Metal hydride fuel burn-up self-sustaining reactor core controlled by burnable poison

Abstract

A metal hydride fuel burn-up self-sustaining reactor core controlled by burnable poison relates to the technical field of nuclear reactor cores, and comprises a low-enrichment-degree control rod-free fuel assembly located in the center of the reactor core, and a middle-enrichment-degree control rod-free fuel assembly arranged around the periphery of the low-enrichment-degree control rod-free fuel assembly. A middle-enrichment-degree safety rod-containing fuel assembly is arranged between the fuel tank and the fuel tank; a high-enrichment-degree control rod-free fuel assembly is arranged around the periphery of the medium-enrichment-degree control rod-free fuel assembly, and a medium-enrichment-degree compensation adjusting rod-containing fuel assembly is arranged between the medium-enrichment-degree control rod-free fuel assembly and the high-enrichment-degree control rod-free The periphery of the high-enrichment-degree control rod-free fuel assembly is filled with lead bismuth; the reactor core is used for solving the problem that a traditional reactor core is difficult to reach expected burnup depth and even causes short service life.

Description

Technical Field

[0001] This invention relates to the field of nuclear reactor core technology, and more specifically to a self-sustaining reactor core using combustible poison-controlled metal hydride fuel burnup. Background Technology

[0002] One of the core objectives of nuclear reactor core design is to achieve precise and long-term control of reactivity. This ensures that the core possesses sufficient initial reactivity to sustain the chain reaction throughout its operational lifespan, while also controlling residual reactivity at a reasonable level to guarantee operational safety and economy. To this end, core design typically incorporates reactivity control devices such as control rods and burnt poisons. Burnt poisons, through their characteristic of "burning" as burnup progresses, provide a crucial technical pathway for compensating for residual reactivity at the beginning of the lifespan and smoothing out power distribution.

[0003] In conventional fast neutron spectrum reactors using metal coolants (such as lead and lead-bismuth alloys), the core design typically lacks moderators to achieve higher breed ratios or smaller volumes, resulting in a "hard" neutron spectrum (i.e., dominated by fast neutrons). While this fast-spectrum environment offers the aforementioned advantages, it also presents fundamental challenges to reactivity control, particularly the application of combustible poisons. Traditionally highly efficient combustible poison materials, such as boron-10 (found in B4C), gadolinium (Gd₂O₃), erbium (Er₂O₃), hafnium (Hf), and europium (Eu₂O₃), exhibit a significant decrease in their microscopic neutron absorption cross-section with increasing neutron energy. Under fast-spectrum conditions, the absorption cross-section of these materials is generally very small.

[0004] This physical characteristic leads to two main problems: First, to suppress sufficient residual reactivity at the beginning of the reactor's lifespan, a large amount of combustible poison must be loaded into the core. Second, and more importantly, due to the small absorption cross-section, the consumption (burn-off) rate of these poisons during core operation is very slow and cannot match the consumption of fissile nuclides. As a result, by the end of the reactor's lifespan, a large amount of combustible poison remains in the core. This residual poison continues to absorb neutrons, causing a significant "reactivity penalty," which not only reduces fuel utilization efficiency but may also make it difficult for the core to reach the expected burn-off depth, even affecting the length of the reactor's lifespan. Therefore, in traditional metal-cooled fast reactors, combustible poison is usually avoided or used only in very small quantities to control residual reactivity, instead relying excessively on movable control rod systems. This undoubtedly increases the design burden and operational complexity of the control rods and limits further improvements in core performance.

[0005] Therefore, we propose a reactor core that can ensure the reactor core reaches the expected burn-up depth and extend its service life. Summary of the Invention

[0006] The purpose of this invention is to provide a self-sustaining reactor core using combustible poison-controlled metal hydride fuel burnup, which solves the problem that traditional reactor cores are difficult to achieve the expected burnup depth, and even lead to a short lifespan.

[0007] This invention is achieved through the following technical solution: A self-sustaining reactor core using combustible poison-controlled metal hydride fuel burnup includes low-enrichment fuel assemblies without control rods, medium-enrichment fuel assemblies without control rods, medium-enrichment fuel assemblies with safety rods, medium-enrichment fuel assemblies with compensation and regulation rods, high-enrichment fuel assemblies without control rods, and lead and bismuth. The low-enrichment, controlless fuel assembly is located at the center of the reactor core. A medium-enrichment, controlless fuel assembly is arranged around the low-enrichment, controlless fuel assembly, and a medium-enrichment, safety rod-containing fuel assembly is arranged between the two. The high-enrichment fuel assembly without control rods is arranged around the medium-enrichment fuel assembly without control rods, and a medium-enrichment fuel assembly with compensation and adjustment rods is arranged between the two. The periphery of the high-enrichment, control rod-less fuel assembly is filled with lead-bismuth.

