JPH0154676B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a blanket for a nuclear fusion device, and more particularly to a nuclear fusion device that effectively recovers tritium produced in a tritium breeder material.

[Background of the invention]

A tokamak type nuclear fusion device, which is one type of nuclear fusion device, will be explained as an example.

Figure 1 shows the upper half of a poloidal cross section of a tokamak-type fusion device. The plasma 1 is confined by a toroidal magnetic field and a poloidal magnetic field generated by a toroidal coil 5 and a poloidal coil 6. Outside the plasma 1, a blanket 3 is installed so as to surround it and produce tritium, which takes in neutrons generated by the nuclear fusion reaction to produce tritium, and which converts the kinetic energy of nuclear neutrons into thermal energy. Blanket 3
Of these, the surface facing plasma 1 is usually the first.
There is a surface called wall 2 that directly receives thermal radiation from plasma 1 and collisions of charged particles. A shield 4 is installed on the outside of the blanket 3 to surround it and prevent leakage of neutrons and gamma rays.

Blanket 3 is heat generation during tritium production,
Cooling is necessary to remove the heat caused by the conversion of neutron kinetic energy into thermal energy and the heat generated in the first wall (hereinafter collectively referred to as nuclear heat generation). To this end, as shown in FIG. 2, in the blanket 3, a tritium breeder cooling flow path is provided between the tritium breeder materials 8 to allow the cooling material to flow therethrough. The heat generated in the first wall is the plasma 1
10-20% of the heat generated in Further, inside the blanket 3, the tritium breeder material region closer to the plasma 1 has a higher density of neutrons flowing from the plasma 1, so the production amount of tritium is higher, and the heat generation density is correspondingly higher. For this reason, in the conventional blanket, as shown in Fig. 2, the plasma 1
The layer of the tritium breeder material is made thinner in the region of the tritium breeder material nearer to the area of the tritium breeder material, and the scattering density of the channels for cooling the tritium breeder material is increased. Usually, Li ₂ O is used as the tritium breeding material 8, and light water is used as the coolant for cooling inside the blanket. Furthermore, SUS is usually used for the cooling channel walls, the tritium breeding material 8, and the blanket container 7.

The tritium produced in the tritium breeder material 8 is continuously recovered by a tritium carrier, such as helium gas, flowing through the tritium breeder region. The temperature of the tritium breeder material required for continuous recovery of tritium is the optimum release temperature of 400°C to 1000°C, which is suitable for releasing tritium from the interstitial lattices of the tritium breeder material through thermal movement.

In conventional blankets, helium gas (thermal conductivity: 1.42
×10 ³ W/mK) and argon gas with low thermal conductivity (thermal conductivity 1.63 × 10 ² W/mK) was mixed in to lower the effective heat transfer coefficient in the tritium breeding region. As a result, the region of the tritium breeder material where the temperature is below the lowest temperature within the optimum temperature range for release is reduced.

However, mixing argon gas into helium gas to maintain the tritium breeder temperature within the optimum release temperature range has the following problems.

The first problem is that, by reducing the heat transfer coefficient of the tritium carrier, it is possible to reduce the tritium breeding region where the temperature is below the lowest temperature within the optimum release temperature range, but the temperature gradient in the tritium breeding material is large. As a result, the maximum temperature in the tritium breeder material increases and exceeds the maximum temperature of 1000°C.

The second problem is that the tritium carrier has two components, helium gas and argon gas, so argon gas and helium gas must be separated. The following process was used to separate tritium from helium gas.

(1) A mixed gas of helium gas and tritium gas flows into a catalytic oxidation reaction tower to oxidize tritium gas (T ₂ ) to T ₂ O. CO for catalyst
Use. Therefore, the tritium carrier contains helium gas (He), T ₂ O, CO, and CO ₂ .

(2) CO, CO ₂ and other impurities are removed by adsorption using a low-temperature adsorption trap at liquid nitrogen temperature.

(3) A mixed gas of He and T ₂ O is turned into ice by a cold trap using liquid nitrogen refrigerant, _and separated from He.

(4) Elevate and liquefy ice T ₂ O and use an electrolytic cell to
Convert to _T2 gas.

If argon gas is further mixed into the tritium carrier in addition to the complicated and difficult techniques described above, a technique for separating helium gas and argon gas will be required in addition to the above process.

