JPS61104291A - Vacuum vessel for nuclear fusion device and manufacture thereof - 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 [Field of Application of the Invention] The present invention relates to a novel vacuum vessel for a nuclear fusion device, and particularly to the reactor wall structure of the vacuum vessel. The present invention also relates to a method for manufacturing such a vacuum container.

[Background of the invention]

As a nuclear fusion device, for example, a torus type nuclear fusion device is provided with a substantially annular vacuum vessel that confines plasma therein. In the vacuum container, a plurality of toroidal magnetic field coils that generate a magnetic field for holding plasma in a predetermined space surround the vacuum container, and are arranged at predetermined intervals in the length direction of the annular shape. Furthermore, a plurality of voloidal magnetic field coils are arranged along the vacuum vessel to perform Joule heating of the plasma and to generate a magnetic field for controlling the position of the plasma.

In such a nuclear fusion device, it is necessary to confine high-temperature plasma reaching approximately 100 million degrees Celsius in a vacuum container. In order to protect the vacuum vessel from such high-temperature plasma, a third wall is provided at a position directly facing the plasma. Furthermore, a limiter, a diverter, etc. are provided to protect the third wall in the event of an abnormality. Therefore, the third wall, divertor, etc. are used under severe conditions such as wear and tear due to interaction with plasma particles in a high vacuum, and irradiation with high-energy neutrons and gamma rays generated in nuclear fusion reactions. For this reason, MO, W, or the like having a high melting point is traditionally fixed to a metal body of the cooling structure with bolts, as described in Japanese Patent Publication No. 55-94181.

Since MO, ~V, etc. have a relatively large atomic number, they have a disadvantage of poor so-called impurity characteristics in which sputtered atoms enter the plasma particles and lower the plasma temperature.

Furthermore, since MO, W, etc. are fixed to a metal base with bolts, the cooling capacity is small and in a nuclear fusion device exposed to high heat, the above-mentioned impurity characteristics are further deteriorated.

For this reason, a furnace wall with a laminated structure in which a ceramic having a small atomic number is metallurgically bonded to the metal substrate is desired.

However, conventionally, when metallurgically joining ceramics and metals, the physical properties of the two materials, especially the coefficient of thermal expansion, are significantly different, so the joining process or...

Thermal stress occurs under convenient conditions under thermal load,
Thermal stress fracture occurs in ceramics or joints. This thermal stress fracture becomes more pronounced as the ceramic and metal substrates become larger, and it has been extremely difficult to metallurgically bond ceramics to large metal substrates such as the furnace wall of a vacuum vessel.

Conventionally, as a method for preventing thermal stress fracture of ceramics, Mo, W, and Kovar, which have a coefficient of thermal expansion approximately intermediate between ceramics and metals, have been used.

Bonding is performed using a thermal stress relieving material such as Fanny.

For example, JP-A-58-176182 describes the use of Kovar or 42Ni alloy bodies as thermal stress relaxation materials.

However, when bonding ceramics and metals using such conventional methods, not only is there a limit to the size of the ceramics, but especially when the coefficient of thermal expansion is 3 to 4 x 10-'/lel'
In the case of small non-oxide ceramics, bonding was impossible.

On the other hand, since ceramics generally have low thermal conductivity, a furnace wall structure that enhances the cooling effect of ceramics is desired.

[Purpose of the invention]

An object of the present invention is to provide a vacuum vessel for a nuclear fusion device having a laminated structure of ceramics and a metal substrate, which has low thermal stress and excellent cooling properties, and a method for manufacturing the same.

[Summary of the invention]

The present invention provides a vacuum vessel for a nuclear fusion device, in which a furnace wall constituting the inside of the vacuum vessel exposed to plasma particles is formed by metallurgical bonding between a large number of divided heat-resistant ceramic tiles and a metal base having a cooling structure. It has a laminated structure,
The vacuum vessel for a nuclear fusion device is characterized in that the ceramic tile and the metal base are metallurgically joined via a hollow metal member having an intermediate coefficient of thermal expansion.

Specifically, by bonding a ceramic tile to one end of the hollow metal member and bonding the other end of the hollow metal member to a large metal base, heat can be reduced due to the difference in thermal expansion coefficient between the large metal base and the ceramic. It is designed to reduce stress and prevent thermal stress fracture.

In addition, in order to obtain the above-mentioned vacuum container, the hollow metal member and the ceramics are connected metallurgically via an intermediate having a coefficient of thermal expansion between that of the hollow metal member and the ceramics on one end side of the hollow metal member. The other end of the hollow metal member is then metallurgically joined to a large metal body.

