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At least 1,711 records · Page 95
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Engineering Scale Drying of Aluminum-Clad Spent Nuclear Fuel: Experiment Report

Engineering-scale tests were performed to evaluate the relative effectiveness of forced gas and vacuum-drying processes on aluminum-clad spent nuclear fuel (ASNF) in preparation for extended dry storage. Drying models were developed to improve confidence in the likely range of conditions at the start of dry storage and to understand the factors most significant to each process. Testing was performed at the Holtec International Forced Helium Dehydration training facility in Camden, New Jersey, by students from the University of South Carolina in collaboration with Idaho National Laboratory. A full-size Type 1a basket, with a full-diameter vessel configuration (based on the Department of Energy standardized canister design), was used in combination with a 10 assembly surrogate ASNF arrangement to provide a proxy for geometry. A resistance heater incorporated in one assembly simulated the influence of 100 W decay heat. This instrumented chamber allowed testing of the removal of bulk water, physisorbed water, and chemisorbed water over a range of operating parameters with either drying process. Thick oxide films were grown on aluminum test plates to mimic the ASNF surface chemistry. These one-use test plates were housed within select assemblies during drying. Post-test analysis of these plates gave a measure of the moisture removed during each test, which was compared to a control. Instrumentation provided detailed thermal, humidity, and gas or pressure data relevant to each test. Model simulations generally compared favorably to instrument data for the tests. While both processes were able to remove bulk water, removal of chemisorbed water was shown to depend heavily on local temperature. To the disadvantage of vacuum drying, operations approaching or exceeding 220°C achieved consistently more dehydroxylation.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Gulf of Mexico blue hole harbors high levels of novel microbial lineages

Exploration of oxygen-depleted marine environments has consistently revealed novel microbial taxa and metabolic capabilities that expand our understanding of microbial evolution and ecology. Marine blue holes are shallow karst formations characterized by low oxygen and high organic matter content. They are logistically challenging to sample, and thus our understanding of their biogeochemistry and microbial ecology is limited. We present a metagenomic and geochemical characterization of Amberjack Hole on the Florida continental shelf (Gulf of Mexico). Dissolved oxygen became depleted at the hole’s rim (32 m water depth), remained low but detectable in an intermediate hypoxic zone (40–75 m), and then increased to a secondary peak before falling below detection in the bottom layer (80–110 m), concomitant with increases in nutrients, dissolved iron, and a series of sequentially more reduced sulfur species. Microbial communities in the bottom layer contained heretofore undocumented levels of the recently discovered phylum Woesearchaeota (up to 58% of the community), along with lineages in the bacterial Candidate Phyla Radiation (CPR). Thirty-one high-quality metagenome-assembled genomes (MAGs) showed extensive biochemical capabilities for sulfur and nitrogen cycling, as well as for resisting and respiring arsenic. One uncharacterized gene associated with a CPR lineage differentiated hypoxic from anoxic zone communities. Overall, microbial communities and geochemical profiles were stable across two sampling dates in the spring and fall of 2019. The blue hole habitat is a natural marine laboratory that provides opportunities for sampling taxa with under-characterized but potentially important roles in redox-stratified microbial processes.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1999

Precision Cleaning and Verification Processes Used at Marshall Space Flight Center for Critical Hardware Applications

Marshall Space Flight Center (MSFC) of the National Aeronautics and Space Administration (NASA) performs many research and development programs that require hardware and assemblies to be cleaned to levels that are compatible with fuels and oxidizers (liquid oxygen, solid propellants, etc.). Also, the Center is responsible for developing large telescope satellites which requires a variety of optical systems to be cleaned. A precision cleaning shop is operated with-in MSFC by the Fabrication Services Division of the Materials & Processes Division. Verification of cleanliness is performed for all precision cleaned articles in the Analytical Chemistry Branch. Since the Montreal Protocol was instituted, MSFC had to find substitutes for many materials that has been in use for many years, including cleaning agents and organic solvents. As MSFC is a research Center, there is a great variety of hardware that is processed in the Precision Cleaning Shop. This entails the use of many different chemicals and solvents, depending on the nature and configuration of the hardware and softgoods being cleaned. A review of the manufacturing cleaning and verification processes, cleaning materials and solvents used at MSFC and changes that resulted from the Montreal Protocol will be presented.

