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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on TcXeO4F5 by Materials Project

Xe(OF)2TcO2F3 crystallizes in the orthorhombic Cmc2_1 space group. The structure is one-dimensional and consists of four Xe(OF)2 clusters and two TcO2F3 ribbons oriented in the (0, 0, 1) direction. In each Xe(OF)2 cluster, Xe is bonded in a see-saw-like geometry to two equivalent O and two F atoms. Both Xe–O bond lengths are 1.86 Å. There are one shorter (2.05 Å) and one longer (2.10 Å) Xe–F bond lengths. O is bonded in a single-bond geometry to one Xe atom. There are two inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Xe atom. In the second F site, F is bonded in a single-bond geometry to one Xe atom. In each TcO2F3 ribbon, Tc is bonded to two O and four F atoms to form distorted corner-sharing TcO2F4 octahedra. The corner-sharing octahedral tilt angles are 23°. Both Tc–O bond lengths are 1.68 Å. There are a spread of Tc–F bond distances ranging from 1.88–2.14 Å. There are two inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Tc atom. In the second O site, O is bonded in a single-bond geometry to one Tc atom. There are two inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Tc atom. In the second F site, F is bonded in a bent 150 degrees geometry to two equivalent Tc atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1996

Electron Impact Excitation of Autoionizing Levels of Kr and Xe Between the (sup 2)P(sub 3/2) and (sup 2)P(sub 1/2) Ionic Limits

We have observed electrons ejected from autoionizing levels which lie between the (sup 2)P(sub 3/2) and (sup 2)P(sub 1/2) ionic limits for Kr and Xe. Kinetic energy spectra of the ejected electrons were obtained following electron impact excitation of the target gases by using time-of-flight spectroscopy in a crossed beam experiment. Spectral features which correspond to electrons ejected from both odd and even parity autoionizing levels have been identified.

autoionizing ejected electrons↗
DOE OSTI2020

Cluster dynamics simulation of xenon diffusion during irradiation in UO 2

Diffusion of fission gas in UO 2 nuclear fuel impacts several important performance metrics, such as fission gas release, swelling, and thermal conductivity. Current empirical models of fission gas release have significant uncertainty, some of which derives from the bulk diffusion rate and its dependence on, for example, fuel chemistry and irradiation. In this work, we have applied the previously-developed Free Energy Cluster Dynamics (FECD) methodology in the code Centipede to calculate xenon cluster concentrations in UO 2 under intrinsic (high temperature) and irradiation-enhanced (intermediate temperature) conditions in order to develop a model of the xenon diffusion coefficient based on the atomic scale mechanisms responsible for transport. While the diffusion mechanism for xenon in UO 2 is adequately described by the Xe + U 2 O vacancy cluster for intrinsic conditions, a similar process is not capable of capturing measured in-pile fission gas diffusivity at intermediate temperatures. Therefore, a different diffusion mechanism must dominate under this regime. Using calculated atomistic data, we have shown that irradiation-enhanced diffusion at intermediate temperatures occurs via the larger Xe + U 4 O y vacancy clusters, which have lower migration barriers and increase in concentration by several orders of magnitude compared to intrinsic conditions. This mechanism is enabled by the increased uranium vacancy concentration under irradiation due to Frenkel pair production. In addition, the fast migration of uranium interstitials with two attached oxygen interstitials lowers the total uranium interstitial concentration through reactions with sinks. This allows the extended defects, such as Xe + U 4 O y vacancy clusters, to maintain high concentrations by limiting annihilation with attached vacancies. Furthermore, predictions using the Xe + U 4 O y diffusion mechanism are in good agreement with experiment, albeit with some differences in the Arrhenius slope, which we believe may be related to either experimental or model parameter uncertainty. Lastly, an analytical expression suitable for application in fuel performance simulations was derived to capture the predictions of the Centipede simulations.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Materials Data on Sb3S2XeN(O2F9)2 by Materials Project

