Fusion vacuum vessel for mechanical radial insertion and thermally activated sector-to-sector vacuum seals

Abstract

A fusion power plant is described which includes a plurality of toroidal-shaped vacuum vessel (VV) segments for use in a liquid immersion blanket. The fusion power plant also includes flanges of inter-coil ports having metal alloys compatible with the fusion environment. Poloidally continuous thin gaskets separate the VV sections. The gaskets are situated at the mating surface interface of one toroidal section to its toroidal neighbor and the gaskets are configured so that the VV sections do not make direct mechanical contact with each other. The gaskets provide electrical isolation of the VV sections, corrosion resistance to the blanket fluid, and intermetallic formation. The gasket is composed of a material that has a melting temperature higher than the operating temperature of the fusion power plant. A thin layer is disposed on the mating surfaces of the VV segments to prevent diffusion bonding and to further electrically insulate adjacent modules.

Description

[0001] FUSION VACUUM VESSEL FOR MECHANICAL RADIAL INSERTION AND

[0002] THERMALLY ACTIVATED SECTOR-TO-SECTOR VACUUM SEALS

[0003] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH Not Applicable.

[0004] CROSS-REFERENCE TO RELATED APPLICATIONS

[0005] This application is a U.S. Nonprovisional application which claims the benefit of U.S. Provisional Application No.: 63 / 647.585, filed May 14, 2024, which is hereby incorporated herein by reference in its entirety.

[0006] BACKGROUND:

[0007] Due to high neutron fluxes radiating from plasma of a power plant, vacuum vessels (VV) components of a fusion power plant are damaged by the neutron fluxes on timescales shorter than power plant lifetimes, necessitating replacement of the VV components at regular intervals. Existing VV replacement schemes are complex and feature lengthy assembly, welding, and weld breaking procedures that are performed in and around highly radioactive surfaces and materials. These schemes typically include deenergizing other components of the power plant to enable insertion of electronic devices used to perform the replacement.

[0008] What is needed are techniques that remove in-si tu physical interaction with the VV structure in order to create or break a vacuum seal, so replacement can be achieved without significant disruption of plant operation, enabling higher plant utilization ratios.

[0009] SUMMARY

[0010] The below summary’ is merely representative and non-limiting.

[0011] The above problems are overcome, and other advantages may be realized, by the use of the concepts and embodiments described herein. Various concepts and embodiments described herein provide components and techniques that eliminate in-situ physical interaction with the VV structure to create or break a vacuum seal. Replacement of the VV components can be achieved without significant disruption of plant operation, enabling higher plant utilization ratios. The concepts, systems, structures and techniques described herein are directed towards a method for installation, replacement and sealing of vacuum vessel (VV) sections in fusion power plants. The invention uses mechanical radial insertion of toroidal sections which then form vacuum seals via thermal expansion of vessel components as the components are brought to their operating temperature. The vacuum vessel (VV) is constructed of a plurality of VV sections appropriately shaped for a given plasma geometry. In embodiments, the VV sections are toroidal-shaped VV sections. In embodiments, the VV sections are appropriately shaped in poloidal directions for a given plasma geometry. The VV sections are structural attached to flanges of inter-coil ports. In embodiments, the VV sections are provided from a structural material (e.g., one or more metal alloys) compatible with a fusion environment. In an assembly process of one embodiment, adjacent VV sections are separated by a poloi dally continuous gaskets situated at a mating surface of one VV section. The gasket is comprised of a metal softer than the structural material of the VV sections, with a melting temperature higher than the operating temperature of the fusion device. Thus, in this way, VV sections do not make direct mechanical contact with each other, but only with the gasket. In embodiments, an insulating material is deposited on surfaces of structural material which are in contact with the gasket to provide both electrical isolation of the sections, corrosion resistance to the blanket fluid, and intermetallic formation. In embodiments, the insulating material may comprise or be provided as a layer of metal oxide disposed between the structural material of the VV sections and the gasket.

[0012] In a first aspect, an embodiment provides a fusion power plant. The fusion power plant includes a plurality of toroidal-shaped vacuum vessel (VV) sections in a liquid immersion blanket. The fusion power plant also includes flanges of inter-coil ports having metal alloys compatible with the fusion environment. Poloidally continuous thin gaskets separate the VV sections. The gaskets are situated at the mating surface interface of one toroidal section to its toroidal neighbor and are configured so that the VV sections do not make direct mechanical contact with each other. The gaskets are configured to provide electrical isolation of the VV sections, corrosion resistance to the blanket fluid, and intermetallic formation. The gasket is composed of a material (e.g., Ni) that has a melting temperature higher than the operating temperature of the VV. A thin layer (e.g., AI2O3) is disposed on the mating surfaces of the VV sections to prevent diffusion bonding and to further electrically insulate adjacent modules.

[0013] In a further embodiment of the fusion power plant above, the VV sections and the gaskets are fully extractable at room temperature.

[0014] In another embodiment of any one of the fusion power plants above, the VV sections and the gaskets are single-use components.

[0015] In a further embodiment of any one of the fusion power plants above, the VV sections are separated from each other by about 10 mm and form vacuum seals by thermal expansion during operation.

