Chloride based volatility for the recovery of uranium from used nuclear fuel

Abstract

Disclosed herein are methods and systems for the recovery of uranium from used nuclear fuel using nonaqueous chemistry without electrometallurgy techniques, such as pyroprocessing. The methods and systems use chloride-based volatility (CBV) as the basis for uranium recovery from the used nuclear fuel. The solid used nuclear fuel containing solid uranium oxide is maintained under UCl4 sublimating conditions in a chlorinating environment for a period of time sufficient to convert at least some solid uranium oxide into UCl4 in a gas phase.

Description

CHLORIDE BASED VOLATILITY FOR THE RECOVERY OF URANIUM FROM USED NUCLEAR FUELCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 606,449, filed December 5, 2023, which is incorporated by reference herein in its entirety.STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] The new inventions in this application were made with government support under the ARPA-E ONWARDS program Award No. DE-AR0001612. The government has certain rights in these inventions.INTRODUCTION

[0003] In all operating or proposed commercial nuclear reactors, the majority of the spent or used nuclear fuel (UNF) is composed of uranium. Recovery / reuse of this uranium, enabled by a reduced-cost approach with favorable non-proliferation and safeguards characteristics, could reduce requirements for permanent disposal and be of great interest for the nuclear industry.

[0004] The majority of current and future planned nuclear reactors in the United States use a mixture of uranium isotopes, specifically238U and235U, in the form of uranium dioxide, UO2. Though uranium remains the primary component (>90%), the buildup of fission products, plutonium and other minor actinides, rare earths, transition metals, and main group elements prevent the fuel from being used further.

[0005] Chemical treatment of used nuclear is typically performed in two media, aqueous solutions (UREX / PUREX) and molten salt (pyroprocessing). Both methods are well understood, with decades of development. Aqueous processing is performed commercially in other areas of the world, specifically France. Aqueous processes tend to generate large volumes of liquid waste and tend to occupy large footprints. Pyroprocessing (practiced at several of the United States National Laboratories) is a collection of electrochemical treatments in molten salts for oxide, halide, and metallic fuel. Pyroprocessing is a low throughput operation that occupies a small facility footprint, compared to aqueous processing, but tends to involve more hands-on operations. Pyroprocessing is not performed commercially.

[0006] In all operating or proposed commercial nuclear reactors, the majority of the spent or used nuclear fuel (UNF) is composed of uranium. Recovery / reuse of this uranium, enabled by a reduced-cost approach with favorable non-proliferation and safeguards characteristics, could reduce requirements for permanent disposal and be of great interest for the nuclear industry.CHLORIDE BASED VOLATILITY FOR THE RECOVERY OF URANIUM FROM USED NUCLEAR FUEL

[0007] A novel approach is proposed herein for the selective removal of uranium from UNF by exploiting the unique physical properties of uranium tetrachloride (UCk), relative to fission products and other materials present in UNF.

[0008] Disclosed herein are methods and systems for the recovery of uranium from used nuclear fuel using nonaqueous chemistry without electrometallurgy techniques. The methods and systems described herein use chloride-based volatility (CBV) as the basis for uranium recovery from the used nuclear fuel. The solid used nuclear fuel containing solid uranium oxide is maintained under UCI4 sublimating conditions in a chlorinating environment for a period of time sufficient to convert at least some solid uranium oxide into UCI4 in a gas phase.

[0009] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.BRIEF DESCRIPTION OF DRAWINGS

[0010] Various aspects of at least one example are discussed below with reference to the accompanying figures, which are not intended to be drawn to scale. The figures are included to provide an illustration and a further understanding of the various aspects and examples, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of a particular example. The figures, together with the remainder of the specification, serve to explain principles and operations of the described and claimed aspects and examples. In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every figure.

[0011] FIG. 1 illustrates a simple embodiment of a method for the chloride-based volatility (CBV) separation of uranium from UNF.

[0012] FIG. 2 illustrates a flow diagram for the CBV of uranium from UNF.

[0013] FIG. 3 illustrates an embodiment of a larger waste handling process showing how the CBV method of FIG. 1 can be incorporated into a UNF handling and disposal system.

[0014] FIG. 4 illustrates another embodiment of a larger waste handling process showing how the CBV method of FIG. 1 can be incorporated into a UNF handling and disposal system.

[0015] FIG. 5 illustrates the experimental apparatus used for separating uranium from a surrogate UNF material.

[0016] FIG. 6A illustrate an upstream portion of an experimental apparatus used to generate the experimental data.

[0017] FIG. 6B illustrates a single-zone furnace portion of an experimental apparatus used to generate the experimental data.

[0018] FIG. 6C illustrates a downstream portion of an experimental apparatus used to generate the experimental data.

[0019] FIG. 7 illustrates a multi-zone furnace portion of an experimental apparatus used to generate the experimental data.

[0020] FIG. 8 illustrates a schematic of a working tube including quartz wool, according to an example experiment.

[0021] FIG. 9A illustrates an example baffle used in the generation of some experimental data.

[0022] FIG. 9B illustrates a schematic of a working tube including a baffle, according to an example experiment.DETAILED DESCRIPTION

[0023] Before the uranium removal systems and methods are disclosed and described, it is to be understood that this disclosure is not limited to the particular structures, process steps, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments of the uranium removal systems and methods onlyand is not intended to be limiting. It must be noted that, as used in this specification, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a lithium hydroxide" is not to be taken as quantitatively or source limiting, reference to "a step" may include multiple steps, reference to "producing" or "products" of a reaction should not be taken to be all of the products of a reaction, and reference to "reacting" may include reference to one or more of such reaction steps. As such, the step of reacting can include multiple or repeated reaction of similar materials to produce identified reaction products.

[0024] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as those commonly understood to one of ordinary skill in the art to which this technology pertains.

[0025] For the purposes of this application the following terms shall have the following meanings:

[0026] Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein should be understood as modified in all instances by the term “about.” The term “about” when used herein in connection with numerical values means ± 20% and with percentages means ±4%. Note that all percentages (%) are by weight unless otherwise specified.

[0027] As used herein, the term “comprising” refers to a composition, compound, formulation, or method that is inclusive and does not exclude additional elements or method steps.

[0028] As used herein, the term “consisting of’ refers to a compound, composition, formulation, or method that excludes the presence of any additional component or method steps.

[0029] As used herein, the term “consisting essentially of’ refers to a composition, compound, formulation or method that is inclusive of additional elements or method steps that do not materially affect the characteristic(s) of the composition, compound, formulation or method.

[0030] In all operating or proposed commercial nuclear reactors, the majority of the spent or used nuclear fuel (UNF) is composed of uranium. Recovery / reuse of this uranium, enabled by a reduced-cost approach with favorable non-proliferation and safeguards characteristics, could reduce requirements for permanent disposal and be of great interest for the nuclear industry.

[0031] Ideally, the bulk uranium would be separated from the fission products, without greatly increasing the volume, as is characteristic of the methods mentioned above. Primary factors hindering such a process include: a) the chemical similarity of uranium and plutonium, b) the potential for nuclear proliferation if the plutonium is purified from the UNF as a specific process step, and c) the intense radiation from minor actinides. To address these issues, a novel approach is proposed herein for the selective removal of uranium from UNF by exploiting the unique physical properties of uranium tetrachloride (UCI4), relative to fission products and other materials present in UNF.

