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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 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Impact of Fission Products Impurity on the Plutonium Content of Metal- and Oxide- Fuels in Sodium Cooled Fast Reactors

This short report presents the neutronic analysis to evaluate the impact of fission product impurity on the Pu content of Sodium-cooled Fast Reactor (SFR) metal- and oxide- fuel fabrication. The similar work has been previously done for PWR MOX fuel. The analysis will be performed based on the assumption that the separation of the fission products (FP) during the reprocessing of UOX spent nuclear fuel assemblies is not perfect and that, consequently, a certain amount of FP goes into the Pu stream used to fabricate SFR fuels. Only non-gaseous FPs have been considered (see the list of 176 isotopes considered in the calculations in Appendix 1 of Reference 1). Throughout of this report, we define the mixture of Pu and FPs as Pu FP . The main objective of this analysis is to quantify the increase of the Pu content of SFR fuels necessary to maintain the same average burnup at discharge independently of the amount of FP in the Pu stream, i.e. independently of the Pu FP composition. The FP losses are considered element-independent, i.e., for example, 1% of FP losses mean that 1% of all non-gaseous FP leak into the Pu stream.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

A Calibration to Predict the Concentrations of Impurities in Plutonium Oxide by Prompt Gamma Analysis Revision 2

This report documents the new PG calibration regression equation. These calibration equations incorporate new data that have become available since revision 1 of “A Calibration to Predict the Concentrations of Impurities in Plutonium Oxide by Prompt Gamma Analysis” was issued [3] The calibration equations are based on a weighted least squares (WLS) approach for the regression. The WLS method gives each data point its proper amount of influence over the parameter estimates. This gives two big advantages, more precise parameter estimates and better and more defensible estimates of uncertainties. The WLS approach makes sense both statistically and experimentally because the variances increase with concentration, and there are physical reasons that the higher measurements are less reliable and should be less influential. The new magnesium calibration includes a correction for sodium and separate calibration equation for items with and without chlorine. These additional calibration equations allow for better predictions and smaller uncertainties for sodium in materials with and without chlorine. Chlorine and sodium have separate equations for RICH materials. Again, these equations give better predictions and smaller uncertainties chlorine and sodium for RICH materials.

Instrumentation Related to Nuclear Science & Techn↗
DOE OSTI2017

Li-FSI Impurity Impact Study: Final CRADA Report

There is growing interest in lithium bis(fluorosulfonyl)imide (LiFSI ) as an alternative to LiPF6 and as an additive to electrolytes used in lithium-ion cells. LiFSI has attracted attention because it is reported to have higher ionic conductivity, better high temperature stability, and enhanced stability toward hydrolysis, Also, LiFSI additive to electrolytes can bring benefits of improved storage properties and reduced gas evolution in the cells. Different levels of different electrochemically active impurities could affect the performance of LiFSI as an electrolyte salt for Li-ion batteries, generating inconsistent and conflicting interpretations of the experimental data.

25 ENERGY STORAGE↗
DOE OSTI2019

Mitigation of Chromium Impurity Effects and Degradation in Solid Oxide Fuel Cells: The Roles of Reactive Transport and Thermodynamics

The principal objectives of this project were to understand the combined role of transport and thermodynamics in chromium poisoning of solid oxide fuel cell (SOFC) cathodes. Specifically, the differences in the chromium poisoning phenomena in predominantly electronic conducting cathodes such as strontium-doped lanthanum manganite (LSM) and mixed conducting cathodes such as strontium-doped lanthanum ferrite (LSF) and lanthanum nickelate (LNO) have been experimentally elucidated. The voltage-current density curves obtained from single cells featuring these cathode materials in the presence of chromium impurity have been analyzed using a suitable electrochemical model. The results clearly show the higher chromium tolerance of LSF and LNO cathodes compared to LSM cathodes. Further, dense protective coatings of copper-manganese spinel oxide applied via electrophoretic deposition (EPD) conformally on ferritic stainless steel current collectors that simulate the interconnection in SOFC stacks have been applied to SOFCs featuring LSM cathodes. Operation over a period of ten days of SOFCs featuring bare and spinel–coated ferritic stainless steel mesh current collectors show that the coatings are highly effectiveto protect against chromium poisoning.

03 NATURAL GAS↗
DOE OSTI2019

A First-Principles Study of the Vacancy-Mediated Silver Impurity Diffusion in fcc Nickel

In this report, ab initio techniques (Density Functional Theory, DFT) are used to calculate the vacancy-mediated self-diffusion coefficient and impurity diffusion coefficient of silver (Ag) in pure fcc nickel (Ni). Prediction of diffusion coefficients is one of the most stringent tests of the ability of DFT calculations, because of the complex interplay of lattice constant, vacancy formation enthalpy, solute-vacancy binding enthalpy, and vibrational frequencies. The Ag diffusion and Ni self-diffusion coefficients calculated in the present work compare very favorably to previous experimental self-diffusion and Ag diffusion data. Extension of the methodology to nickel alloys is envisioned in future work.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Study of Poly(ether ketone ketone) (PEKK): Outgassing Characteristics and Likely Residual Synthesis Impurities