[0016] In another aspect, an embodiment provides a vacuum vessel (VV) segment for a fusion power device. The VV segment includes a first toroidal section body shaped in poloidal directions for a given plasma geometry. The first toroidal section body having a mating surface configured to interface with a second toroidal section body. The VV segment also includes at least one structural attachment point configured to secure the first toroidal section body for radial movement. A gasket is disposed on the mating surface. The gasket is a poloidally continuous thin gasket. The first toroidal section body and the at least one structural attachment point include a structural material compatible with a fusion environment of the fusion power device. The gasket includes a metal that is softer than the structural material.

[0017] In a further embodiment of the VV segment above, the first toroidal section body includes a metal that has a melting temperature higher than an operating temperature of the fusion power device.

[0018] In another embodiment of the VV segment above, the VV segment includes the second toroidal section body, wherein the gasket is disposed between the first toroidal section body and the second toroidal section body, the gasket is configured to prevent mechanical contact between the first toroidal section body and the second toroidal section body.

[0019] In a further embodiment of the VV segment above, the VV segment includes a thin layer of metal oxide deposited on the mating surface.

[0020] In another embodiment of the VV segment above, the first toroidal section body is configured to expand during fusion production by the fusion power device. The first toroidal section body may be configured to expand in at least one of: a toroidal direction, a poloidal direction and a radial direction. The first toroidal section body may be configured to compress the gasket to form a toroidally continuous vacuum seal with a neighboring toroidal section body during the fusion production by the fusion power device. The first toroidal section body can contract after fusion production by the fusion power device. The gasket may separate from the neighboring toroidal section body after the fusion production by the fusion power device and break the toroidally continuous vacuum seal.

[0021] In a further embodiment of the VV segment above, the VV segment includes a radial port flange configured to allow access to an interior of the first toroidal section body.

[0022] In another aspect, an embodiment provides a method for installing / replacing vacuum vessel (VV) segment in a fusion power device. The method includes attaching a VV segment to an installation arm and radially translating the VV segment between a pair of toroidal field coils of a fusion power device by moving the installation arm.

[0023] In a further embodiment of the method above, the method also includes disposing a gasket on a mating surface of the vacuum vessel segment. The mating surface is configured to interface with a second vacuum vessel segment. The vacuum vessel segment is heated, for example, by bringing the fusion power device to an operating temperature, causing the vacuum vessel segment to expand in toroidal, poloidal and radial directions and compress a gasket to form a toroidally continuous vacuum seal with a neighboring toroidal section body.

[0024] In another embodiment of the method above, attaching the vacuum vessel segment to an installation arm includes securing at least one structural attachment point of the installation arm to the vacuum vessel segment.

[0025] In a further embodiment of the method above, the method is performed while the fusion power device is generating high magnetic fields.

[0026] In another embodiment of the method above, attaching the vacuum vessel segment and inserting the vacuum vessel segment into a fusion blanket volume are done at room temperature.

[0027] In a further embodiment of the method above, the method is performed while the fusion power device is generating high magnetic fields.

[0028] In another embodiment of the method above, the method also includes heating the vacuum vessel segment to an operating temperature of the fusion power device. In a further embodiment of the method above, the method also includes depositing a thin layer of metal oxide on a mating surface of the vacuum vessel segment.

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The foregoing features may be more fully understood from the following description of the drawings in which various aspects of the concepts and embodiments described herein are described. It should be appreciated the figures are not necessarily drawn to scale. In the drawings, 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 drawing.

[0031] Figure 1 A is a perspective view of a portion of a fusion power plant in accordance with an embodiment.

[0032] Figure IB is top view of multiple vacuum vessel (VV) sections forming a single vacuum vessel in accordance with an embodiment.

[0033] Figure 2 is a perspective view- of a VV section fully inserted in a fusion power plant in accordance with an embodiment.

[0034] Figure 3 is a perspective view of a VV section fully extracted from a fusion power plant in accordance with an embodiment.

[0035] Figure 4 is a perspective view of a VV section attached to an extension device in accordance with an embodiment.

[0036] Figure 5A is an enlarged a perspective view of a VV section having a gasket disposed on a mating edge of a VV section in accordance with an embodiment.

[0037] Figure 5B is a block diagram illustrating a gasket and spacing between two VV sections in accordance with an embodiment.

[0038] Figure 5C is a perspective partial cross sectional view of two adjacent VV sections having a gasket therebetween in accordance with an embodiment.

[0039] Figure 5D is a perspective cut-away view of a VV section illustrating cooling channels in accordance with an embodiment.

[0040] Figure 5E is an enlarged perspective of a portion of the VV section of Figure 5D.

[0041] Figure 5F is a perspective view7of a VV section in accordance with another embodiment. Figure 6A is a perspective view of a gasket between two adjacent VV sections in accordance with an embodiment.

[0042] Figure 6B is an enlarged a perspective view of the gasket shown in Figure 6A.

[0043] Figure 7A is a plan view of multiple VV sections forming a single vacuum vessel in accordance with an embodiment.

[0044] Figure 7B is an enlarged plan view of a portion of the vacuum vessel of Figure 7A.

[0045] Figure 7C is a plan view illustrating spacing between two vacuum vessels at room temperature.

[0046] Figure 7D is a plan view illustrating spacing between two vacuum vessels of Figure 7A at operating temperature.

[0047] Figure 8 is a perspective view of a portion of two VV sections illustrating an alignment structure and gasket provided in the VV sections.

