Recirculated fluidized pebble bed blanket for tritium breeding and heat recovery in a fusion power plant

Abstract

A breeder blanket is disposed within a stellarator. The breeder blanket defines a breeder zone through which a particle and a flow gas flows. The particle interacts with a neutron generated by a fusion reaction within the stellarator to generate heat. The flow gas absorbs the heat. A separator at an outlet of the breeder blanket separates the flow gas from the particle. The heat in the flow gas is used to generate power.

Description

RECIRCULATED FLUIDIZED PEBBLE BED BLANKET FOR TRITIUM BREEDING AND HEAT RECOVERY IN A FUSION POWER PLANT BACKGROUND

[0001] The subject disclosure relates to devices for magnetic confinement of plasma and, in particular, to an apparatus and method for removing heat from a magnetic confinement device with tritium breeding.

[0002] Fusion devices, such as stellarators, tokamaks, reversed-field pinches, stellarator-tokamak hybrids, and spheromaks, use magnetic fields to confine plasma within a vacuum chamber to achieve controlled nuclear fusion. External magnets are supplied around an exterior region of the vacuum chamber to generate magnetic fields to circulate the plasma within the vacuum chamber. To provide stability to the plasma, the plasma is twisted along a helically twisted toroidal path. This path is reflected in the shape of the vacuum chamber, which similarly form a helically twisted toroid.

[0003] The fusion device generally includes a breeder blanket within the vacuum chamber both for producing tritium and for removing heat and energy from the vacuum chamber. Breeder blankets currently in use need to be replenished occasionally, thereby requiring shut down of the fusion device, which can be costly and time-consuming. Accordingly, it is desirable to employ a breeder blanket in the fusion device that can be operated continuously without interruption.SUMMARY

[0004] An aspect of the present disclosure provides a method of operating a stellarator. The method includes flowing a particle and a flow gas through a breeder zone of a breeder blanket disposed within the stellarator, wherein the particle interacts with a neutron generated by a fusion reaction within the stellarator to generate heat and wherein the flow gas absorbs the heat; and generating power using the heat from the flow gas.

[0005] Another aspect of the present disclosure provides a stellarator including a breeder blanket disposed within the stellarator, the breeder blanket defining a breeder zone through which a particle and a flow gas flows, wherein the particle interacts with a neutron generated by a fusion reaction within the stellarator to generate heat and wherein the flow gas absorbs the heat; and a separator at an outlet of the breeder blanket, the separator configured to separate the flow gas from the particle, wherein the heat in the flow gas is used to generate power.

[0006] Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.INCORPORATION BY REFERENCE

[0007] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. To the extent publications and patents or patent applications incorporated by reference contradict the disclosure contained in the specification, the specification is intended to supersede and / or take precedence over any such contradictory materialBRIEF DESCRIPTION OF THE DRAWINGS

[0008] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings, of which:

[0011] FIG. 1 shows a stellarator in an illustrative embodiment;

[0012] FIG. 2 shows a cross-section of the stellarator that includes a section of the breeder blanket operating through gravity-assisted particle flow, in an illustrative embodiment;

[0013] FIG. 3 shows a particle that is circulated through the breeder zone, in an illustrative embodiment;

[0014] FIG. 4 shows a cross-section of the stellarator that includes a section of the breeder blanket operating through fluidization-assisted particle flow, in an illustrative embodiment; and

[0015] FIG. 5 shows a cross-section of the stellarator that includes a section of the breeder blanket operating through dual-zone gravity-assisted and fluidization-assisted particle flows, in an illustrative embodiment.DETAILED DESCRIPTION

[0016] While various embodiments of the invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed.

[0017] Whenever the term “at least,’’ “greater than,” or “greater than or equal to” precedes the first numerical value in a series of two or more numerical values, the term “at least,” “greater than” or “greater than or equal to” applies to each of the numerical values in that series of numerical values. For example, greater than or equal to 1, 2, or 3 is equivalent to greater than or equal to 1, greater than or equal to 2, or greater than or equal to 3.

[0018] Whenever the term “no more than,” “less than,” or “less than or equal to” precedes the first numerical value in a series of two or more numerical values, thetern “no more than,” “less than,” or “less than or equal to” applies to each of the numerical values in that series of numerical values. For example, less than or equal to 3, 2, or 1 is equivalent to less than or equal to 3, less than or equal to 2, or less than or equal to 1.

[0019] Certain inventive embodiments herein contemplate numerical ranges. When ranges are present, the ranges include the range endpoints. Additionally, every sub range and value within the range is present as if explicitly written out. The term “about” or “approximately” may mean within an acceptable error range for the particular value, which will depend in part on how the value is measured or determined, e.g., the limitations of the measurement system. For example, “about” may mean within 1 or more than 1 standard deviation, per the practice in the art. Alternatively, “about” may mean a range of up to 20%, up to 10%, up to 5%, or up to 1 % of a given value. Where particular values are described in the application and claims, unless otherwise stated the term “about” meaning within an acceptable error range for the particular value may be assumed.Stellarator

[0020] FIG. 1 shows a device 100 for magnetic confinement of plasma for fusion in an illustrative embodiment. For illustrative purposes, the device 100 is disclosed herein as being a stellarator. However, in other embodiments, the device 100 can encompass tokamaks, reversed-field pinches, stellarator-tokamak hybrids, spheromaks, or any other device for magnetic confinement of plasma, particularly for the purpose of fusion. The device 100 can also include non -magnetic fusion energy devices, such as inertial fusion energy devices. The stellarator includes a vacuum chamber 102 that confines a plasma. The vacuum chamber 102 is the form of a helically twisted toroid or a complex toroid that follows the shape of the plasma therein. Electromagnets 104 are disposed around the outer surfaces of the vacuum chamber 102. When activated, the electromagnets 104 create magnetic fields within the vacuum chamber 102 to direct the plasma through the helically twisted toroidal space of the vacuum chamber 102.

