JPH0133797B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat insulating structure for a nuclear reactor bulkhead.

Generally, the reactor structure of a tank-type liquid metal cooled fast breeder reactor (LMFBR) is as shown in the schematic diagram of FIG. 1. That is, in the figure, a reactor vessel 1 is attached to a roof slab 2, and a reactor core 3 is supported by a core support structure 4 attached to the reactor vessel 1.

Further, 5 is a horizontal bulkhead, 6 is a vertical bulkhead, on which are installed a core upper mechanism 7, a pump 8, and an intermediate heat exchanger 9, an upper plenum 10, an intermediate plenum 1
1, a lower plenum 12, and other regions are formed. Here, the horizontal partition wall 5 and the vertical partition wall 6 partition the upper plenum 10 and the intermediate plenum 11, and suppress the transfer of heat from the high temperature upper plenum 10 to the lower temperature plenum 12 via the low temperature intermediate plenum 11. The horizontal partition wall 5 and the vertical partition wall 6 are provided with a predetermined heat insulating structure as necessary.

FIG. 2 is a sectional view showing a conventional heat insulating structure, in which a large number of stainless steel plates 13 are stacked at appropriate intervals with spacers 14 and attached to an annular support plate 16 with bolts 15. It is installed so as to partition between the high-temperature upper plenum region 10 and the low-temperature middle plenum region 11, and the heat transfer between these regions is suppressed by the above-mentioned heat insulating structure.

The core tank 1 surrounding the core support structure 4 and the high pressure plenum 18 is designed to substantially block the flow of coolant between the intermediate plenum 11 and the lower plenum 12.
The heat passing through the horizontal partition wall 5 and the vertical partition wall 6 passes through the intermediate plenum 11 and is transmitted to the lower plenum 12. The pump 8 then sucks the coolant from the lower plenum 12 and passes it through the pipe 8a to the high pressure plenum 1.
Discharge at 8. Coolant entering high pressure plenum 18 is heated through core 3 and rises to upper plenum 10 . The high-temperature coolant in the upper plenum 10 is sucked into the intermediate heat exchanger 9, undergoes heat exchange, becomes lower temperature, and is discharged to the lower plenum.

However, a coolant such as sodium is filled between the members of the heat insulating structure. Sodium has high thermal conductivity, and on the other hand, stainless steel plate 13 with an insulating structure
Since stainless steel has a thermal conductivity that is about 1/3 to 1/4 that of sodium, the heat shielding efficiency is not large. It is necessary to significantly increase the thickness and number of sheets, which not only has a large impact on the quantity of materials, but also increases costs and poses problems in terms of earthquake resistance.

Also, due to the temperature distribution that occurs inside the heat insulating structure, the laminate deforms into an arched shape, which causes the bolt 15 to deform.
There are problems such as the risk of damage due to the application of excessive force.

Therefore, in order to solve the above-mentioned problems, from the viewpoint of cost and earthquake resistance, we developed a
Moreover, there has been a desire to develop an effective heat insulating structure that is relatively easy to manufacture and install, and is equipped with a support structure that can appropriately absorb the thermal deformation that occurs in the heat insulating structure.

The present invention has been made in response to the above-mentioned demands.The present invention has been made to create a heat insulating structure by stacking a large number of stainless steel cylindrical bodies, each of which has a vacuum inside or is filled with an inert gas. The present invention provides a heat insulating structure for a nuclear reactor bulkhead in which a bulkhead and a vertical bulkhead suppress the transfer of heat from an upper plenum to a lower plenum via an intermediate plenum.

Embodiments according to the present invention will be described below with reference to FIGS. 3 to 5.
This will be explained in detail with reference to the drawings.

FIG. 3 shows a stainless steel cylindrical body 20 according to the present invention.
This is a cross-sectional view of , the inside of which is evacuated or filled with an inert gas such as argon gas, both ends of which are sealed, and which are molded to any desired length and thickness.

Figures 4a to 4d are conceptual diagrams showing installation examples of the heat insulating structure according to the present invention, and Figures 4a and b are horizontal FIG. 4a is a plan view of the partition wall 5, and in particular, FIG. 4a is an example in which the cylindrical bodies 20 according to the present invention shown in FIG. , the length of straight pipes is gradually extended and a large number of them are stacked on top of each other.
It has a structure in which a large number of 0's are formed and arranged in a ring or coil shape and stacked on top of each other.

