WO2018052529A2

WO2018052529A2 - Synthesizing uranium chloride in molten salts

Info

Publication number: WO2018052529A2
Application number: PCT/US2017/043312
Authority: WO
Inventors: Michael Simpson; Andrew Mccall DODSON
Original assignee: Elysium Industries Ltd
Current assignee: Elysium Industries Ltd
Priority date: 2016-07-22
Filing date: 2017-07-21
Publication date: 2018-03-22
Anticipated expiration: 2019-01-22
Also published as: WO2018052529A3

Abstract

Systems and methods for forming UCI₃ are provided and can include heating a vessel containing liquid bismuth to a first temperature, mixing a uranium metal, a salt containing NaCI and BiCI₃ with the liquid bismuth, maintaining the vessel at the first temperature for a time sufficient to produce a molten NaCl-UCl₃ salt, heating the vessel to a second temperature so that the molten NaCl-UCl₃ solidifies, and removing the solid NaCl-UCl₃ from the vessel.

Description

SYNTHESIZING URANIUM CHLORIDE IN MOLTEN SALTS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/365,596, filed July 22, 2016, entitled "Synthesizing Uranium Chloride In Molten Salt," the entirety of which is incorporated by reference.

BACKGROUND

Field

[0002] Embodiments of the disclosure relate to synthesizing uranium chloride in molten salts.

[0003] The global demand for energy has largely been fed by fossil fuels. This typically involves taking reduced carbon out of the Earth and burning it. However, those hydrocarbons can be in limited supply and burning the hydrocarbons can produce carbon dioxide.

According to the U.S. Environmental Protection Agency, more than 9 trillion metric tons of carbon can be released into the atmosphere each year. Nuclear power can be appealing due to possibilities of abundant fuel and carbon-neutral energy production.

[0004] The predominant commercial nuclear reactor for electricity production can be the light water reactor (LWR). LWR's have significant drawbacks however. For example, they can use solid fuel with long radioactive half-lives and they can have relatively inefficient fuel utilization. As a result, LWR's can produce dangerous and long-lived waste products. The fuel can also be vulnerable to extreme accidents or proliferation of plutonium to make nuclear weapons.

[0005] To improve on LWR technologies, molten salt reactors (MSRs) have been researched since the 1950s. MSRs can be a class of nuclear fission reactors in which the primary coolant, or even the fuel itself, can be a molten salt mixture. In general, MSRs can provide energy more safely and cheaply than LWRs. As an example, MSRs can be low pressure and can be potentially less expensive and passively safer than LWRs. Furthermore, compared to LWRs, MSRs can provide lower per-kilowatt hour (kWh) levelized cost, comparatively benign fuel and waste inventory composition, and more efficient fuel utilization. [0006] Development of MSRs since the 1970s has taken a back seat, while the United States and other nations focused on the development of LWRs. However, as the world seeks more environmentally friendly, carbon-free energy, and as LWR maintenance and upgrade costs continue to rise, there has been renewed interest in MSRs.

SUMMARY

[0007] Embodiments of the present disclosure provide systems and methods for synthesizing a molten fuel salt including uranium chloride (UCI₃) in a vessel using temperatures below the operating temperatures of a molten salt reactor. NaCl-UCl₃ can be a valuable fuel salt or fuel salt constituent for fast-spectrum-molten-salt reactors because UCI₃ does not oxidize in the presence of U(0). Conversion of U(III) to U(IV) can be minimal in systems that can be controlled by the U(III)/U(0) redox couple, and this non-corrosive aspect can be desirable for extending the lifespan of reactor components, for example.

[0008] As discussed in greater detail below, using a simple configuration of a single vessel and a relatively low processing temperature, a UCI₃ fuel salt can be produced in a carrier salt (e.g., NaCl) in a scalable manner that can meet the commercial need and that minimizes the processing steps and the hazardous byproducts associated with the production process. As an example, a metallic actinide (e.g., uranium metal) can be dissolved in a liquid bismuth phase and reacted with a molten salt containing sodium chloride (NaCl) and bismuth chloride (B1CI₃). This results in the actinide being partitioned into the molten phase (e.g., NaCl-UCl₃). The NaCl-UCl₃ salt can be then cooled and solidified to form a solid salt that can be easily removable from the vessel. This solid salt can be used as a fuel salt for a molten chloride fast spectrum reactor, for example.

