Devices, systems, and methods for adjusting the output of a reactor core.

Abstract

Disclosed herein is an adjustable core assembly for a nuclear reactor. The adjustable core can include a plurality of reactivity control cells configured to accommodate reactivity control rods and a plurality of unit cells. The plurality of unit cells define a radial dimension corresponding to an initial output power of the core. Each unit cell of the plurality of unit cells is configured to accommodate a fuel configured to generate energy and a heat pipe configured to transfer thermal energy away from the core. Each unit cell of the plurality of unit cells can be radially coupled to an adjacent unit cell to change its radial dimension, the changed radial dimension corresponding to an adjusted output power of the core, the adjusted output power of the core being different from the initial output power of the core.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Non - Provisional Patent Application No. 17 / 084,365, entitled "DEVICES, SYSTEMS, AND METHODS FOR ADJUSTING THE OUTPUT OF A REACTOR CORE," filed on October 29, 2020, the content of which is hereby incorporated by reference in its entirety.

[0002] Government Contract This invention was made with government support under contract DE - NE0008853 awarded by the U.S. Department of Energy. The government has certain rights in this invention.

[0003] This disclosure generally relates to nuclear power generation and, more particularly, to improved devices configured to adjust the output of a reactor core.

Summary of the Invention

[0004] The following summary is provided to facilitate an understanding of some of the innovative features specific to the aspects disclosed herein and is not intended to be a complete description. A complete understanding of the various aspects can be obtained by taking the entire specification, claims, and abstract together.

[0005] In various embodiments, a tunable core for a nuclear reactor is disclosed. The tunable core may include a plurality of reactivity control cells, each of which includes a reactivity control rod interface configured to accommodate reactivity control rods comprising neutron-absorbing material; and a plurality of unit cells, each of which includes a plurality of fuel channels configured to accommodate fuel, and each of which includes a plurality of heat pipe channels configured to accommodate heat pipes configured to transfer thermal energy away from the core, wherein each of the unit cells is arranged radially adjacent to another unit cell of the plurality of unit cells, thereby defining the radial dimension of the tunable core, the radial dimension corresponding to a predetermined output power of the tunable core.

[0006] In various embodiments, adjustable core assemblies for nuclear reactors are disclosed. The adjustable core assembly includes a plurality of reactivity control cells, each of which is configured to house a reactivity control rod comprising a neutron-absorbing material; and a plurality of unit cells, each of which is configured to house a radial dimension corresponding to the initial power output of the core, each of which is configured to house a fuel configured to generate energy, and each of which is configured to house a heat pipe configured to transfer thermal energy away from the core, wherein each of which is configured to be radially coupled to an adjacent unit cell of the plurality of unit cells, thereby changing the radial dimension, the changed radial dimension corresponding to the adjusted power output of the core, and the adjusted power output of the core being different from the initial power output of the core.

[0007] In various embodiments, a method for adjusting the output power of a reactor core, wherein the core comprises a plurality of unit cells, each unit cell of the plurality of unit cells configured to contain fuel configured to generate energy, each unit cell of the plurality of unit cells configured to contain heat pipes configured to transfer thermal energy away from the core, the initial number of unit cells in the plurality of unit cells corresponds to the initial output power of the core, the method comprising: determining an amount of fuel based at least in part on a desired output power of the core corresponding to the intended use of the reactor; determining a number of heat pipes based at least in part on a predetermined requirement of the core based at least in part on the intended use of the reactor; determining a number of unit cells based at least in part on a determined number of heat pipes corresponding to an amount of fuel corresponding to the desired output power and the predetermined requirement; and mechanically changing the plurality of unit cells so that the initial number of unit cells becomes the determined number of unit cells, thereby changing the core so that the initial output power of the core becomes a desired output power of the core.

[0008] These and other objects, features, and characteristics of the present invention will become more apparent by considering the following description and the appended claims (all of which form part of this specification) with reference to the appended drawings, in which similar reference numerals indicate corresponding parts in various figures, along with the methods and functions of the relevant elements and their combination with manufacturing components and economics. However, it should be expressly understood that the drawings are for illustrative and explanatory purposes only and are not intended to define any limitations of the present invention. [Brief explanation of the drawing]

[0009] Various features of the embodiments described herein are described in detail in the appended claims. However, with respect to both the organization and the method of operation, various embodiments, along with their advantages, can be understood in accordance with the following description made in conjunction with the following appended drawings. [Figure 1]An example of a perspective view of a core design that may be modified to adjust reactor output is shown, according to at least one non-limiting aspect of this disclosure. [Figure 2] An example of a top view of the adjustable core design of Figure 1 is shown, according to at least one non-limiting aspect of this disclosure. [Figure 3] An example of a top view of a unit cell of the adjustable core design of Figures 1 and 2 is shown according to at least one non-limiting aspect of this disclosure. [Figure 4A] An example of a perspective view of the unit cell in Figure 3 is shown according to at least one non-limiting aspect of this disclosure. [Figure 4B] An example of a perspective view of the core reflector configuration of Figures 1 and 2 is shown according to at least one non-limiting aspect of this disclosure. [Figure 4C] An example of a top view of the unit cell in Figure 3 is shown according to at least one non-limiting aspect of this disclosure. [Figure 5] An example of a perspective view of the adjustable core shown in Figures 1 to 4 is provided, according to at least one non-limiting aspect of this disclosure. [Figure 6] An example of a cross-sectional perspective view of the core in Figures 1 to 5 is shown according to at least one non-limiting aspect of this disclosure. [Figures 7A-7B] The temperature distribution of at least a portion of the core shown in Figures 1 to 6 is illustrated according to at least one non-limiting aspect of this disclosure. [Figure 8A-8B] An example of a comparison of the stress distribution in at least a portion of the core shown in Figures 1 to 6 with the stress distribution in a conventional monolithic core is provided according to at least one non-limiting aspect of this disclosure. [Figures 9A-9C] The expected temperature and stress distributions for the maximum expected power level of the core shown in Figures 1 to 6 are illustrated in at least one non-limiting aspect of this disclosure. [Figure 10] This disclosure illustrates a method for adjusting the output power of a reactor core, according to at least one non-limiting aspect of this disclosure.

[0010] Corresponding reference letters indicate the corresponding parts throughout several figures. The examples described herein illustrate various aspects of the invention in one form, and such examples should not be construed as limiting the scope of the invention in any way. Detailed description of the invention

[0011] Numerous specific details are provided to provide a complete understanding of the overall structure, function, manufacture, and use of the embodiments described herein and illustrated in the accompanying drawings. Known operations, components, and elements are not described in detail so as not to obscure the embodiments described herein. The reader should understand that the embodiments described and illustrated herein are non-limiting examples, and therefore the specific structural and functional details disclosed herein may be representative and illustrative. Variations and modifications thereto may be made without departing from the claims. Furthermore, it should be understood that terms such as “forward,” “rear,” “left,” “right,” “upward,” and “downward” are for convenience and should not be interpreted as limiting terms. Furthermore, it should be understood that terms such as “forward,” “rear,” “left,” “right,” “upward,” and “downward” are for convenience and should not be interpreted as limiting terms.

[0012] In the following description, similar reference numerals indicate similar or corresponding parts in several drawings. Furthermore, it should be understood that terms such as “forward,” “rear,” “left,” “right,” “upward,” and “downward” are for convenience only and should not be interpreted as limiting terms.

[0013] Before describing in detail the various embodiments of the articulated manipulator, it should be noted that the examples are not limited to their application or use to the details of the configuration and arrangement of the components illustrated in the accompanying drawings and descriptions. The examples may be implemented or incorporated in other embodiments, variations, and modifications, and may be practiced or implemented in various ways. Furthermore, unless otherwise indicated, the terms and expressions used herein have been selected for the convenience of the reader to illustrate the examples and are not intended to limit them. It will also be understood that one or more of the embodiments, expressions of embodiments, and / or examples described below may be combined with any one or more of the other embodiments, expressions of embodiments, and / or examples described below.

[0014] This disclosure pertains to devices, systems, and methods for adjusting the output of a reactor core. Nuclear reactors are typically manufactured to produce a specific output power for their intended use. Apart from the application-specific power requirements, the design and manufacture of a reactor must also comply with various internal and / or government safety regulations. For example, a reactor must be designed and manufactured to comply with several different criteria, e.g., (i) the ability to accommodate several different fuels and / or moderators (e.g., graphite, beryllium oxide, yttrium hydride, zirconium hydride), (ii) the ability to be thermomechanically self-sufficient during normal operation and assumed failures, (iii) the ability to support available manufacturing capabilities, (iv) the ability to integrate with existing core components (e.g., radial reflectors), and (v) the ability to be scalable for use in both transportable and mobile reactors. Conventional reactors were large, which limited their applications. However, both size constraints and limited applications facilitated manufacturers to focus on a small number of conventional designs that could be commercialized in compliance with applicable requirements and / or regulations.

[0015] As reactor sizes continue to shrink, so does their versatility. New reactors, including microreactors, can be effectively implemented in a growing number of emerging and unprecedented applications. However, the reliability of the reactor design and performance, as well as its compliance with applicable requirements and / or regulations, are more critical than ever. For example, as reactors become more versatile, they will become more widespread, and therefore, the impact of reactor failures may be greater and more widespread. A single reactor design is not suitable for expanding applications. For now, creating a new design for each new application is not commercially feasible and may be potentially unsafe. For example, the endless development of new reactor designs can be accompanied by increased costs and risks associated with manufacturing and operation. In other words, the "one size" reactor is not a one-size-fits-all solution. Therefore, there is a need for improved devices, systems, and methods to adjust the output of the core design while maintaining compliance with applicable requirements and / or regulations. Such devices, systems, and methods would allow the reactor to be easily modified for each new application while maintaining the stability of the reactor's manufacture and operation.

[0016] Referring here to Figure 1, a perspective view of a core 100 that can be modified to adjust the output of a reactor according to at least one non-limiting aspect of the present disclosure is illustrated. According to the non-limiting aspect of Figure 1, the core 100 includes a plurality of unit cells 102 that collectively form a hexagonal core boundary. Each unit cell 102 may be configured to house a heat pipe and a quantity of fuel (e.g., in the form of rod and / or stack configurations) and, collectively, can generate nuclear energy and manage thermal energy throughout the core 100. According to some non-limiting aspects, one or more unit cells 102 may further include a moderator configuration that can slow down neutrons emitted from the fuel. As illustrated in the non-limiting aspect of Figure 1, the unit cells 102 may be arranged such that the core 100 includes a hexagonal geometric shape. However, in other non-limiting aspects, the unit cells 102 may be arranged such that the core 100 includes one of several different geometric configurations, depending on the intended application and / or user preference.

[0017] Referring further to FIG. 1, the core 100 may further include a plurality of reactivity control cells 104. Each cell 104 may be configured to accommodate a reactivity control rod configuration, which may operate collectively to control the fissions occurring within the core 100, and thus may prevent the core 100 from reaching critical temperature in the event of a reactor and / or power supply failure or a criticality accident. According to various non-limiting aspects, the amount of fissions may be reduced or completely eliminated within the core 100, the latter of which may shut down the core. The reactivity control rods contemplated by the present disclosure may include neutron absorbing materials and may be configured to be inserted into the reactivity control cells 104 to slow down and / or stop the nuclear reaction in an emergency event. The reactivity control configuration of the core 100 of FIG. 1 is transportable and represents a useful feature of modern microreactors having a wider range of commercial applications. Thus, the emergence of microreactors may increase the penetration rate of nuclear power technology and make safety a higher priority.

[0018] According to a non-limiting aspect of FIG. 1, the core 100 may further include a reflector 106. For example, the reflector 106 may include one or more plates composed of a thick neutron moderating material (e.g., beryllium oxide, graphite, and / or combinations thereof) and configured to substantially surround the core 100. The reflector 106 may further include a plurality of control drums 108 configured to accommodate neutron absorbing materials. In the event of a reactor and / or power supply failure, the control drums 108 may rotate inwardly towards the core 100 such that the absorbing materials may shut down the reactor. According to some non-limiting aspects, the reflector 106 may additionally include a gamma shield configured to provide gamma and neutron shielding. As illustrated in the non-limiting aspect of FIG. 1, the reflector 106 may be arranged in a circular configuration surrounding a plurality of unit cells 102 arranged in a hexagonal pattern. However, in other non-limiting aspects, the reflector 106 may be arranged to form any of several different geometric configurations around the plurality of unit cells 102 depending on the intended application and / or user preference.

[0019] Referring further to Figure 1, the reflector 106 may be segmented to ensure a gap exists between the unit cells 102 and the reflector 106, as a means of controlling and promoting a desired amount of heat transfer. For example, the reflector 106 may be formed from a plurality of modular plates integrated to create the aforementioned gap. However, in other non-limiting embodiments, the reflector 106 may be formed integrally. In addition, the reflector 106 may be further configured to extend along an axial direction D1 defining the length L of the core 100. The plurality of unit cells 102 may also be configured to extend along the length L of the core 100.

[0020] Some microreactors function as "nuclear batteries," generating electricity using energy from the fission of nuclear materials (e.g., uranium in oxide, metallic, and / or silide forms). Since the unit cell is configured to contain fuel containing such radioactive isotopes in any form, the length L of the core 100 can correspond to the desired power output of the reactor and the fuel mass required to maintain criticality. Additionally and / or alternatively, the improved versatility of microreactors means that the core 100 must be configurable for a wide variety of applications, many of which may have size and / or weight constraints. Therefore, the design of the core 100 is strictly configurable so that the length L adapts to the power, size, and / or weight requirements of the reactor.

[0021] Referring now to FIG. 2, there is shown a top view of the reactor design of FIG. 1 according to at least one non-limiting aspect of the present disclosure. FIG. 2 illustrates how a plurality of unit cells 102 and a plurality of reactivity control cells 104 may be specifically arranged to establish the hexagonal configuration of a non-limiting aspect of the core 100. It is also clear that each unit cell 102 of the plurality of unit cells 102 and each reactivity control cell 104 of the plurality of reactivity control cells 104 similarly include a hexagonal configuration. However, it is to be understood that the hexagonal configuration is shown for purposes of illustration only. Accordingly, the present disclosure contemplates other non-limiting aspects in which the unit cells 102 include any number of geometric configurations (e.g., square, circular, triangular, rectangular, pentagonal, octagonal) such that the core 100 may include any number of geometric configurations.

[0022] With further reference to FIG. 2, the plurality of unit cells 102 and the plurality of reactivity control cells 104 may be arranged along a radial direction D2, thereby defining the radial dimension R of the core 100. Specifically, the non-limiting aspect of FIG. 2 illustrates a core 100 having 61 unit cells 102. However, the present disclosure contemplates other non-limiting aspects in which the core 102 includes any number of unit cells 102. In fact, the ability to easily add or subtract a number of unit cells 102 to the core 100 without dramatically changing its design allows the core 100 to be easily scaled according to the intended use and / or user preference. Thus, the output of the design of the core 100 may also be easily adjusted for a plurality of uses and requirements. For example, a user may change the radial and / or axial dimensions of the core 100 by adding or subtracting unit cells 102 to the core 100. Since the unit cells are configured to contain fuel including radioactive isotopes, increasing or decreasing the size of the radial dimension R may change the output of the core 100. Accordingly, the radial dimension R of the core 100 may correspond to the desired output of the reactor according to the intended use and / or user preference. Additionally and / or alternatively, the radial dimension R of the core 100 may be specifically configured to meet a plurality of size and / or weight requirements that may vary depending on the use.

[0023] Where used in this disclosure, the term “radial” refers to any direction extending from the center of the core 100 when viewed from above. Therefore, the use of the term “radial” should not be limited to a circular or circular-like configuration, nor should it be construed as implying that the core 100 in Figures 1 and 2 is limited to a circular or circular-like configuration. For example, this disclosure intends to describe non-limiting embodiments in which the core 100 includes a rectangular configuration. According to such embodiments, the core 100 may include one or more radial dimensions of variable length.

[0024] Referring further to Figure 2, the multiple unit cells 102 and the multiple reactivity control cells 104 can be integrally formed from a solid block of material (e.g., graphite). Thus, each internal feature of the unit cell 102, such as heat pipe channels, fuel channels, moderator channels, and / or similar, can be extracted from the solid block of material and integrally formed therefrom. However, according to other non-limiting embodiments, each unit cell 102 of the multiple unit cells 102 and each reactivity control cell 104 of the multiple reactivity control cells 104 can be modularly formed and integrated within the core block to facilitate the adjustability of the core design. In any case, the core 100 can be readily manufactured to include any number of unit cells 102 and / or reactivity control cells 104. This allows the design of the core 100 to be easily scalable and to provide a clear improvement over known furnaces. For example, changing the number of unit cells 102 and reactivity control cells 104 may allow the user to change the radial dimension R and length L of the core 100 (Figure 1), thereby changing its output and flexibility for applications with inherent output and / or spatial constraints. However, the design of the core 100 remains essentially the same, allowing for predictability of manufacture and performance regardless of differences in output and size. These features also reduce the amount of non-repetitive engineering required to design for new applications, facilitating manufacturing consistency and component standardization. The core 100 in Figures 1 and 2 may be expandable or contractible as a means of adjusting its output, but expansion or contraction should further consider the power rating of the implemented heat pipes, the appropriate number of reactivity control rods required for the adjusted output, and the effectiveness of the control drum.

[0025] Referring further to Figure 2, each of the cells 102 may be configured to be self-sufficient. As used in this disclosure, “self-sufficient” should be interpreted as the ability of each unit cell 102 to independently dissipate the heat generated by the fuel oriented within the unit cell 102 via the heat rods. However, as a safety measure, the unit cells 102 are positioned so that the gap G between any two adjacent unit cells 102 is 2 millimeters or less. In this way, in the event of one or more heat pipes failing within any given unit cell 102, adjacent unit cells 102 can be positioned close enough to the unit cell 102 having the failed heat pipe to transfer excess heat away from the core 100. Thus, the unit cells 102 may be configured to ensure that the core 100 can operate at an acceptable temperature even when a unit cell is no longer self-sufficient due to a heat pipe failure.

[0026] In addition, the unit cells 102 in Figure 2 may be geometrically configured and oriented relative to each other in a triangular pattern, the triangular pattern including a predetermined pitch calculated to achieve a desired output. For example, the core 100 in Figure 2 may include a pitch of 150 mm or more and 200 mm or less. However, this disclosure intends other non-limiting embodiments including any number of different pitches based on any number of desired outputs required by the intended application and / or user preference. Thus, multiple unit cells 102 may include various geometric variables that can be attenuated to further adjust the output of the core 100. In practice, this includes the specific geometric shape and relative location of the unit cells 102, as well as the configuration and geometric shape of the reflector 106, which can be carefully selected to adjust the output of the core 100 to meet the demands of a particular application while complying with additional requirements.

[0027] Referring here to Figure 3, a top view of a unit cell 102 of the core 100 of Figures 1 and 2 is illustrated according to at least one non-limiting aspect of the present disclosure. According to the non-limiting aspect of Figure 3, the unit cell 102 may include a plurality of fuel channels 110 configured to accommodate the fuel of the core 100 and a plurality of heat pipe channels 112 configured to accommodate the heat pipes of the core 100. Specifically, the unit cell 102 of Figure 3 includes 24 fuel channels 110 and 7 heat pipe channels 112. However, it should be understood that the unit cell 102 may include any number of fuel channels 110 and heat pipe channels 112 to optimize the generation of nuclear energy and enhance the efficiency of the removal of thermal energy from the core 100. As stated above, each unit cell 102 is configured to be self-sufficient. Therefore, each heat pipe channel 112 may be surrounded by several fuel channels 110 of the core so that the thermal energy generated by the fuel inserted into the fuel channel 110 can be effectively transferred away from the core 100. For example, the fuel may include fissile material (e.g., triploisotropic particle fuel having nuclei of uranium disilide, uranium oxide, uranium nitride, or uranium carbonite).

[0028] In other non-limiting embodiments, the unit cell 102 of Figure 3 may further include a moderator channel configured to house a moderator for the core 100 (e.g., a hydride-based moderator, such as BeO), the moderator may be configured to delay the propagation of neutrons emitted by the fuel inserted into the plurality of fuel channels 110. Alternatively and / or additionally, the unit cell 102 may include additional features configured to house other components of the core 100.

[0029] Referring further to Figure 3, the multiple fuel channels 110 may be configured to have a first diameter D1, and the multiple heat pipe channels 112 may be configured to have a second diameter D2. According to some non-limiting embodiments, the first diameter D1 and the second diameter D2 are related to providing a balance between heat generation and heat removal. This may help the unit cell 102 to be self-sufficient so that the heat pipes inserted into the heat pipe channels 112 have a larger conductive and / or convective surface area to improve their ability to transfer heat away from the core 100. Similar to the gaps G between the unit cells 102, the first diameter D1 of the fuel channels 110 and the second diameter D2 of the heat pipe channels 112 may be configured so that a desired gap exists between the fuel and the inner wall of the fuel channels 110, and between the heat pipes and the inner wall of the heat pipe channels 112, when properly inserted into the unit cells 102. Again, such gaps may be geometrically configured to optimize heat transfer throughout the entire unit cell 102 and the entire core 100. While the non-limiting embodiments of Figure 3 include channels 110, 112 having circular configurations, it should be understood that this disclosure intends other non-limiting embodiments in which channels 110, 112 having any number of geometric configurations optimize heat transfer for intended applications and user preferences. Accordingly, as used by this disclosure, the term “diameter” shall include any dimension extending away from the center point of the channels 110, 112. Thus, it should be understood that the term “diameter” is not intended to limit the channels 110, 112 to circular configurations.

[0030] Referring further to Figure 3, the unit cell 102 may also include features configured to accommodate a neutron-absorbing material that can slow down the nuclear reaction occurring in the fuel channel 110 of the unit cell 102. Thus, the power distribution and radial power peaking of the unit cell 102, and consequently the core 100 itself, can be further tuned through the influence of the neutron absorber. According to some non-limiting embodiments, the core 100 may be designed for applications that do not impose strict transport requirements on the core 100. Alternatively and / or additionally, the core 100 can use high-density fuel. According to such embodiments, the axial power peaking coefficient and axial power distribution of the unit cell 102 and the core 100 can be controlled in a different way by changing the fuel enrichment level in the fuel channel 110 of the unit cell 102, or by adding a combustible absorber.

[0031] Referring here to Figure 4A, a perspective view of the unit cell of Figure 3 is shown according to at least one non-limiting aspect of the present disclosure. According to the non-limiting aspect of Figure 4A, a plurality of unit cells 102 are configured to extend along at least a portion of the length L of the core 100. For example, each of the plurality of unit cells 102 may be modularly formed and integrated within a core block to facilitate the coherence of the core design, which represents one aspect of the coherence proposed by the design of the core 100. This may help the core 100 to conform to the output and / or size requirements associated with the intended application. In other non-limiting aspects contemplated by the present disclosure, the unit cells 102 are integrally formed along at least a portion of the length of the core 100, but may be similarly configured to achieve the desired output.

[0032] Similarly, the configuration of the reflector 106 illustrated in Figure 4B includes a plurality of reflectors 106 including a control drum 108, and the reflectors 106 are configured to extend along at least a portion of the length L of the core 100, similar to the configuration illustrated and discussed above with reference to Figure 1. Naturally, according to some non-limiting embodiments, the reflectors can also be formed integrally. Again, the reflectors can be tightly configured to create favorable gaps to promote and enhance heat transfer throughout the core 100.

[0033] Additionally and / or alternatively, according to some non-limiting embodiments, it may be advantageous for rows of unit cells 102 to overlap with rows of adjacent unit cells 102. For example, according to a non-limiting embodiment of Figure 4C, a side view of the unit cells in Figure 3 is illustrated according to at least one non-limiting embodiment of the present disclosure. As can be seen in Figure 4C, the unit cells 102 are offset from one another. Such overlap may provide the user with another geometric variable that enhances the energy generation and / or heat transfer of the entire core 100 and attenuates it to optimize the performance of the core 100 without dramatically changing the design of the core 100.

[0034] Referring now to Figure 5, a perspective view of the core 100 of Figures 1 to 4 is shown according to at least one non-limiting aspect of the present disclosure. According to the non-limiting aspect of Figure 5, the core 100 may be assembled to include fuel 111 (e.g., rods and / or stacks), heat pipes 113, and reactivity control rods 115, which are arranged throughout a plurality of unit cells 102 and reactivity control cells 108. Specifically, the fuel 111 may be arranged throughout a fuel channel 110 (Figure 3) of one or more unit cells 102, the heat pipes 113 may be arranged throughout a heat pipe channel 112 (Figure 3) of one or more unit cells 102, and the reactivity control rods 115 may be arranged through a reactivity control channel (not shown) of one or more reactivity control cells 104. According to some non-limiting aspects, the fuel 111 and heat pipes 113 are configured to extend over a predetermined length L of the core 100. In other non-limiting embodiments, the fuel 111 and heat pipe 113 extend by an additional length L' beyond a predetermined length L of the core, configured to facilitate downstream external core connections and / or equipment (e.g., power systems, condensers, structural supports). This design allows the core 100 to be customized to any intended application and / or user preference, thereby enabling the core 100 to be versatile according to customer needs. However, these modifications may be evaluated using the nuclear physics and / or manufacturability underlying the design of the core 100, maintaining reliability and predictability in the manufacture and operation of the core 100. In other words, the assembled core 100 design of Figure 5 allows the fuel 111 and heat pipe 113 to be specifically configured to adapt to any particular power requirements and / or structural configuration without having to reinvent the basic core 100 design and assume inherent development risks.

[0035] Referring further to Figure 5, the reflector 106 may further include a plurality of control drums 108 configured to house neutron-absorbing and reflecting materials. In the event of a reactor and / or power supply failure, the control drums 108 may rotate inward toward the core 100 so that the absorbing material can shut down the core 100. According to a non-limiting embodiment of Figure 5, the reflector 106 may further include a gamma shield 109 configured to substantially surround the neutron shield, the core 100, and its internal components 102, 104, 111, 113, 115 in order to further mitigate radiation.

[0036] Referring further to Figure 5, the core 100 may further include a plurality of reactivity control rods 115 configured to be positioned through one or more of a plurality of reactivity control cells 104. For example, a reactivity control cell 104 may include reactivity control rods or reactivity control channels similar to the fuel channel 110 and / or heat pipe channel 112, but is specifically configured to accommodate the reactivity control rods 115. As described above, each reactivity control rod 115 may include a neutron-absorbing material configured to slow and / or stop nuclear reactions within the core 100 in emergency situations. The reactivity control rods 115 may act collectively to prevent the core 100 from reaching critical temperature or prompt criticality in the event of a reactor and / or power supply failure. Thus, the emergence of microreactors may increase the penetration rate of nuclear technology and make safety a higher priority.

[0037] Referring here to Figure 6, a cross-sectional perspective view of the core 100 of Figures 1 to 5 is illustrated according to at least one non-limiting aspect of the present disclosure. According to the non-limiting aspect of Figure 6, the core 100 including the reflector 106 may be configured to be positioned within an external shroud 117, which may impart additional structure, shielding, and heat transfer characteristics to the core 100 depending on the intended application and / or user preference. In particular, Figure 6 illustrates how unit cells 102 and reactivity control cells 104 are arranged relative to each other to form a plurality of fuel channels 110 (Figure 3), heat pipe channels 112 (Figure 3), and reactivity control rods and / or reactivity control channels (not shown) that traverse through blocks of the core 100. The cross-sectional view illustrates the fuel 111, heat pipes 113, and reactivity control rods 115 arranged within channels 110, 112, thereby forming the functional core of the core 100. Therefore, it should be understood that the number of unit cells 102 and / or reactivity control cells 104 can be changed to adjust the output and / or geometric configuration of the core 100 without significantly altering its design.

[0038] For at least the reasons stated herein, the design of the core 100 includes adjustable outputs with a high level of manufacturability readiness. In other words, existing manufacturing techniques can be used to produce a single unit cell or a cluster of unit cells, a reflector, and / or the entire assembly disclosed herein. Thus, the core 100 can be assembled for in-process control of individual core components (e.g., unit cells, reflector segments) and may include components that are easily replaceable and / or modified as needed. These features facilitate the scalability of the core 100 and are particularly useful compared to conventional monolithic core configurations.

[0039] Referring here to Figures 7A to 9C, several stress distributions of the core 100 of Figures 1 to 6 are illustrated according to at least one non-limiting aspect of the present disclosure. For example, Figures 7A and 7B illustrate the temperature distribution of at least a portion of the core of Figures 1 to 6. As described above, the unit cells 102 may be arranged such that there is no gap G (Figure 3) between any two adjacent cells 102. The gap G (Figure 3) allows excess heat to be dissipated by the adjacent heat pipe of the adjacent unit cell 102 in the event of a heat pipe failure. For example, Figure 7A illustrates a typical temperature distribution without heat removal degradation. However, in Figure 7B, the heat pipe has failed, as indicated by the temperature concentration at point A. Since the adjacent unit cell 102 is located below the predetermined gap G from the unit cell 102 having the failed heat pipe, the excess heat can be dissipated by the adjacent heat pipe. This is evident from the heat gradient dissipation illustrated in Figure 7B. In other words, the core 100 can be tightly configured so that adjacent unit cells 102 can help dissipate heat in the event of a heat pipe failure.

[0040] Figures 8A and 8B illustrate a comparison of the stress distribution in at least a portion of the cores in Figures 1-6 with the stress distribution in a conventional monolithic core, according to at least one non-limiting aspect of this disclosure. As is evident from Figures 8A and 8B, the equivalent stress in the improved core 100 configuration in Figures 1-6 is reduced compared to the stress in a monolithic core. The stress distribution pattern is similar, but the magnitude of the stress experienced is significantly lower. Figures 9A-9C illustrate the simulated temperature and stress distribution for the cores in Figures 1-6 against the maximum expected power level, according to at least one non-limiting aspect of this disclosure. Thus, Figures 9A-9C illustrate that the overall stress experienced by the core 100 and its components is below the conventional limits for reactor operating conditions. Therefore, Figures 9A to 9C illustrate that, despite the core's output being regulated, the design of the core 100 can easily provide sufficient thermal management capabilities so that the stresses experienced by the core 100 remain in compliance with other customer requirements and / or internal and government regulations.

[0041] Referring here to Figure 10, a method 200 for adjusting the output power of a reactor core is illustrated according to at least one non-limiting aspect of the present disclosure. According to the non-limiting aspect of Figure 10, the method 200 may include adjusting the output power of a core comprising a plurality of unit cells. Each unit cell of the plurality of unit cells is configured to house fuel configured to generate energy. Furthermore, each unit cell of the plurality of unit cells is configured to house a heat pipe configured to transfer thermal energy away from the core. The initial number of unit cells in the plurality of unit cells corresponds to the initial output power of the core. For example, the initial output power may be a standardized output of the core production line, taking into account the average output desired by the customer of the production line. This can minimize the amount of adjustment required and thus reduce the amount of development and risk required to adjust the output of the core.

[0042] Referring further to Figure 10, Method 200 may include determining the amount of fuel (e.g., rods and / or stacks) based on the desired power output of the core 202. For example, the desired power output of the core may correspond to the intended use of the reactor. If the reactor will power more equipment than standard, initial production may be provided, and then the desired power output will be higher than the initial power output. Alternatively, the use may require less power, but the space or occupancy of the core may also be smaller. Therefore, the power output of the core, and thus the occupied area, should be reduced. Next, Method 200 may include determining the number of heat pipes based on predetermined requirements of the core 204. For example, the reactor may have to comply with contractual, internal, or governmental thermal requirements or safety factors. This may affect the amount of heat pipes required to maintain the desired power output in accordance with the requirements imposed on the reactor.

[0043] Referring further to Figure 10, Method 200 further includes determining the number of unit cells based on the determined amount of fuel and the determined number of heat pipes 206. In other words, the method seeks to optimize power and compliance requirements. This optimization is then integrated into the modular core design. Subsequently, the method includes mechanically modifying a plurality of unit cells so that the initial number of unit cells becomes the determined number of unit cells 208. Thus, the expandable core is modified to fit the configuration determined based on the desired output power and compliance requirements.

[0044] Various aspects of the subject matter described herein are set out in the following numbered clauses:

[0045] Article 1: An adjustable core for a nuclear reactor configured to be coupled to a reflector configured to contain a reflective material, the adjustable core comprising: a plurality of reactivity control cells, each of which includes a reactivity control rod interface configured to contain a reactivity control rod containing a neutron-absorbing material; and a plurality of unit cells, each of which includes a plurality of fuel channels configured to contain fuel, and each of which includes a plurality of heat pipe channels configured to contain heat pipes configured to transfer thermal energy away from the core, wherein each of the plurality of unit cells is positioned radially adjacent to another unit cell of the plurality of unit cells, thereby defining the radial dimension of the adjustable core, the radial dimension corresponding to a predetermined output power of the adjustable core. Section 2: The adjustable core according to Section 1, wherein each unit cell of a plurality of unit cells is oriented at a predetermined pitch relative to radially adjacent unit cells among the plurality of unit cells, and the predetermined pitch corresponds to a predetermined output power of the adjustable core. Paragraph 3: An adjustable core as described in Paragraph 1 or 2, wherein the specified pitch is 150 mm or more and 250 mm or less. Clause 4: An adjustable core according to any one of Clauses 1 to 3, wherein each unit cell of a plurality of unit cells is configured to be axially adjacent to another unit cell of the plurality of unit cells, thereby defining the length of the adjustable core, the length of which corresponds to a predetermined output power of the adjustable core. Clause 5: An adjustable core according to any of Clauses 1 to 4, wherein a plurality of unit cells are configured to accommodate additional unit cells in the radial and axial directions, thereby changing the radial and axial dimensions of the adjustable core, and changing the radial dimensions and length further changes a predetermined output power of the adjustable core. Section 6: An adjustable core as described in any of Sections 1 to 5, wherein each unit cell of a plurality of unit cells is positioned at a predetermined distance from radially adjacent unit cells of the plurality of unit cells, the predetermined distance being strictly configured such that, in the event of a failure of the first heat pipe, a second heat pipe radially adjacent to the first heat pipe compensates for the failure by transferring additional thermal energy away from the core. Clause 7: An adjustable core as described in any of Clauses 1 to 6, wherein the specified distance is 2 millimeters or less. Section 8: A tunable core as described in any of Sections 1 to 7, wherein each of the multiple heat pipe channels is substantially surrounded by at least a subset of the multiple fuel channels. Section 9: A tunable core according to any one of sections 1 to 8, wherein each of a plurality of unit cells further comprises a moderator channel configured to house a moderator configured to slow down neutrons emitted by a fuel. Clause 10: An adjustable core according to any one of Clauses 1 to 9, wherein multiple unit cells and multiple reactivity control cells are integrally formed. Clause 11: An adjustable core according to any of Clauses 1 to 10, wherein the fuel channels of each unit cell of a plurality of unit cells have a first diameter, and the heat pipe channels of each unit cell of a plurality of unit cells have a second diameter, the first and second diameters being selected such that heat generated in the plurality of fuel channels of a selected unit cell is removed by the plurality of heat pipes of a selected unit cell. Clause 12: An adjustable core according to any of Clauses 1 to 11, wherein each unit cell of a plurality of unit cells has a hexagonal configuration, and each unit cell of the plurality of unit cells is arranged such that the plurality of unit cells collectively have a hexagonal configuration. Section 13: A tunable core assembly for a nuclear reactor, the tunable core being configured to be coupled to a reflector, the tunable core assembly comprising: a plurality of reactivity control cells, each of which is configured to house a reactivity control rod comprising a neutron-absorbing material; and a plurality of unit cells, each of which is configured to house a radial dimension corresponding to the initial power output of the core, each of which is configured to house a fuel configured to generate energy, and each of which is configured to house a heat pipe configured to transfer thermal energy away from the core, wherein each of which is configured to be radially coupled to an adjacent unit cell of the plurality of unit cells, thereby changing the radial dimension, the changed radial dimension corresponding to the tunable power output of the core, and the tunable power output of the core being different from the initial power output of the core. Clause 14: The adjustable core assembly according to Clause 13, wherein each unit cell of a plurality of unit cells is oriented at a predetermined pitch relative to radially adjacent unit cells among the plurality of unit cells. Clause 15: An adjustable core assembly as described in Clause 13 or 14, wherein each unit cell of a plurality of unit cells is configured to be located at a predetermined distance from radially adjacent unit cells of the plurality of unit cells, the predetermined distance being strictly configured such that, in the event of a failure of the first heat pipe, a second heat pipe radially adjacent to the first heat pipe compensates for the failure by transferring additional thermal energy away from the core. Clause 16: An adjustable core assembly as described in any of Clauses 13 to 15, wherein the specified distance is 2 millimeters or less. Paragraph 17: A method for adjusting the output power of a reactor core, wherein the core comprises a plurality of unit cells, each unit cell of the plurality of unit cells configured to contain fuel configured to generate energy, each unit cell of the plurality of unit cells configured to contain heat pipes configured to transfer thermal energy away from the core, the initial number of unit cells in the plurality of unit cells corresponds to the initial output power of the core, the method comprising: determining an amount of fuel based at least in part on a desired output power of the core corresponding to the intended use of the reactor; determining a number of heat pipes based at least in part on a predetermined requirement of the core based at least in part on the intended use of the reactor; determining a number of unit cells based at least in part on a determined amount of fuel and a determined number of heat pipes corresponding to the determined amount of fuel and the predetermined requirement for the desired output power; and mechanically changing the plurality of unit cells so that the initial number of unit cells becomes the determined number of unit cells, thereby changing the core so that the initial output power of the core becomes a desired output power of the core. Paragraph 18: The method according to Paragraph 17, wherein the core further comprises a plurality of reactivity control cells configured to house reactivity control rods comprising a neutron-absorbing material, the method further comprising: determining a number of reactivity control rods based at least in part on a desired power output of the core and a second predetermined requirement of the core based at least in part on the intended use of the reactor; determining a number of reactivity control cells based at least in part on the determined number of reactivity control rods; and mechanically distributing the determined number of reactivity control cells across a plurality of unit cells. Paragraph 19: The method of paragraph 17 or 18, further comprising determining the gap between adjacent unit cells of a plurality of unit cells, at least in part on the thermal requirements of the core corresponding to the intended use of the reactor, and mechanically modifying the plurality of unit cells such that the distance between adjacent unit cells of the plurality of unit cells is less than or equal to the determined gap between adjacent unit cells. Paragraph 20: The method according to any of paragraphs 17 to 19, further comprising mechanically modifying a plurality of unit cells by mechanically joining an additional unit cell to an existing unit cell of a plurality of unit cells, thereby increasing the initial number of unit cells.

[0046] All patents, patent applications, publications, or other disclosures referenced herein are incorporated herein by reference in their entirety, just as each individual reference is expressly incorporated by reference. All documents and any materials, or any part thereof, that are referred to as being incorporated herein by reference are incorporated herein insofar as the incorporated material does not conflict with any existing definitions, descriptions, or other disclosures contained herein. Accordingly, the disclosures contained herein supersede, to the extent necessary, any conflicting material incorporated herein by reference, and the disclosures expressly contained herein take precedence.

[0047] The present invention has been described with reference to various exemplary and exemplary embodiments. The embodiments described herein are understood to provide exemplary features of various details of various embodiments of the disclosed invention, and therefore, unless otherwise indicated, it should be understood that, to the extent possible, one or more features, elements, components, ingredients, materials, structures, modules and / or embodiments of the disclosed embodiments may be combined, separated, replaced and / or rearranged with one or more other features, elements, components, ingredients, materials, structures, modules and / or embodiments of the disclosed embodiments without departing from the scope of the disclosed invention. Accordingly, those skilled in the art will recognize that various substitutions, modifications, or combinations are possible in any of the exemplary embodiments without departing from the scope of the invention. Furthermore, those skilled in the art will recognize, by examining this specification, many equivalents to the various embodiments of the invention described herein, or can confirm this simply by using routine experimentation. Accordingly, the present invention is limited by the claims and not by the descriptions of the various embodiments.

[0048] Those skilled in the art will generally recognize that the terms used herein, and in particular in the appended claims (e.g., the body of the appended claims), are generally intended to be “open” terms (for example, the term “includes” should be interpreted as “includes but not limited,” the term “has” should be interpreted as “at least has,” and the term “includes” should be interpreted as “includes but not limited,” etc.). If a particular number of claims to be introduced is intended, such intention will be explicitly enumerated in the claims, and if there is no such enumeration, such intention will not exist, as will be understood by those skilled in the art. For example, to aid understanding, the following appended claims may contain the use of the introductory phrases “at least one” and “one or more” to introduce an enumeration of claims. However, the use of such phrases should not be interpreted as implying that the introduction of a claim enumeration by the indefinite article “a” or “an” limits any particular claim containing such introduced claim enumeration to only one such claim, even when the same claim contains the introductory phrase “one or more” or “at least one” and an indefinite article such as “a” or “an” (for example, “a” and / or “an” should typically be interpreted as meaning “at least one” or “one or more”), and the same applies to the use of specific articles used to introduce a claim enumeration.

[0049] In addition, even if a particular number of claims enumerated is explicitly listed, a person skilled in the art will understand that such enumeration should typically be interpreted as meaning at least the number listed (for example, the literal enumeration of “two enumerations” without other modifiers means at least two enumerations, or two or more enumerations). Furthermore, in such cases where a convention similar to “at least one of A, B, and C, etc.” is used, such construction is generally intended to mean that a person skilled in the art will understand the convention (for example, “a system having at least one of A, B, and C” would not be limited to systems having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or systems having A, B, and C together, etc.). In cases where a convention similar to "at least one of A, B, or C" is used, such construction is generally intended to mean that a person skilled in the art will understand the convention (for example, "a system having at least one of A, B, or C" would not be limited to, but would include, systems having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or systems having A, B, and C together). A person skilled in the art will further understand that typical disjunctive words and / or phrases presenting two or more alternative terms in any description, claims, or drawings should be understood to intend the possibility of including one of the terms, either of the terms, or both, unless the context otherwise indicates. For example, the phrase "A or B" would typically be understood to include the possibilities of "A" or "B" or "A and B".

[0050] With regard to the attached claims, those skilled in the art will understand that the actions enumerated therein may generally be performed in any order. It should also be understood that, although the enumeration of claims is presented sequentially, various actions may be performed in other orders than those described, or simultaneously. Examples of such alternative orderings include, unless otherwise indicated by the context, repetition, alternation, interruption, reordering, increment, subordination, supplementation, simultaneous, reverse, or various other orderings. Furthermore, unless otherwise indicated by the context, terms such as “responding,” “related,” or other past tense adjectives are generally not intended to exclude such variations.

[0051] Any reference to “one aspect,” “one aspect,” “one example,” or “one example” should be noted as meaning that a particular feature, structure, or characteristic described in relation to an aspect is included in at least one aspect. Therefore, throughout this specification, the occurrences of the phrases “in one aspect,” “in one aspect,” “one example,” and “one example” in various places do not necessarily all refer to the same aspect. Furthermore, a particular feature, structure, or characteristic may be combined in any preferred manner in one or more aspects.

[0052] As used herein, unless the context explicitly indicates otherwise, the singular forms "a," "an," and "the" include plural references.

[0053] For example, but not limited to, directional expressions used herein, such as top, bottom, left, right, down, up, front, back, and variations thereof, relate to the orientation of elements shown in the accompanying drawings and do not limit the scope of the claims unless otherwise explicitly stated.

[0054] As used in this disclosure, the terms “about” or “approximately” mean, unless otherwise specified, an acceptable error in a particular value as determined by a person skilled in the art, which depends in part on how the value is measured or determined. In certain embodiments, the terms “about” or “approximately” mean within 1, 2, 3, or 4 standard deviations. In certain embodiments, the terms “about” or “approximately” mean within 50%, 200%, 105%, 100%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, or 0.05% of a given value or range.

[0055] In this specification, unless otherwise indicated, all numerical parameters should be understood, in all cases, to be prefaced and modified by the term “approximately,” meaning that the numerical parameter possesses the inherent variability characteristics of the underlying measurement technique used to determine the numerical value of the parameter. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the claims, each numerical parameter described herein should be interpreted at least in light of the reported number of significant figures and by applying common rounding techniques.

[0056] Any numerical range enumerated herein includes all subranges contained within the enumerated range. For example, the range "1 to 100" includes all subranges between the enumerated minimum value of 1 and the enumerated maximum value of 100 (including boundary values), i.e., all subranges where the minimum value is 1 or greater and the maximum value is 100 or less. Furthermore, all ranges enumerated herein include the endpoints of the enumerated range. For example, the range "1 to 100" includes the endpoints 1 and 100. Any maximum numerical limit enumerated herein is intended to include all lower numerical limits contained within the range, and any minimum numerical limit enumerated herein is intended to include all higher numerical limits contained within the range. Accordingly, the applicant reserves the right to amend this specification, including the claims, to explicitly enumerate any subranges contained within the explicitly enumerated range. All such ranges are originally described herein.

[0057] Any patent application, patent, non-patent publication, or other disclosure material referenced herein and / or enumerated in any application data sheet is incorporated herein by reference and, to that extent, is not inconsistent with the material incorporated herein. Accordingly, the disclosures contained herein supersede, to the extent necessary, any inconsistent material incorporated herein by reference. Any material, or any part thereof, that is inconsistent with existing definitions, descriptions, or other disclosure materials contained herein but is referred to as being incorporated herein by reference will be incorporated only to the extent that there is no inconsistency between the incorporated material and the existing disclosure material.

[0058] The terms “to have” (and any form of “comprise,” such as “comprises” and “comprising”), “to possess” (and any form of “have,” such as “has” and “having”), “to include” (and any form of “include,” such as “includes” and “including”), and “to contain” (and any form of “contains” and “containing”) are open-ended linking verbs. As a result, a system that “has,” “possesses,” “possesses,” or “contains” one or more elements possesses, but is not limited to possessing only, those one or more elements. Similarly, a system, apparatus, or element of apparatus that “possesses,” “possesses,” or “contains” one or more features possess, but is not limited to possessing, those one or more features.

Claims

1. An adjustable core for a nuclear reactor, configured to be coupled to a reflector configured to contain reflective material, wherein the adjustable core is A plurality of reactivity control cells, wherein each of the plurality of reactivity control cells includes a reactivity control rod interface configured to accommodate a reactivity control rod containing a neutron-absorbing material, A plurality of unit cells, each of which unit cells includes a plurality of fuel channels configured to contain fuel, each of which unit cells includes a plurality of heat pipe channels, each of which heat pipe channels is configured to contain a heat pipe configured to transfer thermal energy away from the core, and the number of fuel channels among the plurality of fuel channels is greater than the number of heat pipe channels among the plurality of heat pipe channels, An adjustable core in which each of the plurality of unit cells is arranged radially adjacent to another unit cell among the plurality of unit cells, thereby defining the radial dimension of the adjustable core, the radial dimension corresponding to a predetermined output power of the adjustable core.

2. The adjustable core according to claim 1, wherein each of the plurality of unit cells is oriented at a predetermined pitch with respect to radially adjacent unit cells among the plurality of unit cells, and the predetermined pitch corresponds to the predetermined output power of the adjustable core.

3. The adjustable core according to claim 2, wherein the predetermined pitch is 150 mm or more and 250 mm or less.

4. The adjustable core according to claim 1, wherein each of the plurality of unit cells is configured to be axially adjacent to another unit cell among the plurality of unit cells, thereby defining the length of the adjustable core, the length of which corresponds to a predetermined output power of the adjustable core.

5. The adjustable core according to claim 4, wherein the plurality of unit cells are configured to accommodate additional unit cells in the radial and axial directions, thereby changing the radial and axial dimensions of the adjustable core, and the predetermined output power of the adjustable core is further changed by changing the radial dimensions and length.

6. The adjustable core according to claim 1, wherein each of the plurality of unit cells is configured to be located at a predetermined distance from radially adjacent unit cells among the plurality of unit cells, and the predetermined distance is precisely configured such that if the first heat pipe fails, a second heat pipe radially adjacent to the first heat pipe compensates for the failure by transferring additional thermal energy away from the core.

7. The adjustable core according to claim 6, wherein the predetermined distance is 2 millimeters or less.

8. The adjustable core according to claim 1, wherein each of the plurality of heat pipe channels is substantially surrounded by at least a subset of the plurality of fuel channels.

9. The adjustable core according to claim 1, wherein each of the plurality of unit cells further comprises a moderator channel configured to house a moderator configured to slow down neutrons emitted by the fuel.

10. The adjustable core according to claim 1, wherein the plurality of unit cells and the plurality of reactivity control cells are integrally formed.

11. The adjustable core according to claim 1, wherein the fuel channel of each of the plurality of unit cells has a first diameter, and the heat pipe channel of each of the plurality of unit cells has a second diameter, the first diameter and the second diameter being selected such that heat generated in the plurality of fuel channels of the selected unit cell is removed by a plurality of heat pipes housed in the plurality of heat pipe channels of the selected unit cell.

12. The adjustable core according to claim 1, wherein each of the plurality of unit cells has a hexagonal configuration, and each of the plurality of unit cells is arranged such that the plurality of unit cells collectively have a hexagonal configuration.

13. An adjustable core assembly for a nuclear reactor, wherein the adjustable core is configured to be coupled to a reflector, and the adjustable core assembly is A plurality of reactivity control cells, wherein each of the plurality of reactivity control cells is configured to house a reactivity control rod containing a neutron-absorbing material, A plurality of unit cells, wherein each of the plurality of unit cells defines a radial dimension corresponding to the initial output power of the core, each unit cell of the plurality of unit cells includes a plurality of fuel channels configured to contain fuel configured to generate energy, each unit cell of the plurality of unit cells includes a plurality of heat pipe channels configured to contain a plurality of heat pipes configured to transfer thermal energy away from the core, and the number of fuel channels among the plurality of fuel channels is greater than the number of heat pipe channels among the plurality of heat pipe channels, An adjustable core assembly in which each of the plurality of unit cells is radially coupled to an adjacent unit cell among the plurality of unit cells, thereby changing the radial dimension, the changed radial dimension corresponding to the adjusted output power of the core, and the adjusted output power of the core is different from the initial output power of the core.

14. The adjustable core assembly according to claim 13, wherein each of the plurality of unit cells is oriented at a predetermined pitch with respect to radially adjacent unit cells among the plurality of unit cells.

15. The adjustable core assembly according to claim 13, wherein each of the plurality of unit cells is configured to be located at a predetermined distance from radially adjacent unit cells among the plurality of unit cells, the predetermined distance being precisely configured such that if the first heat pipe fails, a second heat pipe radially adjacent to the first heat pipe compensates for the failure by transferring additional thermal energy away from the core.

16. The adjustable core assembly according to claim 15, wherein the predetermined distance is 2 millimeters or less.

17. A method for adjusting the output power of a reactor core, wherein the core comprises a plurality of unit cells, each unit cell of the plurality of unit cells is configured to contain fuel configured to generate energy, each unit cell of the plurality of unit cells is configured to contain a plurality of heat pipes configured to transfer thermal energy away from the core, the initial number of unit cells in the plurality of unit cells corresponds to the initial output power of the core, and the method is: The amount of fuel is determined at least in part based on the desired power output of the core corresponding to the intended use of the reactor, Determining the number of heat pipes based at least partly on predetermined requirements of the core based at least partly on the intended use of the reactor, The process includes determining the number of unit cells based at least in part on the determined amount of fuel corresponding to the desired output power and the determined number of heat pipes corresponding to the predetermined requirements, Each unit cell includes a plurality of fuel channels and a plurality of heat pipe channels, wherein the number of fuel channels among the plurality of fuel channels is greater than the number of heat pipe channels among the plurality of heat pipe channels. The method further includes mechanically changing the plurality of unit cells such that the initial number of unit cells is the number of unit cells determined, thereby changing the core such that the initial output power of the core is the desired output power of the core.

18. The core further comprises a plurality of reactivity control cells configured to house reactivity control rods containing neutron-absorbing material, and the method is Determining the number of reactivity control rods based at least in part on the desired output power of the core and a second predetermined requirement of the core that is at least in part on the intended use of the reactor, The number of reactivity control cells is determined, at least in part, based on the number of reactivity control rods determined above. The method according to claim 17, further comprising mechanically distributing the determined number of reactivity control cells across the entire plurality of unit cells.

19. Determining the gap between adjacent unit cells among the plurality of unit cells, at least in part, based on the thermal requirements of the core corresponding to the intended use of the reactor, The method according to claim 17, further comprising mechanically changing the plurality of unit cells such that the distance between adjacent unit cells is less than or equal to the determined gap between adjacent unit cells.

20. The method according to claim 17, further comprising mechanically changing the plurality of unit cells by mechanically combining additional unit cells with existing unit cells of the plurality of unit cells, thereby increasing the initial number of unit cells.

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