JPH01313794A - Structure of tritium breeding blanket - Google Patents

Abstract

PURPOSE:To easily and surely execute the construction by providing a passage of liquid lithium in which an insulating operation has been executed to two inside surfaces being orthogonal to a magnetic field and one inside surface being parallel to the magnetic field, in a liquid lithium self-cooling type tritium breeding blanket. CONSTITUTION:With respect to the inside surface of a structure which has been formed in advance, an insulating operation is executed to total three surfaces of two surfaces being orthogonal to a magnetic field 2 and one surface being parallel to the magnetic field, and insulating part 3 is formed thereby. The first wall structure 5 and a blanket container structure 6 which have been brought to insulating operation are joined with the respective plates 4 by a diffused junction method, etc. In such a way, the insulating operation can be executed easily and surely without necessitating a special device, and also, it can be inhibited that the insulating property of the insulating part is broken down.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is composed of a conductive material, such as the first wall or blanket in a nuclear melting reactor, and has a conductive material in a passage formed therein. The present invention relates to a structure of a liquid metal blanket that reduces flow resistance generated on the liquid metal side when the liquid metal is flowed in a direction across a magnetic field.

[Prior art] Figure 4 is an example of the prior art shown in JAERI-M87-017, which shows a tube-shaped structure designed for a practical fusion power reactor.
It is an in-shell type blanket, and is a perspective sectional view when the inner surface of the container wall is completely insulated. In FIG. 4, 51 is a proliferation region, 52 is a first wall, 53 is a plasma,
54 is an insulating part, 55 is a toroidal magnetic field, and 56 is a poloidal magnetic field. When conductive liquid metal flows in the direction of the poloidal magnetic field 56 in the breeding region 51 in a blanket subjected to high heat load and neutron irradiation from the plasma 53, the liquid metal flows in a direction transverse to the toroidal magnetic field 55. An electromotive force based on Faraday's law is generated in a conductor that moves across a magnetic field, and this causes a current to flow in the conductor that generates a force (Lorentz force) that impedes the conductor's motion. Therefore, a conductor moving across a magnetic field will experience resistance. This conductor causes a drop in fluid pressure similar to frictional resistance called MHD pressure drop in t% of a fluid such as liquid metal.

In this example of the prior art, as a means to reduce the drop in fluid pressure, the inner surface of the container wall of the propagator 1451 is entirely insulated, so that the current flowing in the fluid can pass through the channel wall made of a conductive material. This prevents the formation of a circuit that goes through and returns. In this case as well, a current circuit is formed inside the fluid and the above-mentioned MHD pressure loss occurs, but the value is extremely small at about 10-3 to 10-4 compared to the above-mentioned conductive wall basin 6. .

[Problem to be solved by the invention] As described above, even in the conventional technology, it is possible to reduce the MHD pressure loss to a practically negligible level by insulating the entire inner surface of the channel wall, and it is possible to This makes it possible to reduce the power of pumping the fluid flowing through the growth region, reduce the container wall thickness as the fluid inlet pressure decreases, and prevent the occurrence of unsafe conditions due to pressure fluctuations when the magnetic field is lost. Ta. However, in the above-mentioned conventional technology, the method of completely insulating the inner surface of the flow channel wall makes it difficult to insulate narrow channels such as the first wall channel and limiter channel when applying insulation coating after assembly. In addition, when assembling is performed after insulation work has been performed in advance, there is a possibility that the insulation at joints such as welds may be destroyed.

[Means for Solving the Problems] A means for solving the above problems is the structure of the tritium breeding blanket described in the claims.

That is, in a liquid lithium self-cooling type tritium breeding blanket, the tritium breeding blanket has a structure in which liquid lithium flow paths are insulated on two inner surfaces perpendicular to the magnetic field and one inner surface parallel to the magnetic field.

[Operation] Figures 3 (A), (B), and (C) show that tubes 11, 14, and 15 of different electrical conductivity are arranged in a direction transverse to the magnetic field 12 in a magnetic t% 12. This is a comparative explanatory diagram of the current circuit generated in a tube or fluid when a conductive fluid such as liquid metal flows, and the magnitude of MHD pressure drop based on the circuit.In Fig. 3, (A) (B) is the case where the tube 14 is an insulating wall, and (C) is the case where the tube 15 is a conductive wall.

Now, ΔP: MHD pressure drop B: Magnetic flux density σ: Fluid conductivity V2 Fluid velocity μ: Viscosity coefficient a: Channel radius σW: Electrical conductivity of wall material tll: Wall thickness Ha: Hartmann number, ΔP in each of (A) to (C) is as follows.

In the case of (A) (perfectly conductive type) ΔP=σB2V In the case of (B) (insulating wall) 1+φ− (Hasu(φ−・cl) The above (A), (B), and (C) are all fluids. Although the cross section of the passage is circular, a similar formula is also shown when the cross section of the fluid passage is square, and as shown in (A) and (C) above, the current flowing in the fluid flows through the flow path. In the case of a conductive wall, where a circuit returns through the wall, and in the case of an insulating wall, where a circuit is created in the fluid, as shown in (B) above,
There is a large difference in the value of the MHD pressure drop ΔP that occurs. For example, under typical conditions of a tokamak type fusion reactor, the MHD pressure drop ΔP in the case of a conductive type is equal to the MHD pressure drop ΔP in the case of an insulating wall.
It is 103 to 104 times that of P.