[0032] This disclosure presents a method for the recovery of uranium from used fuel using nonaqueous chemistry without electrometallurgy techniques, such as pyroprocessing. The methods and systems use chloride-based volatility (CBV) as the basis for uranium recovery from UNF. Due to the low volatility of trivalent f-element chlorides, e.g., plutonium, lanthanide and other fission products (FPs), a separation occurs based on the temperature at which the fission products (e.g., uranium (IV) chloride (UCI4)) become volatile chlorides. Thus, a CBV method may be uniquely suited for uranium separation from UNF. Note that the CBV separation process is described below in terms of separating uranium from UNFs containing uranium oxide. However, the CBV process is equally applicable to uranium metal and the processing UNFs containing uranium metal. The CBV process could also be adapted to the processing of UNFs containing uranium chloride molten salts. Thus, while presented in the terms of processing uranium oxide UNFs, the reader should understand that the process equally may be applied to any uranium containing material, generally, regardless of the form of the uranium (e.g., oxide, metal, halide, etc.) and regardless of whether the uranium is UNF.

[0033] Although not related to used fuel, attempts have also been made to generate uranium chloride from uranium oxide. However, conversion, especially at scale, is complicated because, while the exposed surface of the oxide could be converted to uranium tetrachloride, the resulting chloride may form an in-situ shell or “cap” around the remaining oxide material which prevents any further chlorination.

[0034] However, metal chlorides have a wide range of sublimation and boiling points that can be used to create a simple, temperature-based separation. The proposed method of separation uses sublimation and is potentially applicable to common uranium fuels with specific process modifications based on the fuel type. The relatively low sublimation range for UCI4, 500°C - 650°C, which is not within 50°C of any known oranticipated FPs, illustrates the potential to isolate the bulk uranium from UNF, see Table 1 for a list of selected FPs along with their boiling or sublimation points. The chlorination environment coupled with the thermodynamic instability of Pu(IV) will drive plutonium to the trivalent ion as PuCh, which has a significantly higher boiling point of 1767°C, well beyond the parameters of the process. The high boiling point of PuCh is in line with other FPs such as241Am, all of the rare earth, alkaline earth, and alkali elements, leaving a complex mixture behind. This residual mixture will produce significant radiologic activity due to the241Am isotope, preventing opportunities for proliferation. Further, several main group and transition metal FPs boil significantly below UCI4, allowing for an additional separation.

[0035] Table 1. Boiling or Sublimation Temperature for Selected Metal Chlorides at latm

[0036] FIG. 1 illustrates a simple embodiment of a method 100 for the CBV separation of uranium from UNF. In the method 100 as shown, the UNF containing the uranium oxide (e.g., UO2 or UaOs) is transported, prepared, and placed in a chlorination chamber in a preparation operation 102. In an embodiment, transportation may include removing the UNF from a reactor or storage facility. The preparation operation 102 may also include pulverization or crushing and voloxidation of solid UNF into a powder or other aggregate form to assist in the contacting of the uranium oxide in the UNF.

[0037] A chlorination and UCI4 sublimation operation 104 is then performed. In this operation 104, the CBV separation method maintains the UNF under UCI4 sublimating conditions in a chlorinating environment. By maintaining the solid UNF under UCI4 sublimating conditions, as the chlorinating environment causes the molecules of UO2 to react to become UCI4, the UCI4 will sublimate, i.e., go directly from a solid form to a gaseous form. This phase change from solid to gas prevents the UCI4 from forming acap on the surface of the solid UNF and thereby preventing the further chlorination of the UNF.

[0038] In embodiments, the UNF material subjected to the chlorination and UCI4 sublimation operation 104 is at least 50% by weight uranium oxide, and can be at least 75% uranium oxide, at least 80% uranium oxide, at least 90% uranium oxide find even at least 95% uranium oxide. The remaining non-uranium oxide material in the UNF can be considered impurities and include the other materials such as FPs and cladding materials as described above. These impurities may be up to 50% by weight of the UNF such as UNF containing at least 0.1%, at least 0.5%, at least 1.0%, at least 5%, at least 10% and at least 25% by weight impurities.

[0039] A chlorinating environment refers to conditions in which the UNF is exposed to Cl. In an example, a chlorinating environment is Ar gas (or another noble gas, in examples) containing at least some carbon tetrachloride (CCI4) so that maintaining the UNF in a chlorinating environment could include placing the UNF, for example as a powdered solid material, in a chamber filled with Ar and CCI4. In an example, a chlorinating environment is Ar gas (or another noble or intert gas, in examples) containing at least some hydrogen chloride (HC1) so that maintaining the UNF in a chlorinating environment could include placing the UNF, for example as a powdered solid material, in a chamber filled with Ar and HC1. Specific examples described herein, including referring to the Figures, may describe an Ar / CC14 chlorinating environment as a particular example for conciseness; however, the technology may also utilize / include other appropriate chlorinating environments (e.g. including other appropriate Cl-containing compounds and / or other noble / inert gasses) in accordance with the disclosures herein.

[0040] UCI4 sublimating conditions in a chlorinating environment refers to pressure and temperature combinations in which UCI4 will sublimate. The actual pressures and temperatures that result in UCI4 sublimating conditions could also vary depending on the chlorinating environment used. Agitation or mixing may also be performed during the chlorination operation and UCI4 sublimation operation 104 to improve kinetics of the chlorination reaction.

[0041] For an example Ar / CCU chlorinating environment and at pressures of about 1 atm, UCI4 sublimates within a temperature range of 500°C-650°C. Specifically, the sublimating conditions in an Ar / CCU environment at a pressure of from 0.1 atm to 10atm are a temperature from 450°C-700°C. More narrowly, sublimating conditions may be a pressure of from 0.9 atm to 1.5 atm and a temperature from 500°C-650°C in an Ar / CCh environment. It is believed a significantly increased pressure would increase the temperatures needed to volatilize the UC14. Similarly, operating at a reduced pressure, i.e., pulling a slight vacuum to decrease the pressure within the chamber to less than 1 atm will reduce the temperature needed to volatilize the materials.

[0042] The chlorination and UCI4 sublimation operation 104 may be performed until all or substantially of the solid uranium from the original UNF has been sublimated as UCI4. The reduction in mass of the UNF or other parameters may be monitored in real time to determine when to terminate the chlorination. In an embodiment, the chlorination and UCI4 sublimation operation 104 may be performed for a fixed period of time or as necessary to convert 20%, 50%, 90%, 95%, 99% or even 99.9% of the uranium into UCI4.

[0043] In the chlorination chamber, after sublimation an Ar, CCI4, and UCI4 gas mixture is created as the product of the chlorination and UCI4 sublimation operation 104. In the embodiment shown in FIG. 1, after the UCI4 has sublimated into the gas phase, the Ar, CCI4, and UCI4 gas mixture is separated from the remaining UNF material, such as by being transferred to a collection chamber, in a gas removal operation 106.

[0044] After the gas removal operation 106, the conditions (e.g., pressure, temperature) of the UC14-containing gas may be modified to cause the deposition of the UCI4 from the gas phase, yielding a solid (or liquid, depending on the conditions) UCI4 material that is then collected in a collection operation 108.

[0045] FIG. 2 illustrates an embodiment of a CBV separation system 200 based on the method described in FIG. 1. In the embodiment shown, prepared UNF is placed in the chlorination chamber 204. An Ar or other inert gas mixture is then sparged through a pool of (in some examples, warm) CCI4202 in order to create a CC14-containing gas (chlorination gas). The chlorination chamber 204 is then filled with the CCI4- containing gas to provide the chlorinating environment. In addition, the pressure and temperature of the chlorination chamber 204 are controlled to maintain the UNF under UCI4 sublimating conditions. Over time, solid uranium oxide will react with the Cl of the CCk to create gaseous UCI4 and CO2. The sublimation of the UCI4 will then create a combined gas mixture that will include the Ar, any residual unreacted CCI4, thenewly-generated UC14 and CO2, and any other constituents from the UNF that volatilize off under these conditions.

[0046] In some examples, pressures within chlorination chamber 204 may be between about 0.1 atm and about 10 atm. In some examples, pressures within chlorination chamber 204 may be between about 0.9 atm and about 1.5 atm. In some examples, pressures within chlorination chamber 204 may be about 1 atm.