XeSb3NS2(O2F9)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four XeSb3NS2(O2F9)2 clusters. Xe is bonded in a linear geometry to one N and one F atom. The Xe–N bond length is 2.13 Å. The Xe–F bond length is 2.44 Å. There are three inequivalent Sb sites. In the first Sb site, Sb is bonded to six F atoms to form corner-sharing SbF6 octahedra. The corner-sharing octahedral tilt angles are 29°. There are a spread of Sb–F bond distances ranging from 1.88–2.10 Å. In the second Sb site, Sb is bonded to six F atoms to form corner-sharing SbF6 octahedra. The corner-sharing octahedral tilt angles are 29°. There are a spread of Sb–F bond distances ranging from 1.88–2.15 Å. In the third Sb site, Sb is bonded to six F atoms to form corner-sharing SbF6 octahedra. The corner-sharing octahedral tilt angles are 29°. There are a spread of Sb–F bond distances ranging from 1.88–2.04 Å. N is bonded in a trigonal planar geometry to one Xe and two S atoms. There is one shorter (1.69 Å) and one longer (1.73 Å) N–S bond length. There are two inequivalent S sites. In the first S site, S is bonded to one N, two O, and one F atom to form distorted corner-sharing SNO2F tetrahedra. Both S–O bond lengths are 1.42 Å. The S–F bond length is 1.58 Å. In the second S site, S is bonded to one N, two O, and one F atom to form corner-sharing SNO2F tetrahedra. There is one shorter (1.42 Å) and one longer (1.43 Å) S–O bond length. The S–F bond length is 1.57 Å. There are four inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one S atom. In the second O site, O is bonded in a single-bond geometry to one S atom. In the third O site, O is bonded in a single-bond geometry to one S atom. In the fourth O site, O is bonded in a single-bond geometry to one S atom. There are eighteen inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Sb atom. In the second F site, F is bonded in a single-bond geometry to one Sb atom. In the third F site, F is bonded in a single-bond geometry to one Sb atom. In the fourth F site, F is bonded in a single-bond geometry to one Sb atom. In the fifth F site, F is bonded in a single-bond geometry to one Sb atom. In the sixth F site, F is bonded in a single-bond geometry to one Sb atom. In the seventh F site, F is bonded in a single-bond geometry to one Sb atom. In the eighth F site, F is bonded in a bent 150 degrees geometry to two Sb atoms. In the ninth F site, F is bonded in a bent 150 degrees geometry to two Sb atoms. In the tenth F site, F is bonded in a single-bond geometry to one Sb atom. In the eleventh F site, F is bonded in a single-bond geometry to one Sb atom. In the twelfth F site, F is bonded in a single-bond geometry to one S atom. In the thirteenth F site, F is bonded in a single-bond geometry to one S atom. In the fourteenth F site, F is bonded in a distorted linear geometry to one Xe and one Sb atom. In the fifteenth F site, F is bonded in a single-bond geometry to one Sb atom. In the sixteenth F site, F is bonded in a single-bond geometry to one Sb atom. In the seventeenth F site, F is bonded in a single-bond geometry to one Sb atom. In the eighteenth F site, F is bonded in a single-bond geometry to one Sb atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on S2Xe(O3F)2 by Materials Project

XeS2(O3F)2 is High Pressure (4-7GPa) Tellurium structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four XeS2(O3F)2 clusters. Xe is bonded in a linear geometry to two O atoms. There are one shorter (2.25 Å) and one longer (2.26 Å) Xe–O bond lengths. There are two inequivalent S sites. In the first S site, S is bonded in a tetrahedral geometry to three O and one F atom. There is two shorter (1.43 Å) and one longer (1.55 Å) S–O bond length. The S–F bond length is 1.60 Å. In the second S site, S is bonded in a tetrahedral geometry to three O and one F atom. There is two shorter (1.43 Å) and one longer (1.54 Å) S–O bond length. The S–F bond length is 1.60 Å. There are six inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to one Xe and one S atom. In the second O site, O is bonded in a bent 120 degrees geometry to one Xe and one S atom. In the third O site, O is bonded in a single-bond geometry to one S atom. In the fourth O site, O is bonded in a single-bond geometry to one S atom. In the fifth O site, O is bonded in a single-bond geometry to one S atom. In the sixth O site, O is bonded in a single-bond geometry to one S atom. There are two inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one S atom. In the second F site, F is bonded in a single-bond geometry to one S atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

The predicted shapes of voids and Xe bubbles in UO 2

Morphology is a fundamental attribute when investigating voids and bubbles in UO 2 . Here we use molecular dynamics and Monte Carlo simulations to predict the lowest energy shapes for voids and bubbles in UO 2 . The energies of the {100}, {110} and {111} surfaces have been calculated and used to predict the equilibrium void shape from Wulff construction. This equilibrium shape is compared to low energy faceted voids exhibiting different relative proportions of each family of terminating surfaces. It is found that the equilibrium Wulff shape does not represent the lowest energy morphology for nm void sizes at temperatures between 300 K and 1200 K. Furthermore, the lowest energy faceted voids are slightly more energetically favourable than spherical voids, and as Xe is added, and bubble pressure increases, the faceted morphology becomes even more favourable than the spherical shape.