Caruso, Salvadore V.↗
NASA NTRS1978

An interpretation of special and general isotopic anomalies in r-process nuclei

My analysis of new discoveries by McCulloch and Wasserburg of Ba and Nd isotopic anomalies in inclusions of the Allende meteorite argues that (1) these anomalies contain special extinct radioactivities resulting from radioactive decay within grains formed in and ejected from the supernova interior, (2) the inclusions studied are fused assemblies of interstellar grains that were never totally vaporized, and (3) theoretical separation into r and s abundances suggests that fluctuations between r and s components has occurred during the accumulation processes. These points lend support to a new chemical picture of the early solar system that I have developed, although many interpretations remain possible. Measurements of the neutron-capture cross sections of Nd isotopes are urgently needed to experimentally validate these conclusions.

Clayton, D. D.↗
NASA NTRS2003

Research priorities and plans for the International Space Station-results of the 'REMAP' Task Force

Recent events in the International Space Station (ISS) Program have resulted in the necessity to re-examine the research priorities and research plans for future years. Due to both technical and fiscal resource constraints expected on the International Space Station, it is imperative that research priorities be carefully reviewed and clearly articulated. In consultation with OSTP and the Office of Management and budget (OMB), NASA's Office of Biological and Physical Research (OBPR) assembled an ad-hoc external advisory committee, the Biological and Physical Research Maximization and Prioritization (REMAP) Task Force. This paper describes the outcome of the Task Force and how it is being used to define a roadmap for near and long-term Biological and Physical Research objectives that supports NASA's Vision and Mission. Additionally, the paper discusses further prioritizations that were necessitated by budget and ISS resource constraints in order to maximize utilization of the International Space Station. Finally, a process has been developed to integrate the requirements for this prioritized research with other agency requirements to develop an integrated ISS assembly and utilization plan that maximizes scientific output. c2003 American Institute of Aeronautics and Astronautics. Published by Elsevier Science Ltd. All rights reserved.

NASA Center HQS↗
NASA NTRS1988

High-speed assembly language (80386/80387) programming for laser spectra scan control and data acquisition providing improved resolution water vapor spectroscopy

An assembly language program using the Intel 80386 CPU and 80387 math co-processor chips was written to increase the speed of data gathering and processing, and provide control of a scanning CW ring dye laser system. This laser system is used in high resolution (better than 0.001 cm-1) water vapor spectroscopy experiments. Laser beam power is sensed at the input and output of white cells and the output of a Fabry-Perot. The assembly language subroutine is called from Basic, acquires the data and performs various calculations at rates greater than 150 faster than could be performed by the higher level language. The width of output control pulses generated in assembly language are 3 to 4 microsecs as compared to 2 to 3.7 millisecs for those generated in Basic (about 500 to 1000 times faster). Included are a block diagram and brief description of the spectroscopy experiment, a flow diagram of the Basic and assembly language programs, listing of the programs, scope photographs of the computer generated 5-volt pulses used for control and timing analysis, and representative water spectrum curves obtained using these programs.

Allen, Robert J.↗
DOE OSTI2022

Versatile acid solvents for pristine carbon nanotube assembly

Chlorosulfonic acid and oleum are ideal solvents for enabling the transformation of disordered carbon nanotubes (CNTs) into precise and highly functional morphologies. Currently, processing these solvents using extrusion techniques presents complications due to chemical compatibility, which constrain equipment and substrate material options. Here, we present a novel acid solvent system based on methanesulfonic or p-toluenesulfonic acids with low corrosivity, which form true solutions of CNTs at concentrations as high as 10 g/liter (≈0.7 volume %). The versatility of this solvent system is demonstrated by drop-in application to conventional manufacturing processes such as slot die coating, solution spinning continuous fibers, and 3D printing aerogels. Through continuous slot coating, we achieve state-of-the-art optoelectronic performance (83.6 %T and 14 ohm/sq) at industrially relevant production speeds. This work establishes practical and efficient means for scalable processing of CNT into advanced materials with properties suitable for a wide range of applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Thermoplastic moulding of regenerated silk

Early insights into the unique structure and properties of native silk suggested that β-sheet nanocrystallites in silk would degrade prior to melting when subjected to thermal processing. Since then, canonical approaches for fabricating silk-based materials typically involve solution-derived processing methods, which have inherent limitations with respect to silk protein solubility and stability in solution, and time and cost efficiency. In this study, we report a thermal processing method for the direct solid-state moulding of regenerated silk into bulk ‘parts’ or devices with tunable mechanical properties. At elevated temperature and pressure, regenerated amorphous silk nanomaterials with ultralow β-sheet content undergo thermal fusion via molecular rearrangement and self-assembly assisted by bound water to form a robust bulk material that retains biocompatibility, degradability and machinability. This technique reverses presumptions about the limitations of direct thermal processing of silk into a wide range of new material formats and composite materials with tailored properties and functionalities.