[0009] Other synthesis routes for production of UCI₃ have been previously developed. As an example, UCI₃ can be formed from reaction of uranium metal (U) with reactive chlorides or with UCI₂ gas. For example, U.S. Patent No. 7,217,402 discusses forming UCI₃ by reacting U metal with CdCl₂ to make UCI₃ in LiCl-KCl and Westphal, et al. discuss forming UCI₃ from the reaction of U metal with CuCi₂. (See, e.g., Westphal, B.R., Price, J.C., & Mariani, R.D., "Synthesis of Uranium Trichloride for the Pyrometallurgical Processing of Used Nuclear Fuel," November 2011 (INL/CON- 10-20111). However, embodiments of the present disclosure provide several benefits over this existing approach. • Liquid bismuth has a lower vapor pressure than cadmium, and can be thus compatible with the relatively high melting point of NaCl-UCl₃.

• By starting with B1CI₃ in the salt rather than forming it via reaction of the liquid metal with CI₂ gas, the process temperature can be kept relatively low. If NaCl were to be contacted with molten Bi with CI₂ bubbled into the bismuth, the process temperature would have to be greater than 800°C to maintain all of the fluids in the liquid phase.

• Starting with NaCl in contact with Cd metal would be even less feasible, because the cadmium would vaporize above 800°C.

• B1CI₃ can be commercially obtained, which makes working with chlorine gas

avoidable.

• The previously developed UCI₃ synthesis is not suitable for production at commercial scale.

[0010] Further advantages of embodiments of the disclosed systems and methods are as follows.

[0011] Scalability - The size of a reactor vessel used to form the NaCl-UCi₃ salt can be increased to accommodate an increase in materials. Alternatively, multiple reactor vessels can be used simultaneously.

[0012] Low Temperature - Synthesis operations can occur within a single vessel using liquid bismuth, allowing the reactions to occur without excessively high temperatures (e.g., below about 800°C). By avoiding these excessively high temperatures, the fuel salt can remain relatively stable and, therefore, less likely to corrode structural materials or to volatilize.

[0013] Simplified Workflow - The disclosed embodiments can produce solid NaCl-UCl₃ salt in one vessel. Therefore, manufacturing workflows can be simplified. For example, complicated pump systems can be omitted. Additionally, because liquid bismuth can remain within the vessel after the fuel salt is removed, the NaCl-UCl₃ salt can be produced without having to drain the system of bismuth. This allows the salt synthesis to be repeated without having to dispose of toxic byproducts or materials. [0014] Reduced Proliferation Risks -The NaCl-UCl₃ fuel salt can be shipped to reactor facilities, rather than enriched uranium. As a result, proliferation risks associated with shipping enriched uranium can be avoided.

[0015] In one embodiment, a method of forming uranium chloride UCI₃ is provided and can include heating a vessel containing liquid bismuth to a first temperature, mixing a uranium metal and a salt containing NaCl, and B1CI₃ with the liquid bismuth, maintaining the vessel at the first temperature for a time sufficient to produce a molten NaCl-UCl₃ salt, adjusting the temperature of the vessel to a second temperature sufficient to solidify the NaCl-UCl₃ salt, and removing the solid NaCl-UCl₃ from the vessel.

[0016] In an embodiment, removing the solid NaCl-UCl₃ from the vessel can include inserting one or more rods within the NaCl-UCl₃ salt when molten and removing the solid NaCl-UCl₃ from the vessel using the one or more rods. The one or more rods can be lowered into the molten NaCl-UCl₃ above the level of the liquid bismuth.

[0017] In an embodiment, the uranium metal can be mixed with the liquid bismuth prior to mixing the salt containing NaCl and the B1CI₃ with the liquid bismuth.

[0018] In an embodiment, the molten NaCl-UCl₃ can be immiscible with the liquid bismuth.

[0019] In an embodiment, the first temperature and the second temperature can each be below about 800°C. The second temperature can be below the freezing point of NaCl-UCl₃. As an example, the first temperature can be about 700°C. As a further example, the second temperature can be about 450°C.

[0020] In an embodiment, the NaCl-BiCl₃ salt can consist essentially of about 50 mol.

percent NaCl and about 50 mol. percent B1CI₃.