Furthermore, the number of piping systems to the blanket increases by the amount of the argon gas system, making the piping even more complicated.

In this way, recovering tritium by mixing argon gas into the tritium carrier requires:
It has the drawbacks mentioned above.

[Purpose of the invention]

An object of the present invention is to provide a fusion device with a blanket that effectively recovers tritium produced in a tritium breeder.

[Summary of the invention]

The first means for achieving this purpose is to cool the tritium breeder material in at least one of the plurality of channels for cooling the tritium breeder material so that the temperature of the tritium breeder material in each region falls within the optimum temperature range for release. The reason is that the flow path resistance of the flow path is different from that of other channels for cooling tritium breeder material. Also,
The second means includes a flow path of at least one tritium carrier tube among the tritium carrier tubes attached to the plurality of tritium breeder material regions so that the temperature of the tritium breeder material in each region falls within the optimum release temperature range. The resistance is different from that of other tritium carrier tubes.

The temperature of the tritium breeder material depends exactly on the flow rate of both the cooling material and the tritium carrier once the thickness of each tritium breeder material is determined. However, the cooling effect of the coolant is much larger than that of the tritium carrier. In addition to this, the lowest temperature of the tritium breeder material occurs at the interface between the tritium breeder material, which has a large fluid resistance in the tritium carrier, and the tritium breeder material cooling channel.
It can be said that the minimum temperature of the tritium breeder material is determined by the flow rate of the cooling material. On the other hand, if the minimum temperature of the tritium breeder material is determined by the flow rate of the cooling material, the maximum temperature of the tritium breeder material is determined by the flow rate of the tritium carrier. In this sense, it can be said that the maximum temperature of the tritium breeder material is determined by the flow rate of the tritium carrier. Generally, as the flow rate increases, the cooling effect increases, so the maximum temperature of the tritium breeder material is inversely proportional to the tritium carrier flow rate and occurs in the center of the tritium breeder material.

Based on the above qualitative discussion, the operation of the means of the present invention will be described. The closer to the plasma, the greater the amount of nuclear heat generation in the tritium breeder material region, so the closer to the plasma, the smaller the flow path resistance of the tritium breeder cooling channel and the greater the flow rate of the cooling material. The maximum temperature of the tritium breeder material also depends on the thickness of the tritium breeder region, and the thicker the region, the higher the temperature. Therefore, depending on the thickness distribution of each tritium breeder material region, there will be a region where the maximum temperature of the tritium breeder material exceeds 1000°C. If there is a region where the temperature exceeds 1000°C using only the cooling material, the maximum temperature can be further lowered by changing the flow path resistance of each tritium carrier tube and adjusting the flow rate of the tritium carrier. As a result, the temperature of the tritium breeder material can be maintained within the optimum release temperature range.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to Examples. Third
The figure shows a schematic diagram of a blanket for a nuclear fusion device that is an embodiment of the present invention. In FIG. 3, reference numeral 8 denotes a tritium breeder material region, which is divided into four in this example; 9 is a cooling channel for each tritium breeder material region; 10 is an inlet for cooling material, such as light water;
1 is an outlet for the cooling material, 12 is an inlet for a tritium carrier, for example, helium gas, and 13 is an outlet for the tritium carrier. The cooling material enters the blanket container through the inlet 10;
The amount of heat generated by nuclear heat generation is absorbed through the flow path 9 and exits from the blanket container through the outlet 11. The tritium carrier enters each tritium breeder region from the inlet 12, passes through the gaps between the porous or pelleted tritium breeder materials, becomes mixed gas with tritium produced from the tritium breeder material, and flows out the outlet. From 13, go out of the blanket container.

The closer the tritium breeding region is to the plasma, the greater the nuclear heat generation. Therefore, a structure for maintaining the temperature of the tritium breeder material within the optimum release temperature range of 400 DEG C. to 1000 DEG C. is shown in FIGS. 4 and 5. FIG. 4 is a longitudinal sectional view of FIG. 3. In FIG. 4, 8 is a tritium breeding material, 9 is a cooling channel, 10 is an inlet for the cooling material, and 12 is an outlet for the tritium carrier.
The minimum temperature of each region of tritium breeder material is determined by the flow rate of the cooling material surrounding the outside of each region. In Figure 4, in the region of the tritium breeder material near the plasma where the nuclear calorific value is high, the channel width is increased so that the flow rate surrounding it is large.
In addition, a blanket structure is shown in which the channel width is narrowed so that the flow rate surrounding the tritium breeder material region far from the plasma, which has a small nuclear calorific value, is small.

