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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Interpretation of aircraft multispectral scanner images for mapping of alteration with uranium mineralization, Copper Mountain, Wyoming

NS-001 multispectral scanner data (0.45-2.35 micron) combined as principal components were utilized to map distributions of surface oxidation/weathering in Precambrian granitic rocks at Copper Mountain, Wyoming. Intense oxidation is found over granitic outcrops in partly exhumed pediments along the southern margin of the Owl Creek uplift, and along paleodrainages higher in the range. Supergene(?) uranium mineralization in the granites is localized beneath remnant Tertiary sediments covering portions of the pediments. The patterns of mineralization and oxidation are in agreement, but the genetic connections between the two remain in doubt.

Conel, J. E.↗
NASA NTRS1987

Quadrupolar Kondo effect in uranium heavy-electron materials?

The possibility of an electric quadrupole Kondo effect for a non-Kramers doublet on a uranium (U) ion is a cubic metallic host is demonstrated by model calculations showing a Kondo upturn in the resistivity, universal quenching of the quadrupolar moment, and a heavy-electron anomaly in the electronic specific heat. With inclusion of excited crystal-field levels, some of the unusual magnetic-response data in the heavy-electron superconductor UBe13 may be understood. Structural phase transitions at unprecedented low temperatures may occur in U-based heavy-electron materials.

Cox, D. L.↗
NASA NTRS1987

Models of Uranium continuum radio emission

Uranium continuum radio emission detected by the Voyager 2 Planetary Radio Astronomy experiment during the January 1986 encounter is considered. The continuum emissions comprised four components (equatorial emissions, anomaly emissions, strong nightside emissions, and weak nightside emissions) associated with different sources. The equatorial emissions appeared most prominently during the days before closest approach and extended from 40 kHz or below to about 120 kHz. The anomaly emissions were seen about 12 hours before closest approach and extended to about 250 kHz. The agreement found between Miranda's phase and strong radio emission at 20.4 kHz, just after closest approach, suggests intense dynamic activity on the Miranda L shell.

Romig, Joseph H.↗
NASA NTRS1989

Uranium-series dated authigenic carbonates and Acheulian sites in southern Egypt

Field investigations of aggraded paleovalleys, which were identified in southern Egypt using SIR, are discussed. Acheulian artifacts were found in authigenic carbonate deposites along the edges of the paleovalleys. Uranium series dating of 25 carbonate samples shows that widespread carbonate deposition in the area occurred about 45, 141, and 212 thousand years ago. Analysis of the carbonate suggests that the deposition may be related to late Pleistocene humid climates that facilitated human settlement in the region.

Szabo, B. J.↗
NASA NTRS1993

Thermophysical properties of gas phase uranium tetrafluoride

Thermophysical data of gaseous uranium tetrafluoride (UF4) are theoretically obtained by taking into account dissociation of molecules at high temperatures (2000-6000 K). Determined quantities include specific heat, optical opacity, diffusion coefficient, viscosity, and thermal conductivity. A computer program is developed for the calculation.

Watanabe, Yoichi↗
NASA NTRS1961

Consistent Pl Analysis of Aqueous Uranium-235 Critical Assemblies

The lethargy-dependent equations of the consistent Pl approximation to the Boltzmann transport equation for slowing down neutrons have been used as the basis of an IBM 704 computer program. Some of the effects included are (1) linearly anisotropic center of mass elastic scattering, (2) heavy element inelastic scattering based on the evaporation model of the nucleus, and (3) optional variation of the buckling with lethargy. The microscopic cross-section data developed for this program covered 473 lethargy points from lethargy u = 0 (10 Mev) to u = 19.8 (0.025 ev). The value of the fission neutron age in water calculated here is 26.5 square centimeters; this value is to be compared with the recent experimental value given as 27.86 square centimeters. The Fourier transform of the slowing-down kernel for water to indium resonance energy calculated here compared well with the Fourier transform of the kernel for water as measured by Hill, Roberts, and Fitch. This method of calculation has been applied to uranyl fluoride - water solution critical assemblies. Theoretical results established for both unreflected and fully reflected critical assemblies have been compared with available experimental data. The theoretical buckling curve derived as a function of the hydrogen to uranium-235 atom concentration for an energy-independent extrapolation distance was successful in predicting the critical heights of various unreflected cylindrical assemblies. The critical dimensions of fully water-reflected cylindrical assemblies were reasonably well predicted using the theoretical buckling curve and reflector savings for equivalent spherical assemblies.