[0021] The stellarator is held in place by supports 108. Various ports are connected to the outer surface of the vacuum chamber to control the plasma. The ports can include cooling ports 110 for cooling various components, such as, for example, the electromagnets 104, heating ports 112 for heating the plasma through various methods, such as, for example, electromagnetic radiation induced heating, introducing a neutron beam into the vacuum chamber, or the like; exhaust ports 114 for the removal of particles from the vacuum chamber; and / or diagnostic ports 116 for monitoring the plasma, and so on.

[0022] Also shown in the stellarator is a breeder blanket 120 that is used to transfer heat and hydrogen isotopes out of stellarator. The breeder blanket 120 is morphologically equivalent to a toroid and is disposed in the stellarator such that a fusion zone 122 of the stellarator passes through the center or “doughnut hole” of the breeder blanket 120.Breeder Blanket With Gravity-Assisted Particle Flow

[0023] FIG. 2 shows a cross-section 200 of the stellarator that includes a section of the breeder blanket 120 operating through gravity-assisted particle flow, in an illustrative embodiment. The breeder blanket 120 (minus any inlets and outlets) is a manifold that is morphologically equivalent to a toroid and is deformed to match the contour of the inner wall of a section of the stellarator in which it resides. The manifold resides within the vacuum chamber 102 of the stellarator and defines an internal manifold volume (also referred to herein as a breeder zone 202) that is separate from the vacuum chamber.

[0024] The cross-section 200 shows a first section (first surface 204) of the manifold and a second section (second surface 206). The first surface 204 is proximate to the fusion zone 122, in which a fusion reaction occurs. The second surface 206 is distal from the fusion zone 122. It is understood that while the first surface 204 and the second surface 206 are seen as separate surfaces in the crosssection 200, they are, in reality, sections of a single surface of the manifold in three dimensions.

[0025] Particles circulate through the breeder blanket 120 through the force of gravity or a gravitational force, entering the breeder zone 202 at a top end 208 and exiting the breeder zone 202 at a bottom end 210. A particle feed line 212 provides particles 214 into the breeder blanket 120 through an inlet 216 at the top end 208. A high-pressure gas input line 218 extends through the interior of the particle feed line 212 and into the breeder blanket 120. A low-pressure gas feed line 220 provides low pressure gas which is mixed with the particles 214 in the particle feed line 212 at the top end 208 and into the breeder zone 202 via inlet 216. At the bottom end 210, the particles 214 and the low-pressure gas exit the breeder blanket 120 though an outlet 222.

[0026] The high-pressure gas input line 218 transitions to a gas manifold 224 that bifurcates into two branches which wrap around the first surface 204. The high-pressure gas (which is at a lower temperature than the first surface 204) receives heat to cool the first surface 204 as it travels through the gas manifold 224. At the bottom, the branches of the gas manifold 224 rejoin each other and the gas manifold 224 transitions to a gas outlet line 226. The gas outlet line 226 exits the breeder blanket through the second surface 206. The high-pressure gas can be cooled and recirculated to the high-pressure gas input line 218 to be reintroduced into the gas manifold 224. In an exemplary embodiment, the high-pressure gas is an inert gas. Examples of suitable high-pressure gases are CO2, CO, nitrogen, helium, neon, argon, or a combination thereof.

[0027] A low-pressure gas is mixed with the particles at the inlet 216. In various embodiments, the low-pressure gas can be the same or different from the high pressure gas. Examples of suitable low-pressure gases are CO2, CO, nitrogen, helium, neon, argon, or a combination thereof. In another embodiment, the high-pressure and low-pressure gas streams are a single contiguous stream. In yet another embodiment, a gas stream is not used, and instead the particles move in a vacuum. The low-pressure gas and particles 214 travel (e.g., fall under the weight of gravity) through the breeder zone 202 and are discharged at the outlet 222. A separator 228 at the outlet 222 diverts the particles 214 to travel along a discharge conduit 230. The separator 228 can be a sieve that prevents the particles 214 from passing throughwhile allowing the low-pressure gas to pass through. The particles travel along the discharge conduit 230 to a storage location 232 or inspection location. From the storage location 232, particles 214 are raised to the top end 208 through a recirculation conduit 234 and are fed into the particle feed line 212 and inlet 216. The particles 214 can be raised or elevated through the recirculation conduit 234 using a suitable conveyance device, such as an elevator, by a transport gas circulating upward through the recirculation conduit 234, or by a pneumatic device. The particles can have bimodal or multimodal size distributions. Having such distributions can increase the particle density in comparison to a single size.

[0028] The low-pressure gas that is separated from the particles 214 at the separator 228 travels through a gas discharge conduit 240 to a heat exchanger 242. At the heat exchanger 242, heat in the low-pressure gas can is transferred to a gas or fluid in a secondary loop (not shown). The gas or fluid in the secondary loop is circulated out of the heat exchanger 242 and used to produce power, electricity, and the like. The low-pressure gas exits the heat exchanger 242 through a low-pressure return line 244 which returns the gas to the top end 208 of the breeder blanket 120, where it can be mixed with the particles 214 that are being recirculated back into breeder zone 202.

