阅读说明：本技术 一种颗粒燃料芯体、燃料棒及金属冷却小型反应堆 (Pellet fuel core, fuel rod and small-size reactor of metal cooling ) 是由 夏榜样 孙伟 严明宇 余红星 柴晓明 李松蔚 李文杰 于 2019-11-21 设计创作，主要内容包括：本发明公开了一种颗粒燃料芯体、燃料棒及金属冷却小型反应堆,所述颗粒燃料芯体包括若干颗粒燃料,若干颗粒燃料均匀弥散到氧化铍基体中,形成高热导率的燃料芯体,所述颗粒燃料由燃料微球和包覆层构成,所述包覆层包覆在燃料微球外侧,所述包覆层采用耐高温、高热导率的碳化硅制成,所述燃料微球在燃料芯体中的体积份额为30％～60％；所述燃料微球释放的裂变气体通过包覆层、氧化铍基体进行包容,所述燃料微球二氧化铀或铀钚混合氧化物。本发明显著增大了燃料芯体的热导率以及燃料芯体与燃料棒外表面之间的导热系数,可以大幅降低燃料芯体温度,提高金属冷却小型反应堆的设计性能及运行安全性。(The invention discloses a particle fuel core, a fuel rod and a metal cooling small reactor, wherein the particle fuel core comprises a plurality of particle fuels, the particle fuels are uniformly dispersed into a beryllium oxide matrix to form a fuel core with high heat conductivity, the particle fuels comprise fuel microspheres and a coating layer, the coating layer is coated on the outer side of the fuel microspheres, the coating layer is made of high-temperature-resistant and high-heat-conductivity silicon carbide, and the volume fraction of the fuel microspheres in the fuel core is 30-60%; fission gas released by the fuel microspheres is contained through a coating layer and a beryllium oxide substrate, and the fuel microspheres are uranium dioxide or uranium plutonium mixed oxide. The invention obviously increases the heat conductivity of the fuel core and the heat conductivity coefficient between the fuel core and the outer surface of the fuel rod, can greatly reduce the temperature of the fuel core, and improves the design performance and the operation safety of the metal cooling small reactor.)

1. A particle fuel core is characterized by comprising a plurality of particle fuels (1), wherein the particle fuels (1) are uniformly dispersed in a beryllium oxide matrix (2) to form a fuel core with high heat conductivity, the particle fuels (1) are composed of fuel microspheres (5) and a coating layer (6), the coating layer (6) is coated outside the fuel microspheres (5), the coating layer (6) is made of high-temperature-resistant and high-heat-conductivity silicon carbide, and the volume fraction of the fuel microspheres (5) in the fuel core is 30-60%; fission gas released by the fuel microspheres (5) is contained through the coating layer (6) and the beryllium oxide substrate (2), and the fuel microspheres (5) are uranium dioxide or uranium plutonium mixed oxide.

2. A particulate fuel core according to claim 1, wherein the diameter of the particulate fuel (1) is 1.0mm and the thickness of the coating (6) is 0.2 mm.

3. A fuel rod comprising a particle fuel core as claimed in claim 1 or 2, characterized in that the fuel rod (7) comprises a cladding tube (3), the fuel core being arranged inside the cladding tube (3) and in close contact with the cladding tube (3), and the cladding tube (3) being provided with end plugs (4) at both ends.

4. A metal cooled miniature reactor, characterized in that the core of the reactor comprises 103 fuel assemblies (11) and 18 control rod assemblies (12), the fuel assemblies (11) and control rod assemblies (12) are uniformly staggered inside the core, and the fuel assemblies (11) and control rod assemblies (12) each comprise a fuel rod (7).

5. The metal cooled mini reactor as claimed in claim 4, wherein the fuel rods (7) have an outer diameter of 5.0mm to 7.0 mm.

6. The metal-cooled mini reactor according to claim 4, wherein the fuel assembly (11) comprises a plurality of fuel rods (7), an assembly cell (8), and a plurality of fuel rods (7) are arranged in the assembly cell (8) according to a regular triangular lattice.

7. The metal-cooled miniature reactor according to claim 4, wherein said control rod assembly (12) comprises a plurality of fuel rods (7), a guide tube (9) and an assembly box (8), wherein the guide tube (9) is located at the center point of the control rod assembly (12), the fuel rods (7) are uniformly arranged in the assembly box (8) around the guide tube (9) according to a regular triangular lattice, and the control rods (10) are arranged in the guide tube (9).

Technical Field

The invention relates to the technical field of nuclear reactors, in particular to a granular fuel core, a fuel rod and a metal cooling small reactor.