[Embodiments of the invention]

Figure WJ1 is a sectional view of a vacuum vessel showing an embodiment of the ceramic tiled metal laminate structure according to the present invention, and Figure 2 is a perspective view thereof. In FIGS. 1 and 2, a furnace wall 10 has a tile-shaped ceramic 12 disposed on its inner surface, and this ceramic 12 is metallurgically joined to a hollow metal member 16 via an intermediate body 14. There is.

The intermediate body 14 has a coefficient of thermal expansion between that of the hollow metal member 16 and the ceramic 12, and is intended to reduce thermal stress due to the difference in coefficient of thermal expansion between the two. The hollow metal member 16 is formed into a ring shape whose outer diameter is slightly smaller than the vertical or horizontal dimensions of the ceramic 12, and the ring at the other end, which is joined to the ceramic, is inserted into a joining hole drilled in the large metal base 20. It is inserted and metallurgically joined to the large metal base 20 by the joining portion 22 . A metal plate 24 is metallurgically or mechanically bonded to the large metal base 20. This metal plate 24 has a convex portion 2
By providing 6, a coolant passage 28 is formed.

Therefore, the hollow portion 30 of the hollow metal member 16 communicates with the coolant passage.

The furnace wall body 10 of the nine vacuum vessels constructed as described above has the ceramic 12 and the large metal base 20 joined to the hollow metal member 1.
6, the ceramics 12 and the large metal substrate 20 are not directly bonded, and even when a plurality of ceramics 12 are bonded to the large metal substrate 20 in the form of tiles, the thermal stress is extremely small. 12 thermal stress failure does not occur. Furthermore, since the hollow portion 30 of the hollow metal member 16 and the coolant flow path 28 are in communication, the ceramics 12 can be forcibly and efficiently cooled by the coolant flowing through the coolant flow path 28. Therefore, even when a large thermal load is applied to the ceramic surface, thermal damage to the ceramic 12 can be prevented.

FIG. 3 is a perspective view showing a bonded state between the ceramic 12 and the hollow metal member 16, and FIG. 4 is a sectional view. It is preferable that the ceramic 12 and the hollow metal member 16 be bonded via the intermediate body 14 having a coefficient of thermal expansion t- which is approximately intermediate between that of the ceramic 12 and the hollow metal member 16, as described above. The ceramic 12 and the intermediate body 14 can be bonded by metalizing the surface of the ceramic 120 in advance and using a brazing material 32 such as silver solder. In addition, intermediate 14
The hollow metal member 16 can be joined to the hollow metal member 16 through a brazing material 34.

As shown in FIG. 5, the hollow metal member 16 has a hollow portion 30.
It is desirable to form the bottom portion 36 integrally with the ring portion 16 so that the hole is a bottomed hole.

This hollow metal member is preferably cylindrical, particularly preferably cylindrical.

On the other hand, the intermediate body 14 is preferably a composite material of carbon fiber and copper. Since this composite material has a higher thermal conductivity than Furniture, Copal, etc., it is possible to greatly increase the cooling effect compared to conventional materials.

Composite materials of carbon fiber and copper are made by bundling multiple copper-coated carbon fibers and weaving them two-dimensionally.
It can be formed by firing while applying pressure at 0C. The composite used for the intermediate body 14 is made of ceramic by changing the coefficient of thermal expansion continuously or stepwise in the thickness direction so that the coefficient of thermal expansion is smaller on the ceramic side and larger on the hollow metal member 16 side. Thermal stress generated in the structure 12 can be further reduced. The coefficient of thermal expansion of the composite body can be changed continuously or stepwise in the thickness direction by laminating the carbon fibers so that the volume coefficients of the carbon fibers are different in the thickness direction.

When joining non-oxide ceramics such as 8iC, 5inN4 to stainless steel or steel, the coefficient of thermal expansion of the intermediate body 14 changes continuously or stepwise between 4 and 12 x 10-'IC. is desirable.

In such an intermediate body 14, the carbon fiber volume in the composite is 50 to 6 in the first layer on the ceramic 12 side.
It can be obtained by stacking the layers so that the second layer has a thickness of 30 to 40. The longitudinal elastic modulus of the thus obtained composite material at room temperature is 8 to 10 x 10
"b/M", thermal conductivity is 0.4-0.5 ca
t/cm-s-C.

When the intermediate body 14 has a laminated structure of carbon fiber coated with copper, the hollow metal member 16 is attached to the bottom part 3 as shown in FIG.
It is desirable that it be formed integrally with 6.

