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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 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Structure of tetragonal martensite in the In{sub 95.42}Cd{sub 4.58} cast alloy

The structure of martensite in the In{sub 95.42}Cd{sub 4.58} alloy has been studied by metallography, X-ray diffraction, dilatometry, and transmission electron microscopy. It has been shown that a massive structure built of colonies of tetragonal lamellar plates divided by a twin boundary {101}FCT is formed in the alloy under cooling below the martensite FCC → FCT transition temperature. The alloy recrystallizes after a cycle of FCT → FCC → FCT transitions with a decrease in the grain size by several times compared with the initial structure such fashion that the size of massifs and individual martensite lamella in the massif correlates with the change in the size of the alloy grain. Using thermal cycling, it has been revealed that the alloy tends to stabilize the high-temperature phase.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Analysis of Sample DUM002 (INL pin casting, 800C/48 hr, 500C 8 hr): Metallographic re-prep, FIB TEM foil extraction and (S)TEM analysis [Slides]

The scale of FIB foils versus the microstructure makes it likely that more than one feature of interest may be in each FIB foil prepared. Intergranular and intragranular silicides and carbides are present. It may be that the silicides are the more potent nuclea9on sites, by initial impressions without statistics. Non-statistical measurements of the lamellar spacing average approximately 300 to 500 nm. Measured U-Mo ratios via EDS were near expectations, even without the need for standards, simplifying analyses.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

Elevated and Low Temperature Deformation of Cast Depleted Uranium

Goals: Understand crystal structure and micro-structure changes during high and low temperature deformation of uranium, in particular texture, and develop constitutive micro-structure based model for uranium deformation. Deliverables achieved: Completed texture measures for 11 pre- and post-dU compression samples, quantified texture pre- and post-deformation, and provided data to constrain deformation models.

Materials Science(36)↗
DOE OSTI2017

Trace element control in binary Ni-25Cr and ternary Ni-30Co-30Cr master alloy castings

Electro-slag remelting (ESR) is used for control of unwanted elements in commercial alloys. This study focuses on master alloys of Ni-25Cr and Ni-30Co-30Cr, processed through a combination of vacuum induction melting (VIM) and electro-slag remelting (ESR). Minor additions were made to control tramp element levels and modify the melting characteristics. Nitrogen and sulfur levels below 10 ppm and oxygen levels below 100 ppm were obtained in the final products. The role of the alloy additions in lowering the tramp element content, the resulting residual inclusions and the melting characteristics were determined computationally and confirmed experimentally. Additions of titanium were beneficial to the control of oxygen levels during VIM and nitrogen levels during ESR. Aluminum additions helped to control oxygen levels during remelting, however, aluminum pickup occurred when excess titanium was present during ESR. The usefulness of these master alloys for use as experimental remelt stock will also be discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Laser Weld Geometry and Microstructure of Cast Uranium-6 wt% Niobium Alloy

Laser welding was performed on a U6 wt% Nb uranium alloy using a 400W solid state laser with welding speeds from 20 to 2,500 mm/s. This speed range spanned melt pool sizes from traditional welding to surface modification and additive manufacturing. With increasing scan speed, the ratio of weld length relative to depth and width increased, with melt pool lengths being more than 5x greater than the width and 10x greater than the depth at the highest speeds. Keyhole mode welds were shown to occur at low speeds, while conduction mode welds occurred at 700 mm/s or higher as the weld depth dropped off more rapidly than width at higher speeds. Microstructures that form at the boundary between the fusion zone and base metal were observed to have a nonconventional appearance consisting of interpenetrating dark and light contrast phases before cells or dendrites appear. Dendrites with secondary arms form from this boundary in keyhole welds and refine to no visible secondary arms near the weld center. Primary and secondary dendrite arms, where present, were shown to refine in size inversely with cooling rate raised to the 0.465 and 0.376 powers respectively. Dendrites were largely absent from the conduction mode welds at higher speeds, and were replaced by a banded microstructure, that appears to form by an oscillatory solidification front mechanism.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Uranium Casting Materials Development: HfN Testing Summary

A total of four dip tests were performed on TerraPower provided HfN coated niobium coupons. However, in the first two tests, excessive oxidation of the charges materials led to inadequate contact between the HfN coated specimens and the molten alloy. The final two tests used a much higher ramp rate, which provided less time for oxidation of the melt. In both of these tests, the dipped specimens appeared fully intact and coated with metal alloy. The alloy could not be easily removed, suggesting either a mechanical interlocking or a chemical bonding. Due to shifting programmatic priorities, metallographic examination of the samples was not performed.

36 MATERIALS SCIENCE↗
DOE OSTI2019

HALEU Decontamination Investigations for EBR-II Recovered Uranium. HALEU Drip Casting Results in the Fuel Conditioning Facility Cathode Processor

