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All sourcesNASA NTRSDOE OSTI
NASA NTRS2026

Barium Fluoride as a Standard Reference Material for Infrared Refractometry

This work proposes a standard reference material (SRM) for measurements of refractive index in the infrared spectral region (1–12 μm). The purpose of this material is to enable cross-method comparison of refractive index data obtained through minimum deviation, ellipsometry, interferometry, and prism coupling techniques. This will allow vendors and metrology laboratories, regardless of which technique they employ, to certify that their measurements meet required levels of accuracy, precision, and repeatability. Drawing on foundational work by Tilton at the National Bureau of Standards, a figure of merit for candidate SRM materials is outlined, and three materials are selected for further evaluation. Ultimately, barium fluoride is proposed as the most suitable SRM for the infrared spectral region, based on its broad transmission range, chemical and mechanical stability, low temperature dependence of refractive index, and well-characterized dispersion behavior.

Andrew Howe↗
DOE OSTI2014

Fluoride Salt-Cooled High-Temperature Reactor Development Roadmap

Fluoride salt-cooled high-temperature reactors (FHRs) are an emerging reactor class with potentially advantageous performance characteristics and fully passive safety. This paper provides an overview of a technology development pathway for expeditious commercial deployment of first-generation FHRs. The paper describes the principal remaining FHR technology challenges and the development path needed to address the challenges. First-generation FHRs do not appear to require any technology breakthroughs, but will require significant technology development and demonstration. FHRs are currently entering early phase engineering development. As such, the development roadmap is not as technically detailed or specific as would be the case for a more mature reactor class. The higher cost of fuel and coolant; the lack of an approved licensing framework; the lack of qualified, salt-compatible structural materials; and the potential for tritium release into the environment are the most obvious issues that remain to be resolved.

Holcomb, David Eugene↗
DOE OSTI2015

Ferroelectric fluoride compositions and methods of making and using same

A method for synthesis of a ferroelectric material characterized by the general formula A.sub.xB.sub.yF.sub.z where A is an alkaline earth metal, B is transition metal or a main group metal, x and y each range from about 1 to about 5, and z ranges from about 1 to about 20 comprising contacting an alkaline earth metal fluoride, a difluorometal compound and a fluoroorganic acid in a medium to form a reaction mixture; and subjecting the reaction mixture to conditions suitable for hydrothermal crystal growth.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Thermal-Hydraulic Design of a Fluoride High-Temperature Demonstration Reactor

INTRODUCTION The Fluoride High-Temperature Reactor (FHR) named the Demonstration Reactor (DR) is a novel reactor concept using molten salt coolant and TRIstructural ISOtropic (TRISO) fuel that is being developed at Oak Ridge National Laboratory (ORNL). The objective of the FHR DR is to advance the technology readiness level of FHRs. The FHR DR will demonstrate technologies needed to close remaining gaps to commercial viability. The FHR DR has a thermal power of 100 MWt, very similar to the SmAHTR, another FHR ORNL concept (Refs. 1 and 2) with a power of 125 MWt. The FHR DR is also a small version of the Advanced High Temperature Reactor (AHTR), with a power of 3400 MWt, cooled by a molten salt and also being developed at ORNL (Ref. 3). The FHR DR combines three existing technologies: (1) high-temperature, low-pressure molten salt coolant, (2) high-temperature coated-particle TRISO fuel, (3) and passive decay heat cooling systems by using Direct Reactor Auxiliary Cooling Systems (DRACS). This paper presents FHR DR thermal-hydraulic design calculations.

High-temperature↗
DOE OSTI2016

Core Design Characteristics of the Fluoride Salt-Cooled High Temperature Demonstration Reactor

Fluoride salt-cooled high temperature reactors (FHRs) are a promising reactor technology option with significant knowledge gaps to implementation. One potential approach to address those technology gaps is via a small-scale demonstration reactor with the goal of increasing the technology readiness level (TRL) of the overall system for the longer term. The objective of this paper is to outline a notional concept for such a system, and to address how the proposed concept would advance the TRL of FHR concepts.Development of the proposed FHR Demonstration Reactor (DR) will enable commercial FHR deployment through disruptive and rapid technology development and demonstration. The FHR DR will close remaining gaps to commercial viability. Lower risk technologies are included in the initial FHR DR design to ensure that the reactor can be built, licensed, and operated within an acceptable budget and schedule. Important capabilities that will be demonstrated by building and operating the FHR DR include core design methodologies; fabrication and operation of high temperature reactors; salt procurement, handling, maintenance, and ultimate disposal; salt chemistry control to maximize vessel life; tritium management; heat exchanger performance; pump performance; and reactivity control. The FHR DR is considered part of a broader set of FHR technology development and demonstration efforts, some of which are already underway. Nonreactor test efforts (e.g., heated salt loops or loops using simulant fluids) can demonstrate many technologies necessary for commercial deployment of FHRs. The FHR DR, however, fulfills a crucial role in FHR technology development by advancing the technical maturity and readiness level of the system as a whole.

