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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Separation of protactinium from uranium-niobium alloys for 231 Pa– 235 U radiochronometry in nuclear forensic investigations

The isolation and purification of protactinium from uranium materials is essential for 231 Pa– 235 U radiochronometry, but separating Pa from uranium-niobium alloys, a common material in the nuclear fuel cycle, is challenging due to the chemical similarity of Pa and Nb. Here, in this work, we present three resin chromatography separation techniques for isolating Pa from U and Nb which were independently developed by three different laboratories through ad hoc adaptations of standard operating procedures. Our results underscore the need for and value of purification methods suitable for a diversity of uranium-based materials to ensure the operational readiness of nuclear forensics laboratories.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

QCD resummation of dijet azimuthal decorrelations in pp and pA collisions

We study the azimuthal angular decorrelations of dijet production in both proton-proton (pp) and proton-nucleus (pA) collisions. By utilizing soft-collinear effective theory, we establish the factorization and resummation formalism at the next-to-leading logarithmic accuracy for the azimuthal angular decorrelations in the back-to-back limit in pp collisions. We propose an approach where the nuclear modifications to dijet production in pA collisions are accounted for in the nuclear modified transverse momentum dependent parton distribution functions (nTMDPDFs), which contain both collinear and transverse dynamics. This approach naturally generalizes the well-established formalism related to the nuclear modified collinear parton distribution functions (nPDFs). We demonstrate strong consistency between our methodology and the CMS measurements in both pp and pA collisions, and make predictions for dijet production in the forward rapidity region in pA collisions at LHC kinematics and for mid-rapidity kinematics at sPHENIX. Throughout this paper, we focus on the application of this formalism to a simultaneous fit to both collinear and transverse momentum dependent contributions to the transverse momentum dependent distributions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

A chromatography chemistry for purifying $\mathrm{Pa}$ from $\mathrm{U-Nb}$ metal alloys

Here we present a chromatography chemistry for purifying protactinium from uranium metal alloys containing weight-percent concentrations of niobium. Niobium is precipitated in 9 M HCl without the co-precipitation of Pa as demonstrated by gamma-ray spectrometry. Protactinium is further purified using Bio-Rad™ anion resin AG® 1-X8 and 9 M HCl + 0.0128 M HF. A Pa/Nb separation factor of 85,000 and a 90% Pa recovery is demonstrated, which is amenable to 231 Pa concentration determination by isotope dilution and 231 Pa/ 235 U model age calculation for nuclear forensics.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2024

Updated uranium reference material 231 Pa/ 235 U consensus model ages for nuclear forensics

Radiochronometry provides the model age of nuclear materials, which is useful for understanding the production history of materials found outside of regulatory control. Certified reference materials (CRMs) are important for radiochronometry to increase confidence in measurement quality; however, the absence of 231 Pa/ 235 U CRMs necessitates that nuclear forensic laboratories measure the 231 Pa/ 235 U model ages of preexisting uranium reference materials. Here, in this work, new consensus 231 Pa/ 235 U model ages are reported from three nuclear forensic laboratories for three reference materials using current analytical methods. These updated consensus values can be used for quality control of 231 Pa/ 235 U model age measurements.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Evaluation of material accountancy techniques for 233 Pa from thorium nuclear fuels

Thorium is a promising alternative to uranium as nuclear fuel with advantages such as higher abundance, lower production of long-lived transuranic elements, and potentially better proliferation resistance. However, thorium presents a potential pathway for proliferation where produced 233 Pa can be diverted for the clandestine production of safeguarded 233 U. To prevent this, the ability to detect and measure 233 Pa must be assessed. This paper reviews several nuclear material accountancy techniques to determine their suitability for detecting 233 Pa extracted from irradiated thorium fuel. Hybrid K-edge densitometry and passive gamma spectroscopy have been found to be the best options based on technology maturity, cost, accuracy, and acquisition time. Thorium can be used in various reactor designs such as pressurized water reactors (PWRs), Canada deuterium uranium (CANDU) reactors, and molten salt reactors (MSRs). Therefore, thorium-uranium oxide fueling was modeled for three representative reactors (PWR, CANDU, MSR), burning the fuel to 47 GWd/MTHM for PWR, 19 GWd/MTHM for CANDU, and at a steady power of 52.711 MW/MTHM for MSR. Within each model, the protactinium element in the used fuel was extracted and its isotopic content analyzed. Simulated results indicated that 233 Pa can be detected using passive gamma spectroscopy in each fuel type at all decay times (0–300 days) following separation.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Prediction of the structures and heats of formation of MO 2 , MO 3 , and M 2 O 5 for M = V, Nb, Ta, Pa

