Reactor core with mixed arrangement of metal hydride fuel and metal fuel

Abstract

The invention relates to the technical field of nuclear reactor cores, and particularly provides a reactor core with mixed arrangement of metal hydride fuel and metal fuel, which comprises a plurality of fuel assemblies, any fuel assembly comprises a metal hydride fuel rod loaded with metal hydride fuel and a metal fuel rod loaded with metal fuel; and in any one of the fuel assemblies, the proportion of the metal hydride fuel rods is 0-100%. The high uranium density and high proliferation characteristics of metal fuel and the hydrogen atom moderation characteristic of metal hydride fuel are utilized, the metal fuel and the metal hydride fuel are arranged in a mixed mode, meanwhile, the proportion of the metal hydride fuel and the metal fuel is adjusted according to the reactor core power life period and other design requirements, and customized adjustment of the reactor core energy spectrum is achieved; and the performance of the reactor core is optimized to meet the requirements of different application scenes.

Description

Technical Field

[0001] This invention relates to the field of nuclear reactor core technology, and more specifically, to a reactor core in which metal hydride fuel and metal fuel are mixed and arranged. Background Technology

[0002] In nuclear reactor core design, the neutron energy spectrum is one of the key parameters that determine the core performance. Fast-spectrum reactor cores, which do not contain moderators, have a spectrum dominated by fast neutrons, forming typical fast-spectrum characteristics. In contrast, traditional pressurized water reactors, boiling water reactors, and other thermal-spectrum reactor cores rely on moderators such as light water and heavy water to moderate neutrons into thermal neutrons, and their core energy spectra exhibit thermal-spectrum characteristics.

[0003] Fast-spectrum reactor cores typically possess larger critical masses and greater breeding capabilities, while thermal-spectrum reactor cores have larger fission cross-sections, resulting in smaller critical masses but generally weaker breeding capabilities. Specifically, on one hand, the interaction cross-section between fast neutrons and fissile nuclides is smaller, requiring more fissile nuclides to maintain the chain reaction, thus leading to a larger critical mass. On the other hand, fast neutrons are more easily absorbed by fissile nuclides and converted into fissile nuclides, exhibiting significant breeding potential. In contrast, thermal-spectrum reactor cores have significantly larger interaction cross-sections between thermal neutrons and fissile nuclides; a small number of fissile nuclides are sufficient to meet the criticality conditions, resulting in a smaller critical mass. However, thermal neutrons are less effectively absorbed by fissile nuclides, leading to a weaker overall breeding capability for the reactor core.

[0004] From the perspective of nuclide reaction characteristics, the fission cross-section of fissile nuclides (such as U-235 and Pu-239) exhibits a clear energy spectrum dependence—the fission cross-section is extremely large in the thermal neutron region, while it decreases significantly in the fast neutron region. The neutron absorption and conversion characteristics of fissile nuclides (such as U-238) are completely opposite; the reaction cross-section for absorbing neutrons and converting to fissile nuclides is at a high level in the fast neutron region, but almost zero in the thermal neutron region. This energy spectrum dependence of nuclide reactions directly translates into quantitative differences in reactor core performance: for the same amount of U-235 or Pu-239, a softer core energy spectrum results in higher fissile nuclide fission efficiency and greater reactivity in the core; while for the same amount of U-238, a harder core energy spectrum results in higher conversion efficiency to fissile nuclides and a larger conversion ratio in the core.

[0005] In current nuclear reactor design, different application scenarios have diverse requirements for core performance: scenarios such as military power reactors and advanced breeder reactors require priority to ensure high breeder capability, relying on hard spectrum characteristics; while scenarios such as civilian power reactors and small modular reactors place greater emphasis on reactivity stability and criticality safety, requiring higher soft spectrum characteristics. Therefore, how to break through the inherent constraints of the core energy spectrum and achieve flexible adjustment of the energy spectrum to match diverse needs has become a technical challenge that urgently needs to be overcome in the field of nuclear reactor core design. Summary of the Invention

[0006] To address the aforementioned shortcomings in the existing technology, the core objective of this invention is to provide a reactor core with a mixed arrangement of metal hydride fuel and metal fuel, applicable to lead-bismuth power reactors. This invention utilizes the high uranium density and high multiplication characteristics of metal fuel, as well as the hydrogen atom moderation characteristics of metal hydride fuel, to mix and arrange the metal fuel and metal hydride fuel. Furthermore, the ratio of metal hydride fuel to metal fuel can be adjusted according to the core power lifetime and other design requirements, enabling customized adjustment of the core energy spectrum and optimizing core performance to adapt to different application scenarios.

