JPH0120398B2 - - Google Patents

Description

[Detailed Description of the Invention] At nuclear fusion experimental facilities, neutrons with energy several times higher than that of nuclear fission reactions are emitted, activating surrounding shields and making it difficult for humans to approach them even after the experiment is complete. . In order to shield the high-energy neutrons in the building, concrete with a thickness of 2 meters or more is required, but the concrete itself becomes radioactive to a high level, and after the experiment, radiation is emitted from the concrete structure and the experiment is interrupted. Work directly performed by humans, such as maintenance, inspection, and modification of equipment, becomes impossible.

Additionally, tritium, a hydrogen isotope generated during experiments, is a light gas with small molecules, so even if the outside of the device is tightly sealed,
It is predicted that it will be extremely difficult to contain the leaked material in the building, considering the hair cracks in the concrete and the sealing conditions at the entrances and exits.

The present invention was proposed for the purpose of minimizing the activation of the shield in such a nuclear fusion experimental facility building and effectively confining thorium. The experimental facility was surrounded in all directions by beams and pillars made of low-activation aluminum alloy, and the alloy water tank filled with shielding pure water was supported, and the water tank was equipped with a purification and cooling system. This relates to a nuclear fusion experimental facility building, characterized in that the building is connected to the shielding pure water circulation device installed therein.

In the experimental plan, we did not conduct an experiment involving tritium from the beginning, and since neutron shielding and tritium confinement would be required in the second stage, we did not set strict conditions from the beginning and added the necessary components later when necessary. In the first stage, the structure will be designed to support its own weight and equipment load and satisfy the load resistance during earthquakes, and in the second stage, it will be constructed to support beams and columns made of low-activation aluminum alloy that surround the experimental facility. The material surrounds the experimental facility in all directions and supports a water tank filled with shielding pure water.

According to the present invention, the experimental facility is surrounded in all directions by a barrier composed of a water tank filled with pure water for shielding, so activation of the shield by neutrons is prevented, and the barrier By maintaining a negative pressure between the inner chambers during the experiment, and applying pressure from the outside of the sealing material at the water tank joint to actively flow clean air into the barrier and prevent the air inside the varimer from flowing out, Tritium can be effectively confined.

In addition, in the present invention, the water tank is connected to a shielding pure water circulation device in a tank equipped with a purification cooling device, so that radioactive substances and decomposed gas due to radiation are purified by the device. After treatment, the pure water in the tank can be reused.

The present invention will be described below with reference to the illustrated embodiments.

In the first stage of the experiment, in which the fusion experimental facility B is located in Building A and is not exposed to radiation, Building A is constructed with the functions of a general building.

In the second stage experiment involving the generation of neutrons, the walls, ceiling, and floor facing Experimental Facility B undergo activation to a certain depth below the surface.

In order to prevent this, a water tank 3 made of low activation aluminum alloy is placed on the outside of the pillars 1 and beams 2 made of low activation aluminum alloy arranged around the outer periphery of experimental facility B, and on the floor, surrounding all directions of experimental facility B. The tank is filled with shielding pure water 4, and the shielding pure water is circulated through the pure water purification and cooling system 5 for nuclear facilities installed outside building A. The water supply pipe 6 and water return pipe 7 in the device are connected to the water tank 3, and the pure water in the water tank 3 is circulated to remove radioactive impurities in the pure water, treat the decomposed gas due to radiation, and re-inject the water into the water tank 3. This is to be returned to tank 3.
By repeating these operations, radioactive materials can be disposed of in a fixed location in the building, greatly reducing the amount of human bodies that come close to the building after the experiment and the amount of radioactive material handled during building demolition. It is something that forces you to do something.

Furthermore, since the experiment requires the use of tritium, which is an isotope of hydrogen, the possibility of leakage from the experimental equipment B must be taken into consideration.

Since the water tanks 3 are installed continuously without gaps and are filled with pure water 4, tritium can be sealed with this pure water.

