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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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Monolithically integrated InAs/InGaAs quantum dot photodetectors on silicon substrates
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Monolithic Kerr and electro-optic hybrid microcombs
Microresonator-based soliton generation promises chip-scale integration of optical frequency combs for applications spanning from time keeping to frequency synthesis. Access to the soliton repetition rate is a prerequisite for those applications. While miniaturized cavities harness Kerr nonlinearity and enable terahertz soliton repetition rates, such high rates are not amenable to direct electronic detection. Here, we demonstrate hybrid Kerr and electro-optic microcombs using a lithium niobate thin film that exhibits both Kerr and Pockels nonlinearities. By interleaving the high-repetition-rate Kerr soliton comb with the low-repetition-rate electro-optic comb on the same waveguide, wide Kerr soliton mode spacing is divided within a single chip, allowing for direct electronic detection and feedback control of the soliton repetition rate. Our work establishes an integrated approach to electronically access terahertz solitons, paving the way for building chip-scale referenced comb sources.
On the length scale and rate-dependent mechanical behavior of monolithic (oxy)sulfidic glassy solid-state electrolytes
In the controlled atmosphere of a dedicated glove box, nanoindentation performed with a diamond Berkovich indenter tip has been used to examine the mechanical behavior of three (oxy)sulfide solid-state electrolytes (SSEs), 70Li 2 S·(30–x)P 2 S 5 ·xP 2 O 5 (x = 0, 2, and 5). At a drive frequency of 120 Hz, the elastic modulus is found to be predominantly depth independent over the range of 100 nm to 1 μm and generally insensitive to the varying mol fraction of oxygen (0, 2, and 5%) as well as the imposed strain rates of 0.025, 0.05, and 0.1 1/s. All three SSEs exhibit significant room-temperature creep. Strain burst activity observed during loading (potentially representative of pore collapse or cracking) is attenuated with the addition of oxygen. The hardness is found to be insensitive to the imposed strain rates but varying with depth and oxygen content. Furthermore, the highest oxygen concentration yields the lowest hardness and strongest depth dependence.
Intelligent Integrated Machining: Ultrasonic Imaging for Assessment of Al-6061 Cladding Thickness in Monolithic U-10Mo Fuel Plates
Abstract not provided.
Low Enriched Uranium Core Design for the Massachusetts Institute of Technology Reactor (MITR) with Un-finned 12 mil-thick Clad UMo Monolithic Fuel
This report contains the results of reactor fuel element design for conversion of the Massachusetts Institute of Technology Reactor (MITR) from the use of highly enriched uranium (HEU) fuel to the use of low enriched uranium (LEU) fuel. The analyses were performed by staff members of the Global Threat Reduction Initiative (GTRI) Reactor Conversion Program at the Argonne National Laboratory (ANL) and the Massachusetts Institute of Technology Nuclear Reactor Laboratory. The core conversion to LEU is being performed with financial support of the U.S. government.
OPTIONS ANALYSES FOR BACK-END OF THE FUEL CYCLE FOR USHPRR U-MO MONOLITHIC FUEL
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Exploratory Project: Rigid nanostructured organic polymer monolith for in situ collection and analysis of plant metabolites from soil matrices
Plant metabolites released from litter leachates and root exudates enable plants to adapt and survive in a wide range of habitats by facilitating resource foraging and plant-organismal interactions, and could influence soil carbon storage. The biological functions of these plant inputs and the organismal interactions they facilitate in soil are strictly governed by their composition and molecular identity. Our current understanding about the molecular identity of exudates is based on physiological studies that are done in soil-less axenic cultures. On the other hand, ecological studies that rely on isotope labeling to track the fluxes of carbon from plants to soil have found the complexities of soil-microbe matrices as an insurmountable barrier to undertake any meaningful molecular level characterization of plant inputs. Although it is constantly advocated to undertake a molecular level identification of the dynamicity of plant metabolites in soils, the complexity of soil system has thus far prevented any such endeavors. We developed polymeric probes through in-situ polymerization of poly(styrene-co-vinylbenzyl chloride-co-divinylbenzene) to elucidate the chemical environment of the soil to which the plant roots are exposed. Hypercrosslinking of the polymeric probes through an in-situ Friedel-Crafts alkylation significantly increased the surface area and the sorption capacity of the probes. Surface functionalization of the probes using a hybrid approach was also attempted. The efficacy of these probes was tested using batch equilibration. Scanning electron microscopy revealed extensive modification of the surface of the probes through hypercrosslinking. The probes exhibited a lower site specific sorption (slope of Freundlich adsorption isotherm close to unity) and percent recovery of the sorbed compounds from the probes were >70, indicating a predominance of reversible sorption. Further we imparted specificity to this copolymer matrix by using molecular-template imprinting approach for the selective capture of less abundant plant metabolites from a crowded soil/litter leachate. Our results suggests that i) the root exudate pattern of plants is highly dependent on the nutrient status of the plant, with greater specificity of root exudation occurring in growing medium with low available form of nutrients, ii) the chemical composition of root exudation is a function of the distance of sampling from the source-roots, with the composition of root exudation being more enriched in polar metabolites farther from the source-roots, iii) Further we demonstrated that the compounds present in real root exudates diffuse farther from the source roots than those in artificial root exudates that are traditionally used. Thus, our project highlights how the soil matrix is instrumental in modifying the chemical composition of root exudates, and highlights that, apart from the plant physiology, the specificity and function of root exudates is also modified by environmental factors.