[0048] Figure 9 is an enlarged perspective view of a portion of the VV sections of Figure 8.

[0049] Figure 10 is a flow diagram that illustrates the operation of a method in accordance with various embodiments.

[0050] DETAILED DESCRIPTION

[0051] Various embodiments described herein provide a method for installation, replacement and sealing of vacuum vessel (VV) sections in fusion power plants. Embodiments described herein use mechanical radial insertion of VV sections which then form vacuum seals via thermal expansion of the vacuum vessel components (e.g., a VV gasket) as the vacuum vessel is brought to operating temperature.

[0052] Before describing details of the concepts, systems and techniques disclosed herein, it should be appreciated that reference is made herein to a tokamak fusion reactor having a toroidal-shaped vacuum vessel. Such reference is made only to promote clarity in the description of the broad concepts sought to be protected herein. It should be understood the concepts, systems, structures and techniques described herein may be used in connection with any type of fusion reactor including but not limited to a stellerator or any other type of magnetic confinement fusion device.

[0053] The vacuum vessel (VV) is constructed of a series of sections or segments appropriately shaped in the poloidal directions for a given plasma geometry. These sections and their structural attachments to the flanges of inter-coil ports are manufactured of metal alloys compatible with the fusion environment.

[0054] In an assembly process, adjacent sections are separated by a poloi dally continuous thin gasket situated at the mating surface interface of one section to its toroidal neighbor. The gasket is made of a material (e.g., a metal) softer than structural material from which the VV sections are formed, with a melting temperature higher than the operating temperature of the device. The gasket ensures the neighboring VV sections do not make direct mechanical contact with each other. Stated differently, the VV sections comprise a structural material selected to be harder than the material from which gasket is comprised. The gasket material may be ductile and have a yield strength lower than the structural material of the VV sections at operating conditions. The strength of the gasket may also be higher than the stress at operating conditions.

[0055] In embodiments, an isolation layer may be deposited or otherwise provided on mating surfaces of VV sections which are in contact with the gasket. The isolation layer provides both electrical isolation of the sections, corrosion resistance to the blanket fluid, and intermetallic formation. In embodiments, the isolation layer may comprise or be provided as a metal oxide layer, for example.

[0056] The VV sections, support structures, and flanges may be fully assembled and tested at room temperature. The VV sections are inserted into the fusion blanket volume at room temperature with no intrusion into the cryostat of the superconductor magnetic coils used for plasma confinement. Thus, the insertion and assembly can be done with the high DC magnetic fields present, with no change in the operating conditions of the TF and poloidal field coils.

[0057] As the VV and blanket tank are heated up to operating temperatures used during fusion production (typically > 400 °C), the VV sections (or at least some components of the VV sections) expand forcing the VV sections into each other in the toroidal, poloidal, and radial directions. Due to this thermal expansion, neighboring VV sections compress the gasket between them to form a toroidally continuous vacuum sealed chamber for fusion plasma operations. The gasket may also undergo thermal expansion; however, the majority of the contribution to the generation of the seal may be attributed to the VV sections. Since the gasket material is softer than the structural metals of the VV, the resulting stress is concentrated in the gasket and leads to deformation, creating the seal. Once the VV is at operating temperature, i.e., above the melting point of the blanket's working fluid, the blanket volume can then be filled with the working fluid. The VV can be pumped down to vacuum conditions used for the plasma, and fusion plasma operations can commence. Ingress to the plasma volume for vacuum pumping, coolants and auxiliary power transmission are brought in through radial port flanges. Each toroidal section is fully self-contained with the ingress volumes appropriately configured to avoid free neutrons streaming out of the blanket volume.

[0058] The gasket, VV, and internal support structures can be single-use components that eventually reach a lifetime limit due to damage caused by the energetic fusion neutrons. Their replacement is achieved by reversing the installation processes. The blanket working fluid is removed from the volume at the operating temperature. The VV and blanket tank are cooled to near room temperature.

[0059] Once at lower temperatures, the VV sections disassemble from each other due to thermal contraction. Since there is no adhesion, this contraction induces separation at the surfaces between the VV sections and the gasket, breaking the mechanical connection in a controlled manner. The blanket volume can then be filled with water to provide radiological shielding, and the now-detached separate VV sections with structural supports are removed by radial mechanical movement of the flange from their respective port.

[0060] The removed assembly can be translated to a local water pool for cooldown and short-term storage. Once the used VV sections are removed from mechanical connections, a new VV section, its structural supports, and flange can then be installed at room temperature, after w hich the sequence starts again.

[0061] Various embodiments provide replacement and sealing methods that are applicable to maintenance procedures in fusion power systems that use toroidal geometry'. Utilizing the principle outlined in such embodiment removes in-situ physical interaction with the VV structure (e.g., to create or break a vacuum seal). Thus, replacement can be achieved without significant disruption of plant operation, enabling higher plant utilization ratios.

[0062] The amount of time used to replace the VVs is set by the cooling and heating times of relatively small mass objects (e.g., the VV and blanket tank) rather than the approximately hundred-fold more massive magnets. Replacement can therefore be reasonably accomplished on timescales of around a day. Additionally, usage of electronics in high radiation environments can be eliminated, since the mechanical insertion can be controlled from well-shielded radially distant locations, which are further protected by the water pool. Furthermore, the final assembly can be accomplished through temperature control of the VV (e.g., through thermal expansion).