36 MATERIALS SCIENCE↗
NASA NTRS2020

Technology Advancements for Channel Wall Nozzle Manufacturing In Liquid Rocket Engines

A regeneratively-cooled or dump-cooled nozzle is a critical component for expansion of hot gases to enable high temperature and performance in liquid rocket engines systems. Regeneratively-cooled channel wall nozzles are a design solution used across the propulsion industry as a simplified method to fabricate the nozzle structure with internal coolant passages. The scale and complexity of the channel wall nozzle (CWN) design can be challenging to fabricate which results in extended lead times and higher costs. Some of these challenges include: 1) Unique and high temperature materials, 2) Tight tolerances on large parts during manufacturing and assembly to contain high pressure propellants, 3) Thin-walled features to maintain adequate wall temperatures, and 4) Unique manufacturing process operations and complex tooling. The United States (U.S.) National Aeronautics and Space Administration (NASA) and U.S. specialty manufacturing vendors are maturing modern fabrication techniques to reduce complexity and decrease costs associated with channel wall nozzle manufacturing technology. Additive Manufacturing (AM) is one of the key technology advancements under evaluation for channel wall nozzles. Much of additive manufacturing for propulsion components has focused on laser powder bed fusion (L-PBF), but the scale is not yet feasible for application to large scale nozzles. NASA is evolving directed energy deposition (DED) techniques for nozzles including arc-based deposition, blown powder deposition, and Laser Wire Direct Closeout (LWDC). There are different approaches being considered for fabrication of the nozzle, and each of these DED processes offer unique process steps for rapid fabrication. The arc-based and blown powder deposition techniques are used for the forming of the CWN liner. A variety of materials are being demonstrated including Inconel 625, Haynes 230, JBK-75, and NASA HR-1. The blown powder DED process is also being demonstrated for forming an integral channel nozzle in a single operation in similar materials. The LWDC process is a method for closing out the channels within the liner and forming the structural jacket using a localized laser wire deposition technique. Identical materials mentioned above have been used for this process in addition to bimetallic closeout (C-18150–SS347, and C-18150–Inconel 625). NASA has completed process development, material characterization, and hot-fire testing on a variety of these channel wall nozzle fabrication technique. This publication presents an overview of the various channel wall nozzle manufacturing processes and materials under evaluation including results from the hot-fire testing. Future development and technology focus areas is also discussed relative to channel wall nozzle manufacturing.

Additive manufacturing↗
NASA NTRS2017

MSRR Rack Materials Science Research Rack

The Materials Science Research Rack (MSRR) is a research facility developed under a cooperative research agreement between NASA and the European Space Agency (ESA) for materials science investigations on the International Space Station (ISS). The MSRR is managed at the Marshall Space Flight Center (MSFC) in Huntsville, AL. The MSRR facility subsystems were manufactured by Teledyne Brown Engineering (TBE) and integrated with the ESA/EADS-Astrium developed Materials Science Laboratory (MSL) at the MSFC Space Station Integration and Test Facility (SSITF) as part of the Systems Development Operations Support (SDOS) contract. MSRR was launched on STS-128 in August 2009, and is currently installed in the U. S. Destiny Laboratory Module on the ISS. Materials science is an integral part of developing new, safer, stronger, more durable materials for use throughout everyday life. The goal of studying materials processing in space is to develop a better understanding of the chemical and physical mechanisms involved, and how they differ in the microgravity environment of space. To that end, the MSRR accommodates advanced investigations in the microgravity environment of the ISS for basic materials science research in areas such as solidification of metals and alloys. MSRR allows for the study of a variety of materials including metals, ceramics, semiconductor crystals, and glasses. Materials science research benefits from the microgravity environment of space, where the researcher can better isolate chemical and thermal properties of materials from the effects of gravity. With this knowledge, reliable predictions can be made about the conditions required on Earth to achieve improved materials. MSRR is a highly automated facility with a modular design capable of supporting multiple types of investigations. Currently the NASA-provided Rack Support Subsystem provides services (power, thermal control, vacuum access, and command and data handling) to the ESA developed Materials Science Laboratory (MSL) which accommodates interchangeable Furnace Inserts (FI). Two ESA-developed FIs are presently available on the ISS: the Low Gradient Furnace (LGF) and the Solidification and Quenching Furnace (SQF). Sample-Cartridge Assemblies (SCAs), each containing one or more material samples, are installed in the FI by the crew and can be processed at temperatures up to 1400 C. Once an SCA is installed, the experiment can be run by automatic command or science conducted via telemetry commands from the ground. This facility is available to support materials science investigations through programs such as the US National Laboratory, Technology Development, NASA Research Announcements, and others. TBE and MSFC are currently developing NASA Sample Cartridge Assemblies (SCA's) with a planned availability for launch in 2017.

