High-temperature hydride moderator enabling compact and higher power density cores in nuclear micro-reactors

Abstract

To provide compact and higher power density cores in nuclear micro-reactors.SOLUTION: A reactor core block 200 is disclosed including a fuel channel 202, a heat pipe 204, a primary moderator matrix 206 configured to encompass the fuel channel 202 and the heat pipe 204, and a secondary moderator channel 208 configured to at least partially surround the fuel channel 202, the heat pipe 204 and the primary moderator matrix 206. The secondary moderator channel 208 comprises metal hydride.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Application No. 62 / 984,591, filed March 3, 2020, the contents of which are incorporated by reference herein in their entirety. [Background technology]

[0002] FIELD OF THE INVENTION This invention relates generally to microreactors and, more particularly, to the arrangement of fuel channels, heat pipes, and moderators within the reactor core.

[0003] Electric energy markets can be categorized into centralized and decentralized markets. Centralized markets are based on large (hundreds of MWe) generators and high-capacity, dense transmission and distribution networks. Decentralized, or off-grid, markets instead rely on compact (<15 MWe) generators, typically connected to small, localized distribution networks or microgrids. Current examples of decentralized markets include remote Arctic communities, remote mines, military bases, and island communities. Energy in off-grid markets is currently primarily provided by diesel generators, which leads to high electricity costs, dependence on fossil fuels, load shedding, complex fuel supply logistics, and aging infrastructure. Stringent requirements for off-grid markets include low cost, reliability, flexibility, resilience, sustainability (clean energy), energy security, and rapid installation and minimal maintenance. Nuclear energy can meet all of these demands.

[0004] Microreactors are nuclear reactors capable of producing less than 10 MWe and that can be deployed for remote applications. These microreactors can be packed into relatively small containers, operated without active human intervention, and operated without refueling / replacement for longer periods than conventional nuclear power plants.

[0005] One such microreactor is the eVinci microreactor system, designed by Westinghouse Electric Company. The eVinci system is a heat-pipe-cooled reactor power generation system that utilizes fuel, neutron moderator channels, and heat pipes housed within a compact monolithic core block. The heat pipes act as passive heat-removal devices, efficiently transferring thermal energy from the monolithic core to a heat exchanger on the secondary side of the microreactor. A heat pipe is a hermetically sealed tube containing a small amount of boiling volatile liquid (such as liquid potassium or sodium) at one end (the evaporator section). The vapor travels to the other end (the condenser section), where it condenses and releases its heat of vaporization. The condensed liquid is returned to the other end of the tube by means of a wick, which uses capillary forces to draw the condensate back toward the evaporator section. Additional discussion regarding heat pipes is found in U.S. Patent Application No. 14 / 773,405, published as U.S. Patent Application Publication No. 2016 / 0027536 and entitled "MOBILE HEAT PIPE COOLED FAST REACTOR SYSTEM," and U.S. Patent No. 3,668,070, entitled "NUCLEAR REACTOR WITH HEAT PIPES FOR HEAT EXTRACTION," all of which are incorporated herein by reference.

[0006] Current cores in microreactors utilize uranium fuel that must be enriched to levels much higher than 5% U-235 by weight. One such fuel is high assay low enriched uranium (HALEU), which is uranium fuel enriched to a maximum of 19.75% U-235 by weight. Industrial-scale quantities of uranium enriched above 5% U-235 by weight are limited due to a lack of production capacity at the required scale. This increases the cost of nuclear fuel and, consequently, the cost of microreactors. This ultimately limits the potential market and availability of microreactors to potential customers.

[0007] One such objective of the present disclosure is to provide a lightweight micro-reactor that is inherently safe, capable of operating for several years without replacement, capable of using reduced amounts of HALEU fuel or fuel enriched as low as 5 wt% U-235, and capable of meeting stringent mass and size limitations to allow transport by plane, truck, and conventional road. Summary of the Invention

[0008] In various embodiments, a reactor core block is disclosed that includes a fuel channel, a heat pipe, a primary moderator matrix configured to surround the fuel channel and the heat pipe, and a secondary moderator channel configured to at least partially surround the fuel channel, the heat pipe, and the primary moderator matrix, wherein the secondary moderator channel contains a metal hydride.

[0009] In various embodiments, a reactor core is disclosed that includes a plurality of core blocks, each core block including a fuel channel, a heat pipe, a primary moderator matrix surrounding the fuel channel and the heat pipe, and a secondary moderator channel configured to at least partially surround the fuel channel, the heat pipe, and the primary moderator matrix, wherein the secondary moderator channel includes a metal hydride.

[0010] In various embodiments, a reactor core is disclosed that includes a first array, a second array, and a third array positioned between the first and second arrays. The first array includes a first plurality of fuel channels and a first plurality of heat pipes. The first array is configured to alternate between fuel channels from the first plurality of fuel channels and heat pipes from the first plurality of heat pipes. The second array includes a second plurality of fuel channels and a second plurality of heat pipes. The second array is configured to alternate between fuel channels from the second plurality of fuel channels and heat pipes from the second plurality of heat pipes. The third array includes a first plurality of moderator channels. Each moderator channel from the first plurality of moderator channels contains a metal hydride. The core further includes a moderator matrix. The first array, the second array, and the third array are embedded in the moderator matrix.

[0011] In various embodiments, a reactor core is disclosed that includes a first reactor section, a second reactor section, and an array of moderator channels positioned between the first and second reactor sections. The first reactor section includes a first row of fuel channels and a first row of heat pipes parallel to the first row of fuel channels. The second reactor section includes a second row of fuel channels and a second row of heat pipes parallel to the second row of fuel channels. The first row of fuel channels is interfaced with the array of moderator channels, defining a first angle therebetween. The second row of fuel channels is interfaced with the array of moderator channels, defining a second angle therebetween. The first row of fuel channels is angled with respect to the second row of fuel channels, and the moderator channels contain a metal hydride.

