JPH0233115B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a fast breeder reactor and a method for manufacturing the same, and more particularly, to an improvement in the structure of a roof slab equipment installation part and equipment installation method in a tank-type fast breeder reactor. It is related to.

[Background of the invention]

The sodium-cooled tank type fast breeder reactor has the eighth
As shown in the figure, a roof slab 2 is provided at the top of the reactor main vessel 1 to isolate the inside of the reactor from the outside world. A heat exchanger 3, a plurality of primary main circulation pumps 4, and a reactor core 5 are housed. Above the core 5, a control rod for controlling the output of the reactor and an upper core mechanism 6 for measuring the temperature and flow rate at the core outlet are installed. Furthermore, inside the reactor main vessel 1, high temperature sodium flowing out from the reactor core 5 and an intermediate heat exchanger 3 are stored.
Partition wall 7 that separates the low-temperature sodium that flows out further.
The interior of the main container is separated by the partition wall 7 into an upper hot plenum 8 and a lower cold plenum 9. After the sodium 10 in the reactor main vessel 1 is heated in the reactor core 5,
It flows out into the hot plenum 8, enters the intermediate heat exchanger 3, descends while imparting heat to the secondary cooling system sodium within the intermediate heat exchanger 3, and flows out into the cold plenum 9. The low temperature sodium in the cold plenum 9 is sent to the core 5 by the primary main circulation pump 4.

The roof slab 2, which is the upper lid of the reactor main vessel 1, isolates the inside of the reactor from the outside world, and also serves as a cold trap in addition to the main intermediate heat exchanger 3 and the primary main circulation pump 4 shown in FIG. , an auxiliary intermediate heat exchanger, and other devices are mounted through the roof slab 2.

The structure of the roof slab equipment penetration part is shown in FIG. 9, taking the intermediate heat exchanger 3 as an example.

In FIG. 9, the intermediate heat exchanger 3 is fixed on the upper surface of the roof slab 2 and has a structure that penetrates the roof slab 2, and a lower end open annular space 11 is formed in the equipment penetration part. On the other hand, regarding the roof slab 2 itself, it is necessary to maintain the upper surface 2' of the roof slab 2 at a temperature close to room temperature, and it is also necessary to reduce the radiation dose in the upper direction. High temperature sodium at approximately 500℃ 1
0 and cover gas (usually argon gas) layer 12
A heat shielding layer 2a that shields heat from the cooling layer 2b
and a radiation shielding layer 2c.

As is clear from the above description, during reactor operation, the upper surface of the roof slab 2 is at a temperature close to room temperature, while the cover gas layer 12 below the roof slab 2 is exposed to high temperature sodium 1 in the hot plenum 8.
0 results in high temperature. Therefore, the high temperature of the cover gas near the lower end open part 11' of the annular space 11 in the device penetration part is 300 to 400°C, and the upper end closed part 1
The temperature near 1" is about 50°C. Due to this temperature difference between the upper and lower sides, natural convection of the cover gas occurs in the annular space 11. This annular space 11
The natural convection of the cover gas in the area becomes a circular flow in the circumferential direction consisting of a high-temperature upward flow and a low-temperature downward flow, as shown in Fig. 10a, and the cylindrical device outer peripheral wall 3' has a circular flow as shown in Fig. 180. Temperature distributions as shown in b and c occur, resulting in nonuniform temperature distribution along the circumferential direction of the device outer peripheral wall 3'. As a result, thermal deformation as shown in FIG. 10d occurs in the device outer peripheral wall 3'. If the above-mentioned thermal deformation occurs in the equipment outer peripheral wall 3', harmful stress may be applied to the equipment members, or contact with the internal structure of the equipment or contact with the inner peripheral wall 2'' of the equipment penetration part of the roof slab 2 may occur. This will cause serious damage to the structural strength and functionality of the equipment.In addition, after the reactor has been shut down and cooled, each equipment may be pulled out of the roof slab 2 for the purpose of equipment maintenance, but deformation that occurs during operation may cause If any residue remains, the device may not be able to be removed.

Conventionally, in order to eliminate the uneven temperature distribution that occurs in the circumferential direction of the device penetration section, it has been thought that it is sufficient to prevent natural convection (circumferential circulation flow) in the annular space 11 of the device penetration section. , Japanese Patent Publication No. 1973
In addition to the method of providing a convection prevention material in the annular space 11, methods of reducing the gap in the annular space 11 have been considered, as shown in Japanese Patent Application Laid-Open No. 1403-1983 and Japanese Patent Application Laid-open No. 121193/1983.