[0047] In some examples, temperatures within chlorination chamber 204 may be between about 400°C and about 750°C. In some examples, temperatures within chlorination chamber 204 may be between about 450°C and about 700°C. In some examples, temperatures within chlorination chamber 204 may be between about 500°C and about 700°C. In some examples, temperatures within chlorination chamber 204 may be between about 500°C and about 650°C. In some examples, temperatures within chlorination chamber 204 may be between about 500°C and about 600°C. In some examples, temperatures within chlorination chamber 204 may be between about 550°C and about 600°C. In some examples, temperatures within chlorination chamber 204 may be between about 550°C and about 575°C. In some examples, temperatures within chlorination chamber 204 may be between about 500°C and about 600°C. In some examples, temperatures within chlorination chamber 204 may be between about 575°C and about 650°C. In some examples, temperatures within chlorination chamber 204 may be about 500°C. In some examples, temperatures within chlorination chamber 204 may be about 600°C. In some examples, temperatures within chlorination chamber 204 may be about 550°C. In some examples, temperatures within chlorination chamber 204 may be about 575°C.

[0048] In some examples, agitation or mixing may be performed during the chlorination to improve the kinetics of the chlorination operation. In this case, the chlorination chamber 204 may be provided with mixing paddles, injectors for gas injection, or any other component for providing agitation to the UNF in the chlorination chamber 204.

[0049] The UC14-containing gas mixture is then transferred from the chlorination chamber 204 to a UCI4 collection chamber 206. It should be noted that this gas mixture will be referred to as the UCU-containing gas mixture for the sake of convenience even though the mixture may be much more complex; in reality, UNF can encompass a wide variety of materials include FPs the resulting gas mixture exiting the chlorinationchamber may include many different compounds not otherwise discussed herein. In the UCI4 collection chamber 206, temperature or pressure may be slightly reduced from that of the chlorination chamber 204 in order to induce the deposition of solid UCI4 into a solid phase. In the embodiment shown, the temperature of the UCI4 collection chamber 206 is maintained below deposition temperature. In some examples, below 500°C or from about 25°C to about 500°C. The gas mixture is maintained in the collection chamber 206 for sufficient time to allow most or all of the UCI4 to achieve solid form. In an alternative embodiment, the conditions in the collection chamber 206 may be controlled to condense the UCI4 into a liquid form instead of a solid form.

[0050] FIG. 2 further illustrates a third chamber 208 for the collection of low boiling point fission products and any other products that may depose or condense out of the gas. In an embodiment, the conditions of the UCI4 collection chamber 206 and the other products collection chamber 208 may be controlled so that as pure a UCI4 deposition product as possible is obtained in the UCI4 collection chamber 206.

[0051] In the embodiment shown in FIG. 2, the different chambers 204, 206, 208 may be physically different vessels connected via valves and piping or may represent different locations in within a single continuous vessel. In a single vessel embodiment, transferring of gas from one chamber to another may be achieved by maintain a flow of gas through the single vessel. If physically different vessels are used for each chamber, the CBV separation process may be done either as a batch process or a continuous process or any combination of the two. Each chamber may be independently temperature controlled and may be provided with independent heating and / or cooling systems. Alternatively, the temperature of the chambers may be controlled solely by selection of the inlet Ar / CCE gas temperature, pressure, and flow rate and the amount of ambient heat loss from the equipment during the separation. As long as the desired conditions are maintained, any method and equipment for controlling the conditions in the different chambers may be utilized.

[0052] FIG. 3 illustrates an embodiment of a larger waste handling process 300 showing how the CBV method of FIG. 1 can be incorporated into a UNF handling and disposal system. The CBV separation method is particularly suitable when considering the larger picture of UNF disposal where, not only can it be used to recover valuable uranium from the UNF, the CBV separation method described herein has the addedbenefit over other methods of reducing the overall mass of the waste UNF thereby reducing disposal costs.

[0053] As shown in FIG. 3, UNF 302 is chlorinated in a conversion step 304 to convert the uranium into the chloride salt form as described above. Multiple separations and disposal steps then follow based on the material, to separate the constituents of the product mixture(s), which may include a mixture of uranium, high- temperature FPs, and other compounds 306a, and a mixture of low temperature FPs 306b. As mentioned above, significant value lies in the uranium. The uranium is, of course, removed as UC14 308 and can be converted chemically to UCI3 (a feed for some molten salt reactor designs) or to uranium metal from which new nuclear fuel could be made.

[0054] Plutonium and high melting temperature fission products 410, which remain with the solid UNF after the chlorination and sublimation operation, could be sent to a repository (refer to Option 1) for disposal or, alternatively, could be used as a starter fuel 312 for some advanced reactor designs (refer to Option 2). Furthermore, recovery of plutonium can be done as part of the processing of a co-waste stream laden with noble metals, rare-earth fission products, and minor actinides, which is beneficial for non-proliferation goals.

[0055] Finally, the low temperature FPs 306b that are collected in the other products collection chamber of FIG. 2 could be appropriately packaged and sent to a repository for disposal.

[0056] As noted above, at least 90% of the mass of UNF is typically uranium oxide. Thus, using the CBV separation method to selectively remove the uranium oxide from the rest of the UNF will drastically reduce the mass of the remaining UNF that must be disposed of. This is very beneficial beyond the normal cost savings in the recovery of the uranium when one considers that the space in a disposal repository is finite and not necessarily subject to normal economic pressures.

[0057] FIG. 4 illustrates another embodiment of a larger waste handling process 400 showing how the CBV method of FIG. 1 can be incorporated into a UNF handling and disposal system. In this figure, some preliminary preparations steps of the used fuel are shown, such as decladding 402 of the UNF and a voloxidation step 404 for the preliminary removal of fission gases prior to the chlorination 406 of the UNF. The decladding step 402 intakes the UNF, and outputs separately fission gasses, mixedoxides, and cladding. The mixed oxides are received at the Voloxidation (or volumetric oxidation) 404 step, which involves heating oxide fuel with oxygen, sometimes with alternating oxidation and reduction, or alternating oxidation by ozone to uranium trioxide with decomposition by heating back to triuranium octoxide. The voloxidated mixed oxides are then received at the chlorination (e.g. carbochlorination) step 406.

[0058] Downstream of the chlorination step 406, a stream containing CO2, volatiles, and UCI4 is passed through a condensation step 408 (for example, through a condenser), that causes separation of the UCI4, volatiles, and low-boiling chlorides and CO2. The low-boiling chlorides and CO2 may then pass through a secondary condensation step 410 (for example, at a second condenser), that causes separation of the low-boiling chlorides and the CO2. A waste-processing step 412 may process both the low-boiling chlorides as well as other chlorides (for example, TRU chlorides and FP chlorides of a residue stream generated at chlorination step 406), forming a waste stream.

[0059] EXAMPLES

[0060] The focus of these tests was to establish the basic experimental parameters required for the chlorination and subsequent volatilization of uranium and select fission product surrogates. A total of twenty-four (24) examples are discussed herein, studying the chlorination and volatilization of surrogate oxide UNF and determining the basic parameters: flow rate, temperature, and experimental setup for their separation. The tests described were all conducted at approximately 10-gram scale of uranium, and later results produced > 95% yield and purity of the uranium stream.

[0061] Experimental Method

[0062] FIG. 5 illustrates the basic experimental apparatus 500 used for separating uranium from a surrogate UNF material. FIGS. 6A-6C and FIG. 7 illustrate portions of the experimental apparatus used to generate the experimental data. Note that FIG. 6B illustrates a single-zone furnace, utilized in Examples, 1-17; FIG. 7 illustrates a multizone furnace 700, including a first zone 702, second zone 704, and third zone 706. The multi-zone furnace 700 was utilized for Examples 18-24. Each of first, second, andthird zones 702, 704, and 706 may be controlled separately, and may be maintained / operated at the same or different temperatures over time.