[0012] In various embodiments, a reactor core is disclosed that includes fuel channels, a first heat pipe positioned in a gap between the fuel channels, a second heat pipe positioned in the center of the fuel channels, and a moderator channel containing a metal hydride. [Brief explanation of the drawings]

[0013] The various features of the embodiments described herein, together with their advantages, may be understood by reference to the following description read in conjunction with the accompanying drawings, in which:

[0014] [Figure 1] 1 illustrates a core block in accordance with at least one aspect of the present disclosure.

[0015] [Figure 2] 1 illustrates a reactor core in accordance with at least one embodiment of the present disclosure.

[0016] [Figure 3] 1 illustrates a reactor core in accordance with at least one embodiment of the present disclosure.

[0017] [Figure 4] 1 illustrates a reactor core in accordance with at least one embodiment of the present disclosure.

[0018] [Figure 5] 1 illustrates a reactor core in accordance with at least one embodiment of the present disclosure.

[0019] [Figure 6] 1 illustrates a reactor core in accordance with at least one embodiment of the present disclosure.

[0020] [Figure 7] 1 illustrates a reactor core in accordance with at least one embodiment of the present disclosure.

[0021] Corresponding reference characters indicate corresponding parts throughout the several views. The specific examples detailed herein are illustrative of various embodiments of the invention in one form, and such specific examples should not be construed as limiting the scope of the invention in any manner. DETAILED DESCRIPTION OF THE INVENTION

[0022] Numerous specific details are set forth to provide a thorough understanding of the overall structure, function, manufacture, and use of the embodiments as described in the specification and illustrated in the accompanying drawings. Well-known operations, components, and elements have not been described in detail so as not to obscure the embodiments described herein. The reader will understand that the embodiments described and illustrated herein are non-limiting examples, and thus will recognize that specific structural and functional details disclosed herein may be representative and exemplary. Variations and modifications thereto may be made without departing from the scope of the claims.

[0023] The terms "comprise" (and any form of "comprise," such as "comprises" and "comprising"), "have" (and any form of "having," such as "has" and "having"), "include" (and any form of "including," such as "includes" and "including"), as well as "contain" (and any form of "containing," such as "contains" and "containing"), are open-ended linking verbs. Consequently, a system that "comprises," "has," "includes," or "contains" one or more elements may possess those one or more elements, but is not limited to possessing only those one or more elements. Similarly, a system, device, or apparatus element that "comprises," "has," "includes," or "contains" one or more features may possess those one or more features, but is not limited to possessing only those one or more features.

[0024] 1 illustrates a core block 200 in accordance with at least one embodiment of the present disclosure. Core block 200 includes a plurality of fuel sources or fuel channels 202 and a plurality of heat pipes 204. Such heat pipes 204 are configured to transfer heat generated by fuel channels 202 from core block 200 to a secondary side of the reactor, which may include a heat exchanger for extracting heat from heat pipes 204.

[0025] 1 , the fuel channels 202 and heat pipes 204 may be arranged in a hexagonal pattern. In other embodiments, the fuel channels 202 and heat pipes 204 may be arranged in other patterns, such as a square pattern, an octagonal pattern, a decagonal pattern, or any other pattern that results in a shape with an even number of sides. In other embodiments, the fuel channels 202 and heat pipes 204 may be arranged in other patterns where the resulting shape does not have an even number of sides, such as, for example, a triangular pattern, a pentagonal pattern, or a heptagonal pattern. Other embodiments are envisioned in which the fuel channels 202 and heat pipes 204 have asymmetric patterns within the core block 200.

[0026] As shown in FIG. 1 , the core block 200 may include 12 fuel channels 202 and seven heat pipes 204. In other words, the core block 200 may include more fuel channels 202 than heat pipes 204. In one embodiment, there are two fuel channels 202 for every heat pipe 204. In another embodiment, there are more than two fuel channels 202 for every heat pipe 204. In another embodiment, there is a 1:1 ratio of fuel channels 202 to heat pipes 204. Other embodiments are envisioned in which there are more heat pipes 204 than fuel channels 202. In one aspect, the number of fuel channels 202 adjacent to a heat pipe 204 is variable. As shown in FIG. 1 , the heat pipes 204 at the center of the core block 200 are adjacent to six fuel channels 202, while the heat pipes 204 along the periphery of the core block 200 are adjacent to only four fuel channels 202. Other embodiments are envisioned in which the number of heat pipes 204 adjacent to the fuel channels 202 is the same throughout the core block 200 .

[0027] Core block 200 further includes a primary moderator matrix 206 configured to surround and securely hold fuel channels 202 and heat pipes 204 within core block 200. In one embodiment, primary moderator matrix 206 includes a solid block material with low neutron absorption characteristics and preferably a small moderating effect. In one such embodiment, the primary moderator matrix can include graphite. In another embodiment, the primary moderator matrix can include silicon carbide. In another embodiment, the primary moderator matrix can include aluminum nitride. In another embodiment, the primary moderator matrix can include stainless steel. In another embodiment, the primary moderator matrix can include any combination of graphite, silicon carbide, aluminum nitride, and stainless steel, by way of example.

[0028] The core block 200 may further include a plurality of secondary moderator channels 208. As shown in FIG. 1 , the plurality of secondary moderator channels may partially surround the fuel channels 202 and heat pipes 204 within the primary moderator matrix 206. In another embodiment, the plurality of secondary moderator channels 208 may completely surround the fuel channels 202 and heat pipes 204. In one embodiment, the core block 200 includes only one continuous secondary moderator channel configured to completely surround the fuel channels 202 and heat pipes 204. As shown in FIG. 1 , the secondary moderator channel 208 may have a pack cross-sectional shape. While the secondary moderator channel 208 is shown having a pack cross-sectional shape, other cross-sectional shapes are envisioned, such as a square cross-sectional shape, a hexagonal cross-sectional shape, or any other cross-sectional shape that allows the secondary moderator channel 208 to either partially or completely surround the primary moderator matrix 206, the fuel channels 202, and the heat pipes 204.

