Improvements in tritium extraction and recovery and related improvements in fusion power systems

Abstract

An apparatus (100) and method for integrated tritium extraction and recovery in a fusion power system are described. The technique involves combining a flowable tritium breeding composition (120) with a second fluid (122)—in a tritium extraction unit (102)—to produce a combined fluid (110) flowing in two-phase flow, and extracting tritium from the breeding composition in the two-phase flow by a simultaneous process of permeation through a solid membrane (118) and tritium transfer to the second fluid (i.e., gas-liquid or liquid-liquid contact). A corresponding fusion power system is also described.

Description

[Technical Field]

[0001] The present disclosure relates generally to tritium breeding in fusion power systems. More specifically, the present disclosure relates to an improved tritium extraction and recovery system / apparatus "TERS" for use with liquid breeder materials. [Background technology]

[0002] Currently, magnetic confinement fusion reactors, primarily those designed around the tokamak principle, use fusion fuel containing a mixture of deuterium and tritium (i.e., hydrogen isotopes). While deuterium is readily available, for example, by extraction from seawater, natural tritium is extremely rare; current estimates place the amount of tritium on Earth at only 20 kilograms (kg), currently priced at approximately $30,000 per gram. DEMO, the demonstration power plant planned for ITER (described later), is estimated to require 300 grams of tritium per day for continuous power generation. STEP, a spherical tokamak for energy production, is similarly estimated to require several hundred grams per day for continuous operation. Therefore, it is desirable to discover a technology to produce tritium for use in fusion reactors.

[0003] Interestingly, tritium can be produced from the reaction of neutrons with lithium. Naturally, neutrons are produced by fusion reactors, so one technique for producing tritium is to coat the reactor with a lithium blanket. Naturally, this raises the question of how to recover the tritium being produced in the blanket for use in the reactor. One approach to tritium extraction is permeation against vacuum (PAV), which allows tritium to exit the fluid by migrating through a hydrogen-permeable membrane into a vacuum tube. Another approach is by gas-liquid contactor (GLC), which separates tritium from the liquid breeder by directly contacting the liquid breeder with a gas; tritium is transferred to the gas phase due to the formation of a concentration gradient. Neither approach is particularly efficient; for example, PAV efficiencies typically between 5 and 39% are reported, with more recent PAV designs reporting tritium recovery efficiencies of up to 80%.

[0004] In particular, increased recovery efficiency and a smaller TERS footprint are desired, as this would allow for a reduction in tritium inventory and bound intratubular components (IVCs) within the breeder blanket. Therefore, it is desirable to develop improved and / or alternative techniques for tritium breeding with improved recovery efficiency to provide fuel for fusion systems. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention is defined by the independent claims. Additional features will be recognized from the dependent claims and the description herein. Any embodiments that are described but do not fall within the scope of the claims should be interpreted only as examples useful for a better understanding of the invention.

[0006] The illustrative embodiments are provided with a view to addressing at least some of the difficulties faced by current approaches to tritium extraction and recovery, whether or not those difficulties are specifically mentioned above or otherwise recognized from the discussion herein.

[0007] Broadly, the present technology aims to provide an integrated process in which tritium extraction is achieved by permeation and by gas-liquid (or liquid-liquid) catalytic separation. Advantages of the integrated contactor-permeator described herein include improved efficiency of tritium recovery and reduced tritium residence time within the system, thereby allowing for smaller equipment, lower tritium inventory, and compatibility with conventional breeder systems, including manufacturing, equipment, and maintenance considerations similar to conventional PAV systems, thereby reducing the risks associated with the implementation of this technology. [Means for solving the problem]

[0008] Thus, in one aspect of the present invention, an apparatus for use in tritium extraction and recovery in a fusion power system is provided. The apparatus comprises a manifold configured to receive first and second fluids of a tritium breeding composition and discharge a combined fluid flowing in a two-phase flow, the breeding composition forming the carrier phase of the two-phase flow while the second fluid forms the other phase. The apparatus further comprises a tritium extraction unit configured to receive the combined fluid and extract tritium from the breeding composition in a two-phase flow by a combination of processes: (i) a process of tritium permeation through a hydrogen-permeable solid boundary / membrane and simultaneously (ii) a process of tritium transfer to the second fluid (i.e., gas-liquid or liquid-liquid contact). Two-phase flow offers the dual benefit of enabling the deployment of two different extraction mechanisms within the same apparatus while also enhancing the permeation performance of tritium extraction.