36 MATERIALS SCIENCE↗
NASA NTRS1982

Sorption of noble gases by solids, with reference to meteorites. I - Magnetite and carbon

The trapping of meteoritic noble gases by solids is simulated through the synthesis of 18 Fe3O4 samples at 350-720 K in a noble gas atmosphere, by means of the reactions: (1) 3Fe + 4H2O yields Fe3O4 + 4H2, using Ne, Ar, Kr and Xe; and (2) 3Fe + 4CO yields Fe3O4 + 4C + carbides, using Xe. Etching experiments suggest an analogy with 'Phase Q' in meteorites. Adsorbed atmospheric gases are present in all samples, and dominate whenever the noble gas partial pressure in the atmosphere is greater than that in the synthesis. While many of the results of Lancet and Anders (1973) appear to have been dominated by such an atmospheric component, others are suspect. When the doubtful samples of Lancet and Anders are corrected or eliminated, the fractionation pattern no longer peaks at Ar, but rather, as in the present sample, rises monotonically from Ne to Xe. No evidence is found for the earlier study's claim of a strong temperature dependence.

Yang, J.↗
NASA NTRS1980

Computational study of alkali-metal-noble gas collisions in the presence of nonresonant lasers - Na + Xe + h/2/pi/omega sub 1 + h/2/pi/omega sub 2 system

The collision of Na with Xe in the presence of both the rhodamine-110 dye laser and the Nd-glass laser is investigated within a quantum-mechanical close-coupled formalism, utilizing ab initio potential curves and transition dipole matrix elements. Both one- and two-photon processes are investigated; the Na + Xe system is not asymptotically resonant with the radiation fields, so that these processes can only occur in the molecular collision region. The one-photon processes are found to have measurable cross sections at relatively low intensities; even the two-photon process has a significant section for field intensities as low as 10 MW/sq cm.

Devries, P. L.↗
DOE OSTI2020

Environmental remediation with functional aerogels and xerogels

Several different types of aerogel and/or xerogel scaffolds have been demonstrated as effective sorbents for the capture and immobilization of radionuclides in gaseous form [e.g., iodine gas or I2(g), Xe] as well as ionic form (e.g., Ce4+, Cs+, I–, IO3-, Rb+, Sr2+, 99Tc7+, and U6+). These scaffolds have unique properties, which include high specific surface areas, high pore volumes, varieties of pore sizes, and functionalities that provide methods for binding radionuclides through physisorption, chemisorption, or a combination thereof. This combination of properties and functionalities make these types of materials ideal scaffolds for use as sorbents for capturing radionuclides. The primary base materials that will be discussed in this chapter include Ag0-functionalized silica aerogels, Ag+-impregnated aluminosilicate aerogels, Ag0-functionalized aluminosilicate aerogels, metal-impregnated (non-Ag) aluminosilicate aerogels and xerogels, sulfide-based aerogels, and carbon-based aerogel composites. For the capture of I2(g), the materials reported herein show some of the highest iodine loadings ever reported for inorganic sorbents. For the capture of ionic species, these materials also show promise to be some of the next generations of materials for active radionuclide remediation. This progress report will describe how these materials are fabricated, the general properties of these materials, as well as an overview of how they have been used for different applications in environmental remediation of radionuclides.

aerogel, xerogel, iodine, radionuclide remediation↗
DOE OSTI2020

Materials Data on Sb2Au(XeF6)2 by Materials Project

AuSb2(XeF6)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one AuSb2(XeF6)2 cluster. Xe is bonded in a single-bond geometry to one Au atom. The Xe–Au bond length is 2.77 Å. Au is bonded in a linear geometry to two equivalent Xe and two equivalent F atoms. Both Au–F bond lengths are 2.18 Å. Sb is bonded in an octahedral geometry to six F atoms. There are a spread of Sb–F bond distances ranging from 1.90–2.04 Å. There are six inequivalent F sites. In the first F site, F is bonded in a distorted bent 150 degrees geometry to one Au and one Sb atom. In the second F site, F is bonded in a single-bond geometry to one Sb atom. In the third F site, F is bonded in a single-bond geometry to one Sb atom. In the fourth F site, F is bonded in a single-bond geometry to one Sb atom. In the fifth F site, F is bonded in a single-bond geometry to one Sb atom. In the sixth F site, F is bonded in a single-bond geometry to one Sb atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Photoionization from the Xe 4d orbitals of XeF 2

