JPH0126035B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an improvement in a water cooling system of a nuclear fusion device that forms a plasma confinement magnetic field using a conductive coil.

[Background of the invention]

Nuclear fusion devices use magnetic fields to confine plasma inside a vacuum discharge tube. In tokamak type nuclear fusion devices, where the confined plasma is a torus, several coils (poloidal coils) are placed around the discharge tube concentrically with the discharge tube.
A large current is passed through this coil to create a magnetic field concentric with the discharge tube that compresses the plasma, confining the plasma. In order to stabilize the confinement of the plasma, a toroidal coil is provided along the poloidal direction (the direction that goes around the torus cross section) of the donut-shaped discharge tube to apply a balanced magnetic field to the discharge tube. When such a nuclear fusion device becomes larger and the volume of plasma increases, the magnetic field required to confine the plasma must be increased, leading to an increase in the size of each of the coils. Therefore, in order to downsize the coil and obtain a strong magnetic field, toroidal coils, trodal coils, and poloidal coils are being created as superconducting coils using superconducting wires. This is true not only for tokamak type fusion devices but also for magnetic field generating coils in other magnetic field confinement fusion devices such as mirror machines that do not confine plasma in a torus.

This superconducting coil is housed in a heat insulating container, cooled by liquid helium, and kept at an extremely low temperature in order to obtain a superconducting state. Furthermore, in nuclear fusion devices, in order to confine high-temperature plasma within the discharge tube, each device within the heat-insulating container is protected by water cooling. However, if the supply of cooling water stops due to some reason such as a pump failure while the fusion device is operating, and the cooling water remains in the piping,
The water in the pipes loses heat to liquid nitrogen (80K) and liquid helium (4.2K) to maintain the extremely low temperature.
There is a risk of freezing and bursting the pipes.

[Purpose of the invention]

The present invention was made in order to eliminate the drawbacks of the prior art, and the supply of cooling liquid to the cooling liquid flow path pipe provided in parallel with the cryogenic liquid cooling device is stopped during the operation of the cryogenic liquid cooling device. An object of the present invention is to provide a nuclear fusion device that can prevent a cooling liquid flow path pipe from bursting even in such a case.

[Summary of the invention]

The present invention provides a liquid flow path pipe provided in conjunction with a low temperature liquid cooling device for cooling a magnetic field generating coil of a nuclear fusion device. Connect a high-pressure gas source that injects gas into the cooling liquid flow pipe when the supply stops, and inject high pressure gas into the cooling liquid flow pipe when the cooling liquid supply and stop. The structure is such that the cooling liquid accumulated in the cooling liquid can be rapidly discharged to prevent the cooling liquid flow path pipe from bursting.

[Embodiments of the invention]

A preferred embodiment of the nuclear fusion device according to the present invention is as follows:
A detailed explanation will be given according to the attached drawings.

FIG. 1 is an explanatory diagram of an embodiment of a nuclear fusion device according to the present invention. In FIG. 1, a discharge tube 10, which is a vacuum vessel for confining plasma, is formed into a donut shape, and a poloidal coil 12 concentric with the discharge tube 10 is provided around the donut shape. Furthermore, a toroidal coil 14 formed as a superconducting coil is arranged around the poloidal coil 12. A radiant heat shielding plate 16 is provided between the poloidal coil 12 and the toroidal coil 14 to prevent radiant heat from the discharge tube 10, which becomes high in temperature, from reaching the toroidal coil 14. Further, the discharge tube 10, the toroidal coil 14, etc. are housed in a heat insulating container 18 and are isolated from the outside world so that the toroidal coil 14 can be kept at a cryogenic temperature by a cryogenic cooling device (not shown).

The poloidal coil 12 is water-cooled, and is connected to a water supply pipe 20 and a return pipe 22. The water supply pipe 20 and the return pipe 22 are each connected to a water tank 24, and the water supply pipe 20 is provided with a pump 26. Furthermore,
A gas blowing pipe 28 communicating with a high-pressure nitrogen gas source (not shown) is connected to the water supply pipe 20, and nitrogen gas (N ₂ ) is supplied to the water supply pipe 2 as shown by an arrow 30.
It is now possible to blow into 0. In addition, the code|symbol 32 shown in the figure is a gas outflow pipe provided in the water tank 24.

