JPH0786540B2 - Fusion reactor protection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides protection for preventing internal damage due to reaction with inflowing air when air leaks into a vacuum vessel for generating plasma in a fusion reactor. Apparatus and fusion reactor.

[Conventional technology]

In a fusion reactor, a shield for radiation in a vacuum vessel that generates plasma, a blanket for tritium breeding, a first wall installed in a part directly facing the plasma to prevent damage to equipment due to heat flux from the plasma, a diverter Many devices such as boards are installed. In particular, the first wall and the diverter plate have a high temperature of several hundreds of degrees from several hundreds of degrees. At present, graphite, Be, W, and Mo are considered to be the most suitable materials from the viewpoint of reducing radiation loss due to inflow of impurities into plasma. On the other hand, the vacuum vessel of the fusion reactor is provided with a large number of ports such as a cooling water introduction port for equipment inside the vessel, a connection port for equipment for plasma heating / current drive, an instrumentation port, and a vacuum exhaust port.

[Problems to be Solved by the Invention]

For this reason, in the conventional technology, there is a risk that air leaks into these ports and connected devices, and air flows into the vacuum container. If air flows in when the first wall is hot, graphite and oxygen in the air may react and burn,
For this reason, the internal pressure may rise to 1 atm or more, and tritium, which is a radioactive substance, may flow out. IA in this regard
EA Issued Eater Concept Definition 2nd
Volume 349 pages (1989) (ITER Concept Definition Vol.2 P
349 (1989) IAEA Vienna). Even with conventional fusion devices, the same phenomenon is conceivable even if the scale is small. However, in the conventional device, the temperature of the first wall is not so high, the plasma discharge time is about 10 seconds, which is two digits shorter than that of the furnace, and the fact that tritium, which is a radioactive material, is not used, has such an effect. Small, no protective device considered.

An object of the present invention is to prevent air from flowing into the vacuum container when a leak occurs in the vacuum container and a device connected to the vacuum container, and as a result, damage to the first wall, diverter, etc. due to reaction with air. To provide a fusion reactor protection device and a fusion reactor capable of preventing the above.

[Means for Solving the Problems]

In order to achieve the above object, a leak is detected by a vacuum gauge, a quadrupole mass spectrometer (Q mass), or other measuring instrument for measuring the degree of vacuum, and an inert substance such as nitrogen, helium, or argon that does not react with graphite. The liquefied product of (1) is injected into a vacuum container in a short time and vaporized inside to suppress the inflow of air from a leak place to some extent.

Furthermore, in order to prevent the inflow of air itself, the room in which the vacuum container and the equipment connected to it are set is made airtight, and a rare gas such as nitrogen or helium is filled instead of air.

That is, according to the present invention, a vacuum degree measuring device that detects the degree of vacuum of a vacuum container that generates plasma, a storage container for a liquid inert substance, and the storage container and the inside of the vacuum container are connected via a valve. A fusion reactor protection device comprising: a conduit; and a valve controller that receives an output of the vacuum degree measuring device and outputs a signal for opening the valve when the vacuum degree is a predetermined value or less.

Further, the present invention is a peripheral installation device connected to a vacuum container for generating plasma via a port, and a storage chamber having an airtight structure for independently storing the peripheral installation device,
A storage container for an inert substance, which is connected to this storage chamber via a valve, wherein air in the storage chamber is replaced by an inert gas at atmospheric pressure, thereby protecting a fusion reactor. It is a device.

Further, the present invention, a cryostat, a vacuum container provided in the cryostat, a toroidal coil and a poloidal coil provided in the vacuum container, a port for connecting a peripheral installation device and a vacuum container outside the cryostat, a vacuum In a fusion reactor including a first wall and a diverter plate provided on an inner wall of a container, a vacuum degree measuring device for detecting a vacuum degree of a vacuum container, a storage container for a liquid inert substance, and this storage container And a valve communicating with the inside of the vacuum container via a valve, and a valve controller that receives the output of the vacuum degree measuring device and outputs a signal for opening the valve when the vacuum degree is a predetermined value or less. It is a thing.

Further, the present invention, a cryostat, a vacuum container provided in the cryostat, a toroidal coil and a poloidal coil provided in the vacuum container, a port for connecting a peripheral installation device and a vacuum container outside the cryostat, a vacuum In a fusion reactor including a first wall and a diverter plate installed in a container, an airtight storage chamber for independently storing peripheral installation devices connected through the port, and this storage A storage container for an inert substance, which is connected to the chamber via a valve, is provided, and the air in the storage chamber is replaced with an inert gas at atmospheric pressure. In the fusion reactor,
The first wall and the diverter plate are preferably made of graphite, beryllium, tungsten or molybdenum.