In May-June, 2020, a study was conducted to characterize the outgassing properties of a series PEKK (Poly(ether ketone ketone)) samples using cryo-GC/MS headspace analysis. Three sets of samples were interrogated: sample group 1 consisted of 2 additively manufactured PEKK samples (PEKK "ole and "New") prepared by KCNSC from powder material from Solvay Specialty Polymers USA, LLC. Sample groups 2 and 3 consist of 5 PEKK powder types (used as feedstock for additive manufacturing processes) and 4 additively-manufactured PEKK material lots, respectively. Contrary to expectations, all samples of PEKK material were observed to outgas sulfur-containing compounds. Other analyses (EDS/EMA, GC-TOF/MS of PEKK sample extractions) confirmed the presence of sulfur in the PEKK bulk material. Specifically, Diphenyl sulfone (used as a reagent or high-temperature solvent in the synthesis of Polyaryletherketone or PAEK polymers) was observed in three of the powders and in both the PEKK "Old" and "New" samples, suggesting that the source of the sulfur can be traced to impurities in the material left over from the synthesis process.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Irradiation of Sintered Mo Disks with Presence of Organic Impurities in He Gas Flow

Argonne National Laboratory (Argonne) is assisting NorthStar Medical Technologies in the development of a domestic supply of 99 Mo. Specifically, the present study focuses on the production of 99 Mo-feed solution used by the RadioGenix™ 99m Tc generator. During the target-irradiation phase of production, impurities can potentially be introduced into the feed, and can lead to disturbance of ligand- 99m Tc complexation chemistry and contamination of the final radiopharmaceutical that directly interacts with the patient. To address this issue, Argonne performed irradiations and chemical processing to identify whether the potential contamination of He flow with hydrocarbon oil during irradiation affects the radiochemical purity of the final K 2 MoO 4 (K 2 TcO 4 ) in 5M KOH solution. To mimic the conditions of real irradiation at NorthStar, Argonne used its electron linear accelerator and Van de Graaff facilities, heated the target and oil source to >800°C, and controlled oxygen in the presence of He during irradiation. Following irradiation, scanning electron microscopy (SEM) and carbon analysis (CA) were used to detect carbon contamination on the solid targets. The radiochemical purity of the dissolved targets was studied via thin-layer paper chromatography (TLC). As a result of these experiments, small regions of the surface of some irradiated disks were found to be high in carbon, but the total carbon content was still negligible in comparison to the reference sample, which had experienced no irradiation or contact with oil. The summarized results from the SEM, CA, and TLC tests lead to the conclusion that even an excess of oil and heating during irradiation do not affect the radiochemical purity of the final product.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2023

Impurity Monitoring During Multiple Recycles of Mo Targets for Accelerator-Produced Mo-99

Accelerator-based methods have been developed to produce kilocurie quantities of low specific-activity 99 Mo from Mo targets. The irradiation of enriched 100 Mo, in place of nat Mo, greatly reduces the activity of side-reaction products formed from other Mo isotopes, which have a fairly wide distribution of natural isotopic abundances: 92 Mo (14.8%), 94 Mo (9.3%), 95 Mo (15.9%), 96 Mo (16.7%), 97 Mo (9.5%), and 98 Mo (21.4%). The side-reaction impurities of chief concern are 91m Nb and 88 Zr/ 88 Y (from 92 Mo), 92m Nb (from 94 Mo), and 95 Nb, 96 Nb, and 97 Nb (from 98 Mo). The new production technologies also require new chemical processing and purification schemes that emphasize low-waste recycling of the expensive, enriched Mo material.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

A Multifidelity and Multimodal Machine Learning Approach for Extracting Bonding Environments of Impurities and Dopants from X-ray Spectroscopies

Extended X-ray absorption fine structure (EXAFS) spectroscopy is crucial for determining the coordination environment of impurities and dopants; however, it requires difficult measurements. X-ray absorption near edge structure (XANES) spectroscopy and X-ray emission spectroscopy (XES) can be obtained easily but cannot be converted to determine structures. In this work we develop tools to map measured XANES to the EXAFS signal through machine learning, thereby facilitating the use of EXAFS structural-determination analyses on XANES data. Through the use of Deep Operator Networks (DeepONets), we are able to accurately predict the EXAFS spectrum between 6 and 14 Å -1 from the first 6 Å -1 (~100 eV) of the absorption spectrum of Cu 2+ substitutional defects in the Fe 3+ mineral hematite (a-Fe 2 O 3 ). This surprising finding implies that theoretical analyses of X-ray absorption spectra could be implemented that extract the same conclusions as high-quality EXAFS studies from spectra collected over a much smaller range of photon energies. To encourage similar efforts, the simulated x-ray spectra, machine learning, and fitting code is made publicly available.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

3D simulation of H-mode plasmas with localized divertor impurity injection on Alcator C-Mod using the edge transport code EMC3-EIRENE

Experiments in Alcator C-Mod to assess the level of toroidal asymmetry in divertor conditions resulting from poloidally and toroidally localized extrinsic impurity gas seeding show a weak toroidal peaking (~1.1) in divertor electron temperatures for high-power Enhanced D-alpha H-mode plasmas. This is in contrast to similar experiments in Ohmically heated L-mode plasmas, which showed a clear toroidal modulation in the divertor electron temperature. Modeling of these experiments using the 3D edge transport code EMC3-EIRENE [Y. Feng, et al., J. Nucl. Mater., 241 (1997) 930] qualitatively reproduces these trends, and indicates that the different response in the simulations is due to the ionization location of the injected nitrogen. Low electron temperatures in the private flux region (PFR) in L-mode

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