[0063] Quartz working tubes were used for all experiments. Vacuum seal flanges with barbed connectors were used for gas supply and outlet gas connections. A quartz boat was used to contain all starting materials and standard 60 mm tube furnace was used for all experiments. All tubing for supply and outlet gases were chosen for chemical and connection (barbed or swage) compatibility.

[0064] A three-neck round bottom flask 502 was used to contain the CCh for all experiments. Each neck served an individual purpose, the first as a gas outlet and delivery to the working tube, the second as a non-sparging Ar inlet and the third was equipped with a glass gas dispersion tube for sparging CCI4. The volume of CCh was measured at the start and end of several experiments to obtain an average amount of reactant used during each chlorination. FIG. 6A illustrates an example tee 602 for use in switching between sparging and non-sparging inlets to a round bottom flask. An example Ar (argon) inlet 604 is also illustrated, as well as a CCWAr outlet 608. Sparger 606 is utilized during sparging operations, and Ar inlet 610 is utilized without sparging operations.

[0065] For all experiments, the reactant(s) was weighed, mixed (if applicable) and added to the quartz boat 506. In Examples 1-17, The quartz boat 506 was then positioned in the center of the single heated zone 508 (at the inlet end of the working tube 504 illustrated by the three heating lines in FIG. 5). In Examples 18-24, The quartz boat 506 was then positioned in the center of a first heated zone (at the inlet end of the working tube 504; refer also to heated zone 1 801, 901 of FIGS. 8 and 9B). FIG. 6B illustrates an example fumace / heater 612, which at least partially surrounds / encloses an outer diameter of the working tube. A solids / liquids trap 510 was situated just downstream of the working tube outlet to aid in collection of any excess CCh and / or any solids that made it past the end of the tube. Following the solids / liquids trap 510 was positioned a bubbler 512, containing mineral oil and a check valve, for monitoring gas flow and to prevent back flow of normal atmosphere into the working tube. Outlets gases were plumbed to a KOH scrubber 514 located in the adjacent fume hood 516. FIG. 6C illustrates examples of a liquids / solids trap 614 downstream of the working tube, a mineral oil bubbler 616 downstream of the trap 614, and the gas outlet 618 to a fume hood.

[0066] The first 11 Examples (Experiments OX-1 through 11) utilized Mo foil as a collection mechanism for the UCU product as this had been done in the past for UCh and UCh purifications. It was not immediately clear that the Mo foil was reacting with the CCI4 but as experiments progressed the deterioration of the foil was apparent. The foil was utilized until a replacement collection tool was received: quartz tubes. For these first 11 experiments, the reported yield may be influenced by the addition of Mo as an impurity. The experiments performed with the quartz tubes for collection did not have this issue.

[0067] Single-zone furnace testing found that much of the starting UO2 material became overchlorinated to form UCI5 and UC16 rather than the desired UCI4. These higher chloride species are more volatile than UCh and resulted in difficult to track mass losses in yield. Modifications to the experimental setup were made to increase the UCh yield by trapping the higher chlorides and decomposing them to UCh. The higher uranium chlorides may be thermally decomposed to UCh at approximately 200 °C. A multi-zone furnace 700 (see FIG. 7) was designed and fabricated to allow for several heated zones 702, 704, 706 on the tube furnace. Thus, the objective was to have a multiple heated zones that would ensure that the UCh product would deposit at temperatures below its sublimation point while simultaneously decomposing any higher uranium chloride back to UCh to maximize uranium recovery. Experiments corresponding to Examples 18-24 were thus conducted to optimize the conditions for improving the yield of high purity UCh and are described below. Due to the modified multi-zone furnace design, optimal temperatures are slightly different than in experiments corresponding to Examples 1-17.

[0068] Prior to each experiment, a leak check was performed for the glovebox and the experimental setup. First, the glovebox was left undisturbed while observing for any changes in pressure for a minimum period of 10 minutes. The pressure inside of the reactor was only slightly above ambient conditions. Second, the experimental setup would be checked for leaks while flowing Ar through the experimental setup and observing the pressure of the glovebox. If the pressure of the glovebox remained stable during the leak check, it was deemed leak free and experiments were free to continue. If a leak was detected during the check, it would need to be addressed before proceeding with the experiment. No heating of furnaces may occur during the leakcheck process. All gas lines exterior to the glovebox are leak checked when initial connections are made and then rechecked monthly.

[0069] EXAMPLE 1: OX-1: Oxide Experiment #1

[0070] Experimental Setup

[0071] A 60 mm OD by 600 mm long working tube was centered into the tube furnace, 9.9940 g of UO2 was added into a quartz boat and the boat was centered in the heated zone. Mo foil was place on either side of the heated zone, in the cool zone to aid in product collection. The tube was sealed with vacuum flanges and attached to the inlet and outlet gas lines. For this experiment, the round bottom flask containing CCI4 was warmed with a heating mantel.

[0072] Synthesis and Observations

[0073] Once the furnace reached 500°C, the gas flow was switched to sparging through CCI4 and the heating mantel was set to 80°C. A brown material rapidly began to collect on both inlet and outlet end of the working tube. The heating mantel spiked in temperature causing the CCI4 to boil rapidly. Approximately 15 minutes into the experiment, sparging was stopped and the heating for the furnace and heating mantel were stopped. A large amount of dark red liquid was collected in the solid / liquid trap, believed to be uranium dissolved in CCI4. All components were allowed to cool to room temperature while flowing Ar before proceeding.

[0074] Once cooled, the liquid / solid trap and mineral oil bubbler were replaced, and the boat remains were weighed and replaced in the working tube. Once all materials were replaced, a leak check was performed and the reaction was restarted while flowing Ar, no CCI4 was used for the remainder of this experiment. The temperature was ramped from 500°C to 700°C in 50°C increments, allowing for an approximately one- hour dwell time between temperature increments. Observations were made at each temperature increment, primarily focused on the volatilization of the boat remains.

[0075] Products were collected, separated by color and analyzed via p-XRD.

[0076] EXAMPLE 2: OX-2: Oxide Experiment #2

[0077] Experimental Setup

[0078] A 60 mm OD by 600 mm long working tube was biased to the inlet side of the tube, lengthening the outlet portion of the tube. Mo foil was again used for productcollection. 11.3691 g of UO2 was placed into a quartz boat and loaded into the tube, placed in the center of the heated zone. The round bottom flask of CCU was not heated.

[0079] Synthesis and Observations

[0080] Sparging of CCI4 started once T=500°C, flowrate at ~8 bubble bursts / min.After one hour the temperature was increased to 550°C, there was a notable increase in the reaction rate. After another hour the temperature was raised to 600°C. After two hours at this max temperature, only a small amount of material on either end of the quartz boat remained.

[0081] Product continued to freeze on both inlet and outlets sides of the tube. Solids traveled past the end of the working tube and deposited in the outlet tubing and solid trap.

[0082] Products were collected and analyzed via XRD.

[0083] EXAMPLE S: OX-3: Oxide Experiment #3

[0084] Experimental Setup

[0085] The setup was similar to OX-2 but the length of the tube was increased to 1 m to increase the length of the cold section. 11.4625 g of UO2 was placed into the quartz boat and loaded into the working tube.

[0086] Synthesis and Observations

[0087] 600°C was the target temperature for the chlorination and volatilization and a flowrate of about 50 bubbles / min was used for a total of 5 hours of chlorination time.

[0088] A large amount of brownish-red material, believed to be UCI5 was produced during this reaction. Product continued to freeze on both sides of the heated zone.

[0089] Products were collected and analyzed via XRD.

[0090] EXAMPLE 4: OX-4: Oxide Experiment #4

[0091] Experimental Setup

[0092] The setup was similar to OX-2 but the OD of the tube was reduced to 25 mm. 14.2714g of UO2 was added to the quartz boat.