[0007] This invention is achieved through the following technical solution: A reactor core with a mixture of metal hydride fuel and metal fuel includes several fuel assemblies; each fuel assembly includes a metal hydride fuel rod loaded with metal hydride fuel and a metal fuel rod loaded with metal fuel; the proportion of the metal hydride fuel rod is 0-100%.

[0008] Metal hydride fuels contain moderator hydrogen atoms within the fuel. For metal hydride fuels such as zirconium uranium hydride, fast neutrons in the reactor core collide with hydrogen atoms bound in the zirconium lattice and... Neutrons are thermally heated by exchanging energy in integer multiples of eV. For neutrons with energies below 0.137 eV, further thermalization in zirconium hydride is difficult, except in other types of moderators. Simultaneously, neutrons in zirconium hydride may also gain one or more units of energy from excited oscillators during scattering, and the number of excited oscillators in the zirconium hydride lattice increases with increasing fuel temperature. When reactor power suddenly increases and fuel temperature rises immediately, the proportion of hydrogen atoms in higher excited states increases, increasing the probability of neutrons gaining energy through collisions with hydrogen nuclei in zirconium hydride. This increases the probability of neutrons escaping from the fuel, leading to a higher probability of neutron absorption outside the fuel rods. The ratio of neutron absorption in the fuel to lattice absorption decreases, resulting in decreased reactivity. This is the main reason for the large reactive transient negative temperature coefficient of the uranium-zirconium hydride reactor core, known as the lattice effect. Simultaneously, after neutrons gain energy, their energy spectrum hardens, increasing U-238 resonance absorption and core leakage. These factors also contribute to the transient negative temperature coefficient of metal hydride fuel reactors. Therefore, metal hydride fuels possess unique transient negative reactivity and inherent safety.

[0009] Uranium-zirconium alloy fuel has a high uranium density, resulting in better core breeding characteristics. Cores loaded with uranium-zirconium alloy fuel, on the other hand, have a softer energy spectrum and a lower critical mass due to the presence of hydrogen. Furthermore, since metal hydride fuel is a hydrogen-containing fuel produced through a hydrogen permeation process, it exhibits good compatibility with metallic fuels. Therefore, this application achieves customized core energy spectrum design by simultaneously arranging metal hydride fuel and metallic fuel in the core and adjusting their ratio according to the core's energy spectrum hardness requirements.

[0010] This application designs the metal hydride fuel rod fraction to be from 0% to 100%, adjusting the fraction according to the core energy spectrum requirements. A higher fraction of metal hydride fuel rods results in a softer core energy spectrum, and vice versa. When the metal hydride fuel rod fraction is reduced to 0%, the core exhibits a fast neutron spectrum, which can fully utilize the high uranium density characteristics of uranium-zirconium alloy fuel to achieve core nuclear fuel breeding. When the metal hydride fuel rod fraction is increased to 100%, the core exhibits a thermal neutron spectrum, which can effectively utilize the thermal spectral environment to achieve the maximum reduction in core criticality mass and improve uranium utilization.

[0011] In any fuel assembly of this application, the proportion of metal hydride fuel rods is preferably 10% to 99%; more preferably 20% to 98%; even more preferably 30% to 98%; even more preferably 50% to 95%; even more preferably 60% to 95%; and even more preferably 75% to 95%.

[0012] Preferably, the metal hydride fuel is selected from uranium zirconium hydride fuel (preferably UZrH). 1.6 (fuel) and yttrium uranium hydride fuel (preferably UYH) 1.85 At least one of the following: the metallic fuel is selected from uranium-zirconium alloy fuel (preferably U-10Zr alloy fuel).

[0013] UZrH 1.6 Fuel is used in reactor cores with higher moderation requirements, while UYH 1.85 The fuel is used in reactor cores with higher fuel temperatures; the present invention preferably uses U-10Zr alloy fuel because it has better compatibility with metal hydride fuels.

