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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on U(SiOs)2 by Materials Project

U(OsSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. U4+ is bonded in a 8-coordinate geometry to eight equivalent Os2- atoms. All U–Os bond lengths are 3.17 Å. Os2- is bonded in a 4-coordinate geometry to four equivalent U4+ and four equivalent Si atoms. All Os–Si bond lengths are 2.40 Å. Si is bonded in a 5-coordinate geometry to four equivalent Os2- and one Si atom. The Si–Si bond length is 2.37 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(CoP)2 by Materials Project

UCo2P2 crystallizes in the tetragonal P4mm space group. The structure is three-dimensional. there are two inequivalent U3+ sites. In the first U3+ site, U3+ is bonded in a 8-coordinate geometry to eight P3- atoms. There are four shorter (2.95 Å) and four longer (2.97 Å) U–P bond lengths. In the second U3+ site, U3+ is bonded in a 8-coordinate geometry to eight P3- atoms. There are four shorter (2.94 Å) and four longer (2.97 Å) U–P bond lengths. There are three inequivalent Co+1.50+ sites. In the first Co+1.50+ site, Co+1.50+ is bonded in a 5-coordinate geometry to five P3- atoms. There are four shorter (2.21 Å) and one longer (2.24 Å) Co–P bond lengths. In the second Co+1.50+ site, Co+1.50+ is bonded in a 5-coordinate geometry to five P3- atoms. There are four shorter (2.21 Å) and one longer (2.22 Å) Co–P bond lengths. In the third Co+1.50+ site, Co+1.50+ is bonded to four P3- atoms to form a mixture of edge and corner-sharing CoP4 tetrahedra. There are two shorter (2.29 Å) and two longer (2.31 Å) Co–P bond lengths. There are three inequivalent P3- sites. In the first P3- site, P3- is bonded in a 9-coordinate geometry to four equivalent U3+ and five Co+1.50+ atoms. In the second P3- site, P3- is bonded in a 4-coordinate geometry to four U3+ and four Co+1.50+ atoms. In the third P3- site, P3- is bonded in a 9-coordinate geometry to four equivalent U3+ and five Co+1.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(OF)2 by Materials Project

UO2F2 crystallizes in the monoclinic C2/m space group. The structure is one-dimensional and consists of two UO2F2 ribbons oriented in the (0, 1, 0) direction. U6+ is bonded to four equivalent O2- and two equivalent F1- atoms to form distorted edge-sharing UO4F2 octahedra. All U–O bond lengths are 2.08 Å. Both U–F bond lengths are 2.09 Å. O2- is bonded in a distorted water-like geometry to two equivalent U6+ atoms. F1- is bonded in a single-bond geometry to one U6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(WC)4 by Materials Project

UW4C4 crystallizes in the tetragonal P4/m space group. The structure is three-dimensional. there are two inequivalent U4+ sites. In the first U4+ site, U4+ is bonded in a body-centered cubic geometry to eight equivalent C4- atoms. All U–C bond lengths are 2.57 Å. In the second U4+ site, U4+ is bonded in a body-centered cubic geometry to eight equivalent C4- atoms. All U–C bond lengths are 2.50 Å. There are two inequivalent W3+ sites. In the first W3+ site, W3+ is bonded in a rectangular see-saw-like geometry to four C4- atoms. There are a spread of W–C bond distances ranging from 2.15–2.19 Å. In the second W3+ site, W3+ is bonded to four C4- atoms to form corner-sharing WC4 trigonal pyramids. There are a spread of W–C bond distances ranging from 2.08–2.11 Å. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded to two equivalent U4+ and four W3+ atoms to form a mixture of corner, edge, and face-sharing CU2W4 octahedra. The corner-sharing octahedra tilt angles range from 0–68°. In the second C4- site, C4- is bonded to two equivalent U4+ and four W3+ atoms to form a mixture of corner, edge, and face-sharing CU2W4 octahedra. The corner-sharing octahedra tilt angles range from 0–67°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(BiO2)4 by Materials Project

U(BiO2)4 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. U4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (2.30 Å) and four longer (2.41 Å) U–O bond lengths. There are two inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.34–2.47 Å. In the second Bi3+ site, Bi3+ is bonded to six O2- atoms to form a mixture of distorted corner and edge-sharing BiO6 octahedra. The corner-sharing octahedral tilt angles are 59°. There are a spread of Bi–O bond distances ranging from 2.28–2.50 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the second O2- site, O2- is bonded to four equivalent Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the third O2- site, O2- is bonded to two equivalent U4+ and two equivalent Bi3+ atoms to form a mixture of corner and edge-sharing OU2Bi2 tetrahedra. In the fourth O2- site, O2- is bonded to two equivalent U4+ and two equivalent Bi3+ atoms to form OU2Bi2 tetrahedra that share corners with fourteen OBi4 tetrahedra and edges with five OU2Bi2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(WO4)2 by Materials Project