[0029] In some embodiments, the particles can be passed through the heat exchanger. Whereas the particles can have a majority of the heat capacity and thus can be more effective for exchanging heat that gas, the particle can be also used for heat transfer. Using the particles for heat transfer allows a flow rate of the gas to be significantly reduced. In addition, there is a time constant related to the neutron heating reaching the surface of the particle. The time constant can be selected such that the particles only reach a peak surface temperature once they have reached the heat exchanger.

[0030] A branch line 246 extends from the gas discharge conduit to a tritium Extraction and Removal System (TERS) 248. Low pressure gas can be diverted via the branch line 246 to the TERS 248 for tritium removal. A return line 250 directs the low-pressure gas exiting the TERS 248 to the low-pressure return line 244.

[0031] The geometry of the manifold can be designed to control a flow velocity of the particles through the breeder zone 202. In one embodiment, the manifold can be desired with a constricted region to slow the flow velocity, causing the particles 214 to passes through the breeder zone 202 as through an hourglass.Particle Composition

[0032] FIG. 3 shows a particle 214 that is circulated through the breeder zone, in an illustrative embodiment. The particle 214 includes a lithium-based core 302 surrounded by a porous buffer layer 304 on its outside surface. The layer 304 can comprises a porous buffer and / or a getter layer. The porous buffer layer 304 is surrounded by a structural layer 306 on its outer surface. In one embodiment, the lithium-based core comprises a lithium oxide, such as Li2O. In other embodiments, the lithium oxide is one of lithium silicon oxide, lithium meta-titanate, lithium zirconate, lithium aluminate, or a combination thereof. In yet another embodiment, the lithium-based core can be composed of a lithium orthosilicate. The porous buffer layer 304 comprises a pyrolytic carbon-containing material (e.g., such as carbon nanotubes, carbon black, graphene, graphite, graphitic aerogels, or a combination thereof) while the structural layer 306 comprises a silicon carbide.

[0033] When in the breeder zone 202, the particle 214 is bombarded by neutrons generated by fusion occurring in the fusion zone. The neutrons can collide or scatter from the particles, thereby generating heat which is absorbed by a surrounding gas 310 and earned out of the breeder zone 202. Alternatively, the neutrons can interact with the lithium of the lithium-based core 302, causing a nuclear reaction with lithium to generate tritium and heat. Both the heat and the tritium can be absorbed in the particle or into the surrounding gas 310 and carried out of the breeder zone 202. The surrounding gas is a flow gas that either flows with the particle 214 or controls or assists motion of the particle 214.

[0034] In various embodiments, the particle 214 can have a metal hydride layer. The thickness of the metal hydride layer can control when tritium is released by the particle 214. With the additional metal hydride layer, the particle 214 releasestritium at higher temperatures, thus requiring additional heating of the particle 214 to release the tritium. In certain embodiments, the breeder particles used within the mobile breeder blanket include a multilayer architecture configured to control tritium absorption, retention, and external release. These coated particles may include a ceramic breeder core surrounded by one or more layers of tritium getter, protective coatings, or inert structural materials.

[0035] When placed within the breeder blanket, the getter layer absorbs tritium generated in the breeder core during neutron irradiation. Because the getter layer forms a stable hydride under the operating temperature and pressure of the blanket, tritium remains bound within the particle during circulation. This reduces tritium permeation into structural components and limits the tritium inventory released into the blanket environment. The retention of tritium within the getter layer provides enhanced tritium control and supports inherent safety during off normal events.Examples of the getter layer include a zirconium or titanium hydrides. Examples of the structural materials used in the structural layer 306 include Li2TiOs, a metal oxide, a metal carbide, a metal nitride, a metal boride, a metal silicide, a metal oxycarbide, a metal oxynitride, a metal boronitride, a metal carbonitride, a metal borocarbide, or the like, or a combination thereof. Examples of ceramics that may be used as the structural materials include silicon dioxide, aluminum oxide, titanium dioxide, zirconium dioxide, indium tin oxide, antimony tin oxide, cerium oxide, cadmiumoxide, titanium nitride, silicon nitride, aluminum nitride, titanium carbide, silicon carbide, titanium niobium carbide, stoichiometric silicon boride compounds (SiBn, where n = 14, 15, 40, and so on) (e.g., silicon triboride, SiBs, silicon tetraboride, SiB4, silicon hexaboride, SiB . or the like), or the like, or a combination thereof.

[0036] In an embodiment, the structural layer 306 comprises a thickness of at least 10 to 75 pm.

[0037] The mobility of the breeder blanket enables these coated particles to be transferred out of the plasma facing environment to an external tritium extraction system. Once outside the fusion chamber, the particles may be delivered to an offgassing unit that adjusts temperature, pressure, or other environmental factors toconditions at which the hydride within the getter layer dissociates. Under these conditions, tritium is released from the getter layer and routed to purification units such as thermal cycling absorption systems or permeators. After tritium extraction, particles that retain structural and chemical integrity may be returned to the blanket for continued use.

