A lead bismuth cooled reactor core employing a self-moderating fuel

Abstract

The application discloses a lead-bismuth cooled reactor core adopting spontaneous moderation fuel, which comprises a plurality of fuel assemblies, a plurality of control rod assemblies and a calandria, the control rod assemblies are arranged in the fuel assemblies at intervals, and the reactor core is arranged in coolant surrounded by the calandria; the reactor core adopts hexagonal fuel assemblies, a plurality of fuel rods arranged in the fuel assemblies are arranged in an equilateral triangle, and solid moderation rods are arranged at six corners of the fuel assemblies; a core body in the fuel rods adopts spontaneous moderation fuel, and a core body in the solid moderation rods adopts solid moderation material. On the basis of meeting the power demand of the reactor core, the design life and the shutdown safety design criterion, the application can better moderate neutrons in the reactor core, improves the reactor core reactivity, reduces the uranium loading and the size of the reactor core, reduces the shielding demand, and enhances the negative feedback safety of the reactor core.

Description

Technical Field

[0001] This invention relates to the field of nuclear reactor core technology, and more specifically to a lead-bismuth cooled reactor core using self-moderated fuel. Background Technology

[0002] Lead-cooled fast reactors (LFRs) are one of the "fourth generation" advanced fast reactor nuclear energy systems. Using lead or lead-bismuth alloys as coolants, they possess excellent neutron physics, thermal-hydraulic, and system safety properties, offering advantages such as high resource utilization, good safety, and good economic efficiency. They align with the national development roadmap of "thermal reactor—fast reactor—fusion reactor" for nuclear energy technology and serve as an excellent platform for the leapfrog innovation and development of nuclear power technology in my country.

[0003] However, existing lead-cooled fast reactor cores, while meeting the core reactivity requirements, have insufficient uranium loading and core size, which cannot adequately shield the reactor core and result in inadequate negative feedback security. Summary of the Invention

[0004] The purpose of this invention is to provide a lead-bismuth cooled reactor core using self-moderated fuel. While meeting the core power requirements, design life, and shutdown safety design criteria, this invention can better moderate the neutrons in the core, improve core reactivity, reduce uranium loading and core size, reduce shielding requirements, and enhance the negative feedback safety of the core.

[0005] This invention is achieved through the following technical solution:

[0006] A lead-bismuth cooled reactor core using spontaneously moderated fuel, the core comprising a plurality of fuel assemblies, a plurality of control rod assemblies and a shroud, the control rod assemblies being spaced apart in the fuel assemblies, and the core being disposed in a coolant surrounded by the shroud;

[0007] The reactor core uses a hexagonal fuel assembly, and multiple fuel rods inside the fuel assembly are arranged in an equilateral triangle. Solid moderators are provided at the six corners of the fuel assembly.

[0008] The core of the fuel rod uses self-moderating fuel, and the core of the solid moderator rod uses solid moderator material.

[0009] This invention takes into account the characteristics of uranium zirconium hydride fuel, such as high-temperature stability, high hydrogen density, low neutron absorption cross section, excellent thermal conductivity, and good compatibility with stainless steel, which enable it to moderate the core energy spectrum. Therefore, this invention utilizes the spontaneous moderation characteristics of uranium zirconium hydride fuel and combines it with a solid zirconium hydride moderator to design a fuel-driven, spontaneously moderated lead-bismuth cooled reactor core with a long lifespan and enhanced safety. Compared with lead-bismuth fast reactors, this invention, while meeting core power requirements, design lifespan, and shutdown safety design criteria, can better moderate neutrons within the core, improve core reactivity, reduce uranium loading and core size, lower shielding requirements, and enhance the core's negative feedback safety.

[0010] As a further preferred option, the core of the fuel rod is made of zirconium uranium hydride fuel.

[0011] As a further preferred embodiment, the core of the solid moderator rod is made of zirconium hydride.

[0012] As a further preferred embodiment, the reactor core is loaded with a total of 96 fuel assemblies and 31 control rod assemblies;

[0013] Each fuel assembly box contains 55 zirconium hydride fuel rods and 6 zirconium hydride solid moderator rods;

[0014] Each control rod assembly includes 36 zirconium hydride fuel rods, 19 B4C control rods, and 6 zirconium hydride moderator rods.

[0015] The fuel rod core uses uranium zirconium hydride with a U-235 enrichment of 30.6% as fuel, and the ratio of hydrogen to metal elements in the fuel is 1.6.

[0016] As a further preferred embodiment, the fuel rods within the fuel assembly are fixed together using a wire-wound structure.

[0017] As a further preferred embodiment, the control rod assemblies are spaced apart within a portion of the fuel assembly.

