CN111477354A - Co-extrusion annular fuel rod - Google Patents

Abstract

The invention relates to the technical field of nuclear fuel, and specifically discloses a co-extruded annular fuel rod, in which there is no gap between the fuel pellet and the cladding, the heat conduction is enhanced, the center temperature of the fuel pellet is lowered, and the traditional fuel pellet is no longer required. The compression spring structure increases the stability of operation and reduces radioactive waste. The fuel rod structure of the present invention simplifies the assembly and manufacturing process of the fuel rod, does not need to fill the inside of the fuel rod with helium gas during manufacture, and reduces the cost.

Description

A co-extruded annular fuel rod

technical field

The invention belongs to the technical field of nuclear fuel, and in particular relates to a co-extruded annular fuel rod.

Background technique

During the operation of a nuclear power plant reactor, the performance of nuclear fuel is an important factor affecting the safety and economy of the reactor. Therefore, the research on fuel elements has been placed in a very prominent position in the world. By optimizing the design of fuel elements, adopting advanced structural materials, and improving the manufacturing process of elements, the various properties of nuclear fuel elements have been continuously improved, and nuclear power has been promoted to be safer and more efficient. direction of economic development.

Usually nuclear fuel is designed as a solid cylinder, which consists of upper and lower end plugs, pellets, compression springs and cladding. The coolant flows through the cladding to cool the fuel rods.

Compared to conventional solid cylindrical fuels, the benefits of annular fuels are that at very high linear power densities, the temperature in the center of the fuel remains low, there is less energy storage within the fuel, and less fission gas is released. Better fuel performance can be expected under normal operation and transient conditions.

In the existing annular fuel rod, there are gaps between the outer surface of the inner cladding shell and the inner surface of the annular fuel pellet, and between the inner surface of the outer cladding and the outer surface of the annular fuel pellet, which is not conducive to the annular fuel pellet. The heat dissipation is high, and the assembly process precision is high, which is inconvenient for assembly and processing.

In the existing sodium-cooled fast reactor fuel elements, the outer surface of the fuel rod cladding tube generally adopts a wire-wound positioning structure to laterally position the fuel rods inside the assembly, and the coolant is subjected to the lateral force of the wire-wound to generate a lateral flow, so that the The heat from the cladding surface is better transferred to the central area of the coolant, effectively reducing the maximum temperature of the fuel rod cladding surface and ensuring the safety of the assembly. However, due to the inevitable gap between the winding wire and the outer surface of the fuel rod cladding tube, vibration is easily generated between the winding wire and the outer surface of the fuel rod cladding tube, which affects the stability of the structure, and the contact part between the winding wire and the fuel rod is The coolant flow area is long and narrow, and there will be vortices and flow stagnation areas on the backflow surface of the winding wire to the coolant, which will also hinder the conduction of heat.

Therefore, there is an urgent need to design a fuel rod that can eliminate the above-mentioned defects.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a co-extruded annular fuel rod, which eliminates the gap between the fuel pellet and the cladding and optimizes the heat transfer effect of the contact portion between the winding wire and the fuel rod.

The technical scheme of the present invention is as follows:

A co-extruded annular fuel rod, comprising an upper end plug, a lower end plug, an inner cladding, an outer cladding, and an annular fuel core;

The annular fuel core body, the inner cladding shell and the outer shell are processed by co-extrusion, and there is no gap between each other, which enhances heat conduction and reduces the core temperature;

An upper end plug is connected to the upper part of the inner envelope and the outer envelope, and a lower end plug is connected to the lower part.

It also includes that N pieces of spoiler wings are processed on the outer surface of the outer casing, and N≧1.

The spoiler wings are helically distributed on the outer surface of the outer casing.

The spoiler and the outer surface of the outer casing are integrally processed and formed, which can significantly increase the heat exchange area, which is beneficial to the overall heat dissipation, and at the same time eliminates the local heat of the cladding caused by the poor heat transfer effect between the wire winding positioning structure and the surface of the fuel rod. The phenomenon of poor heat transfer effect.

When there are multiple spoiler wings, they are distributed on the outer surface of the outer casing along the axial direction at equal angles.

The height of the spoiler is equal to the distance between two adjacent annular fuel rods in the fuel assembly, and the two adjacent annular fuel rods can be limited by the spoiler.

The inside of the fuel rod does not need to be filled with helium.

The annular fuel core is a dispersion fuel.

The annular fuel core is metal fuel.

It is suitable for pressurized water reactor, fast reactor, low temperature heating reactor, space reactor, boiling water reactor, micro reactor, zero power reactor, heavy water reactor, power reactor and marine power reactor.

The remarkable effect of the present invention is:

(1) There is no gap between the fuel pellet and the cladding of the fuel rod of the present invention, which enhances heat conduction, reduces the central temperature of the fuel pellet, and no longer needs the traditional compression spring structure, which increases the stability of operation and reduces the radioactive waste.

(2) The spoiler structure of the present invention is integrally formed with the outer casing of the fuel rod, and there is no gap between them. Compared with the wire-wound positioning structure, the heat exchange area can be significantly increased, which is beneficial to the overall heat dissipation.

(3) The spoiler structure of the fuel rod of the present invention can significantly enhance the lateral stirring effect.

(4) The fuel rod structure of the present invention simplifies the assembly and manufacturing process of the fuel rod, and does not need to fill the inside of the fuel rod with helium gas during manufacture, thereby reducing the cost.

Description of drawings

Fig. 1 is a schematic cross-sectional view of a co-extruded annular fuel rod undisturbed airfoil;

Fig. 2 is a schematic diagram of a longitudinal section of a co-extruded annular fuel rod undisturbed airfoil;

Figure 3 is a schematic cross-sectional view of a co-extruded annular fuel rod with spoiler wings;

Fig. 4 is a schematic diagram of a longitudinal section of a co-extruded annular fuel rod with a spoiler;

FIG. 5 is a schematic cross-sectional view of a co-extruded annular fuel rod multi-spoiler wing.

In the figure: 1. Upper end plug; 2. Lower end plug; 3. Inner cladding; 4. Outer cladding; 5. Annular fuel core; 6. Spoiler.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

As shown in FIGS. 1 and 2 , a co-extruded annular fuel rod includes an upper end plug 1 , a lower end plug 2 , an inner cladding 3 , an outer cladding 4 , and an annular fuel core 5 .

The annular fuel core 5, the inner cladding 3 and the outer cladding 4 are processed by co-extrusion, and there is no gap between each other, which enhances heat conduction and reduces the central temperature of the fuel pellet.

The upper end plug 1 is connected to the upper part of the inner casing 3 and the outer casing 4 , and the lower end plug 2 is connected to the lower part.

The annular fuel core 5 is a dispersion or metal fuel.

The traditional co-extrusion processing method is prone to cause uneven distribution of cores at both ends of the co-extrusion. Therefore, after the co-extruded annular fuel rod of the present application is cut off the uneven parts of the cores at both ends, Then weld the upper end plug 1 and the lower end plug 2 respectively.

As shown in FIGS. 3 and 4 , N spoiler fins 6 are processed on the outer surface of the outer casing 4 , and N≧0. The spoiler 6 is spirally distributed on the outer surface of the outer casing 4, and is integrally processed and formed with the outer surface of the outer casing 4, which can significantly increase the heat exchange area, which is beneficial to the overall heat dissipation, and at the same time eliminates the difference between the winding positioning structure and the outer casing. The phenomenon that the local heat transfer effect of the cladding is poor due to the poor heat transfer effect of the contact part of the fuel rod surface.

As shown in FIG. 5 , when there are multiple spoiler wings 6 , they are distributed on the outer surface of the outer casing 4 at equal angles along the axial direction. The height of the spoiler 6 is equal to the distance between two adjacent annular fuel rods in the fuel assembly, and the two adjacent annular fuel rods can be limited by the spoiler 6 .

The co-extruded annular fuel rod of the present invention is suitable for pressurized water reactor, fast reactor, low temperature heating reactor, space reactor, boiling water reactor, micro reactor, zero power reactor, heavy water reactor, power reactor and marine power Heap type.

Claims (10)

1. A co-extruded annular fuel rod characterized by: comprises an upper end plug (1), a lower end plug (2), an inner packing shell (3), an outer packing shell (4) and an annular fuel core body (5);

the annular fuel core (5), the inner cladding (3) and the outer cladding (4) are processed in a co-extrusion mode, no gap exists between the annular fuel core and the inner cladding, heat conduction is enhanced, and central temperature is reduced;

an upper end plug (1) is connected above the inner cladding (3) and the outer cladding (4), and a lower end plug (2) is connected below the inner cladding and the outer cladding.

2. A co-extruded annular fuel rod of claim 1 wherein: the outer surface of the outer casing (4) is provided with N turbulence wings (6), wherein N is more than or equal to 1.

3. A co-extruded annular fuel rod of claim 2 wherein: the turbulence wings (6) are spirally distributed on the outer surface of the outer cladding (4).

4. A co-extruded annular fuel rod of claim 3 wherein: the turbulence wings (6) and the outer surface of the outer wrapping shell (4) are integrally processed and formed, so that the heat exchange area can be obviously increased, the whole heat dissipation is facilitated, and the phenomenon of poor heat transfer effect of local heat of the cladding caused by poor heat transfer effect of the contact part of the wire winding positioning structure and the surface of the fuel rod is eliminated.

5. A co-extruded annular fuel rod of claim 4 wherein: when the number of the turbulence wings (6) is multiple, the turbulence wings are distributed on the outer surface of the outer casing (4) at equal angles along the axial direction.

6. A co-extruded annular fuel rod of claim 5 wherein: the height of the turbulence wing (6) is equal to the distance between two adjacent annular fuel rods in the fuel assembly, and the two adjacent annular fuel rods can be limited through the turbulence wing (6).

7. A co-extruded annular fuel rod of claim 6 wherein: helium does not need to be filled in the fuel rod.

8. A co-extruded annular fuel rod of claim 7 wherein: the annular fuel core (5) is a dispersion fuel.

9. A co-extruded annular fuel rod of claim 7 wherein: the annular fuel core (5) is metal fuel.

10. A co-extruded annular fuel rod as claimed in any one of claims 1 to 9, wherein: the reactor is suitable for pressurized water reactors, fast reactors, low-temperature heat supply reactors, space reactors, boiling water reactors, micro-reactors, zero-power reactors, heavy water reactors, power reactors and marine power reactor types.

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