[0014] Preferably, the metal hydride fuel rods and the metal fuel rods are uniformly mixed in the fuel assembly. This ensures that the hydrogen atoms in the metal hydride fuel can adequately moderate the core neutrons, while simultaneously ensuring that the metal fuel is in a moderated energy spectrum environment.

[0015] Preferably, the fuel enrichment in the metal hydride fuel rod is 25%~38%, and the fuel enrichment in the metal fuel rod is 6%~12%. By using fuels with different enrichment levels in the two types of fuels, the equivalent nucleon density of uranium in the two fuels is made approximately equal, thereby flattening the core power distribution.

[0016] Preferably, a combustible poison is uniformly dispersed in the metal hydride fuel rods; the combustible poison is selected from at least one element or compound of erbium, gadolinium, hafnium, and europium. The addition of a combustible poison to the metal hydride fuel rods controls the residual reactivity of the reactor core.

[0017] Preferably, several of the fuel assemblies are arranged in a fuel enrichment zone from the core center region to the outer region; from the core center region outward along the radial direction, the fuel enrichment is successively low enrichment fuel assembly, medium enrichment fuel assembly and high enrichment fuel assembly; the core radial direction adopts a different fuel enrichment zone design to flatten the core power distribution.

[0018] Preferably, in the high-enrichment fuel assembly, the enrichment of metal hydride fuel is 35%~38%, preferably 35%~36%, and the enrichment of metal fuel is 10%~12%, preferably 10%~11%; in the medium-enrichment fuel assembly, the enrichment of metal hydride fuel is 30%~35%, preferably 30%~32%, and the enrichment of metal fuel is 8%~10%, preferably 8%~9%; in the low-enrichment fuel assembly, the enrichment of metal hydride fuel is 25%~30%, preferably 28%~30%, and the enrichment of metal fuel is 6%~9%, preferably 7%~8%.

[0019] More preferably, in the high-enrichment fuel assembly, the content of the combustible poison is 0.8% to 1%; in the medium-enrichment fuel assembly, the content of the combustible poison is 0.6% to 0.8%; and in the low-enrichment fuel assembly, the content of the combustible poison is 0.4% to 0.6%.

[0020] By adopting a zoning design based on the content of combustible poisons, combined with enrichment zoning, the core power distribution and burnup distribution are flattened.

[0021] The fuel assembly of the present invention includes a fuel assembly with a control rod and a fuel assembly without a control rod. The fuel assembly with a control rod includes a fuel assembly with a regulating rod, a fuel assembly with a safety rod, and a fuel assembly with a compensation rod.

[0022] Preferably, in the fuel assembly without control rods, the ratio of the number of metal hydride fuel rods to the number of metal fuel rods is 6~9:1; in the fuel assembly with control rods, the ratio of the number of metal hydride fuel rods to the number of metal fuel rods is 10~12:1.

[0023] Preferably, low-enrichment fuel assemblies without control rods are arranged in the central region of the core, low-enrichment fuel assemblies with conditioning rods are symmetrically arranged around the low-enrichment fuel assemblies without control rods, medium-enrichment fuel assemblies without control rods are arranged in the central region of the core, medium-enrichment fuel assemblies with compensation rods are symmetrically dispersed within the medium-enrichment fuel assemblies without control rods, high-enrichment fuel assemblies with safety rods are symmetrically arranged around the medium-enrichment fuel assemblies without control rods, and high-enrichment fuel assemblies without control rods are arranged on the outermost periphery of the core.

[0024] Preferably, the control rod-less fuel assembly of the present invention includes a metal hydride fuel rod, a metal fuel rod, an assembly box, and lead-bismuth; the regulating rod-containing fuel assembly of the present invention includes a metal hydride fuel rod, a metal fuel rod, a regulating rod, an assembly box, and lead-bismuth; the safety rod-containing fuel assembly of the present invention includes a metal hydride fuel rod, a metal fuel rod, a safety rod, an assembly box, and lead-bismuth; the compensation rod-containing fuel assembly of the present invention includes a metal hydride fuel rod, a metal fuel rod, a compensation rod, an assembly box, and lead-bismuth.

