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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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Reversible Room-Temperature Fluoride-Ion Insertion in a Tunnel-Structured Transition Metal Oxide Host
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Stable lithium fluoride-based cathodes for metal and metal-ion batteries
A battery electrode composition is provided that comprises composite particles. Each composite particle may comprise, for example, active lithium fluoride/metal nanocomposite material optionally embedded into a nanoporous, electrically-conductive skeleton matrix material particle(s), where each of these composite particles is further encased in a Li-ion permeable, chemically and mechanically robust, protective outer shell that is impermeable to electrolyte solvent molecules. The active lithium fluoride/metal nanocomposite material is provided to store and release Li ions during battery operation.
Characterization of structural heterogeneity in carbon fluorides.
Abstract not provided.
Atomic layer deposition of fluoride thin films
A secondary electron emissive coating. The coating is formed by atomic layer deposition of CaF 2 on a substrate by ALD half cycle exposure of an alkaline metal amidinate and ALD half cycle exposure of a fluorinated compound, where the deposition occurs at a reaction temperature greater than a highest sublimation temperature of the first metal precursor and the second metal precursor and less than 50° C. above the highest sublimation temperature.
Thermal Hydraulic Modeling of the Kairos Power Generic Fluoride High Temperature Reactor in MELCOR
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Initial Development of a Generic Fluoride Salt-Cooled Reactor Model
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MELCOR Accident Progression and Source Term Analysis for a Fluoride High-Temperature Reactor.
Abstract not provided.
Assessing Stainless Steel Compatibility in Flowing Fluoride Salts
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MELCOR for High Temperature Gas-Cooled and Fluoride High Temperature Reactor Modeling.
Abstract not provided.
MELCOR for High Temperature Gas-Cooled and Fluoride High Temperature Reactor Modeling.
Abstract not provided.
Methodology for Assessing Stainless Steel Compatibility in Fluoride Salts at 550°-850°C
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Lithium yttrium ytterbium fluoride nanocrystals for laser cooling applications
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Investigation of Misuse Potential and Detection for Homogeneous Fluoride Fast Molten Salt Reactors Based on Neutronics Signatures
The International Atomic Energy Agency (IAEA) has obligations to apply safeguards to nuclear material and facilities within States subject to IAEA safeguards agreements. As a result of these obligations, safeguards will need to be applied to Generation IV reactors, including liquid fueled molten salt reactors (MSRs), if they are deployed in States with safeguards agreements. Recently, the IAEA has noted that a growing number of Member States are showing interest in MSR technology. This has been accompanied by an increase in short term development and deployment activities relating to MSRs. To ensure MSRs can be safeguarded effectively and efficiently upon possible future deployment, safeguards approaches and techniques need to be investigated now.
A laboratory-scale process for producing dilithium beryllium tetrafluoride (FLiBe) with dissolved uranium tetrafluoride
Flibe Energy, Incorporated (FEI)'s conceptual Lithium Fluoride Thorium Reactor (LFTR) incorporates a chemical processing facility aimed at recovering uranium and other valuable volatile radionuclides while managing harmful radionuclides from the used fuel. The fuel utilized in this reactor is a combination of dilithium beryllium tetrafluoride (Li 2 BeF 4 or FLiBe) and uranium tetrafluoride (UF 4 ), (FLiBe/U). FEI's plan involves extracting the uranium and other valuable volatile fluoride-forming radionuclides using nitrogen trifluoride (NF 3 ). To facilitate laboratory-scale testing of uranium extraction using NF 3 and address the toxicity and physical hazards associated with beryllium and beryllium fluoride (BeF 2 ), we used a two-step process to prepare the simulated fuel salt. The first step entailed thermally decomposing ammonium beryllium tetrafluoride [(NH 4 ) 2 BeF 4 ] (ABeF) through a nominal 3-step process, combined with appropriate amounts of lithium fluoride (LiF) and UF 4 , resulting in the formation of beryllium fluoride (BeF 2 ). In the second step, the mixture was repeatedly melted and frozen at the melting point of FLiBe to prepare the eutectic FLiBe with dissolved UF 4 . Although the concept appears straightforward, the production of FLiBe/U involved various challenges. These challenges included transporting the gaseous decomposition products of ABeF, hydrogen fluoride (HF) and ammonia (NH 3 ), while preventing the formation of ammonium fluoride (NH 4 F). Additionally, it was necessary to control the reaction between the higher-than-anticipated water content in the commercial ABeF with NH 3 , HF, and the condensed NH 4 F, protect UF 4 from forming an unknown black compound, select suitable structural materials to mitigate fluoride corrosion, address the risks associated with beryllium toxicity through equipment design and operational protocols, and monitor process conditions. This article provides an account of the thermal decomposition chemistry observed in the commercial ABeF, describes the FLiBe/U production apparatus, describes the experiences and process refinements developed to prepare FLiBe/U, and presents our characterizations of prepared FLiBe/U.