Next, as shown in FIG. 3, at the joints between the water tanks 3, seal seats 9 having a trapezoidal cross section are provided at the corners of the joints on the outside of the water tanks 3, and a hollow rubber sealing material 10 is placed between the seats 9. They are fitted, sealed with a presser foot 11, and a seal material 12 is fastened with bolts 13 between each seat 9, and a trapezoidal pipe-shaped space 14 is formed by the seal seat 9 and the presser foot 11. do. Then, a pressure P ₁ is applied to the hollow 10a of the hollow rubber sealing material 10,
The sealing material 10 is expanded and brought into close contact with the catch seat 9 and the presser foot 11. Furthermore, clean compressed air is injected into the space 14. The air pressure P ₂ at this time is the pressure P ₁
To make it larger, add the hollow rubber sealing material 10 to the water tank 3.
It is crimped to the side, and if there is an airflow, it always flows towards the inside of the barrier, which, together with the negative pressure inside the barrier, prevents tritium from leaking to the outside.

FIG. 2 shows details of the water tank 3, and the shaded area is one unit of the water tank 3. A stepped key 15 is provided at the joint between the water tanks to prevent neutrons from penetrating, and polyethylene is used inside the water tank 3 to circulate the pure water 4 without stagnation and to improve the neutron shielding ability. A partition material 16 is provided. This partition member 16 is provided with openings 17 of appropriate sizes at appropriate positions in order to constitute a waterway that allows water to flow evenly and without stagnation. Further, in order to avoid penetration of neutron flow, the reinforcing ribs 18 of the water tank 3 are arranged so as not to connect the inside and outside of the barrier. Adjacent water tanks 3 are joined by tightening bolts 20 inserted through tightening flanges 19.

Note that 21 in the figure is a traveling crane for assembling the water tank and the experimental facility.

The pure water 4 is sent to the water tank 3 from the pure water purification cooling device 5 through the water pipe 6, circulates in the water tank without stagnation, and is sent to the pure water purification cooling device 5 through the return pipe 7. return.

When installing experimental facility B, since facility B is a heavy object, it will be fixed to the lower concrete structure with a strong stainless steel skirt 22, but the surrounding area will be shielded with circulating pure water 4. Ru. Even after the experiment, the skirt 22 will still be radioactive, so the water shield on the floor will remain in place and the circulating water will continue to be purified to protect against radiation.

The water tank 3 is installed during the second stage of the experiment, so after the first stage experiment is completed, the column 1 and the beam 2 are assembled, and the water tank 3 is installed on the pillar 1 and the beam 2 using the ceiling crane 21. will be installed.

In the above-mentioned embodiment, the shielding pure water tank is constructed by combining small water tanks for convenience of assembly, but it may be constructed as a whole integrated on-site assembly. In this case, the number of joints in the water tank is reduced or eliminated, and the tritium sealing effect is further improved.

In addition, boron-containing pure water is considered to be more effective for neutron shielding, so boron-containing pure water will be used as necessary, and the necessary purification and cooling equipment will be added.

Although the present invention has been described above with reference to embodiments, the present invention is, of course, not limited to such embodiments, and can be modified in various ways without departing from the spirit of the present invention. .

[Brief explanation of drawings]

FIG. 1 is a general sectional view showing one embodiment of a fusion experimental facility building, FIG. 2 is a detailed view of the portion shown in FIG. 1, and FIG. 3 is a detailed view of the portion shown in FIG. 2. 1... Column, 2... Beam, 3... Water tank, 5... Pure water purification cooling device, 6... Water pipe, 7... Water return pipe.

Claims (1)

[Claims] 1. A water tank made of the alloy that surrounds the experimental facility in all directions and is filled with pure water for shielding, on beams and pillars made of low activation aluminum alloy that are placed around the outer periphery of the fusion experimental facility. What is claimed is: 1. A nuclear fusion experimental facility building, characterized in that the water tank is connected to the shielding pure water circulation system in which a purification cooling system is interposed.