JPH0820531B2 - Vacuum container for nuclear fusion device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torus type vacuum container for a nuclear fusion device (including a nuclear fusion reactor in the present specification) which is required to have radiation shielding performance.

[0002]

2. Description of the Related Art Generally, a torus-type vacuum vessel of a nuclear fusion device that accompanies the generation of neutrons has a vacuum boundary formed for confining the plasma, and is durable against external load during operation or during plasma disruption. Also, it is necessary to have radiation shielding performance.

Further, in the vacuum container structure, from the viewpoint of penetration of the magnetic field at the time of starting the plasma, it is necessary to secure a toroidal resistance in the toroidal direction of several tens of μΩ or more.

In order to satisfy these conditions, the vacuum container of the conventional fusion device has a concentrated resistance type in which a concentrated resistance portion is provided in the toroidal direction, or a shield is electrically and structurally separated to function. The uniform resistance type, which is independent and made of a structural material such as a thin plate, has been adopted.

6 to 9 conceptually show the structure of a concentrated resistance type vacuum container. As shown in the figure, this vacuum container 1 is composed of a metallic shield 2 having a plate thickness that satisfies a predetermined shielding performance, and a plurality of lumped resistors 3 and electrical insulation are provided in order to secure a circular resistance value in the toroidal direction. The portion 4 is arranged at an appropriate position in the toroidal direction of the shield 2.

At the time of plasma disruption, Joule heat is generated in the lumped resistor 3 by the eddy current induced in the vacuum container 1. Therefore, the lumped resistor 3 is required to have a heat capacity capable of allowing its heat generation, and at the same time, to have strength and a support mechanism capable of withstanding the electromagnetic force generated. Therefore, the actual concentrated resistance type vacuum container 1 had an extremely complicated structure as shown in FIG.

11 to 14 conceptually show the structure of a uniform resistance type vacuum container. The uniform resistance type vacuum container 5 is mainly composed of a vacuum container wall 6 and a shield 7 provided therein. Since the shield 7 is electrically and structurally separated by the insulator 8 in the toroidal direction, the vacuum container wall 6 is required to have a structural strength and a circumferential resistance value other than the shielding performance. Therefore, as shown in FIG. 14, for example, the vacuum container wall 6 is configured by a double wall of thin plates 9 and 10 to secure a circumferential resistance value in the toroidal direction without providing a concentrated resistance portion. Structural strength is maintained by arranging the structural material 11 between 9 and 10.

However, since the vacuum vessel wall 6 and the shield 7 need to support each other, some support mechanism 12 is required. The support mechanism 12 has a structure capable of supporting an electromagnetic force generated during plasma disruption, and at the same time, contradictory conditions of absorbing a difference in thermal expansion between the vacuum container wall 6 and the shield 7 and ensuring electrical insulation. Must be satisfied. Therefore, the uniform resistance type vacuum container 5
In this case, especially, the connection structure between the vacuum container wall 6 and the shield 7 must be reliable and realistic, and a high level of technology was required. FIG. 15 shows an example of the structure of an actual uniform resistance type vacuum container.

[0009]

By the way, with the recent progress of plasma technology, it has become possible to allow the circumferential resistance of the toroidal direction required for a vacuum container up to about several μΩ. However, in a vacuum container of a nuclear fusion device using dual hydrogen and tritium as fuel, for example, if a vacuum container wall is made of stainless steel and water, a radiation shield thickness of about 40 to 100 cm is required, while Effective thickness is 10 to 1
If it is not suppressed to 5 cm, it is difficult to set the toroidal resistance in the toroidal direction to about several μΩ without providing the concentrated resistance portion, and the core structure is inevitably complicated.

Further, it has been pointed out as an engineering problem that the reliability of vacuum maintenance and structural strength is deteriorated due to the complicated core structure.

Therefore, an object of the present invention is to provide a simple vacuum container in which both the circumferential resistance value in the toroidal direction and the required radiation shielding thickness are satisfied together with the structural strength.

[0012]

In order to achieve the above object, the torus type vacuum container of the fusion device according to the present invention comprises:
A vacuum container wall which has a predetermined toroidal circumferential resistance value and has at least a double plate structure in which a constant interval is provided between the inner and outer plates, and a large number in the toroidal direction and the poloidal direction in the vacuum container wall. A plurality of shelves arranged in the toroidal direction and the poloidal direction between the plates of the vacuum container wall so as to form a chamber of the vacuum container wall, and the plates of the vacuum container wall and the shelves arranged in each chamber. And a shield electrically insulated from the plate.

[0013]

According to the above structure, the shield can be integrated into the vacuum vessel wall while being electrically separated, and the toroidal resistance in the toroidal direction is about several μΩ, which reflects the recent progress of plasma startup technology. At the same time, it is possible to satisfy the requirements for shielding performance. Further, since a large number of shelves are attached between the plates of the vacuum vessel wall, sufficient structural strength can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

1 and 2 show an embodiment of a vacuum container of a nuclear fusion device according to the present invention. As shown, the vacuum container 20 has a torus shape (annular shape),
The inside is hollow. The vacuum container wall 21 of the vacuum container 20 has a double plate structure including an outer plate 22 having a substantially vertical vertical cross section and an inner plate 23 having a substantially vertical vertical cross section disposed inside the outer plate 22 at a constant interval. Has become. Between the outer plate 22 and the inner plate 23, in order to secure the structural strength of the vacuum container 20, a large number of shelf plates 24 are arranged in the toroidal direction and the poloidal direction. The outer plate 22 and the inner plate 23 of the
Are formed in the toroidal direction and the poloidal direction. As shown in FIG. 3, a shield 26 is arranged in each chamber 25 to ensure neutron shielding performance.