[0038] The combination of the coated breeder particle architecture with the mobile breeder blanket provides a system in which tritium generation, retention, transport, and release are distributed across controlled environments. The breeder blanket provides the neutron field and circulation capability, while the coated pebble architecture stores tritium within the getter layer during irradiation. The external extraction system provides precise thermal and pressure conditions for tritium release. This integrated approach improves tritium management efficiency, reduces in vessel tritium inventory, and enhances operational safety.Breeder Blanket With Fluidization-Assisted Particle Flow

[0039] FIG. 4 shows a cross-section 300 of the stellarator that includes a section of the breeder blanket 120 operating through fluidization-assisted particle flow, in an illustrative embodiment. Fluidization-assisted particle flow refers to the movement of solid particles facilitated by the presence of a fluid (gas or liquid) that influences their transport, dispersion, or deposition As noted above, the breeder blanket 120 (minus any inlets and outlets) is a manifold that is morphologically equivalent to a toroid and is deformed to match the contour of the inner wall of a section of the stellarator in which it resides. The manifold resides within the vacuum chamber 102 of the stellarator and defines an internal manifold volume (also referred to herein as a breeder zone 202) that is separate from the vacuum chamber 102.

[0040] The cross-section 300 shows a first surface 204 and second surface 206 of the manifold (similar to the surfaces shown in FIG. 2). The manifold has a top end 208 and a bottom end 210. An inlet 302 is located at or near the bottom end 210 of the breeder blanket 120. An outlet 304 is located at the top end 208 of the breeder blanket 120. A particle discharge line 306 is attached to the manifold at the outlet304. A gas feed line 308 passes through the particle discharge line 306 to enter the manifold at the outlet 304.

[0041] The gas feed line 308 transitions to a gas manifold 310 that bifurcates into two branches which wrap around the first surface 204. The high-pressure gas receives heat to cool the first surface 204 as it travels through the gas manifold 310. At the bottom, the branches of the gas manifold 310 rejoin each other and the gas manifold 310 transitions to a gas outlet line 312. The gas outlet line 312 directs the gas to a gas discharge plate 314 that is located at the bottom end of the breeder zone 202. The gas exits the gas manifold 310 as a low-pressure gas and flows upward through the breeder zone 202 to exit the breeder zone 202 at the outlet 304. In various embodiments, the gas is an inert gas such as CO2, CO, nitrogen, helium, neon, argon, or a combination thereof. Particles 214 circulate through the breeder blanket 120 through a process of fluidization (i.e., by fluidizing the particles). The particles are introduced into the breeder zone 202 via the inlet 302 at the bottom end 210 of the breeder blanket 120. The low-pressure gas exiting the gas discharge plate 314 flows vertically upward at a velocity that fluidizes the particles 214 and transports them vertically upward to the top end 208 of the breeder zone 202, out of the breeder blanket 120 via the outlet 304 and into the particle discharge line 306. The particle discharge line 306 channels the particles 214 and the low-pressure gas to a separation system 320, such as a cyclone separation system. The particles 214 drop from the separation system 320 through a discharge conduit 322 to a storage container 324. Meanwhile, the gas is pumped out of the separation system 320 and sent to the heat exchanger and TERS (tritium extraction and removal system).

[0042] At the storage container 324, the particles can be sent for reprocessing and replenishment system 326. From either the storage container 324 or the reprocessing and replenishment system 326, the particles can be returned to the inlet 302 and breeder zone 202 via a particle feed line 328.Breeder Blanket With Hybrid Particle Flow

[0043] In additional embodiments, the breeder blanket may be configured as a hybrid particle transport system that combines features of gravity assisted flow and fluidization assisted flow, or incorporates a multizone architecture that includes fluidized and gravity fed regions within the particulate breeder layer. These hybrid configurations enable optimization of tritium production, thermal management, and tritium extraction efficiency by separating functional regions of the breeder blanket and allowing dynamic control of particle temperature, motion, and residence time.

[0044] With reference now to FIG. 5, in certain embodiments, the breeder blanket 120 includes two functional regions configured according to particle transport and gas handling. The regions are referred to as a cold zone 402 and a hot zone 404. The cold zone 402 is configured for gravity driven particle descent and the hot zone 404 is configured for gas assisted fluidization. The breeder blanket 120 further includes a structural divider between 406 the cold zone and the hot zone, a gas distribution plate 408 positioned to introduce gas into the hot zone, a manifold that conveys particles through the structural divider during a cold-to-hot transition 410, a low pressure gas supply branch 412 that provides gas to the gas distribution plate, a particle tritium extraction and heat exchanger stage 414 located external to the blanket, and a low pressure gas return branch 416 that returns gas to the blanket gas system.

[0045] Breeder particles 214 are introduced into the breeder zone 202 at an upper region of the cold zone through a pebble feed line 328. The particles descend under gravity through the cold zone 402 at a controlled slow velocity. The geometry and thickness of the cold zone are selected to provide extended particle residence time and to stabilize particle temperatures prior to entry into the hot zone 404.

[0046] At a lower region of the blanket, the particles transition from the cold zone to the hot zone by passing through the structural divider 406 via an internal manifold 410. The manifold guides the particles across the divider and positions them for fluidization entry at the base of the hot zone 404. The divider 406 may be configured to provide mechanical support and to isolate thermal or hydraulic conditions between the zones.

[0047] A low-pressure gas line 244 delivers gas to the gas distribution plate 408 located at the base 210 of the hot zone 404. The gas distribution plate 408 releases gas into the hot zone 404 with a velocity sufficient to fluidize the particles and establish upward transport through the hot zone 404 to the top of the breeder blanket 208. The hot zone 404 is positioned adjacent to the first wall 204 and fusion zone 122 and is configured as a thin region to utilize the high neutron flux. The upward fluidized motion provides short residence times, supports heat removal, and promotes transport of tritium bearing gases out of the hot zone 404 with the carrier gas.