[0021] In an embodiment, the vessel can be held at the first temperature until the reaction of B1CI₃ with soluble uranium completes.

[0022] In an embodiment, the vessel can be at least partially formed from a molybdenum material.

[0023] In another embodiment, a system is provided and can include a fast spectrum chloride molten salt reactor and a fuel processing device. The molten salt reactor can include a reactor core having a line for transferring used fuel salt from and/or to the reactor core. The fuel processing device can include a vessel fluidically connected to the line and configured to hold liquid bismuth and receives the used fuel salt through the line from the reactor. The fuel processing device can also include a mixing element moveable into contact with the liquid bismuth and a heating element in thermal contact with the vessel. The fuel processing device can be configured to heat the vessel containing liquid bismuth to a first temperature, mix a uranium metal and a salt containing NaCl and B1CI₃ with the liquid bismuth, hold the vessel at the first temperature to produce a molten NaCl-UCl₃, adjust the temperature of the vessel to a second temperature so that the molten NaCl-UCl₃ solidifies, and remove the solid NaCl- UCI₃ from the vessel.

[0024] In an embodiment, the fuel processing device can further include one or more rods movable from a first position outside of the vessel to a second position within the vessel. The fuel processing device can be configured to insert the one or more rods into the molten NaCl- UCI₃ and remove the solid NaCl-UCl₃ from the vessel using the one or more rods.

[0025] In an embodiment, the uranium metal can be mixed with the liquid bismuth before mixing the NaCl and the B1CI₃ with the liquid bismuth.

[0026] In an embodiment, the NaCl-BiCl₃ salt can consist essentially of about 50 mol.

percent NaCl and about 50 mol. percent B1CI₃.

[0027] In an embodiment, the first temperature and the second temperature can each be below about 800°C. The second temperature can be below the freezing point of NaCl-UCl₃. As an example, the first temperature can be about 700°C. As a further example, the second temperature can be about 450°C.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] These and other features will be more readily understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0029] FIG. 1 schematically illustrates a nuclear thermal generator plant (NTGP) system.

[0030] FIG. 2 is a schematic illustration of an exemplary reactor suitable for use with the NTGP system of FIG. 1 [0031] FIG. 3 is a flow diagram illustrating an exemplary embodiment of a method for synthesizing a NaCl-UCl₃ fuel salt.

[0032] FIG. 4 is a schematic illustration of the method of FIG. 3.

[0033] It can be noted that the drawings can be not necessarily to scale. The drawings can be intended to depict only typical aspects of the subject matter disclosed herein, and therefore should not be considered as limiting the scope of the disclosure.

[0034] For a thorough understanding of the present disclosure, reference should be made to the following detailed description, including the appended claims, in connection with the above-described drawings. Although the present disclosure can be described in connection with exemplary embodiments, the disclosure can be not intended to be limited to the specific forms set forth herein. It can be understood that various omissions and substitutions of equivalents can be contemplated as circumstances can suggest or render expedient.

DETAILED DESCRIPTION

[0035] Embodiments of the present disclosure describe systems and methods for generating uranium chloride (also referred to as uranium trichloride or UCI₃) in a carrier salt (e.g., sodium chloride, NaCl) using a simple configuration of a single vessel and a relatively low processing temperature. As described herein, these systems and methods can be used in a fast-spectrum molten-salt reactor (FS-MSR). A FS-MSR, also sometimes referred to as a "fast neutron reactor" or simply a "fast reactor", can include nuclear reactors in which a fission chain reaction can be sustained by fast neutrons, as opposed to slow, or thermal, neutrons used in a thermal reactor.