[0009] Preferably, the second fluid (such as an inert gas or molten salt) has a higher tritium affinity than the first fluid. In particular, the choice of the second fluid may vary according to the choice of the breeding composition. For example, the tritium breeding composition may be formed from pure liquid lithium, and preferably the second fluid may be a molten salt such as lithium chloride; the tritium breeding composition may be formed from a lithium-based molten salt such as lead-lithium liquid metal (PbLi) or FLiBe (a mixture of lithium fluoride (LiF) and beryllium fluoride (BeF2)), and the second fluid may comprise an inert gas, preferably helium.

[0010] In one example, the tritium extraction unit is configured to include a first flow path, a second flow path, and a hydrogen-permeable membrane therebetween (i.e., connecting the first and second flow paths). The first flow path is configured to receive the combined fluid flowing in two-phase flow, while the second flow path is configured to receive tritium from the first flow path via the hydrogen-permeable membrane, and the second flow path may be under vacuum pressure or may include a flow of sweep gas. In some examples, the tritium extraction unit includes a third flow path positioned on the opposite side of the second flow path from the first flow path and separated from (and connected to) the second flow path by a hydrogen-permeable membrane, and the third flow path is also configured to receive the combined fluid of the growth composition and the second fluid flowing in two-phase flow. Preferably, the flow paths are formed in a planar arrangement and may be positioned horizontally with the ground when the unit is in use.

[0011] In another aspect of the present invention, a fusion power system is provided. The system includes a vacuum tube and a tritium breeding blanket (at least partially) covering the inner or outer wall of the plasma vacuum tube, the tritium breeding blanket being filled with a flowable tritium breeding composition (such as pure lithium, or PbLi, or FLiBe). The system also includes a tritium extraction and recovery device including a manifold configured to receive the flowable tritium breeding composition and a second fluid to deliver a combined fluid flowing in two-phase flow, and a tritium extraction unit configured to receive the combined fluid and extract tritium from the breeding composition by a combination of tritium permeation through a hydrogen-permeable solid boundary / membrane and simultaneous tritium transfer to the second fluid. Such a system may include other suitable components, such as a tritium storage unit.

[0012] Suitably, in another aspect of the present invention, there is provided a method for tritium extraction from a flowable tritium breeding composition, said method comprising combining the tritium breeding composition with a second fluid to produce a combined fluid flowing in two-phase flow, and extracting tritium from the breeding composition in the two-phase flow by a simultaneous process of permeation through a hydrogen-permeable solid boundary / membrane and transfer of tritium to the second fluid (i.e., gas-liquid contact).

[0013] For a better understanding of the present disclosure, reference will now be made, by way of example only, to the accompanying drawings in which: [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 shows a schematic diagram of the fusion power system process, including an example of the tritium extraction and recovery process. [Figure 2] FIG. 2 shows an example of the vacuum infiltration process. [Figure 3] FIG. 3 shows a process schematic of an exemplary improved tritium extraction and recovery system. [Figure 4] FIG. 4 shows an example of a tritium extraction unit for use in an example tritium extraction and recovery system. [Figure 5] FIG. 5 shows an example of two-phase flow and the associated tritium distribution. [Figure 6] FIG. 6 shows a further example of two-phase flow. DETAILED DESCRIPTION OF THE INVENTION

[0015] At least some of the following example embodiments provide improved techniques for tritium extraction and recovery. Other advantages and improvements will be apparent from the embodiments discussed herein.