[0093] The temperature of the reaction was increased from 500°C to 600°C throughout the course of the reaction. A large portion of brownish-red material exiting the reaction tube but no material freezing on the inlet side of the tube. Experiment was not completed due to the amount of material surpassing the end of the working tube.

[0094] No products were collected or analyzed.

[0095] EXAMPLE S: OX-5: Oxide Experiment #5

[0096] Experimental Setup

[0097] This was a repeat of OX-4 but cooling fins were placed on the outlet side of the tube. This was also the first experiment with a flow meter to monitor the flow rate versus bubble counting. 11.8143 g of UO2 was added to the boat.

[0098] Synthesis and Observations

[0099] The flowrate was adjusted throughout the beginning of the experiment before settling on 60 mL / min. The temperature of this experiment was fluctuated, chlorinating at 500°C, then stopping the sparging of CCI4 and increasing the temperature to 650°C to volatilize the UCI4 produced during the chlorination period. This cycle was carried out for approximately 8 hours. The reaction was stopped when the boat was empty.Nearly all of the uranium remained inside of the working tube.

[0100] EXAMPLE 6: OX-6: Oxide Experiment #6

[0101] Experimental Setup

[0102] Repeat of OX-5 with 12.5375g of UO2.

[0103] Synthesis and Observations

[0104] Throughout the course of the experiment the flowrate was held at 60 mL / min and 575°C. After 7.5 hours of reaction time, the boat was empty, and the reaction completed. Some material made it past the end of the working tube, but it seems to have been minimized.

[0105] EXAMPLE 7: OX-7: Oxide Experiment #7

[0106] Experimental Setup

[0107] Repeat of OX-5, with 11.9080g of U3O8 as the starting material.

[0108] Synthesis and Observations

[0109] Repeat of the synthesis conditions for OX-6. The boat was empty after 6.5 hours of reaction time. A larger quantity of brownish-red material, believed to be UCI5 was produced and traveled out of the reaction tube and into the solids trap.

[0110] EXAMPLE S: OX-8: Oxide Experiment #8

[0111] Experimental Setup

[0112] Repeat of OX-5 with 11.9198g of U3O8 as the starting material.

[0113] Synthesis and Observations

[0114] The flowrate remained at 60 mL / min throughout the course of the experiment. Some thermal cycling between the 550°C chlorination temperature and 600°C volatilization temperature.

[0115] Once the reaction was complete, the reduction of UCls was attempted by reversing the flow of Ar and slowing increasing the temperature from 100°C to 300°C.

[0116] Some UCI5 still made it past the end of the working tube and into the solids trap.

[0117] EXAMPLE 9: OX-9: Oxide Experiment #9

[0118] Experimental Setup

[0119] Repeat of OX-5, with 11.7162g of U3O8 as the starting material.

[0120] Synthesis and Observations

[0121] For this experiment 3% H2, balance Ar, was used as a sparging gas. The reaction was started at 550°C and increased to 575°C about 3 hours into the experiment.

[0122] The rate of reaction was slowed with the use of hydrogen.

[0123] EXAMPLE 10: OX-10: Oxide Experiment #10

[0124] Purpose

[0125] Longer tube length and cooling fins in an attempt to contain UCI5 to the tube.

[0126] Experimental Setup

[0127] A 25mm OD tube with 1.2 m length, biased to the inlet side of the tube. Multiple lengths of cooling fins added to the outlet portion of the tube length. An internal cooling fin was added to the cool zone. 10.5745g of U3O8 as the starting material.

[0128] Synthesis and Observations

[0129] Temperature held at 575°C for the length of the experiment. 3% H2:balance Ar was used as a sparging gas, held at 60 mL / min.

[0130] Increased production of UCb versus OX-9. Only a small amount of material froze onto the internal cooling fin.

[0131] UCI5 reduction attempted without reversing the flow Ar but was mostly unsuccessful.

[0132] EXAMPLE 11: OX-11: Oxide Experiment #11

[0133] Purpose

[0134] Determine if the UCI5 is traveling down the outlet path as a gas or as a solid entrained in the gas stream. Smaller scale to shorten the length of experiment.

[0135] Experimental Setup

[0136] 25 mm O.D. and 600 mm length tube, with a cooling fin. Balls of quartz wool were placed at the edge of the boat and every -100 mm down the outlet length of the working tube to act as filters. 5.1199g of U3O8 as the starting material.

[0137] Synthesis and Observations

[0138] A temperature of 575°C, flowrate of 60 mL / min and Ar sparging gas were used throughout the experiment.

[0139] Nearly all material was stopped by the first quartz wool ball in the cold zone.

[0140] EXAMPLE 12: OX-12: Oxide Experiment #12

[0141] Purpose

[0142] Perform experiment with vertical tube orientation to increase reactant surface area.

[0143] Experimental Setup

[0144] A 50 mm OD, 600mm length working tube with a 150 micron - 200 micron quartz frit was used. The furnace was lifted into the vertical orientation and 11.6355g of UO2 was placed on top of the frit. No cooling fins were used for this experiment.

[0145] Synthesis and Observations

[0146] The reaction rate did not appear to increase with increased surface area, finishing within the same amount of time as previous experiments.

[0147] An increased flowrate could be beneficial. The orientation of the furnace leads to the top flange getting quite hot throughout the course of the experiment.

[0148] EXAMPLE 13: OX-13: Oxide Experiment #13

[0149] Purpose

[0150] Repeat OX-12 but add insulation and cooling fin to the outlet portion of the tube and increase the flowrate of the CC14 to accommodate the increased diameter of the working tube.

[0151] Experimental Setup

[0152] Repeat of OX-12 but add insulation and cooling fin to the outlet portion of the tube. 6.5269g of UO2 was placed on top of the frit and a quartz wool ball placed at the outlet of the top of the furnace.

[0153] Synthesis and Observations

[0154] Temperature of 575°C and flow rate of 120 mL / min was used throughout the experiment.

[0155] Not much of a difference between OX- 12 and OX-13.

[0156] EXAMPLE 14: OX-14: Oxide Experiment #14

[0157] Purpose

[0158] Attempt direct processing of UO2 pellets.

[0159] Experimental Setup

[0160] Part one of the experiment took place in the 25mm OD x 600 mm long working tube used in many previous experiments, three pellets weighing 12.2132g of UO2 was placed into the boat.

[0161] For the second part of the experiment the remains of the pellets, 10.5686g of partially reacted UO2 was placed onto the frit of the horizonal working tube.

[0162] Synthesis and Observations

[0163] Part one proceeded very slowly compared to using the powdered UO2.

[0164] Part two continued to proceed slowly but an increased temperature, from 575°C to 650°C was used to accelerate the rate of the reaction.

[0165] There appears to have been an increased amount of UCI5 produced.

[0166] EXAMPLE 15: OXFP-1: Oxide Fission Product Experiment #!

[0167] Purpose

[0168] Use one, expected, volatile and non-volatile surrogate fission product for initial testing.

[0169] Experimental Setup

[0170] 2.0434g of lanthanum oxide and 1.9843g of zirconium oxide were added to the boat and loaded into the 25mm OD x 600mm length working tube.

[0171] Synthesis and Observations

[0172] A temperature of 575°C and flowrate of 60 mL / rnin was used throughout the experiment. A white colored material was observed freezing outside of the furnace. The reaction was stopped after 5 hours of reaction time.

[0173] Products were collected and analyzed via XRD.

[0174] EXAMPLE 16: OXFP-2: Oxide Fission Product Experiment #2

[0175] Purpose

[0176] Mixing a highly volatile fission product surrogate with UO2 to observe how much of a separation occurs with the current furnace setup.

[0177] Experimental Setup

[0178] The 25mm OD x 600mm length working tube was used. Quartz wool balls were place every 3 inches on the outlet side of the boat. Into the boat was added the well mixed uranium and zirconium, 5.0787g of UO2 and 0.4036g of Z1O2.