[0018] As a further preferred embodiment, both the fuel assembly and the control rod assembly are hexagonal in shape.

[0019] As a further preferred embodiment, the neutrons in the reactor core are slowed down to a lower energy spectrum, which is lower than the energy spectrum of a conventional lead-cooled fast reactor.

[0020] As a further preferred embodiment, the lower energy spectrum includes, but is not limited to, thermal spectrum, hyperthermal spectrum, and mixed spectrum.

[0021] This invention, by slowing down the neutron energy spectrum within the reactor core to the hyperthermal energy spectrum, effectively improves core reactivity, reduces the uranium loading and core size, while simultaneously lowering shielding requirements and enhancing the core's negative feedback security. The core structure and parameters can be adjusted and modified within design limits to meet core power requirements, design lifespan, and critical safety requirements.

[0022] As a further preferred option, the coolant is a lead-bismuth alloy.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] This invention discloses a lead-bismuth cooled reactor core using self-moderated fuel. Utilizing the self-moderation characteristics of uranium zirconium hydride fuel, and combining it with a solid zirconium hydride moderator, this invention designs a fuel-driven, self-moderated lead-bismuth cooled reactor core with a long lifespan and enhanced safety. Compared to lead-bismuth fast reactors, this invention, while meeting core power requirements, design lifespan, and shutdown safety design criteria, can better moderate neutrons within the core, improving core reactivity, reducing uranium loading and core size, lowering shielding requirements, and enhancing the core's negative feedback safety. Attached Figure Description

[0025] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0026] Figure 1 This is a simplified radial diagram and a control rod grouping diagram of a lead-bismuth cooled reactor core using self-moderated fuel according to the present invention.

[0027] Figure 2 This is a simplified axial view of a lead-bismuth cooled reactor core using self-moderated fuel according to the present invention.

[0028] Figure 3 This is a schematic diagram illustrating the change in the effective multiplication factor as burnup of a lead-bismuth cooled reactor core using self-moderated fuel according to the present invention.

[0029] Figure reference numerals and corresponding component names:

[0030] 10-Fuel assembly, 11-Control rod assembly, 12-Enclosure, 13-Coolant, 14-Solid moderator rod. Detailed Implementation

[0031] In the following, the terms “comprising” or “may include” as used in various embodiments of the invention indicate the presence of an inventive function, operation, or element, and do not limit the addition of one or more functions, operations, or elements. Furthermore, as used in various embodiments of the invention, the terms “comprising,” “having,” and their cognates are intended only to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing, or adding one or more combinations of the foregoing.

[0032] In various embodiments of the invention, the expression "or" or "at least one of A and / or B" includes any combination or all combinations of the words listed simultaneously. For example, the expression "A or B" or "at least one of A and / or B" may include A, may include B, or may include both A and B.

[0033] The expressions used in the various embodiments of the present invention (such as "first," "second," etc.) may modify various constituent elements in the various embodiments, but do not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only used for the purpose of distinguishing one element from other elements. For example, a first user device and a second user device refer to different user devices, although both are user devices. For example, a first element may be referred to as a second element without departing from the scope of the various embodiments of the present invention, and similarly, a second element may also be referred to as a first element.

[0034] It should be noted that if a description is made of "connecting" one component to another, then the first component can be directly connected to the second component, and a third component can be "connected" between the first and second components. Conversely, when a component is "directly connected" to another component, it can be understood that there is no third component between the first and second components.

[0035] The terminology used in the various embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the various embodiments of the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the invention pertain. The terms (such as those defined in a generally used dictionary) are to be interpreted as having the same meaning as in the context of the relevant technical field and are not to be interpreted as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of the invention.

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0037] Example 1

[0038] like Figure 1 As shown, the present invention discloses a lead-bismuth cooled reactor core using self-moderated fuel. The core includes a plurality of fuel assemblies 10, a plurality of control rod assemblies 11, and a containment 12. The control rod assemblies 11 are arranged at intervals in the fuel assemblies 10, and the core is arranged in a lead-bismuth alloy coolant 13 surrounded by the containment 12.

[0039] The reactor core adopts a hexagonal fuel assembly 10, and multiple fuel rods arranged in an equilateral triangle are provided inside the fuel assembly 10. The fuel rods are fixed together by a wire winding structure. Solid moderators 14 are provided at the six corners of the fuel assembly 10.

[0040] The core of the fuel rod uses spontaneously moderating fuel, represented by zirconium hydride, and the core of the solid moderator rod 14 uses solid moderator material, represented by zirconium hydride.

[0041] As a further implementation, the control rod assembly 11 is spaced apart in a portion of the fuel assembly 10.