[0016] FIG. 1 shows a simplified process schematic of a prior art breeder system. Here, the reactor 10 uses deuterium and tritium as fusion fuel, and their reaction produces neutrons. The fusion reaction occurs in the reactor vacuum tube 11, with neutrons penetrating the wall of the vacuum tube 11 and entering the breeder blanket 24. A fluid containing tritium / tritiated species (either in the form of a coolant or breeder liquid) is pumped from the blanket 24 so that tritium can be extracted by a suitable tritium extraction and recovery system 16. The extraction and recovery system 16 includes a unit for extracting tritium from the breeder fluid, either a vacuum permeation unit 30 or a gas-liquid contactor 32, and a method for conditioning and storage of tritium 34. After some time, the recovered tritium is circulated from the storage device 34 to the reactor by a suitable material injection system 18.

[0017] By way of example, Figure 2 shows an example of a conventional permeator against vacuum "PAV" unit 30. The unit 30 includes a flow path carrying tritium-rich liquid breeder (e.g., lithium lead, LiPb) (originating from the breeder blanket 24) and a vacuum flow path separated from the liquid breeder by a membrane through which tritium can pass. Breeder liquid entering the left-hand side of the PAV in Figure 2 becomes depleted in tritium as it passes from left to right and tritium permeates the vacuum flow path. The liquid breeder, now with a low concentration of tritium, is pumped back to the breeder blanket 24 to once again breed tritium from neutron interactions.

[0018] 3 shows a process schematic of an improved technique for tritium extraction and recovery in a fusion power system, in which an example of an improved tritium extraction and recovery apparatus (or system) 100 is used. In particular, apparatus 100 includes a tritium extraction unit 102 configured to perform tritium extraction on a breeder material composition supplied to unit 102 by permeation and simultaneous gas-liquid (or liquid-liquid) contacting processes. That is, to extract tritium from the breeder composition, the tritium extraction unit uses tritium permeation through a solid, while a concentration gradient is formed between the breeder material composition and a second fluid, promoting tritium transfer to the second fluid phase, similar to known PAVs.

[0019] Apparatus 100 suitably comprises a manifold 104 that supplies fluid to tritium extraction unit 102. More specifically, manifold 104 is configured to receive a first fluid of a tritium breeding composition from breeding blanket 24 and also to receive a second fluid from, for example, reservoir 106 (although it will be appreciated that the exact source of the second fluid may vary). The tritium breeding composition may be at least one of a lithium-based salt, a lithium-based liquid metal, or a lithium-based alloy, while the second fluid may be at least one of an inert gas or a lithium-based salt (which is also not the first fluid).

[0020] Manifold 104 is configured to combine the two fluids into a two-phase flow in which the first fluid / growth material composition forms the carrier phase and the second fluid forms the other, second phase. In the example shown, the manifold is configured to combine the fluids prior to delivery to tritium extraction unit 102 for initial tritium extraction. However (not shown), in other examples, the manifold may be located within tritium extraction unit 102 (in such case, the description of tritium extraction unit 102 below thereby applies to the portion of tritium extraction unit 102 after manifold 104).

[0021] As the composite fluid progresses through the tritium extraction unit 102, at least some of the tritium is extracted from the first phase (i.e., the breeder composition) by a permeation process and suitably recovered, in this example, by sending to the conditioning and storage unit 34. At least some of the tritium is also extracted from the first phase / breeder composition by migration onto the second-phase fluid and suitably recovered after the two-phase fluid exits the tritium extraction unit 102 and after separating the composite fluid back into two separate fluids. That is, the separated fluid breeder composition is returned to the breeder blanket 24 for tritium production (i.e., closing the breeder fluid circulation), while the separated (tritium-rich) second fluid is sent to further processes to recover tritium for subsequent use. The particular means for separating the growth composition from the second fluid and then recovering tritium from the second fluid will be readily recognized by those skilled in the art of gas-liquid contacting, but for example, recovery of tritium from the second fluid may be incorporated as part of the conditioning and storage unit 34.