Reagan, Shawn↗
NASA NTRS1986

Containerless processing of glass forming melts: D-1, MEA/A-2 experiment 81F01 conducted on STS-61A flight, October 1985

Results of experiment 81F01, which was conducted in the Material Experiment Assembly MEA/A-2 on the D-1 Spacelab Mission (STS-61A), are presented. The general plan of the experiment was to heat, melt, and quench six spherical samples of different glass forming compositions while they were levitated in a single axis acoustic levitator furnace (SAAL). In addition, two non-melting sintered alumina samples were used to check the operational characteristics of the SAAL under reduced gravity conditions. Three of the eight samples were levitated between 1250 and 1500 C before the lack of coolant created an over-temperature condition that caused the SAAL to shut down prematurely. Two of the three samples processed were calcia-gallia-silica and soda-lime-silica glass forming compositions. Evidence of a two to three times increase in the tendency for glass formation was obtained for the calcia-gallia-silica. The final glass appeared reasonably homogeneous even though it was made from hot pressed powders containing deliberate heterogeneities. A photographic record was obtained of the microgravity sample processing sequences.

Day, D. E.↗
DOE OSTI2021

Constitutive Model Development for Aging Polymer Encapsulants (ASC P&EM FY2021 L2 Milestone 7836)

This SAND report fulfills the completion requirements for the ASC Physics and Engineering Modeling Level 2 Milestone 7836 during Fiscal Year 2021. The Sandia Simplified potential energy clock (SPEC) non-linear viscoelastic constitutive model was developed to predict a whole host of polymer glass physical behaviors in order to provide a tool to assess the effects of stress on these materials over their lifecycle. Polymer glasses are used extensively in applications such as electronics packaging, where encapsulants and adhesives can be critical to device performance. In this work, the focus is on assessing the performance of the model in predicting material evolution associated with long-term physical aging, an area that the model has not been fully vetted in. These predictions are key to utilizing models to help demonstrate electronics packaging component reliability over decades long service lives, a task that is very costly and time consuming to execute experimentally. The initiating hypothesis for the work was that a model calibration process can be defined that enables confidence in physical aging predictions under ND relevant environments and timescales without sacrificing other predictive capabilities. To test the hypothesis, an extensive suite of calibration and aging data was assembled from a combination of prior work and collaborating projects (Aging and Lifetimes as well as the DoD Joint Munitions Program) for two mission relevant epoxy encapsulants, 828DGEBA/DEA and 828DGEBA/T403. Multiple model calibration processes were developed and evaluated against the entire set of data for each material. A qualitative assessment of each calibration's ability to predict the wide range of aging responses was key to ranking the calibrations against each other. During this evaluation, predictions that were identified as non-physical, i.e., demonstrated something that was qualitatively different than known material behavior, were heavily weighted against the calibration performance. Thus, unphysical predictions for one aspect of aging response could generate a lower overall rating for a calibration process even if that process generated better quantitative predictions for another aspect of aging response. This insurance that all predictions are qualitatively correct is important to the overall aim of utilizing the model to predict residual stress evolution, which will depend on the interplay amongst the different material aging responses. The DSC-focused calibration procedure generated the best all-around aging predictions for both materials, demonstrating material models that can qualitatively predict the whole host of different physical aging responses that have been measured. This step forward in predictive capability comes from an unanticipated source, utilization of calorimetry measurements to specify model parameters. The DSC-focused calibration technique performed better than compression-focused techniques that more heavily weigh measurements more closely related to the structural responses to be predicted. Indeed, the DSC-focused calibration procedure was only possible due to recent incorporation of the enthalpy and heat capacity features into SPEC that was newly verified during this L2 milestone. Fundamentally similar aspects of the two material model calibrations as well as parametric studies to assess sensitives of the aging predictions are discussed within the report. A perspective on the next steps to the overall goal of residual stress evolution predictions under stockpile conditions closes the report.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