Structures for the mono-, di-, and tri-bridge isomers of M 2 O 5 as well as those for the MO 2 and MO 3 fragments for M = V, Nb, Ta, and Pa were optimized at the density functional theory (DFT) level. Single point CCSD(T) calculations extrapolated to the complete basis set (CBS) limit at the DFT geometries were used to predict the energetics. Here, the lowest energy dimer isomer was the di-bridge for M = V and Nb and the tri-bridge for M = Ta and Pa. The di-bridge isomers were predicted to be composed of MO 2 + and MO 3 - fragments, whereas the mono- and tri-bridge are two MO 2 + fragments linked by an O 2 - . The heats of formation of M 2 O 5 dimers, as well as MO 2 and MO 3 neutral and ionic species were predicted using the Feller–Peterson–Dixon (FPD) approach. The heats of formation of the MF 5 species were calculated to provide additional benchmarks. Dimerization energies to form the M 2 O 5 dimers are predicted to become more negative going down group 5 and range from -29 to -45 kcal mol -1 . The ionization energies (IEs) for VO 2 and TaO 2 are essentially the same at 8.75 eV whereas the IEs for NbO 2 and PaO 2 are 8.10 and 6.25 eV, respectively. The predicted adiabatic electron affinities (AEAs) range from 3.75 eV to 4.45 eV for the MO 3 species and vertical detachment energies from 4.21 to 4.59 eV for MO 3 - . The calculated M[double bond, length as m-dash]O bond dissociation energies increase from 143 kcal mol -1 for M = V to ~170 kcal mol -1 for M = Nb and Ta to ~200 kcal mol -1 for M = Pa. The M–O bond dissociation energies are all similar ranging from 97 to 107 kcal mol -1 . Natural bond analysis provided insights into the types of chemical bonds in terms of their ionic character. Pa 2 O 5 is predicted to behave like an actinyl species dominated by the interactions of approximately linear PaO 2 + groups.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Pennsylvania Department of Environmental Protection (PA DEP) 26r Detailed Produced Water Compositions (version 2.0)

A database of geochemical compositions of aqueous species in produced water reported to the PA Department of Environmental Protection (PA DEP). Samples were collected between late-2010 to late-2024. Data from publicly available PA DEP 26r reports were scraped from pdf files and cumulated into tabular spreadsheet format for >3,000 produced water streams from Marcellus Shale wells in Pennsylvania. In addition to providing the original values, the NETL NEWTS team has reformatted the dataset to allow sample streams to be easily copied into OLI Studio and Geochemist WorkBench (GWB) software for modeling the geochemistry and the recovery of critical minerals, such as lithium, from these produced water streams. ***This dataset is an updated version of the PA DEP 26r Detailed Produced Water Compositions (version 1.0) dataset, providing expanded spatial and temporal coverage.***

Aqueous Chemistry↗
DOE OSTI2022

Impact of fully coherent energy loss on heavy meson production in pA collisions

Hadron production in proton-nucleus (pA) collisions was previously shown to be suppressed by medium-induced fully coherent energy loss (FCEL). We show that the quenching of D and B mesons in pPb collisions at the LHC due solely to FCEL is, at least, on par with other nuclear effects such as gluon shadowing or saturation. This is consistent with previous findings for both quarkonium and light hadron production in pA collisions, emphasising that FCEL effects need to be included for a reliable understanding of hadron production measurements in pA collisions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Hydrolysis of Metal Dioxides Differentiates d-block from f-block Elements: Pa(V) as a 6d Transition Metal; Pr(V) as a 4f “Lanthanyl”

