System and method for generating oxygen-deficient uranyl nitrate from dilute uranyl nitrate solution by diffusion dialysis and vacuum distillation
The system addresses the inefficiencies of existing uranyl nitrate production by using diffusion dialysis and vacuum distillation to separate nitrate ions from uranium ions, resulting in high-purity, NOx-free acid-deficient uranyl nitrate suitable for fuel production.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- X ENERGY LLC
- Filing Date
- 2024-06-07
- Publication Date
- 2026-07-07
AI Technical Summary
Existing processes for producing acid-deficient uranyl nitrate from dilute uranyl nitrate solutions result in the formation of solid powders that need redissolution and generate NOx emissions, necessitating a more efficient and emission-free method.
A system and method utilizing diffusion dialysis and vacuum distillation, comprising a feedstock evaporation system, diffusion dialysis system, and product evaporation system, to produce oxygen-deficient uranyl nitrate by boiling under vacuum, counterflowing solutions across membrane vessels, and separating nitrate ions from uranium ions.
The process effectively produces acid-deficient uranyl nitrate with reduced NOx emissions and enables the reuse of nitric acid, achieving high purity and concentration suitable for fuel production.
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Abstract
Description
Technical Field
[0001] This invention was made with government support under DE-NE0009040 awarded by the Department of Energy. The government has certain rights in this invention.
[0002] Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 472,048, filed on June 9, 2023 (which is still pending), the entire disclosure of which is incorporated herein by reference.
Background Art
[0003] The uranyl nitrate solution lacking acid is used in the solution gelation process for fuel production. The uranyl nitrate solution lacking acid typically has a uranium concentration between 2.80 M and 3.27 M, a nitric acid concentration of 4.5 M to 5.25 M, a density of 1.85 g / cc to 2.00 g / cc, and a NO3 / U molar ratio of 1.50 to 1.75.
[0004] The dilute uranyl nitrate solution is produced as a result of solvent extraction from spent fuel reprocessing, uranium recovery, or off-spec fuel solutions. The dilute uranyl nitrate solution may have a uranium concentration of less than 1 g / cc (<1 g / cc) and may have any nitric acid concentration.
[0005] A typical process for generating an acid-deficient uranyl nitrate solution from a dilute uranyl nitrate solution is to use direct denitration. This process produces solid powders that must be redissolved to produce the acid-deficient uranyl nitrate solution and NOx emissions that must be removed from the exhaust gas.
Summary of the Invention
Problems to be Solved by the Invention
[0006] In view of the above, it is desirable to have a process that enables the production of acid-deficient uranyl nitrate from a dilute uranyl nitrate solution.
Means for Solving the Problems
[0007] To address this need, the present disclosure provides a system and method for producing oxygen-deficient uranyl nitrate from dilute uranyl nitrate solutions by diffusion dialysis and vacuum distillation.
[0008] A brief overview of various embodiments and implementations is provided below. Some simplifications and omissions may be made in the following overview, intended to highlight and introduce some aspects of the embodiments and implementations disclosed herein, but not to limit the scope of the disclosure. A more detailed description of embodiments and implementations sufficient to enable those skilled in the art to create and use the ingenious concepts of the disclosure follows in later sections.
[0009] In one embodiment, the present disclosure provides a system including a feedstock evaporation system and a diffusion dialysis system.
[0010] The feedstock evaporation system is configured to receive the feedstock stream and remove water from the feedstock stream by boiling under vacuum to produce a concentrated uranyl nitrate solution and distilled water products.
[0011] The diffusion dialysis system is configured to receive concentrated uranyl nitrate solution and distilled water products; to counterflow the concentrated uranyl nitrate solution and distilled water products to the opposite side of multiple membrane vessels to facilitate the transfer of nitrate ions from the concentrated uranyl nitrate solution to distilled water; and to generate dialysate flow and recycled acid flow.
[0012] In some implementations, the feedstock flow includes the products of the solvent extraction process used to recycle spent nuclear fuel. However, in other implementations, the feedstock flow includes recovery flows from fuel manufacturing activities other than the solvent extraction process used to recycle spent nuclear fuel.
[0013] In another embodiment, the present disclosure provides a method comprising the steps of: in a feedstock evaporation system, boiling and removing water from a feedstock stream under vacuum to produce a concentrated uranyl nitrate solution and a distilled water product; and in a diffusion dialysis system, counterflowing the concentrated uranyl nitrate solution and the distilled water product to opposite sides of a plurality of membrane vessels to facilitate the transfer of nitrate ions from the concentrated uranyl nitrate solution to distilled water to produce a dialysate stream and a recycled acid stream.