[0048] Particles that have been fluidized through the hot zone 404 reach an upper collection region 412 of the blanket after exiting through a particle outlet 304. The exiting particles are directed to a particle tritium extraction and heat exchanger stage 414 located outside the vacuum chamber 102. In this stage, tritium is removed from the particles under controlled conditions and heat is transferred from the particles to a secondary coolant. Particles that satisfy reuse criteria are returned to the blanket at the top of the cold zone 402 to begin a new gravity driven descent.

[0049] The low-pressure gas exiting 240 the hot zone 404 is separated from the particles at the upper collection region 412. A portion of the separated low-pressure gas 416 is routed to the tritium removal and heat exchanger 414 where tritium is extracted from the gas and heat is recovered. The return low-pressure gas stream 418 then merges with the remainder of the low-pressure gas stream. The combined stream is directed to downstream equipment that may include a helium heat exchanger 242 and a TERS 248. After processing, the gas is returned via a low-pressure gas return line 244 to the bottom of the breeder blanket 210 for reuse.

[0050] The two zone configuration establishes a continuous circulation path in which particles enter at the top of the cold zone 402, descend through the cold zone 402, cross the structural divider 406 through a manifold, are fluidized upward through the hot zone 404 by gas from the low pressure gas supply line 244 through the gas distribution plate 408, and are removed at the top of the blanket for tritium extraction and heat recovery 414 before being reintroduced at the cold zone inlet 328. The gashandling branches provide separation, treatment, and return of the low-pressure gas. This arrangement maintains gravity dominated motion in the cold zone, rapid fluidized motion in the hot zone, coordinated solids and gas routing, and continuous in-vessel operation while enabling ex -vessel tritium and heat management.

[0051] In various embodiments, the breeder blanket is configured as a hybrid particle transport system in which gravity driven flow serves as the primary mechanism for particle movement. The use of gravity as the dominant transport driver provides a passive and continuous means of moving breeder particles through the blanket and reduces the number of active components required within the vacuum chamber.

[0052] Stellarator systems exhibit complex three-dimensional geometries that include regions of varying curvature, changing cross sectional area, and local variations in slope. These geometric features can create locations within the breeder blanket where the gravitational driving force is insufficient to maintain continuous downward particle motion. In such locations, particles may accumulate, slow significantly, or fail to progress through the flow path.

[0053] To ensure continuous movement of breeder particles through the blanket, the hybrid system incorporates targeted fluidization zones that operate only in regions identified as susceptible to particle stagnation. Within these zones, a controlled gas flow is introduced to create localized particle aeration or partial fluidization. The gas flow reduces interparticle contact forces, mitigates the formation of stable particle arches, and provides sufficient mobility to overcome geometric constraints. The gas flow rate is selected to achieve the minimum degree of particle mobility required to restore continuous movement without inducing full bed fluidization.

[0054] In certain embodiments, targeted fluidization zones are located at regions of high curvature, concave surface transitions, reduced gravitational slope, or other complex geometric features of the stellarator structure. The placement and design of these zones may be based on predictive modeling, physical testing, orempirical flow evaluation. Each fluidization zone may include gas delivery structures integrated into the blanket, including distributor plates, perforated surfaces, or localized gas injection conduits.

[0055] The hybrid configuration maintains gravity driven flow throughout the majority of the breeder blanket while providing controlled fluidization only where it is desirable to preserve continuous circulation. This approach minimizes gas consumption and reduces mechanical system complexity inside the vacuum chamber. Continuous particle motion supports stable thermal performance, promotes consistent tritium transport, and ensures that breeder particles are periodically transferred to extraction points for tritium removal and thermal conditioning. After processing, the breeder particles may be reintroduced into the blanket at designated inlet locations.

[0056] This configuration provides a breeder blanket design that is compatible with the complex geometry of a stellarator while retaining the reliability and simplicity of gravity dominated particle transport.Integration With External Tritium Extraction and Purification Systems

[0057] In certain embodiments, the mobile breeder blanket is configured to interface directly with an external tritium extraction and purification system such as the Triceratops system. The ability of the breeder blanket to mobilize breeder particles through controlled fluidized flow, gravity driven flow, or a combination of both permits continuous or periodic transfer of particles from the irradiation environment to an ex -vessel processing unit. This mobility distinguishes the blanket from stationary pebble concepts and enables a tritium extraction pathway that does not rely solely on in vessel purge gas systems.

[0058] The breeder blanket provides one or more outlet locations through which tritium enriched breeder particles can be selectively withdrawn. These outlet locations may be positioned at the top of the fluidized hot zone, at the transition region between the hot zone and cold zone, or at another designated point along the particle circulation pathway. In embodiments where the hot zone operates as a fluidized region, the upward transport of breeder particles naturally directs tritium richmaterial toward an upper collection area that can be coupled to a transfer conduit. In embodiments where the blanket uses gravity driven flow as the primary transport mechanism, a lower outlet may be used, with internal routing configured to direct selected breeder particles to the extraction system.

[0059] The mobile breeder blanket is configured so that only a portion of the breeder inventory must be removed at any given time. This enables continuous tritium recovery without interropting blanket operation. Extraction of a small fraction of hot zone particles allows efficient collection of the highest temperature and highest tritium concentration material, which provides favorable conditions for off gassing and minimizes the required throughput of the external processing system.

[0060] The Triceratops system (a circulating solid breeder blanket with spatially separated thermal and extraction regions) includes an off-gassing unit that receives breeder particles from the blanket. This off-gassing unit exposes the particles to controlled thermal and pressure conditions that release tritium retained within the breeder material. Because the breeder particles can be transported out of the reactor vessel through the mobile blanket architecture, all tritium release operations can be performed in a controlled ex vessel environment. This reduces tritium retention inside the blanket and simplifies the thermal and structural requirements of the in- vessel components.

[0061] The interface between the blanket outlet and the Triceratops system may include a transfer conduit, a lock hopper, or a valve system that maintains vacuum integrity while enabling particle passage. The design of this interface allows the breeder blanket to remain sealed from the external environment while providing periodic particle transfer to the off-gassing unit. In certain embodiments, the transfer system uses gravity, pneumatic conveying, or mechanical conveying to move breeder particles into the off-gassing unit.

[0062] After tritium release, the breeder particles may be subjected to analysis or conditioning, and particles that remain structurally intact and retain acceptable lithium content may be reintroduced into the breeder blanket. The blanket inlet maybe positioned at the cold zone entry point, allowing processed particles to begin a new gravity driven descent through the cold zone. This return path forms a closed loop for breeder material circulation that links the in-vessel irradiation environment with the ex-vessel tritium extraction infrastructure.

[0063] The integration of the mobile breeder blanket with the Triceratops system provides a direct tritium extraction pathway that is not constrained by in vessel temperature limits or purge gas behavior. The approach enables high tritium recovery efficiency, improves accountability of tritium inventory, and reduces reliance on complex in vessel processing systems. The ability to couple the blanket to an external extraction system also supports removal and reprocessing of breeder particles at end of life, improving maintainability and enabling partial or full recycling of breeder material.

[0064] In summary, disclosed herein are methods for operating a particlebased breeder blanket in a nuclear fusion system, wherein solid breeder particles are circulated internally through spatially differentiated transport regimes to enable controlled tritium generation, heat management, and particle residence time without removal of the entire breeder inventory.

[0065] In one or more embodiments, a breeder zone of the breeder blanket is partitioned into a hot zone and a cold zone, the hot zone being positioned adjacent to a first wall exposed to a high neutron flux and configured as a relatively thin region, and the cold zone being positioned radially outward from the hot zone and configured as a thicker region. The hot zone is operated under fluidized transport conditions such that breeder particles are conveyed upward with a first, relatively short residence time, while the cold zone is operated primarily under gravity -driven particle flow such that breeder particles descend with a second residence time that is greater than the first residence time. This dual-regime configuration enables efficient neutron utilization near the first wall while stabilizing particle temperature and inventory in the radially outer region.

[0066] In certain embodiments, only a controlled fraction of particles exiting the hot zone is selectively diverted to an external tritium and heat extraction system, while remaining particles are directed into the cold zone. At least a portion of the processed particles may be returned from the external extraction system to an inlet region of the cold zone, thereby establishing a closed or semi-closed particle circulation loop within the breeder blanket. A metered solids transfer assembly may be positioned at an upper collection region of the hot zone to remove a controlled fraction of particles while maintaining vacuum integrity of the fusion system.

[0067] In some embodiments, a divider structure is provided between the hot zone and the cold zone, the divider structure including one or more openings configured to meter interaction between upwardly moving fluidized particles and downwardly moving gravity -driven particles. The geometry, thickness, and slope of the cold zone may be selected to maintain continuous particle descent and provide a residence time sufficient to moderate particle temperature following neutron heating in the hot zone.

[0068] In further embodiments, localized or targeted fluidization may be applied at selected geometric locations within the breeder zone, such as concave regions, high-curvature transitions, or low-slope sections, where gravity-driven flow alone is insufficient to prevent particle stagnation. Outside of such locations, gravity remains the primary transport mechanism. In addition, coolant flow proximate to the hot zone may be periodically restricted or modulated to temporarily increase particle temperature within a controlled range prior to particle transfer or extraction.

[0069] In some embodiments, an extraction controller regulates the fraction of particles diverted from the hot zone based on one or more operating parameters, including measured bed temperature, gas outlet composition, estimated particle residence time, and neutron heating estimates. In this manner, the breeder blanket may be dynamically operated to balance tritium release efficiency, thermal stability, and material inventory.

[0070] Overall, the disclosed methods enable internal circulation of breeder particles wherein particles rise through a fluidized region and descend through a gravity-driven region within the breeder blanket, thereby supporting continuous tritium production and heat extraction while reducing mechanical complexity, minimizing material inventory in high-flux regions, and avoiding full blanket removal during operation.

[0071] The present disclosure relates to fusion reactor systems and, more particularly, to a stellarator comprising a breeder blanket architecture configured to enable controlled particulate circulation, tritium extraction, and thermal management within a magnetically confined plasma environment.

[0072] In one aspect, a stellarator is provided comprising a breeder blanket that defines a hot zone positioned adjacent to a first wall and a cold zone positioned radially outward from the hot zone. The hot zone is configured to occupy a relatively thin region proximate a high neutron flux area, while the cold zone is configured as a thicker region positioned to provide thermal stabilization and extended particle residence time. A gas delivery system is configured to fluidize particles in the hot zone, thereby transporting the particles upward through the hot zone. A gravitational flow path is configured to transport particles downward through the cold zone under gravity-driven motion.

