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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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10 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

A low-input strategy for chromium removal from industrial stormwater using peat sorbent

Low-cost and low-input water treatment systems are important for industrial stormwater remediation. Here we examine a flow-through reactor treatment installation where water exceeds the allowable maximum concentration for drinking water in multiple metals (e.g., chromium [Cr], cadmium [Cd], zinc [Zn]) prior to treatment. Specifically, we seek to understand why Cr attenuated in the reactors is not leachable by identifying the specific chemical form of Cr and dominant mechanisms promoting sequestration in the reactors. Total solid-phase Cr concentration in the peat media ranged from 50 to 150 mg/kg after 1 yr of exposure to stormwater to 300 to 900 mg/kg after 3.5 yr. X-ray fluorescence mapping images show Cr, iron (Fe), and Zn spatially correlated over a scale of 10 μm to 5 mm. Chromium rinds form on the edges of peat particles as Cr accumulates. Chromium and Fe K-edge X-ray absorption near edge structure spectroscopy reveal chromium predominately in the 3+ oxidation state with lesser amounts of elemental Cr. We propose the primary means of chromium attenuation in the reactors is precipitation as Cr-Fe hydroxides combined with trivalent Cr adsorption onto peat surfaces.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Analytical gradient-based optimization of CALPHAD model parameters

The calibration of CALPHAD (CALculation of PHAse Diagrams) models involves the solution of a very challenging high-dimensional multiobjective optimization problem. Traditional approaches to parameter fitting predominantly rely on gradient-free methods, which while robust, are computationally inefficient and often scale poorly with model complexity. In this work, we introduce and demonstrate a generalizable framework for analytic gradient-based optimization of the parameters of the CALPHAD model enabled by the recently formalized Jansson derivative technique. This method allows for efficient evaluation of gradients of thermodynamic properties at equilibrium with respect to model parameters, even in the presence of arbitrarily complex internal degrees of freedom. Leveraging these semi-analytic gradients, we employ the conjugate gradient (CG) method to optimize thermodynamic model parameters for four binary alloy systems: Cu-Mg, Fe-Ni, Cr-Ni, and Cr-Fe. Across all systems, CG achieves comparable or superior optimality relative to Bayesian ensemble Markov Chain Monte Carlo (MCMC) with improvements in computational efficiency ranging from one to three orders of magnitude. Furthermore, our results establish a new paradigm for CALPHAD assessments in which high fidelity data-rich model calibration becomes tractable using deterministic gradient-informed algorithms.

CALPHAD↗
DOE OSTI2023

FeCrAl fuel/clad chemical interaction in light water reactor environments

This article investigates the fuel-cladding chemical interaction (FCCI) behavior of two commercial FeCrAl alloys, APMT composition (Fe-21Cr-5Al-3Mo wt.%) and C35M (Fe-13Cr-5Al-2Mo-0.2Si-0.03Y wt.%), after neutron irradiation. “H-cup” diffusion multiples of FeCrAl alloys and ceramic UO 2 fuel were irradiated at a temperature of ~300 °C to a total estimated burnup of 26 GWd/tHM. Post-irradiation Examination results demonstrate the excellent degradation resistance of FeCrAl alloys as accident tolerant fuel (ATF) cladding materials in light water reactor conditions. The study concludes that there was no irradiation-induced defects observed in either of the two commercial FeCrAl claddings. The formation of amorphous Al/U mixed oxide was observed at the fuel-clad interface, which can serve as a tritium permeation barrier and protect against potential chemical attack from the fuel. Finally, the study attributed the formation of amorphous Al/U mixed oxide to the low temperature and limited time of neutron irradiation. APMT forms more distinct Cr and Cr-Fe intermetallic at the FeCrAl-UO 2 interface than C35M due to the higher bulk Cr:Al ratio.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS1990

Pristine moon rocks - An alkali anorthosite with coarse augite exsolution from plagioclase, a magnesian harzburgite, and other oddities

Results are presented on the analyses of 18 samples of pristine rocks obtained from the primarily mare Apollo 12 site and from the primarily highland Apollo 14 site, as well as samples from the nonmare Apollo 15 site. It was found that, while two of anorthosites from Apollo 12 were similar in composition to most other anorthosites from the west-central near region, the texture of an alkali anorthosite featured a long and narrow crystal of augite surrounded by a single crystal of plagioclase, clearly suggesting that the augite formed by exsolution out of the plagioclase. Another Apollo 12 rocklet was an unusual magnesian harzburite, with subequal amounts of enstatite and olivine, traces of Cr-Fe spinel, and FeNi metal, but no plagioclase; the bulk composition was found to be remarkably Ir-rich (53 percent) for a pristine rock, and the texture was also unusual. Apollo 14 samples included several uncommonly Al-rich and REE-poor impact melt breccias.