[0036] The term "thermal" can refer to thermal equilibrium of the neutrons with media it interacts with inside the reactor (e.g., the reactor's fuel, moderator, structure, etc.), which can be much lower energy than the fast neutrons initially produced by fission. Thermal reactors can rely on a neutron moderator for reducing the speed of neutrons so as to make them capable of sustaining a nuclear chain reaction. The moderator can slow neutrons until they approach the average kinetic energy of the surrounding particles (i.e., reducing the speed of the neutrons to low-velocity thermal neutrons), thereby remaining uncharged and allowing them to penetrate deep in the target and close to the nuclei. [0037] FIG. 1 schematically illustrates a nuclear thermal generator plant (NTGP) system 100, which is a molten salt nuclear reactor configured to use NaCl-UCl₃ as a fuel salt or a fuel salt constituent to generate electrical energy from nuclear fission. The system 100 can include a reactor 200 having a reactor core 220 containing a fuel salt 104 (e.g., a fissile molten salt). Upon absorbing neutrons, nuclear fission can be initiated and sustained in the molten fuel salt 104 by chain-reaction in the fuel salt 104 within the reactor core 220, generating heat that elevates the temperature of the molten fuel salt 104 (e.g., to about 650°C or about 1,200°F). The heated the molten fuel salt 104 can be transported from the reactor core 220 to a primary heat exchange unit 106. The primary heat exchange unit 106 can be configured to transfer the heat generated by the nuclear fission from the molten fuel salt 104.

[0038] The primary heat exchange unit 106 can be provided in a variety of configurations. In various embodiments, the primary heat exchange unit 106 can be either internal or external to a reactor vessel (not shown) that contains the reactor core 220. In additional embodiments, the system 100 can be configured such that primary heat exchange (e.g., heat exchange from the molten fuel salt 104 to a different fluid) can occur both internally and externally to the reactor vessel. In other embodiments, the system 100 can be provided such that the functions of nuclear fission and primary heat exchange can be integral to the reactor core 220. That is, heat exchange fluids can be passed through the reactor core 220.

[0039] The transfer of heat from the molten fuel salt 104 can be realized in various ways. For example, the primary heat exchange unit 106 can include a pipe 108, through which the heated molten fuel salt 104 travels, and a secondary fluid 110 (e.g., a coolant salt) that surrounds the pipe 108 and absorbs heat from the molten fuel salt 104. Upon heat transfer, the temperature of the molten fuel salt 104 can be reduced in the primary heat exchange unit 106 and the molten fuel salt 104 can be transported from the primary heat exchange unit 106 back to the molten salt reactor core 102.

[0040] The system 100 can also include a secondary heat exchange unit 112 configured to transfer heat from the secondary fluid 110 to a tertiary fluid 114 (e.g., water). As shown in FIG. 1, the secondary fluid 110 can be circulated through secondary heat exchange unit 112 via a pipe 116.

[0041] Additionally or alternatively, in another embodiment (not shown), heat exchange can occur within the reactor core 220 prior to heat exchange within the secondary heat exchange unit 112. As an example, heat from the molten fuel salt 104 can pass to a solid moderator, then to a liquid coolant circulating through the reactor core 220. Subsequently, the liquid coolant circulating through the reactor core 220 can be transported to the secondary heat exchange unit 112. As required by basic thermodynamics, after one or more stages of exchange, heat can be finally delivered to an ultimate heat sink, e.g., the overall environment (not shown).

[0042] Heat received from the molten fuel salt 104 can be used to generate power (e.g., electric power) using any suitable technology. For example, when the tertiary fluid 114 in the secondary heat exchange unit 112 is water, it can be heated to a steam and transported to a turbine 118. The turbine 118 can be turned by the steam and drive an electrical generator 120 to produce electricity. Steam from the turbine 118 can be conditioned by an ancillary gear 122 (e.g., a compressor, a heat sink, a pre-cooler, and a recuperator) and it can be transported back to the secondary heat exchange unit 112.

[0043] Additionally, or alternatively, the heat received from the molten fuel salt 104 can be used in other applications such as nuclear propulsion (e.g., marine propulsion), desalination, domestic or industrial heating, hydrogen production, or combinations thereof.

[0044] In certain embodiments, the system 100 can also include an actively cooled freeze plug 126. The freeze plug 126 can be in fluid communication with the molten salt reactor core 102 and it can be configured to allow the molten fuel salt 104 to flow into a set of emergency dump tanks 130 in case of power failure and/or on active command.

[0045] While the system 100 is illustrated as having one primary heat exchanger 106, multiple heat exchangers can be used. FIG. 2 shows a cross section of the reactor 200 including heat exchangers 206. The reactor 200 can include an inner vessel wall 208, an outer vessel wall 210, a gamma shield 212, and a neutron absorber 216, which can be configured to confine fission products within the reactor 200. Within the reactor core 220, neutron reflectors 218 can be also positioned to elastically scatter neutrons. In some cases, a control rod 202 can be lowered into the reactor core 220 to help initiate nuclear fission.