[0073] A selective extraction manifold is coupled to an outlet of the hot zone and is configured to divert a controlled fraction of particles to an external tritium and heat extraction system while directing remaining particles into the cold zone. In certain embodiments, a return conduit introduces processed particles from the external system into an inlet of the cold zone to establish a closed particle circulation loop while maintaining continued breeder blanket operation.

[0074] In some embodiments, a divider structure is disposed between the hot zone and the cold zone. The divider structure includes one or more openings configured to meter communication between upwardly moving fluidized particles and downwardly moving gravity -driven particles. One or more localized fluidization assistregions may be positioned within the cold zone and configured to aerate particles at geometric locations where gravity-driven flow is limited, thereby preventing stagnation while maintaining gravity as the primary transport mechanism across remaining regions.

[0075] The stellarator may further include a metered solids transfer assembly positioned at an upper collection region of the hot zone. The metered solids transfer assembly may include one or more of a lock hopper, a rotary airlock, or a vacuumcompatible valve train configured to remove a controlled fraction of particles while preserving vacuum integrity within the fusion environment.

[0076] In certain embodiments, sensors are provided to measure one or more operational parameters, including bed temperature, gas composition, particle residence time, and neutron heating. A controller may regulate the fraction of particles diverted by the selective extraction manifold based on one or more measured parameters. The gas delivery system may include a gas manifold and a gas discharge plate configured to release gas into the hot zone at a velocity sufficient to fluidize particles.

[0077] In some implementations, the cold zone has a thickness greater than the hot zone and includes a slope selected to maintain continuous downward particle motion under gravity. The selective extraction manifold and return conduit may be arranged to maintain continuous internal particle circulation during particle diversion and return. A targeted fluidization subsystem may be configured to operate only in predetermined regions of the breeder blanket to prevent particle stagnation based on local geometric constraints. In certain embodiments, particles are transported upward through a fluidized region and downward through a gravity -driven region without full bed fluidization across the entire breeder blanket.

[0078] Advantageously, the disclosed stellarator architecture enables continuous particulate circulation within the breeder blanket while reducing material inventory in high-flux regions, improving tritium extraction efficiency, enhancing thermal stability, and minimizing full-bed fluidization requirements.

[0079] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations, or equivalents. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims

CLAIMSWHAT IS CLAIMED IS:

1. A method of operating a stellarator, comprising:flowing a particle and / or a flow gas through a breeder zone of a breeder blanket disposed within the stellarator, wherein the particle interacts with a neutron generated by a fusion reaction within the stellarator to generate heat and wherein the particles and / or the flow gas transports the heat; andgenerating power using the heat from the particles and / or flow gas.

2. The method of claim 1, further comprising flowing the particle vertically downward through the breeder zone via a gravitational force.

3. The method of claim 2, further comprising combining the flow gas and the particle at an inlet at a top end of the breeder blanket.

4. The method of claim 3, further comprising raising the particle from the outlet to the inlet via one of: (i) a conveyance device; and (ii) a transport gas flowing vertically upward.

5. The method of claim 1, further comprising flowing the particle vertically upward through the breeder zone by flowing the flow gas vertically upward through the breeder zone at a velocity that fluidizes the particle.

6. The method of claim 5, further comprising flowing the flow gas around a surface of the breeder zone through a gas manifold and diffusing the flow gas into the breeder zone at a bottom end of the breeder zone.

7. The method of claim 1 , wherein the particle interacts with the neutron to generate heat via at least one of: (i) elastic collision with the neutron; and (ii) creating Tritium through a nuclear reaction with a core of the particle with the neutron.

8. The method of claim 7, wherein the flow gas carries tritium generated using the neutron to a location for extracting tritium from the flow gas.

9. The method of claim 1 , wherein the flow gas is one of: (i) an inert gas; (ii) helium; (iii) neon; (iv) carbon dioxide; and (v) nitrogen.

10. The method of claim 1, further comprising one of: (i) separating the flow gas from the particle at an outlet of the breeder blanket; and (ii) absorbing heat at the particle and / or at the flow gas and generating power using the heat from the flow gas and / or the heat from the particle.

11. A stellarator, comprising:a breeder blanket disposed within the stellarator, the breeder blanket defining a breeder zone through which a particle and a flow gas flows, wherein the particle interacts with a neutron generated by a fusion reaction within the stellarator to generate heat and wherein the flow gas absorbs the heat; anda separator at an outlet of the breeder blanket, the separator configured to separate the flow gas from the particle, wherein the heat in the flow gas is used to generate power.

12. The stellarator of claim 11 , wherein the particle and the flow gas flow vertically downward through the breeder zone via a gravitational force.

13. The stellarator of claim 12, wherein the breeder blanket includes an inlet at a top end and wherein a particle feed line provides the particle to the inlet and a gas input line provides the flow gas to the inlet to combine with the particle at the inlet.

14. The stellarator of claim 13, further comprising one of: (i) a conveyance device; and (ii) a transport gas flowing vertically upward for raising the particle from the outlet at the bottom end to the inlet at the top end.

15. The stellarator of claim 12, wherein the breeder blanket has a constricted region to slow a flow velocity of the flow gas and the particle through the breeder zone.

16. The stellarator of claim 11, further comprising a gas discharge plate at a bottom end of the breeder blanket for releasing the flow gas to flow vertically upward through the breeder zone at a velocity that fluidizes the particle to flow vertically upward through the breeder zone.