[0063] Figure 1A is a schematic of a fusion power plant 100 in accordance with an embodiment. The fusion power plant 100 includes a fusion reactor 110 having a bioshield 111 within which is housed a plurality of magnetic coils 112, 113 (e.g., toroidal field coils and poloidal field coils) and a plurality of vacuum vessel segments 120. The VV sectionsl20 are coupled to form a vacuum vessel in a central portion of the fusion power plant 100. The VV is the container for the plasma which itself is contained by means of magnetic fields. The vacuum vessel provides a sealed plasma container and provides shielding from the neutrons produced by fusion reactions. In this example embodiment, fusion power plant 100 comprises a tokamak reactor and thus the vacuum vessel is provided having a toroidal shape. As noted above, however, it should be appreciated that the concepts, systems and techniques described herein may be used in connection with any type of fusion reactors including but not limited to stellerators or any type of magnetic confinement fusion device.

[0064] Within the fusion reactor 110, the VV sections 120 separate the blanket volume 118 and the vacuum space 116. The magnetic coils 112, 113 generate magnetic fields to contain the plasma created in the vacuum space 116.

[0065] Each VV sections 120 are connected to an associated extension device 130 comprising a beam 132 (here illustrated as a trussed beam although any type of beam capable of functioning in the manner described below may be used). The extension device 130 may translate the connected VV sections 120 in a radial direction towards or away from a central longitudinal axis 115 of fusion power plant 100. To accomplish this, extension device 130 may move beam 132 in at least a radial direction such as on a track or trolley system. Alternatively, beam 132 may be designed to extend and retract (e.g., in a telescoping fashion) in a radial direction to move VV section 120. This radial translation may be used to move the VV section 120 between the toroidal field (TF) coils 112 and out of the fusion reactor 110 through an opening or port in the bioshield 111. When extension device 130 is extended such that VV section 120 is installed in the reactor (e.g., as shown in Figure 1A), a flange 134 covers the port to provide the bioshield 111 as a closed structure.

[0066] When placed in the fusion reactor 110 the VV sections 120 form a vacuum vessel. In some embodiments, the number of VV sections may be selected based on the desired shape and / or size of the fusion reactor. For example, one fusion reactor may have more (or fewer) VV sections than another fusion reactor.

[0067] Figure IB illustrates an example embodiment in which a vacuum vessel 160 comprises sixteen (16) VV sections 162a-162p forming a single vacuum vessel 160. It should, of course, be appreciated that in other embodiments, a vacuum vessel may comprise fewer or more than 16 sections. After reading the disclosure provided herein, one of ordinary skill in the art will appreciate how to select a number of VV sections to use to form a single vacuum vessel and suit the needs of a particular application.

[0068] In this horizontal slice, the VV sections 162a-162p are located in close proximity to each other. Each VV section 162a-162p has two neighboring VV sections 162a-162p, for example, VV section 162b is neighbored on one side by 162a and on the other side by 162c. Between neighboring VV sections 162a-162p is a gasket 163a-p, for example, gasket 163b is disposed between VV sections 162a and 162b.

[0069] Magnetic coils 161a-161p (which may be the same as or similar to the toroidal field coils 1 12 describe in Fig. 1 A) are loops (e.g. D-shaped loops) with radially inward sections and radially outward sections. As will become apparent from the description below in conjunction with at least Figure 2, the VV sections 162a-162p are disposed between magnetic coils 16 la-161 p and aligned with the open section of the field coil loop.

[0070] In various embodiments, movement of the VV sections can be performed using an extension device. The VV sections are inserted into the fusion reactor and placed in proximity to each other in order to help form the vacuum vessel. By moving the VV sections into place using the extension devices, various tasks involving the attachment and / or detachment can be done safely outside the fusion reactor and the magnetic coils. Additionally, the coils may be left in place (rather than being removed in order to access the VV) and may even be kept operating so as to avoid taking the time to depower the magnets (e.g., magnets in coils 161 a-161p).

[0071] Figure 2 is an illustration of a VV section 220 of a fusion power plant 100 in accordance with an embodiment. Taking VV section 220 as illustrative of all VV sections, as shown in Figure 2, VV section 220 has been fully inserted into a fusion reactor 210 by an extension device 230 coupled thereto. VV section 220 is radially positioned such that it is within open space 221 defined by a plurality' of magnetic coils 212. In this example embodiment, magnetic coils 212 correspond to D-shaped toroidal field (TF) coils 212.

[0072] When position inside the fusion reactor 210, the VV section 220 is held in the blanket volume 218. During operation, this blanket volume 218 may be filled with materials that may be damaging to certain components, accordingly, the materials of the VV should be selected to resist corrosion and other effects.

[0073] Figure 3 is an illustration of the VV section 220 fully extracted from the fusion reactor 210 in accordance with an embodiment. The extension device 230 is used to retract the VV section 220 between the magnetic coils 212 and through a port 219. A port plug 236, seals port 219 when VV section 220 is fully inserted into the fusion reactor 210, as shown in Figure. 2. A beam 238 couples VV section 220 to port plug 236. Port plug 236 also includes a flange 234 to help seal the port 219 when VV section 220 is fully inserted into the fusion reactor 210, as shown in Figure. 2. In some embodiments, the port plug 236 may include connections for use with the VV section 220, for example, to provide coolant, etc.