[Action]

When a value measured by a vacuum gauge or a vacuum degree measuring device such as a Q-mass exceeds a certain value, it is determined that a leak has occurred, and a signal is output to the outside. In response to this signal, the control circuit sends an opening / closing signal to the solenoid valve or pneumatic valve that shuts off the storage container for the inert material such as liquid nitrogen and helium and the vacuum container, and vacuums the liquid nitrogen and helium. Pour into a container. Thus, if these substances are injected so that the inside of the vacuum container becomes atmospheric pressure earlier than the inflow of air from the leak location, the inflow of air can be suppressed to the minimum.

On the other hand, if the room in which the equipment connected to the container and vacuum container and the ports that connect them are installed is made airtight and the air inside is replaced with noble gases such as nitrogen and helium at atmospheric pressure, a leak will occur. However, since a gas such as nitrogen that does not react with graphite flows in from the leak location instead of air, damage to the graphite can be prevented.

〔Example〕

 An embodiment of the present invention will be described below with reference to FIG.

Figure 1 shows a vertical cross section of the core of a tokamak fusion reactor. In a tokamak-type fusion reactor, a toroidal coil 3 and a poloidal coil 4 each composed of a superconducting coil are installed around a donut-shaped vacuum container 2 that generates a donut-shaped plasma 5. In order to reduce heat intrusion into the superconducting coil, these devices are installed in the cryostat 1 whose inside is evacuated. Inside the vacuum container 2,
Neutrons and γ generated from fusion reaction in plasma
The shield 6 is installed so that the induced radioactivity such as a wire does not leak to the outside. Further, in order to protect the shield and the vacuum container from the plasma heated to an extremely high temperature, the first wall 9 and the diverter plate 10 are installed at the place directly facing the plasma.
These are heated from several hundred degrees to a few hundred degrees in the high temperature part by particles and radiation from plasma. From the first wall and the diverter plate heated to a high temperature, these constituent elements flow into the plasma due to evaporation, sputtering, etc., and become impurities to reduce the temperature of the plasma. Therefore, an element having a low atomic number, which has a small adverse effect on plasma, is used as a material for the first wall and the diverter plate. From this point of view, graphite, Be, W and Mo are currently considered to be the most promising materials.

The vacuum vessel 2 includes a device for heating plasma or driving current, a measuring device for measuring various amounts of plasma, a first device.
Cooling water inlet for cooling the wall 9 and the diverter plate 10,
Many devices such as vacuum pumps are connected. For this purpose, many horizontal ports 7 and vertical ports 11 are provided, and as shown in FIG. 1, they are pulled out to the outside of the cryostat 1. Various devices are connected to these ports 7 and 11,
Since the equipment is installed in the atmosphere, when a crack or a hole occurs in the connected equipment or the connecting portion, the port portion, the observation window, etc., a leak occurs and the atmosphere flows into the vacuum container 2.
When a leak occurs, the vacuum degree of the vacuum container 2 deteriorates, so that the leak degree can be detected by a vacuum degree measuring device 13 such as a vacuum gauge connected to the flange 8 or a quadrupole analyzer (Q mass). When the degree of vacuum or the rate of decrease of the degree of vacuum exceeds a predetermined value, the signal 23 is output to the outside. On the other hand, a storage container 17 for liquefied rare gases such as nitrogen, helium, and argon is a remote control valve 16 such as a solenoid valve or a pneumatic valve.
And attached to the flange 12 via the injection conduit 15,
It is connected to the vacuum container 2. The signal 23 output from the vacuum measuring device 13 is input to the valve control device 14 and outputs a valve opening / closing signal 24 according to the input signal. The valve 16 opens and closes in response to this signal 24. When a leak is detected, the valve opens and the nitrogen and rare gas liquefactions in the storage container 17 are piped.
It is injected into the vacuum container 2 through 15 and is rapidly vaporized to fill the vacuum container 2 with these gases. Since liquefaction is generally extremely low, it evaporates even in small quantities. Storage container for this
A relief valve 18 for the vaporized gas and a replenishment conduit 19 are connected to 17, and a liquefaction is replenished by a pump 20 from a replenishment tank 21. The storage container 17 has a built-in liquid level indicator, and a liquid level signal 25
Is output to the pump control device 22, and when the liquid level falls below a predetermined level, the pump 20 is operated, and the storage tank
Add liquefaction to 17. At this time, if the operating pressure of the relief valve 18 is set to an appropriate value, for example, 10 atm, at the same time as the valve 16 is opened, the liquefaction is injected into the vacuum container 2 through the conduit 15 by the pressure of the vaporized gas of its own. To be done.