[0029] 1 , the secondary moderator channels 208 are configured to overlap the primary moderator matrix 206 such that the secondary moderator channels 208 surround only a portion of the primary moderator matrix 206, while portions of the primary moderator matrix 206 are not surrounded by the secondary moderator channels 208. In one embodiment, the core block 200 includes only one continuous secondary moderator configured to completely surround the fuel channels 202, heat pipes 204, and primary moderator matrix 206.

[0030] In one aspect, the secondary moderator channel 208 can include a chemical form of hydrogen atoms that does not dissociate at the high operating temperatures in the reactor. In one embodiment, this can be achieved by using a high-temperature metal hydride. In one embodiment, the metal hydride can include a metal hydride block. In one embodiment, the metal hydride can include a metal hydride pellet. In one embodiment, the metal hydride can include a metal hydride rod. In one embodiment, the metal hydride can include a metal hydride plate. In one embodiment, the metal hydride can include any combination of a metal hydride block, a metal hydride pellet, a metal hydride rod, or a metal hydride plate.

[0031] In one embodiment, secondary moderator channel 208 may include yttrium hydride. In one embodiment, secondary moderator channel 208 may include cerium hydride. In one embodiment, secondary moderator channel 208 may include yttrium zirconium hydride. In one embodiment, secondary moderator channel 208 may include any combination of yttrium hydride, cerium hydride, and yttrium zirconium hydride. In one embodiment, secondary moderator channel 208 may include any suitable material in which hydrogen atoms do not dissociate at the high operating temperatures within the reactor.

[0032] The advantage of a high-temperature metal hydride moderator, such as the secondary moderator channel 208, is that the metal lattice allows for the dissolution of hydrogen within the lattice and the storage of high concentrations of hydrogen within its structure. This high concentration of hydrogen ensures neutron moderation. At the same time, high-temperature operation is possible because the storage of hydrogen within the hydride does not significantly dissociate into hydrogen gas, unlike water, organic compounds, or hydrogen gas, which operate at higher temperatures. High-temperature hydride moderators also provide a passive method for shutting down the reactor by dissociating the hydrogen and removing it from the core. At a certain temperature above the operating temperature (greater than 600°C) and which can be defined by selecting the appropriate moderator and its stoichiometry, hydrogen atoms dissociate and are released from the secondary moderator 208. As a result, neutron moderation is lost, and the reactor is passively shut down.

[0033] Additionally, the arrangement and use of the secondary moderator channels 208 in conjunction with the primary moderator matrix 206 allows for a reduction in the amount of fuel required to operate the reactor. The use of a high-temperature moderator, such as yttrium hydride, cerium hydride, zirconium hydride, or a combination thereof, in conjunction with a low-absorption structural material, such as graphite, has not previously been used in any commercial or experimental microreactor. In one embodiment, the arrangement and combination of the primary moderator matrix 206 and the secondary moderator channels 208 allows for a reduction in the amount of HALEU fuel required to operate the reactor. In another embodiment, the arrangement and combination of the primary moderator matrix 206 and the secondary moderator channels 208 allows for the use of fuel with lower enrichments of U-235 than HALEU, such as fuel enriched up to 5% U-235 by weight (low-enriched uranium), which is more readily available than HALEU.

[0034] Additionally, the arrangement of the fuel channels, heat pipes, primary moderator, and secondary moderator channels, discussed in more detail below with reference to Figures 2-7, provides even greater fuel mass reduction and ensures the intrinsic safety of the reactor. The combination of the secondary moderator channels 208 with the primary moderator matrix 206, along with the specific arrangement of the fuel channels, heat pipes, primary moderator matrix, and secondary moderator channels, allows for the use of other types of low-density fuel sources, such as, for example, tri-structural isotropic (TRISO) fuel or fuel types enriched up to 5 wt% U3Si2 fuel. The above combination and arrangement of the primary and secondary moderators ensures a negative reactivity coefficient and maintains appropriate time delays between reactivity feedbacks in different core components, thereby enhancing the safety of the microreactor. Additionally, the above features allow the microreactor to operate for longer periods than previously possible, improving fuel economy by an order of magnitude and improving the reactor's levelized cost of electricity (LCOE) by at least 50%.

[0035] 2, a reactor core 300 in accordance with at least one embodiment of the present disclosure is illustrated. The reactor core 300 contains multiple core blocks 200 that are radially repeated within the reactor core 300. The core blocks 200 are housed within a monolith core housing 302, which may be made of a suitable creep-resistant, high-temperature material, such as, by way of example, stainless steel. The monolith core 302 acts as a fission product barrier and as a heat transfer medium between the fuel channels 202 and the heat pipes 204.

[0036] The heat pipes 204 are configured to extend from the core 300 to the secondary side of the reactor so that heat generated by the fuel channels 202 can be absorbed by a heat exchanger. As discussed above, the heat pipes 204 can include an evaporator section and a condenser section. The evaporator section of the heat pipes 204 can be located within the core 300, and the condenser section can be located on the secondary side of the reactor where heat is configured to be extracted. The heat generated by the fuel channels 202 is absorbed by the evaporator section of the heat pipes 204, which vaporizes the working fluid in the heat pipes 204. The vaporized fluid travels to the condenser section and releases its latent heat to the heat exchanger. The working fluid is then returned to the evaporator section (and the core 300) by capillary action of a wick structure within the heat pipes 204.

[0037] The monolith core 302 of the reactor core 300 may be surrounded by a plurality of control drums 310, which include a neutron absorber section 312 and a neutron reflector section 314. The control drums 310 are configured to rotate between a first position and a second position. In the first position, the neutron absorber section 312 of the control drum 310 may be configured to face the monolith core 302, limiting or stopping reactivity within the reactor core 300. In the second position, the neutron reflector section 314 of the control drum 310 may be configured to face the monolith core 302, thereby increasing the reactivity of the reactor core 300 via the Doppler effect.