Here, we present a comparison of the photoionization dynamics of the 4d shell of XeF 2 from threshold to 250 eV to those of the prototypical 4d shell of atomic Xe. The new experimental data include spin–orbit and ligand-field-resolved partial cross sections, photoelectron angular distributions, branching fractions, and lifetime widths for the 4d-hole states. The spin–orbit branching fractions and angular distributions are remarkably similar to the corresponding distributions from atomic Xe across a broad energy interval that includes both the intense shape resonance in the f continuum and a Cooper minimum in the same channel. The angular distributions and branching fractions are also in reasonably good agreement with our first-principles theoretical calculations on XeF 2 . Data are also presented on the lifetime widths of the substate-resolved 4d-hole states of XeF 2 . While the trends in the widths are similar to those in the earlier experimental and theoretical work, the linewidths are considerably smaller than in the previous measurements, which may require some reinterpretation of the decay mechanism. Finally, we present new data and an analysis of the Auger electron spectra for ionization above the 4d thresholds and resonant Auger spectra for several pre-edge features.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2003

The I-Xe Age of Orgueil Magnetite: New Results

I-Xe ages of Murchison and Orgueil magnetites were reported to be the oldest [1] and interpreted as the condensation time of the solar nebula. More recent measurements, conducted on a highly magnetic separate from Orgueil (but not pure magnetite), gave much younger I-Xe ages [2]. We have since performed new studies on two pure separates of Orgueil magnetite, confirming the later closing time of the I-Xe system in this mineral phase. In the previous work of Lewis and Anders [1] special attention was paid to the purity of the analyzed material. It was shown, that the trapped Xe resided mostly in hydrated silicates and the radiogenic 129Xe in magnetite [3]. Therefore, Orgueil was finely ground and stirred with a saturated LiCl solution for 8 days at 60 C to remove the silicate-magnetite intergrowth. Although this procedure yields magnetic fractions that are at least 90% pure [1], it could potentially contaminate the magnetite with iodine and produce noncorrelated 128Xe and spurious I-Xe ages. To avoid this possibility, in our first work with Orgueil we deliberately omitted separation in LiCl solution. Instead, the meteorite was ground into a fine powder and the highly magnetic fraction was separated with a hand magnet and was confirmed to be largely magnetite [2]. The new work, reported here, was done in order to confirm our previous results and investigate the effects of the LiCl treatment on the I-Xe system in magnetite.

Pravdivtseva, O. V.↗
NASA NTRS1986

The dating of pre-exposure times of lunar rocks and soils

Xenon produced by fission of uranium, thorium and plutonium has repeatedly been observed in lunar rocks and soils. In two basaltic rocks and in two soils Xe was found originating from fission of U-235 induced by neutrons which are due to the interactions of cosmic ray particles with lunar matter. Two facts lead to this conclusion: (1) fission Xe is present in excess of that expected for the U, Th, and Pu concentrations and for the gas retention age of the samples; and (2) the Xe-134/Xe-136 ratio of excess fission Xe is close to 1.25 as expected for neutron induced fission of U-235. Information on the duration of the exposure to cosmic rays was obtained from the Kr-81-Kr systematics whereas the effective shielding conditions were derived from the depth sensitive cosmogenic ratio Xe-131/Xe-126. For the four samples the exposure to cosmic rays in the lunar regolith is described by a two stage exposure model. The history of the four samples was derived in terms of duration and shielding depth of the two stages.

Eugster, O.↗
DOE OSTI2022

Report on Fuel Cycle Facility Requirements for Deployment of Demonstration Reactors and Potential Evolutionary Fuel Cycle Scenarios

A series of fuel cycle scenarios studies were performed to inform on fuel cycle capacities and facilities needed for large-scale deployment of the Advanced Reactor Demonstration Program (ARDP) reactors and potential future evolutionary fuel cycle scenarios. The reactor deployment and evolutionary fuel cycle scenarios from the present to 2100 were developed based on the following assumptions: 1) achievement of a net-zero emissions economy in the United States by 2050, which requires a nuclear energy generation capacity of ~250 GWe by 2050, 2) the U.S. economic growth of 1% per year from 2051 to 2100, which results in ~340 GWe of nuclear energy capacity in 2100, and 3) commercial-scale recycling and high burnup fuel technologies are available after 2050. Thus, evolutionary fuel cycles with those advanced nuclear technologies start after 2050. A single once-through fuel cycle scenario was assumed from the present to 2050 to achieve a net-zero emissions economy in the United States, and the following four evolutionary fuel cycle scenarios from 2051 to 2100 were considered, 1) Once through fuel cycle with ARDP reactors (Natrium and Xe-100), 2) Once-through fuel cycle with Breed-and-Burn (B&B) fast reactors, 3) Recycling fuel cycle of used metallic fuel in fast reactors, and 4) Recycle fuel cycle of both used uranium oxide and metallic fuels in fast reactors. The projected front-end and back-end fuel cycle capacity demands are compared with the current domestic and global (if needed) fuel cycle capacities.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Plasma Focused Ion Beam Milling of High-Aspect-Ratio Holes in Diamond