FIG. 5 is a cross-sectional view of FIG. 3. Figure 5a
In the figure, 7 is a blanket container, 8 is a tritium breeder material region, 9 is a cooling channel, 10 is an inlet for cooling material, 12 is an outlet for a tritium carrier, and 14 is an orifice. In this example, the orifice is installed on the outflow side of the tritium carrier, but it may be installed on the inflow side of the tritium carrier. The maximum temperature of each tritium breeding region is
Inversely proportional to the tritium carrier flow rate. Generally, in the tritium breeding region close to the plasma where the nuclear calorific value is large, the maximum temperature in the region is higher than the maximum temperature in the tritium breeding region away from the plasma. Therefore, the closer the tritium breeding region is to the plasma, the higher the flow rate of the tritium carrier is to increase the maximum temperature of each tritium breeding region.
Keep the temperature below 1000℃. FIG. 5c shows the above case, and in order to increase the flow rate of the tritium carrier as the tritium breeding region gets closer to the plasma, an orifice is installed at the injection or pouring port for each tritium breeding region of the tritium carrier tube 15. However, the thickness of the orifice is made thinner as it gets closer to the plasma. That is, in FIG. 5b, 1 shows the aa' cross section, 2 the b-b' cross section, 3 the c-c' cross section, and 4 the dd' cross section. Also the fifth
Figure c shows the ee' cross section.

FIG. 6 shows an example of the temperature distribution in the blanket growth region in the blanket structure shown in FIG. In Figure 6, the fusion output is 440 MW, the blanket width is 50 cm, the cooling material is light water, the tritium carrier is helium gas, the tritium breeder is Li ₂ O, the blanket container, the tritium breeder material case, the cooling pipe, and the tritium carrier pipe are all made of SUS. This is the case. When the temperature distribution of the tritium breeder material is not adjusted, the maximum temperature in region 1 is 855°C, which is the highest among all regions. The lowest temperature in region 4 is 215°C, which is the lowest of all the regions. As described above, there is a region that is not included in the range of the optimum release temperature of tritium breeder material from 400°C to 1000°C. As conventional technology, when using a tritium carrier in which argon gas is mixed with helium gas, the heat transfer coefficient of the tritium carrier flowing between the cooling material and the tritium breeding material becomes small, so the tritium carrier that is closest to the cooling material The temperature in the breeding region is higher than when only helium gas is used as the tritium carrier. Along with this, the maximum temperature of the tritium breeder material in each region increases. In the present invention, in order to keep the temperature of the tritium breeder material in each region within the optimum release temperature range, the conventional cooling material flow path width at a rate of 5 mm is changed to 5 mm, 5 mm, and 3.6 mm.
mm, change to 2.4mm. This brings the lowest temperature of each region within the optimum emission temperature. Next, the flow rate of the tritium carrier in each region (1 to 4) is adjusted using an orifice. In Figure 6, since the minimum temperature in the 3rd and 4th regions has been raised to 400°C, the maximum temperature in the 3rd and 4th regions has increased to nearly 1000°C, so the tritium carrier flow rate has been increased by 1.2 times in both the 3rd and 4th regions. This is what I did. In this example, the orifice is
An orifice was attached to the tritium carrier injection and spout in two areas.

The flow rate of the tritium carrier is shown below. In the case of a nuclear fusion output of 440 MW, the amount of heat that must be cooled by both the cooling material and helium gas is 352 MW. In order to control the temperature of the tritium breeder material with the flow rate of helium gas, it is necessary to adjust 35MW, which is 10% of the 352MW, to vary the temperature difference of the tritium breeder material to about 100°C. For example, when helium gas is used as the tritium carrier, its constant pressure specific heat C is C=5.2 J/gK.
If the temperature difference in the cooling material is 50°C between the inlet and outlet of the blanket, then the temperature difference between the inlet and outlet of the tritium carrier blanket is 50°C. The flow rate X of the tritium carrier gas that should flow into the blanket is calculated by dividing the above temperature difference by ΔT (=50℃) and the amount of heat W (=
35MW), then from X=W/C・ΔT, X=
It is 141Kg/s.