Many of the new advanced reactor designs being proposed by the nuclear private sector require uranium fuel enriched between 5 and 20%, otherwise known as High Assay Low Enriched Uranium (HALEU), to support their designs. There are currently no commercial facilities based in the United States which have the capability to produce this material, and as a result the nuclear industry has requested support from the Department of Energy (DOE) to meet this need. One approach being considered by DOE to respond to this demand is to recover highly enriched uranium from used nuclear fuels and downblend it to enrichments less than 20 % U-235. DOE’s past research related to liquid metal fast breeder reactors resulted in the irradiation of more than 3 metric tons (MT) of nuclear fuel composed of highly enriched metallic uranium which resides at the Idaho National Laboratory (INL). This inventory of used nuclear fuel is currently being conditioned using an electrometallurgical treatment process (EMT) to facilitate its eventual disposition to a geologic repository. As part of this treatment process, the highly enriched component of this used fuel is separated, recovered, downblended to <20% U-235, and stored as a metallic uranium ingot. The majority of this fuel was irradiated in the Experimental Breeder Reactor II (EBR-II) over the course of its 30 years of operation. This sodium cooled fast reactor utilized a core composed of highly enriched, sodium-bonded, metallic fuel to sustain or “drive” the reactor. This EBR-II driver fuel is currently being treated for sodium neutralization in the Fuel Conditioning Facility (FCF) at the Materials and Fuels Complex (MFC) and the metallic uranium recovered as a component of this process has been proposed as a potential source of supply of high assay low enriched uranium. The irradiation of the metallic uranium fuel results in the creation of fission products and some minor actinides which are not compatible with many reuse scenario’s, and introduces significant challenges associated with fabrication of new fuel elements using this material. However, it is believed that the current EMT process can be slightly enhanced to address these concerns and result in the recovery of a product that can be considered as a source of supply for HALEU applications. Based on this, DOE requested the INL research methods to enhance the EMT process to produce a recovered uranium material that has a lower contaminant level and lower radiological dose rate and could be utilized in glovebox based fuel fabrication scenarios. The report that follows documents the progress toward meeting this goal.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Progress and Technology Assessment of Melt-Cast Ceramic Waste Forms

The Savannah River National Laboratory (SRNL) conducted research from FY2011 – FY2020 to develop ceramic waste forms to treat High-Level Waste (HLW) resulting from reprocessing of commercial Used Nuclear Fuel (UNF) as part of the Department of Energy (DOE) office of Nuclear Energy (NE) Fuel Cycle Technologies (FCT) research program. The objective of the research was to develop a reference ceramic waste form and process technology needed to immobilize the combined HLW raffinate stream, including undissolved solids and soluble technetium, and potentially the TRU waste stream resulting from reprocessing processes. This report compiles the relevant literature produced under, and pertinent to, the program objectives and provides a perspective on the technology development as well as prospects for future.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

LEU-Mo Casting Update

The Y-12 National Security Complex (Y-12) participates in the Fuel Fabrication Pillar of the National Nuclear Security Administration’s (NNSA’s) Office of Material Minimization and Management (M3) Office of Conversion Pillar. Y-12’s primary responsibility is to establish the fabrication process for the low-enriched uranium-molybdenum (U-10Mo) feedstock.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Composite Cathode Architectures Made By Freeze-Casting for All Solid State Lithium Batteries (CRADA Final Report)

As part of a Battery 500 seedling project, MBRDNA partnered with LBNL and Montana State University (MSU) to develop solid-state batteries based on an Al-substituted LLZO (Li 7 La 3 Zr 2 O 12 ) ceramic ion-conductor. All solid-state lithium batteries are attractive contenders for use as power sources for electric vehicles because of their potential for better safety and higher energy density than state-of-the-art lithium-ion batteries, although they are still at early stages of development. Al-substituted LLZO is one of the most promising solid electrolytes for battery applications based on high ionic conductivity, a wide operating voltage window, and apparent stability vs. reduction by lithium. However, difficulties with processing thin (< 20 $\textit{um}$ and dense LLZO membranes have hampered development of devices based on this material. It is non-compressible and must be sintered at high temperatures to densify components. It is also difficult to maintain contact between the active cathode material and LLZO in the composite cathodes, which is critical for successful operation. This research project aimed to use novel processing methods to overcome these issues. The end result was the first ever-reported truly all solid-state battery based on LLZO operating at room temperature without application of exogenous pressure. During the course of the project, we also identified a number of issues that need to be addressed to improve the technology readiness level of this battery.

25 ENERGY STORAGE↗
DOE OSTI2024

Facilitating Implementation of High-Volume Fly Ash Use in Pre-cast Concrete Construction to Increase Beneficial Utilization

The main goal of this project was to increase the beneficial use of fly ash as a supplementary cementitious material for precast concrete applications. A major focus was to develop balanced concrete mix design strategies which collectively satisfy the follow objectives: 1) increase fly ash beneficial use by at least 15% in the precast concrete industry, 2) maintain or exceed stringent structural property requirements (e.g., compressive strength at initial prestress, modulus of rupture, etc.), 3) exhibit little or no additional cost relative to conventional mixtures, and 4) mitigate detrimental environmental consequences inadvertently caused by increased beneficial use. Outcomes from this project include recommendations for design guidelines and code provisions for sustainable concrete mix designs, facilitating diversion and harvesting of large quantities of fly ash from landfills or impoundments, and multiple frameworks for incorporating discarded fly ash materials (i.e., landfilled or ponded fly ash after separating the impurities) in concrete construction.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2024

CAST Technical Bulletin #004: Network Time Protocol Introduction

Network Time Protocol (NTP), as it traditionally generated and widely consumed, is a legacy system with known security vulnerabilities. The vulnerabilities can be mitigated by modern implementations of NTP that use internal and external redundancy for better accuracy and fault tolerance. Precision Time Protocol (PTP) is an alternative that uses master clocks inside secure networks to eliminate the known vulnerabilities of NTP.

24 POWER TRANSMISSION AND DISTRIBUTION↗