[0025] Preferably, in the fuel assembly containing a control rod (adjusting rod / compensation rod / safety rod) of the present invention, the control rod (adjusting rod / compensation rod / safety rod) is located at the center of the fuel assembly, and metal hydride fuel rods and metal fuel rods are uniformly arranged on the outer periphery of the control rod (adjusting rod / compensation rod / safety rod).

[0026] Preferably, the metal hydride fuel rod of the present invention comprises, from the inside out, a metal hydride fuel core, helium, a stainless steel cladding, and lead-bismuth; the metal fuel rod of the present invention comprises, from the inside out, a metal fuel core, helium, a stainless steel cladding, and lead-bismuth; the safety rod of the present invention comprises, from the inside out, a B4C core, helium, a stainless steel cladding, air, a control rod guide tube, and lead-bismuth; the compensation rod of the present invention comprises, from the inside out, a counterweight tungsten, helium, a stainless steel cladding, helium, a B4C core, helium, a stainless steel cladding, lead-bismuth, a control rod guide tube, and lead-bismuth; the regulating rod of the present invention comprises, from the inside out, a counterweight tungsten, helium, a stainless steel cladding, helium, a B4C core, helium, a stainless steel cladding, lead-bismuth, a control rod guide tube, and lead-bismuth.

[0027] Preferably, the safety rod of the present invention has a B4C B-10 content of 90%, the adjustment rod has a B4C B-10 content of 40%, and the compensation rod has a B4C B-10 content of 60%.

[0028] In one embodiment, the core power of the present invention is 500 MWt, and the lifespan is 1000 EFPD.

[0029] In a further preferred embodiment, the reactor core of the present invention comprises a total of 199 fuel assemblies, including 25 low-enrichment fuel assemblies without control rods, 6 low-enrichment fuel assemblies with conditioning rods, 60 medium-enrichment fuel assemblies without control rods, 18 medium-enrichment fuel assemblies with compensation rods, 12 high-enrichment fuel assemblies with safety rods, and 78 high-enrichment fuel assemblies without control rods; the equivalent diameter of the active region is 209 cm, the height of the active region is 120 cm, the core height-to-diameter ratio is 0.58, and the core power density is 122 W / cm². 3 The initial uranium loading at the end of the reactor core's lifespan is 7.74 tons, and the average burnup depth at the end of its lifespan is 65 GWd / tU. Further preferably, 25 low-enrichment fuel assemblies without control rods are arranged in the central region of the core, 6 low-enrichment fuel assemblies with conditioning rods are symmetrically arranged around the low-enrichment fuel assemblies without control rods, 60 medium-enrichment fuel assemblies without control rods are arranged in the central region of the core, 18 medium-enrichment fuel assemblies with compensation rods are symmetrically distributed 1 / 6 within the medium-enrichment fuel assemblies without control rods, 12 high-enrichment fuel assemblies with safety rods are symmetrically arranged 1 / 6 around the medium-enrichment fuel assemblies without control rods, and 78 high-enrichment fuel assemblies without control rods are arranged on the outermost periphery of the core. More preferably, the core control rods are divided into safety rod groups S1~S6, regulating rod groups P1~P6, and compensation rod groups B1~B6 according to their functions. Each safety rod group has 2 bundles, each regulating rod group has 1 bundle, and each compensation rod group has 3 bundles. Each group of control rods is controlled by a drive mechanism to lift or insert the control rod absorber into the core. Further preferred designs include a fuel rod core radius of 0.40 cm, a stainless steel cladding inner diameter of 0.41 cm, an outer diameter of 0.47 cm, a fuel rod center distance of 1.09 cm, and a grid pitch-to-diameter ratio of 1.16. Each fuel assembly contains 8 fuel rod coils, with the control rod occupying 4 coils. Fuel assemblies without control rods contain a total of 169 fuel rods, while those with control rods contain 132 fuel rods. The assembly box has an inner side-to-side distance of 13.70 cm, an outer side-to-side distance of 14.10 cm, an assembly center distance of 14.30 cm, and a control rod guide tube with an outer side-to-side distance of 6.19 cm and an inner radius of 2.63 cm. Further preferably, the fuel in the reactor core is UZrH 1.6 In a hybrid arrangement strategy with U-10Zr, UZrH is used in control rod-less fuel assemblies. 1.6 The fuel assembly contains 150 fuel rods, 19 of which are U-10Zr fuel. The UZrH... 1.6 The number of fuel rods is 120, and the number of U-10Zr fuel rods is 12; Further preferably, the reactor core is divided into radial zones based on fuel enrichment. High-enrichment fuel assemblies contain UZrH... 1.6The fuel enrichment is 35%, containing 0.9% Er by mass and 10% U-10Zr by mass; the medium-enriched fuel assembly contains UZrH 1.6 The fuel enrichment is 32%, containing 0.7% Er by mass, and 9% U-10Zr enrichment; the low-enrichment fuel assembly contains UZrH 1.6 The fuel enrichment is 29%, the Er content is 0.5% by mass, and the U-10Zr enrichment is 8%. Further optimized, the B4C B-10 content in the 12 safety rods is 90%, the B4C B-10 content in the 6 regulating rods is 40%, and the B4C B-10 content in the 18 compensating rods is 60%. The total value of the safety rods is 8566 pcm, the regulating rods are 5878 pcm, and the compensating rods are 19877 pcm. The core reactivity control rods meet the design requirements for shutdown depth and sticking rods. A further preferred embodiment is that the core lifting procedure involves fully lifting the safety rods, raising the regulating rods to half the core height, and raising the compensating rods to core criticality. During the burnup process, the compensating rods are raised to compensate for burnup reactivity losses, and the regulating rods do not need to compensate for the reactivity requirements of power rise and fall or for short-term reaction disturbance compensation.

[0030] The present invention has at least the following advantages and beneficial effects: (1) This invention utilizes the high uranium density and high multiplication characteristics of metal fuels and the hydrogen atom moderation characteristics of metal hydride fuels to mix and arrange metal fuels and metal hydride fuels. At the same time, the ratio of metal hydride fuels to metal fuels is adjusted according to the core power life and other design requirements, thereby realizing customized adjustment of the core energy spectrum and optimizing core performance to meet the needs of different application scenarios.

[0031] (2) In this invention, metal hydride fuel and metal fuel are uniformly mixed and arranged in any fuel assembly, so that the hydrogen atoms in the metal hydride fuel can fully slow down the core neutrons, while ensuring that the metal fuel is in a slowed energy spectrum environment.

[0032] (3) The metal hydride fuel of the present invention uses medium-high enrichment fuel and the metal fuel uses medium-low enrichment fuel. By using fuels with different enrichment in the two types of fuels, the equivalent nucleon density of uranium in the two fuels is approximately equal, so as to flatten the core power distribution.

[0033] (4) The metal hydride fuel of the present invention adopts a uniformly dispersed combustible poison design to control the residual reactivity of the reactor core.

[0034] (5) The reactor core of the present invention adopts a radial zoning design with different fuel enrichment to flatten the reactor core power distribution. At the same time, it adopts a zoning design with combustible toxic substance content, in conjunction with enrichment zoning, to flatten the reactor core power distribution and burnup distribution. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the metal hydride fuel rod in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the structure of the metal fuel rod in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the structure of the safety bar in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the structure of the adjusting rod and the compensating rod in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the structure of the control rod-less fuel assembly in Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of the structure of the fuel assembly containing the safety rod in Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of the structure of the fuel assembly with regulating rod in Embodiment 1 of the present invention; Figure 8 This is a schematic diagram of the fuel assembly with compensation rods in Embodiment 1 of the present invention; Figure 9 This is a schematic diagram of the 500MWt reactor core arrangement structure in Embodiment 1 of the present invention.

[0036] Figure label: 1-Metal hydride fuel core, 2-Helium, 3-Stainless steel cladding, 4-Lead bismuth, 5-B4C core, 6-Air, 7-Control rod guide tube, 8-Counterweight tungsten, 9-Metal fuel core, 51-Metal hydride fuel rod, 52-Component box, 53-Compensation rod, 54-Metal fuel rod, 55-Safety rod, 56-Regulating rod, 101-Low enrichment fuel assembly without control rod, 102-Low enrichment fuel assembly with regulating rod, 103-Medium enrichment fuel assembly without control rod, 104-Medium enrichment fuel assembly with compensation rod, 105-High enrichment fuel assembly with safety rod, 106-High enrichment fuel assembly without control rod. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the present invention will be further described below in conjunction with specific embodiments. All features disclosed in this specification, except for mutually exclusive features and / or steps, can be combined in any way.

