JP3358932B2 - Vacuum container for 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 vacuum vessel for a nuclear fusion device (a fusion reactor and a nuclear fusion experiment device).

[0002]

2. Description of the Related Art A vacuum vessel of a nuclear fusion apparatus which has a multi-wall structure of a vacuum vessel body surrounding a plasma for generating a nuclear fusion reaction, and which is filled with a shielding material between the walls of the vacuum vessel body to secure shielding performance, Conventionally known.

[0003]

In a nuclear fusion device (fusion reactor and nuclear fusion experimental device) that generates a nuclear fusion reaction using deuterium or the like as a fuel, a vacuum vessel body surrounding a plasma by neutrons generated by the nuclear fusion reaction, Structures inside and outside the vacuum vessel body are activated. When the dose of radiation generated by the nuclear fusion reaction and the radiation from each of the above-mentioned activated devices is high, the operation of the coil can be stabilized by increasing the heat generated in the coil that creates the magnetic field necessary to generate and maintain the plasma. And it may be impossible to maintain the plasma.

[0004] When the activation level is high, it becomes impossible for workers to access the equipment when repairing or remodeling the above equipment or performing processing during decommissioning, etc., and remote maintenance is required. There are problems such as unavoidable. In order to solve these problems, measures to install a structure with excellent shielding performance, such as tungsten, on the surface of the vacuum vessel main body and structures inside and outside the vacuum vessel main body, and the vacuum vessel main body and the vacuum vessel Measures for fabricating structures inside and outside the body have been proposed.

[0005] In any case, however, in order to suppress the nuclear heat generated in the coil and to lower the activation level to a level that allows an operator to approach in a limited space, a multi-structure vacuum is required. radiation shielding material and boron water made of metal between the walls of the container body or filled with (shielding water) and, B ₄ C
It is necessary to load a powder or a compact (such as a sphere, pellet, or plate) into shielding water (in this case, pure water can be used) as a thermal neutron absorber. is there.

In the case of using boron water, a processing system for processing the boron water is required for a heating / cooling system, a circulation system, and the like of the vacuum vessel body. On the other hand, when a thermal neutron absorber is added as powder or a compact in shielding water, lack of shielding performance due to non-uniform loading and complicated structure are caused.
Problems have arisen regarding the feasibility and reliability of the furnace body system.

As described above, in the conventional vacuum vessel of a nuclear fusion apparatus, in a limited space, nuclear heat generated in a coil is reduced, and radiation of the vacuum vessel body and structures inside and outside the vacuum vessel body is reduced. In order to reduce the level of chemical conversion, the following two points had to be satisfied. That is, a structure with excellent shielding performance such as tungsten is installed on the surface of the vacuum vessel body and the structure inside and outside the vacuum vessel body, or the vacuum vessel body and the structure inside and outside the vacuum vessel body are manufactured using a low activation material. I do. A radiation shielding material made of metal is arranged between the walls of the vacuum vessel body having a multi-wall structure, and a high-concentration ¹⁰ B (boron 1)
0) -containing boron water (need to be maintained at a high temperature to prevent boron precipitation) is circulated between the walls of the vacuum vessel main body as shielding water, or added to metal shielding material and shielding water (pure water). , B ₄ C, etc. or a compact (spherical, pellet-like, plate-like compact, etc.) is loaded between multiple walls as a thermal neutron absorber. Needed.

Therefore, when using boron water, a heating / cooling system, a circulation system, etc. of the vacuum vessel main body require a processing system facility for processing high-temperature and high-concentration boron water, or a reaction between boron and neutrons. The tritium generated by the system is carried out of the main body of the vacuum vessel through these systems, and there are problems with respect to the feasibility and reliability of the furnace main body system.

On the other hand, when a powder or a compact such as B ₄ C is loaded between multiple walls as a thermal neutron absorbing material, lack of shielding performance due to non-uniform loading (reduction of shielding performance) or structure Problems such as shielding performance and structure. The present invention has been made in view of the above problems, and its object is to reduce the radiation dose rate inside and outside the vacuum vessel body, improve the safety and reliability of the vacuum vessel body, and improve the furnace body system. It is an object of the present invention to provide a vacuum vessel of a nuclear fusion device which can simplify the structure of the vacuum vessel main body, improve the shielding performance, and improve the safety of the furnace main body system.

[0010]

In order to achieve the above object, the present invention provides a vacuum vessel body surrounding a plasma for generating a nuclear fusion reaction having a multi-wall structure, and a shielding material is provided between the walls of the vacuum vessel body. In a vacuum vessel of a nuclear fusion device which is filled to secure shielding performance, at least one of the vacuum vessel body and the shielding material is made of a boron-containing metal.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a vacuum vessel of a nuclear fusion device of the present invention will be described with reference to FIGS. FIG.
Is a schematic diagram of a nuclear fusion device, and FIG. 2 is a structural conceptual diagram of a vacuum vessel (a double-walled vacuum vessel) showing an enlarged part A of FIG. 1 is a plasma, and the plasma 1 is
The confinement and shape control are performed by the coil 3 and other magnetic field generating coils (not shown).

1 and 2, reference numeral 2 denotes a vacuum vessel main body, 2a denotes an inner wall of the vacuum vessel main body 2, 2b denotes an outer wall of the vacuum vessel main body 2, and structures inside and outside the vacuum vessel main body 2 and the vacuum vessel 2 (not shown). ) Receives radiation from the nuclear fusion reaction and radiation from structures inside and outside the activated vacuum vessel body 2. For this reason, it becomes impossible for workers to access the equipment activated at the time of repair or the like, or nuclear heat generated in the coil 3 increases, which hinders stable operation of the coil 3. , The plasma 1 cannot be maintained.

As shown in FIG. 2, a material having a high shielding effect, such as tungsten, is disposed as a structure 4 on the surface of the vacuum vessel main body 2 in order to allow an operator to access the inside and outside of the vacuum vessel main body 2. In order to shield the coil 3 from radiation, the wall of the vacuum vessel body 2 having a multi-wall structure has been proposed. Metal shielding material (mainly γ
It is necessary to load a metal shielding material 5 that absorbs rays and fast neutrons, shielding water (shielding water that mainly absorbs thermal neutrons) 6, and possibly a thermal neutron absorbing material (not shown). .

In order to secure a predetermined shielding performance and reduce nuclear heat generated in the coil 3 in a limited space,
The use of boron water as the shielding water 6 is considered. However, in order to enhance the thermal neutron absorption effect, boron water containing a high concentration of ¹⁰ B (boron 10) (it is necessary to maintain a high temperature to prevent boron precipitation) is filled between the walls of the vacuum vessel main body 2. It is necessary to heat the vacuum vessel body 2
A cooling system, a circulation system, etc., require processing system equipment for treating high-temperature and high-concentration boron water, and tritium generated by a reaction between boron and neutrons is carried out of the vacuum vessel body 2 through these systems. However, problems have arisen regarding the feasibility of the furnace body system.

On the other hand, a powder or a compact such as B ₄ C is used as a thermal neutron absorbing material (not shown) as a metal shielding material 5 and shielding water 6.
(In this case, pure water can be used.) In addition, when loading between multiple walls, there is a problem regarding shielding performance and structure such as lack of shielding performance due to uneven loading and complicated structure. Has occurred. However, in the vacuum vessel of the fusion device of the present invention, at least one of the vacuum vessel main body 2 and the shielding member 5 is made of a boron-containing metal, and pure water can be used for the shielding water 6, so that high-concentration boron water can be used. All the disadvantages associated with the use of the furnace are eliminated, a uniform shielding effect is expected, and the structure is simplified, so that a furnace body system with high safety and reliability can be obtained.

[0016]

The vacuum vessel of the nuclear fusion device of the present invention is constructed as described above, and can achieve the following effects. (1) Since boron contained in the vacuum vessel main body 2 and the shielding material 5 promotes absorption of thermal neutrons, radiation generated by a reaction between the constituent materials of the vacuum vessel main body 2 and the shielding material 5 and the thermal neutrons. The amount of radiation can be reduced, the activation level of these devices can be reduced, and the radiation dose rate inside and outside the vacuum vessel main body 2 can be reduced. (2) When high-concentration boron water is used for the shielding water 6, it is necessary to maintain the shielding water 6 at a high temperature in order to prevent the precipitation of boron. -Although a processing system for processing high-concentration boron water is required, according to the vacuum vessel of the present invention, since pure water can be used as shielding water, there is no need for a processing system for processing high-temperature, high-concentration boron water. And the furnace body system can be simplified. (3) Since it is not necessary to use high-concentration boron water as the shielding water 6, the constituent materials of the vacuum vessel main body 2 and the shielding material 5 can be less corroded, and the safety and reliability of the vacuum vessel main body 2 can be improved. . (4) In addition to the shielding material 5 and the shielding water 6, it is not necessary to load a powder or a compact such as B ₄ C between multiple walls, so that the structure of the vacuum vessel main body 2 can be simplified, and Since there is no non-uniformity of the existence distribution in the multi-wall such as a molded body, the shielding performance can be improved. (5) Tritium is generated by a nuclear reaction between neutrons and boron. If boron water is used as shielding water, the generated tritium is taken out of the vacuum vessel body through a heating / cooling system to ensure safety. Although not desirable in terms of point, according to the vacuum vessel of the present invention, when boron is added to the metal, the generated tritium stays in the metal,
Outflow to the outside of the vacuum vessel main body 2 can be prevented as much as possible, and the safety of the furnace main body system can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a nuclear fusion device of the present invention.

FIG. 2 is a structural conceptual diagram of one embodiment of a vacuum vessel showing an enlarged view of a portion A in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma 2 Vacuum container main body 2a Inner wall of vacuum container main body 2b Outer wall of vacuum container main body 3 Coil 4 Shielding structure 5 Shielding material 6 Shielded water

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naoyuki Miya 1 at 801 Mukaiyama, Naka-machi, Naka-machi, Naka-gun, Ibaraki Pref. Inside the Japan Atomic Energy Research Institute Naka Research Institute (72) Inventor Yu Suzuki 2-5-1 Marunouchi, Chiyoda-ku, Tokyo No. Mitsubishi Heavy Industries, Ltd. (56) References JP-A-6-249980 (JP, A) JP-A-62-89840 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G21B 1/00 G21C 19/06

Claims (1)

(57) [Claims] 1. A vacuum vessel for a nuclear fusion device, wherein a vacuum vessel body surrounding a plasma generating a nuclear fusion reaction has a multi-wall structure, and a shielding material is arranged between the walls of the vacuum vessel body to ensure shielding performance. The shielding material is made of a boron-containing metal.
A vacuum vessel for a nuclear fusion device characterized by comprising shielded water made of pure water between walls .