JPS62130383A - Heat receiving plate for nuclear fusion device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a first wall, a diverter plate, a limiter plate, etc. (hereinafter referred to as a heat receiving plate) that receives heat load and particle load from plasma in a nuclear fusion device. It concerns structural improvements.

[Technical background of the invention and its problems]

The heat receiving plate of a fusion device is subjected to a large heat load and particle load from the plasma. Since the heat receiving plate is worn out by sputtering due to incident particles from the plasma, the material of the heat receiving plate needs to be a material with a low sputtering rate, that is, a material with a small amount of surface wear. Furthermore, in order to remove the high heat load from the plasma, the heat receiving plate requires a cooling device. Therefore, as shown in Fig. 4, a conventional heat receiving plate is provided with a plasma-side surface material 4 made of a material with a high melting point and a low sputtering rate above the cooling tube 2 made of high thermal conductivity such as copper, and is designed to absorb the incident light from the plasma. This prevents wear and tear caused by particles 1. As the surface material on the plasma side, graphite, SiC, and ceramics such as those disclosed in Japanese Patent Application Laid-Open No. 59-151084 are used.

The problem with the conventional structure shown in FIG. 4 is thermal stress at the joint between the cooling pipe 2 and the plasma side surface material 4. The thermal expansion coefficient of the copper of the cooling pipe 2 is the same as that of the graphite, SiC plasma side surface material 4.
It is 3 to 4 times the amount. Therefore.

When the cooling pipe 2 and the plasma-side surface material 4 are bonded together by brazing or the like, a large residual stress is generated at the bonded portion. This residual stress may cause cracks in the joint between the cooling pipe 2 and the plasma side surface material 4, or may cause destruction of the plasma side surface material 4, which is generally considered to be a brittle material. Even if the bonding is successful, if a high heat load is applied to the heat receiving plate from the plasma, a large thermal stress will be generated in the bonded portion due to the difference in thermal elongation between the cooling pipe 2 and the plasma side surface material 4. In a tokamak-type fusion device, the thermal load from the plasma is usually a repetitive load, so this thermal stress is a repetitive stress. Due to this repeated stress, the cooling pipe 2 and the plasma side surface material 4 may be destroyed.
There is a high risk that the joints will burst.

Furthermore, in the case of the plasma side surface material 4 made of a low atomic number material such as graphite or SiC, there is a possibility that the surface temperature thereof exceeds the allowable temperature of the material. That is, the thermal conductivity of these nonmetallic low atomic number materials is 174 to 1710 that of copper at high temperatures of several hundred degrees Celsius, and is even lower in the neutron irradiation environment of a nuclear fusion device. Because of this low thermal conductivity, when the plasma side surface material 4 is made thicker in order to have a longer service life against wear and tear due to sputtering, it becomes difficult to keep the surface temperature below the allowable value. In addition, there is a problem that the thermal stress of the heat receiving plate becomes large.6 [Object of the Invention] The present invention provides a long-life heat receiving plate that has little thermal stress, has a gentle temperature distribution on the plasma side surface material, and is highly reliable. The purpose is to

[Summary of the invention]

The heat receiving plate of the present invention is a plasma-side surface material provided on a cooling tube, and is a mixture of a metal with a high melting point and low sputtering rate, such as graphite or SiC, and a metal with high thermal conductivity, such as copper, and is integrated under pressure. This is achieved by creating a structure that allows

[Embodiments of the invention]

Hereinafter, one embodiment of a heat receiving plate of a nuclear fusion device according to the present invention will be described with reference to FIG.

In the heat receiving plate shown in FIG. 1, 2 is a cooling pipe made of copper or the like, and 3 is a plasma side surface material.

The plasma side surface material 3 is made of a metal 3b with high thermal conductivity such as copper and a metal 3 with a low sputtering rate such as graphite or SiC.
It is formed from a mixed layer of a.

The cooling pipe 2 and the plasma-side surface material 3 are joined by brazing, casting, or the like.

The operation of the present invention will be explained. Since the plasma side surface material 3 contains the metal 3b having high thermal conductivity, its thermal conductivity is higher than that of a conventional plasma side surface material made only of a low sputtering material. Therefore, according to the present invention, the temperature distribution within the plasma side surface material 3 can be made gentler and the surface temperature can be lowered compared to the conventional heat receiving plate.