The operation of the embodiment configured as described above is as follows. During normal fusion device operation,
The water supply pipe 20 is shut off by a high temperature nitrogen gas source and a valve (not shown). A pump 2 is connected to the poloidal coil 12 via a water supply pipe 20.
The cooling water in the water tank 24 sucked by 6 is passed through. The cooling water that has cooled the poloidal coil 12 returns to the water tank 24 again through the return pipe 22.
On the other hand, the toroidal coil 14 is cooled to a cryogenic temperature by a cryogenic cooling device (not shown). However, when the supply of cooling water to the poloidal coil 12 is stopped due to a pump failure or the like, the flow of cooling water in the water supply pipe 20 and the return pipe 22 is stopped, and the cooling water remains in each pipe. The cooling water remaining in the water supply pipe 20 and the return pipe 22 is cooled by the cryogenic cooling device that cools the toroidal coil 14, and there is a risk that it will freeze and cause the water supply pipe 20 and the cooling pipe 22 to burst. Therefore, when it is detected by a signal from a flow meter, etc. that the supply of cooling water has been stopped, the gas injection pipe 28 is immediately
A high pressure nitrogen gas such as 0 is blown into the water supply pipe 20. For this reason, the water supply pipe 20 and the return pipe 2
The cooling water in the water tank 24 is swept out into the water tank 24 to prevent the cooling water from freezing in the water supply pipe 20 and the return pipe 22, thereby preventing these pipes from bursting. Note that the nitrogen gas that has entered the water tank 24 together with the cooling water is released into the atmosphere from the gas outlet pipe 32.

FIGS. 2 to 4 are explanatory diagrams of other embodiments of the nuclear fusion device according to the present invention. In the embodiment shown in FIG. 2, high-pressure nitrogen gas can be blown into the water supply pipe 20 that cools the discharge tube 10. The discharge tube 10 is water-cooled like the poloidal coil 12, and if the supply of cooling water to the discharge tube 10 stops for some reason, the water supply pipe 20 and return pipe 22 can be connected by performing the same operation as described above. Prevents bursting due to freezing.

In the embodiment shown in FIG. 3, high pressure nitrogen gas can be blown into the water supply pipe 20 that cools the limiter 34 with water. The limiter 34 is provided within the discharge tube 10 to limit the cross-sectional dimension of the plasma and control the position of the plasma. Fourth
In the illustrated embodiment, high-pressure nitrogen gas can be blown into a water supply pipe 20 that cools an air-core current transformer coil with water. The air-core current transformer coil 36 is for passing a large current through the plasma within the discharge tube 10, and is provided at the center of the donut-shaped discharge tube 10 (doughnut).

In the embodiment shown in FIG. 5, the return pipe 22 is provided with a discharge pipe 40 having a solenoid valve 38.
With such a configuration, it can also be applied to a closed system cooling system without a water tank as shown in FIG. Further, the embodiment shown in FIG. 6 shows an example in which high pressure nitrogen gas can be blown into all supply piping and return piping of each water-cooled device provided in the heat insulating container 18. be.

In addition, although the case where the gas blown into the water supply pipe 20 was nitrogen gas was explained in the said Example, this gas may be any dry gas. Further, in the embodiment described above, a case has been described in which the equipment in the heat insulating container 18 is water-cooled, but the cooling medium for cooling these equipment can also be applied to a case where oil or the like is used. Further, in the above embodiment, the case where the toroidal coil 14 is a superconducting coil has been described, but the present invention can be similarly applied to an apparatus in which the toroidal coil 14 is cooled with liquid nitrogen.

〔Effect of the invention〕

As explained above, according to the present invention, the rupture of the cooling liquid flow path pipe when the cooling liquid is not supplied to the cooling liquid flow path pipe provided in conjunction with the low temperature liquid cooling device during the operation of the low temperature liquid cooling device can be prevented. It can be prevented.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of an embodiment of a nuclear fusion device according to the present invention that cools a poloidal coil with water, Fig. 2 is an explanatory diagram of an embodiment of a nuclear fusion device according to the invention that cools a discharge tube with water, and Fig. 3 is an explanatory diagram of an embodiment of a nuclear fusion device according to the present invention that cools a discharge tube with water. FIG. 4 is an explanatory diagram of an embodiment of the fusion device according to the present invention that water-cools an air-core current transformer coil, and FIG. FIG. 6 is an explanatory diagram of an embodiment of the nuclear fusion device according to the present invention, which is a closed system. FIG. 10...discharge tube, 12...poloidal coil,
14...Toroidal coil, 18...Insulating container,
20... Water supply piping, 22... Return piping, 24...
Water tank, 26...pump, 28...gas blowing piping.

Claims (1)

[Claims] 1. A vacuum vessel that accommodates plasma, a magnetic field generation coil that forms a plasma confinement magnetic field disposed around this vacuum vessel, a low-temperature liquid cooling device that cools this magnetic field generation coil, and the vacuum vessel and the magnetic field generation coil. and a cooling liquid flow path pipe provided in conjunction with the low temperature liquid cooling device that cools the equipment in the heat insulation container, the cooling liquid flow path pipe is configured to contain the A fusion device characterized in that the fusion device is connected to a high-pressure gas source that injects gas into the cooling liquid flow path when the supply of cooling liquid to the cooling liquid flow path is stopped during operation of the low temperature liquid cooling device. .