[0038] The following embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way.

[0039] Example 1 As attached Figure 1 - Appendix Figure 9 As shown, this embodiment provides a reactor core with a mixed arrangement of metal hydride fuel and metal fuel, a core power of 500 MWt, and a lifespan of 1000 EFPD.

[0040] The reactor core contains 199 fuel assemblies: 25 low-enrichment fuel assemblies without control rods (101), 6 low-enrichment fuel assemblies with conditioning rods (102), 60 medium-enrichment fuel assemblies without control rods (103), 18 medium-enrichment fuel assemblies with compensating rods (104), 12 high-enrichment fuel assemblies with safety rods (105), and 78 high-enrichment fuel assemblies without control rods (106). The equivalent diameter of the active zone is 209 cm, the height of the active zone is 120 cm, the core height-to-diameter ratio is 0.58, and the core power density is 122 W / cm³. 3 The initial uranium loading at the end of the reactor core's lifespan is 7.74 tons, and the average burnup depth at the end of its lifespan is 65 GWd / tU.

[0041] Specifically, the fuel assembly in this embodiment includes fuels using UZrH 1.6 Metal hydride fuel rod 51 using U-10Zr as fuel; as attached Figure 1 As shown, the metal hydride fuel rod 51 consists of, from the inside out, a metal hydride fuel core 1 (in this embodiment, UZrH). 1.6 Fuel core), helium 2, stainless steel cladding 3, and lead-bismuth 4; as attached Figure 2 As shown, the metal fuel rod 54 in this embodiment includes a metal fuel core 9 (U-10Zr fuel core in this embodiment), helium 2, stainless steel cladding 3, and lead-bismuth 4, arranged sequentially from the inside out.

[0042] Specifically, the structure of the safety rod 55 in this embodiment is shown in the attached figure. Figure 3 As shown, the structure includes, from the inside out, a B4C core 5, helium gas 2, a stainless steel cladding 3, air 6, a control rod guide tube 7, and lead-bismuth 4; the structures of the adjusting rod 56 and the compensating rod 53 in this embodiment are as shown in the attached figure. Figure 4 As shown, the structure includes, from the inside out, a counterweight tungsten 8, helium 2, a stainless steel cladding 3, helium 2, a B4C core 5, helium 2, a stainless steel cladding 3, lead-bismuth 4, a control rod guide tube 7, and lead-bismuth 4. The difference between the adjusting rod 56 and the compensating rod 53 is that the B4C content in the B4C core 5 is different.

[0043] A schematic diagram of the control rodless fuel assembly of this embodiment is attached. Figure 5As shown, in the control rod-less fuel assembly, metal hydride fuel rods 51 and metal fuel rods 54 are uniformly mixed and assembled in the assembly box 52, and loaded in a lead-bismuth 4 alloy; the structural schematic diagram of the fuel assembly with safety rods in this embodiment is shown below. Figure 6 As shown, in the fuel assembly with safety rods, safety rod 55 is arranged at the center of the fuel assembly, while metal hydride fuel rods 51 and metal fuel rods 54 are evenly arranged on the outer periphery and finally mixed and assembled in the assembly box 52, loaded in a lead-bismuth 4 alloy; a schematic diagram of the fuel assembly with regulating rods in this embodiment is shown below. Figure 7 As shown, a schematic diagram of the fuel assembly containing the compensation rod is as follows: Figure 8 As shown, both have the same structure. The regulating rod 56 or the compensating rod 53 is arranged in the center of the fuel assembly, and the metal hydride fuel rod 51 and the metal fuel rod 54 are evenly arranged on the outer periphery. They are finally mixed and assembled in the assembly box 52 and loaded in the lead-bismuth 4 alloy.