[0074] Figure 4 is an illustration of a VV section 420 coupled to a port plug 436 via one or more beams 438. VV section 420, port plug 436 and the one or more beams 438 and may be the same as or similar to VV section 220 and one or more beams 238 described above in conjunction with Figures 2 - 3.. As shown, the VV section 420 has a gasket 440 disposed on a mating surface thereof. The VV sections are provided from a structural material (e.g., one or more metal alloys) compatible with a fusion environment. The gasket is comprised of a metal softer than the structural material of the VV sections, with a melting temperature higher than the operating temperature of the fusion device and compatible with a fusion environment.

[0075] As described above in conjunction with Figure IB. when a plurality of VV sections are inserted into a reactor so as to form a closed, sealed vacuum vessel, the VV section mating surface is adjacent a neighboring VV section. Adjacent VV sections are separated by the gaskets situated at a mating surfaces of VV sections. Thus, in this way, VV sections do not make direct mechanical contact with each other, but only with the gasket. As will be described below in conjunction with Fig. 5B, in embodiments, an insulating material is deposited or otherwise provided on surfaces of structural material which are in contact with the gasket to provide both electrical isolation of the sections, corrosion resistance to the blanket fluid, and intermetallic formation. In embodiments, the insulating material may comprise or be provided as a layer of metal oxide disposed between the structural material of the VV sections and the gasket.

[0076] The VV section 420 is connected to the one or more beams 438 at attachment points 422. First ends of the one or more beams 438 are coupled to VV section 420 and second ends of the one or more beams 438 are coupled to a first side (or interior side) of port plug 436. A second side (or exterior side) of port plug 436, which includes flange 434, is coupled to a second beam 432 (which may comprise one or more beams). The second beam may be provided as part of an associated extension device such as extension device 130 described above in conjunction with Figure IBoth the port plug 436 and the VV section 420 may be removed by being detached from the associated beams 432, 438. In such a way, either (or both) may be removed for replacement with a new port plug or VV section.

[0077] VV section 420 also includes one or more alignment structures 429 which are used to align properly align adjacent VV sections during an installation process. Example alignment structures 429 will be described in detail below in conjunction with Figures 9A, 9B.

[0078] Figure 5A is an illustration of a VV section 520 with a gasket 540 on the mating edge of the VV section 520 in accordance with an embodiment. VV section 520 and gasket 540 may be the same as or similar to VV section 420 and gasket 440 described above in conjunction with Figure 4. The combined VV section 500 includes multiple attachment points 522a, 522b. As shown, the attachment points 522a, 522b may be hinge loops; however, in other embodiments, another suitable attachment mechanism may be used. The attachment points 522a. 522b may be the same type of attachment mechanism and / or may use different attachment mechanisms, for example to ensure proper alignment of the VV section 520 when attached to the .

[0079] Figure 5B illustrates an example spacing between two VV sections 520a, 520b in accordance with an embodiment. The two VV sections 520a, 520b are disposed in close proximity, for example, when inserted in a fusion reactor at room temperature. In embodiments the two VV sections 520a, 520b are spaced apart by a distance in the range of about 1 mm to about 10 mm. In embodiments, VV sections 520a, 520b are spaced apart by a distance of about five (5) mm. In some embodiments, the two VV sections 520a, 520b may be closer or farther away. The particular distance by which VV sections 520a, 520b are spaced apart will depend on the particular application (e.g. the particular design of a magnetic confinement fusion device such as a tokamak fusion reactor or a stellerator or any other type of magnetic confinement fusion device).

[0080] Between the two VV sections 520a, 520b is a gasket 540. While shown unconnected, the gasket 540 may be disposed on either of the two VV sections 520a, 520b. The gasket 540 may be of any material suitable for the fusion reactor and the gasket’s proximity to the fusion reaction itself, for example, nickel (Ni). The gasket material may be selected to be softer than the two VV sections 520a, 520b, e.g., more able to deforming or yielding to given pressure, while having a melting point above the operating temperature of the fusion reactor. The gasket 540 may also be chemically compatible with any chemicals introduced to the blanket space of the fusion reactor, for example, molten salts, such as mixture of lithium fluoride (LiF) and bery llium fluoride (BeF2).

[0081] As discussed below, the two VV sections 520a, 520b move together due to thermal expansion, for example, when heated to operating temperatures, so that the two VV sections 520a, 520b compress against the gasket 540. The gasket 540 prevents direct contact between the two VV sections 520a, 520b. The stresses created by the compression are concentrated in the gasket 540 which deforms and creates a vacuum seal.

[0082] The mating surfaces of the two VV sections 520a, 520b may include an insulating layer 524 which can prevent diffusion bonding and electrically insulate the adjacent modules. In some embodiments, insulating layer 524 may be provided as comprise AI2O3.

[0083] Figure 5C is an illustration of the two adjacent VV sections 520a, 520b connected via a gasket 540. VV section 520b is shown in a cut-away view. Figure 5D is a cut-away illustration of the VV section 520b and Figure 5E is a close-up view of the cut-away the VV section 520b. As shown, the VV section 520b includes internal channels 526 which may be used to circulate coolant within the VV section 520b.