[0008] Furthermore, the fuel enrichment of the low-enrichment fuel assembly without control rod is 22%, the fuel enrichment of the medium-enrichment fuel assembly with safety rod, the medium-enrichment fuel assembly with safety rod, and the medium-enrichment fuel assembly with compensation regulating rod is 25%, and the fuel enrichment of the high-enrichment fuel assembly without control rod is 29%.

[0009] Furthermore, the low-enrichment, medium-enrichment, and high-enrichment fuel assemblies without control rods all consist of a fuel rod, a combustible poison rod, an assembly box, and lead-bismuth from the inside out.

[0010] Furthermore, the structure of the medium-enriched fuel assembly containing a safety rod consists of a safety rod, a fuel rod, a combustible poison rod, an assembly box, and lead and bismuth from the inside out. The safety bar is made of It consists of a core, helium, a stainless steel cladding, air, control rods, guide rods, and lead-bismuth.

[0011] Furthermore, the structure of the medium-enrichment fuel assembly with compensation and adjustment rod consists of, from the inside out, a compensation and adjustment rod, a fuel rod, a combustible poison rod, an assembly box, and lead and bismuth. The compensation adjusting rod has a structure consisting of, from the inside out, counterweights made of tungsten and helium, a stainless steel cladding, and more helium. It consists of a core, helium gas, a stainless steel cladding, lead and bismuth, a control rod guide tube, and lead and bismuth.

[0012] Furthermore, the structure of the fuel rod consists of a fuel core, helium gas, a stainless steel cladding, and lead-bismuth from the inside out. The structure of the combustible poison rod consists of an inner neutron absorber, helium, a stainless steel cladding, and lead-bismuth, arranged from the inside out.

[0013] Furthermore, the fuel type within the fuel core is... Furthermore, the mass ratio of uranium can be adjusted within the range of 10%-45%.

[0014] Furthermore, in the safety bar The B-10 content in the core is 90%, and the compensation adjustment rod contains... The B-10 content in the core is 30%.

[0015] Furthermore, the effective density range of the combustible poison in the neutron absorber is 0.1. -2.6 .

[0016] Furthermore, the effective density of the flammable poison in the neutron absorber can be changed by cavitation or density compaction; or by combining it with materials that have no neutron absorption properties to achieve density range adjustment.

[0017] The technical solution of the present invention has at least the following advantages and beneficial effects: This invention discloses a self-sustaining metal hydride fuel burnup reactor core controlled by combustible poisons. The core utilizes fuel rods within all fuel assemblies to create a softened energy spectrum environment. Combined with the refined combustible poison rods within all fuel assemblies, this integrated structure significantly increases the neutron absorption cross-section of the combustible poison material. This allows for the achievement of the desired initial reactivity control effect with only a relatively small amount of poison. Simultaneously, the burnup rate of the poison is significantly accelerated, better matching the core's power lifespan and achieving the expected burnup depth. This substantially reduces poison residue and corresponding reactivity penalties at the end of the reactor's lifespan, enabling smooth and automatic compensation for residual reactivity from the beginning to the end of the reactor's lifespan.

[0018] In addition, by doping and adjusting the effective density, as well as matching the abundance of B-10, the combustion curve of each poison can be precisely programmed, thereby further ensuring that the reactor core can reach the expected burn-up depth. This directly means higher uranium resource utilization, fewer refueling times, and lower post-refueling waste disposal costs, resulting in significant economic benefits.