In the former case, it is necessary to suppress convection by minimizing the gap between the convection preventive material and the roof slab (more specifically, the inner circumferential wall of the equipment penetration part); Making the gap between the penetrating portion and the inner circumferential wall of the penetrating portion extremely small causes manufacturing difficulties, and also makes maintenance such as insertion and withdrawal of equipment difficult. In addition, in the latter case, the gap between the penetrating device and the roof slab (inner circumferential wall of the device penetrating part) will need to be at least several mm to more than 10 mm, considering the insertion and withdrawal of the device. If such a gap exists between the roof slab (inner circumferential wall of the equipment penetration part), there is a concern that the effect of suppressing natural convection may be insufficient.

[Purpose of the invention]

The present invention was made as a result of various studies in order to solve the above-mentioned problems of the conventional technology. Eliminate uneven temperature distribution, reduce thermal deformation and thermal stress of equipment inserted and installed in the area, and at the same time maintain the structural strength and functional soundness of the equipment penetration part, and at the same time, install this type of structure. The present invention aims to provide a roof slab equipment installation part structure and equipment installation method in a tank-type fast breeder reactor that can be easily carried out.

[Summary of the invention]

In order to achieve the above object, the present invention provides a tank-type fast breeder reactor having a cylindrical equipment penetration in the roof slab of a reactor main vessel, in which a cylindrical equipment penetration is inserted into the inner circumferential wall of the equipment penetration in the roof slab and the equipment penetration. A plurality of vertical fins are provided protruding from each of the cylindrical outer peripheral walls of the equipment, and the vertical fins protruding from the inner peripheral wall of the equipment penetration portion of the roof slab and the vertical fins protruding from the equipment outer peripheral wall allow the equipment to penetrate. The first feature is that the annular space of the section is vertically divided into a plurality of sections in the circumferential direction.

The present invention also provides a method for manufacturing a tank-type fast breeder reactor, in which a cylindrical equipment penetration part is provided in the roof slab of a reactor main vessel, and predetermined equipment is inserted and installed in the equipment penetration part, in which equipment of the roof slab is installed. A plurality of vertical fins are protruded from the inner peripheral wall of the penetration part and the outer peripheral wall of the cylindrical equipment inserted into the equipment penetration part, and when inserting equipment into the equipment penetration part of the roof slab, The vertical fins protruding from the inner circumferential wall of the equipment penetration part and the vertical fins protruding from the outer peripheral wall of the equipment are set in advance in a separated state, and in this state, the above-mentioned equipment is inserted into the equipment penetration part of the roof slab, After the device is inserted, the device is rotated horizontally so that the vertical fins protruding from the inner peripheral wall of the device penetration portion of the roof slab and the vertical fins protruding from the device outer peripheral wall come into contact with each other. This is the characteristic of

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on the drawings. Figure 1 shows the main parts of the equipment penetration part of the roof slab in a tank-type fast breeder reactor to which the present invention is applied, taking the case of an intermediate heat exchanger as an example. FIG. 2 is a cross-sectional view of FIG. 1, and FIG. 3 is a developed view of FIG. 2.

As is clear from FIGS. 1 to 3, the inner peripheral wall 2'' of the equipment penetration part of the roof slab 2 and the equipment outer peripheral wall 3' inserted into the equipment penetration part have a plurality of vertical fins 2d and 3a, respectively. The vertical fins 2d protrude from the inner circumferential wall 2'' of the equipment penetration portion of the roof slab 2 and the vertical fins 3a protrude from the outer circumferential wall 3' of the equipment.
The annular space 11 of the device penetration portion is vertically divided into a plurality of spaces in the circumferential direction. In the illustrated embodiment, the inner circumferential wall 2'' side of the equipment penetration part of the roof slab 2,
4 vertical fins 2 on each side of the device outer wall 3'
d and 3a protrude, and the annular space 1 of the device penetration part
1 is vertically divided into four pieces in the circumferential direction.

As is clear from FIGS. 1 to 3, in the present invention, the annular space 11 of the equipment penetration part in the roof slab 2 portion is vertically divided into a plurality of parts in the circumferential direction. space 11
The natural convection due to the vertical temperature difference in the vertical direction becomes convection within each divided sector, and the
Circumferential circulation flow as shown in the figure does not occur.

The effects of the present invention were confirmed by calculations using a three-dimensional analysis program that handles the flow of incompressible and viscous fluids. This analysis program solves the conservation equations of mass, momentum, and energy for incompressible and viscous fluids, and can handle flows from laminar to turbulent regions for both forced convection and natural convection. Using this program, the calculation system was modeled with the following assumptions, and the natural convection characteristics of the annular space 11 were analyzed.

(1) Since the gap is sufficiently small compared to the height and circumference, we adopted the γ-θ-Z three-dimensional model shown in Figure 4 (γ direction: 3 meshes: side wall, fluid, and side wall).

(2) Density is constant except for the buoyancy term (Boussinesq approximation).