[0046] During use, the pumps 204 can circulate the fuel salt 104 along paths generally indicated by arrows within the reactor core 220. For example, the fuel salt 104 can be pumped through the heat exchanger 206, along a path beside the neutron reflector 218, and through the channel 214 before returning to the heat exchanger 206.

[0047] During the operation of the reactor core 220, fission products can be generated in the molten fuel salt 104. The fission products can include a range of elements. The fission products can include, but are not limited to, rubidium (Rb), strontium (Sr), cesium (Cs), and barium (Ba), an element selected from lanthanides, palladium (Pd), ruthenium (Ru), silver (Ag), molybdenum (Mo), niobium (Nb), antimony (Sb), technetium (Tc), xenon (Xe), or krypton (Kr). The buildup of fission products (e.g., radioactive noble metals and radioactive noble gases) in the molten fuel salt 104 can impede or interfere with the nuclear fission in the reactor core 220 by poisoning the nuclear fission. For example, xenon- 135 and samarium- 149 can have a high neutron absorption capacity, and can lower the reactivity of the molten salt. Fission products can also reduce the useful lifetime of the reactor core 220 by clogging components, such as heat exchangers or piping.

[0048] Therefore, it can be desirable to keep concentrations of fission products in the molten fuel salt 104 below certain thresholds to maintain proper functioning of the molten salt reactor core 102. This goal can be accomplished by a chemical processing plant 205 configured to remove at least a portion of fission products generated in the molten fuel salt 104 during nuclear fission. During operation, molten fuel salt 104 can be transported from the reactor core 220 to the chemical processing plant 205, which can process the molten fuel salt 104 so that the molten salt reactor core 102 functions without loss of efficiency or degradation of components.

[0049] The chemical processing plant 205 can also produce an NaCl-UCl₃ fuel salt by synthesizing uranium chloride (UCI₃) in a carrier salt (e.g., NaCl). In certain embodiments, the produced NaCl-UCl₃ fuel salt can be returned to the reactor core 220.

[0050] A method 300 for producing the NaCl-UCl₃ fuel salt is schematically illustrated in the flow diagram of FIG. 3 with reference to the schematic illustrations in FIG. 4. In certain embodiment, the method 300 can be performed by the chemical processing plant 205. In other embodiments, the method can be performed 300 outside of the reactor 200. While the method 300 is discussed with reference to synthesis of UCI₃, actinide chlorides other than uranium (e.g., plutonium) can also be formed using embodiments of the method. [0051] In operations 302-304, a vessel containing liquid bismuth 402 is heated to a first temperature and uranium metal 404 is added to the liquid bismuth 402. In an embodiment, the first temperature can be about 700°C. At least a portion of the uranium metal 404 can dissolve within liquid bismuth to form a Bi-U solution 406. It may be understood that some of the uranium metal 404 can remain undissolved at the bottom of the liquid bismuth 402.

[0052] Embodiments of the uranium metal can adopt various forms. In one aspect, the uranium metal can be enriched uranium (e.g., low enriched uranium, LEU). In another aspect, the uranium can be depleted uranium. In another aspect, the uranium can be enriched from depleted uranium. In another aspect, the uranium can be naturally occurring uranium. In another aspect, the uranium can be obtained from a spent molten fuel salt.

[0053] In operation 306, a NaCl-BiCl₃ salt 408 can be added to the vessel and the Bi-U solution 406. In an embodiment, the NaCl-BiCl₃ salt 408 can consist essentially of NaCl and B1CI₃, with a concentration of about 50 mol. % NaCl and about 50 mol. % B1CI₃. In alternative embodiments, NaCl and B1CI₃ can be added separately to the vessel in amounts that achieve a concentration of about 50 mol. % NaCl and about 50 mol. % B1CI₃.

[0054] The first temperature is maintained in operation 310 while the NaCl-BiCl₃ salt 408 melts. As the Bi-U solution 406 is immiscible with the molten NaCl-BiCi₃ salt 408 and it has a higher density, the molten NaCl-BiCl₃ salt 408 can float above the Bi-U solution 406.