[0038] In one aspect, the control drum 310 may be the only moving component within the reactor core 300. In one embodiment, all of the control drums 310 are configured to rotate together such that all of the control drums 310 are in either a first position or a second position. In other embodiments, the control drums 310 may be independently rotatable relative to one another. In other embodiments, the control drum 310 may be rotated to a partially rotated position in which a portion of both the neutron absorber section 312 and the neutron reflector section 314 face the monolith core 302. In another embodiment, the control drum 310 is configured to automatically rotate between the first and second positions depending on various factors, such as the temperature within the reactor core 300. In one aspect, when the temperature within the reactor core 300 meets or exceeds a threshold temperature, the control drum 310 may be configured to automatically rotate to the first position, where the neutron absorber section 312 faces the monolith core 302, limiting or shutting down the reactivity of the reactor core 300. In another aspect, when the temperature within the core 300 drops below a threshold temperature, the control drum 310 can be configured to automatically rotate to a second position, where the neutron reflector section 314 faces the monolith core 302, thereby increasing the reactivity of the core 300 via the Doppler effect. In one aspect, the spaces 316 between the control drums 310 can additionally include a neutron reflector to increase reactivity. In another embodiment, the spaces 316 can include a neutron absorber to limit reactivity. In another embodiment, the spaces 316 can be a mixture of a neutron absorber and a neutron reflector.

[0039] The reactor core 300 and the control drum 310 may be housed within a containment vessel (not shown), which may comprise any suitable material configured to house the reactor core 300 and the control drum 310. In one embodiment, the containment vessel may comprise stainless steel, by way of example. The containment vessel may be surrounded by additional neutron absorbers, boron carbide neutron shielding, a cavity for shield cooling, gamma shielding, and a stainless steel outer wall.

[0040] As discussed above, at a certain temperature above the operating temperature, which can be defined by selecting the appropriate moderator and its stoichiometry, hydrogen atoms dissociate and are released from the secondary moderator channel 208. As a result, neutron moderation is lost and the reactor core 300 is passively shut down. Referring again to FIG. 2 , the reactor core 300 can also include a reactor shutdown module 350. The reactor shutdown module 350 provides a secondary passive shutdown system for shutting down the reactor core 300 in conjunction with the passive shutdown provided by the secondary moderator 208. In one embodiment, a neutron absorbing material can be designed to be inserted into the shutdown module 350 at a certain reactor core 300 temperature compared to a predetermined threshold.

[0041] As discussed above, the arrangement provided within core 300 allows for a reduction in the amount of Haleu fuel required for reactor operation. Additionally, this arrangement allows for the use of other fuel types besides Haleu, such as, for example, fuel enriched up to 5% U-235 by weight (low-enriched uranium), tri-layer isotropic (TRISO) fuel, or U3Si2 fuel enriched to 5% by weight. As an example, Haleu TRISO would require 2,000–4,000 kg of 20% U-235 enriched TRISO fuel at a 40% loading fraction to achieve criticality. Using a metal hydride, such as yttrium hydride, the total fuel mass can be reduced to approximately 600 kg of 19.75% U-235 enriched TRISO fuel at a 40% loading fraction. The arrangement of FIG. 2 ensures a negative reactivity coefficient while maintaining appropriate time delays between reactivity feedbacks in different core components, thereby enhancing the safety of the microreactor. Additionally, the arrangement of FIG. 2 allows core 300 to operate for longer periods of time than previously possible, improving fuel economy by orders of magnitude and improving the levelized cost of electricity (LCOE) of the reactor by at least 50%.

[0042] Referring now to FIGURE 3, another embodiment of core 370 is illustrated in accordance with at least one aspect of the present disclosure. Core 370 is similar to core 300, and like numbers are used to illustrate like components. Unlike core 300, core 370 includes five reactor shutdown modules 350 (as opposed to core 300's nine reactor shutdown modules 350), and core 370 does not include fuel channels 202 or heat pipes 204 inserted therein. As can be seen in FIGURE 3, control drum 310, primary moderator matrix 206, and secondary moderator channels 208 extend completely along the length of core 370.

[0043] Referring now to FIG. 4 , another embodiment of a core 420 is illustrated in accordance with at least one aspect of the present disclosure. Similar to the core 300, the core 420 includes multiple core blocks 400 each having a fuel channel 402, a heat pipe 404, a primary moderator matrix (not shown), and a secondary moderator channel 408. As shown in FIG. 4 , the secondary moderator channel 408 has a circular cross-sectional shape. Additionally, the secondary moderator channel 408 is configured such that the core block 400 is completely surrounded by the secondary moderator channel 408. In other embodiments, the secondary moderator channel 408 is configured such that the core block 400 is only partially surrounded by the secondary moderator channel 408. While the secondary moderator channel 408 is shown having a circular cross-sectional shape, other cross-sectional shapes are envisioned, such as a square cross-sectional shape, a hexagonal cross-sectional shape, or any other cross-sectional shape that allows the core block 400 to be completely surrounded by the secondary moderator channel 408.

[0044] Core block 400, like core 300, is housed within a monolithic core housing 422. Monolithic core housing 422 may again be surrounded by multiple control drums 410, each including a neutron absorber section (not shown) and a neutron reflector section 414, with spaces 416 positioned between the control drums 410. Core 420, unlike core 300, includes a single reactor shutdown module 450, which provides a secondary passive shutdown system for shutting down core 420 in conjunction with the passive shutdown provided by secondary moderator 408. While only one reactor shutdown module 450 is illustrated, other embodiments are envisioned in which core 420 includes multiple reactor shutdown modules 450.