As shown in FIGS. 4 and 5, the shield 26 is made up of a plurality of shield plates 27 which are unitized by a fixing rod 29 and a nut 30 while adjusting the spacing by a spacer 28. Since neutrons generated in the nuclear fusion reaction have high energy, the shield plate 27 needs to be made of a metal (for example, stainless steel) made of an element having a large atomic number. Further, the space between the shield plates 27 also serves as a flow path for cooling water of the vacuum container 20, and by filling the cooling water therewith, a predetermined shielding performance can be obtained. The cooling water is the outer plate 22 of the vacuum container.
Shelving board 2 is put in and taken out from a header (not shown) provided in
It circulates in the vacuum container 20 through the flow path hole (not shown) provided in 4. Each plate 22, 23 surrounding the cooling water,
Since a large potential difference does not occur between 24 and 27, if the cooling water is basically water quality controlled to prevent corrosion of the structural material, it serves as an electrical passage and affects the resistance value around the toroidal direction. Never give.

An insulating material such as a ceramic coating is applied to a contact portion of each shield 26 with the outer plate 22, the inner plate 23 and the shelf plate 24 so that the shield 26 and each plate 22, 23, 24 are contacted with each other. Is electrically isolated. As a result, the circumferential resistance value of the vacuum container 20 in the toroidal direction is secured.

In the above embodiment, the shield 26 is composed of a plurality of unitized shield plates 27. However, an independent shield plate having an insulating material on its surface is used as a shield condition without being unitized. It is also possible to dispose them in each chamber 25 at intervals so as to satisfy the above condition.

The shield may have a structure in which the surfaces of a plurality of metal spheres having a shielding function are subjected to an insulation treatment and the metal spheres are enclosed in a chamber.

Further, although the vacuum container 20 according to the above-mentioned embodiment has a double structure of the outer plate 22 and the inner plate 23, it may have three or more layers in order to increase the structural strength. In the case of triple structure,
The shield will be appropriately disposed between the intermediate plate and the outer plate, between the intermediate plate and the inner plate, or both.

[0021]

As can be understood from the above, the vacuum container of the fusion device according to the present invention basically has a uniform resistance type structure. Therefore, the circumferential resistance value in the toroidal direction can be set to about several μΩ. Further, since the shield is arranged in a chamber formed in the container wall of the vacuum container in an electrically separated state, it is possible to secure a desired shielding performance without impairing the circumferential resistance value in the toroidal direction. it can.

Further, this vacuum container is of uniform resistance type,
And since it has a simple shelf board structure, a simple vacuum container structure is established compared to the conventional one, and it is possible to partially adjust by adding a shelf board as needed in terms of strength,
It also has sufficient flexibility in structural design.

Furthermore, since the shield need only be arranged in the chamber on the wall of the vacuum container and the support mechanism for the shield is not required, the reactor core structure can be simplified. This simplification of the reactor core structure facilitates manufacturing and assembly, reduces costs, and improves reliability in maintaining vacuum and structural strength.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view partially showing a structural concept of a vacuum container of a nuclear fusion device according to the present invention.

FIG. 2 is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is an enlarged view of part B in FIG.

FIG. 4 is a perspective view showing an embodiment of a shield used in the vacuum container according to the present invention.

FIG. 5 is an enlarged sectional view of a portion C in FIG. 4;

FIG. 6 is a horizontal sectional view partially showing a structural concept of a conventional concentrated resistance type vacuum container.

7 is a cross-sectional view taken along the line DD of FIG.

FIG. 8 is a cross-sectional view taken along the line EE of FIG.

9 is an enlarged view of a portion F in FIG.

FIG. 10 is a cross-sectional view of a portion corresponding to part F of FIG. 6, showing a conventional actual concentrated resistance type vacuum container.

FIG. 11 is a horizontal sectional view partially showing a structural concept of a conventional uniform resistance type vacuum container.

12 is a cross-sectional view taken along the line GG of FIG.

13 is a cross-sectional view taken along the line HH of FIG.

14 is an enlarged view of a portion I of FIG.

FIG. 15 is a cross-sectional view of a portion corresponding to part I of FIG. 11, showing a conventional actual uniform resistance type vacuum container.

[Explanation of symbols]

 20 vacuum container 21 vacuum container wall 22 outer plate 23 inner plate 24 shelf plate 25 chamber 26 shield

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Yasushi Seki, No. 801, Mukayama, Naka-machi, Naka-cho, Naka-gun, Ibaraki Prefecture, Japan Naka Research Laboratory, Japan Atomic Energy Research Institute (72) Yu, Suzuki 2-4 Shiba Park, Minato-ku, Tokyo No. 1 Mitsubishi Harajiki Industry Co., Ltd. (72) Inventor Masao Yamada 2-4-1, Shiba Park, Minato-ku, Tokyo Inside Mitsubishi Harajiko Industry Co., Ltd. (72) Mitsuru Tomita Two Marunouchi, Chiyoda-ku, Tokyo 5th-1th Sanryo Heavy Industries Co., Ltd.

Claims (1)

[Claims] 1. A torus type vacuum container used in a nuclear fusion device, which has a predetermined toroidal circumferential resistance value and at least a double plate structure in which a constant space is provided between the inner and outer plates. A vacuum container wall and a plurality of shelves arranged in the toroidal direction and the poloidal direction between the plates of the vacuum container wall so as to form a number of chambers in the toroidal direction and the poloidal direction in the vacuum container wall. A vacuum container for a nuclear fusion device, comprising: a shield disposed in each chamber and electrically insulated from the plate of the vacuum container wall and the shelf plate.