[0055] In operation 310, B1CI₃ can further react with soluble uranium and the metallic uranium can dissolve to replace it. After a sufficient amount of time elapses for the reaction to go to completion, the molten salt pool can include NaCl-UCl₃ molten salt 410 and the mass of the liquid bismuth pool can be largely depleted of uranium. In some cases, the reaction time can range from about 5 to about 10 hours to reach completion (i.e., the complete reaction of B1CI₃).

[0056] The reaction can be monitored using an electric potential measurement can be used to confirm that there can be still some residual U metal in the liquid bismuth. The electric potential difference between the liquid bismuth and a reference electrode can indicate whether U is present in the liquid bismuth.

[0057] In operations 312-316, the NaCl-UCl₃ salt 410 can be solidified and removed from the vessel. As an example, in operation 312, one or more solid rods can be inserted into the molten NaCl-UCl₃ salt 410. In some cases, the rods can be formed from a material that remains solid at temperatures employed by the method 300 (e.g., carbon steel, nickel, titanium, etc.).

[0058] In operation 314, the temperature can be lowered to a second temperature below the freezing point of the NaCl-UCl₃ molten salt 410 (e.g., below about 450°C). Subsequently, the NaCl-UCl₃ salt 410 can solidify and attach to the rods. The rods can be positioned above the level of the liquid bismuth 402 to facilitate removal of the NaCl-UCl₃ salt 410 in operation 316.

[0059] To repeat the method 300, the temperature of the vessel can be raised back to the first temperature (e.g., about 700°C), and additional metallic uranium can be added to the bismuth liquid remaining in the vessel. With each batch of NaCl-UCl₃ salt 410 synthesized, more bismuth metal can form and accumulate in the vessel. At some point, the Bi level will exceed a maximum amount suitable for the method 300 and Bi can be removed from the vessel (e.g., discarded or used to fabricate more B1CI₃).

[0060] Embodiments of the vessel can be configured to facilitate the method 300. In one aspect, the vessel can be formed of a material compatible with the synthesis without significant material degradation. Examples of such materials can include, but are not limited to, molybdenum, platinum, and palladium. In some cases, a housing of the vessel can be tapered, including a top end having slightly larger diameter than the bottom. For example, the ratio of the top diameter to the bottom diameter can be selected within the range from about 1.05 to about 1.2. This ratio can allow the solidified UCI₃ to be easily pulled out of the vessel without being stuck in place.

[0061] In another aspect, the vessel can include a coating layer (e.g., a platinum coating). This coating layer can be plated onto substrates such as titanium to provide corrosion resistance while also being suitable for periodic re-coating.

[0062] In a further aspect, the vessel can be sized to accommodate a desired UCI₃ production quantity (e.g., amount needed per day). In general, the devices and methods consistent with the disclosed embodiments can be readily scalable to accommodate a range of production needs. [0063] In an additional aspect (not shown), the vessel can further include a headspace with an inert cover gas to allow the solidified UCI₃ to be extracted while still in contact with the inert gas.

Example

[0064] An exemplary synthesis illustrating the method 300 for synthesizing a NaCl-UCl₃ fuel salt is discussed in detail below.

[0065] UCI₃ and of NaCl can be prepared within a 5 -liter capacity vessel made of high purity molybdenum. About 6.5 kg of uranium metal 404 can be added to about 10 kg of liquid bismuth 402 at a temperature of 700°C. The liquid bismuth 402 can be well stirred after addition of the U metal to form the Bi-U solution 406. To this can be added 9.3 kg of 50 mol. % NaCl/50 mol. % B1CI₃ salt 408.

[0066] As B1CI₃ reacts with the soluble uranium metal 404, undissolved uranium dissolves to replace it. After a sufficient amount of time for the reaction to go to completion, the molten salt pool contains about 8.55 kg of UCI₃ and about 1.45 kg of NaCl. The mass of the liquid bismuth 402, which has been largely depleted of U, can be about 15.2 kg. The volume of the liquid bismuth 402 can be about 1.5 liters. The volume of the molten salt pool containing the NaCl-UCl₃ salt can be about 2.7 liters. The total volume of the liquid can be 4.2 liters.