[0045] The arrangement provided in core 420 allows for a reduction in the amount of HALEU fuel required to operate the reactor. Additionally, this arrangement allows for the use of other types of fuel besides HALEU, such as, for example, fuel enriched up to 5% U-235 by weight (low-enriched uranium), tri-layered isotropic (TRISO) fuel, or U3Si2 fuel enriched up to 5% by weight. The arrangement of FIG. 4 ensures a negative reactivity coefficient and maintains appropriate time delays between reactivity feedbacks in different core components, thereby enhancing the safety of the microreactor. Additionally, the arrangement of FIG. 4 allows core 420 to operate for longer periods than previously possible, improving fuel economy by orders of magnitude and improving the reactor's levelized cost of electricity (LCOE) by at least 50%.

[0046] Referring now to FIGURE 5, another embodiment of a core 500 is illustrated in accordance with at least one aspect of the present disclosure. The core 500 contains multiple continuous, circular arrays 530, 540, 550 extending outward from the center of the core 500 to a monolith core housing 522. As shown in FIGURE 5, the core 500 can include a first array 530 including alternating fuel channels 502 and heat pipes 504 along its length. The core 500 can also include a second array 540 including multiple moderator channels 508 surrounding or encircling the first array 530. The moderator channels can be similar to the high-temperature metal hydride moderator, such as the secondary moderator 208, discussed above. Additionally, the core 500 may include a third array 550 similar to the first array 530 and including alternating fuel channels 502 and heat pipes 504 along its length, as does the first array 530, and surrounding or encircling the second array 540. In one embodiment, the second array 540 of moderator channels 508 is configured to be positioned between the first array 530 and the third array 550 so as to completely separate the first array 530 from the third array 550. In another embodiment, a gap may be defined between the moderator channels 508 of the second array 540 such that the first array 530 and the second array 550 are only partially separated by the second array 540. The core 500 may include any number of arrays, the rows of which extend from the center of the core 500 to the monolith core housing 522 of the core 500.

[0047] The above-described core 500 is advantageous from a manufacturing standpoint while simultaneously providing the fuel benefits described above (e.g., a lower amount of Haleu, the ability to use other types of fuel, and increased reactor safety). Additionally, although not shown in FIG. 5 , the core 500 may include a primary moderator therein, or a primary moderator matrix similar to the primary moderator matrix 206, configured to securely hold the fuel channels 502 and heat pipes 504, and to have low neutron absorption and preferably a small moderating effect. As discussed above, the primary moderator may include any of graphite, silicon carbide, aluminum nitride, stainless steel, and combinations thereof.

[0048] The rows 530, 540, 550 may be housed within a monolith core housing 522, similar to the cores 300, 420 described above. The monolith core housing 522 may again be surrounded by a plurality of control drums 510, including neutron absorber sections (not shown) and neutron reflector sections 514, and spaces 516 positioned between the control drums 510. Although not illustrated, the core 500 may include any number of reactor shutdown modules to provide a secondary passive shutdown system for shutting down the core 500, along with the passive shutdown provided from the secondary moderator 508.

[0049] 6, another embodiment of a reactor core 600 is illustrated in accordance with at least one aspect of the present disclosure. The reactor core 600 includes discrete core sections 640, each containing an array of fuel channels 602 and heat pipes 604, separated by moderator channels 608, 609. The moderator channels 608, 609 may be similar to the high-temperature metal hydride moderator, such as the secondary moderator 208, discussed above.

[0050] The rows of fuel channels 602, heat pipes 604, and moderator 608 in one furnace section 640 may be angled relative to the rows of fuel channels 602, heat pipes 604, and moderator 608 in an adjacent furnace section 604. In one example, referring to FIG. 6 , the rows of fuel channels 602, heat pipes 604, and moderator channels 608 in one furnace section 640 are configured to interface 630 with rows of moderator channels 609, defining a first angle Θ1 therebetween. Additionally, the rows of fuel channels 602, heat pipes 604, and moderator channels 608 in another furnace section 640 are configured to interface 632 with rows of moderator channels 609, defining a second angle Θ2 therebetween. In other words, the angles of the rows of fuel channels 602, heat pipes 604, and moderator 608 are configured to transition from a first angle Θ1 to a second angle Θ2 at the row of moderator channels 609. In other words, the rows of fuel channels 602, heat pipes 604, and moderator channels 608 in one furnace section 640 are angled relative to the rows of fuel channels 602, heat pipes 604, and moderator channels 608 in another furnace section 640. In one embodiment, Θ1 and Θ2 may be equal. In one embodiment, Θ1 and Θ2 may be different. In one embodiment, the sum of Θ1 and Θ2 may define 90°. In other embodiments, the sum of Θ1 and Θ2 may be greater than 90° or less than 90°. The above arrangement is advantageous from a manufacturing standpoint while simultaneously providing the fuel benefits described above (e.g., a smaller amount of Haleu or the ability to use other types of fuel, and increased safety). Additionally, although not shown in FIG. 6 , core 600 may include a primary moderator therein, or a primary moderator matrix similar to primary moderator matrix 206, configured to securely hold fuel channels 602 and heat pipes 604, and to have low neutron absorption and preferably a small moderating effect.As discussed above, the primary moderator matrix may include any of graphite, silicon carbide, aluminum nitride, stainless steel, and combinations thereof.

[0051] Similar to cores 300, 420, and 500 described above, core 600 may include a monolithic core housing 622 that encloses fuel channels 602, heat pipes 604, secondary moderator 608, and other components of core 600. Monolithic core housing 622 may again be surrounded by multiple control drums 610, each including a neutron absorber section 612 and a neutron reflector section 614, with spaces 616 positioned between control drums 610. Additionally, core 600 may include a reactor shutdown module 650 to provide a secondary passive shutdown system for shutting down core 600 in conjunction with the passive shutdown provided by secondary moderator 608. While only one reactor shutdown module 650 is illustrated, it is envisioned that core 600 may include multiple reactor shutdown modules 650.