In this case, the joining method is to metalize the surface of ceramic 12 in advance, and then use the brazing filler metal 32.34 to
and the hollow metal member 16 can be joined via the intermediate body 14.

Note that depending on the type of ceramics, it is possible to join them using a brazing filler metal 32.degree. 34 without metalizing the surface of the ceramics in advance.

On the other hand, the hollow metal member 16 and the large metal base 2o are joined together after the hollow metal member 16 is inserted into the joint hole formed in the large metal base 20, as shown in FIGS. 6 and 7.
f: Performed by forming. Therefore, since the hollow metal member of the ceramic 12 is not directly joined to the large metal base 20, a large number of ceramics can be joined to the large metal base 20 in the form of tiles without destroying the ceramic 12. Note that if the large metal base 20 is extremely thick, it is extremely difficult to bond the ceramic 12 and the hollow metal member 16 and to bond the hollow metal member 16 and the metal base 20 to the metal base 20 at the same time. In such a case,
Ceramic 12 and intermediate metal member 1 via intermediate body 14
6, the hollow metal member 16 and the large metal base 2 are joined together.
0 by a melting method that allows local heating. It is preferable to use an arc, plasma, electron beam, laser, etc. as the heat source for this fusion bonding method using local knife-edge heat, and it is best to use an electron beam or laser as the heat source in terms of minimizing thermal distortion. desirable. Furthermore, joining can also be achieved by local brazing using a local heating source.
.

FIG. 8 shows a state in which the hollow metal member 16 and the large metal base 20 are joined using the turtle beam 38. The electron beam 38 is rotated in a circular manner to form a joint 22 around the circumference of the hollow metal member 16 . As shown in Figure 8, there are gaps between the ceramic tiles.
A small gap 1931 is formed, and by forming the bent portion 40 in the thickness direction of this gap, leakage of heat inside the furnace to the outside can be reduced, and the thermal efficiency of the furnace can be increased.

Furthermore, when radiation is generated within the reactor, leakage of radiation is reduced and safety can be improved. The formation of this gap also has the effect of preventing damage to the ceramics due to thermal expansion. Note that when the minute gap 31 is linear, leakage of heat and radiation can be reduced by filling the minute gap.

Furthermore, in the embodiment shown in FIG.
A groove 42 into which 6 is inserted is formed. By fitting the convex portion 26 of the metal plate 24 into the groove 42 in this manner, the coolant flow path 28 can be reliably formed at a predetermined position. Note that the groove 42 may be formed by attaching a U-shaped metal member to the large metal frame 20 shown in FIG. 1 or 7.

On the other hand, the above-mentioned ceramics are preferably made of elements with low atomic numbers, and more preferably have high electrical resistance and high thermal conductivity. In particular, a sintered body containing at least one of silicon carbide and beryllium compounds with an amount of 0.1 to 5 tqb or more of silicon carbide in an amount of 0.4 cat at room temperature - sec 7: It is a preferred ceramic having a high thermal conductivity of 10'9m or more and an electrical resistivity of 10'9m or more at room temperature.

Example 1 8iC containing approximately 2% BeO as ceramic 12
Using the sintered body, a vacuum vessel for a nuclear fusion reactor with the following metallurgical joint structure of ceramic tiles and metal substrate was fabricated.

The SiC sintered body is a tile-shaped plate measuring 50 m x 50 cm x 10 pieces. The hollow metal member 16 has a bottom part 36 manufactured by machining stainless steel, and the dimensions of the bottom part 36 are the same as those of ceramics, 50 mg x 50 mm, and the thickness is 1 mm.
It's the eyebrows. The outer diameter of the ring portion of the hollow metal member 16 is 45 m.
, the inner diameter is 43 mm, and the height is 4 mm. The intermediate body 14 is a composite material of carbon fiber and copper, and the volume of the carbon fiber is 35.
A composite material with a thickness of 1 mm and a material with a carbon fiber volume of 45 mm and a thickness of 1 wR were laminated at high temperature to form a composite material with a thickness of 2 layers. The thermal expansion coefficient of the former is 10 x 10-
'/C, the latter being 6 x 10-'/l:''.

In addition, the thermal conductivity is approximately 0.5Ca in the stacked state.
t/crIK・s-C. The large metal frame 20 has 5
Using SUS 316 of 00+uX500mX8wR,
The diameter of the side where the hollow metal member 16 is inserted is 45.
100 stepped holes with a length of 2 m and a diameter of 37= on the side facing the metal plate 24 were bored.