U(WO4)2 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. U4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of U–O bond distances ranging from 2.31–2.46 Å. There are two inequivalent W6+ sites. In the first W6+ site, W6+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.81 Å) and two longer (1.82 Å) W–O bond length. In the second W6+ site, W6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of W–O bond distances ranging from 1.81–1.85 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one W6+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one W6+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one W6+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one W6+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one W6+ atom. In the sixth O2- site, O2- is bonded in a distorted linear geometry to one U4+ and one W6+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one W6+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one U4+ and one W6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(PO3)4 by Materials Project

U(PO3)4 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. U4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of U–O bond distances ranging from 2.33–2.41 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one U4+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a linear geometry to two P5+ atoms. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to one U4+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to one U4+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to one U4+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(WC)4 by Materials Project

UW4C4 crystallizes in the tetragonal P4/m space group. The structure is three-dimensional. there are two inequivalent U4+ sites. In the first U4+ site, U4+ is bonded in a body-centered cubic geometry to eight equivalent C4- atoms. All U–C bond lengths are 2.49 Å. In the second U4+ site, U4+ is bonded in a body-centered cubic geometry to eight equivalent C4- atoms. All U–C bond lengths are 2.53 Å. There are two inequivalent W3+ sites. In the first W3+ site, W3+ is bonded to four C4- atoms to form corner-sharing WC4 trigonal pyramids. There are one shorter (2.09 Å) and three longer (2.11 Å) W–C bond lengths. In the second W3+ site, W3+ is bonded in a rectangular see-saw-like geometry to four C4- atoms. There are a spread of W–C bond distances ranging from 2.13–2.16 Å. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded to two equivalent U4+ and four W3+ atoms to form a mixture of edge, face, and corner-sharing CU2W4 octahedra. The corner-sharing octahedra tilt angles range from 0–67°. In the second C4- site, C4- is bonded to two equivalent U4+ and four W3+ atoms to form a mixture of edge, face, and corner-sharing CU2W4 octahedra. The corner-sharing octahedra tilt angles range from 0–68°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(BO2)4 by Materials Project

U(BO2)4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. U4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of U–O bond distances ranging from 2.31–2.56 Å. There are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.45–1.54 Å. In the second B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.45–1.53 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent U4+ and one B3+ atom. In the second O2- site, O2- is bonded in a trigonal planar geometry to three B3+ atoms. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one U4+ and two B3+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one U4+ and two B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(BOs)4 by Materials Project

U(OsB)4 crystallizes in the tetragonal I4_1/acd space group. The structure is three-dimensional. U6+ is bonded in a 12-coordinate geometry to twelve equivalent Os+1.50- atoms. There are a spread of U–Os bond distances ranging from 2.93–3.27 Å. Os+1.50- is bonded in a 5-coordinate geometry to three equivalent U6+ and five equivalent B atoms. There are a spread of Os–B bond distances ranging from 2.16–2.28 Å. B is bonded in a 6-coordinate geometry to five equivalent Os+1.50- and one B atom. The B–B bond length is 1.77 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(SO4)2 by Materials Project

U(SO4)2 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. U4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of U–O bond distances ranging from 2.32–2.43 Å. There are two inequivalent S6+ sites. In the first S6+ site, S6+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.48 Å) and two longer (1.49 Å) S–O bond length. In the second S6+ site, S6+ is bonded in a tetrahedral geometry to four O2- atoms. There is one shorter (1.48 Å) and three longer (1.49 Å) S–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one U4+ and one S6+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one S6+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one S6+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one S6+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one U4+ and one S6+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one S6+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to one U4+ and one S6+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one S6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(PS3)4 by Materials Project

U(PS3)4 is I4/mcm-derived structured and crystallizes in the tetragonal I4_1/a space group. The structure is three-dimensional. U4+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are four shorter (2.84 Å) and four longer (2.88 Å) U–S bond lengths. P5+ is bonded to four S2- atoms to form edge-sharing PS4 tetrahedra. There are a spread of P–S bond distances ranging from 2.01–2.15 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted L-shaped geometry to one U4+ and one P5+ atom. In the second S2- site, S2- is bonded in an L-shaped geometry to two equivalent P5+ atoms. In the third S2- site, S2- is bonded in a distorted L-shaped geometry to one U4+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(NiAs)2 by Materials Project

U(NiAs)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. U3+ is bonded in a 8-coordinate geometry to eight As3- atoms. There are four shorter (3.12 Å) and four longer (3.13 Å) U–As bond lengths. There are two inequivalent Ni+1.50+ sites. In the first Ni+1.50+ site, Ni+1.50+ is bonded to four equivalent As3- atoms to form a mixture of edge and corner-sharing NiAs4 tetrahedra. All Ni–As bond lengths are 2.41 Å. In the second Ni+1.50+ site, Ni+1.50+ is bonded in a 5-coordinate geometry to five As3- atoms. There are one shorter (2.30 Å) and four longer (2.35 Å) Ni–As bond lengths. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a 4-coordinate geometry to four equivalent U3+ and four equivalent Ni+1.50+ atoms. In the second As3- site, As3- is bonded in a 5-coordinate geometry to four equivalent U3+ and five Ni+1.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(CuAs)2 by Materials Project