Plasma Sprayed Zirconium Diffusion Barrier Development for Monolithic U-Mo Metallic Fuels
This presentation discusses the DOE/NNSA Convert program and how plasma spray is implemented in nuclear fuel plate production.
Fuel Swelling and Creep Analysis for a MURR LEU U-10Mo Monolithic Plate
In this work, finite element analysis (FEA) is used to model and simulate the thermo-mechanical behavior of a selected LEU MURR fuel plate under typical irradiation conditions of the proposed LEU MURR core. The proposed LEU fuel element for MURR conversion has 23 curved fuel plates. The fuel element design and analysis are described in Reference [7]. The safety analysis for calculating the margin to flow instability that had elements with a mixture of burnups, which is typical for MURR operations. In addition to the application of engineering hot channel factors to account for variations in the fuel element manufacturing that could affect the coolant channel gaps, the analysis assumed a constriction of the coolant channel gaps due to an increase in the fuel plate thicknesses during the element lifetime. Estimates of the local plate thickness increase at end-of-life (EOL) due to fuel swelling and creep were developed from experimental data presented in References [8] and [9]. The maximum local plate thickness increase from that analysis was calculated for fuel plate 23 in an EOL element. Furthermore, the minimum margin to flow instability for the reference LEU cores was calculated to occur in coolant channel 23 of an EOL element, which is the coolant channel between plates 22 and 23. Therefore,the work performed here evaluated plate 23 only, as this was found to be the most limiting plate.
Direct Ink Writing of Void-Free Glass Monoliths
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Towards an IMEX Monolithic ALE Method with Integrated UQ for Multiphysics Shock-hydro
A number of critical science, engineering and advanced technology applications require predictive analysis of complex shock-hydrodynamics of fluid/solid materials with possible electromagnetic interaction. The physical mechanisms include wave-phenomena, material-transport, diffusion, chemical reactions, and electromagnetics. The highly nonlinear multiple-time and length-scale response of these mechanisms include discontinuities formed from shocks, contact surfaces, and complex tabular equations-of-state (EOS). Current dominant computational solution strategies use ad-hoc combinations of operator- splitting, semi-implicit, and explicit time-integration methods and decoupled nonlinear-solvers. While these approaches have enabled progress in forward simulation, the inherited mathematical structure has not provided stability, accuracy and efficiency to resolve all the dynamical time-scales of interest, nor has it enabled integrated fast sensitivity analysis and uncertainty quantification (UQ). This draft report describes initial progress towards developing a new multiphysics shock-hydro capability that is intended to be more robust, mathematically well-structured and can readily be combined with advanced higher-order implicit/explicit (IMEX) time integration and efficient adjoint-enhanced uncertainty quantification (UQ) techniques.
Monolithic Multigrid for a Reduced-Quadrature Discretization of Poroelasticity.
Abstract not provided.
Microstructural-Level Fuel Performance Modeling of U-Mo Monolithic Fuel
As the physics that governs the microstructural evolution of nuclear fuel span various time and spatial scales, to fully understand the fuel behavior inevitably involves atomic to mesoscale resolution that can be difficult to determine experimentally. Microstructural-level modeling and simulations can be used to develop physics-based materials models that can provide physical understanding to inform fabrication process control, as well as a valuable feedback mechanism between post-irradiation examination (PIE) results and fabrication parameters. In accordance with the program schedule, the primary goals of the microstructure modeling effort are to: 1. Address critical microstructural questions and provide practical guidance to the fabricator via the fuel product specification; 2. Provide mechanistic inputs for the existing fuel performance code to improve its descriptive and predictive capability at the macroscopic scale. In fiscal year (FY)-21, the work scope consisted of six main facets: (1) the effect of carbides on fuel performance; (2) gas diffusivity in different phases; (3) integration of microstructural fuel performance modeling; (4) property degradation; (5) irradiation creep; and (6) historical analysis of microstructure data. Brief summaries of each are included below.
An Algebraic Monolithic Method for Volume-coupled Multiphysics Problems.
Abstract not provided.
Monolithically Integrated GaN Nanoscale Air Channel Field Emission Diode and Transistor.
Abstract not provided.