[0179] Synthesis and Observations

[0180] The established temperature of 575°C and flowrate of 60 mL / min was used. After 3.5 hours of reaction time, the boat was empty. There was a visible gradient of materials; UCh-ZrCh-UCls, starting closest to the heated zone and extending into the cold zone.

[0181] EXAMPLE 17: OXFP-3: Oxide Fission Product Experiment #3

[0182] Purpose

[0183] Uranium and fission product surrogate’s that were mentioned in the SOPO Milestone 1.1.

[0184] Experimental Setup

[0185] Into the 25mm OD x 600mm length working tube, the boat containing the species of interest were added; 8.0476g UO2, 0.0711g SnI2, 0.0518g SrO, 0.2138g Nd2O3, 1.8950g CeO2.

[0186] Synthesis and Observations

[0187] The established temperature of 575°C and flowrate of 60 mL / min was used. A purple gas was observed in the heated zone and brown gas in the cool zone as soon as heating began. The reaction appeared to be complete after 6 hours.

[0188] Table 2 captures species concentration data that demonstrates the purity of the collected UCU product. Quantitative separation from the added fission products is demonstrated, because the recovered product does not have detectable amounts of contaminants. The recovered yield of this reaction was 96.4% of the original uranium. A small portion of the uranium was also found to be entrained with the more volatile tin chloride species further down the (reaction) tube, though there was only 4.6 mg of recovered material from this product fraction. The remainder of the uranium balance can be found in the non-volatilized boat material containing 310 mg of UCI4. It is likely that this material did not sublimate due to not allowing the reaction to run long enough at temperature.

[0189] Table 2: OXFP-3 Species Concentrationsa Limit of detection is less than 0.01% for the reported data. b Detector was saturated indicating significant concentration of Sn.

[0190] EXAMPLE 18: MZF-1: Multizone Furnace Experiment #1

[0191] Purpose

[0192] Demonstrate and commission the multizone furnace experimental design, and gain insight on initial temperature set points.

[0193] Experimental Setup

[0194] Into the 50 mm OD x 600 mm length working tube, the boat containing UO2 was added using a 5 g of U basis and was placed within the high temperature, first furnace zone.

[0195] Synthesis and Observations

[0196] Furnace zone 1 was set to 600 °C and furnace zone 2 was set below the expected sublimation temperature of UCU at 500 °C. The reaction proceeded as previous tests have with dark green UCI4 crystals depositing following the 500 °C furnace zone. This indicated that the temperature gradient was not significant enough to allow UCI4 to cool and deposit in the second furnace zone. No data on the minimization of UCI5 and UC16could be gathered as a result of the location of UCU deposition.

[0197] EXAMPLE 19: MZF-2: Multizone Furnace Experiment #2

[0198] Purpose

[0199] Use a lower furnace zone 2 temperature to enable UCI4 deposition.

[0200] Experimental Setup

[0201] Into the 50 mm OD x 600 mm length working tube, the boat containing UO2 was added using a 5 g of U basis and was placed within the high temperature, first furnace zone.

[0202] Synthesis and Observations

[0203] Furnace zone 1 was set to 600 °C and furnace zone 2 was set at 400 °C. Following chlorination and sublimation of the starting uranium, dark green UCI4 crystals began depositing in between the two furnace zones. In this experiment, the temperature gradient resulted in uranium depositing before the second furnace section. Notably, there was less visible formation of brown / red UCI5 observed downstream of the furnace zones. Instead, a small amount of green material was observed past furnace zone 2. This suggested successful thermal decomposition of the brown / red UCls to green UCI4 following its residence time in furnace zone 2.

[0204] EXAMPLE 20: MZF-3: Multizone Furnace Experiment #3

[0205] Purpose

[0206] Use a significantly lower furnace zone 2 temperature to enable UCI4 deposition and facilitate UCI5 and UCle decomposition by adding a quartz frit filter to increase residence time in hot zones.

[0207] Experimental Setup

[0208] Into the 50 mm OD x 600 mm length working tube, the boat containing UO2 was added using a 5 g of U basis and was placed within the high temperature, first furnace zone.

[0209] Synthesis and Observations

[0210] Furnace zone 1 was set to 600 °C and furnace zone 2 was set at 200 °C to still be above the thermal decomposition temperatures for the higher uranium chlorides.Following chlorination and sublimation of the starting uranium, dark green UCI4 crystals began depositing in between the two furnace zones. In this experiment, the temperature gradient was too steep resulting in uranium depositing on the porous quartz frit before the second furnace section. Any produced UCI5 or UCU were, however, decomposed evidenced by the presence of green deposits in the second furnace zone. Future optimization sought to better control where the material is decomposed to create a tighter band of UCU.

[0211] EXAMPLE 21: MZF-4: Multizone Furnace Experiment #4

[0212] Purpose

[0213] Use a seed crystal of UCI4 to promote UCI4 deposition inside the second furnace zone.

[0214] Experimental Setup

[0215] Into the 50 mm OD x 600 mm length working tube, the boat containing UO2 was added using a 5 g of U basis and was placed within the high temperature, first furnace zone. In the second furnace zone, a small (< 50 mg) single crystal of UCU was placed directly on the quartz vessel.

[0216] Synthesis and Observations

[0217] Furnace zone 1 was set to 600 °C and furnace zone 2 was set at 200 °C to still be above the thermal decomposition temperatures for the higher uranium chlorides.Following chlorination and sublimation of the starting uranium, dark green UCU crystals began depositing in between the two furnace zones. The seed crystal did not appear to significantly affect UCU deposition.

[0218] EXAMPLE 22: MZF-5: Multizone Furnace Experiment #5

[0219] Purpose

[0220] Demonstrate separation of U from Ce, Nd, Zr, Sn, and Sr, using the multizone furnace.

[0221] Experimental Setup

[0222] Into the 50 mm OD x 600 mm length working tube, the boat containing UO2 was added using a 5 g of U basis and was placed within the high temperature, first furnace zone with a mixture of simulated fission products.

[0223] Synthesis and Observations

[0224] Furnace zone 1 was set to 600 °C and furnace zone 2 was set at 200 °C to still be above the thermal decomposition temperatures for the higher uranium chlorides as well as the volatile Zr chlorides. Following chlorination and sublimation of the starting simulated used fuel mixture, dark green UCk crystals began depositing between the two furnace zones. More volatile species like Sn and Zr were observed downstream of the second furnace zone, but were entrained with UCU that was formed from decomposition of higher uranium chlorides.

[0225] EXAMPLE 23: MZF-6: Multizone Furnace Experiment #6

[0226] Purpose

[0227] Demonstrate and optimize separation of U from Ce and Zr.

[0228] Experimental Setup

[0229] Referring to FIG. 8, which illustrates a schematic 800 of an example working tube 804, into the 50 mm OD x 600 mm length working tube 804, the boat 806 containing UO2 was added using a 5 g of U basis and was placed within the high temperature, first furnace zone 1 801 with a mixture of simulated fission products. A plug of quartz wool 810a was also placed within the second furnace zone 2 803.

[0230] Synthesis and Observations

[0231] Referring also to FIG. 8, furnace zone 1 801 was set to 600 °C, and furnace zone 2 803 was set at 200 °C to still be above the thermal decomposition temperatures for the higher uranium chlorides as well as the volatile Zr chlorides. A 15 cm section of quartz wool 810a was placed inside the second furnace zone 2 803 to trap the uranium chlorides in the 200 °C zone 2 803 for longer, promoting a tighter band of UCI4 deposition while facilitating movement of more volatile Z1CI4. Following chlorination and sublimation of the starting simulated used fuel mixture, dark green UCk crystals 812 began depositing on the quartz wool 810a starting right before the second furnacezone 2 803 as shown in FIG. 8. A tight band of UCh 812 was also observed to trail from the crystals on the quartz wool, indicating that the wool successfully increased the residence time of the gas to promote thermal decomposition. More volatile Z1CI4 species 814 were observed downstream of the second furnace zone 2 803, into the third furnace zone 3 805, as a yellow / orange band. Quartz wool 810b was also placed within the third furnace zone 3 805. Cerium chloride 808 remained in the quartz reaction boat 806.