[0014] In some implementations, the feedstock flow includes the products of the solvent extraction process used to recycle spent nuclear fuel. However, in other implementations, the feedstock flow includes recovery flows from fuel manufacturing activities other than the solvent extraction process used to recycle spent nuclear fuel.
[0015] Brief explanation of the drawing To better understand this disclosure, please refer to the attached drawings: [Brief explanation of the drawing]
[0016] [Figure 1] Figure 1 shows one configuration of a feedstock evaporation system. [Figure 2A] Figure 2A shows one configuration of a diffusion dialysis system. [Figure 2B] Figure 2B shows one configuration of a diffusion dialysis system. [Figure 2C] Figure 2C shows one configuration of a diffusion dialysis system. [Figure 3] Figure 3 shows one configuration of the product evaporation system. [Figure 4] Figure 4 shows one configuration of the recovery evaporation system. [Figure 5] Figure 5 shows one configuration of the overall system for producing oxygen-deficient uranyl nitrate from a dilute uranyl nitrate solution. [Modes for carrying out the invention]
[0017] Detailed description of the drawing Reference is now made to drawings that depict the same numbers as the same components or steps, and extensive aspects of various exemplary embodiments and implementations are disclosed.
[0018] The present disclosure is directed to systems and methods for producing uranium nitrate lacking in acid from a dilute uranium nitrate solution. In some implementations, the solution can be a product of a solvent extraction process used to recycle spent nuclear fuel or a recovery stream from other fuel manufacturing activities.
[0019] The various embodiments and implementations disclosed herein further relate to a process for producing uranium nitrate lacking in acid from a dilute uranium nitrate solution, including a feedstock evaporation system, a diffusion dialysis system, a product evaporation system, and a recovery evaporation system.
[0020] As discussed in more detail below, the feedstock evaporation system boils and removes water under vacuum to produce a concentrated uranium nitrate solution having excess acid and a distilled water product. In some implementations, the water recovery rate is adjusted based on the needs of the diffusion dialysis system, and the remainder is discharged as clean steam. The vacuum is provided by a venturi and suppresses NOx generation from the feedstock solution.
[0021] The diffusion dialysis system receives the concentrate and distillate from the feedstock evaporation system and flows them countercurrently across opposite sides of a membrane stack to facilitate the movement of nitrate ions from the concentrate to the distillate. This produces a dialysate having a NO3 / U molar ratio within specification for uranium nitrate lacking in acid and a recycled nitric acid stream.
[0022] The dialysate is fed to the product evaporation system where excess water is boiled off to produce a concentrate that is uranium nitrate lacking in acid at an acceptable concentration.
[0023] The recycled nitric acid stream is fed to the recovery evaporation system where excess water is boiled off to produce a concentrated nitric acid suitable for reuse in other processes.
[0024] Figure 1 shows one embodiment of a feedstock evaporation system. In some implementations, the system for producing oxygen-deficient uranyl nitrate from a dilute uranyl nitrate solution includes a check valve 10 configured to receive the feedstock solution and prevent the feedstock solution from flowing back into the original container that supplied the feedstock solution.
[0025] The operating valve 20 is controlled by a level sensor 50. The operating valve 20 is configured to receive the feedstock solution from the check valve 10 and supply the feedstock solution to the boiler 30 until the level sensor 50 closes the operating valve. In some implementations, when the level of the feedstock solution in the packed column 60 reaches a predetermined level on the level sensor 50, the level sensor 50 closes the operating valve 20.
[0026] In some implementations, the boiler 30 may be a shell-and-tube heat exchanger or a column with an immersion heater. In the case of a shell-and-tube heat exchanger, the feed material solution flows into the shell side of the boiler 30, where it is heated by a heat transfer medium flowing countercurrently through the tube side of the boiler 30. The heat transfer medium may be steam or hot oil at a temperature hot enough to induce boiling in the feed material solution.
[0027] If the boiler 30 is a column with an immersion heater, the feed material solution fills the column, and the level of the feed material solution is controlled so that the heating element is always immersed.
[0028] In some implementations, the boiler 30 is circulated either by a thermal siphon effect or by an attached forced circulation pump that draws the feedstock solution from the bottom of the boiler 30 and discharges it at the top of the boiler 30. The concentrate remains in the boiler 30 until it reaches the desired concentration, at which point it is discharged from the bottom of the boiler 30 by a concentrate transfer pump 40. In a steady state, a small flow of the feedstock solution is constantly entering and leaving the boiler 30 so that the volume in the boiler 30 remains constant.
[0029] Steam exits the boiler 30 and rises into the packed column 60. In some implementations, the packed column 60 is filled with packing material such as Raschig rings or wire mesh, which allows for more steam / liquid contact and improves separation efficiency. The separated steam is water containing only trace amounts of nitric acid and uranyl nitrate, and is drawn out of the packed column by a venturi 70. The venturi forms the first part of the steam scrubbing section of the system.
[0030] In some implementations, the scrubber section of the system may include a scrubber reservoir 90, which is initially filled with fresh deionized water via an operating valve 130. The scrubber solution is pumped by a pump 100 through a shell-and-tube heat exchanger 80 and back to the scrubber reservoir 90. A level switch 140 controls the level of the scrubber solution in the scrubber reservoir 90. For example, if the level of the scrubber solution in the scrubber reservoir 90 becomes too low, the operating valve 130 is opened to fill it. Alternatively, if the level of the scrubber solution in the scrubber reservoir 90 becomes too high, the level switch 140 activates a valve 110, which opens and discharges some amount of scrubber solution. In some implementations, the scrubber shell-and-tube heat exchanger 80 is connected to cooling water flowing through the tubular side.
[0031] The vapor that does not condense in the scrubber reservoir 90 passes through a mist eliminator 120 that captures any droplets that may have formed. The vapor then passes through a duct heater 150 that ensures the vapor remains hot enough not to condense in the ventilation system. Finally, the heated vapor is discharged, where it can enter the atmosphere as clean water vapor.
[0032] In some implementations, all vessels in this system have an outer diameter of 5.56 inches or less (≤5.56 inches) to maintain criticality control.
[0033] Figures 2A-2C show one configuration of the diffusion dialysis system. Referring to Figure 2A, concentrates from the feedstock evaporator system, such as the feedstock evaporator system described above in Figure 1, are supplied to the concentrate reservoir 160. Furthermore, distillates captured from the feedstock evaporator system, such as the feedstock evaporator system described above in Figure 1, are supplied to the distillate reservoir 170.
[0034] Pumps 180 and 190 are positioned at the discharge port of the membrane vessel 200 to control the flow through the membrane 200. The concentrate flows from the concentrate reservoir 160 through valve 130 through one side of the membrane vessel 200, while the distillate flows countercurrently from the distillate reservoir 170 through valve 130 through the opposite side of the membrane vessel 200. The membrane vessel 200 contains a helically wound anion membrane that divides the vessel into channels.
[0035] Figure 2B illustrates the processes occurring at the membrane interface within each membrane vessel 200. As shown in Figure 2B, within each membrane vessel, the feed material flow is separated from the deionized water flow by an anion membrane. This membrane allows nitrate ions to pass through, but prevents uranium ions from passing through. Nitrate ions are attracted to the negatively charged membrane and diffuse across the membrane into the clean water flow. The majority of uranium ions are retained in the feed material flow.
[0036] In some implementations of the diffusion dialysis system, multiple cells are stacked in series so that the above process continues through a series-connected membrane vessel 200. As the feed material flow flows down the stack of cells, the feed material flow becomes rich in metals and poor in acid. Furthermore, as the water flow flows down the stack of cells, the water flow becomes rich in acid and has little uranium contamination. In some implementations, the stack of membrane vessels is optimized to produce dialysate with a nitrate / uranium molar ratio of less than 1.7 (<1.7). The two outputs of this process are dialysate and recycled acid.
[0037] Referring to Figure 2C, the concentrated uranyl nitrate solution enters the process from the right side, and the distilled water product enters from the left side. The two flows countercurrently from stage to stage within the diffusion dialysis system. The concentrated uranyl nitrate solution exits the process on the left side as dialysate after the acid has been depleted. The distilled water product exits on the right side as recycled acid after the acid has been loaded. The concentration gradient in the countercurrent process remains relatively constant from stage to stage. For example, the concentrated uranyl nitrate solution enters stage A N+1 The acid is loaded, and water is added to stage O N It will be loaded.
[0038] Figure 3 shows one configuration of the product evaporation system. In some implementations, the product evaporation system in Figure 3 receives a dialysate flow from a diffusion dialysis system, such as the diffusion dialysis system described above in Figures 2A-2C, and concentrates the dialysate flow.
[0039] The product evaporation system in Figure 3 can operate similarly to the feedstock evaporation system described above, related to Figure 1. However, one difference is that a vacuum is provided by the vacuum pump 270, and all of the distillate is discharged as steam after passing through the reheater 280.
[0040] The output of the product evaporation system shown in Figure 3 by pump 240 is oxygen-deficient uranyl nitrate, which can be used in fuel production.
[0041] Figure 4 shows one configuration of the recovery evaporation system. In some implementations, the recovery evaporation system in Figure 4 receives a recycled acid stream from a diffusion dialysis system, such as the diffusion dialysis system described above in Figures 2A-2C, and concentrates the recycled acid stream.
[0042] The recovery evaporation system in Figure 4 can operate similarly to the product evaporation system described above in relation to Figure 3. The output of the recovery evaporation system is a recycled acid stream that can be used for fuel production.