[0044] As attached Figure 9 As shown, in this embodiment, 25 low-enrichment fuel assemblies without control rods 101 are arranged in the central region of the core, 6 low-enrichment fuel assemblies with conditioning rods 102 are symmetrically arranged around the low-enrichment fuel assemblies without control rods 101, 60 medium-enrichment fuel assemblies without control rods 103 are arranged in the central region of the core, 18 medium-enrichment fuel assemblies with compensation rods 104 1 / 6 are symmetrically dispersed within the medium-enrichment fuel assemblies without control rods 103, 12 high-enrichment fuel assemblies with safety rods 105 1 / 6 are symmetrically arranged around the medium-enrichment fuel assemblies without control rods 103, and 78 high-enrichment fuel assemblies without control rods 106 are arranged on the outermost periphery of the core.

[0045] In this embodiment, all fuel assemblies are arranged with a mixture of metal hydride fuel rods 51 and metal fuel rods 54. Specifically, in the control rod-less fuel assembly, the metal hydride fuel rod 51 (UZrH) 1.6 The number of fuel rods is 150, and the number of metal fuel rods 54 (U-10Zr fuel rods) is 19. In the fuel assembly containing control rods, the number of metal hydride fuel rods 51 (UZrH) is... 1.6 The number of fuel rods is 120, and the number of metal fuel rods 54 (U-10Zr fuel rods) is 12.

[0046] The reactor core is divided radially by fuel enrichment zones. High-enrichment fuel assemblies contain metal hydride fuel rods 51 (UZrH). 1.6 The fuel enrichment of the fuel rod is 35%, and the Er content is 0.9% by mass. The fuel enrichment of the metal fuel rod 54 (U-10Zr fuel rod) is 10%. The medium enrichment fuel assembly includes metal hydride fuel rod 51 (UZrH). 1.6The fuel enrichment of the fuel rod is 32%, and the Er content is 0.7% by mass. The fuel enrichment of the metal fuel rod 54 (U-10Zr fuel rod) is 9%. The low enrichment fuel assembly contains metal hydride fuel rod 51 (UZrH). 1.6 The fuel enrichment of the fuel rod is 29%, and the mass percentage of Er is 0.5%. The fuel enrichment of the metal fuel rod 54 (U-10Zr fuel rod) is 8%.

[0047] In this embodiment, the metal hydride fuel rod 51 and the metal fuel rod 54 have the same dimensions, specifically: a fuel rod core radius of 0.40 cm, an inner diameter of 0.41 cm and an outer diameter of 0.47 cm for the stainless steel cladding 3, a fuel rod center distance of 1.09 cm, and a grid pitch-to-diameter ratio of 1.16. Each fuel assembly contains 8 fuel rod coils, with the control rod occupying 4 coils. Fuel assemblies without control rods contain 169 fuel rods, while fuel assemblies with control rods contain 132 fuel rods. The assembly box 52 has an inner side-to-side distance of 13.70 cm, an outer side-to-side distance of 14.10 cm, an assembly center distance of 14.30 cm, and a control rod guide tube 7 with an outer side-to-side distance of 6.19 cm and an inner radius of 2.63 cm.

[0048] Specifically, in this embodiment, the core control rods are divided into safety rod groups S1~S6, regulating rod groups P1~P6, and compensation rod groups B1~B6 according to their functions. Each safety rod group has 2 bundles, each regulating rod group has 1 bundle, and each compensation rod group has 3 bundles. Each group of control rods is controlled by a drive mechanism to lift or insert the control rod absorber into the core.

[0049] The 12 safety rods (55) contain 90% B4C B-10, the 6 regulating rods (56) contain 40% B4C B-10, and the 18 compensating rods (53) contain 60% B4C B-10. The total value of the safety rods (55) is 8566 pcm, the regulating rods (56) are 5878 pcm, and the compensating rods (53) are 19877 pcm. The core reactivity control rods meet the design requirements for shutdown depth and sticking rods.

[0050] During operation, the core lifting procedure in this embodiment is as follows: safety rod 55 is fully lifted, regulating rod 56 is raised to half the core height, and compensation rod 53 is raised to the core criticality. During the burnup process, compensation rod 53 is raised to compensate for burnup reactivity loss. Regulating rod 56 does not need to compensate for the reactivity requirements of power rise and fall or for short-term reaction disturbance compensation.

[0051] In summary, the reactor core of this embodiment is a hybrid arrangement of metal hydride fuel and metal fuel. This arrangement can utilize the high uranium density and high multiplication characteristics of metal fuel, as well as the hydrogen atom moderation characteristics of metal hydride fuel. At the same time, the ratio of metal hydride to metal fuel can be adjusted according to the core power lifetime and other design requirements, thereby achieving customized adjustment of the core energy spectrum and optimizing core performance.