Furthermore, FIGS. 4C and 4D are perspective views of the vertical partition wall 6 installed to suppress heat transfer in the radial direction of the nuclear reactor shown in FIG. The upper plenum 10 and the intermediate plenum 11 are separated from each other by the support plate 16 and the vertical plate 6a, and the upper edge thereof is continuous with the inner edge 16a of the support plate. . FIG. 4c shows an example in which the cylindrical body 20 is installed in the vertical direction, and FIG. 4d shows an example in which the cylindrical body 20 is installed in the horizontal direction. In the example of FIG. 4d above,
The cylindrical body 20 is constructed by arranging relatively short straight pipes along the circumferential direction as shown in FIG.
It is also possible to form and arrange it into a ring shape or a coil shape as shown in FIG. b.

On the other hand, FIG. 5 is a detailed view of the section taken along arrow A-A in FIGS.
is the low temperature intermediate plenum.

Heat transfer between the high-temperature upper plenum 10 and the low-temperature middle plenum 11 is suppressed by the cylindrical body 20, and when a large number of the cylindrical bodies 20 are stacked, there is a large gap in the area. Filling efficiency is increased by using the thin cylindrical body 20a.

Further, the cylindrical bodies 20 and 20a are connected to the support plate 2.
1, the blocks are divided by partition plates 22 and stacked on top of each other.

The cylindrical bodies 20 and 20a are each separated by a partition plate 22 and held between a support plate 21 and a presser plate 23, and the presser plate 23 is a plate attached to a beam 25 bolted to the partition plate 22. Spring
The cylindrical bodies 20 and 20a are held in a properly stacked state by being pressed down by a spring body 24 such as a coil spring.

Note that the bolted portion of the beam 25 is connected to the support plate 2.
It has a hole structure so that the difference in thermal expansion between the beam 1 and the beam 25 can be absorbed.

Further, by appropriately selecting the diameter and plate thickness of the cylindrical body, it is possible to prevent the cylindrical body from floating up even without being pressed from above by the press plate 23 and the spring body 24. Furthermore, although the partition plates 22 are provided at appropriate intervals, the cylinder groups and the partition plates 22 are
The mounting intervals of the partition plates 22 are set so that the partition plates 22 are not installed in a completely close contact state but with a slight gap between them.

As explained in detail above, the heat insulating structure of the nuclear reactor according to the present invention is a simple structure consisting of a stack of many cylindrical bodies whose interiors are evacuated or filled with an inert gas such as argon gas. , has the following effects.

Thermal resistance can be improved by increasing the proportion of gas with very low thermal conductivity or the vacuum area, reducing the proportion of sodium with high thermal conductivity, and cutting off heat transfer channels at various places. It's increasing.

It is relatively lightweight and can have a compact structure. For example, compared to a conventional structure made of laminated stainless steel plates, the amount of material required is about 1/10 or less to achieve the same insulation performance.

Even if a problem were to occur in some of the cylindrical bodies and sodium entered the interior, the effect on the overall function of the insulation structure would be minimal. Furthermore, since the stress of the heat insulating structure itself can be reduced, reliability regarding structural soundness is high.

Heat transfer from the hot upper plenum through the cooler middle plenum to the lower plenum is reduced;
Improves thermal efficiency.

[Brief explanation of drawings]

Fig. 1 is a schematic block diagram showing the reactor structure of a tank-type LMFBR, Fig. 2 is a plan view of a heat insulating structure showing a conventional embodiment, and Fig. 3 is a cross section of a stainless steel cylindrical body showing an embodiment according to the present invention. Figures 4a to 4d are conceptual diagrams showing installation examples of the heat insulating structure according to the present invention.
The figure is a detailed view of the section taken along the line A-A in FIGS. 4a and 4b. DESCRIPTION OF SYMBOLS 1...Reactor vessel, 5...Horizontal bulkhead, 6...Vertical bulkhead, 6a...Vertical plate, 10...Upper plenum, 11...Middle plenum, 12...Lower plenum, 16...Support plate, 16a ... Common-law, 17...
Core tank, 20...Cylindrical body, 21...Support plate, 22
... Partition plate, 23 ... Pressing plate, 24 ... Spring body,
25...beam.

Claims (1)

[Claims] 1. In a tank-type liquid metal cooled fast breeder reactor,
A horizontal structure that suppresses vertical heat transfer by stacking a number of cylindrical bodies with a vacuum inside or filled with inert gas on an annular support plate installed at the boundary between the upper and middle plenums. A vertical partition wall in which a large number of the cylindrical bodies are stacked along a vertical plate provided at the upper end of the core tank housing the reactor core and whose upper edge is continuous with the inner edge of the support plate to suppress heat transfer in the semi-longitudinal direction. An insulating structure for a nuclear reactor bulkhead, characterized by comprising: