CN104766636B - A nested integrated structure of nuclear fuel rods and central cooling heat pipes - Google Patents

Abstract

The invention discloses the nested integral structure that a kind of nuclear fuel rod cools down heat pipe with center, including center cooling heat pipe, the nuclear fuel rod of positive six face column structure, the evaporator section of central cooling tube is placed in the core bore in the middle part of the nuclear fuel rod.Central cooling tube is followed successively by the porous wick structure, liquid ring cavity, tube wall that central steam area, porosity are 0.69 from inside to outside.Central steam area includes evaporator section, adiabatic section, condensation segment successively from bottom to top in the axial direction, and the length of evaporator section is consistent with the length of nuclear fuel rod.The inside of nuclear fuel rod is that fuel pellet, outside are involucrum, and the tube wall of the evaporator section of center cooling heat pipe is designed with the involucrum on the inside of nuclear fuel rod core bore to be integrated.0.1mm gap is left between fuel pellet and involucrum.Compact in design, safe, good reliability, are particularly suitable for use in nuclear reactor for space and the small-sized nuclear reactor of other specific uses.

Description

A nested integrated structure of nuclear fuel rods and central cooling heat pipes

technical field

The invention relates to nuclear power energy technology, in particular to a nested integrated structure of nuclear fuel rods and central cooling heat pipes.

Background technique

With the development and implementation of deep space exploration programs around the world, the construction of space bases on the surface of the moon and other planets in the future will have great scientific, military and political value. To establish space bases on the surface of the moon and other planets, the first thing that needs to be solved is the energy problem. However, solar cells and isotope batteries are difficult for space bases to meet the actual demand for high power. Therefore, space nuclear reactors have obvious advantages in the energy supply of future space bases.

The United States, Russia, Japan and other countries have all developed a strong interest in space nuclear reactors, researched and proposed dozens of space nuclear reactor system solutions, cooling methods include heat pipe cooling, liquid metal cooling, gas cooling, etc. Due to the complexity of the space base environment, the core of space nuclear reactors should adopt passive cooling technology. Heat pipe cooling has the best thermal transient feedback performance, the best reliability, and the lowest maintenance requirements. Therefore, most current space nuclear reactor designs use heat pipes. Cooling, the heat generated by the fuel rods is taken out of the core by the cooling heat pipe, and then provided with energy supply through the energy conversion system.

As shown in Figure 3a, in the existing space nuclear reactor design, the fuel rods and cooling heat pipes are made into cylindrical shapes with the same outer diameter, and the fuel rods and cooling heat pipes are arranged adjacently. However, due to the constraints of the geometric shape of the heat pipes in this arrangement, there must be a gap between the fuel rods and the heat pipes, resulting in a low fuel filling rate, and the gap between the fuel rods and the cooling heat pipes is filled with structural materials, resulting in a nuclear reactor. Critical mass and increase in total core mass.

Contents of the invention

The object of the present invention is to provide a nested integrated structure of nuclear fuel rods and central cooling heat pipes with compact layout, high safety and good reliability.

The purpose of the present invention is achieved through the following technical solutions:

The nested integrated structure of nuclear fuel rods and central cooling heat pipes of the present invention includes central cooling heat pipes and nuclear fuel rods, and the evaporation section of the central cooling pipes is placed in the core hole in the middle of the nuclear fuel rods.

It can be seen from the above-mentioned technical solution provided by the present invention that in the nested integrated structure of the nuclear fuel rod and the central cooling heat pipe provided by the embodiment of the present invention, since the evaporation section of the central cooling pipe is placed in the core hole in the middle of the nuclear fuel rod, With compact layout, high safety and good reliability, it is especially suitable for space nuclear reactors and other small nuclear reactors for special purposes.

Description of drawings

Fig. 1 is a schematic diagram of a radial cross-sectional structure of a nested integrated structure of a nuclear fuel rod and a central cooling heat pipe provided by an embodiment of the present invention;

Figure 2 is a schematic diagram of an axial cross-sectional structure of a nested integrated structure of a nuclear fuel rod and a central cooling heat pipe provided by an embodiment of the present invention;

Figure 3a is a schematic diagram of the arrangement of nuclear fuel rods and cooling heat pipes used in the prior art;

Fig. 3b is a schematic layout diagram of the nested integrated structure of nuclear fuel rods and central cooling heat pipes applied to the core design provided by the embodiment of the present invention.

In the picture:

1. Fuel pellets, 2. Cladding, 3. Liquid annular cavity, 4. Porous liquid-absorbing core, 5. Central vapor zone, 6. Evaporation section, 7. Insulation section, 8. Condensation section, 9. Nuclear fuel rod, 10. Central cooling heat pipe (or cooling heat pipe).

detailed description

The embodiments of the present invention will be further described in detail below.

The nested integrated structure of the nuclear fuel rod and the central cooling heat pipe of the present invention, its preferred embodiment is:

It includes a central cooling heat pipe and a nuclear fuel rod, and the evaporation section of the central cooling pipe is placed in a core hole in the middle of the nuclear fuel rod.