17. The stellarator of claim 16, further comprising a gas manifold that flow the flow gas around a surface of the breeder zone then releases the flow gas into the breeder zone via the gas discharge plate.

18. The stellarator of claim 11 , wherein the particle interacts with the neutron to generate heat via at least one of: (i) elastic collision with the neutron; and (ii) creating Tritium through a nuclear reaction with a core of the particle with the neutron.

19. The stellarator of claim 18, further comprising a branch line for directing the flow gas for extracting tritium from the flow gas.

20. The stellarator of claim 11, wherein the flow gas is one of: (i) an inert gas; (ii) helium; (iii) neon; (iv) carbon dioxide; and (v) nitrogen.

21. The stellarator of claim 11, wherein the particle is one of a plurality of particles and the plurality of particles has one of a bimodal particle size distribution and a multimodal particle size distribution.

22. The method of claim 1 , further comprising defining the breeder zone as a hot zone positioned adjacent to a first wall and a cold zone positioned radially outward from the hot zone, wherein the hot zone is configured as a thin region and the cold zone is configured as a thicker region.

23. The method of claim 22, further comprising operating the hot zone with fluidization that transports particles upward with a first residence time andoperating the cold zone with gravity driven flow that transports particles downward with a second residence time that is greater than the first residence time.

24. The method of claim 22, further comprising selectively diverting only a fraction of particles exiting the hot zone to an external tritium and heat extraction system while passing remaining particles into the cold zone.

25. The method of claim 24, further comprising returning at least a portion of processed particles from the external tritium and heat extraction system to an inlet of the cold zone to establish a closed particle circulation loop.

26. The method of claim 22, further comprising providing a divider structure between the hot zone and the cold zone, the divider structure including openings that meter interaction between upwardly moving fluidized particles and downwardly moving gravity driven particles.

27. The method of claim 22, further comprising applying localized fluidization only at geometric locations within the cold zone where gravity driven flow is insufficient to maintain continuous particle motion.

28. The method of claim 22, wherein an extraction controller regulates a fraction of particles diverted from the hot zone as a function of one or more parameters selected from the group consisting of a measured bed temperature, a gas outlet composition, an estimated particle residence time, and a neutron heating estimate.

29. The method of claim 22, further comprising locating a metered solids transfer assembly at an upper collection region of the hot zone, the metered solids transfer assembly configured to remove a controlled fraction of particles from a circulating inventory while maintaining vacuum integrity.

30. The method of claim 22, wherein the hot zone thickness is selected to utilize a high neutron flux region adjacent to the first wall while limiting material inventory in the hot zone.

31. The method of claim 22, wherein the cold zone thickness and slope are selected to provide a residence time that stabilizes particle temperature and maintains continuous descent under gravity.

32. The method of claim 1, further comprising deploying targeted fluidization zones within the breeder zone at concave regions, high curvature transitions, or low slope sections to prevent particle stagnation while maintaining gravity as a primary transport driver along remaining path segments.

33. The method of claim 1, further comprising periodically restricting coolant flow proximate to the hot zone to increase particle temperature within a controlled range prior to particle transfer from the breeder blanket.

34. The method of claim 1, further comprising transporting particles through an internal circulation path wherein particles rise through a fluidized region and descend through a gravity driven region within the breeder blanket without removal of the entire blanket.

35. A stellarator, comprising:a breeder blanket that defines a hot zone adjacent to a first wall and a cold zone positioned radially outward from the hot zone,a gas delivery system configured to fluidize particles in the hot zone to transport the particles upward,a gravitational flow path configured to transport particles downward through the cold zone, anda selective extraction manifold coupled to an outlet of the hot zone and configured to divert a fraction of particles to an external tritium and heat extraction system while directing remaining particles to the cold zone.

36. The stellarator of claim 35, further comprising a return conduit configured to introduce processed particles to an inlet of the cold zone to complete a closed particle circulation loop.

37. The stellarator of claim 35, further comprising a divider structure between the hot zone and the cold zone, the divider structure comprising openings that meter communication between upwardly moving fluidized particles and downwardly moving gravity driven particles.

38. The stellarator of claim 35, further comprising one or more localized fluidization assist regions positioned within the cold zone and configured to aerate particles at locations where gravity driven flow is limited by geometry.

39. The stellarator of claim 35, further comprising a metered solids transfer assembly at an upper collection region of the hot zone, the metered solids transfer assembly comprising one or more of a lock hopper, a rotary airlock, or a vacuum compatible valve train.

40. The stellarator of claim 35, further comprising sensors configured to measure one or more of bed temperature, gas composition, particle residence time, or neutron heating, and a controller configured to regulate a fraction of particles diverted by the selective extraction manifold based on the measured parameters.

41. The stellarator of claim 35, wherein the gas delivery system includes a gas manifold and a gas discharge plate positioned to release gas into the hot zone at a velocity sufficient to fluidize particles.

42. The stellarator of claim 35, wherein the cold zone has a thickness greater than the hot zone and a slope selected to maintain continuous downward particle motion under gravity.

43. The stellarator of claim 35, wherein the selective extraction manifold and the return conduit are arranged to maintain continuous circulation of particles within the breeder blanket during particle diversion and return.

44. The stellarator of claim 11, further comprising a targeted fluidization subsystem configured to operate only in predetermined regions of the breeder blanket to prevent particle stagnation based on local geometric constraints.

45. The stellarator of claim 11, further comprising a circulation path in which particles are transported upward through a fluidized region and downward through a gravity driven region without full bed fluidization across the entire breeder blanket.

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