[0043] Figure 5 shows one configuration of the overall system for producing oxygen-deficient uranyl nitrate from a dilute uranyl nitrate solution. As discussed above in relation to Figure 1, the feed material evaporation system 502 receives the feed material solution and produces distillate logistics 504 and concentrated logistics 506.
[0044] The diffusion dialysis system 508 receives the distillate material 504 and the concentrated material 506. As discussed above in relation to Figures 2A-2C, the diffusion dialysis system 506 flows the distillate material 504 in a first direction and the concentrated material 506 in a second opposite direction on the opposite side of the multiple anion membranes to facilitate the transfer of nitrate ions from the concentrated material to the distillate material.
[0045] When the distillate flow 504 and concentrated flow 506 are processed in this manner, the diffusion dialysis system 508 generates a dialysate flow 510 and a recycled acid flow 512.
[0046] The product evaporation system 514 receives the dialysate flow 510. As discussed above in relation to Figure 3, the product evaporation system 514 processes the dialysate flow 510 to provide oxygen-deficient uranyl nitrate 516 and gaseous emissions (water vapor) 518.
[0047] The recovery evaporation system 520 receives the recycled acid stream 512. As discussed above in relation to Figure 4, the recovery evaporation system 520 processes the recycled acid stream 512 to provide recycled acid 522 and gaseous emissions (water vapor) 524.
[0048] A system and method for producing oxygen-deficient uranyl nitrate from a dilute uranyl nitrate solution is described above in relation to Figures 1-5. While specific implementations of the disclosure are described herein, it will be apparent to those skilled in the art to which this disclosure relates that variations and modifications of the various implementations shown and described herein can be made without departing from the spirit and scope of the disclosure.
Claims
1. A feedstock evaporation system configured to receive a feedstock stream and remove water from the feedstock stream by boiling under vacuum to produce a concentrated uranyl nitrate solution and distilled water products; and A diffusion dialysis system configured to receive concentrated uranyl nitrate solution and distilled water products; to counterflow the concentrated uranyl nitrate solution and distilled water products to the opposite side of multiple membrane vessels to facilitate the transfer of nitrate ions from the concentrated uranyl nitrate solution to distilled water; and to generate dialysate flow and recycled acid flow. A system that includes this.
2. The system according to claim 1, wherein the feedstock stream includes the products of a solvent extraction process used to recycle spent nuclear fuel.
3. The system according to claim 1, wherein the supply material flow includes a recovery flow from fuel manufacturing activities other than solvent extraction processes used to recycle spent nuclear fuel.
4. The system according to claim 1, wherein multiple membrane vessels are connected in series.
5. The system according to claim 1, wherein each membrane vessel includes an anion membrane, the anion membrane being configured to allow nitrate ions to pass through the anion membrane and to prevent uranium ions from passing through the anion membrane.
6. The system according to claim 1, wherein multiple membrane vessels are configured to generate a dialysate flow having a nitrate / uranium molar ratio of less than 1.
7.
7. A product evaporation system configured to receive the dialysate flow from a diffusion dialysis system and concentrate the dialysate flow. The system according to claim 1, further comprising:
8. A recovery evaporation system configured to receive recycled acid flow from a diffusion dialysis system and concentrate the recycled acid flow. The system according to claim 1, further comprising:
9. In a feedstock evaporation system, the steps include: boiling and removing water from the feedstock stream under vacuum to produce a concentrated uranyl nitrate solution and a distilled water product; and In a diffusion dialysis system, the concentrated uranyl nitrate solution and the distilled water product are directed in the opposite direction of multiple membrane vessels to promote the transfer of nitrate ions from the concentrated uranyl nitrate solution to the distilled water, thereby generating a dialysate flow and a recycled acid flow. Methods that include...
10. The method according to claim 9, wherein the feedstock stream includes the product of a solvent extraction process used to recycle spent nuclear fuel.
11. The method according to claim 9, wherein the supply material stream includes a recovery stream from fuel manufacturing activities other than solvent extraction processes used to recycle spent nuclear fuel.
12. The method according to claim 9, wherein the membrane containers of a plurality of membrane containers are connected in series.
13. The method according to claim 9, wherein each membrane vessel includes an anion membrane, the anion membrane being configured to allow nitrate ions to pass through the anion membrane and to prevent uranium ions from passing through the anion membrane.
14. The method according to claim 9, wherein multiple membrane vessels are configured to generate a dialysate flow having a nitrate / uranium molar ratio of less than 1.
7.
15. In the product evaporation system, a step of concentrating the dialysate flow. The method according to claim 9, further comprising:
16. In a recovery evaporation system, a step of concentrating the recycled acid stream. The method according to claim 9, further comprising: