JPH0246919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in the cooling structure of a first wall forming a plasma facing surface of a blanket for a nuclear fusion reactor.

[Conventional technology] An overview of a tokamak-type fusion reactor will be explained.

A tokamak-type fusion reactor is one in which a current is passed through the plasma created along the circumference, and the plasma is confined by the force of the magnetic field generated by this current, which surrounds the plasma 1 as shown in Figure 1. Inner blanket 2, outer blanket 2', inner shield 3, outer shield 3', toroidal magnetic field coil 4, poloidal magnetic field coil 5, diverter 6,
An exhaust device 7 and the like are arranged.

A tokamak-type fusion reactor is generally composed of the equipment described above, and among these, the inner and outer blankets 2 and 2' are used to absorb the nuclear energy of neutrons generated by the fusion reaction inside the container. It has the following functions: converting the neutrons into thermal energy, producing tritium (tritium), which is the fuel for the fusion reactor by reacting the neutrons with lithium oxide in the container, and shielding the neutrons with a shield. It is one of the important pieces of equipment in a nuclear fusion reactor. The first wall is a structure that faces the plasma 1 of the inner and outer blankets 2, 2', and is under severe conditions where it is directly subjected to a large heat load and particle load from the plasma 1.
It is required to have sufficient cooling performance.

[Problem to be solved by the invention]

By the way, the first wall 8 of the tokamak type fusion reactor is
Conventionally, as shown in Fig. 2, cooling is performed by using a method in which the coolant flows in the poloidal direction, that is, in the direction of arrow A. However, because the shape is toroidal, the pitch of the coolant flow path is in the direction of the flow. The problem arises that it changes. In other words, the pitch of the coolant flow path is maximum at the plasma center plane B, which receives the severest heat load, and the pitch is minimum at the upper or lower part, where the heat load is relatively small, resulting in uneven cooling and the maximum temperature of the structural material. It is difficult to suppress the thermal stress inside the structural material below the allowable value, and
If the wall 8 is installed in front of the blanket container as a structure independent of the breeding blanket container, neutron deceleration and absorption will occur in both the first wall 8 and the wall of the blanket container, resulting in poor neutron economy and There are problems such as adverse effects on tritium breeding performance and difficulty in supporting the first wall 8 under severe heat load and particle load conditions, and it has been difficult to solve these problems.

Therefore, in view of the above technical problems, the present invention has been made to
The objective is to provide a cooling structure for the first wall of a fusion reactor that has excellent cooling performance and neutron economy.

[Means to solve the problem]

The cooling structure for the first wall of a fusion reactor according to the present invention for solving the above problems integrates the container wall of the box-shaped blanket and the first wall, and has a large number of channels that flow the coolant in a toroidal direction to the first wall. A coolant flow path is provided, and at least a pair of left and right coolant manifolds that distribute and collect the coolant flow path and also serve as reinforcing flanges for the blanket are provided on the rear side of the blanket, and the insides of the left and right manifolds are arranged at different levels on the left and right sides in the poloidal direction. The number of coolant passages connected to the divided manifold is increased on the coolant inlet side at the lower end of the coolant manifold, and is reduced on the cooling outlet side at the upper end of the coolant manifold, so that the coolant is routed through the divided manifold. The coolant is sequentially folded back and sent into the coolant flow path.
The first wall is cooled.

[Effect]

The first nuclear fusion reactor of the present invention configured as described above
According to the wall cooling structure, during furnace operation, the coolant passes through the manifold that divides the coolant flow path in the toroidal direction of the first wall, from right to left, → left to right, → right to left... Since the coolant flows in this order, the actual heat removal flow path length of the coolant becomes longer. In addition, the number of coolant flow paths connected to the divided manifolds is increased on the coolant inlet side and fewer on the coolant outlet side, resulting in less pressure loss in the coolant flow path and a lower coolant temperature at the coolant inlet. The flow velocity of the coolant in each of the side coolant channels becomes smaller, the flow rate becomes smaller, and the heat transfer coefficient becomes smaller. Then, the flow velocity of the coolant in each coolant flow path on the coolant outlet side where the coolant temperature is high increases, the flow rate increases, and the heat transfer coefficient increases. Therefore, the film temperature difference between the inlet and outlet sides of the coolant flow path is reduced, and the temperature of the structural material of the first wall is suppressed and flattened, suppressing the occurrence of thermal deformation and thermal stress, and suppressing the coolant flow. boiling is prevented.

〔Example〕

An embodiment of the cooling structure for the first wall for each fusion reactor according to the present invention will be described with reference to the drawings. FIG. 3 shows a cross section of a box-shaped blanket having a first wall that also serves as the container wall of the box-shaped blanket, where 10 is the first wall that also serves as the container wall of the blanket, and 11 is the first wall that cools the first wall 10. This is a coolant flow path through which coolant flows in a toroidal direction, and is connected to a pair of left and right manifolds 12a and 12b which also serve as reinforcing flanges 12 provided on the rear side of the blanket.

This pair of left and right manifolds 12a, 12b are
As shown in the conceptual diagram of the cooling system in Fig. 4, the interior is divided into a plurality of stages, three stages in this example, on the left and right in the poloidal direction. In order to adjust the ratio), the number of tubes is varied in the poloidal direction for each divided manifold. That is, on the coolant inlet 16 side at the lower end of the manifold 12a, the number of parallel coolant channels 11 is increased to reduce the flow velocity (thermal conductivity) of the coolant, and the manifold 1
On the coolant outlet 17 side at the upper end of 2b, the number of parallel coolant channels 11 is reduced to increase the flow velocity (heat transfer coefficient) of the coolant.