[0052] Referring now to FIG. 7 , another embodiment of a reactor core 700 in accordance with at least one aspect of the present disclosure is illustrated. The reactor core 700 contains an array of annular fuel channels 702 and an array of moderator channels 708. The secondary moderator channels may be similar to the high-temperature metal hydride moderator, such as secondary moderator 208, discussed above. In addition, the reactor core contains multiple heat pipes 704, 710. The heat pipes 704 may be positioned in the gaps between the fuel channels 702, while the heat pipes 710 may be positioned in the centers of the fuel channels 702. The mesh-type configuration illustrated in FIG. 7 allows for an increased number of heat pipes 704, 710 per reactor, resulting in an increased amount of power output provided by the reactor core 700. 7, the core 700 may include a primary moderator therein, or a primary moderator matrix similar to the primary moderator matrix 206 discussed above, configured to securely hold the fuel cells 702 and heat pipes 704, 710, while having low neutron absorption and preferably a small moderating effect. As discussed above, the primary moderator may include any of graphite, silicon carbide, aluminum nitride, stainless steel, and combinations thereof.

[0053] Similar to cores 300, 420, 500, and 600 described above, core 700 may include a monolithic core housing 722 that encloses fuel channels 702, heat pipes 704, 710, secondary moderator 708, and other components of core 700. Although not illustrated, monolithic core housing 722 may also be surrounded by multiple control drums containing neutron absorber and neutron reflector sections, with spaces positioned between the control drums. Additionally, core 700 may include any number of reactor shutdown modules to provide a secondary passive shutdown system for shutting down core 700 in conjunction with the passive shutdown provided from secondary moderator 708.

[0054] In addition to the fuel and safety benefits discussed above, the in-core arrangement allows the relatively small core to be packaged in a low-mass container that can be transported in standard and available transport systems (e.g., standard ISO shipping containers) and thereby meets stringent mass and size limitations, allowing transport by plane, truck, and conventional road.

[0055] Various aspects of the subject matter described herein are detailed in the following examples.

[0056] Example 1 - A core block comprising a fuel channel, a heat pipe, a primary moderator matrix configured to surround the fuel channel and the heat pipe, and a secondary moderator channel configured to at least partially surround the fuel channel, the heat pipe, and the primary moderator matrix, wherein the secondary moderator channel contains a metal hydride.

[0057] Example 2 - The core block of Example 1, wherein the primary moderator matrix is ​​selected from the group consisting of graphite, silicon carbide, aluminum nitride, stainless steel, and combinations thereof.

[0058] Example 3 - The core block of Examples 1 or 2, wherein said metal hydride is selected from the group consisting of yttrium hydride, cerium hydride, zirconium hydride, and combinations thereof.

[0059] Example 4 - The core block of any one of Examples 1-3, wherein the secondary moderator channel is selected from the group consisting of a block, a pellet, a rod, or a plate, and combinations thereof.

[0060] Example 5 - The core block of any one of Examples 1-4, wherein the secondary moderator channel is configured to completely surround the fuel channel, the heat pipe, and the primary moderator matrix.

[0061] Example 6 - A reactor core comprising a plurality of core blocks, each core block comprising a fuel channel, a heat pipe, a primary moderator matrix surrounding the fuel channel and the heat pipe, and a secondary moderator channel configured to at least partially surround the fuel channel, the heat pipe, and the primary moderator matrix, wherein the secondary moderator channel contains a metal hydride.

[0062] Example 7 - The core of Example 6, further comprising a control drum comprising a neutron reflector and a neutron absorber.

[0063] Example 8 - The core of Example 7, wherein the control drum is rotatable between a first position and a second position, wherein in the first position, the neutron absorber faces the plurality of core blocks, and in the second position, the neutron reflector faces the plurality of core blocks.

[0064] Example 9 - The core of any one of Examples 6-8, wherein the primary moderator matrix is ​​selected from the group consisting of graphite, silicon carbide, aluminum nitride, stainless steel, and combinations thereof.

[0065] Example 10 - The core of any one of Examples 6-9, wherein the metal hydride is selected from the group consisting of yttrium hydride, cerium hydride, zirconium hydride, and combinations thereof.

[0066] Example 11 - The core of any one of Examples 6-10, wherein the secondary moderator channel is selected from the group consisting of a block, a pellet, a rod, or a plate, and combinations thereof.

[0067] Example 12 - The core of any one of Examples 6-11, wherein the secondary moderator channel is configured to completely surround the fuel channel, the heat pipe, and the primary moderator matrix.

[0068] Example 13 - A reactor core includes a first array, a second array, a third array positioned between the first array and the second array, and a moderator matrix. The first array includes a first plurality of fuel channels and a first plurality of heat pipes. The first array is configured to alternate between fuel channels from the first plurality of fuel channels and heat pipes from the first plurality of heat pipes. The second array includes a second plurality of fuel channels and a second plurality of heat pipes. The second array is configured to alternate between fuel channels from the second plurality of fuel channels and heat pipes from the second plurality of heat pipes. The third array includes a first plurality of moderator channels. Each moderator channel from the first plurality of moderator channels includes a metal hydride. The first array, the second array, and the third array are embedded within the moderator matrix.

[0069] Example 14 - The core of Example 13, further comprising a fourth arrangement comprising a second plurality of moderator channels.

[0070] Example 15 - The core of Example 13 or 14, further comprising a control drum comprising a neutron reflector and a neutron absorber.

[0071] Example 16 - The reactor core of Example 15, wherein the control drum is rotatable between a first position and a second position, and in the first position, the neutron absorber faces the first array, the second array, and the third array, and in the second position, the neutron reflector faces the first array, the second array, and the third array.

[0072] Example 17 - The core of any one of Examples 13-16, wherein the metal hydride is selected from the group consisting of yttrium hydride, cerium hydride, zirconium hydride, and combinations thereof.