Transforming any Facility for Meeting Strict Cleanliness Requirements

Over the life of the James Webb Space Telescope (JWST), Integration & Test (I&T) has taken place in areas that needed considerable work to make the facility itself and/or the protocols used while working in the rooms suitable to meet JWST percent area coverage (PAC) and molecular accumulation requirements. In addition to normal particulate matter, JWST had a uniquely significant challenge: fibers! Fibers not only cause much higher PAC levels, but they also risk damaging the angstrom sized Near Infrared Spectrometer (NIRSpec) microshutter array (MSA), which is critical to NIRSpec instrument performance. The primary emphasis of this paper is to address particulate and fiber contamination. The success of the JWST mission required effective cleanrooms, protocols, and mitigations in non-cleanroom areas that were pressed into service to house contamination-sensitive optics and scientific instruments. Some presented profound challenges. These included: NASA’s 60-year-old Johnson Space Center (JSC) Chamber A, which had never been used for anything contamination-sensitive, and the European tropical launch facilities, which were designed to meet International Standard Organization (ISO) Class 8 processing for communication satellites. The final challenge for JWST, as if to stare us in the face and say, “I dare you to try and make me clean enough,” was preparing the 4 areas in the Centre Spatial Guyanais (CSG) Final Assembly Building (BAF) located in French Guiana, a building in which one entire side opens for Ariane 5 rocket ingress and egress. This paper will describe our initial evaluation processes and the actual work undertaken to transform even the most challenging areas into first class cleanrooms that met JWST particulate and fiber requirements.

James Webb Space Telescope↗
NASA NTRS1979

Automated array assembly, phase 2

Tasks of scaling up the tandem junction cell (TJC) from 2 cm x 2 cm to 6.2 cm and the assembly of several modules using these large area TJC's are described. The scale-up of the TJC was based on using the existing process and doing the necessary design activities to increase the cell area to an acceptably large area. The design was carried out using available device models. The design was verified and sample large area TJCs were fabricated. Mechanical and process problems occurred causing a schedule slippage that resulted in contract expiration before enough large-area TJCs were fabricated to populate the sample tandem junction modules (TJM). A TJM design was carried out in which the module interconnects served to augment the current collecting buses on the cell. No sample TJMs were assembled due to a shortage of large-area TJCs.

Carbajal, B. G.↗
DOE OSTI2022

Catalyst layer formulations for slot-die coating of PEM fuel cell electrodes

The series of electrodes were fabricated by the scalable and manufacturable slot-die coating method for proton exchange membrane fuel cell (PEMFC) application. The inks with different amounts of solids were studied by rheological methods in order to establish a coating window with minimum manufacturing defects. The obtained electrodes were characterized by SEM, AFM, and optical microscopy, which showed that they were uniform and homogeneous with minimum defects. The electrochemical evaluation of the manufactured gas diffusion electrodes (GDE) showed that the main characteristics of the electrodes, like electrochemical surface area, proton resistivity, and double layer capacitance, were found to be close for all samples confirming the reproducibility of the slot-die process. Additionally, we studied the effects of membrane thickness on the performance of the GDE membrane electrode assemblies and determined that a decrease in membrane thickness favored the performance. Furthermore, the obtained results clearly demonstrated the applicability and feasibility of the approach for the Manufacturing of catalyst layers for the fuel cell application with potential for future mass production.

08 HYDROGEN↗
DOE OSTI2026

Pixelated plastic scintillator array manufacturing using fast-, photo-curable resin

Pixelated plastic scintillator arrays can serve as high efficiency and high resolution neutron imaging detectors. Manufacturing these arrays is intensive in both time and labor. This article presents a fabrication method based on additive manufacturing for two-dimensional plastic organic scintillator arrays using a custom-built automated assembly machine and a custom photocurable resin that has significant non-aromatic acrylate oligomer content. The process involves two main stages: fully autonomous production of one-dimensional layered arrays, followed by semi-autonomous cutting and stacking to form two-dimensional pixel arrays. One-dimensional arrays were manufactured at a rate of around 4 layers per hour with minimal defects and tight dimensional tolerances, while two-dimensional arrays up to 7 x 7 pixels and 70 mm in length were completed in approximately 3.5 hours. Final arrays exhibited dimensional deviations of less than 0.5 mm. Two-dimensional arrays read out by a multi-anode photomultiplier tube demonstrated per-pixel position resolution and pulse-shape discrimination, enabling gamma–neutron interaction separation in mixed radiation environments.

36 MATERIALS SCIENCE↗