As a result, the temperature of the tritium breeder material can be maintained within the optimum release temperature of 400°C to 1000°C. Also,
Since argon gas is not used, there is no need to separate argon gas from the tritium carrier.
The tritium recovery system is not complicated.

Other embodiments of the present invention will be shown below. Figures 7 and 8 show an embodiment in which a spacer is used to adjust the width of the cooling material flow path. In FIGS. 7 and 8, 16 is a spacer. In this embodiment, the cooling material flow path width 9 between each tritium breeding region is constant. The flow rate of the cooling material is adjusted by the number of spacers installed in the flow path. The closer the tritium breeding region is to the plasma, the greater the amount of nuclear heat generation, so the closer the tritium breeding region is to the plasma, the smaller the number of spacers is.

FIG. 9 shows another embodiment of the invention. In FIG. 9a, in order to adjust the flow rate of the tritium carrier, the diameter of the tritium carrier tube is adjusted without using an orifice. The closer the tritium breeding region is to plasma, where the nuclear calorific value increases,
This is a blanket structure in which the diameter of the injection or outlet port of the tritium carrier tube 15 into the tritium multiplication region is increased. In Figure 9b, 1 is a
2 shows the bb' cross section, 3 shows the c-c' cross section, and 4 shows the d-d' cross section.

FIG. 10 shows another embodiment of the invention. 10th
In the figure, 7 is the blanket container, 8 is the tritium breeding region, 10 is the inlet of the cooling material into the blanket, 11 is the outlet of the cooling material from the blanket, 12 is the inlet of the tritium carrier into the blanket, 13 17 is a pipe for the flow path of the cooling material between the tritium carrier blankets, 18 is the pipe for the cooling material between each tritium breeding region, and 19 is for the plasma. This is the blanket wall facing the room.

The cooling material enters the blanket container 7 through the inlet 10 and flows through channels 17 and 1 composed of cooling pipes.
8, absorbing the amount of heat generated by nuclear heat generation,
It exits the blanket container 7 through the outlet 11.
The tritium carrier enters each tritium breeding region in the blanket container 7 through the injection port 12, passes through the gaps between the tritium breeding materials, becomes a mixed gas with tritium generated from the tritium breeding material, and exits the blanket from the spout 13. Go out of container 7.

In this embodiment, the strength of the blanket structure is increased by arranging cooling pipes to form a flow path for the cooling material.

The minimum temperature of each tritium breeding region is determined by the flow rate of the cooling material surrounding each region. It is necessary to maintain the temperature of the tritium breeder material at 400°C to 1000°C, which is suitable for releasing tritium. In order to maintain the minimum temperature of each tritium breeding region at 400°C or higher, the diameter of the cooling pipe 18 is adjusted so that the flow rate of the cooling material surrounding the tritium breeding region, which has a large amount of nuclear heat and is close to plasma, is large. In addition, the diameter of the cooling pipe 18 is made small so that the flow rate of the cooling material surrounding the tritium breeding region, which has a small nuclear calorific value and is far from the plasma, is small. The method shown in FIG. 6 is used to change the diameter of the cooling pipe.

The maximum temperature of each tritium breeding region is inversely proportional to the tritium carrier flow rate. The temperature of the tritium breeder material must be maintained at the above 400°C to 1000°C. In order to keep the maximum temperature of each tritium breeding region below 1000℃, the closer the tritium breeding region is to the plasma, the greater the nuclear heat generation, and the maximum temperature in the above region is more common than the maximum temperature in the region far away from the plasma. Therefore, the flow rate of the tritium carrier should be increased. For example, the flow rate of the tritium carrier is changed in each region by the method shown in FIGS. 5 and 9.

FIG. 11 shows another embodiment of the invention. 11th
In the figure, 7 is the blanket container, 8 is the tritium breeding region, 10 is the inlet of the cooling material into the blanket, 11 is the outlet of the cooling material from the blanket, 12 is the inlet of the tritium carrier into the blanket, 13 17 is a pipe for the flow path of the cooling material between the tritium carrier blankets, 18 is the pipe for the cooling material between each tritium breeding region, and 19 is for the plasma. Blanket wall facing, 2
0 is the tritium carrier inlet to each tritium breeding region. The injection port 20 has a tritium carrier flow rate regulator 21, which changes the flow rate depending on the temperature of the tritium breeder material, for example. A flow regulator made of bimetal is installed.