[0042] As a further implementation, both the fuel assembly 10 and the control rod assembly 11 are hexagonal in shape, such as a regular hexagon.

[0043] As a further implementation, the neutrons in the reactor core are slowed down to a lower energy spectrum, which is lower than the energy spectrum of a conventional lead-cooled fast reactor. The lower energy spectrum includes, but is not limited to, thermal, hyperthermal, and mixed spectra.

[0044] This invention, by slowing down the neutron energy spectrum within the reactor core to the hyperthermal energy spectrum, effectively improves core reactivity, reduces the uranium loading and core size, while simultaneously lowering shielding requirements and enhancing the core's negative feedback security. The core structure and parameters can be adjusted and modified within design limits to meet core power requirements, design lifespan, and critical safety requirements.

[0045] The working principle is as follows: Existing lead-cooled fast reactor cores, while meeting core reactivity requirements, suffer from insufficient uranium loading and core size, resulting in inadequate shielding and insufficient negative feedback safety. This invention considers the characteristics of zirconium hydride fuel, including high-temperature stability, high hydrogen density, low neutron absorption cross-section, excellent thermal conductivity, and good compatibility with stainless steel, which can moderate the core energy spectrum. Therefore, this invention utilizes the spontaneous moderation characteristics of zirconium hydride fuel, combined with a solid zirconium hydride moderator, to design a fuel-driven, self-moderated lead-bismuth-cooled reactor core with a long lifespan and higher safety. Compared to lead-bismuth fast reactors, this invention, while meeting core power requirements, design lifespan, and shutdown safety design criteria, can better moderate neutrons within the core, improving core reactivity, reducing uranium loading and core size, lowering shielding requirements, and enhancing negative feedback safety.

[0046] Example 2

[0047] like Figures 1 to 3 As shown, the difference between this embodiment and Embodiment 1 is that this embodiment provides a core design scheme for a 20MW uranium zirconium hydride hyperthermic lead-bismuth cooled reactor, and the specific implementation is as follows:

[0048] like Figure 1 As shown, Figure 1 This is a simplified radial diagram and control rod grouping diagram of a lead-bismuth cooled reactor core using self-moderated fuel according to the present invention. The entire reactor is loaded with 96 hexagonal fuel assemblies 10 and 31 control rod assemblies 11, which are divided into 5 groups. The entire core is located within a lead-bismuth alloy coolant enclosed in a shroud. The equivalent diameter of the active zone of the core is 1317.1 mm, the shroud thickness is 20 mm, and the outer diameter of the shroud is 1600 mm. Figure 1 The control rod assembly 11 includes rod group 1, rod group 2, rod group 3, rod group 4 and rod group 5; the outermost arrangement is rod group 1; the middle arrangement is rod group 2 and rod group 3, which are arranged at intervals; the innermost arrangement is rod group 4 and rod group 5, which are arranged at intervals.

[0049] The 20MW uranium-zirconium hydride thermal spectrum lead-bismuth cooled reactor core comprises fuel assemblies 10, control rod assemblies 11, and a cladding 12. The control rod assemblies 11 are spaced apart within the fuel assemblies 10, and the entire core is enclosed in lead-bismuth alloy coolant 13 within the cladding 12. The core contains 96 fuel assemblies 10 and 31 control rod assemblies 11. Each fuel assembly 10 contains 55 uranium-zirconium hydride fuel rods and 6 zirconium hydride moderator rods. Each control rod assembly 11 contains 36 uranium-zirconium hydride fuel rods, 19 B4C control rods, and 6 zirconium hydride moderator rods. The moderator rods are distributed at the six corners of each hexagonal assembly. The fuel rods use uranium-zirconium hydride with a U-235 enrichment of 30.6% as fuel, and the hydrogen to metal ratio in the fuel is 1.6. The fuel pellet diameter is 10.4 mm, and the cladding thickness is 0.7 mm. The moderator rods use ZrH2O. 1.6 As a solid moderator, the zirconium hydride core has a diameter of 8 mm and a cladding thickness of 2 mm. The control rod absorber material is B4C, with a B-10 enrichment of 78.4%. The B4C core has a diameter of 10.4 mm and a cladding thickness of 0.7 mm. The control rods are arranged in five groups at intervals within the core. The equivalent diameter of the active region in the core is 1317.1 mm, the thickness of the ballast 12 is 20 mm, and the outer diameter of the ballast 12 is 1600 mm.

[0050] like Figure 2 As shown, Figure 2 This is a simplified axial view of the core of a lead-bismuth cooled reactor using self-moderated fuel according to the present invention. The active zone height of the core of the 20MW uranium zirconium hydride thermal spectrum lead-bismuth cooled reactor is 600mm, and the total core height is 900mm.