[0067] Subsequently, stainless steel metallic rods are inserted into the NaCl-UCl₃ fuel salt 410 above the level of the liquid bismuth 402. The temperature is lowered to the second temperature, 450°C, and the salt solidifies. Using the stainless steel rods, the solid NaCl- UCI₃ fuel salt can be withdrawn from the vessel.

[0068] To repeat the method 300, about 5 kg of bismuth can be removed from the vessel and the temperature can be raised back to 700°C. Additional uranium metal 404 can be added to the remaining liquid bismuth 402.

[0069] All references cited throughout this application, for example patent documents including issued or granted patents or equivalents, patent application publications, and non-patent literature documents or other source material, are hereby incorporated by reference herein in their entireties, as though individually incorporated by reference, to the extent each reference is at least partially not inconsistent with the disclosure in this application. For example, a reference that is partially inconsistent is incorporated by reference except for the partially inconsistent portion of the reference.

[0070] One of ordinary skill in the art will appreciate that starting materials, biological materials, reagents, synthetic methods, purification methods, analytical methods, assay methods, and biological methods other than those specifically exemplified can be employed in the practice of embodiments of the disclosure without resort to undue experimentation. All art-known functional equivalents, of any such materials and methods are intended to be included in the disclosed embodiments.

[0071] When a group of substituents is disclosed herein, it is understood that all individual members of that group and all subgroups, including any isomers, enantiomers, and diastereomers of the group members, are disclosed separately.

[0072] When a Markush group, or other grouping is used herein, all individual members of the group and all combinations and sub-combinations possible of the group are intended to be individually included in the disclosure.

[0073] When a compound is described herein such that a particular isomer, enantiomer, or diastereomer of the compound is not specified, for example, in a formula or in a chemical name, that description is intended to include each isomers and enantiomer of the compound described individual or in any combination. Additionally, unless otherwise specified, all isotopic variants of compounds disclosed herein are intended to be encompassed by the disclosure. For example, it will be understood that any one or more hydrogens in a molecule disclosed can be replaced with deuterium or tritium. Isotopic variants of a molecule are generally useful as standards in assays for the molecule and in chemical and biological research related to the molecule or its use. Methods for making such isotopic variants are known in the art. Specific names of compounds are intended to be exemplary, as it is known that one of ordinary skill in the art can name the same compounds differently.

[0074] As used herein, and in the appended claims, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to "a cell" includes a plurality of such cells and equivalents thereof known to those skilled in the art, and so forth. Additionally, the terms "a" (or "an"), "one or more" and "at least one" can be used interchangeably herein.

[0075] As used herein, the term "comprising" is synonymous with "including," "having," "containing," and "characterized by" and each can be used interchangeably. Each of these terms is further inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0076] As used herein, the term "consisting of excludes any element, step, or ingredient not specified in the claim element.

[0077] As used herein, the term "consisting essentially of does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim. In each instance herein any of the terms "comprising", "consisting essentially of," and "consisting of may be replaced with either of the other two terms.

[0078] The embodiments illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein.

[0079] The expression "of any of claims XX-YY" (where XX and YY refer to claim numbers) is intended to provide a multiple dependent claim in the alternative form and in some embodiments can be interchangeable with the expression "as in any one of claims XX-YY."

[0080] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which the disclosed embodiments belong.

[0081] Whenever a range is given in the specification, for example, a temperature range, a time range, a composition range, or a concentration range, all intermediate ranges and subranges, as well, as all individual values included in the ranges given, are intended to be included in the disclosure. As used herein, ranges specifically include the values provided as endpoint values of the range. For example, a range of 1 to 100 specifically includes the end point values of 1 and 100. It will be understood that any subranges or individual values in a range or sub-range that are included in the description herein can be excluded from the claims herein.

[0082] In the descriptions above and in the claims, phrases such as "at least one of or "one or more of may occur followed by a conjunctive list of elements or features. The term "and/or" may also occur in a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it is used, such a phrase is intended to mean any of the listed elements or features individually or any of the recited elements or features in combination with any of the other recited elements or features. For example, the phrases "at least one of A and Β;" "one or more of A and Β;" and "A and/or B" are each intended to mean "A alone, B alone, or A and B together." A similar interpretation is also intended for lists including three or more items. For example, the phrases "at least one of A, B, and C;" "one or more of A, B, and C;" and "A, B, and/or C" are each intended to mean "A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together." In addition, use of the term "based on," above and in the claims is intended to mean, "based at least in part on," such that an unrecited feature or element is also permissible.