Since the volume of the vacuum vessel of the fusion furnace is on the order of 1000 m ³ , liquefaction on the order of 1 m ³ may be injected to bring the vacuum vessel to atmospheric pressure. When the pressure of the vacuum container body exceeds 1 atm, the container itself may be destroyed, or radioactive substances such as tritium existing in the container may be released to the outside.
The ultimate pressure of the injected gas must be about atmospheric pressure. Therefore, the volume of the storage container 17 is set to a value that is necessary and sufficient to bring the vacuum container to about atmospheric pressure when the liquefaction is gasified in the vacuum container. Further, the vacuum measuring device 13 detects that the atmospheric pressure is reached, and the valve control device 14 is operated to operate the valve.
16 should be closed. If not only one port of the conduit 15 but also several ports in the donut circumferential direction can be attached, liquefaction can be injected more rapidly. Further, if the storage containers 17 are not installed one by one but installed in several, the length of the conduit through which the cryogenic liquefaction flows can be shortened, so that the storage container 17 can be injected more effectively.

As described above, since a liquefied substance having a volume 1000 times smaller than that of a gas is injected, the inside of the vacuum container can be brought to atmospheric pressure in a short time after the leak is detected, so that the air inflow from the leak location can be suppressed to a small amount. As a result, there is an effect that damage to the first wall due to a reaction with oxygen in the air can be prevented.

FIG. 2 shows a comparative example. In this comparative example, high-pressure gas is injected instead of the liquefaction. That is, in FIG. 2, the vacuum degree measuring device 13 detects the leak and outputs the output signal.
23 is input to the valve controller 14. In response to the signal, the valve control device 14 outputs an opening / closing signal 24 to the gas valve 27. Gas valve 27
Operates in response to the signal, a valve opens when a leak is detected, and a high-pressure gas is injected into the vacuum container from a high-pressure gas storage container 28 of a rare gas such as nitrogen, helium, or argon through a conduit 15. The volume of the storage container 28 is set to a necessary and sufficient amount to bring the vacuum container to the atmospheric pressure, and the internal pressure of the vacuum container is measured by the vacuum degree measuring device 13 as shown in FIG. The gas valve 27 via the valve control device 14.
To close. In this comparative example, the injection rate becomes smaller than that in the case of using a liquefied material.

FIG. 3 shows another embodiment of this embodiment. FIG. 3 is a side view of the periphery of the core of the fusion reactor, conceptually showing its structure. The equipment inside the cryostat 1 is arranged in axial symmetry, so half of it is shown for simplicity. The vacuum container 2 is provided with a large number of vertical ports 11, horizontal ports 7 and diagonal ports 29, and a vacuum exhaust device 30 and a plasma heating device 32 are connected to the vacuum container by opening a conduit 31. A power supply 34 is connected to the heating device 32 through a power line 33.
Other than these, the same equipment is connected to the vacuum vessel and arranged around the core. The room in which these devices and conduits are arranged is an independent room for each type, that is, the furnace room 40 in which the furnace body is installed, and the exhaust device room 3 in which the vacuum exhaust device is installed.
8. There are many heating device chambers 39 in which the heating devices 32 are installed, pipe chambers 41 through which conduits pass, and they are arranged around the furnace chamber. The room in which the conduits and equipment that are connected to these vacuum vessels in a vacuum are installed has an airtight structure, and the air inside is replaced with noble gases such as nitrogen, helium, and argon at atmospheric pressure. Also, through these conduits 35 and pressure reducing valve 36,
The gas container 37 is connected so that the room pressure is always maintained at atmospheric pressure. By doing so, even if a leak occurs in these conduits, devices or ports, their connecting portions, etc., air does not flow in, but gas such as nitrogen is injected. Since the volume of the vacuum container is 1000 m ³ or more, the pressure in the room drops in a small room, but the conduit 35 causes the external gas container 37
Since the gas is replenished from the inside, it does not fall below the atmospheric pressure, and the room is not damaged by the pressure difference. As described above, according to the present embodiment, even if a leak occurs in the conduits and devices vacuum-connected to the vacuum container, their installation space is filled with a rare gas such as nitrogen or helium. Since air does not flow in and a reaction with high temperature graphite does not occur, it has an effect of not destroying them.