The central cooling pipe consists of a central steam area, a porous liquid-absorbing core, a liquid annular cavity, and a pipe wall from the inside to the outside.

The central steam zone includes an evaporation section, an adiabatic section, and a condensation section sequentially from the bottom to the top in the axial direction, and the length of the evaporation section is consistent with the length of the nuclear fuel rod.

The porosity of the porous wick was 0.69.

The inside of the nuclear fuel rod is a fuel pellet, and the outside is a cladding, and the tube wall of the evaporation section of the central cooling heat pipe is integrated with the cladding inside the core hole of the nuclear fuel rod.

A gap of 0.1 mm is left between the fuel pellets and the cladding.

The nuclear fuel rod is a regular hexahedron structure.

The nested integrated structure of nuclear fuel rods and central cooling heat pipes of the present invention overcomes the shortcomings of the prior art, and has compact layout, high safety and good reliability, and is especially suitable for space nuclear reactors and other small nuclear reactors for special purposes. The nested integrated structure of nuclear fuel rods and central cooling heat pipes can be closely arranged in the reactor core, effectively increasing the fuel filling degree of the core, reducing the critical mass of the core, thereby reducing the use of structural materials and shielding materials , reducing the total mass of the core; at the same time, the relative density of the heat pipe arrangement is increased, which can effectively avoid the problems caused by the failure of a single heat pipe, and has high reliability. The invention realizes the nested integrated structure design of nuclear fuel rods and central cooling heat pipes, adopts a passive compact design, and can effectively improve the safety and reliability of the reactor.

The evaporation section of the central cooling heat pipe absorbs the heat generated by the fuel pellets, and takes the heat out of the core through the adiabatic section and the condensation section of the central cooling heat pipe. A gap of 0.1 mm is left between the fuel pellet and the cladding to accommodate fission gas.

Compared with prior art, the beneficial effect of the present invention is:

(1) The nuclear fuel rods are regular hexahedrons and can be compactly arranged, thereby increasing the fuel filling degree, reducing the critical mass of the nuclear reactor, and reducing the core volume.

(2) The use of structural materials and shielding materials is reduced, and the core quality is reduced.

(3) The relative density of heat pipe arrangement is increased, which can effectively avoid problems caused by the failure of a single heat pipe, and has high reliability.

Specific examples:

Taking the core design of a space nuclear reactor as an example, the design life of nuclear fuel rods and central cooling heat pipes is based on the core life, and there is no need to replace them during the core life.

As shown in accompanying drawings 1 and 2, the central cooling heat pipe 10 is placed in the center of the nuclear fuel rod 9, and the evaporation section 6 of the central cooling heat pipe is consistent with the length of the nuclear fuel rod. The evaporation section 6 of the central cooling heat pipe absorbs the heat generated by the fuel pellet 1 and passes through the center Cooling heat pipe adiabatic section 7 and condensing section 8 take heat out of the core. Inside the nuclear fuel rod 9 is a fuel pellet 1 , and outside the nuclear fuel rod 9 is a fuel rod cladding 2 . A gap of 0.1 mm is left between the fuel pellet and the cladding to accommodate fission gas. The shell of the central cooling heat pipe is integrated with the inner cladding of the nuclear fuel rod. Inside the tube is a porous liquid-absorbing core 4 with a porosity of 0.69.

The effect of the present invention applied to the core design of a space nuclear reactor is shown in Figure 3b. The layout of fuel rods and cooling heat pipes is more compact than the core design in the prior art shown in Figure 3a, which improves the fuel filling rate and reduces The critical mass of the nuclear reactor reduces the volume of the core, and also reduces the use of structural materials and shielding materials, reducing the quality of the core. Moreover, the relative density of heat pipe arrangement increases, which can effectively avoid problems caused by failure of a single heat pipe, and has high reliability.

The parts not described in detail in the present invention belong to the known technology in the art.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field can easily conceive of changes or changes within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (3)

1. A nested integrated structure of a nuclear fuel rod and a central cooling heat pipe, characterized in that it includes a central cooling heat pipe and a nuclear fuel rod, and the evaporation section of the central cooling pipe is placed in the core hole in the middle of the nuclear fuel rod; The central cooling pipe is sequentially composed of a central steam area, a porous liquid-absorbing core, a liquid annular cavity, and a pipe wall from the inside to the outside; The central steam zone includes an evaporation section, an adiabatic section, and a condensation section sequentially from the bottom to the top in the axial direction, and the length of the evaporation section is consistent with the length of the nuclear fuel rod; The inside of the nuclear fuel rod is a fuel pellet, and the outside is a cladding, and the tube wall of the evaporation section of the central cooling heat pipe is designed as one with the cladding inside the core hole of the nuclear fuel rod; The nuclear fuel rod is a regular hexahedron structure. 2. The nested integrated structure of nuclear fuel rods and central cooling heat pipes according to claim 1, characterized in that the porosity of the porous liquid-absorbing core is 0.69. 3. The nested integrated structure of nuclear fuel rods and central cooling heat pipes according to claim 1 or 2, characterized in that there is a gap of 0.1 mm between the fuel pellets and the cladding.