JPS61142490A - Apparatus installing section structure and apparatus installing method of roof slab in tank type fast breeder reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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]

As shown in Figure 8, a sodium-cooled tank type fast breeder reactor is provided with a roof slab 2 located above the reactor main passenger equipment 1 to isolate the inside of the reactor from the outside world. Inside the main passenger unit 1, a plurality of main intermediate heat exchangers 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, a partition wall 7 is installed in the reactor main customer unit 1 to separate high temperature sodium flowing out from the reactor core 5 and low temperature sodium flowing out from the intermediate heat exchanger 3.
This partition wall 7 separates the inside of the main container into an upper hot plenum 8 and a lower cold plenum 9. After being heated in the reactor core 5, IJium 10 flows into the hot plenum 8, enters the intermediate heat exchanger 3, and enters the secondary cooling system within the intermediate heat exchanger 3. It descends while giving heat to the sodium 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 passenger unit 1, isolates the inside of the reactor from the outside world, and in addition to the main intermediate heat exchanger 3 and the primary main circulation pump 4 shown in FIG. 8, the roof slab 2 serves as a cold trap, A large number of devices, such as an auxiliary intermediate heat exchanger, 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 above 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 device penetration part. On the other hand, for 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 necessary to reduce the radiation dose in the upper direction. It is composed of a heat shielding layer 2a that shields heat from the 500C high temperature sodium 10 and a cover gas (usually argon gas) layer 12, a cooling layer 2b, and a radiation shielding layer 2C.

As is clear from the above description, during nuclear 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 heated to a temperature of about 10% of the high temperature sodium chloride in the hot plenum 8. It becomes high temperature. For this reason, the cover gas temperature near the lower end open part 11' of the annular space 11 in the device penetration part is 300 to 400 C, and the temperature near the upper end closed part 11'' is about 5.OC. As a result, natural convection of the cover gas occurs in the annular space 11.The natural convection of the cover gas in the annular space 11 consists of a high temperature upward flow and a low temperature downward flow, as shown in FIG. The flow becomes a circular flow in the circumferential direction consisting of
A temperature distribution as shown in Figure 0 (b) and (c) K occurs,
This results in non-uniform temperature distribution along the circumferential direction of the device outer peripheral wall 3'.

As a result, thermal deformation occurs on the outer peripheral wall 3' of the device as shown in FIG. 1(d). If the above-mentioned thermal deformation occurs in the equipment outer peripheral wall 3', harmful stress may be applied to the equipment components, contact with the internal structure of the equipment, or damage to the roof slab-2.
Contact with the inner circumferential wall 2" of the device penetration part will occur,
This will cause serious damage to the structural strength and functionality of the equipment. Also,
After the reactor has been shut down and cooled, each piece of equipment may be pulled out from the roof slab 2 for the purpose of equipment maintenance.
If the deformation that occurred during operation remains, it may become impossible to pull out the equipment.

Conventionally, in order to eliminate the uneven temperature distribution that occurs in the circumferential direction of the device penetration section, the annular space 11 of the device penetration section has been
Based on the idea that it is sufficient to prevent natural convection (circumferential circulation flow) in the parts, as shown in JP-A-54-1403 and JP-A-55-121193,
In addition to the method of providing a convection prevention material in the annular space 11, methods of reducing the gap of the annular space 11 have been considered.

However, 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 device (the inner circumferential wall of the device penetrating portion) extremely small causes manufacturing difficulties, and also makes maintenance such as insertion and withdrawal of the device difficult. In the latter case, the gap between the penetrating device and the roof slab (inner circumferential wall of the device penetrating portion) will need to be at least several to several dozen times, considering the insertion and removal work of the device. If a gap of this magnitude 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 prior art, and its purpose is to prevent problems that occur at the equipment penetration part of the roof slab, which could not be prevented with the prior art. It eliminates uneven temperature distribution, reduces thermal deformation and thermal stress of equipment inserted into the core, and at the same time maintains the structural strength and functional integrity of the equipment penetration part, and at the same time It is an object of the present invention to provide a structure of an equipment installation part of a roof slab in a tank-type fast breeder reactor, which can be easily installed, and a method of installing the equipment.