[0084] Figure 5F is an illustration of a VV section 520’ in accordance with another embodiment. The VV section 520’ includes attachment points 522’a-522’c and has a gasket 540 on one mating edge. The VV section 520’ also includes a connection 524’a with ports 528’a, 528’b. These ports 528’a, 528’b provide access to internal channels within the VV section 520’. In some embodiments, the internal channels may be used to provide a coolant in order to cool the interior wall 525’ of the VV section 520’. The interior wall 525’ may be formed of a suitable material for the vacuum space, for example, tungsten, while the VV section 520’ may be a different material, such as vanadium. The internal channels may be three (3) mm from the outer surface of the interior wall 525’.

[0085] In some embodiments, the ports 528’a. 528'b may also provide an access point to the interior space of the VV section 520’. In such embodiments, the ports 528’a, 528’b may be used to evacuate the interior of the VV section 520’ in order to create a suitable vacuum.

[0086] The VV section 520’ also features alignment mechanisms 529’a-529’f. These alignment mechanisms 529’a-529’f may function with similar alignment mechanisms of neighboring VV sections in order to prevent the VV section 520’ from sliding or moving out of alignment, for example when undergoing heating.

[0087] Figure 6 A is an illustration of the seal between two adjacent VV sections 620a, 620b in accordance with an embodiment and Figure 6B is a close-up view of the shown in Figure 6 A. Between the two adjacent VV sections 620a, 620b is a gasket 640. As shown, the gasket is disposed within a mating structure of the VV sections 620a. The reciprocal mating structure of VV sections 620b is configured to contact the gasket 640 without contacting the mating structure of VV sections 620a. These structures are present for illustration, other shapes and structures may be used, for example, where the gasket 640 is disposed on the VV section 620b, etc.

[0088] In the embodiment shown, the mating structures of the VV sections 620a, 620b is a tongue and groove style interface where the gasket is disposed in the groove and prevents direct contact between the two VV sections 620a, 620b. In other embodiments, different mating surfaces may be used, for example, concave and convex surfaces with the gasket disposed between the surfaces, etc.

[0089] Figure 7A is a plan view of multiple VV sections 720a-720p forming a single vacuum vessel of a fusion reactor 710. VV sections 720a-720p are coupled to respective ones of beams 732a - 732p which are part of extension devices (such as extension device 130 describe above in conjunction with Fig. 1) which translate the respective VV sections 720a - 720p in a radial direction towards or away from a central longitudinal axis 713 of fusion reactor 710. Thus, beams 732a-732p are configured to move in at least a radial direction such as on a track or trolley system. Alternatively, beams 732a - 732p may be configured to extend and retract (e.g., in a telescoping fashion) in a radial direction to move VV sections 720a - 720p. Such radial translation is used to move the VV sections 720a - 720p between respective toroidal field (TF) coils 712a - 712p and out of the fusion reactor through an opening or port in the bioshield (as described herein).

[0090] Figure 7B is an enlarged view of a portion of the vacuum vessel of Figure 7A. The VV sections 720a-720c are located between respective pairs of the magnetic coils 712 (e.g., TF coils). For example, VV section 720a is positioned between TF coils 712a and 712b; VV section 720b is positioned between TF coils 712b and 712c and so on and so forth. Between the VV sections 720a-720p are gaskets 740a-740p with only gaskets 740a, 740b, 740c and 740p visible in Figure 7B. It should be noted that TF coils 712a - 712p have been extended radially (compared with prior art designed) to enable VV sections 720a -720p to fit between two pairs of coils. For example, when radially translated, VV section 720a fits between TF coils 712a and 712b; when radially translated, VV section 720b fits between TF coils 712b and 712c and so on and so forth.

[0091] Figure 7C illustrates two VV sections 720a-720b at room temperature and Figure 7D shows the two VV sections 720a-720b at operating temperature. When at room temperature, the VV sections 720a-720b are spaced apart from each other by a distance denoted with reference numeral 705 in Figure 7C. In this example embodiment, a gasket 740b is disposed on a portion of VV section 720b.

[0092] As illustrated in Fig. 7D, after being brought to an operating temperature of the fusion reactor 710, thermal expansion causes the VV sections 720a-720b to move closer together so that the VV section 720a contacts the gasket 740b. Stress from the expansion compresses the gasket 740b and creates a vacuum seal. Significantly, surfaces of the structural portions of the VV sections themselves do not come into physical contact (i.e., as noted above, gaskets 740a - 740p between the structural portions of the VV sections form portions of a vacuum seal). Thus, at least portions of each gasket 740a - 740p between the VV sections are exposed to the liquid immersion blanket.

[0093] Figure 8 is an illustration of two VV sections 920a, 920b in accordance with an embodiment and Figure 9 is an enlarged view of portions of the VV sections 920a, 920b. Similar to Figure 6A-6B, the adjacent VV sections 920a, 920b compress a gasket 940. Gasket 940 may be the same as or similar to any of the gaskets described above at least in conjunction with Figures 1A and 4-7D.