A tritium breeder material 13 and a neutron moderator 14 are stored inside the blanket container integrated with the first wall 10, and a coolant is applied in the poloidal direction at appropriate intervals between these materials. The coolant flow path 15 for cooling the blanket is the first
There are many on the wall 10 side, and fewer toward the rear.

Next, the operation of this embodiment configured as described above will be explained. The first wall 10 of the blanket in the fusion reactor is directly subjected to a severe heat load and particle load from the plasma, so it is necessary to cool the first wall 10 sufficiently.

In order to cool the first wall 10, during the reactor operation, the coolant is supplied into the coolant passage 11 of the first wall 10 from the coolant inlet 16 at the lower end of the right manifold 12a as shown in the conceptual diagram of the cooling system in FIG. Upon introduction of the coolant, the coolant flows from the divided manifold to the coolant flow path 11.
, to reach the divided manifold in the left manifold 12b. The coolant is now folded and passes through to the segmented manifold of the right hand manifold 12a. In this way, the coolant makes a U-turn using the divided manifolds in the manifolds 12a and 12b as headers, then makes a U-turn at the divided manifold through , and then makes a U-turn at the divided manifold through . , , to the divided manifold at the upper end of the left manifold 16b, and the coolant exits from the coolant outlet 17 as shown by the arrow.

In this way, the coolant flows through the coolant flow path 11 of the first wall 10 in order from right to left, → left to right, → right to left, etc., so that the actual coolant heat removal flow path is length becomes longer.

In addition, the number of coolant channels 11 connected to the divided manifolds is increased on the coolant inlet 16 side,
Since the coolant is kept at least on the side of the coolant outlet 17, the pressure loss in the coolant flow path 11 does not become excessive.
The flow velocity of the coolant in each coolant channel 11 on the side of the coolant inlet 16 where the coolant temperature is low decreases, the flow rate decreases, and the heat transfer coefficient decreases. The flow velocity of the coolant in each coolant channel 11 on the side of the coolant outlet 17 where the coolant temperature is high increases, the flow rate increases, and the heat transfer coefficient increases. Therefore, the film temperature difference between the inlet side and the outlet side of the coolant flow path 11 is reduced, the temperature of the structural material of the first wall 10 is suppressed and flattened, and the generation of thermal deformation and thermal stress is suppressed. Coolant boiling is prevented.

However, in a tokamak-type fusion reactor, the thermal load on the first wall 10 is greatest at the plasma center plane;
Although the distribution shows a considerably smaller distribution above and below the first wall 10, the number of coolant channels 11 is changed in order to average the temperature of the first wall structural material in the poloidal direction in response to such a distribution. By selecting
The occurrence of thermal deformation and thermal stress can be reduced.

Note that the cross-sectional shape of the coolant flow path 11 is not limited to a circular shape, but can also be shaped as an ellipse, semicircle, rectangle, etc., depending on the heat load distribution. Any suitable combination of channels may also be used.

〔Effect of the invention〕

As described above, the cooling structure of the first wall for a fusion reactor of the present invention integrates the first wall and the container wall of the box-shaped blanket, and provides a large number of coolant channels in the toroidal direction in the first wall. , the coolant flow path is connected to a divided manifold of a coolant manifold that also serves as reinforcing flanges provided at least one pair on the left and right on the rear side of the blanket to form a flow path for the coolant to flow in a folded manner;
In addition, since the number of coolant channels connected to the divided manifold is set to correspond to the heat load from the plasma, the film temperature difference between the inlet and outlet sides of the coolant channel is reduced, and the first wall This has the effect of suppressing and flattening the structural material temperature, suppressing the generation of thermal deformation and thermal stress, and preventing boiling of the coolant, improving cooling performance and neutron economy.

[Brief explanation of the drawing]

Fig. 1 is a sectional view schematically showing a tokamak type fusion reactor, Fig. 2 is a perspective view showing a schematic shape of the outer blanket/first wall, and Fig. 3 is a cooling of the first wall for a fusion reactor according to the present invention. A sectional view of a box-shaped blanket showing an example of the structure, FIG. 4 is a conceptual diagram of the cooling system of the cooling structure of the first wall, and FIG. 5 is a perspective view showing a part of the A-A cross section of FIG. 3. It is. 10...first wall, 11...coolant channel, 12...
...Reinforcement flange, 12a, 12b... Coolant manifold.

Claims (1)

[Claims] 1. Integrating the container wall of the box-shaped bracket and the first wall, providing a large number of coolant flow channels in which the coolant flows in a toroidal direction on the first wall, and distributing the coolant flow channels;
At least a pair of left and right coolant manifolds that gather together and also serve as reinforcing flanges for the blanket are provided on the rear side of the blanket, and the inside of the left and right manifolds is divided into a plurality of left and right steps in the poloidal direction,
The number of coolant flow paths connected to the divided manifold is increased at the coolant inlet side at the lower end of the coolant manifold, and decreased at the coolant outlet side at the upper end of the coolant manifold, and the coolant is sequentially folded back and cooled by the divided manifold. A first material for a nuclear fusion reactor, characterized in that the material is fed into a flow path to cool the first wall.
Wall cooling structure.