[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 part in the roof slab of the reactor main vessel, which is inserted into the inner peripheral wall of the equipment penetration part of the roof slab and the equipment penetration part. A plurality of vertical fins are provided protruding from each of the cylindrical outer circumferential walls of the equipment, and the vertical fins protruding from the inner circumferential wall of the equipment penetration portion of the roof slab and the vertical fins protruding from the outer circumferential wall of the equipment The first feature is that the annular space of the penetration part is vertically divided into a plurality of parts 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 respectively provided protrudingly on the inner peripheral wall of the penetration part and the outer peripheral wall of a cylindrical device inserted into the equipment penetration part, and the equipment is set in the equipment penetration part of the roof slab in a spaced state, In this state, insert the above-mentioned device into the device penetration part of the roof slab, and after inserting the device, rotate the device horizontally to connect the vertical fins protruding from the inner peripheral wall of the device penetration part of the roof slab and the device outer peripheral wall 3.
The second step is to bring the vertical fins 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 is a longitudinal cross-section of the main part showing 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. It is a front view.

Further, the wcz diagram 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 one roof slab 2 and the outer peripheral wall 3' of the equipment inserted into the equipment penetration part each have several vertical fins 2d and 3a protrudes from the roof slab 20, and includes nine vertical fins 2d protruding from the inner circumferential wall 2'' of the equipment penetration part and vertical fins 3a protruding from the equipment outer circumferential wall 3'. The annular space 11 of the section is vertically divided into a plurality of spaces in the circumferential direction. In the illustrated embodiment, four vertical fins 2d and 3a are provided protruding from the inner peripheral wall 2'' side of the roof slab 20 and the equipment outer peripheral wall 3' side, respectively, to form the annular space 11 of the equipment penetration part. 4 in that circumgonal crystal
The case of vertical division into 11I is shown.

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. The natural convection caused by the temperature difference in the vertical direction of the space 11 becomes a convection within each divided sector, and a circumferential circulation flow as shown in FIG. 10 does not occur.

The effects of the present invention were confirmed by calculations using a three-dimensional analysis program that deals with the flow of incompressible and viscous fluids.

This analysis program deals with incompressible and viscous fluids.
It solves the conservation equations of mass, momentum, and energy, and can handle flows from laminar to turbulent regions for both forced convection and natural convection. Using this program, a 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 of one circumference, we adopted the ``-θ-23-dimensional model shown in Figure 4 (
r direction: side wall, fluid, side wall 3 mesh 5-).

(2) The density is constant except for the buoyancy term (9ou
ss 1nesq approximation).

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

p=fu”/2ga.

f==64/R.

f: Friction loss coefficient U: Flow velocity g: Gravitational acceleration Ro: Reynolds number (4) As a thermal boundary condition of the inner and outer circumferences 112'' and 3' of the annular space 11, the Heat transfer 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 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 as shown in FIG. Figure 9 shows both the divided case (this invention) and the divided case (this invention).

As shown in FIG. 5(a), when the annular space is not divided into sectors, convection forms a pair of circulation flows in the circumferential direction.

On the other hand, when the annular space is divided into sectors as shown in Figure 5(b)K, a circumferential circulating flow as shown in Figure 5(a)K does not occur, but a flow with two vertical vortices. becomes.

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 occurring in the circumferential direction is also reduced.

Here, the maximum temperature layer 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.

FIG. 6 shows the relationship between the circumferential maximum temperature difference ΔTl and the Rayleigh number R. Here, the Rayleigh number R1 is a dimensionless number that is thought to govern natural convection and is expressed by the following formula % G: Grashoff number P, Nybrandtl number β: Volumetric expansion coefficient ΔT: Upper and lower end temperature difference t: Representative length :Kinematic viscosity coefficientIn addition, in Fig. 6, the maximum dimensionless temperature difference between the case where the annular space is not divided into sectors (conventional) and the case where the annular space is divided into sectors in the circumferential direction by vertical fins (invention) is shown. showed that.

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 circulation flow. The Rayleigh number applied to the actual machine varies depending on the busyness of each equipment, but is in the range of 1011 to 1012. The gap between the fins 2d and the vertical fins 3a protruding from the device outer peripheral wall 3' should be as small as possible in order to more efficiently block the circulation flow in the circumferential direction within the annular space ll. Good.