Background

The liquid metal coolant reactor is a main reactor type of an IV-th generation advanced nuclear energy system, such as a sodium-cooled fast reactor (SFR), a lead-cooled fast reactor (LFR) and the like, has good development potential in the aspects of nuclear fuel transmutation and proliferation, and also has the advantages of unique high power density and long service life. Therefore, various small metal-cooled reactor concept schemes are developed in various countries of the world aiming at different purposes and application scenes, such as Russian small lead bismuth cooled SVBR-75/100, American small natural circulation SSTAR pure lead cooled fast reactors and the like. Due to the high coolant temperature of metal-cooled reactors, the reactor core inlet temperature is typically above 300 ℃, the outlet temperature is above 500 ℃, and the bulk average power density is also 100MW/m³Therefore, the temperature of the fuel core of the fuel rod is high, and the operation safety of the reactor is influenced. At present, a liquid metal cooled reactor mainly adopts high-enrichment uranium dioxide fuel or uranium plutonium mixed oxide fuel, ceramic pellets and fuel rods, and the temperature of a fuel core is mainly controlled by reducing performance indexes of the reactor core and the like, such as reducing power density, average temperature of a coolant of the reactor core and the like, so that the performance of the small metal cooled reactor is seriously influenced. Therefore, it is very necessary to search for a novel fuel applied to a small metal-cooled reactor to reduce the temperature of the fuel core of the small metal-cooled fast reactor with high power density, improve the operation safety of the reactor, and fully exert the advantages of the small metal-cooled fast reactor in the aspects of long service life and high power density.

Disclosure of Invention

The invention aims to provide a granular fuel core, a fuel rod and a metal-cooled small reactor, and solves the problems that the fuel core of the existing liquid metal-cooled small reactor is high in temperature and affects the operation safety. Under the condition of ensuring that the average power density and the linear power density of the reactor core are not changed, the temperature of the core body of the fuel rod is reduced, and the operation safety of the reactor is improved.

The invention is realized by the following technical scheme:

a particle fuel core comprises a plurality of particle fuels, wherein the particle fuels are uniformly dispersed in a beryllium oxide matrix to form a high-thermal-conductivity fuel core body, each particle fuel consists of a fuel microsphere and a coating layer, the coating layer is coated on the outer side of the fuel microsphere, the coating layer is made of high-temperature-resistant high-thermal-conductivity silicon carbide, and the volume fraction of the fuel microsphere in the fuel core body is 30-60%; fission gas released by the fuel microspheres is contained through a coating layer and a beryllium oxide substrate, and the fuel microspheres are uranium dioxide or uranium plutonium mixed oxide.

The fuel rod with the core bodies as the particle fuel is adopted, the particle fuel adopts uranium dioxide or uranium plutonium mixed oxide as the fuel microspheres, and then high-temperature-resistant and high-thermal-conductivity silicon carbide (SiC) is used as a coating layer to coat the fuel microspheres, so that the heat conductivity of the fuel particles is improved; the fuel rod adopts a beryllium oxide material with thermal conductivity as a matrix, and the fuel particles are uniformly dispersed in the beryllium oxide matrix to form a fuel core body of the fuel rod. Fission gases from the nuclear fuel are contained by the particulate fuel coating and the fuel pellet matrix. Therefore, the invention can obviously improve the heat conductivity of the fuel core of the fuel rod and the heat conductivity coefficient between the fuel core and the outer surface of the rod element, thereby effectively reducing the temperature of the fuel core and obtaining greater operation safety of the reactor.

Further, the diameter of the pellet fuel was 1.0mm, and the thickness of the coating layer was 0.2 mm.

Further, the fuel rod comprises a cladding tube, the fuel core is arranged in the cladding tube and is in close contact with the cladding tube, and end plugs are arranged at two ends of the cladding tube.

The upper end and the lower end of the fuel rod are both provided with no air cavity, the fuel core body is tightly combined with the cladding, and the upper end and the lower end of the fuel core body are sealed by using the end plugs.

A metal cooled miniature reactor having a core comprising 103 fuel assemblies and 18 control rod assemblies uniformly staggered within the core, the fuel assemblies and control rod assemblies each comprising a fuel rod.

Further, the outer diameter of the fuel rod is 5.0 mm-7.0 mm.

Further, the fuel assembly comprises a plurality of fuel rods and an assembly box, wherein the fuel rods are arranged in the assembly box according to a regular triangular grid.

Furthermore, the control rod assembly comprises a plurality of fuel rods, a guide tube and an assembly box, wherein the guide tube is positioned at the central point of the control rod assembly, the fuel rods are uniformly arranged in the assembly box around the guide tube according to a regular triangle grid, and the control rods are arranged in the guide tube.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the nuclear fuel such as uranium dioxide or uranium plutonium mixed oxide is used as fuel microspheres, the fuel microspheres are coated by high-thermal-conductivity silicon carbide to form fuel particles with excellent thermal conductivity, and the fuel particles are dispersed in a beryllium oxide matrix with good thermal conductivity to form a high-temperature-resistant high-thermal-conductivity fuel core. In addition, the fuel rod is free of air cavities and air gaps, and the fuel core is in close contact with the cladding. Therefore, the invention obviously increases the heat conductivity of the fuel core and the heat conductivity coefficient between the fuel core and the outer surface of the fuel rod, thereby greatly reducing the average temperature of the fuel core and effectively improving the design performance and the operation safety of the metal cooling small reactor.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 is an axial schematic view of a fuel rod;

FIG. 2 is a radial schematic view of a piece of fuel rods;

FIG. 3 is a schematic illustration of a particulate fuel;

FIG. 4 is a schematic view of a control rod assembly;

FIG. 5 is a schematic view of a fuel assembly;

FIG. 6 is a schematic core layout.

Reference numbers and corresponding part names in the drawings:

1-granular fuel, 2-beryllium oxide matrix, 3-cladding tube, 4-end plug, 5-fuel microsphere, 6-cladding layer, 7-fuel rod, 8-assembly box, 9-guide tube, 10-control rod, 11-fuel assembly and 12-control rod assembly.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.