Fieno, Daniel↗
NASA NTRS2009

Using Volcanic Ash to Remove Dissolved Uranium and Lead

Experiments have shown that significant fractions of uranium, lead, and possibly other toxic and/or radioactive substances can be removed from an aqueous solution by simply exposing the solution, at ambient temperature, to a treatment medium that includes weathered volcanic ash from Pu'u Nene, which is a cinder cone on the Island of Hawaii. Heretofore, this specific volcanic ash has been used for an entirely different purpose: simulating the spectral properties of Martian soil. The treatment medium can consist of the volcanic ash alone or in combination with chitosan, which is a natural polymer that can be produced from seafood waste or easily extracted from fungi, some bacteria, and some algae. The medium is harmless to plants and animals and, because of the abundance and natural origin of its ingredient( s), is inexpensive. The medium can be used in a variety of ways and settings: it can be incorporated into water-filtration systems; placed in contact or mixed with water-containing solids (e.g., soils and sludges); immersed in bodies of water (e.g., reservoirs, lakes, rivers, or wells); or placed in and around nuclear power plants, mines, and farm fields.

McKay, David S.↗
NASA NTRSDate not supplied

Hot Hydrogen Testing of Uranium Nitride Cermet for Nuclear Thermal Propulsion

This study investigated the thermochemical stability and performance characteristics of uranium mononitride tungsten molybdenum cermet (UN-Mo30W) as a potential fuel material for Nuclear Thermal Propulsion (NTP) engines. Twelve monolithic cylinders were subjected to conditions simulating an active NTP engine. The tests demonstrated thermal variability within the test article and highlighted the dissociation of UN into U and N2 at elevated temperatures, affecting the microstructure and causing bonding between cermet wafers and cooling tubes. Findings indicate that while UN-Mo30W cermet exhibits some desirable properties for NTP applications, its suitability is limited by high-temperature thermochemical instability.

nuclear fuels↗
DOE OSTI2024

The Electron Thermal Conductivity of Pu and Zr Substituted Gamma-Uranium

Uranium alloys are attractive recycled nuclear fuels because of their high thermal conductivity (k) and fissile density; however, the effects of alloying elements on k remain unclear. Here, the electron thermal conductivity (k_e) of U-Pu-Zr compositions are calculated using density functional theory. The electronic structure is evaluated to understand the effects of plutonium (Pu) and zirconium (Zr) substitution on the k_e of ?-U. Alloys of up to 37.5 at. % Pu and 37.5 at. % Zr are examined. Two methods are applied to calculate k_e; we find that the accuracy of each method depends on the electronic and mass similarities between the solute and solvent atoms. Specifically, when the solute atom is similar in electronic structure and mass, the method that applies the electron relaxation time of ?-U is best, while if the elements are dissimilar, a mixed method that mixes several parameters associated with k_e from each element in the alloy is best. The introduction of all alloying elements decreases k_e; however, in binary compounds, Pu and Zr have different effects. Pu generally flattens the electronic bands but compensates for this deleterious effect by increasing electron density near the Fermi level. Zr flattens the electronic bands more severely without adding electron density near the Fermi level. Therefore, Zr decreases the k_e more than Pu in binary compounds. In ternary compounds, the difference between Pu and Zr is minimal due to the phononic change from the large mass change of Zr substitution, even at 12.5 at. %. Thus, we predict that higher loadings of Pu, and potentially other actinides, can be added to U-Pu-Zr compositions for faster recycling of spent fuel with without sacrificing k. We also note that these k_e calculation methods can be applied to non-fuel alloys that require k_e predictions, such as cladding, heat exchanger, and structural materials.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Hydrochlorination of Uranium Dioxide in a Molten Salt Mixture- Phase 2: Sparged Benchtop Reaction Vessel Experiment

In 2023, Metatomic® Inc., a South Carolina based company, was awarded a Gateway for Advanced Innovation in Nuclear (GAIN) research voucher for a proposed series of experiments aimed at demonstrating the viability of a spent nuclear fuel (SNF) recycling process patented by Metatomic Inc. For the GAIN voucher, Metatomic Inc. selected Savannah River National Laboratory (SRNL) as a partner in executing the proposed proof-of-concept experiments. This report outlines the proof-of-concept experiments performed by SRNL for Metatomic Inc. during Phase 2 (of 2) experimentation. Though Phase 1 provided evidence of successful hydrochlorination, Phase 2 highlighted the nuances and challenges associated with scaling the reaction. The target UCl 4 species generated by the hydrochlorination of UO 2 generates water, which consumes UCl 4 . Compared to the single datapoint obtained at the end of the Phase 1 experiments, data collected at multiple timepoints during Phase 2 experiments indicated a presumed maximum percent conversion of 23% for this system that is likely influenced by water generation. Engineering improvements might be able to increase the percent conversion, but not likely to the degree needed for successful implementation of the technology. Moisture also presents an issue for the Hastelloy C276 reaction vessel. Eventually, corrosion will compromise the integrity of the reaction vessel, and the corrosion products could potentially affect the hydrochlorination chemistry. The presence of corrosion products, which were not produced in the Phase 1 alumina crucible, can and have created challenges when analyzing samples.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Recovery of stable isotope taggants along a wet production pathway of uranium dioxide