Sulfur Hexafluoride Treatment of Used Nuclear Fuel to Enhance Separations
Reactive Gas Recycling (RGR) technology development has been initiated at Savannah River National Laboratory (SRNL), with a stretch-goal to develop a fully dry recycling technology for Used Nuclear Fuel (UNF). This approach is attractive due to the potential of targeted gas-phase treatment steps to reduce footprint and secondary waste volumes associated with separations relying primarily on traditional technologies, so long as the fluorinators employed in the reaction are recycled for use in the reactors or are optimized for conversion of fluorinator reactant. The developed fluorination via SF 6 , similar to the case for other fluorinators such as NF 3 , can be used to address multiple fuel forms and downstream cycles including continued processing for LWR via fluorination or incorporation into a aqueous process (e.g. modified FLUOREX) or for subsequent pyro treatment to be used in advanced gas reactor designs such metal- or gas-cooled reactors. This report details the most recent experimental results on the reaction of SF 6 with various fission product surrogate materials in the form of oxides and metals, including uranium oxides using a high-temperature DTA apparatus capable of temperatures in excess of 1000°C. The experimental results indicate that the majority of the fission products form stable solid fluorides and sulfides, while a subset of the fission products form volatile fluorides such as molybdenum fluoride and niobium fluoride, as predicted thermodynamically. Additional kinetic analysis has been performed on additional fission products. A key result is the verification that SF 6 requires high temperatures for direct fluorination and subsequent volatilization of uranium oxides to UF 6 , and thus is well positioned as a head-end treatment for other separations technologies, such as the volatilization of uranium oxide by NF 3 as reported by colleagues at PNNL, advanced pyrochemical separations or traditional full recycle approaches. Based on current results of the research at SRNL on SF 6 fluoride volatility for UNF separations, SF 6 treatment renders all anticipated volatile fluorides studied to be volatile, and all non-volatile fluorides studied to be non-volatile, with the notable exception of uranium oxides. This offers an excellent opportunity to use this as a head-end separations treatment process because: 1. SF 6 can be used to remove volatile fluorides from a UNF matrix while leaving behind uranium oxides. Therefore an agent such as NF 3 should be able to very cleanly separate a pure UF 6 stream, leaving compounds in the bottoms such as PuF 4 , SrF 2 and CsF after the UNF matrix has been pre-treated with SF 6 . 2. Due to the fact that the uranium oxide is not separated in the volatilization step upon direct contact with SF 6 at moderately high temperatures (≤ 1000°C), this fluoride approach may be well-suited for head-end processing for Gen IV reactor designs where the LWR is treated as a fuel stock, and it is not desired to separate the uranium from plutonium, but it is desired to separate many of the volatile fission products. 3. It is likely that removal of the volatile fission products from the uranium oxide should simplify both traditional and next generation pyroprocessing techniques. 4. SF 6 treatment to remove volatile fission products, with or without treatment with additional fluorinators, could be used to simplify the separations of traditional aqueous processes in similar fashion to the FLUOREX process. Further research should be conducted to determine the separations efficiency of a combined SF 6 /NF 3 separations approach which could be used as a stand-alone separations technology or a head-end process.