U(CuAs)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. U4+ is bonded to six equivalent As3- atoms to form UAs6 octahedra that share corners with twelve equivalent CuAs4 tetrahedra, edges with six equivalent UAs6 octahedra, and edges with six equivalent CuAs4 tetrahedra. All U–As bond lengths are 2.88 Å. Cu1+ is bonded to four equivalent As3- atoms to form CuAs4 tetrahedra that share corners with six equivalent UAs6 octahedra, corners with six equivalent CuAs4 tetrahedra, edges with three equivalent UAs6 octahedra, and edges with three equivalent CuAs4 tetrahedra. The corner-sharing octahedra tilt angles range from 18–55°. There are three shorter (2.45 Å) and one longer (2.50 Å) Cu–As bond lengths. As3- is bonded to three equivalent U4+ and four equivalent Cu1+ atoms to form a mixture of distorted corner and edge-sharing AsU3Cu4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(PO3)4 by Materials Project

U(PO3)4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. U4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of U–O bond distances ranging from 2.22–2.53 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of P–O bond distances ranging from 1.47–1.51 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form edge-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.66 Å. In the third P5+ site, P5+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of P–O bond distances ranging from 1.47–1.52 Å. In the fourth P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of P–O bond distances ranging from 1.47–1.80 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one U4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one U4+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the eighth O2- site, O2- is bonded in an L-shaped geometry to two equivalent P5+ atoms. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to one U4+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted single-bond geometry to one U4+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one U4+ and one P5+ atom.

36 MATERIALS SCIENCE↗
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 OSTI2025

Impact of U-10Mo HALEU fuel element tolerances on the Massachusetts Institute of Technology reactor safety and operational performance – Thermal hydraulics

The U.S. is coordinating efforts for the conversion of six U.S. High Performance Research Reactors (USHPRR) including one critical facility from highly enriched uranium (HEU) to low-enriched uranium (LEU). In order to continue the mission of these reactors, including the Massachusetts of Institute of Technology Reactor (MITR), and achieve similar performance, high-assay low-enriched uranium (HALEU) with a high-density metallic alloy of uranium with 10 wt% molybdenum (U-10Mo) is being evaluated. The impact of the fabrication specification and tolerances was assessed following the preliminary design of the MITR LEU fuel elements using the U-10Mo monolithic alloy. This research focuses on the analysis of fabrication specification impact on thermal hydraulics (TH) characteristic of the MITR LEU core as a function of the variation of the relevant fuel specification parameters (e.g., coolant channel gap thickness, fuel plate thickness, etc.). The analyses are performed based on an all-fresh LEU fuel conversion plan identified in a preliminary safety analysis report submitted to the Nuclear Regulatory Commission. The reactor power margin to the onset of nucleate boiling (ONB) is assessed under the limiting safety system settings (LSSS), where a scram occurs, to ensure there is sufficient margin to the reactor safety limit, which is defined by the onset of flow instability that occurs after the ONB. The best estimate plus uncertainty approach is employed to analyze this TH characteristic, which yields realistic results while maintaining adequate conservatism, utilizing a statistical uncertainty propagation method with the STAT7 code. The TH characteristic is analyzed as a function of the variability of the specification parameters resulting from the fabrication process. The main findings of this study show that the MITR core can meet the TH safety and operational requirements at the all-LEU initial core startup (cycle 1), selected transition cycles (most reactive cycle and most limiting cycle: cycle 3 and 5, respectively) and equilibrium (cycle 14) cores under all limiting fabrication parameter combinations considered. In addition, the analyses show that the dependency of the core power margin to ONB on those specification parameters that have the most direct impact on TH performance is non-linear but monotonically decreasing within the specification tolerances. The third order polynomial fit curves are reported in detail for selected limiting cases and can serve as a powerful tool for future MITR fuel management in cases such as when HALEU supply is established that may allow additional cycle length or other operational benefits.

Conversion↗
DOE OSTI2024

Development of real-time density feedback control on MAST-U in L-mode

In this paper we report on the development and demonstration of density feedback control for MAST-U. Sinusoidal perturbations are used to measure the frequency response from a deuterium gas valve (actuator) to line-integrated core electron density measured by the interferometer (sensor). In the frequency range relevant for control design, only two system-identification experiments were needed to regress a first-order dynamic model. This control-oriented model informs the offline design of a proportional integral controller with the established loop-shaping controller design method. After offline verification of the controller implementation, control is demonstrated by experimentally tracking a staircase reference for the line-integrated electron density. This paper demonstrates the efficiency of controller design using system-identification and loop-shaping, providing reliable density control for MAST-U.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