[0232] EXAMPLE 24: MZF-7: Multizone Furnace Experiment #7

[0233] Purpose

[0234] Demonstrate capability of using U3O8 starting material

[0235] Experimental Setup

[0236] Referring to FIG. 9B, which illustrates a schematic 900 of an example working tube 904, Into the 50 mm OD x 600 mm length working tube 904, the boat 906 containing U3O8 was added using a 5 g of U basis and was placed within the high temperature, first furnace zone 1 901 with a mixture of simulated fission products. Baffle 910 was placed within the second furnace zone 2 903 (and, in some examples, extended into the third furnace zone 3 905).

[0237] Synthesis and Observations

[0238] Furnace zone 1 901 was set to 600 °C and furnace zone 2 903 was set at 200 °C to still be above the thermal decomposition temperatures for the higher uranium chlorides. Previous single-zone furnace experiments demonstrated the ability to chlorinate U3O8 directly. However, the observed significant production of UCI5 and UC16which affected yields and made cleanup difficult. U3O8 was tested here using the multizone furnace (for example, furnace 700) to demonstrate the ability to mitigate the formation of higher uranium chlorides in a single step synthesis and separation. In place of the (sometimes inconsistent) quartz wool 810a-b of Example 23, a stainless-steel baffle 910 was designed and fabricated to promote a tortuous path for the gas flow in the second furnace zone 2 903. FIG. 9 A shows a front perspective view of an example baffle 910; other shapes and designs may be contemplated. The baffle 910 utilized in the particular example is stainless steel; however, other suitable materials compatible with the conditions and environment may be contemplated. Dark UCh crystals 912a are observed at the front of the steel gas baffle 910. Green deposits of UCI4 912b areobserved further downstream of the gas baffle 910 due to thermal decomposition of more volatile, higher uranium chlorides.

[0239] Results

[0240] The experiments, described above, refined the basic parameters for the chlorination and bulk separation of uranium from fission product elements. Table 3 captures the yield results for each test of Examples 1-17, along with the basic parameters.

[0241] Several factors should be noted when considering the yield for each experiment. The use of Mo foil in Experiments OX-1 thru OX-11 may have artificially inflated the yields on these experiments. Experiments where ICP-OES data is available are listed in table whatever. The presence of UCI5 in the product may also attribute to the reduction of uranium purity, as UCU was considered the primary component when calculating the theoretical yield.

[0242] The experiments demonstrating the proof of concept after determining the basic parameters, such as temperature and flow rate are Experiments OX-6, OX-7 and OXFP-3. These are the most straightforward experiments when considering yield, and of those the Experiment OXFP-3 were performed without the troublesome Mo foil.Table 3: Summarized Results for Examples 1-17

[0243] The lowest temperature that appears to maximize the reaction kinetics is 575°C. Through experimentation, it was also determined that the container of CC14reactant, does not need to be heated to induce volatilization of the CC14, and that sparging at a rate of approximately 60 mL / min (This is taking into account the conversion from air to Ar, i.e., 70mL / min setting really corresponds 60mL / min Ar) is sufficient in volatilizing a sufficient amount of CC14, this simplifies the experimental setup. Argon, as well as 3% hydrogen with a balance of argon, has been used as a sparging gas in experiments. The addition of dilute (about 3% in the particular experiments) hydrogen aids in reducing the amount of UC15 produced during the reaction but also decreases the reaction rate.

[0244] Aiding in the reactor design, testing revealed that the ratio of the diameter of the inlet gas stream and the inner diameter of the working tube is important when considering gas flow currents inside of the working tube and maintaining the products moving downstream of the working tube. Experimentation has also determined that a filter material will be useful to prevent the movement of UCls beyond its temperaturebased freezing zone.

[0245] The results of these experiments indicate that the bulk separation of uranium from a surrogate used nuclear fuel matrix with yield and purity at least 95% uranium is possible. The basic operating parameters are a temperature of 575°C and flow rate of 60 mL / min sparging through ambient temperature CCI4. Progress has been made in terms of feasibility of product collection, utilizing quartz inner tubes but more work is needed for developing a suitable filter for UCls.Further experimentation including multi-zone furnaces (and the inclusion of a baffle or other means of providing a tortuous path for reacting gasses within the working tube) showed significantly improved yield for UCI4 formation with no observation of brown / red UCh, and proved the viability of using U3O8 as a starting reagent.

[0246] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained.

[0247] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the technology are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however,inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0248] It will be clear that the systems and methods described herein are well adapted to attain the ends and advantages mentioned as well as those inherent therein. Those skilled in the art will recognize that the methods and systems within this specification may be implemented in many manners and as such are not to be limited by the foregoing exemplified embodiments and examples. In this regard, any number of the features of the different embodiments described herein may be combined into one single embodiment and alternate embodiments having fewer than or more than all of the features herein described are possible.

[0249] While various embodiments have been described for purposes of this disclosure, various changes and modifications may be made which are well within the scope contemplated by the present disclosure. For example, a number of process optimization changes could be done depending on the scale throughput of a CBV separation system such as using a fluidized bed reactor for the chlorination and sublimation chamber to increase the kinetics of the reaction. Likewise, including filters between chambers to prevent physical carry over of compounds was also seen as potentially beneficial from the examples and tests performed. Numerous other changes may be made which will readily suggest themselves to those skilled in the art and which are encompassed in the spirit of the disclosure.

[0250] Illustrative examples of the systems and methods described herein are provided below. An embodiment of the system or method described herein may include any one or more, and any combination of, the numbered clauses described below:

[0251] 1. A method for separating uranium from a solid material containing solid uranium oxide metal and at least 1% by weight other material, the method comprising: maintaining the solid material containing the uranium oxide under UC14 sublimating conditions in a chlorinating environment for a period of time sufficient to convert at least some solid uranium oxide into UCI4 in a gas phase.

[0252] 2. The method of clause 1 , wherein the uranium oxide is selected from UO2 or U3O8.

[0253] 3. The method of any of clauses 1-2, wherein the sublimating conditions include a pressure between about 0.1 atm to about 10 atm and a temperature between about 450°C and about 700°C.

[0254] 4. The method of clause 3, wherein the sublimating conditions include a between about 0.9 atm to about 1.5 atm and a temperature between about 500°C and about 650°C.

[0255] 5. The method of any of clauses 1-4, wherein the solid material is used nuclear fuel comprising at least one fission product of uranium.

[0256] 6. The method of any of clauses 1-5, further comprising preparing the solid material by crushing or pulverizing it into a powder or aggregate.

[0257] 7. The method of any of clauses 1-6, further comprising placing the solid material into a chlorination chamber, the chlorination chamber containing the chlorinating environment.

[0258] 8. The method of any of clauses 1-7, wherein the maintaining step includes contacting the solid material with CC14.

[0259] 9. The method of clause 8, further comprising, prior to the maintaining step, sparging an inert gas mixture through a pool of CCI4 to generate a CCI4- containing gas.

[0260] 10. The method of clause 8, further comprising, under the sublimating conditions, reacting the solid uranium oxide with the CCI4 to create UCI4 and CO2.

[0261] 11. The method of any of clauses 1-10, further comprising separating the UCI4 from the gas phase by reducing a temperature of gas phase thereby by causing the UCI4 to depose from the gas phase as a solid.

[0262] 12. The method of clause 11, further comprising disposing of the solid material after removing the gas phase containing UCI4 from the solid material.