(3) The effect of the gap δ is expressed by the wall shear force F
Evaluated by.

F=fu ² /2gδ f=64/R _p f: Friction loss coefficient u: Flow velocity g: Gravitational acceleration R _p : Reynolds number (4) As the thermal boundary conditions of the inner and outer peripheral walls 2'' and 3' of the annular space 11, Heat transfer to the surroundings via the peripheral walls 2'' and 3' was considered.

Using the above model, natural convection characteristics in the 11 portion of the annular space were evaluated.

FIG. 5 shows an example of a flow velocity vector diagram due to natural convection in the annular space 11 portion of the device penetration portion. In addition, in Fig. 5, as shown in Fig. 5 a, the annular space is not divided into sectors (conventional).
and (b), the annular space is divided into sectors in the circumferential direction by vertical fins 2d and 3a (the present invention).

As shown in FIG. 5a, when the annular space is not divided into sectors, the convection flow forms a pair of circulation flows in the circumferential direction. On the other hand, if the annular space is divided into sectors as shown in FIG. 5b, the flow will not be circular in the circumferential direction as shown in FIG. 5a, but will be a flow with two vertical vortices. That is, by dividing the annular space into sectors in the circumferential direction, a large circumferential circulation flow is eliminated, and therefore the temperature difference generated in the circumferential direction is also reduced.

Here, the maximum temperature difference in the circumferential direction due to natural convection in the annular space will be evaluated. In addition, as the maximum temperature difference in the circumferential direction, a dimensionless temperature difference ΔT ^* obtained by the following equation was used as an evaluation index of the temperature difference.

ΔΤ ^* = Maximum circumferential temperature difference / Maximum temperature difference between upper and lower ends Figure 6 shows the maximum circumferential temperature difference ΔΤ ^* and Rayleigh number.
Shows the relationship with R _a . Here, the Rayleigh number R _a is a dimensionless number that is thought to govern natural convection and is expressed by the following equation.

R _a = G _r・P _r = gβΔΤl ³ /ν ²・P _r G _r : Grashof number P _r : Prandtl number β : Volumetric expansion coefficient ΔΤ : Temperature difference between upper and lower ends l : Representative length ν : Kinematic viscosity coefficient FIG. 6 shows a case where the annular space is not divided into sectors (conventional) and a case where the annular space is divided into sectors in the circumferential direction by vertical fins (the present invention).
The maximum dimensionless temperature difference between

As is clear from FIG. 6, when the annular space is divided into sectors in the circumferential direction, the temperature difference occurring in the circumferential direction becomes smaller. Therefore, according to the present invention, it is possible to alleviate thermal deformation and thermal stress due to a reduction in circumferential temperature difference. In addition,
The Rayleigh number in an actual device varies depending on each device, but is in the range of 10 ¹¹ to ^{10 12} .

By the way, in FIG. 2, the gap between the vertical fins 2d protruding from the inner peripheral wall 2'' of the equipment penetration part of the roof slab 2 and the vertical fins 3a protruding from the equipment inner peripheral wall 3' is an annular space. Considering that the circular flow in the circumferential direction within 11 can be more efficiently blocked, it is better to make the size as small as possible.

However, when inserting a predetermined device 3 into the device penetration portion of the roof slab 2, the vertical fins 2d protruding from the device penetration portion inner circumferential wall 2″ of the roof slab 2 and the device outer circumferential wall 3′ projecting from the beginning. If the vertical fins 3a are placed close to each other, the fins 2d and 3a will come into contact with each other during the insertion of the device 3, making it impossible to perform this type of work smoothly.

Therefore, in consideration of the above, when inserting the equipment 3 into the equipment penetration part of the roof slab 2, the seventh
As shown in Figure a, the vertical fins 2d protruding from the inner peripheral wall 2'' of the equipment penetration part of the roof slab 2 and the vertical fins 3a protruding from the equipment outer peripheral wall 3' are set in advance to be spaced apart. In this state, the device 3 is inserted into the device penetration part of the roof slab 2, and after the device is inserted, the device 3 is rotated horizontally so that the vertical fins 2d of the roof slab 2 and the vertical fins of the device outer peripheral wall 3' are connected. 3a, when the device is inserted, the inner circumferential wall 2'' of the device penetration part
It is possible to prevent the vertical fins 2d of the roof slab 2 from coming into contact with the vertical fins 3a of the equipment outer peripheral wall 3'.
can be inserted smoothly. In addition, when pulling out the equipment 3 from the equipment penetration part of the roof slab 2, what is necessary is just to perform the operation opposite to the said insertion operation.