The cooling material enters the blanket container 7 through the inlet 10 and flows through channels 17 and 1 composed of cooling pipes.
8, absorbing the amount of heat generated by nuclear heat generation,
It exits the blanket container 7 through the outlet 11.
The tritium carrier enters the blanket vessel through the inlet 12 and passes through the flow regulator 20 into each tritium breeding zone. The tritium carrier passes through the gap in the tritium breeding material, becomes a mixed gas with tritium produced by the tritium breeding material, and exits from the blanket through the spout 13.

This embodiment is characterized in that the flow rate of the tritium carrier entering each tritium breeding region is changed in accordance with the temperature change of the tritium breeding material.
This tritium carrier flow rate regulator 20 is installed at a location where the tritium breeder material has the highest temperature within each region. For example, when the flow rate regulator 20 is installed approximately in the center of each tritium breeding region, as shown in FIG.
are installed at two locations within the tritium breeding region so that tritium carriers flow uniformly within the tritium breeding region. The temperature of the tritium breeding material is 400℃ to 1000℃, which is suitable for releasing tritium.
To adjust the flow rate of the cooling material and the tritium carrier to maintain the
Any method shown in the figure can be used.

In this example, the flow rate of the tritium carrier can be changed in accordance with the temperature change of the tritium breeder, so even if the assumed nuclear fusion output fluctuates and the amount of nuclear heat generated in the blanket changes, tritium can be released. The temperature of tritium breeder material can be maintained at 400℃~1000℃, which is suitable for

〔Effect of the invention〕

According to the present invention, the temperature of the tritium breeder material can be maintained within a temperature range suitable for releasing tritium without mixing argon gas into the tritium carrier, so tritium produced in the tritium breeder material can be effectively recovered. can do.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the upper half of a poloidal cross section of a fusion device, Fig. 2 is a schematic diagram of a blanket of a conventional fusion device, and Fig. 3 is a schematic diagram of a blanket of a fusion device that is an embodiment of the present invention. FIG. 4 is a vertical cross-sectional view of the blanket of the present invention, FIG. 5 is a cross-sectional view of the blanket of the present invention, FIG. 6 is a diagram showing the temperature distribution of the blanket growth region, and FIG. FIG. 8 is a three-dimensional view of a blanket according to another embodiment of the present invention, FIG. 9 is a cross-sectional view of another embodiment of the present invention, and FIGS. FIG. 11 is a three-dimensional view of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Plasma, 2... First wall, 3... Blanket, 4... Shielding body, 5... Toroidal coil, 6... Poloidal coil, 7... Blanket container, 8... Tritium breeder material, 9... Tritium breeding cooling channel, 10... Inlet for cooling material, 11... Outlet for cooling material, 12... Inlet for tritium carrier, 13... Outlet for tritium carrier, 14... Orifice, 15 ……
Tritium carrier tube, 16... Spacer, 1
7... Channel for cooling material, 18... Channel for cooling material between tritium breeding regions, 19... Blanket wall facing plasma, 20... Tritium carrier inlet to each tritium breeding region, 21 …
...Tritium carrier flow regulator.

Claims (1)

[Claims] 1. Installed so as to surround the outside of the plasma,
In a fusion device comprising a blanket having a tritium breeder region divided by a plurality of tritium breeder cooling channels, the blanket is arranged so that the temperature of each tritium breeder region falls within a range of 400°C to 1000°C. , at least one of the plurality of flow path resistances of at least one of the flow path resistance of the tritium breeder material cooling flow path or the flow path resistance of the tritium carrier tube attached to the tritium breeder material region. A fusion device that is characterized by being different from others. 2. A nuclear fusion device according to claim 1, characterized in that the flow path resistance of the tritium breeder material cooling flow path is varied by changing the flow path width of the cooling material. 3. The nuclear fusion device according to claim 1, wherein the flow path resistance of the tritium carrier tube is varied by changing the diameter of an orifice provided in the tritium carrier tube. 4. The nuclear fusion device according to claim 1, wherein the flow path resistance of the tritium carrier tube is varied by changing the diameter of the tritium carrier tube.