Gas-phase reactions of pentavalent metal dioxide cations M V O 2 + with water were studied experimentally for M = V, Nb, Ta, Pr, Pa, U, Pu, and Am. Addition of two H 2 O can occur by adsorption to yield hydrate (H 2 O) 2 M V O 2 + or by hydrolysis to yield hydroxide M V (OH) 4 + . Displacement of H 2 O by acetone indicates hydrates for Pr V , U V , Pu V , and Am V , whereas nondisplacement indicates hydroxides for Nb V , Ta V , and Pa V . Computed potential energy profiles agree with the experimental results and furthermore indicate that acetone unexpectedly induces dehydrolysis and displaces two H 2 O from (H 2 O)VO(OH) 2 + to yield (acetone) 2 VO 2 + . Structures and energies for several M V , as well as for Th IV and U VI , indicate that hydrolysis is governed by the involvement of valence f versus d orbitals in bonding: linear f-element dioxides are more resistant to hydrolysis than bent d-element dioxides. Accordingly, for early actinides, hydrolysis of Th IV is characteristic of a 6d-block transition metal; hydration of U V and U VI is characteristic of 5f actinyls; and Pa V is intermediate between 6d and 5f. The praseodymium oxide cation Pr V O 2 + is assigned as an actinyl-like lanthanyl with properties governed by 4f bonding.

36 MATERIALS SCIENCE↗
DOE OSTI2025

A Wind-driven Origin for the Firework Morphology of the Supernova Remnant Pa 30

Pa 30—the likely remnant of the Galactic Type Iax supernova of 1181 AD—displays an unusual, firework-like morphology, consisting of radial filaments extending from a common center, where a white dwarf (WD) currently drives a very fast wind (speed ≳10 4 km s −1 ). We propose the filaments arose from the Rayleigh–Taylor-unstable nature of the interface between the circumstellar medium (CSM) and the shocked wind launched by the natal WD; the filaments then elongated intact due to the Kelvin–Helmholtz-stable nature of the large initial density contrast between the wind and CSM, supplemented by the slowly declining wind density profile (relative to homologously expanding ejecta). To support this interpretation, we present two-dimensional hydrodynamical simulations and derive the filament properties, including their speed, density, and temperature, all of which are consistent with observations. We suggest the filaments elongate until the wind and CSM densities become comparable at the contact discontinuity, which occurs within 1–10 yr, and then truncate because the Rayleigh–Taylor instability (RTI) halts. The subsequent Kelvin–Helmholtz instability growth timescale across the current width of the filaments is longer than the age of Pa 30, so they remain intact. The filament-less central region in Pa 30 is therefore more likely a consequence of the finite timescale over which the RTI operates, rather than a wind termination shock. In general, firework-like filaments may form in other systems, provided there is a sufficiently large density contrast between the ejecta and its surroundings.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

High Time Resolution Modelled and Measured New Particle Formation Rates During the 2023 Pittsburgh, PA Campaign

Particle size distributions are used to calculate nucleation rates during new particle formation (NPF). However, the low time resolution and poor sensitivity of instruments deployed to observe particle size distributions can lead to inaccurate estimates of nucleation rates. We calculated nucleation rates in Pittsburgh, PA from particle size distributions measured with the new high time resolution Condensation Particle Counters For Atmospheric Rapid Measurements (CPC FARM) and from gas precursor concentrations measured with a chemical ionization mass spectrometer. The CPC FARM nucleation rates were calculated by examining the appearance rate of particles in the smallest size bin at 1.6 nm. The nucleation rate of 1.6 nm determined every second resulted in positive and negative rates, indicating the influence of inhomogeneous mixing and advection of precursor gases and clusters. These effects are not currently considered when estimating nucleation rates from measurements. The nucleation rates from the CPC FARM were compared to the nucleation rates determined from a transient acid‐base reaction model using measured sulfuric acid concentration, strong base concentrations, and CPC detection efficiencies. The transient form of the model allowed the advection of heterogeneously mixed precursors to influence the nucleation rate. Good agreement between particle and gas‐based nucleation rates is observed during sulfuric acid‐driven NPF events. This study demonstrates that high time resolution measurements of short‐lived and rapidly formed particles are needed to accurately capture nucleation rates, which are likely influenced by advection of nucleation precursors and clusters in heterogeneous environments such as urban areas.