However, when inserting the equipment penetration part of the roof slab 2 (predetermined equipment 3), from the beginning, the vertical fins 2d protruding from the equipment penetration part inner peripheral wall 2''K of the roof slab 20 and the equipment outer peripheral wall 3'. If the vertical fins 3a are kept close to each other, the fins 2d and 33 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 20, it is necessary to
As shown □, roof slab 20 equipment penetration inner peripheral wall 2"
The vertical fins 2d protruding from the roof slab 2d and the vertical fins 31 protruding from the device outer peripheral wall 3' are set in advance to be separated from each other, and in this state the device 3 is attached to the roof slab 2.
After inserting the device into the device penetration part, rotate the device 3 horizontally so that the vertical fin 2d of the roof slab 2 and the vertical fin 3a of the device outer peripheral wall 3' come into contact with each other. When inserting the equipment, it is possible to prevent the vertical fins 2d of the inner peripheral wall 2'' of the equipment penetration part from coming into contact with the vertical fins 3a of the equipment outer peripheral wall 3', thereby preventing the insertion of the equipment 3 into the equipment penetration part of the roof slab 20. This can be done smoothly.In addition, when pulling out the equipment 3 from the equipment penetration part of the roof slab 2, it is sufficient to perform the operation opposite to the above-mentioned insertion operation.

〔Effect of the invention〕

The present invention is as described above, and according to the present invention, uneven temperature distribution occurring at the equipment penetration part of the roof slab, which could not be prevented with the conventional technology, can be prevented when e<L, the equipment inserted into the core part. A roof slab for a tank-type fast breeder reactor that reduces thermal deformation and thermal stress, maintains the structural strength and mechanical integrity of the above-mentioned equipment penetrations, and also facilitates the installation of this type of structure. A device installation part structure and a device installation method can be obtained.

[Brief explanation of the drawing]

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; FIG. 2 is a cross-sectional view of FIG. 1;
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 (a) is a conventional Wc tank base analyzed by the evaluation method shown in Figure 4). A fluid flow velocity vector diagram in a part of the reactor interior of a fast breeder reactor (Fig. 5) is a fluid flow velocity vector diagram of the structure of the present invention analyzed by the evaluation method shown in Fig. 4, and Fig. 6 is a fluid flow velocity vector diagram ) and the structure of the present invention shown in J 5 +; 7 is a cross-sectional view showing the structure of the present invention shown in FIG. 1 in a state before it is set in a furnace.
Figure (b) is a cross-sectional view of the structure of the present invention shown in Figure 7 (, I) set in the reactor, and Figure 8 is a vertical cross-section showing the overall internal structure of the tanker fast breeder reactor. Figure 9 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 1O (
a) is a diagram showing the fluid convection pattern in a part of the reactor interior of the conventional breeder reactor shown in FIG. 9, and FIG. 10(b) is a diagram showing the axial direction in a part of the reactor interior of the conventional breeder reactor shown in FIG. FIG. 10(C) is a temperature distribution characteristic diagram in the circumferential direction in a part of the reactor of the conventional breeder reactor shown in FIG.
Figure (d) shows the internal equipment of a conventional breeder reactor shown in Figure 9 due to the convection pattern shown in Figure 10 (a) and the temperature distribution shown in Figures 10 (b) and 1θ (c). FIG. 3 is an explanatory diagram of equipment deformation when thermal deformation occurs. 1... Reactor main vessel, 2... Roof slab, 2".
・Inner peripheral wall of device penetration part, 21 ・Heat shielding layer, 2b ・・
- Cooling layer, 2C...Radiation shielding layer, 2d...Vertical fin, 3...Equipment (as an example, the main intermediate heat exchanger is shown), 3'...Equipment outer peripheral wall, 3a...・Vertical fin,
4... Primary main circulation pump, 5... Core, 6... Core upper mechanism, 7... Bulkhead, butt... Hot plenum, 9
...cold plenum, 10...sodium, 11
...Annular space, 12...Cover gas layer.

Claims (1)

[Scope of Claims] 1. In a tank 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 the equipment outer peripheral wall of the roof slab. An equipment installation structure of a roof slab in a tank-type fast breeder reactor, characterized in that a space 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 predetermined 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 protruding from each of the cylindrical outer peripheral wall of the equipment to be inserted into the equipment penetration part, and when the equipment is inserted into the equipment penetration part of the roof slab, the inner peripheral wall of the equipment penetration part of the roof slab is inserted into the equipment penetration part of the roof slab. The vertical fins protruding from the roof slab and the vertical fins protruding from the outer peripheral wall of the device are set in advance in a separated state, and in this state, the device is inserted into the device 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 wall of the device penetration portion of the roof slab and the vertical fins projecting from the outer wall of the device come into contact with each other. Equipment installation method for roof slab in tank-type fast breeder reactor.