[0022] It will also be appreciated that in some example arrangements, extracted tritium may not require storage and may instead be suitably delivered directly back to the reactor, for example, by material injection system 18. Similarly, it is not necessary for tritium extracted by permeation and tritium extracted from the second fluid to follow the same optimal route to storage / reactor (although this is preferred for simplicity of construction and maintenance, etc.); for example, tritium extracted by permeation may be suitable for recycling directly to reactor 10, while tritium extracted by transfer to the second fluid may be more suitable for storage.

[0023] 4 shows a more detailed example of a tritium extraction unit 102. The tritium extraction unit 102 comprises a first flow path 108 arranged to receive a composite fluid 110 flowing in a two-phase flow, exemplified here by a fluid that is primarily a tritium growth composition 120 interspersed with bubbles of a second fluid 122, such as helium (although other inert gases, such as argon, can also be used as the second fluid). The flow path 108 conveys the composite fluid 110 from a first end 112 of the unit 102 to a second end 114 of the unit 102; that is, the first end 112 may be considered the fluid inlet side of the unit 102, and the second end 114 may be considered the fluid outlet side of the unit 102. In this example, the composite fluid 110 flows from left to right, from the inlet 112 to the outlet 114, and may be induced to do so by an appropriately configured pump, although other means of moving the composite fluid 110 through the apparatus 100 may also be employed.

[0024] The tritium extraction unit 102 also includes a second flow path 116 separated from the first flow path 108 by a hydrogen-permeable membrane 118. The material of the hydrogen-permeable membrane 118 is appropriately chosen for a combination of bulk strength (to retain the first fluid within the flow path 108 and to support the structure of the tritium extraction unit 102) and tritium permeability. However, it will be recognized that while the first flow path 108, the second flow path 116, and the hydrogen-permeable membrane 118 are described herein as separate, in fact the flow paths may be considered to be formed at least in part (or entirely) from the hydrogen-permeable membrane—i.e., the membrane 118 may be considered to form at least a portion of a superstructure, or the body, for the tritium extraction unit 102 defining the corresponding flow path therein.

[0025] Suitably, second flow path 116 is provided to receive tritium permeating through membrane 118 from first flow path. Thus, at inlet 112, tritium-rich (i.e., coming directly from breeder blanket 24) tritium breeding composition 120 is at least partially depleted of tritium as it passes through tritium extraction unit 102. However, some tritium is absorbed by second fluid bubbles 122. Therefore, the composite fluid exiting tritium extraction unit 102 may be considered to be formed from a tritium breeder composition containing a low concentration of tritium and a helium-tritium gas combination (which may be recognized by those skilled in the art as being highly suitable for subsequent tritium extraction by an appropriate separation process). For this reason, it is preferable (but not essential) for second fluid 122 to have a higher tritium affinity than breeder composition 120. In particular, the tritium breeding composition 120 may be formed from pure liquid lithium and the second fluid may be a molten salt (such as lithium chloride, chlorides of lithium and sodium or potassium mixtures, or lithium carbonate), while the tritium breeding composition 120 may be formed from lead-lithium or FLiBe and the second fluid may be an inert gas such as helium.

[0026] Two-phase flow not only allows the deployment of two different extraction mechanisms in the same device 100, but also has performance benefits in terms of the permeability of the tritium extraction unit 102.

[0027] Figure 5 demonstrates these benefits for the case of idealized Taylor (two-phase) flow in the first flow channel 108. Figure 5A shows the fluid behavior of the tritiated breeder composition 120 and helium bubbles 122, Figure 5B shows the tritium distribution in the flow channel with single-phase flow, and Figure 5C shows the tritium distribution for the example of Figure 5A.

[0028] In a single-phase flow of breeder material composition, the extracted tritium, even if substantially uniform, may be scattered randomly throughout the cross section of the fluid. Tritium close to the hydrogen-permeable membrane 118 may permeate very quickly due to its proximity, while the bulk of the tritium toward the center of the channel 108 may take a very long time to progress down the concentration gradient. Hence, the tritium concentration follows a distribution (FIG. 5B) with more tritium in the center of the channel at any given time.

[0029] In contrast, in the case of two-phase flow, bubbles 122 help create a thin film of breeder composition 120 along a section (e.g., section 124) that brings tritium closer to membrane 118 and thus more readily permeates through the boundary. Also, the fluid behavior between carrier (breeder) fluid 120 and bubbles 122 alters the flow pattern sufficiently that tritium begins to stagnate away from the axis of the flow path and very close to the side surface (i.e., the permeation membrane), so that the tritium concentration profile may instead look like Figure 5C. Therefore, the rate of tritium permeation from composition 120 is increased even during the simultaneous formation of bubbles 122.

[0030] While Figure 5 shows a preferred example of two-phase flow, similar benefits may be realized (to generally a lesser extent) from other forms of two-phase flow, such as those shown in Figure 6. In other words, while it is preferred that the manifold and flow parameters of the first / second fluid inputs be configured to produce Taylor flow, this is not essential.

[0031] Returning to FIG. 4 , in one example, the second flow path 116 is maintained at a vacuum (negative) pressure to provide a flow direction for tritium permeating the flow path; here, the direction is shown as right to left, but the direction is not critical and its selection will depend on the physical system considerations for its use. In this way, the system 100 can be more readily used as a replacement for fusion systems currently using known PAV technology (which then already have an appropriate vacuum system ready to be coupled to the tritium extraction unit 102). As another example, the second flow path 116 is at least partially filled with a sweep gas, such as helium, whose flow assists in flowing tritium through and out of the tritium extraction unit 102, where it can be separated from the sweep gas. The benefit of using a sweep gas is that helium (or other) gas compressors and corresponding piping are generally cheaper to purchase, install, and operate compared to vacuum systems. In either case, tritium permeating the second flow path can be appropriately recovered. In some instances, the sweep gas contains a very small amount of an additive such as oxygen to aid in the subsequent release of tritium from the film surface.

[0032] As shown, in this example, the first flow path 108 and the second flow path 116 are configured to run parallel to one another substantially along the length (x-direction, left / right) of the tritium extraction unit 102. Similarly, the hydrogen permeable membrane 118 provides a shared boundary between the first flow path 108 and the second flow path 116 substantially along the entire length of the tritium extraction unit 102. Such an arrangement provides an increased surface area in the first flow path 108 through which tritium can permeate out of the fluid.

[0033] Moving to three dimensions, more generally, the first flow path 108 and the second flow path 116 are preferably provided in a planar arrangement. That is, the first and second flow paths each define parallel planes in the x (left / right) and y (into / out of the page) directions. Furthermore, this parallel planar arrangement provides a larger surface area for tritium permeation. Furthermore, the tritium extraction unit 102 in this arrangement should preferably be installed horizontally to the ground (i.e., perpendicular to the direction of gravity) to avoid any unnecessary fluid pumping load that might otherwise occur, for example, due to gravity acting on the fluid 110.

[0034] Continuing with the current example, tritium extraction unit 102 may be considered to comprise a third flow path 126 disposed on the opposite side of second flow path 116 to first flow path 108, the second and third flow paths being similarly separated by hydrogen-permeable membrane 118. The third flow path also receives combined fluid 112, thus in this arrangement providing even more surface area for tritium to permeate through hydrogen-permeable membrane 118 into second flow path 116. Suitably, manifold 104 may be adapted to supply combined fluid to both the first and third flow paths, or separate manifolds may be provided in which each flow path is supplied with the combined fluid.

[0035] In some examples, this principle may be further carried forward with the tritium extraction unit 102 configured with a stacked arrangement combining alternate tritium extraction and fluid-carrying channels. That is, a fourth channel may be configured adjacent to the third channel on the opposite side of the second channel, a fifth channel may be configured adjacent to the fourth channel on the opposite side of the third channel, and so on, each of the channels essentially adjacent but separated by a hydrogen-permeable membrane, with odd-numbered channels combined with fluid-carrying channels and even-numbered channels combined with tritium extraction channels. Or, in other words, the first and second channels 108, 116 may be considered to define a single stack design in a stacked arrangement, with multiple stacks formed from pairs of first and second channels being located atop the third channel 126, which in this case may be considered the bottom or foundation channel of the tritium extraction unit 102. Also, while the above description assumes that the composite fluid-carrying channels will be the outermost channels of the stack (i.e., top and bottom), it will be appreciated that the above arrangement can be modified to have the tritium extraction channel as the outermost channel while still achieving substantially the same functionality.

[0036] The dimensions of the first, second, and possibly third flow paths 108, 116, 126 may be determined based on the desired flow rates of the fluids / gases passing through the different paths. For example, with respect to the integration of the current device with the breeder blanket designed for the DEMO power plant, the width of the first / third flow path 108 (or each such flow path in the stack) was determined to be between 0.5 centimeters (cm) and 2 cm in the z-direction, producing particularly advantageous two-phase flow. Simulations also indicated that tritium extraction efficiencies of over 80% (i.e., greater than previously achieved efficiencies) could be achieved with flow path lengths of around 5 meters (m), much shorter than many other PAV systems, thereby reducing the overall profile of the required equipment and the corresponding space required for the power plant. In some instances, simulations indicated efficiencies between 85% and 95% with properly optimized devices.

[0037] In summary, an exemplary embodiment of an improved apparatus for tritium extraction and recovery has been described. The apparatus includes a manifold and a tritium extraction unit. The manifold is configured to combine a tritium breeding composition with a second fluid to produce a combined fluid flowing in two-phase flow. The tritium extraction unit receives the combined fluid for simultaneous extraction of tritium from the breeding composition by tritium permeation through a solid membrane and tritium transfer to the second fluid.

[0038] The described exemplary embodiments enable more efficient and improved fusion power technology, facilitating continuous reactor operation: a key consideration for commercial energy production. Additionally, the exemplary embodiments reduce the energy demand for tritium production associated with existing breeder blankets, allowing for the reduction of on-site tritium inventories.

[0039] The example devices may be manufactured industrially. Industrial applications of the example embodiments will become apparent from the discussion herein. Additionally, the exemplary embodiments described are affordable to manufacture and simple to use.

[0040] While preferred embodiments of the present invention have been shown and described, it will be recognized by those skilled in the art that modifications may be made without departing from the scope of the invention as defined in the claims and the above description. For example, although repeated references herein have been made to fluid channels, it will be recognized by those skilled in the art that a fluid channel extends to other forms of (closed) fluid pathways such as pipes, conduits, etc., and does not extend to providing specific geometric configurations except as set forth in specific examples.

[0041] Attention is drawn to all papers and documents related to this application that are filed contemporaneously with or prior to this specification and that are open to public inspection herewith, and the contents of all such papers and documents are incorporated herein by reference.

[0042] All features disclosed in this specification, and / or all steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0043] Each feature disclosed in this specification, unless expressly stated otherwise, may be replaced by alternative features serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is one example, but not limited to, of a generic series of equivalent or similar features.