Warren, P. H.↗
DOE OSTI2020

Materials Data on Cr3Fe by Materials Project

Cr3Fe is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. there are two inequivalent Cr sites. In the first Cr site, Cr is bonded in a distorted body-centered cubic geometry to four equivalent Cr and four equivalent Fe atoms. All Cr–Cr bond lengths are 2.47 Å. All Cr–Fe bond lengths are 2.47 Å. In the second Cr site, Cr is bonded in a 8-coordinate geometry to eight equivalent Cr and six equivalent Fe atoms. All Cr–Fe bond lengths are 2.85 Å. Fe is bonded in a distorted body-centered cubic geometry to fourteen Cr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr3Fe by Materials Project

Cr3Fe is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Cr is bonded to eight equivalent Cr and four equivalent Fe atoms to form CrCr8Fe4 cuboctahedra that share corners with twelve equivalent CrCr8Fe4 cuboctahedra, edges with eight equivalent FeCr12 cuboctahedra, edges with sixteen equivalent CrCr8Fe4 cuboctahedra, faces with four equivalent FeCr12 cuboctahedra, and faces with fourteen equivalent CrCr8Fe4 cuboctahedra. All Cr–Cr bond lengths are 2.53 Å. All Cr–Fe bond lengths are 2.53 Å. Fe is bonded to twelve equivalent Cr atoms to form FeCr12 cuboctahedra that share corners with twelve equivalent FeCr12 cuboctahedra, edges with twenty-four equivalent CrCr8Fe4 cuboctahedra, faces with six equivalent FeCr12 cuboctahedra, and faces with twelve equivalent CrCr8Fe4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr3Fe by Materials Project

Cr3Fe is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Cr sites. In the first Cr site, Cr is bonded to eight equivalent Cr and four equivalent Fe atoms to form CrCr8Fe4 cuboctahedra that share corners with four equivalent CrCr8Fe4 cuboctahedra, corners with eight equivalent FeCr12 cuboctahedra, edges with twenty-four CrCr8Fe4 cuboctahedra, faces with six equivalent FeCr12 cuboctahedra, and faces with twelve CrCr8Fe4 cuboctahedra. All Cr–Cr bond lengths are 2.55 Å. All Cr–Fe bond lengths are 2.48 Å. In the second Cr site, Cr is bonded to eight Cr and four equivalent Fe atoms to form CrCr8Fe4 cuboctahedra that share corners with twelve equivalent CrCr8Fe4 cuboctahedra, edges with eight equivalent FeCr12 cuboctahedra, edges with sixteen CrCr8Fe4 cuboctahedra, faces with four equivalent FeCr12 cuboctahedra, and faces with fourteen CrCr8Fe4 cuboctahedra. All Cr–Cr bond lengths are 2.48 Å. All Cr–Fe bond lengths are 2.55 Å. Fe is bonded to twelve Cr atoms to form FeCr12 cuboctahedra that share corners with four equivalent FeCr12 cuboctahedra, corners with eight equivalent CrCr8Fe4 cuboctahedra, edges with eight equivalent FeCr12 cuboctahedra, edges with sixteen equivalent CrCr8Fe4 cuboctahedra, faces with four equivalent FeCr12 cuboctahedra, and faces with fourteen CrCr8Fe4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrFe3 by Materials Project

CrFe3 is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Cr is bonded in a distorted body-centered cubic geometry to fourteen Fe atoms. There are eight shorter (2.46 Å) and six longer (2.84 Å) Cr–Fe bond lengths. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 8-coordinate geometry to six equivalent Cr and eight equivalent Fe atoms. All Fe–Fe bond lengths are 2.46 Å. In the second Fe site, Fe is bonded in a distorted body-centered cubic geometry to four equivalent Cr and four equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrFe3 by Materials Project

CrFe3 is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Cr is bonded to twelve equivalent Fe atoms to form CrFe12 cuboctahedra that share corners with twelve equivalent CrFe12 cuboctahedra, edges with twenty-four equivalent FeCr4Fe8 cuboctahedra, faces with six equivalent CrFe12 cuboctahedra, and faces with twelve equivalent FeCr4Fe8 cuboctahedra. All Cr–Fe bond lengths are 2.52 Å. Fe is bonded to four equivalent Cr and eight equivalent Fe atoms to form FeCr4Fe8 cuboctahedra that share corners with twelve equivalent FeCr4Fe8 cuboctahedra, edges with eight equivalent CrFe12 cuboctahedra, edges with sixteen equivalent FeCr4Fe8 cuboctahedra, faces with four equivalent CrFe12 cuboctahedra, and faces with fourteen equivalent FeCr4Fe8 cuboctahedra. All Fe–Fe bond lengths are 2.52 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrFe by Materials Project

FeCr crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. Cr is bonded in a 12-coordinate geometry to four equivalent Cr and eight equivalent Fe atoms. All Cr–Cr bond lengths are 2.43 Å. There are four shorter (2.49 Å) and four longer (2.79 Å) Cr–Fe bond lengths. Fe is bonded in a 12-coordinate geometry to eight equivalent Cr and four equivalent Fe atoms. All Fe–Fe bond lengths are 2.43 Å.

36 MATERIALS SCIENCE↗