[0051] like Figure 3 As shown, Figure 3 This is a schematic diagram illustrating the change of the effective multiplication factor (Keff) of a lead-bismuth cooled reactor core using self-moderated fuel as a function of burnup. The initial loading effective multiplication factor (Keff) of the 20MW uranium zirconium hydride thermal spectrum lead-bismuth cooled reactor core was 1.206773. After 1500 days of full-power operation, Keff was 1.005986, achieving the design life requirement of 1500 EFPD.

[0052] When the reactor is cold-shutdown with one cluster of control rods, the core Keff values ​​are 0.981215 (rod group 1), 0.985157 (rod group 2), 0.983140 (rod group 3), 0.983045 (rod group 4) and 0.982745 (rod group 5), respectively, and the subcritical depth is greater than 1000 pcm, which meets the critical safety requirements for cold shutdown with one cluster of control rods.

[0053] Based on power requirements and design life, design adjustments can be made between 1MW and 200MW and between 3 and 10 years to determine the specific core structure and core parameters, ultimately meeting the requirements of power requirements, design life, and shutdown safety design criteria.

[0054] This invention takes into account the characteristics of uranium zirconium hydride fuel, such as high-temperature stability, high hydrogen density, low neutron absorption cross section, excellent thermal conductivity, and good compatibility with stainless steel, which enable it to moderate the core energy spectrum. Utilizing the spontaneous moderation properties of uranium zirconium hydride fuel, this invention, combined with a solid zirconium hydride moderator, designs a fuel-driven, spontaneously moderated lead-bismuth cooled reactor core with a long lifespan and enhanced safety. Compared to lead-bismuth fast reactors, this invention, while meeting core power requirements, design lifespan, and shutdown safety design criteria, can better moderate neutrons within the core, improve core reactivity, reduce uranium loading and core size, lower shielding requirements, and enhance the core's negative feedback safety.

[0055] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. 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 lead-bismuth cooled reactor core using self-generated moderated fuel, characterized in that, The reactor core includes several fuel assemblies (10), several control rod assemblies (11) and a bulge (12), the control rod assemblies (11) being spaced apart in the fuel assemblies (10), and the reactor core being arranged in a coolant (13) surrounded by the bulge (12); The reactor core adopts a hexagonal fuel assembly, and multiple fuel rods are arranged in an equilateral triangle inside the fuel assembly (10). Solid moderator rods (14) are provided at the six corners of the fuel assembly (10). The core of the fuel rod is made of self-moderating fuel, and the core of the solid moderator rod (14) is made of solid moderator material. The reactor core contains a total of 96 fuel assemblies (10) and 31 control rod assemblies (11); Each fuel assembly (10) includes 55 zirconium hydride fuel rods and 6 zirconium hydride solid moderator rods; Each control rod assembly (11) includes 36 zirconium hydride fuel rods, 19 B4C control rods and 6 zirconium hydride moderator rods. The fuel rod core uses uranium zirconium hydride with a U-235 enrichment of 30.6% as fuel, and the ratio of hydrogen to metal elements in the fuel is 1.

6.

2. The lead-bismuth cooled reactor core using self-generated moderated fuel according to claim 1, characterized in that, The core of the fuel rod uses zirconium hydride fuel.

3. A lead-bismuth cooled reactor core using self-generated moderated fuel according to claim 2, characterized in that, The core of the solid moderator rod (14) is made of zirconium hydride.

4. A lead-bismuth cooled reactor core using self-generated moderated fuel according to claim 1, characterized in that, The fuel rods in the fuel assembly (10) are fixed together by a wire winding structure.

5. A lead-bismuth cooled reactor core using self-generated moderated fuel according to claim 1, characterized in that, The control rod assembly (11) is spaced apart in a portion of the fuel assembly (10).

6. A lead-bismuth cooled reactor core using self-generated moderated fuel according to claim 1, characterized in that, Both the fuel assembly (10) and the control rod assembly (11) are hexagonal in shape.

7. A lead-bismuth cooled reactor core using self-generated moderated fuel according to claim 1, characterized in that, The neutrons in the reactor core are slowed down to a lower energy spectrum, which is lower than the energy spectrum of a conventional lead-cooled fast reactor.

8. A lead-bismuth cooled reactor core using self-generated moderated fuel according to claim 7, characterized in that, The lower energy spectrum includes thermal spectrum, hyperthermal spectrum, and mixed spectrum.

9. A lead-bismuth cooled reactor core using self-generated moderated fuel according to claim 1, characterized in that, The coolant (13) is a lead-bismuth alloy.

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