[0044] The invention is not limited to the details of the foregoing embodiments, but extends to any novel feature or combination of features disclosed in this specification, or to any novel step or combination of any method or process steps so disclosed. [Explanation of symbols]

[0045] 10 furnace 11 Vacuum tube 16 Tritium Extraction and Recovery System 18 Material Injection System 24 Breeding Blanket 30 Infiltration Unit 34 Storage Unit 100 Recovery Device 102 Tritium Extraction Unit 104 Manifold 106 Reservoir 108 First Channel 110 Complex fluid 112 Entrance 114 Exit 116 Second Channel 118 Hydrogen permeable membrane 120 Tritium Breeding Material Composition 122 Second fluid 124 sections 126 Third Channel

Claims

1. 1. An apparatus for use in tritium extraction and recovery in a fusion power system, comprising: a manifold configured to receive a first fluid and a second fluid comprising a tritium breeding composition and to discharge a composite fluid flowing in a two-phase flow, the first fluid being a first, carrying, phase of the two-phase flow and the second fluid being a second phase of the two-phase flow; a tritium extraction unit configured to receive the composite fluid and extract tritium from the tritium breeding composition by a combination of tritium permeation through a hydrogen permeable membrane and tritium transfer to the second fluid; An apparatus comprising:

2. The apparatus of claim 1 , wherein the second fluid comprises at least one of an inert gas and a molten salt.

3. 3. The apparatus of claim 1, wherein the second fluid has a higher affinity for tritium than the first fluid.

4. 4. The apparatus of claims 2 and 3, wherein the tritium breeding composition is formed from pure liquid lithium and the second fluid comprises the molten salt.

5. 5. The apparatus of claim 4, wherein the molten salt comprises at least one of lithium chloride, lithium sodium chloride, lithium potassium chloride, or lithium carbonate, or a combination thereof.

6. 4. The apparatus of claims 2 and 3, wherein the tritium breeding composition is formed from a lithium-based molten salt or a lithium-based eutectic alloy, and the second fluid comprises the inert gas, e.g., helium.

7. 7. The apparatus of claim 6, wherein the lithium-based molten salt is one of PbLi or FLiBe.

8. 8. The apparatus of claim 1, wherein the tritium extraction unit comprises a first flow path, a second flow path, and the hydrogen-permeable membrane therebetween, the first flow path being arranged to receive the composite fluid flowing in a two-phase flow, and the second flow path being arranged to receive tritium from the first flow path via the hydrogen-permeable membrane.

9. The device of claim 8 , wherein the first and second flow paths are planar in orientation.

10. The apparatus of claim 9 , wherein the planar arrangement is perpendicular to gravity.

11. 11. The apparatus of claim 8, wherein the tritium extraction unit comprises a third flow path disposed on an opposite side of the first flow path from the second flow path, and a second hydrogen-permeable membrane between the second and third flow paths, the third flow path also being disposed to receive the composite fluid flowing in a two-phase flow, and the second flow path also being disposed to receive tritium from the third flow path via the second hydrogen-permeable membrane.

12. An apparatus according to any preceding claim, wherein the second flow path carries a flow of a sweep gas.

13. The apparatus of claim 12 , wherein the sweep gas comprises helium.

14. 1. A fusion power system comprising: Vacuum tubes and a tritium breeder blanket at least partially covering the vacuum tube and comprising a flowable tritium breeding composition; a manifold configured to receive the flowable tritium breeding composition and a second fluid and to discharge a combined fluid flowing in a two-phase flow, the flowable tritium breeding composition being a first, carrying, phase of the two-phase flow and the second fluid being a second phase of the two-phase flow; a tritium extraction unit configured to receive the composite fluid flowing in two-phase flow and extract tritium from the breeding composition by a combination of tritium permeation through a hydrogen-permeable membrane and tritium transfer to the second fluid.

15. 1. A method for tritium extraction from a flowable tritium enrichment composition, comprising: combining the flowable tritium breeding composition with a second fluid to produce a combined fluid flowing in a two-phase flow, the flowable tritium breeding composition being a first, carrying, phase of the two-phase flow and the second fluid being a second phase of the two-phase flow; extracting at least some tritium from the growth composition in the two-phase flow by a process of tritium permeation through a hydrogen-permeable membrane and simultaneously extracting at least some tritium from the growth composition in the two-phase flow by a process of tritium transfer to the second fluid.

Images