[0052] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

Claims

1. A reactor core with a mixture of metal hydride fuel and metal fuel, characterized in that, It includes several fuel assemblies; each of the fuel assemblies includes a metal hydride fuel rod loaded with metal hydride fuel and a metal fuel rod loaded with metal fuel; in any of the fuel assemblies, the proportion of the metal hydride fuel rod is 0 to 100%.

2. The reactor core with a mixture of metal hydride fuel and metal fuel as described in claim 1, characterized in that, The metal hydride fuel is selected from at least one of uranium zirconium hydride fuel and uranium yttrium hydride fuel; the metal fuel is selected from uranium zirconium alloy fuel.

3. The reactor core with a mixture of metal hydride fuel and metal fuel according to claim 1, characterized in that, The metal hydride fuel rod and the metal fuel rod are uniformly mixed in the fuel assembly.

4. The reactor core with a mixture of metal hydride fuel and metal fuel according to claim 1, characterized in that, The fuel enrichment in the metal hydride fuel rod is 25%~38%, and the fuel enrichment in the metal fuel rod is 6%~12%.

5. The reactor core with a mixture of metal hydride fuel and metal fuel according to claim 1, characterized in that, The metal hydride fuel rod contains a flammable poison that is uniformly dispersed within it; the flammable poison is selected from at least one element or compound of erbium, gadolinium, hafnium, and europium.

6. The reactor core with a mixture of metal hydride fuel and metal fuel according to claim 5, characterized in that, Several of the fuel assemblies are arranged in fuel enrichment zones from the core center region to the outer region; from the core center region outward along the radial direction, low enrichment fuel assemblies, medium enrichment fuel assemblies and high enrichment fuel assemblies are arranged sequentially. In the high-enrichment fuel assembly, the fuel enrichment of metal hydride fuel is 35%~38%, and the fuel enrichment of metal fuel is 10%~12%; in the medium-enrichment fuel assembly, the fuel enrichment of metal hydride fuel is 30%~35%, and the fuel enrichment of metal fuel is 8%~10%; in the low-enrichment fuel assembly, the fuel enrichment of metal hydride fuel is 25%~30%, and the fuel enrichment of metal fuel is 6%~9%.

7. The reactor core with a mixture of metal hydride fuel and metal fuel as described in claim 6, characterized in that, In the high-enrichment fuel assembly, the content of the combustible poison is 0.8% to 1%; in the medium-enrichment fuel assembly, the content of the combustible poison is 0.6% to 0.8%; and in the low-enrichment fuel assembly, the content of the combustible poison is 0.4% to 0.6%.

8. The reactor core with a mixture of metal hydride fuel and metal fuel according to any one of claims 1 to 7, characterized in that, The fuel assembly includes a fuel assembly with a control rod and a fuel assembly without a control rod. The fuel assembly with a control rod includes a fuel assembly with a regulating rod, a fuel assembly with a safety rod, and a fuel assembly with a compensation rod.

9. The reactor core with a mixture of metal hydride fuel and metal fuel according to claim 8, characterized in that, In the fuel assembly without control rods, the ratio of the number of metal hydride fuel rods to the number of metal fuel rods satisfies: 6~9:1; in the fuel assembly with control rods, the ratio of the number of metal hydride fuel rods to the number of metal fuel rods satisfies: 10~12:

1.

10. The reactor core with a mixture of metal hydride fuel and metal fuel according to claim 8, characterized in that, Low-enrichment fuel assemblies without control rods are arranged in the central region of the core; low-enrichment fuel assemblies with conditioning rods are symmetrically arranged around the low-enrichment fuel assemblies without control rods; medium-enrichment fuel assemblies without control rods are arranged in the central region of the core; medium-enrichment fuel assemblies with compensation rods are symmetrically dispersed within the medium-enrichment fuel assemblies without control rods; high-enrichment fuel assemblies with safety rods are symmetrically arranged around the medium-enrichment fuel assemblies without control rods; and high-enrichment fuel assemblies without control rods are arranged on the outermost periphery of the core.

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