Cheng, D. [Carnegie Mellon Univ., Pittsburgh, PA (↗
DOE OSTI2020

Fully coherent energy loss effects on light hadron production in pA collisions

We single out the role of fully coherent induced gluon radiation on light hadron production in pA collisions. The effect has the same general features as for quarkonium production, however with a richer color structure as the induced radiation depends on the global color charge of the partonic subprocess final state. Baseline predictions for light hadron nuclear suppression in pPb collisions at the LHC are provided, taking into account only the effect of fully coherent energy loss, which proves to be of the same order of magnitude as gluon shadowing or saturation. This underlines the need to include fully coherent energy loss in phenomenological studies of hadron production in pA collisions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

New measurements of gamma-ray energies and their absolute intensities from the decay of 231 Pa

Accurate nuclear data for the decay of 231 Pa is highly important for non-destructive analysis in the areas of radiochronometry and nuclear forensics. However, the evaluated nuclear data for this isotope is lacking; many previous measurements have large uncertainties and only two measurements are used to determine the absolute intensities. In this work, we present modern measurements of the major gamma-ray emissions from the decay of 231 Pa to 227 Ac including the energies and absolute intensities. For many of these measurements, the error envelopes have been significantly decreased compared to previous measurements, while remaining in good agreement. The absolute intensity of the 283 keV reference line was measured as 0.0163(2).

231Pa↗
DOE OSTI2021

Hydrolysis of Small Oxo/Hydroxo Molecules Containing High Oxidation State Actinides (Th, Pa, U, Np, Pu): A Computational Study

The energetics of hydrolysis reactions for high oxidation states of oxo/hydroxo monomeric actinide species (Th IV O 2 , Pa IV O 2 , U IV O 2 , Pa V O 2 (OH), U V O 2 (OH), U VI O 3 , Np VI O 3 , Np VII O 3 (OH), and Pu VII O 3 (OH)) were calculated at the CCSD(T) level. The first step is the formation of a Lewis acid/base adduct with H 2 O (hydration), followed by a proton transfer to form a dihydroxide molecule (hydrolysis); this process is repeated until all oxo groups are hydrolyzed. The physisorption (hydration) for each H 2 O addition was predicted to be exothermic, ca. -20 kcal/mol. The hydrolysis products are preferred energetically over the hydration products for the +IV and +V oxidation states. The compounds with An VI are a turning point in terms of favoring hydration over hydrolysis. For An VII O 3 (OH), hydration products are preferred, and only two waters can bind; the complete hydrolysis process is now endothermic, and the oxidation state for the An in An(OH) 7 is +VI with two OH groups each having one-half an electron. The natural bond order charges and the reaction energies provide insights into the nature of the hydrolysis/hydration processes. The actinide charges and bond ionicity generally decrease across the period. Here, the ionic character decreases as the oxidation state and coordination number increase so that covalency increases moving to the right in the actinide period.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Soil Water Potentials (1990-2018) from a calibrated ELM-FATES, and rooting depth analyses scripts, PA-BCI, Panama