Brown, Nicholas↗
DOE OSTI2016

Phenomena Identification and Ranking Table (PIRT) for Fluoride High-Temperature Reactor (FHR) Neutronics

The deployment of Fluoride (salt-cooled) High Temperature Reactors (FHRs) has many potential benefits such as improved safety, improved economics, and a diversification of the energy portfolio because of its capability to supply industrial process heat. However, significant challenges remain before this class of reactors can be deployed, mostly related to its technology readiness. A recent study identified several areas in need of further development in order to advance the technology. These include the verification and validation of neutronics and thermal hydraulics modeling and simulation tools in support of design, safety analysis and licensing. The focus of this paper is to summarize the issues for verification and validation of neutronics tools. Current tools for neutronics analysis of LWRs are inadequate for the simulation of salt cooled reactors. The methodologies developed for the high temperature gas cooled reactors (HTGRs) have some relevance for FHRs because of the similarities between the two reactors such as graphite block structure, encapsulated fuel particles, and high operating temperatures. However, they are not sufficient for the accuracy desired of a code for licensing as they have a number of important differences neutronically, such as the use of liquid salt containing beryllium as a coolant and their unique fuel configuration.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2018

Muon Anomalous Precession Frequency Measurement Using Lead Fluoride Calorimeters in the Muon g-2 Experiment

aThe Standard Model (SM) of particle physics has been strikingly successful in explaining a wide range of physical phenomena and almost all experimental results. One of the most significant discrepancies at present is the anomalous magnetic moment $a_\mu$=(g−2)/2 of the muon, which was measured by the E821 collaboration at BNL in 2004 to be more than three-standard-deviation greater than the SM prediction. Various models beyond SM physics have been proposed to explain this discrepancy, but the key to resolving this tension remains a more precise measurement of $a_{\mu}$. The Muon g-2 collaboration at Fermilab aims to measure $a_{\mu}$ with a precision goal of 140 parts per billion, a fourfold improvement over BNL's result. If the central values of the experimental result and the theoretical prediction remain unchanged, the discrepancy will exceed seven standard deviations which a clear indication of physics beyond SM. In this poster, preliminary results from th e ongoing physics data taking will be presented, especially on the measurement of the muon anomalous precession frequency using lead fluoride calorimeters. Energy calibration and timing alignment procedures of calorimeter channels will also be described, and their impact on high-level analyses will be discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Molten Salt Tritium Transport Experiment: A Versatile Fluoride Salt Loop for Validation of Tritium Transport Phenomena

Tritium is generated in Molten Salt Reactors (MSRs) from neutron capture by lithium and other constituents of the molten salt FLiBe. Tritium is a unique radionuclide as it readily permeates through hot structural materials. Thus, any material in contact with tritium laden molten salt is a potential pathway for release. Understanding tritium transport and devising adequate control strategies is necessary for the safe operation of MSRs. The Molten Salt Tritium Transport Experiment (MSTTE) is a forced-convection fluoride salt loop with the capability to inject hydrogen isotopes into flowing molten salt and to measure transport phenomena such as permeation through metals and evolution from free-surfaces. MSTTE is designed to be versatile to test potential control technology in future campaigns. This report focuses on the current design and analysis of MSTTE. Custom designed and fabricated experiment components such as the hydrogen injection system, permeation test section, diagnostics, and gas distribution system are discussed in detail. System-level tritium transport modeling using the System Analysis Module investigates experiment parameters such as hydrogen source terms, salt flow rate, and salt temperature. Computational fluid dynamics of the salt flow in the permeation test section informs design choices to establish fully developed flow in the measured permeation zone.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2022

Neutronic design and fuel cycle analysis of a fluoride salt-cooled High Temperature Reactor (FHR)