〔The invention's effect〕

According to the present invention, there are cracks and holes in the conduits and equipment connected to the vacuum vessel of the fusion reactor and leaks occur, and even if the atmosphere enters the vacuum vessel, nitrogen, helium, argon, etc. Since the vacuum container can be brought to atmospheric pressure in a short time before inflowing air with an inert substance and the air inflow amount can be suppressed to a small amount, the reaction between oxygen in the air and high temperature graphite which is a material for the first wall and the like is suppressed. In addition, there is an effect that the destruction of graphite can be prevented. That is, since a liquefied substance of a rare gas such as nitrogen or helium is injected, a larger amount of an inert substance can be injected in a shorter time, so that the inflow of air can be suppressed to a smaller amount.

Furthermore, since it is replaced by noble gases such as nitrogen, helium, and argon at atmospheric pressure where the conduits and equipment connected to the vacuum container are installed, air can flow in even if a leak occurs in these equipment. Since it does not exist, the reaction between oxygen in the air and high temperature graphite does not occur at all, and there is an effect that the destruction of the first wall and the like can be prevented.

[Brief description of drawings]

FIG. 1 is an embodiment of the present invention, a vertical sectional view of a core portion of a fusion reactor, FIG. 2 is a comparative example, a vertical sectional view of a deep portion of the fusion reactor, and FIG. 3 is another embodiment of the present invention. In the example, it is a vertical cross-sectional view around the core of a fusion reactor. 1 ... Cryostat, 2 ... Vacuum container, 3 ... Toroidal coil, 4 ... Poloidal coil, 5 ... Plasma, 6 ... Shield, 7 ... Horizontal port, 9 ... First wall, 10 ... Diverter Plate, 11 ... Vertical port, 13 ... Vacuum measuring device, 14 ... Valve control device, 15 ... Conduit, 16 ... Valve, 17 ... Liquefaction storage container, 23 ... Vacuum signal, 24 ... … Valve open / close signal, 30 …… vacuum exhaust device, 31 …… conduit, 32 …… heating device, 35 …… conduit, 36 …… pressure reducing valve, 37 …… gas container, 38 …… exhaust device chamber, 39 …… Heating equipment room, 40 …… furnace room, 41 …… pipe room.

Claims (5)

[Claims] 1. A vacuum degree measuring device for detecting a vacuum degree of a vacuum container for generating plasma, a storage container for a liquid inert substance, and a conduit for connecting the storage container and the inside of the vacuum container through a valve. And a valve control unit which receives an output of the vacuum degree measuring device and outputs a signal for opening the valve when the degree of vacuum is equal to or lower than a predetermined value. 2. A peripheral installation device connected to a vacuum container for generating plasma via a port, an airtight storage chamber for independently storing the peripheral installation device, and a valve provided in the storage chamber. A fusion reactor protection device, comprising: a storage container for an inert substance connected thereto, wherein the air in the storage chamber is replaced with an inert gas at atmospheric pressure. 3. A cryostat, a vacuum container provided in the cryostat, a toroidal coil and a poloidal coil provided in the vacuum container, a port for communicating a peripheral installation device outside the cryostat with a vacuum device, and a vacuum container. In a fusion reactor provided with a first wall and a diverter plate provided on an inner wall, a vacuum degree measuring device for detecting a vacuum degree of a vacuum vessel, a storage vessel for a liquid inert substance, and this storage vessel, A conduit communicating with the inside of the vacuum container via a valve, and a valve control unit for receiving an output of the vacuum degree measuring device and outputting a signal for opening the valve when the vacuum degree is a predetermined value or less. A fusion reactor characterized by the following. 4. A cryostat, a vacuum container provided in the cryostat, a toroidal coil and a poloidal coil provided in the vacuum container, a port for communicating a peripheral installation device outside the cryostat with the vacuum container, and a vacuum container. In a fusion reactor including a first wall and a diverter plate installed on an inner wall, a storage chamber having an airtight structure for independently storing peripheral installation devices connected through the port, and this storage chamber And a storage container for an inactive substance, which is connected via a valve, to the storage chamber, wherein the air in the storage chamber is replaced with an inert gas at atmospheric pressure. 5. The fusion reactor according to claim 3 or 4, wherein the first wall and the diverter plate are made of graphite, beryllium, tungsten or molybdenum.