[0263] 13. The method of any of clauses 1-12, wherein the period of time is a sufficient to convert at least 20% of the solid uranium oxide into UCI4.

[0264] 14. The method of any of clauses 1-13, further comprising removing the gas phase containing the UCI4 from the solid material.

[0265] 15. The method of any of clauses 1-14, further comprising agitating the chlorinating environment.

[0266] 16. A system, comprising: a chlorination chamber configured to hold a solid material containing solid uranium oxide and a chlorination gas, wherein, within thechlorination chamber, the solid uranium oxide reacts with the chlorination gas to generate a UCh-containing gas mixture; and a UCI4 collection chamber configured to receive the UCk-containing gas mixture from the chlorination chamber, wherein a temperature within the UCI4 collection chamber is maintained below a deposition temperature of the UCI4.

[0267] 17. The system of clause 16, comprising a low boiling point fission products collection chamber downstream of the UCI4 collection chamber.

[0268] 18. The system of any of clauses 16-17, further comprising a condenser.

[0269] 19. The system of any of clauses 16-18, wherein the chlorination gas comprises CCI4.

[0270] 20. The system of any of clauses 16-19, wherein a pressure within the UCI4 collection chamber is maintained below a pressure within the chlorination chamber.

[0271] 21. The system of any of clauses 16-20, wherein the chlorination chamber and UCI4 collection chamber represent different locations within a single continuous vessel.

[0272] 22. A method for separating uranium from a solid material containing solid uranium oxide metal and at least 1% by weight other material, the method comprising: maintaining the solid material containing the uranium oxide in a chlorinating environment within a chlorination chamber for a period of time sufficient to convert at least some solid uranium oxide into UCI4 in a gas phase; and controlling conditions of a collection chamber to condense the UCI4 in the gas phase into a liquid form, wherein the collection chamber is configured to receive the UCI4 in the gas phase from the chlorination chamber.

[0273] 23. The method of clause 22, wherein the uranium oxide is selected from UO2 or UsOs.

[0274] 24. The method of any of clauses 22-23, wherein the solid material is used nuclear fuel.

[0275] 25. The method of any of clauses 22-24, further comprising preparing the solid material by crushing or pulverizing it into a powder or aggregate.

[0276] 26. The method of any of clauses 22-25, wherein the maintaining step includes contacting the solid material with CCI4.

[0277] 27. The method of clause 26, further comprising, prior to the maintaining step, sparging an inert gas mixture through a pool of CC14 to generate a CCI4- containing gas.

[0278] 28. The method of clause 26, further comprising, within the chlorinating environment, reacting the solid uranium oxide with the CCU to create UCI4 and CO2.

[0279] 29. The method of any of clauses 22-28, wherein the period of time is a sufficient to convert at least 20% of the solid uranium oxide into UCI4.

[0280] 30. The method of any of clauses 22-29, further comprising agitating the chlorinating environment within the chlorination chamber.

[0281] 31. The method of any of clauses 22-30, wherein the chlorination chamber and the collection chamber represent different locations within a single continuous vessel.

[0282] 32. The method of any of clauses 22-31 , further comprising maintaining the solid material containing the uranium oxide under UCI4 sublimating conditions within the chlorinating environment for the period of time.

Claims

CLAIMSWhat is claimed is:

1. A method for separating uranium from a solid material containing solid uranium oxide metal and at least 1% by weight other material, the method comprising: maintaining the solid material containing the uranium oxide under UC14 sublimating conditions in a chlorinating environment for a period of time sufficient to convert at least some solid uranium oxide into UCI4 in a gas phase.

2. The method of claim 1, wherein the uranium oxide is selected from UO2 or U3O8.

3. The method of any of claims 1-2, wherein the sublimating conditions include a pressure between about 0.1 atm to about 10 atm and a temperature between about 450°C and about 700°C.

4. The method of claim 3, wherein the sublimating conditions include a between about 0.9 atm to about 1.5 atm and a temperature between about 500°C and about 650°C.

5. The method of any of claims 1-4, wherein the solid material is used nuclear fuel comprising at least one fission product of uranium.

6. The method of any of claims 1-5, further comprising preparing the solid material by crushing or pulverizing it into a powder or aggregate.

7. The method of any of claims 1-6, further comprising placing the solid material into a chlorination chamber, the chlorination chamber containing the chlorinating environment.

8. The method of any of claims 1-7, wherein the maintaining step includes contacting the solid material with CCI4.

9. The method of claim 8, further comprising, prior to the maintaining step, sparging an inert gas mixture through a pool of CCI4 to generate a CC14-containing gas.

10. The method of claim 8, further comprising, under the sublimating conditions, reacting the solid uranium oxide with the CCI4 to create UCI4 and CO2.

11. The method of any of claims 1-10, further comprising separating the UCI4 from the gas phase by reducing a temperature of gas phase thereby by causing the UCI4 to depose from the gas phase as a solid.

12. The method of claim 11, further comprising disposing of the solid material after removing the gas phase containing UCI4 from the solid material.

13. The method of any of claims 1-12, wherein the period of time is a sufficient to convert at least 20% of the solid uranium oxide into UCI4.

14. The method of any of claims 1-13, further comprising removing the gas phase containing the UCI4 from the solid material.

15. The method of any of claims 1-14, further comprising agitating the chlorinating environment.

16. A system, comprising: a chlorination chamber configured to hold a solid material containing solid uranium oxide and a chlorination gas, wherein, within the chlorination chamber, the solid uranium oxide reacts with the chlorination gas to generate a UCU-containing gas mixture; and a UCI4 collection chamber configured to receive the UCU-containing gas mixture from the chlorination chamber, wherein a temperature within the UCI4 collection chamber is maintained below a deposition temperature of the UCI4.

17. The system of claim 16, comprising a low boiling point fission products collection chamber downstream of the UC14 collection chamber.

18. The system of any of claims 16-17, further comprising a condenser.

19. The system of any of claims 16-18, wherein the chlorination gas comprises CC14.

20. The system of any of claims 16-19, wherein a pressure within the UCI4 collection chamber is maintained below a pressure within the chlorination chamber.

21. The system of any of claims 16-20, wherein the chlorination chamber and UCI4 collection chamber represent different locations within a single continuous vessel.

22. A method for separating uranium from a solid material containing solid uranium oxide metal and at least 1% by weight other material, the method comprising: maintaining the solid material containing the uranium oxide in a chlorinating environment within a chlorination chamber for a period of time sufficient to convert at least some solid uranium oxide into UCI4 in a gas phase; and controlling conditions of a collection chamber to condense the UCI4 in the gas phase into a liquid form, wherein the collection chamber is configured to receive the UCI4 in the gas phase from the chlorination chamber.

23. The method of claim 22, wherein the uranium oxide is selected from UO2 or UsOs.

24. The method of any of claims 22-23, wherein the solid material is used nuclear fuel.

25. The method of any of claims 22-24, further comprising preparing the solid material by crushing or pulverizing it into a powder or aggregate.

26. The method of any of claims 22-25, wherein the maintaining step includes contacting the solid material with CCI4.

27. The method of claim 26, further comprising, prior to the maintaining step, sparging an inert gas mixture through a pool of CCh to generate a CCU-containing gas.

28. The method of claim 26, further comprising, within the chlorinating environment, reacting the solid uranium oxide with the CCh to create UCI4 and CO2.

29. The method of any of claims 22-28, wherein the period of time is a sufficient to convert at least 20% of the solid uranium oxide into UCI4.

30. The method of any of claims 22-29, further comprising agitating the chlorinating environment within the chlorination chamber.

31. The method of any of claims 22-30, wherein the chlorination chamber and the collection chamber represent different locations within a single continuous vessel.

32. The method of any of claims 22-31 , further comprising maintaining the solid material containing the uranium oxide under UCI4 sublimating conditions within the chlorinating environment for the period of time.

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