The Fluoride salt-cooled High temperature Reactor (FHR) is a new Gen IV reactor concept that can operate under near atmospheric pressure circumstances and further enhance the inherent safety. In this study, an FHR core design with 165 megawatts of thermal output (MWth) is proposed. The reactor core employs tri-structural-isotropic (TRISO) particle fuel within prismatic graphite blocks as the basic fuel form, FLiBe (2 {sup 7}LiF-BeF{sub 2}) as the primary coolant, and a three-batch fuel cycle scheme. Sensitivity analyses on various parameters were performed to optimize the cycle length and neutronic parameters. The fuel cycle of this core design was evaluated in detail from 4 aspects: cycle length, power peaking factor (PPF), discharge burnup, and temperature coefficient. It was found that larger fuel channel pitch (FCP) would have a relatively harder neutron spectrum, and yield relatively longer cycle length, lower, better fuel temperature coefficient (FTC), and moderator temperature coefficient (MTC). In addition, burnable poison (BP), Er{sub 2}O{sub 3}, can effectively reduce PPF, hold down the multiplication factor, and more importantly it can improve the MTC. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2015

Planar fluoride waveguides for amplifiers and lasers

We have produced planar optical waveguides having a crystalline CaF{sub 2} – YF{sub 3} – NdF{sub 3} mixed yttrofluorite core and two reflective claddings in order to improve waveguide excitation efficiency. Under diode pumping, lasing has been achieved at a wavelength of 1064 nm with a slope efficiency near 15%. (lasers)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

High pressure phase transitions in scheelite structured fluoride: ErLiF{sub 4}

Our synchrotron based angle dispersive x-ray diffraction studies on scheelite structured ErLiF{sub 4} show that it undergoes two phase transitions, at ~11.5 and ~15.5 GPa to lower symmetry monoclinic phases, before becoming (irreversibly) amorphous at ~28 GPa. The first high pressure phase transformation to the fergusonite structure (space group I2/a) is found to be of thermodynamically second order. The second high pressure phase could be fitted to the P2/c space group, but detailed analysis rules out the wolframite structure (P2/c space group), common to many scheelite compounds under high pressures. We also suggest that despite the ionic character of the LiF{sub 4} tetrahedra, the compressibility of LnLiF{sub 4} (Ln=Eu–Lu) kind of scheelites is more affected by the LnF{sub 8} dodecahedra than the LiF{sub 4} tetrahedra. - Graphical abstract: Volume per formula unit of the scheelite and high pressure phases of ErLiF{sub 4} as a function of pressure. - Highlights: • ErLiF{sub 4} transforms to fergusonite and P2/c phase at high pressure. • Polyhedra of LnF{sub 8} affects compressibility of LnLiF{sub 4} (Ln=Eu–Lu) more than LiF{sub 4}. • Amorphization pressure varies inversely in LnLiF{sub 4} with ionic size of Ln cation. • In ErLiF{sub 4}a/c ratio reduces with pressure in contrast to reported increase in YLiF{sub 4}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Frequency non-degenerate sequential excitation of the impurity trapped exciton in strontium fluoride crystals doped with ytterbium

We model the dynamic behaviour observed for impurity-trapped excitons in SrF{sub 2}:Yb{sup 2+} using transient photoluminescence enhancement induced via a two-frequency, sequential excitation process employing an UV optical parametric amplifier synchronized to an IR free electron laser (FEL). We observe sharp transitions interpreted as a change of state of the localized hole and broad bands interpreted as a change of state of the delocalized electron. Our modeling indicates that the 4f crystal-field interaction is 25% smaller than in CaF{sub 2}. The photoluminescence enhancement transients are analyzed across a range of excitation frequencies using a system of rate equations. The temporal behavior is explained in terms of intra-excitonic relaxation, local lattice heating by the FEL, and liberation of electrons from trap states.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

The Role of Electrolyte Composition in Enabling Li Metal‐Iron Fluoride Full‐Cell Batteries

Abstract FeF 3 conversion cathodes, paired with Li metal, are promising for use in next‐generation secondary batteries and offer a remarkable theoretical energy density of 1947 Wh kg −1 compared to 690 Wh kg −1 for LiNi 0.5 Mn 1.5 O 4 ; however, many successful studies on FeF 3 cathodes are performed in cells with a large (>90‐fold) excess of Li that disguises the effects of tested variables on the anode and decreases the practical energy density of the battery. Herein, it is demonstrated that for full‐cell compatibility, the electrolyte must produce both a protective solid‐electrolyte interphase and cathode‐electrolyte interphase and that an electrolyte composed of 1:1.3:3 (m/m) LiFSI, 1,2‐dimethoxyethane, and 1,1,2,2‐tetrafluoroethyl‐2,2,3,3‐tetrafluoropropyl ether fulfills both these requirements. This work demonstrates the importance of verifying electrode level solutions on the full‐cell level when developing new battery chemistries and represents the first full cell demonstration of a Li/FeF 3 cell, with both limited Li and high capacity FeF 3 utilization.

25 ENERGY STORAGE↗
DOE OSTI2016

Lithium Fluoride Additives for Stable Cycling of Lithium Batteries at High Current Densities

The addition of LiF salt to a lithium battery electrolyte improves the surface diffusion of ions on the electrode surface, which leads to smooth electrodeposition. It also forms a protective layer on the electrode that prevents degradation of electrolyte by side reactions. This LiF additive can be effective in improving the capacity and lifetime of a commercial lithium metal battery.

25 ENERGY STORAGE↗
DOE OSTI2019

Uncovering Multiple Metal-Metal Bonding in a Tetranuclear Fluoride Rhenium Cluster or the Curious Case of {[Ni(H 2 O) 6 ](NH 4 ) 4 }[Re 4 F 18 ]·4H 2 O

The compound {[Ni(H 2 O) 6 ](NH 4 ) 4 }[Re 4 F 18 ]·4H 2 O (1) has been isolated and characterized by single-crystal X-ray diffraction, Raman spectroscopy and computational methods. The compound 1 crystallizes in the triclinic space group P 1 (a = 6.6620(9) Å, b = 9.7121(13) Å, c = 11.2007(15) Å, α = 67.644(2)°, β = 83.827(2)°, γ = 84.366(2)°). In 1, the [Re 4 F 18 ] 6– anion is composed of four Re(III) atoms bridged by two µ-bridging fluorine atoms and two di-µ-bridging fluorine atoms. Furthermore, in [Re 4 F 18 ] 6– , the shortest Re–Re distance (i.e., 2.3631(6) Å) is characteristic of the presence of a Re=Re double bond; the Re–F distances range from 1.854(6) to 2.008(5) Å. Theoretical calculations confirm the presence of a weak Re=Re double bond; the Mayer–Mulliken bond order of the doubly bridged Re atoms is 1.8097 and the natural localized molecular orbital bond order is 1.8751. The Raman spectrum of 1 has been measured and shows a series of bands in the region 167–1449 cm –1 that have been attributed to Re–F and Ni–O stretches, Re 4 F 18 ring breathing and NH 4 + bending and libration modes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

{sup 18}F-sodium fluoride positron emission tomography assessed microcalcifications in culprit and non-culprit human carotid plaques

Background: {sup 18}F-NaF positron emission tomography (PET) targets microcalcifications. We compared in vitro microPET assessed {sup 18}F-NaF uptake between culprit and non-culprit human carotid plaques. Furthermore, we compared {sup 18}F-NaF uptake with calcification visualized on microcomputed tomography (microCT). Methods: Carotid plaques from stroke patients undergoing surgery were incubated in {sup 18}F-NaF and scanned using a microPET and a microCT scan. The average PET assessed {sup 18}F-NaF uptake was expressed as percentage of the incubation dose per gram (%Inc/g). {sup 18}F-NaF PET volume of interest (VOI) was compared with CT calcification VOI. Results: 23 carotid plaques (17 culprit, 6 non-culprit) were included. The average {sup 18}F-NaF uptake in culprit carotid plaques was comparable with the uptake in non-culprit carotid plaques (median 2.32 %Inc/g [IQR 1.98 to 2.81] vs. median 2.35 %Inc/g [IQR 1.77 to 3.00], P = 0.916). Only a median of 10% (IQR 4 to 25) of CT calcification VOI showed increased {sup 18}F-NaF uptake, while merely a median of 35% (IQR 6 to 42) of {sup 18}F-NaF PET VOI showed calcification on CT. Conclusions: {sup 18}F-NaF PET represents a different stage in the calcification process than CT. We observed a similar PET assessed {sup 18}F-NaF uptake and pattern in culprit and non-culprit plaques of high-risk patients, indicating that this method may be of more value in early atherosclerotic stenosis development. [French] French Abstract: Contexte: La tomographie par émission de positons (TEP) au {sup 18}F-NaF marque les micro-calcifications. Nous avons comparé in vitro les plaques carotidiennes humaines responsable d’accident vasculaire cérébrales marquées au {sup 18}F-NaF avec une microTEP et leur calcification au moyen d’un microCT Méthodes: Les plaques carotidiennes de patients victimes d’un accident vasculaire cérébral qui ont bénéficié d’ une intervention chirurgicale ont été incubées dans du {sup 18}F-NaF et imagées avec une microTEP et un microCT. Le pourcentage d’absorption moyen de {sup 18}F-NaF par gr de tissu (% Inc/g) ont été comparées au volume d’intérêt (VOI) des calcifications mesurées par CT. Résultats: 23 plaques carotidiennes (17 responsables d’un AVC et 6 non responsables) ont été incluses. Le % moyen d’absorption de {sup 18}F-NaF dans les plaques carotidiennes responsables furent comparable à l’absorption dans les plaques non responsables (2,32% Inc/g vs 2,35% Inc/g , p = 0,916). Dix pourcent seulement des calcifications visualisées par CT démontrèrent une augmentation d’absorption de {sup 18}F-NaF et 35% des plaques montrant une absorption de {sup 18}F-NaF PET VOI démontrèrent des calcifications au CT. Conclusions: L’imagerie de l’absorption de {sup 18}F-NaF par tomographie à positrons représente un processus physiopathologique différent de l’imagerie des calcifications par CT. L’absorption du {sup 18}F-NaF par les plaques responsables et non responsables d’accidents vasculaire cérébraux pourrait s’avérer utile dans le diagnostic précoce des sténoses athéromateuses. [Spanish] Spanish Abstract: Antecedentes: La tomografía por emisión de positrones (PET) con {sup 18}F-floruro de sodio ({sup 18}F-NaF) demuestra microcalcificaciones. En este estudio, comparamos la captación de {sup 18}F-NaF entre placas carotideas culpables y no culpables valorada con microPET in vitro. Además, comparamos la captación de {sup 18}F-NAF con las calcificaciones detectadas por microtomografía computada (microCT). Métodos: Placas carotídeas de pacientes postoperados que sufrieron de un evento vascular cerebral fueron incubadas en 18-NaF y escaneadas usando microPET y microCT. El promedio de la captación fue expresado como porcentaje de la dosis de incubación por gramo (%Inc/gr). El volumen de interés (VOI) del PET {sup 18}F-NaF se comparó con el VOI de calcificación por CT. Resultados: Se incluyeron 23 placas carotídeas (17 culpables y 6 no culpables). El promedio de la captación de {sup 18}F-NaF en placas carotídeas culpable fue comparable al de las placas no culpables. (mediana 2.32%Inc/gr [IQR1.98-2.81] vs. mediana 2.35%Inc/gr [IQR1.77-3], p=.916). Solo una mediana de 10% (IQR 4-25) del VOI en CT mostró un aumento en la captación de {sup 18}F-NaF, mientras una mediana de 35% (IQR 6-42) del VOI de PET {sup 18}F-NaF mostró calcificación en CT. Conclusiones: La tomografía por emisión de positrones con {sup 18}F-NaF evalúa una etapa distinta en el proceso de calcificación que la CT. El patrón de captación de {sup 18}F-NaF que observamos en este estudio fue similar entre placas culpables y no culpables de pacientes de alto riesgo, lo cual indica que este método puede ser de mayor valor en el desarrollo temprano de la estenosis ateroesclerótica. [Chinese] Chinese Abstract: 背景: F18 氟化钠正电子发射断层扫描 (PET) 可用于检测微钙化。我们使用微型 PET 来评估病人体外 F18 氟化钠在颈动脉罪犯和非罪犯斑块之间的的摄取区别。此外, 我们还将 F18 氟化钠的摄取与 microCT 扫描检测的钙化进行对比。 方法: 将接受手术的中风患者的颈动脉斑块在 F18 氟化钠中培养并用 microPE 和 microCT 进行扫描。PET 对 F18 氟化钠的平均摄取率表示为每克培养剂量的百分比。F18 氟化钠 PET 中的感兴趣区域和 CT 钙化图像中的感兴趣区域 (VOI) 进行比较。 结果: 一共有 23个颈动脉斑块, 其中 17个罪犯斑块和 6个非罪犯斑块。罪犯和非罪犯颈动脉斑块的 F18 氟化钠的平均摄取率无明显差异 (中值 2.32 % Inc/g [IQR 1.98-2.81] vs. 中值2.35 % Inc/g [IQR 1.77-3.00], p = 0.916)。仅中值为10% [IQR 4-25] 的 CT 钙化 VOI 显示有F18氟化钠的摄取增加, 中值为 35%[IQR 6-42] 的 F18 氟化钠 PET VOI 显示有CT 上的钙化。 结论: 相较于 CT, F18 氟化钠 PET 展现了钙化过程中的一个不同阶段。在高危病人中, 我们观察到罪犯和非罪犯斑块具有类似的 PET F18 氟化钠摄取和模式, 表明该方法可能在早期动脉粥样硬化狭窄发展中具有更高的价值。.

62 RADIOLOGY AND NUCLEAR MEDICINE↗