[0073] Example 18 - The core of any one of Examples 13-17, wherein the first plurality of moderator channels are selected from the group consisting of blocks, pellets, rods, or plates, and combinations thereof.

[0074] Example 19 - The core of any one of Examples 13-18, wherein the moderator matrix is ​​selected from the group consisting of graphite, silicon carbide, aluminum nitride, stainless steel, and combinations thereof.

[0075] Example 20 - A reactor core comprising a first furnace section, a second furnace section, and a row of moderator channels positioned between the first and second furnace sections. The first furnace section comprises a first row of fuel channels and a first row of heat pipes parallel to the first row of fuel channels. The second furnace section comprises a second row of fuel channels and a second row of heat pipes parallel to the second row of fuel channels. The first row of fuel channels is interfaced with the row of moderator channels defining a first angle therebetween, and the second row of fuel channels is interfaced with the row of moderator channels defining a second angle therebetween, the first row of fuel channels being angled with respect to the second row of fuel channels, and the moderator channels containing metal hydride.

[0076] Example 21 - The core of Example 20, further comprising a control drum comprising a neutron reflector and a neutron absorber.

[0077] Example 22 - The reactor core of Example 21, wherein the control drum is rotatable between a first position and a second position, and in the first position, the neutron absorber faces the first reactor section, and in the second position, the neutron reflector faces the first reactor section.

[0078] Example 23 - The core of any one of Examples 20-22, wherein the metal hydride is selected from the group consisting of yttrium hydride, cerium hydride, zirconium hydride, and combinations thereof.

[0079] Example 24 - The core of any one of Examples 20-23, wherein the moderator channel is selected from the group consisting of blocks, pellets, rods, or plates, and combinations thereof.

[0080] Example 25 - A reactor core comprising a fuel channel, a first heat pipe positioned in a gap between the fuel channels, a second heat pipe positioned in the center of the fuel channel, and a moderator channel containing a metal hydride.

[0081] Example 26 - The core of Example 25, further comprising a control drum comprising a neutron reflector and a neutron absorber.

[0082] Example 27 - The core of Example 26, wherein the control drum is rotatable between a first position and a second position, and in the first position, the neutron absorber faces the fuel channel, and in the second position, the neutron reflector faces the fuel channel.

[0083] Example 28 - The core of any one of Examples 25-27, wherein the metal hydride is selected from the group consisting of yttrium hydride, cerium hydride, zirconium hydride, and combinations thereof.

[0084] Example 29 - The core of any one of Examples 25-28, wherein each moderator channel of the moderator channels is selected from the group consisting of a block, a pellet, a rod, or a plate, and combinations thereof.

[0085] Unless otherwise specifically stated as apparent from the foregoing disclosure, it is recognized that throughout the foregoing disclosure, discussions using terms such as "processing," "calculating," "operating," "determining," or "displaying" refer to the actions and processing of a computer system or similar electronic computing device that manipulates and transforms data represented as physical (electronic) quantities in the computer system's registers and memory into other data similarly represented as physical quantities in the computer system's memory or registers, or other such information storage, transmission, or display device.

[0086] As used herein, one or more components may be referred to as being "configured to," "configurable to," "operable to," "adapted to," "capable of," "compatible to," etc. Those skilled in the art will recognize that "configured to" may generally encompass active components and / or inactive components and / or standby components, unless the context requires otherwise.

[0087] Those skilled in the art will understand that, generally, the terms used herein, and particularly the terms used in the appended claims (e.g., the body of the appended claims), should generally be construed as "open" terms (e.g., including but not limited to "comprising"), the term "having" should be construed as "having at least," the term "comprising" should be construed as "including but not limited to," etc. Furthermore, where a specific number of introduced claim recitations is intended, such intention will be explicitly set forth in the claim; in the absence of such a recitation, for example, to aid in understanding, the appended claims may include the use of the introductory terms "at least one" and "one or more" to introduce claim recitations, but the use of such terms should not be construed as follows: The introduction of a claim recitation with the indefinite article "a" or "an" limits the particular claim that includes that introduced claim recitation to a claim that includes only one, even if the same claim includes an indefinite article such as "one or more" or "at least one or more" introductory phrase and "a" or "an" (e.g., "a" and / or "an" should typically be interpreted to mean "at least one or more" or "one or more"), and is used to introduce the claim recitation.

[0088] Furthermore, even if a specific number of introduced claim recitations is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations" without other modifiers typically means at least two recitations, or more than two recitations). Furthermore, when a convention similar to "at least one of A, B, and C, etc." is used, such a construction is generally intended to be understood by those skilled in the art (e.g., "a system having at least one of A, B, and C" includes, but is not limited to, systems having A alone, B alone, C alone, A and B alone, A and B alone, A and C alone, A and C alone, B and C alone, and / or A, B, and C alone, etc.). When a convention similar to "at least one of A, B, or C, etc." is used, such construction is generally intended to be understood by one of ordinary skill in the art (e.g., "a system having at least one of A, B, or C" includes, but is not limited to, a system having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). Furthermore, one of ordinary skill in the art will understand that typically, in either the description, claims, or drawings, disjunctions and / or phrases presenting two or more alternative terms should be understood to contemplate the possibility of including one of the terms, either of the terms, or both terms, unless the context dictates otherwise. For example, the phrase "A or B" is typically understood to include the possibilities of "A" or "B" or "A and B."

[0089] With respect to the appended claims, those skilled in the art will understand that the operations recited therein may generally be performed in any order. Also, while various operational flow diagrams are presented in a sequence, it should be understood that various operations may be performed in orders other than those depicted, or may be performed simultaneously. Examples of such alternative orderings may include overlapping, interleaving, interrupting, reordering, incremental, preparatory, supplemental, simultaneous, reverse, or other variant orderings, unless the context dictates otherwise. Furthermore, terms such as "responsive to," "related to," or other past adjectives are generally not intended to exclude such variations, unless the context dictates otherwise.