SiC sintered body (ceramics 12) and hollow metal member 16
The bonding process is as shown in FIG.
4 and between the intermediate body 14 and the hollow metal member 16, each of which contains 40 wt% manganese and the balance copper.
5 g/d in an argon atmosphere through a 0 Am brazing filler metal.
The test was carried out by heating to 880C by high frequency heating while pressurizing the sample, holding it for about 1 second, and then cooling naturally.

Next, 100 other ends of the hollow metal members 16 to which the tile-shaped SIC sintered bodies have been metallurgically joined by the above method are inserted into the holes of the large metal base 20, and A metallurgical joint 22y&: was formed by an electron beam 38. At this time, the large metal base 20 was fixed and rotated into a circular shape by the electron beam 38't-magnetic field to join. Further, the irradiation position of the electron beam 38 was adjusted so that only the tip of the hooked hollow metal member 16 was locally melted and joined to the large metal base 20. Thereafter, as shown in FIG. 1, a metal plate 24 made of 5US304 and having a thickness of 3 mm and having a convex portion 26 was fixed to the large metal frame 20 with bolts. A vacuum vessel for a nuclear fusion device was manufactured by manufacturing 100 large metal bodies of 500cm x 500cm with ceramic tiles laminated as described above. In order to examine the thermal damage of the vacuum vessel obtained by the above method, plasma heat of d500 W/crIi was applied to the ceramic surface at 1
Irradiation was performed 1000 times with a period of 00 seconds. In this case,
811 minutes of water was flowed through the coolant channel 28. As a result of this test, the surface temperature of the SiC sintered body was about 600C and the temperature of the joint was about 3000C, but no destruction of the ceramics or the joint was observed.

〔Effect of the invention〕

When conventional large metal substrates and ceramics are mechanically joined by shrink fitting, the limit of plasma heat applied is 80°C.
Although it was about W/crA, it was able to be significantly improved by configuring it as in this example. Also,
Previously, it was only possible to make ceramics with a size of about 10W
Even if the ceramic is larger than the loI angle, a plurality of ceramics can be attached to a large metal frame.

As described above, according to the present invention, it is possible to prevent thermal stress fracture of ceramics and joints when joined to a large metal frame, and to obtain a long-life, highly reliable vacuum vessel for a fusion device. did it.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of a vacuum vessel for a nuclear fusion device having a ceramic tile structure according to the present invention, and shows
-IN; FIG. 2 is a cutaway perspective view of the bonded portion of the ceramic according to the present invention; FIG. 3 is a perspective view showing the state of bonding between the ceramic and the hollow metal member; 3 is a sectional view taken along line IV-■, FIG. 5 is a sectional view showing another example of the hollow metal member, and FIG. 6 is a hollow metal member bonded with ceramics inserted into a joining hole of a large metal frame. FIG. 7 is a cross-sectional view showing a method of joining a hollow metal member and a large metal frame, and FIG. 8 is a cross-sectional view showing an embodiment of the vacuum vessel for a nuclear fusion device according to the present invention. be. 10...Furnace wall body, 12...Ceramics, 14...
- Intermediate body, 16... Hollow metal member, 20... Large metal base, 24... Metal plate, 28... Coolant channel, 3
o...Hollow part.

Claims (1)

[Claims] 1. In a vacuum vessel for encapsulating plasma particles in a nuclear fusion device, the inner furnace wall of the vacuum vessel exposed to plasma particles is forcibly cooled with a large number of divided heat-resistant ceramic tiles. It has a laminated structure in which a large metal base is metallurgically joined via a hollow metal member, and a predetermined gap is formed between adjacent ceramic tiles. Vacuum vessel for nuclear fusion equipment. 2. The large metal base body has a coolant flow path, and the coolant flow path communicates with the hollow part of the hollow metal member, as set forth in claim 1. Vacuum vessel for nuclear fusion equipment. 3. The nuclear fusion according to claim 1, wherein the hollow metal member and the ceramic tile are joined via an intermediate having a coefficient of thermal expansion between the two. Vacuum container for equipment. 4. Claim 3, wherein the intermediate body is an intermediate body whose coefficient of thermal expansion increases continuously or stepwise from the ceramic side to the hollow metal member side.
A vacuum vessel for a nuclear fusion device as described in . 5. The vacuum vessel for a nuclear fusion device according to claim 3, wherein the intermediate body is made of a composite material in which 30 to 60% by volume of carbon fibers are embedded in copper. 6. After joining one end of the hollow metal member and the ceramic tile via an intermediate, inserting the other end of the hollow metal member into a bonding hole formed in a large metal base provided with a coolant flow path, A method for manufacturing a vacuum vessel for a nuclear fusion device, characterized by joining the large metal base and the hollow metal member.