[0019] Furthermore, low-enriched fuel assemblies, medium-enriched fuel assemblies with safety rods, medium-enriched fuel assemblies with safety rods, medium-enriched fuel assemblies with compensating control rods, and high-enriched fuel assemblies together constitute radial fuel enrichment zones. This not only flattens the reactor core's power but also, combined with the softened energy spectrum, creates differentiated neutron environments in different regions of the core. This allows the poison to burn up more quickly in the central region and has a longer duration of action in the peripheral region. This spatially differentiated control further optimizes the reactivity distribution of the entire core. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a self-sustaining metal hydride fuel burnup reactor core structure using combustible poison control according to the present invention. Figure 2 This is a schematic diagram of the structure of the control rod-less fuel assembly of the present invention; Figure 3 This is a schematic diagram of the structure of the fuel assembly containing the safety rod of the present invention; Figure 4 This is a schematic diagram of the fuel assembly with compensation regulating rod of the present invention; Figure 5 This is a schematic diagram of the structure of the safety bar of the present invention; Figure 6 This is a schematic diagram of the structure of the compensation adjusting rod of the present invention; Figure 7 This is a schematic diagram of the structure of the fuel rod of the present invention; Figure 8 This is a schematic diagram of the structure of the combustible poison rod of the present invention.

[0021] The following are included: 1. Low-enrichment fuel assembly without control rods; 2. Medium-enrichment fuel assembly without control rods; 3. Medium-enrichment fuel assembly with safety rods; 4. Medium-enrichment fuel assembly with compensation and adjustment rods; 5. High-enrichment fuel assembly without control rods; 6. Lead and bismuth; 7. Fuel rods; 8. Combustible poison rods; 9. Assembly box; 10. Safety rods; 11. Compensation and adjustment rods; 12. 13. Core; 14. Helium; 15. Stainless steel cladding; 16. Air; 17. Control rod guide tube; 18. Tungsten counterweight; 19. Fuel core; 10. Neutron absorber. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Example 1 A self-sustaining reactor core using combustible poison-controlled metal hydride fuel burnup includes a low-enrichment fuel assembly without control rods 1, a medium-enrichment fuel assembly with safety rods 3, a medium-enrichment fuel assembly with safety rods 3, a medium-enrichment fuel assembly with compensation and regulation rods 4, a high-enrichment fuel assembly without control rods 5, and lead-bismuth 6. Specifically, the fuel enrichment of the low-enrichment fuel assembly without control rod 1 is 22%, the fuel enrichment of the medium-enrichment fuel assembly without control rod 2, the medium-enrichment fuel assembly with safety rod 3, and the medium-enrichment fuel assembly with compensation regulating rod 4 is 25%, and the fuel enrichment of the high-enrichment fuel assembly without control rod 5 is 29%. In a cylindrical reactor core, the neutron flux density naturally exhibits a distribution that is high at the center and low at the edges. If left uncontrolled, this can lead to excessively high power at the center, forming a "power peak." Therefore, by loading fuel with a 22% enrichment level in the central region, the nuclear reaction rate in the central region can be suppressed. At the same time, loading fuel with a 29% enrichment level in the peripheral region can compensate for the reactivity loss caused by neutron leakage and increase the power in the peripheral region. This structure, by forming radial fuel enrichment zones, effectively flattens the power distribution of the reactor core, avoids local overheating, and allows the overall power of the reactor core to be safely increased. Furthermore, combined with the softened energy spectrum, it creates differentiated neutron environments in different regions of the reactor core. This allows the poison to burn up more quickly in the central region and to act for a longer time in the outer region. This spatially differentiated control further optimizes the reactivity distribution of the entire reactor core. The low-enrichment fuel assembly without control rods 1 is located at the center of the reactor core. The low-enrichment fuel assembly without control rods 1 is surrounded by a medium-enrichment fuel assembly without control rods 2, and a medium-enrichment fuel assembly with safety rods 3 is disposed between the two. The high enrichment fuel assembly without control rod 2 is arranged around the periphery of the medium enrichment fuel assembly without control rod 5, and a medium enrichment fuel assembly with compensation regulating rod 4 is arranged between the two. The periphery of the high-enrichment, control rod-free fuel assembly 5 is filled with lead-bismuth 6; This is a nested, functionally partitioned layout strategy; the central area contains low-enrichment fuel to suppress power peaks; the middle area contains the main medium-enrichment fuel and safety rods 10 that perform emergency shutdown functions; the outer area contains high-enrichment fuel and compensation / regulation rods for fine-tuning; and the outermost lead-bismuth 6 acts as a neutron reflector.

[0024] This arrangement optimizes the core power distribution. The lead-bismuth 6 reflector layer can reflect leaked neutrons back to the active region, improving neutron utilization and helping to reduce core size or extend lifespan. The control rods are arranged in functional safety / compensation adjustment zones, which meets safety requirements such as shutdown depth and sticking criteria, and achieves operational control flexibility.

[0025] In addition, as attached Figure 2 As shown, the low-enrichment, controlless fuel assembly 1, the medium-enrichment, controlless fuel assembly 2, and the high-enrichment, controlless fuel assembly 5 are all composed of a fuel rod 7, a combustible poison rod 8, an assembly box 9, and a lead-bismuth 6 from the inside out. Among them, the metal hydride in fuel rod 7 While providing fission fuel, the hydrogen atoms in its lattice act as moderators, softening the core energy spectrum. Meanwhile, the combustible poison rods 8 are responsible for absorbing excess initial reactivity under the softened energy spectrum and releasing it smoothly with burnup. Furthermore, all the uncontrolled rod assemblies together constitute the basic environment for softening the energy spectrum and the execution system for implementing full-lifetime reactivity compensation. The assembly box 9 ensures the structural integrity of the assembly, while the lead-bismuth 6 coolant flows between the rod bundles, carrying away the fission heat.

[0026] like Figure 3 As shown, the structure of the medium-enriched fuel assembly 3 containing a safety rod consists of a safety rod 10, a fuel rod 7, a combustible poison rod 8, an assembly box 9, and lead-bismuth 6, from the inside out. Among them, such as Figure 4 As shown, safety bar 10 is made of It consists of a core 12, helium gas 13, stainless steel cladding 14, air 15, control rod guide tube 16, and lead-bismuth 6. Furthermore, safety rod 10 is a negative reactive introduction device specifically designed for emergency shutdown, and its core... The core 12 has an absorber with high neutron absorption capacity, and the air gap 15 in the guide tube is a coolant channel, which can effectively reduce the resistance when the control rod moves. In addition, the fuel assembly provides regional power while integrating a fast shutdown function. In an emergency, the safety rod 10 is quickly inserted into the core by gravity. Its huge reactivity value can quickly terminate the chain reaction and is the last barrier for core safety.

[0027] like Figure 5 As shown, the structure of the medium enrichment fuel assembly 4 with compensation regulating rod is composed of compensation regulating rod 11, fuel rod 7, combustible poison rod 8, assembly box 9 and lead-bismuth 6 from the inside out; Among them, such as Figure 6 As shown, the structure of the compensation adjusting rod 11 consists of, from the inside out, a counterweight tungsten 17, helium gas 13, a stainless steel cladding 14, and helium gas 13. The structure consists of a core 12, helium gas 13, a stainless steel cladding 14, lead-bismuth gas 6, a control rod guide tube 16, and lead-bismuth gas 6; the counterweight tungsten 17, helium gas 13, and stainless steel cladding 14 constitute the compensation rod structure. The core 12, helium gas 13, and stainless steel shell 14 constitute the regulating rod structure; The compensation adjustment rod 11 is used for precise daily responsive control, while the counterweight tungsten 17 is used to balance buoyancy and gravity, ensuring that the drive mechanism can accurately control its position. Core 12 typically employs a lower B-10 enrichment to reduce the value of a single rod and meet the rod jamming criterion. This fuel assembly enables precise management of operational reactivity, with compensating rods used for slow boosting to compensate for the decrease in reactivity caused by fuel consumption, and regulating rods used for fine-tuning to cope with power fluctuations. The complex structural design ensures the accuracy and safety of its operation.

[0028] like Figure 7 As shown, the structure of the fuel rod 7 consists of a fuel core 18, helium gas 13, stainless steel cladding 14, and lead-bismuth 6 from the inside out. like Figure 8 As shown, the structure of the combustible poison rod 8 consists of a neutron absorber 19, helium gas 13, a stainless steel shell 14, and lead-bismuth 6 from the inside out. Fuel rod 7 and combustible poison rod 8 are general-purpose rods. Helium 13 is used as a binding gas to contain the fission gas released after the fuel or poison is irradiated, and to prevent the internal pressure of the cladding 14 from being too high. The stainless steel cladding 14 is the first safety barrier, which isolates the radioactive material from the coolant.

[0029] It is important to note that Figures 1-8 The colors are used to distinguish different structures.