Plasma focused ion beam (PFIB) technology has a great potential for applications requiring rapid micro-machining of high-aspect-ratio features. Here, we use 30-keV Ar, Xe, and O 2 ion beams to study PFIB milling of high-aspect-ratio circular holes in polycrystalline diamond. Our results show that Xe and O 2 ion beams have the highest milling efficiency for low-aspect-ratio and high-aspect-ratio hole milling, respectively. Each ion beam species produces holes with its characteristic shape and wall surface morphology. In conclusion, based on these results, we demonstrate a “hybrid” hole milled in a two-step process with Xe and O 2 ion beams with the geometry and wall morphology attractive for the attachment of a fuel fill tube to the inertial confinement fusion capsule.

ICF targets↗
DOE OSTI2020

Materials Data on Na4XeO14 by Materials Project

Xe(Na2O7)2 crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional and consists of four xenon molecules and one Na2O7 framework. In the Na2O7 framework, there are two inequivalent Na sites. In the first Na site, Na is bonded in a 5-coordinate geometry to six O atoms. There are a spread of Na–O bond distances ranging from 2.34–3.03 Å. In the second Na site, Na is bonded in a 4-coordinate geometry to five O atoms. There are a spread of Na–O bond distances ranging from 2.26–2.98 Å. There are eight inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to two O atoms. There is one shorter (1.35 Å) and one longer (1.38 Å) O–O bond length. In the second O site, O is bonded in a bent 120 degrees geometry to two O atoms. There is one shorter (1.26 Å) and one longer (1.89 Å) O–O bond length. In the third O site, O is bonded in a distorted trigonal planar geometry to two Na and one O atom. In the fourth O site, O is bonded in a distorted T-shaped geometry to two Na and one O atom. The O–O bond length is 1.37 Å. In the fifth O site, O is bonded in a 4-coordinate geometry to two equivalent Na and two equivalent O atoms. In the sixth O site, O is bonded in a distorted see-saw-like geometry to three Na and one O atom. In the seventh O site, O is bonded in a distorted L-shaped geometry to two equivalent Na and two equivalent O atoms. In the eighth O site, O is bonded in a 3-coordinate geometry to two Na and one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuSb2(XeF5)4 by Materials Project

CuSb(Xe2F7)2SbF6 crystallizes in the tetragonal I-4 space group. The structure is one-dimensional and consists of two SbF6 clusters and two CuSb(Xe2F7)2 ribbons oriented in the (0, 0, 1) direction. In each SbF6 cluster, Sb is bonded in an octahedral geometry to six F atoms. There is four shorter (1.92 Å) and two longer (1.93 Å) Sb–F bond length. There are two inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Sb atom. In the second F site, F is bonded in a single-bond geometry to one Sb atom. In each CuSb(Xe2F7)2 ribbon, Xe is bonded in a linear geometry to two F atoms. There are one shorter (2.02 Å) and one longer (2.18 Å) Xe–F bond lengths. Cu is bonded to six F atoms to form CuF6 octahedra that share corners with two equivalent SbF6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (1.93 Å) and two longer (2.30 Å) Cu–F bond lengths. Sb is bonded to six F atoms to form SbF6 octahedra that share corners with two equivalent CuF6 octahedra. The corner-sharing octahedral tilt angles are 0°. There is four shorter (1.91 Å) and two longer (1.95 Å) Sb–F bond length. There are four inequivalent F sites. In the first F site, F is bonded in a bent 120 degrees geometry to one Xe and one Cu atom. In the second F site, F is bonded in a single-bond geometry to one Xe atom. In the third F site, F is bonded in a single-bond geometry to one Sb atom. In the fourth F site, F is bonded in a linear geometry to one Cu and one Sb atom.

36 MATERIALS SCIENCE↗