Cardboard Containers as a Low Energy Source for Cellulose Nanofibrils and Their Use in Poly(l-lactide) Nanocomposites

Cellulose nanomaterials have attracted a great deal of interest as sustainable alternatives to nonrenewable or fossil fuel-derived materials, particularly in composite applications. Cellulose nanofibrils (CNF) are most often derived from wood sources through energy-intensive and costly mechanical fibrillation processes. Here, recycled cardboard, referred to as old corrugated cardboard (OCC), was investigated as an alternate CNF source. OCC is a recycled material that can be obtained at one-tenth the cost of the commonly used bleached softwood Kraft pulp and can be refined to similar levels with nearly one-half of the energy consumption. Additionally, the distinct composition and morphology of OCC-derived CNF provides a more favorable fiber–matrix interface and better reinforcement capabilities of the cellulose nanofibrils in polymer matrices, displaying an over 70% increase in tensile modulus at a loading of 40 wt % with no decrease in tensile strength. When paired with biobased poly(l-lactide) (PLLA), OCC-derived CNF is proven to be an attractive low-cost and low-energy reinforcing agent for sustainable, high performance nanocomposites.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

WISE-CASING: Containment and Monitoring Institute (CaMI), Calgary, Canada FEM-DC Model

For the model calculation we applied EM3D using completion diagram of CaMI site and a background resistivity consistent with the borehole logs. It was also important to use the accurate position of the return electrode. We note that for the data fit the code also incorporated well casings for well INJ and the other observation well, either OB1 or OB2, in the calculation. In summary, we demonstrate here, for this particular case, that the DC results may be a reasonable approximation to the low frequency EM data collected at CaMI. If this approximation continues to hold, then the extreme computational efficiency offered by the hierarchical modeling used in the DC simulations will permit us to explore far more model complexity, especially the pervasive and troublesome data artifacts that arise when doing EM surveys in mature, culturally developed sites. In Brief, both the low frequency and DC simulation codes provided very consistent results that match the field data really well, indicating their capability to help monitoring borehole integrity with the low frequency EM method.

15 GEOTHERMAL ENERGY↗

Sampling Plan for Assaying Plates Containing Depleted or Normal Uranium

This paper describes the rationale behind the proposed method for selecting a 'representative' sample of uranium metal plates, portions of which will be destructively assayed at the Y-12 Security Complex. The total inventory of plates is segregated into two populations, one for Material Type 10 (depleted uranium (DU)) and one for Material Type 81 (normal [or natural] uranium (NU)). The plates within each population are further stratified by common dimensions. A spreadsheet gives the collective mass of uranium element (and isotope for DU) and the piece count of all plates within each stratum. These data are summarized in Table 1. All plates are 100% uranium metal, and all but approximately 60% of the NU plates have Kel-F{reg_sign} coating. The book inventory gives an overall U-235 isotopic percentage of 0.22% for the DU plates, ranging from 0.19% to 0.22%. The U-235 ratio of the NU plates is assumed to be 0.71%. As shown in Table 1, the vast majority of the plates are comprised of depleted uranium, so most of the plates will be sampled from the DU population.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Scoping Analysis of Source Term and Functional Containment Attenuation Factors

In order to meet future regulatory requirements, the Next Generation Nuclear Plant (NGNP) Project must fully establish and validate the mechanistic modular high temperature gas-cooled reactor (HTGR) source term. This is not possible at this stage in the project, as significant uncertainties in the final design remain unresolved. In the interim, however, there is a need to establish an approximate characterization of the source term. The NGNP team developed a simplified parametric model to establish mechanistic source term estimates for a set of proposed HTGR configurations.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Recovery Act: Adaptive Environmentally Contained Power and Cooling IT Infrastructure for the Data Center (Final Technical Report)

The objectives of this program were to research and develop a fully enclosed Information Technology (IT) rack system for 100 kilowatts (KW) of IT load that provides its own internal power and cooling with High Voltage Alternating Current (HVAC defined as 480 volt) and chilled water as the primary inputs into the system and accepts alternative energy power sources such as wind and solar. For maximum efficiency, internal power to the IT equipment uses distributed High Voltage Direct Current power (HVDC defined as 360-380 volt) from the power source to the IT loads. The management scheme aggressively controls energy use to insure the best utilization of available power and cooling resources. The solution incorporates internal active management controls that not only optimizes the system environment for the given dynamic IT loads and changing system conditions, but also interfaces with data center Building Management Systems (BMS) to provide a complete end-to-end view of power and cooling chain. This technology achieves the goal of a Power Usage Effectiveness (PUE) of 1.25, resulting in a 38% reduction in the total amount of energy needed to support a 100KW IT load compared to current data center designs.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Evaluation of the Likelihood for Thermal Runaway for Nitrate Salt Containers in Storage at Los Alamos National Laboratory

In order to handle and process the existing Los Alamos National Laboratory (LANL) Nitrate Salt drums it is necessary to quantify the risk. One of the most obvious dangers is a repeat of the original violent reaction (2015), which would endanger nearby workers, not only with radioactive contamination, but also with large amounts of heat, dangerous corrosive gases and the physical dangers associated with a bursting drum. If there still existed a high probability of violent reaction, then these drums should only be accessed remotely. The objective of the work reported herein is to determine the likelihood of a similar violent event occurring.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Advanced Borobond™ Shields for Nuclear Materials Containment and Borobond™ Immobilization of Volatile Fission Products - Final CRADA Report

Borobond is a company-proprietary material developed by the CRADA partner in collaboration with Argonne, and is based on Argonne's Ceramicrete technology. It is being used by DOE for nuclear materials safe storage, and Boron Products, LLC is the manufacturer and supplier of Borobond. The major objective of this project was to produce a more versatile composition of this material and find new applications. Major target applications were use for nuclear radiation shields, such as in dry storage casks; use in immobilization of most difficult waste streams, such as Hanford K-Basin waste; use for soluble and volatile fission products, such as Cs, Tc, Sr, and I; and use for corrosion and fire protection applications in nuclear facilities.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Review of Cementitious Materials Development and Applications That Have Supported DOE-EM Missions: Waste Treatment, Conditioning, Containment Structures, Tank Closures, Facility Decommissioning, Environmental Restoration, and Structural Assessments

The Department of Energy (DOE) is tasked with managing the legacy defense wastes that resulted from nuclear materials production and nuclear arms development. Nuclear-waste management encompasses generation, processing (treatment and packaging), storage, transport, and disposal. To date, there are over 100 million gallons of liquid radioactive and chemical mixed wastes within the Department of Energy complex as well as solid waste, debris, and environmental restoration media that require disposal. DOE has been able to meet the challenges involved in dispositioning this waste using unique technical approaches and application-specific data required due to the nature of the constituents to be managed (e.g., long-lived radionuclides and highly mobile radionuclides in the near surface environments). Cementitious materials have played a prominent role historically in the successful disposition of these wastes, in the reduction of risk to the public, and in the closure of decommissioned tanks and facilities across the DOE complex.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