Stable isotope taggants added to nuclear materials could be utilized as diagnostic nuclear forensics signatures; however, intentionally adding taggants is a relatively new and untested concept with respect to the nuclear fuel cycle. Here, in this study, we added trace amounts of stable Mo and W isotope taggants to starting materials used to synthesize UO 2 along a wet synthesis pathway. Successful incorporation and recovery of the Mo and W taggants was achieved in the UO 2 product and all its precursors. This study demonstrates the efficacy of stable isotope tagging along a wet UO 2 production pathway.

Nuclear forensics↗
DOE OSTI2025

Accelerated and heterogeneous corrosion of Cr-doped uranium nitride fuel pellets

The steam oxidation of Cr-doped UN fuel pellets is analyzed during sequential isothermal holds up to 720 °C. In situ neutron diffraction results show how Cr is accommodated in a secondary U 2 CrN 3 phase, leading to the formation of a duplex UN/U 2 CrN 3 microstructure. Under corrosion, the oxidation of the two phases begins at 400 °C for UN and 430 °C for U 2 CrN 3 , respectively. Because the UN phase is preferentially oxidized in the presence of U 2 CrN 3 , addition of Cr in UN based nuclear fuel is found to accelerate the corrosion rate. At 430 °C the oxidation of UN in the UN/U 2 CrN 3 microstructure is ~ 5 times faster than pure UN, increasing to ~19 times faster at 460 °C. The oxidation of U 2 CrN 3 produces UO 2 via the formation of two transient intermediate phases. In situ neutron diffraction enables oxidation processes of UN and U 2 CrN 3 components to be followed separately within the two-phase system.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Homoleptic 1,2-benzenedithiolate complexes of thorium and uranium

Reaction of 4 equiv. of [Li(TMEDA)] 2 [1,2-S 2 C 6 H 4 ] with [ThCl 4 (DME) 2 ] or [UCl 4 (THF) 3 ] in THF results in formation of [Li(THF) 2 ] 4 [An(1,2-S 2 C 6 H 4 ) 4 ] (An = Th, 1; An = U, 2), whereas reaction of 4 equiv. of [Li(TMEDA)] 2 [1,2-S 2 C 6 H 4 ] with UCl 4 in Et 2 O results in formation of [Li(TMEDA)] 4 [U(1,2-S 2 C 6 H 4 ) 4 ] (3). Complexes 1–3 represent the first reported benzenedithiolate complexes of the actinides. Here, they were characterized by NMR spectroscopy and X-ray crystallography. In the solid state, complexes 1–3 exhibit triangular dodecahedral geometries about their actinide centers. Additionally, their Li + cations are bound by two sulfur atoms of adjacent [1,2-S 2 C 6 H 4 ] 2− ligands, in addition to two solvent donor atoms. In solution, complexes 2 and 3 exhibit spectral data consistent with S 4 symmetry (and non-exchanging Li + sites), whereas complex 1 exhibits spectral properties consistent with labile Li + cations.

X-ray↗
DOE OSTI2025

Diffusion and phase formation in the γ-uranium-technetium system

Phase formation in the U-Tc binary system at 800 °C was investigated using a diffusion couple experiment. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) identified four novel potential intermetallic phases - U 7 Tc 3 , U 13 Tc 12 , U 3 Tc 5 , and UTc 4 . Diffusion coefficients were calculated for the intermetallic phases using the Boltzmann-Matano method and were respectively found to be – 120, 38.2, 15.6, and 1.51 × 10 −18 m 2 /s. Tc also exhibits a solid-solution phase with high penetration into the U with a diffusion coefficient of ∼ 10 −14 m 2 /s. Furthermore, these findings expand the number of known U-Tc phases and provide the first diffusion coefficients for the U-Tc system, and contribute valuable data to the broader field of actinide metallurgy.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