Since the plasma side surface material 3 contains a metal 3b having high thermal conductivity such as copper having a large coefficient of thermal expansion, the difference in coefficient of thermal expansion between it and the cooling pipe 2 is smaller than that of a conventional heat receiving plate. Also,
The plasma side surface material 3 has increased ductility and is stronger than low-strength materials such as graphite. Therefore, according to the present invention, thermal stress due to differences in thermal elongation can be alleviated, thereby preventing damage due to thermal stress. , it is possible to extend the life of the heat receiving plate.

FIG. 3 shows the results of calculating the average coefficient of thermal expansion of the plasma side surface material 3 according to the present invention using the following Tunner & Kerner equation.

α. = ΣαnKnvn/ΣKnV.

Here, K: Vertical modulus of elasticity α of the constituent material: Coefficient of thermal expansion V2 volume content α of the constituent material. :In the thermal expansion coefficient of the composite material in Figure 3, the K of copper is 10,600 kg/mm",
rx 16.5X10-”/'C, graphite K
806kg/pus 2゜α5. It shows α and the volume content of copper when ILX10''''1°C. Even if only a few percent of copper is contained, the average coefficient of thermal expansion becomes very large.

Next, another embodiment will be described with reference to FIG.

The heat receiving plate shown in FIG. 2 includes a high melting point, low sputtering material 3a and a high thermal conductivity metal 3b in the plasma side surface material 3.
The proportions of these changes depending on location. That is, near the joint surface with the cooling pipe 2, the metal 3b with high thermal conductivity
The ratio of metal 3b having high thermal conductivity is increased, and the ratio of metal 3b having high thermal conductivity is decreased as the distance from the joint surface increases. With this configuration, a layer consisting only of the high melting point, low sputtering material 3a can be formed on the surface that receives the thermal load of one particle from the plasma, so that wear due to sputtering can be reduced. Further, it is possible to prevent the metal 3b having high thermal conductivity from being mixed into the plasma. Therefore, this configuration is effective when it is necessary to use a material with a low atomic number for the plasma side surface material in order to reduce the amount of heat radiation from the plasma due to mixed impurities. Note that, like the previous embodiment, this embodiment can alleviate thermal stress near the bonding surface.

It is possible to prevent damage to the heat receiving plate and extend its life.

〔Effect of the invention〕

As described above, according to the present invention, thermal stress due to differences in thermal elongation can be alleviated, so damage to the heat receiving plate due to thermal stress can be prevented and the life of the heat receiving plate can be extended. Furthermore, since the thermal conductivity of the plasma-side surface material can be increased, the temperature distribution within the plasma-side surface material can be made gentle and the surface temperature can be lowered. As a result, even when the thickness of the plasma-side surface material is increased so as to have a long life against wear and tear due to sputtering, the surface temperature can be kept below the allowable value. In addition, it is possible to provide a highly reliable and long-life fusion device heat receiving plate.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a heat receiving plate of a nuclear fusion device according to an embodiment of the present invention, FIG. 2 is a sectional view of another embodiment of the present invention, and FIG. 3 is a plasma side surface material of a heat receiving plate according to the present invention. FIG. 4 is a curve diagram showing the relationship between the average coefficient of thermal expansion and the volume content of copper, and FIG. 4 is a cross-sectional view of a conventional heat receiving plate. 1... Heat load from plasma 1 Particle load 2... Cooling pipe 3... Plasma side surface material according to the present invention 3a... Low sputtering material 3b... High thermal conductivity metal 4... Conventional Plasma side surface material agent Patent attorney Nori Chika Ken Yudo Hirofumi Mitsumata 111111~ / Figure 1 Figure 2 411A447m 斯萩 [1 Figure 3 Figure 4vA

Claims (2)

[Claims] (1) Nuclear fusion characterized by comprising a surface material that is a mixture of a material with a high melting point and low sputtering rate and a metal with high thermal conductivity and integrated under pressure, and a cooling pipe joined to this surface material. Heat receiving plate of the device. (2) The content of high thermal conductivity metal in the surface material is
2. The heat receiving plate for a nuclear fusion device according to claim 1, wherein the heat receiving plate for a nuclear fusion device according to claim 1 is higher at the interface with the cooling pipe than at the surface receiving the particle load.