[0030] The total number of fuel assemblies is 85, and their distribution structure is as follows: Figure 1 The reactor consists of 13 low-enrichment fuel assemblies without control rods (1), 24 medium-enrichment fuel assemblies without control rods (2), 6 medium-enrichment fuel assemblies with safety rods (3), 12 medium-enrichment fuel assemblies with compensation and adjustment rods (4), and 30 high-enrichment fuel assemblies without control rods (5). The active zone, comprised of all fuel assemblies and lead-bismuth (6), has an equivalent diameter of 199 cm and an active zone height of 160 cm, resulting in a core height-to-diameter ratio of 0.8. This compact design helps reduce the core volume and increase the power density, achieving a core power density of 60 kW / cm². The virtual initial uranium loading was 5.12t, and the average burnup depth at the end of the life was 58Wd / tU. This constituted an advanced reactor core with high performance, long life, and high burnup. It proved that the present invention can successfully solve the problems of shallow burnup and short life of traditional fast reactors by combining metal hydride fuel with refined combustible poison.

[0031] In addition, six medium-enrichment fuel assemblies 3 with safety rods are evenly surrounded around the low-enrichment fuel assembly 1 without control rods, and twelve medium-enrichment fuel assemblies 4 with compensation and adjustment rods are evenly surrounded around the medium-enrichment fuel assembly 2 without control rods. Both the safety rod 10 and the compensation and adjustment rod 11 can be extracted or inserted by the corresponding drive mechanism, which makes them easy to replace. In all fuel assemblies, the fuel rod 7 core 12 has a radius of 0.40 cm, the stainless steel cladding 14 has an inner diameter of 0.41 cm and an outer diameter of 0.47 cm, the center distance of the fuel rods 7 is 1.09 cm, and the grid pitch-to-rod diameter ratio is 1.16. In fuel assemblies without control rods with low, medium, and high enrichment, the number of inner fuel rods 7 is 11. In fuel assemblies with control rods, the number of inner fuel rods 7 is 7. The control rod occupies 4 rod positions. The number of fuel rods 7 in fuel assemblies without control rods and fuel assemblies with control rods are 312 and 270, respectively. In all fuel assemblies, the inner side-to-side distance of assembly box 9 is 20.00cm, the outer side-to-side distance is 20.40cm, the center distance of the assemblies is 20.60cm, and the outer side-to-side distance of control rod guide tube 16 is 6.5cm, with an inner radius of 2.75cm.

[0032] Example 2 As one embodiment, the fuel type within the fuel core 18 is... Furthermore, the uranium mass ratio can be adjusted within a range of 10%-45%, and in this embodiment, the uranium mass ratio is specifically adjusted within a range of 35%. The proportion of uranium in the metal hydride fuel is a key valve for adjusting the "softness" and "hardness" of the core energy spectrum. Reducing the uranium proportion is equivalent to increasing the hydrogen / uranium atomic ratio, which enhances the moderation capability and makes the energy spectrum softer; increasing the uranium proportion makes the energy spectrum harder. Moreover, the uranium mass within this adjustment range can achieve a hyperthermal neutron energy spectrum, creating the best working environment for combustible poisons. The adjustable uranium mass ratio gives the core design great flexibility, allowing the energy spectrum to be optimized by adjusting a single parameter, thereby precisely matching the burnup characteristics of different combustible poisons. For all 8 types of flammable poison rods The doping composition used is specifically 40% Zr and naturally abundant Zr. mix, The equivalent density is 1.2. ,Will Mixing with 40% Zr is a physical "dilution" process. By adding Zr structural material without neutron absorption, the effective density of B-10 nuclei per unit volume is reduced. This process allows engineers to precisely set the initial reactivity value and consumption rate of the poison rods, just like "programming," to ensure that its burnup curve perfectly matches the 1000 EFPD lifespan of the reactor core, avoiding excessive suppression at the beginning of the lifespan or excessive residue at the end of the lifespan.

[0033] In addition, the safety bar 10 The B-10 content in the core 12 is 90%, and the compensation adjustment rod 11 contains... The B-10 content in the core 12 is 30%; the total value of the safety rods 10 is 7132 pcm, meaning that if all the safety rods 10 are fully inserted into the core, they can reduce the reactivity of the core by a total of 7132 pcm. The value of the 12 sets of compensation and adjustment rods 11 is 16887 pcm, which is the same as the total value of the safety rods 10. The average value of a single bundle of compensation rods and adjustment rods is lower than the core delayed neutron fraction of 720 pcm, which is also the same as the total value of the safety rods 10. At the same time, the core reactivity control rods meet the design requirements for shutdown depth and sticking rods. This is a refined design tailored to the different functional requirements of the control rods. High-enriched B-10 is used to maximize its neutron absorption capacity per unit volume, ensuring the rapid introduction of significant negative reactivity in emergency situations. Conversely, low-enriched B-10 or natural B-10 is used. Core 12 significantly reduces the value of a single rod, ensuring that the average value of a single bundle of compensation / adjustment rods is lower than the core's delayed neutron fraction of 720 pcm. This strictly adheres to the rod-clamping criterion, preventing instantaneous criticality accidents even if the most valuable bundle of rods is inserted uncontrollably, thus greatly improving operational safety.

[0034] When the safety rod 10 and the compensation regulating rod 11 are extracted by the drive mechanism, the core rod extraction procedure will control the drive mechanism to perform the following extraction methods: full extraction of the safety rod 10, raising the regulating rod to half the core height, and raising the compensation rod to the core criticality. During the burnup process, the compensation rod is raised to compensate for the burnup reactivity loss, and the regulating rod does not need to compensate for the reactivity requirements of the rise and fall power and the short-term reaction disturbance compensation. This is a hierarchical and coordinated control strategy. The safety rod 10 is fully raised to ensure that it can fall rapidly by gravity at any time after receiving a signal. It is a dedicated safety facility and does not participate in regulation during normal operation. The regulating rod half-height standby enables it to have the ability to adjust up or down in both directions to respond quickly to power changes. The compensation rod is used for criticality and burnup compensation. Its raising process directly corresponds to the core from start-up to operation, and the residual reactivity that is gradually released as burnup deepens. This program clearly defines the roles of different control rods, achieving a balance between safety and operational flexibility. It automates and predicts reactivity control throughout the reactor core's lifespan, minimizing operator intervention and providing crucial operational assurance for maintaining stable reactivity fluctuations within 200 pcm throughout the entire lifespan.

[0035] Example 3 As one embodiment, the flammable poison in the neutron absorber 19 can be a conventionally used flammable poison, such as... , , Hf , The substances include Ag, In, and Cd, among which the effective density range of flammable toxic substances is 0.1. -2.6 .

[0036] Furthermore, the flammable poison in the neutron absorber 19 can be used to change its effective density by cavitation or density compaction; or it can be combined with materials that have no neutron absorption properties to adjust the density range, specifically the aforementioned 0.1. -2.6 ; It is important to note that when combining materials with neutron-free absorption properties, the use of flammable toxic substances may be problematic. It can be combined with Zr structural materials to adjust the effective density range of flammable poisons. , , or , can be with By combining C materials, the effective density range of flammable toxic substances can be adjusted; The specific doping processes applicable to different toxic materials have been clarified, making density adjustment, a key design method, feasible and operable for engineering implementation. Furthermore, in this embodiment, the type and parameters of combustible poison can be adjusted according to parameters such as core power density and lifespan to match the rate of combustible poison consumption with the core power lifespan; specifically: For reactors with high power density and long lifespan cores, the following options can be selected: Hf or As combustible poisons, these elements are known for their high resonance absorption integrals. Resonance absorption has a strong self-shielding effect, causing the poison rods to burn slowly from the outside in, with a gradual and sustained consumption rate. For short-life reactor cores, these elements are selected... or As combustible poisons, these two elements have extremely large thermal neutron absorption cross sections, and they are rapidly consumed in the softened energy spectrum. At the same time, they are doped and their effective density is adjusted according to power density and lifetime. This establishes a mapping relationship between "toxic substance characteristics and core requirements," allowing engineers to quickly select the most suitable toxic substance for cores with any target lifespan and power level, fundamentally ensuring that the consumption rate of combustible toxic substances matches the core burnup requirements.

[0037] In addition to traditional combustible poisons, transplutonium can be used as a combustible poison. At the beginning of the reactor's lifespan, transplutonium isotopes can be used as poisons. During the lifespan, after absorbing neutrons, they are gradually converted into fissile nuclides. As the reactor core burns up, the reactivity of the reactor core is gradually improved, which can make up for the reactivity loss due to the burnup of fissile nuclides. Because transplutonium is a strong neutron absorber at the beginning of its lifespan, acting as a poison, it undergoes transmutation after absorbing neutrons, transforming into fissile nuclides. Therefore, during its lifespan, transplutonium not only consumes itself but also generates new fissile fuel, dynamically compensating for the decrease in reactivity caused by the burnup of fissile nuclides, and even improving the reactivity of the reactor core.

[0038] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A self-sustaining reactor core using combustible poison-controlled metal hydride fuel burnup, characterized in that, Including low-enrichment fuel assemblies without control rods (1), medium-enrichment fuel assemblies with safety rods (3), medium-enrichment fuel assemblies with safety rods (3), medium-enrichment fuel assemblies with compensation and regulation rods (4), high-enrichment fuel assemblies without control rods (5), and lead-bismuth (6). The low-enrichment, controlless fuel assembly (1) is located at the center of the reactor core. The low-enrichment, controlless fuel assembly (1) is surrounded by a medium-enrichment, controlless fuel assembly (2), and a medium-enrichment, safety rod fuel assembly (3) is arranged between the two. The high enrichment fuel assembly without control rod (5) is arranged around the medium enrichment fuel assembly without control rod (2), and a medium enrichment fuel assembly with compensation regulating rod (4) is arranged between the two. The periphery of the high-enrichment, control rod-free fuel assembly (5) is filled with lead bismuth (6).

2. The self-sustaining metal hydride fuel burnup reactor core according to claim 1, characterized in that: The fuel enrichment of the low-enrichment fuel assembly without control rod (1) is 22%, the fuel enrichment of the medium-enrichment fuel assembly without control rod (2), the fuel enrichment of the medium-enrichment fuel assembly with safety rod (3) and the fuel enrichment of the medium-enrichment fuel assembly with compensation regulating rod (4) is 25%, and the fuel enrichment of the high-enrichment fuel assembly without control rod (5) is 29%.

3. The self-sustaining metal hydride fuel burnup reactor core according to claim 1, characterized in that: The low-enrichment, controlless fuel assembly (1), the medium-enrichment, controlless fuel assembly (2), and the high-enrichment, controlless fuel assembly (5) are all composed of fuel rods (7), combustible poison rods (8), assembly boxes (9), and lead-bismuth (6) from the inside out.

4. The self-sustaining metal hydride fuel burnup reactor core according to claim 1, characterized in that: The structure of the medium enrichment fuel assembly (3) containing a safety rod consists of a safety rod (10), a fuel rod (7), a combustible poison rod (8), an assembly box (9), and lead-bismuth (6) from the inside out. The safety bar (10) has a structure that extends from the inside out. It consists of a core (12), helium (13), a stainless steel cladding (14), air (15), a control rod guide tube (16), and lead-bismuth (6).

5. The self-sustaining metal hydride fuel burnup reactor core according to claim 1, characterized in that: The structure of the medium enrichment fuel assembly (4) with compensation and adjustment rod is composed of compensation and adjustment rod (11), fuel rod (7), combustible poison rod (8), assembly box (9) and lead-bismuth (6) from the inside out; The structure of the compensation adjustment rod (11) consists of, from the inside out, counterweight tungsten (17), helium (13), stainless steel cladding (14), and helium (13). It consists of a core (12), helium (13), stainless steel cladding (14), lead-bismuth (6), control rod guide tube (16) and lead-bismuth (6).

6. The self-sustaining metal hydride fuel burnup reactor core according to any one of claims 3-5, characterized in that: The structure of the fuel rod (7) consists of a fuel core (18), helium (13), stainless steel cladding (14), and lead-bismuth (6) from the inside out. The structure of the combustible poison rod (8) consists of a neutron absorber (19), helium (13), a stainless steel shell (14), and lead-bismuth (6) from the inside out.

7. The self-sustaining metal hydride fuel burnup reactor core according to claim 6, characterized in that: The fuel type inside the fuel core (18) is Furthermore, the mass ratio of uranium can be adjusted within the range of 10%-45%.

8. The self-sustaining metal hydride fuel burnup reactor core according to any one of claims 4-5, characterized in that: In the safety bar (10) The B-10 content in the core (12) is 90%, and the compensation adjustment rod (11) contains... The B-10 content in the core (12) is 30%.

9. The self-sustaining metal hydride fuel burnup reactor core according to claim 6, characterized in that: The effective density range of the combustible poison in the neutron absorber (19) is 0.

1. -2.6 .

10. The self-sustaining metal hydride fuel burnup reactor core according to claim 9, characterized in that: The combustible poison in the neutron absorber (19) is used to change the effective density by cavitation or density compaction; or by combining it with materials that have no neutron absorption properties to achieve density range adjustment.

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