[0094] VV sections 920 also comprise one or more alignment structures 929a, 929b which may be the same as or similar to alignment structures 429 described above in conjunction with Figures 4, 5A and 5F. In this example embodiment alignment structures 929a, 929b comprise substantially matching (i.e., aligned) openings 930a, 930b. Although not explicitly shown in Figures 8-9, a pin (e.g. a dowel pin), threaded fastener (e.g. a shoulder bolt) or the like may be disposed through the aligned openings to secure the adjacent VV sections in properly aligned positions during an assembly process. Alignment structures 929a, 929b also help ensure the VV sections 920a, 920b do not move out of alignment during heating or operation. It should, of course, be appreciated that any type of alignment feature or alignment technique may be used including, but not limited to interlocking or mating features which do not require multiple, separate parts (e.g. pins or bolts and openings into which the pins or bolts are inserted or threaded).

[0095] As described above, various embodiments provide techniques for installation and / or replacement of vacuum vessel segments in a fusion power plant.

[0096] Figure 10 is a logic flow diagram that illustrates a method, and a result of execution of computer program instructions, in accordance with various embodiments. In accordance with an embodiment a method performs, at Block 1010, a step of disposing a gasket on a mating surface of a vacuum vessel segment. The vacuum vessel segment is attached to an installation arm at Block 1020. The method also performs, at Block 1030, radially translating the vacuum vessel segment between a pair of toroidal field coils of a fusion power device by moving the installation arm. The vacuum vessel segment is heated, at Block 1040, to cause the vacuum vessel segment to expand and compress the gasket forming a toroidally continuous vacuum seal with a neighboring vacuum vessel segment.

[0097] The sealed vacuum vessel segments may be used to perform power generation. When replacing, the method may be performed in reverse, e.g., the vacuum vessels can be cooled (which causes contraction breaking the seal), translated, and then disconnected from the installation arm.

[0098] By shortening and simplifying the replacement of the neutron-damaged components, various embodiments have significant impacts on the economics of a fusion power plant. Power plants which use various embodiments spend less time inactive to replace the VV. This leads to higher plant availability. Such power plants can mitigate (or reduce) the use of materials or components that can withstand large neutron fluences, since they can be readily replaced. Thus, such fusion power plants have an increased tolerance to operational damage to various components. Lastly, some embodiments enable the rapid iteration of testing (and improving) of fusion components that make up the VV, including first wall materials, power transmission, and cooling, since the damaged or failed components can be removed, inspected, and replaced.

[0099] Various embodiments of the concepts, systems, devices, structures and techniques sought to be protected are described. It should, however, be appreciated that alternative embodiments can be devised without departing from the scope of the concepts, systems, devices, structures and techniques described herein.

[0100] The following definitions and abbreviations are to be used for the interpretation of the claims and the specification.

[0101] It is noted that various connections and positional relationships (e.g., over, below, adjacent, etc.) are set forth between elements in the following description and in the drawings. These connections and / or positional relationships, unless specified otherwise, can be direct or indirect, and the described concepts, systems, devices, structures and techniques are not intended to be limiting in this respect. Accordingly, a coupling or connection of structures or elements can refer to either a direct or an indirect coupling or connection, and a positional relationship between entities can be a direct or indirect positional relationship.

[0102] For purposes of the description herein, the terms "upper," "lower," "right," "left," "vertical," "horizontal,” "top," "bottom," and derivatives thereof shall relate to the described structures and methods, as oriented in the drawing figures. The terms "overlying," "atop," "on top," "positioned on" or "positioned atop" mean that a first element, such as a first structure, is present on a second element, such as a second structure, where intervening elements such as an interface structure can be present between the first element and the second element.

[0103] The terms "connection," “coupled to” or variants thereof can include an indirect "connection" (or coupling) and a direct "connection" (or coupling). As an example of an indirect positional relationship, references in the present description to disposing, arranging or placing element "A" over element layer "B" include situations in which one or more intermediate elements (e.g., element "C") is between element "A" and element "B" as long as the relevant characteristics and functionalities of elements "A" and "B" are not substantially changed by the intermediate elements.

[0104] Similarly, the term "direct contact" means that a first element, such as a first structure, and a second element, such as a second structure, are connected without any intermediary element or structure.

[0105] As used herein, the terms "comprises," "comprising,'’ "includes," "including," "has," "having," "contains" or "containing." or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, a mixture, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such composition, mixture, process, method, article, or apparatus.

[0106] Additionally, the term "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms "one or more" and "one or more" are understood to include any integer number greater than or equal to one, e.g., one, two, three, four, etc. The terms "a plurality" are understood to include any integer number greater than or equal to two, e.g., two, three, four, five, etc.

[0107] References in the specification to "one embodiment, "an embodiment," "an example embodiment," etc., indicate that the embodiment described can include a particular feature, structure, or characteristic, but every embodiment can include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0108] Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

[0109] The terms “approximately,” “substantially” and “about” may be used to mean within ±20% of a target value in some embodiments, within ±10% of a target value in some embodiments, within ±5% of a target value in some embodiments, and yet within ±2% of a target value in some embodiments. For example, the terms “substantially equal” or “substantially equal to” may be used to refer to values that are within ±20% of one another in some embodiments, within ±10% of one another in some embodiments, within ±5% of one another in some embodiments, and yet within ±2% of one another in some embodiments. The terms “approximately,” “substantially” and “about” may include the target value.