[0090] References to "one embodiment," "one embodiment," "exemplary," "one example," etc. mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment; thus, it should be noted that the appearances of the phrases "in one embodiment," "in one embodiment," "in one example," and "in one example" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0091] Any patent application, patent, non-patent publication, or other disclosure material referred to herein and / or listed in any Application Data Sheet is incorporated herein by reference to the extent the incorporated material does not contradict this specification. Accordingly, to the extent necessary, the disclosure expressly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated herein by reference but that contradicts an existing definition, statement, or other disclosure material set forth herein is incorporated only to the extent that no contradiction arises between the incorporated material and the existing disclosure material.

[0092] The terms "comprise" (and any formations thereof, such as "comprise" and "comprises"), "have" (and any formations thereof, such as "have" and "having"), "include" (and any formations thereof, such as "include" and "includes"), and "include" (and any formations thereof, such as "includes") are open-ended verb linking terms. Consequently, "comprise", "have", "have" or "include" or "comprises" one or more elements includes, but is not limited to, having only those one or more elements. Similarly, "comprise", "have", "have", "includes" or "comprises" an element of a system, device, or "comprising" apparatus includes, but is not limited to, having only those one or more features.

[0093] In summary, many advantages have been described that accrue from employing the concepts described herein. The foregoing description of one or more embodiments has been presented for purposes of illustration and description. It is not intended to be exhaustive or to be limited to the precise form disclosed. Modifications or variations are possible in light of the above teachings. The one or more embodiments were selected and described in order to illustrate the principles and practical applications, thereby enabling those skilled in the art to utilize various embodiments and various modifications suited to the particular use intended. The claims submitted herein are intended to define the overall scope.

Claims

1. A core block comprising: A fuel channel; A heat pipe and a primary moderator matrix configured to surround the fuel channel and the heat pipe; a secondary moderator channel configured to at least partially surround the fuel channel, the heat pipe, and the primary moderator matrix; It is equipped with The core block, wherein the secondary moderator channel contains a metal hydride.

2. 2. The core block of claim 1, wherein said primary moderator matrix is ​​selected from the group consisting of graphite, silicon carbide, aluminum nitride, stainless steel, and combinations thereof.

3. 3. The core block of claim 1 or 2, wherein the metal hydride is selected from the group consisting of yttrium hydride, cerium hydride, zirconium hydride, and combinations thereof.

4. The core block of any one of claims 1 to 3, wherein the secondary moderator channel is selected from the group consisting of a block, a pellet, a rod, or a plate, and combinations thereof.

5. The core block of any one of claims 1 to 4, wherein the secondary moderator channel is configured to completely surround the fuel channel, the heat pipe, and the primary moderator matrix.

6. A reactor core, It has multiple core blocks, each of which: A fuel channel; A heat pipe and a primary moderator matrix surrounding the fuel channel and the heat pipe; a secondary moderator channel configured to at least partially surround the fuel channel, the heat pipe, and the primary moderator matrix; It is equipped with A reactor core wherein the secondary moderator channel contains a metal hydride.

7. 7. The reactor core of claim 6, further comprising a control drum comprising a neutron reflector and a neutron absorber.

8. the control drum is rotatable between a first position and a second position; At the first position, the neutron absorber faces the plurality of core blocks; The reactor core of claim 7 , wherein in said second position, said neutron reflector faces said plurality of core blocks.

9. 9. The reactor core of claim 6, wherein the primary moderator matrix is ​​selected from the group consisting of graphite, silicon carbide, aluminum nitride, stainless steel, and combinations thereof.

10. 10. The reactor core of claim 6, wherein the metal hydride is selected from the group consisting of yttrium hydride, cerium hydride, zirconium hydride, and combinations thereof.

11. The reactor core of any one of claims 6 to 10, wherein the secondary moderator channel is selected from the group consisting of a block, a pellet, a rod, or a plate, and combinations thereof.

12. The reactor core of any one of claims 6 to 11, wherein the secondary moderator channel is configured to completely surround the fuel channel, the heat pipe, and the primary moderator matrix.

13. A reactor core, a first array, the first array comprising: a first plurality of fuel channels; a first plurality of heat pipes; It is equipped with the first array is configured to alternate between fuel channels from the first plurality of fuel channels and heat pipes from the first plurality of heat pipes; The reactor core further comprises: a second array, the second array comprising: a second plurality of fuel channels; a second plurality of heat pipes; It is equipped with the second array is configured to alternate between fuel channels from the second plurality of fuel channels and heat pipes from the second plurality of heat pipes; The reactor core further comprises: a third array positioned between the first array and the second array; the third array comprises a first plurality of moderator channels; each moderator channel from the first plurality of moderator channels contains a metal hydride; The reactor core further comprises: It has a moderator matrix, The core, wherein the first array, the second array, and the third array are embedded within the moderator matrix.

14. 14. The reactor core of claim 13, further comprising a fourth array comprising a second plurality of moderator channels.

15. 15. The reactor core of claim 13 or 14, further comprising a control drum comprising a neutron reflector and a neutron absorber.

16. 16. The reactor core of claim 15, wherein the control drum is rotatable between a first position and a second position, wherein in the first position the neutron absorber faces the first array, the second array, and the third array, and wherein in the second position the neutron reflector faces the first array, the second array, and the third array.

17. 17. The reactor core of any one of claims 13 to 16, wherein the metal hydride is selected from the group consisting of yttrium hydride, cerium hydride, zirconium hydride, and combinations thereof.

18. 18. The reactor core of any one of claims 13 to 17, wherein the first plurality of moderator channels are selected from the group consisting of blocks, pellets, rods, or plates, and combinations thereof.

19. 19. The reactor core of any one of claims 13 to 18, wherein the moderator matrix is ​​selected from the group consisting of graphite, silicon carbide, aluminum nitride, stainless steel, and combinations thereof.

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