This dataset has ELM-FATES simulation outputs and scripts that accompany and reproduce the manuscript, Chitra-Tarak et al. (2021) Hydraulically-vulnerable trees survive on deep-water access during droughts in a tropical forest. New Phytologist. https: //doi.org/10.1111/nph.17464”. This dataset is organized into four parts: (1) source code for the model, Energy Exascale Earth System Land Model-Functionally Assembled Advanced Terrestrial simulator (ELM-FATES) (2) R scripts associated with ELM-FATES simulations: to prepare files for parameter ensemble simulation runs, calibrate the model with observed hydrological fluxes observed at BCI, re-run the model with tuned parameters and obtain long-term soil matric potentials by depth (3) ELM-FATES hydrological simulation outputs at PA-BCI, Panama (1990-2018, daily), and (4) R scripts for inverse rooting depth modeling and post-processing: prepare datasets and inversely model tree rooting depths at BCI, test hypotheses about the relationship of rooting depths with plant hydraulic traits and drought-induced mortality, and reproduce the manuscript itself. n.b. 1. Data needed to run R scripts in (2) and (4) and thus to reproduce the manuscript are sourced from various public datasets. Refer to the data availability section of the accompanying manuscript. 2. This dataset version (prepared on May 12, 2021) matches the revised and published version of the accompanying manuscript (published May 16, 2021) replacing a previous version. In the publication, this dataset is cited as follows: Chitra-Tarak R, Xu C, Aguilar S, Anderson-Teixeira K, Chambers J, Detto M, Faybishenko B, Fisher R, Knox R, Koven C et al. 2020. Soil water potentials (1990–2018) from a calibrated ELM-FATES, and rooting depth analyses scripts, PA-BCI, Panama. 2.0. NGEE Tropics Data Collection. doi: 10.15486/ngt/1696806

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Leaf demography spectra, February 2017, PA-SLZ: Panama

This dataset contains leaf reflectance spectra of sunlit canopy leaves from trees at the San Lorenzo Protected Area (PA-SLZ), Panama. Spectra were measured with a full-spectrum (350 -2500 nm) spectroradiometer with a leaf clip attachment. Leaves previously documented in a demography survey were targeted, and each leaf spectrum is paired with species identification, relative leaf position on each branch and estimated leaf age in days. Leaves were measured from the following species: Apeiba membranacea, Carapa guianensis, Guatteria dumetorum, Miconia borealis, Tachigali versicolor, Terminalia amazonia, Tocoyena pittieri and Vochysia ferruginea Unprocessed spectral data are included as SVC *.sig files, and metadata, including sample details, are presented in *.xlsx files. Leaf reflectance spectra of sunlit canopy leaves from trees at the San Lorenzo Protected Area (PA-SLZ), Panama. Spectra were measured with a full-spectrum (350 -2500 nm) spectroradiometer with a leaf clip attachment. Leaves previously documented in a demography survey were targeted, and each leaf spectrum is paired with species identification, relative leaf position on each branch and estimated leaf age in days. Leaves were measured from the following species: Apeiba membranacea, Carapa guianensis, Guatteria dumetorum, Miconia borealis, Tachigali versicolor, Terminalia amazonia, Tocoyena pittieri and Vochysia ferruginea Unprocessed spectral data are included as SVC *.sig files, and metadata, including sample details, are presented in *.xlsx files.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Leaf-to-canopy spectral reflectance, February 2018, PA-SLZ: Panama

Canopy reflectance spectra of 37 trees were measured at the Smithsonian Tropical Research Institute (STRI) San Lorenzo Protected Area site (PA-SLZ), utilising the canopy access crane to access fully sunlit leaves. Data were recorded in the middle of the day, with 20–50 measurements for each tree. The canopy structure for each crown was captured using a digital camera. Leaf-level reflectance and leaf demographic composition (age class) was recorded in detail for a > 0.5 meter branch sampled from each canopy tree (corresponding to the position where canopy spectra were measured). This dataset includes processed canopy and leaf-level spectral measurements (*.xlsx), raw spectral data (Spectral Evolution PSR+, *.raw, *.sed), sample details (*.xlsx) and *.pdf summaries containing low resolution photographs of the measured canopies. Full resolution images are available in the related dataset, "Leaf-to-canopy spectral reflectance photographs, February 2018, PA-SLZ: Panama".

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

AmeriFlux PA-Bar Barro Colorado Island

This is the AmeriFlux version of the carbon flux data for the site PA-Bar Barro Colorado Island. Site Description - Barro Colorado Island supports a humid tropical forest with high biodiversity, with 314 tree species in 50 ha. The climate has a strong four-month dry season from late December to late April. Several deciduous species drop their leaves during this period. Lianas are very abundant accounting for 20% of dry leaf biomass. This is the original location of the BCI flux tower, now replaced by PA-Bas

Wright, Joseph [Smithsonian Tropical Research Inst↗