Elemental Fluorine-18 Gas: Enhanced Production and Availability
The overall objective of this project was to develop an efficient, reproducible and reliable process for the preparation of fluorine-18 labeled fluorine gas ([¹⁸F]F₂) from readily available cyclotron-produced [¹⁸F]fluoride ion. The two step process entailed the production of [¹⁸F]fluoromethane with subsequent conversion to [¹⁸F]F₂ by electric discharge of [¹⁸F]fluoromethane in the presence of carrier nonradioactive F₂ gas. The specific goals of this project were i) to optimize the preparation of [¹⁸F]fluoromethane from [¹⁸F]fluoride ion; ii) to develop a prototype automated system for the production of [¹⁸F]F₂ from [¹⁸F]fluoride ion and iii) develop a compact user friendly automated system for the preparation of [¹⁸F]F₂ with initial synthesis of fluorine-18 labeled radiotracers. Over the last decade there has been an increased interest in the production of "non-standard" positron-emitting isotopes for the preparation of new radiotracers for a variety of applications including medical imaging and therapy. The increased availability of these isotopes from small biomedical cyclotrons has prompted their use in labeling radiotracers. In much the same way the production of [¹⁸F]F₂ gas has been known for several decades. However, access to [¹⁸F]F₂ gas has been limited to those laboratories with the means (e.g. F₂ targetry for the cyclotron) and the project-based need to work with [¹⁸F]F₂ gas. Relatively few laboratories, compared to those that produce [¹⁸F]fluoride ion on a daily basis, possess the capability to produce and use [¹⁸F]F₂ gas. A simplified, reliable system employing [¹⁸F]fluoride ion from cyclotron targetry systems that are already in place coupled with on-demand production of the [¹⁸F]F₂ gas would greatly enhance its availability. This would improve the availability of [¹⁸F]F₂ gas and promote further work with a valuable precursor. The major goals of the project were accomplished over the funding period. The preparation of ¹⁸F]fluoromethane has been automated with reproducible yields greater than 90% conversion from [¹⁸F]fluoride ion. A trap and release system was established for the [¹⁸F]fluoride ion concentration and direct elution of the [¹⁸F]fluoride ion into the reaction vial with the appropriate base and precursor in DMSO. Other solvents were also investigated. The production time for [¹⁸F]fluoromethane is less than 10 minutes. An automated system for the [¹⁸F]F₂ gas production from the [18F]fluoromethane has been developed. The unit coupled to the [¹⁸F]fluoromethane system permits the on demand production of [¹⁸F]F₂ gas. In less than 30 minutes, mCi quantities of [¹⁸F]F₂ gas were produced. Several variables for the [¹⁸F]F₂ gas production were investigated and a set of parameters for reproducible operation were determined. These parameters included discharge chamber size, carrier gas (He, Ne, Ar), discharge time, discharge current, mass of F₂ gas added to the chamber. FDOPA and EF5 were used to test the reactivity of the [¹⁸F]F₂ gas. Both products were produced in low to modest yield. The ready availability of [¹⁸F]F₂ gas has potential impact to advance both DOE mission-driven initiatives and nuclear medicine initiatives through other federally funded agencies such as NIH and DoD. New reactions involving the use of [¹⁸F]F₂ gas will lead to direct labeling of new radiotracers and intermediates as well as new fluorine-18 labeled synthons that may be further reacted with other reagents to provide useful fluorine-18 labeled compounds. New tracers to understand and follow plant and microbial metabolism as well as new tracers for nuclear medicine applications, that have been either difficult to obtain or never produced due to the limited availability of [¹⁸F]F₂ gas, may be prepared using the techniques developed .