Table 1 shows the inner surface of a channel when a conductive fluid such as liquid metal flows through a channel having rectangular walls made of conductive material and placed in a magnetic field in a direction transverse to the magnetic field. It shows the correlation between the insulation state and the MHD pressure loss occurring in the fluid.

As is clear from Table 1, in order to reduce MHD pressure loss, it is not necessarily necessary to provide insulation on all four inner surfaces of the passage, but with insulation on two surfaces perpendicular to the magnetic field and one surface parallel to the magnetic field. Even by insulating only three sides, almost the same effect as insulating all four sides can be obtained.

Table 1 [Example] Figures 1 and 2 show examples based on the present invention.
The figure shows the procedure for insulating the first wall in a nuclear melting reactor, and the procedure for joining the insulated part and the flat plate of the non-insulated part.
FIG. 2 is a diagram showing a procedure for insulating a blanket container in a fusion reactor and a procedure for joining the insulated portion and the flat plate of the non-insulated portion. In Figures 1 and 2, 1 is a plasma, 2 is a magnetic field, 3 is an insulator, 4 is a flat plate, and 5 is a first
The wall structure, 6, is a blanket container structure. In FIG. 1, liquid lithium flowing in a passage formed by a first wall structure 5 and a flat plate 4 flows across a magnetic field (boloidal) 2, and in FIG.
The liquid lithium flowing through the passage constituted by the magnetic field (toroidal) 2 and the flat plate 4 flows across the magnetic field (toroidal) 2.

Therefore, if insulation is not provided on the inner surface of each passage, an electromotive force is generated in the fluid, and a circuit is created in which the current flowing in the fluid returns through the passage wall, which impedes the movement of the fluid.
This causes a drop in fluid pressure similar to frictional resistance called HD pressure drop.

This drop in fluid pressure reaches, for example, 10 MPa or more when liquid lithium flows through the inner blanket at a flow rate of about 0.3 +*/s in a container with a wall thickness of about 1 ozg. In order to reduce this, as shown in Figures 1 and 2, the inner surface of the pre-formed structure is insulated on a total of 3 sides, 2 sides perpendicular to the magnetic field 2 and 1 side parallel to the magnetic field. construction. That is, in FIGS. 1 and 2, this is the portion of the insulating portion 3 shown with diagonal lines on the inner surfaces of the first wall structure 5 and the Blanguette container structure 6. The first wall structure 5 and the blanket container structure 6, which have been insulated, are bonded to their respective flat plates 4 by a diffusion bonding method or the like. The first wall or blanket container, etc. manufactured by the method of joining the three-sided insulated structure and the flat plate constructed in this way will not have the insulating part destroyed during assembly, and the As described in No. 3, it is possible to obtain a low MHD pressure loss comparable to that of a non-conductive wall.

[Effects of the Invention] Since the present invention is configured as described above, it produces effects as described below.

In order to reduce the MHD pressure loss caused by conductive fluid flowing through a passageway in a conductive wall across a magnetic field, two sides perpendicular to the magnetic field and one side parallel to the magnetic field can be reduced without insulating the entire inner surface of the passageway. By insulating the walls, it has become possible to obtain a low MHD pressure drop effect that is almost the same as with full-scale insulation, and it has become possible to achieve a low MHD pressure drop effect that is almost the same as with full-scale insulation. Even when insulating the inner surface of a structure with It has become possible to perform construction easily and reliably without the need for Furthermore, by joining and assembling a structure for which insulation has been completed and a flat plate using a method such as diffusion bonding, it has become possible to prevent the insulation properties of the insulation portion from being destroyed.

[Brief explanation of the drawing]

Figures 1 and 2 show embodiments based on the present invention;
The figure shows the procedure for insulating the first wall in a fusion reactor, and the procedure for insulating the structure and the flat plate. Figure 2 also shows the procedure for insulating the blanket container, and the procedure for insulating the structure and the flat plate. It is a figure which shows the joining procedure. Figure 3 (A), (B
> and (C) are the circuits of the current generated in the tube and fluid when a conductive fluid flows through three types of tubes with different electrical conductivities arranged in a direction across the magnetic field. , is a comparative explanatory diagram of MHD pressure loss. FIG. 4 is an example of the prior art. 1...Plasma, 2...Magnetic field, 3...
...Insulating section, 4...Flat plate, 5...
First wall structure, 6...Blanguette container structure, 11.14.15...Tube, 12...
...Magnetic field, 13...Current, 51...
Proliferation region, 52...Single mouth L53...Plasma, 54...Insulating section, 55...Troidal magnetic field, 56...Boloidal magnetic field Figure 2 (A) (B) Figure 3

Claims (1)

[Claims] A structure of a liquid lithium self-cooling tritium breeding blanket characterized by having liquid lithium flow paths insulated on two inner surfaces perpendicular to the magnetic field and one inner surface parallel to the magnetic field.