[0083] The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed embodiments. Thus, it should be understood that although the present application may include discussion of preferred embodiments, exemplary embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art. Such modifications and variations are considered to be within the scope of the disclosed embodiments, as defined by the appended claims. The specific embodiments provided herein are examples of useful embodiments of the present disclosure and it will be apparent to one skilled in the art that they may be carried out using a large number of variations of the devices, device components, and methods steps set forth in the present description. As will be obvious to one of skill in the art, methods and devices useful for the present methods can include a large number of optional compositions and processing elements and steps.

Claims

What is claimed is:

1. A method of forming uranium trichloride (UCI₃) in a molten salt, the method comprising:

heating a vessel containing liquid bismuth to a first temperature;

mixing a uranium metal and a salt containing NaCl and B1CI₃ with the liquid bismuth; maintaining the vessel at the first temperature for a time sufficient to produce a molten NaCl-UCl₃ salt;

adjusting the temperature of the vessel to a second temperature sufficient to solidify the NaCl-UCl₃ salt; and

removing the solid NaCl-UCl₃ from the vessel.

2. The method of claim 1, wherein removing the solid NaCl-UCl₃ from the vessel comprises inserting one or more rods within the NaCl-UCl₃ salt when molten and removing the solid NaCl-UCl₃ from the vessel using the one or more rods.

3. The method of claim 2, wherein the one or more rods are lowered into the molten NaCl-UCl₃ above the level of the liquid bismuth.

4. The method of claim 1, wherein the uranium metal is mixed with the liquid bismuth prior to mixing the salt containing NaCl and the B1CI₃ with the liquid bismuth.

5. The method of claim 1, wherein the molten NaCl-UCl₃ is immiscible with the liquid bismuth.

6. The method of claim 1, wherein the first temperature and the second temperature are each below about 800°C.

7. The method of claim 1, wherein the first temperature is about 700°C.

8. The method of claim 1, wherein the second temperature is below the freezing point of NaCl-UCl₃.

9. The method of claim 1, wherein the second temperature is about 450°C.

10. The method of claim 1, wherein the NaCl-BiCl₃ salt consists essentially of about 50 mol. percent NaCl and about 50 mol. percent B1CI₃.

11. The method of claim 1, wherein the vessel is held at the first temperature until the reaction of B1CI₃ with soluble uranium completes.

12. The method of claim 1, wherein the vessel is at least partially formed from a molybdenum material.

13. A system comprising:

a fast spectrum chloride molten salt reactor having a reactor core including a line for transferring used fuel salt from the reactor core;

a fuel processing device comprising:

a vessel fluidically connected to the line, the vessel configured to holding liquid bismuth and receiving the used fuel salt through the line;

a mixing element moveable into contact with the liquid bismuth; and a heating element in thermal contact with the vessel;

wherein the fuel processing device is configured to:

heat the vessel containing liquid bismuth to a first temperature; mix a uranium metal, a salt containing NaCl, and B1CI₃ with the liquid bismuth;

hold the vessel at the first temperature to produce a molten NaCl-UCl₃; adjust the temperature of the vessel to a second temperature so that the molten NaCl-UCl₃ solidifies; and

remove the solid NaCl-UCl₃ from the vessel.

14. The system of claim 13, wherein the fuel processing device further includes one or more rods movable from a first position outside of the vessel to a second position within the vessel.

15. The system of claim 14, wherein the fuel processing device is configured to insert the one or more rods into the molten NaCl-UCl₃ and remove the solid NaCl-UCl₃ from the vessel using the one or more rods.

16. The system of claim 13, wherein the uranium metal is mixed with the liquid bismuth before mixing the NaCl and the B1CI₃ with the liquid bismuth.

17. The system of claim 13, wherein the NaCl-BiCi₃ salt consists essentially of about 50 mol. percent NaCl and about 50 mol. percent B1CI₃.

18. The system of claim 13, wherein the first temperature and the second temperature are each below about 800°C.

19. The system of claim 16, wherein the first temperature is about 700°C.

20. The system of claim 13, wherein the second temperature is below the freezing point of NaCl-UCl₃.

21. The method of claim 18, wherein the second temperature is about 450°C.