[Effects of the Invention] The present invention is as described above, and according to the present invention, it is possible to eliminate the uneven temperature distribution that occurs at the penetration part of the roof slab, which could not be prevented with the prior art, and to prevent the unevenness of the temperature distribution that occurs in the penetration part of the roof slab. A roof slab for a tank-type fast breeder reactor that reduces thermal deformation and thermal stress of equipment, maintains the structural strength and functional integrity of the equipment penetrations, and facilitates the installation of this type of structure. The structure of the equipment installation part and the equipment installation method can be obtained.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of the main parts of an embodiment of a tank-type fast breeder reactor to which the present invention is applied, and FIG.
Figure 3 is a developed view of Figure 2, Figure 4 is a fluid characteristic analysis diagram for evaluating the effects of the present invention, and Figure 5 is a cross-sectional view of Figure 3.
Figure a is a fluid flow velocity vector diagram in a part of the reactor of a conventional (tank type) fast breeder reactor analyzed using the evaluation method shown in Figure 4, and Figure 5 b is a diagram of the fluid flow velocity vector in a part of the reactor analyzed using the evaluation method shown in Figure 4. Fig. 6 shows the maximum temperature in the circumferential direction in a part of the furnace of the conventional structure shown in Fig. 5a and the inventive structure shown in Fig. 5b. Difference-Rayleigh number characteristic diagram; FIG. 7a is a cross-sectional view showing the structure of the present invention shown in FIG. 1 before being set in the furnace;
FIG. 7b is a cross-sectional view of the structure of the present invention shown in FIG. 7a set in a reactor, FIG. 8 is a vertical cross-sectional view showing the overall internal structure of a tank-type fast breeder reactor, and FIG. The figure is a vertical sectional view of a part of the interior of a conventional (tank type) fast breeder reactor corresponding to the structure of the present invention shown in Figure 1, and Figure 10a is the interior of the conventional breeder reactor shown in Figure 9. A diagram showing a fluid convection pattern in a part, FIG. 10b is an axial temperature distribution characteristic diagram in a part of the reactor of the conventional breeder reactor shown in FIG.
Fig. 10c is a temperature distribution characteristic diagram in the circumferential direction in a part of the reactor interior of the conventional breeder reactor shown in Fig. 9, and Fig. 10d is a diagram of the convection pattern shown in Fig. 10a and
FIG. 10 is an explanatory diagram of equipment deformation when thermal deformation occurs in the in-reactor equipment of the conventional breeder reactor shown in FIG. 9 due to the temperature distribution shown in FIG. 0 b and FIG. 10 c. 1...Reactor main vessel, 2...Roof slab, 2''...
Inner peripheral wall of device penetration part, 2a... Heat shielding layer, 2b... Cooling layer, 2c... Radiation shielding layer, 2d... Vertical fin, 3
...Equipment (main intermediate heat exchanger is shown as an example),
3'...Equipment outer peripheral wall, 3a...Vertical fin, 4...Primary main circulation pump, 5...Reactor core, 6...Core upper mechanism, 7
...Partition wall, 8...Hot plenum, 9...Cold plenum, 10...Sodium, 11...Annular space, 12
...cover gas layer.

Claims (1)

[Scope of Claims] 1. In a tank-type fast breeder reactor having a cylindrical equipment penetration part in the roof slab of the reactor main vessel, the inner peripheral wall of the equipment penetration part of the roof slab and the cylindrical part inserted into the equipment penetration part. A plurality of vertical fins are provided protruding from each of the equipment outer peripheral walls, and the annular space of the equipment penetration part is formed by the vertical fins protruding from the equipment penetration part inner peripheral wall of the roof slab and the vertical fins protruding from the equipment outer peripheral wall. An equipment installation part structure of a roof slab in a tank-type fast breeder reactor, characterized in that the roof slab is vertically divided into a plurality of parts in the circumferential direction. 2. In a method for manufacturing a tank-type fast breeder reactor, in which a cylindrical equipment penetration part is provided in the roof slab of the reactor main vessel, and prescribed equipment is inserted and installed in the equipment penetration part, the inner circumferential wall of the equipment penetration part of the roof slab and the A plurality of vertical fins are provided protrudingly on the outer peripheral wall of the cylindrical equipment inserted into the equipment penetration part, and when the equipment is inserted into the equipment penetration part of the roof slab, a plurality of vertical fins are provided on the inner peripheral wall of the equipment penetration part of the roof slab. The protruding vertical fins and the vertical fins protruding from the outer peripheral wall of the equipment are set in a spaced state in advance, and in this state the equipment is inserted into the equipment penetration part of the roof slab, and after the equipment is inserted, the A tank-type high-speed multiplication device characterized in that the equipment is rotated in the horizontal direction so that vertical fins protruding from the inner peripheral wall of the equipment penetration part of the roof slab and vertical fins protruding from the equipment outer peripheral wall come into contact with each other. Equipment installation method for roof slabs in furnaces.