[0110] The term “substantially” may also be used to refer to values that are within ±20% of a comparative measure in some embodiments, within ±10% in some embodiments, within ±5% in some embodiments, and yet within ±2% in some embodiments. For example, a first direction that is “substantially” perpendicular to a second direction may refer to a first direction that is within ±20% of making a 90° angle with the second direction in some embodiments, within ±10% of making a 90° angle with the second direction in some embodiments, within ±5% of making a 90° angle with the second direction in some embodiments, and yet within ±2% of making a 90° angle with the second direction in some embodiments.

[0111] It is to be understood that the disclosed subject matter is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The disclosed subject matter is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods, and systems for carry ing out the several purposes of the disclosed subject matter. Therefore, the claims should be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the disclosed subject matter. Although the disclosed subject matter has been described and illustrated in the foregoing exemplary embodiments, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the details of implementation of the disclosed subject matter may be made without departing from the spirit and scope of the disclosed subject matter.

Claims

CLAIMSWhat is claimed is:

1. A vacuum vessel segment for a fusion power device, the vacuum vessel segment comprising: a first toroidal section body shaped in poloidal directions for a given plasma geometry, the first toroidal section body having a mating surface configured to interface with a second toroidal section body; at least one structural attachment point configured to secure the first toroidal section body for radial movement; and a gasket disposed on the mating surface, the gasket being a poloidally continuous thin gasket, wherein the first toroidal section body and the at least one structural attachment point comprise a structural material compatible with a fusion environment of the fusion power device, and wherein the gasket comprises a metal that is softer than the structural material.

2. The vacuum vessel segment of claim 1, wherein the first toroidal section body comprises a metal that has a melting temperature higher than an operating temperature of the fusion power device.

3. The vacuum vessel segment of claim 1, further comprising the second toroidal section body, wherein the gasket is disposed between the first toroidal section body and the second toroidal section body, the gasket is configured to prevent mechanical contact between the first toroidal section body and the second toroidal section body.

4. The vacuum vessel segment of claim 1, further comprising a thin layer of metal oxide deposited on the mating surface.

5. The vacuum vessel segment of claim 1, wherein the first toroidal section body is configured to expand during fusion production by the fusion power device.

6. The vacuum vessel segment of claim 5, wherein the first toroidal section body is configured to expand in at least one of: a toroidal direction, a poloidal direction and a radial direction.

7. The vacuum vessel segment of claim 5, wherein the first toroidal section body is configured to compress the gasket to form a toroidally continuous vacuum seal with a neighboring toroidal section body during the fusion production by the fusion power device.

8. The vacuum vessel segment of claim 7, wherein the first toroidal section body is configured to contract after fusion production by the fusion power device.

9. The vacuum vessel segment of claim 8, wherein the gasket is configured to separate from the neighboring toroidal section body after the fusion production by the fusion power device and break the toroidally continuous vacuum seal.

10. The vacuum vessel segment of claim 1, further comprising a radial port flange configured to allow access to an interior of the first toroidal section body.

11. A fusion power plant, comprising a. toroidal-shaped vacuum vessel (VV) segments in a liquid immersion blanket: b. flanges of inter-coil ports comprising metal alloys compatible with a fusion environment; c. a poloidally continuous thin gasket separating toroidal-shaped VV sections, wherein the poloidally continuous thin gasket: i. is situated at a mating surface interface of one toroidal section to its toroidal neighbor, ii. is comprised of a thin layer of AI2O3, with a melting temperature higher than an operating temperature of the VV, iii. is configured in such a way that the toroidal-shaped VV sections do not make direct mechanical contact with each other, andiv. provides electrical isolation of the toroidal sections, corrosion resistance to a blanket fluid, and intermetallic formation.

12. The fusion power plant of claim 11, wherein the toroidal -shaped VV sections and the poloidally continuous thin gasket are fully extractable at room temperature.

13. The fusion power plant of claim 11, wherein the toroidal-shaped VV sections and the poloidally continuous thin gaskets are single-use components.

14. The fusion power plant of claim 1 1, wherein the toroidal-shaped VV sections are separated from each other by about 10 mm and form vacuum seals by thermal expansion during operation.

15. A method comprising: attaching a vacuum vessel segment to an installation arm; radially translating the vacuum vessel segment between a pair of toroidal field coils of a fusion power device by moving the installation arm.

16. The method of claim 15, further comprising disposing a gasket on a mating surface of the vacuum vessel segment, wherein the mating surface is configured to interface with a second vacuum vessel segment.

17. The method of claim 16, further comprising heating the vacuum vessel segment to cause the vacuum vessel segment to expand in toroidal, poloidal and radial directions and to compress a gasket to form a toroidally continuous vacuum seal with a neighboring toroidal section body.

18. The method of claim 15, wherein attaching the vacuum vessel segment to an installation arm comprises securing at least one structural attachment point of the installation arm to the vacuum vessel segment.

19. The method of claim 15, wherein the method is performed while the fusion power device is generating high magnetic fields.

20. The method of claim 15. wherein attaching the vacuum vessel segment and inserting the vacuum vessel segment into a fusion blanket volume are done at room temperature.

21. The method of claim 15, wherein the method is performed while the fusion power device is generating high magnetic fields.

22. The method of claim 15, further comprising heating the vacuum vessel segment to an operating temperature of the fusion power device.

23. The method of claim 15, further comprising depositing a thin layer of metal oxide on a mating surface of the vacuum vessel segment.

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