JPS6270794A - Pedestal for pressure vessel of nuclear reactor - Google Patents

Abstract

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

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a nuclear reactor pressure vessel pedestal that supports a nuclear reactor pressure vessel.

[Technical disadvantages of the invention and its problems]

FIG. 7 is a vertical sectional view showing the internal structure inside the reactor building of the boiling water reactor. Inside this reactor building 1, a reactor containment vessel 2 is installed. This reactor containment vessel 2 is
A dry well 3 is defined, and this dry well 3 has a structure in which it is communicated with a reactor I Moka suppression chamber 4 via a vent pipe 5.

Furthermore, a reactor pressure vessel pedestal (hereinafter simply referred to as a pedestal) is located within the dry well of the reactor containment vessel 2 and 3.

) 6 is erected, and a reactor pressure vessel 7 is supported on this pedestal 6. This pedestal 6 corresponds to the 6L structure shown in FIGS. 8 and 9.

Figure 8 is a cross-sectional view of the pedestal shown in Figure 7;
The figure is a partially enlarged view of the pedestal in Fig. 8. The pedestal 6 is constructed in a double cylindrical shape from an outer steel plate 8 and an inner steel plate 9, which are assembled into a cylindrical shape by connecting plate steel plates, and has an annular shape inside. A space is formed. The inner cylindrical steel plates 9 and the outer cylindrical steel plates 8 are arranged radially in plurality and reinforced with the bulges 10, so that the inner cylindrical steel plates 9 and the outer cylindrical steel plates 8 are arranged radially in plurality and reinforced with the tubes 10. It has a reinforced structure in which an annular space formed between the IjIJ4 plate 9 and the outer cylindrical steel plate 8 is filled with concrete 11.

The pedestal 6 configured in this manner works to support the reactor pressure vessel 7 not only during normal operation but also during an earthquake or a hypothetical accident. Therefore, pedestal 6
must be designed to be sufficiently rigid to withstand various loading conditions and combined loads.

However, since the thicknesses of the outer cylindrical steel plate 8I3 and the inner cylindrical steel plate 9 that extend into the pedestal 6 are limited, there is a limit to the strength improvement of the pedestal 6. To increase rigidity, steel plate 8,
However, in order to make the steel plates 8 and 9 thicker than a certain value, annealing is required because internal stress such as large residual strain remains at the joint between the steel plates. but,
If such annealing were to be performed, the equipment for annealing would be extremely large, the annealing work would take a long time, and the work would be complicated, making it virtually impossible. Therefore, it is necessary to select a plate thickness that does not require annealing. As a result, the outer cylindrical steel plate 8 and the inner cylindrical steel plate 9 are limited in thickness and strength, so when a large load is applied to the pedestal 6 during an earthquake, for example, the annular space between the steel plates 8 and 9 is There was a risk that the filled concrete 11 would be damaged.

In addition, since the steel plates 8 and 9 have excellent thermal conductivity, when the interior of the dry well 3 reaches a high temperature during a coolant loss accident, for example, there will be a large temperature difference between the center of the concrete 11 and its inner and outer peripheries. Therefore, there was a risk that the concrete 11 would be damaged due to the difference in thermal expansion. FIG. 10 is a schematic diagram of heat conduction at this time, and A shows the warm melon distribution.

(Object of the Invention) The present invention has been made in consideration of the above-mentioned circumstances, and is a nuclear reactor that suppresses the thickness of the steel plate within a limited range, increases the rigidity of the pedestal, and thereby improves the reliability of the pedestal. The purpose is to provide a pressure vessel pedestal.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention provides a reactor pressure vessel pedestal in which an annular space formed between an outer cylinder steel plate and an inner cylinder steel plate is filled with concrete. The invention is characterized in that at least one of the steel plates has a double-tube structure made of an outer steel plate and an inner steel plate, and a heat insulating area is formed in the space between the inner steel plate and the outer steel plate.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

1 is a longitudinal cross-sectional view of a pedestal according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of the pedestal, and FIG. 3 is a partially enlarged view of the pedestal of FIG. 2.

The basic differences between this pedestal 6 and the conventional one are as follows:
This is the structure of the inner cylindrical steel plate 9 and the outer cylindrical steel plate 8 of the pedestal 6, and the other configurations are the same as the conventional one, so the same reference numerals are given and the explanation will be omitted. The inner cylinder steel plate 9 is an inner cylinder inner steel plate 9a.
It has a two-part structure consisting of the inner cylinder outer steel plate 9b, and an annular space 12 is formed therebetween. Also, pedestal 6
The outer cylinder steel plate 8 also includes an outer cylinder inner steel plate 8a and an outer cylinder outer steel plate 8b.
It has a double cylinder structure, with an annular space 13 between.
is formed. In this pedestal 6, as shown in FIGS. 2 and 3, each steel plate 8B, 3b, 9a, g
A plurality of b are arranged radially or reinforced with b 10,
Concrete 11 is filled between the inner cylinder outer steel plate 9b and the outer cylinder inner steel plate 8a. In addition, the annular hollow IJ12 between the inner peripheral inner steel plate 9a and the inner cylinder outer steel plate 9b and the outer cylinder inner steel plate 8a
An annular space 13 between the outer cylinder outer steel plate 8b and the outer cylinder outer steel plate 8b is filled with air, and these annular spaces 12 and 13 are formed as a heat insulating area.

Next, the effect will be explained.

Each steel plate 8a, 8b, 9a of this pedestal 6.

9b supports the load acting on the pedestal 6 and moves to reduce the load applied to the concrete 11. Also,
For example, when the inside of the dry well 3 becomes high temperature due to the loss of cold JJI material, the annular space 12.13 suppresses the temperature rise of the concrete 1 to 11, and the central part of the concrete 11 and its inner and outer peripheries. Plow to reduce the temperature difference between the two parts. Figure 4 is a schematic diagram of heat conduction at this time, and 8
shows the temperature distribution.

According to the pedestal 6 having such a configuration and action,
The rigidity of the pedestal 6 is increased, and the seismic load on the reactor pressure horn vessel 7 and other reactor structures can be reduced, and the earthquake resistance can therefore be improved. Also,
In the event of a coolant loss accident, etc., the temperature rise of the concrete 11 can be suppressed, and the temperature difference between the central part of the concrete 11 and its inner and outer peripheral parts is alleviated. As a result, the reliability of the pedestal 6 is improved.

FIG. 5 is a partial cross-sectional view of a pedestal according to a second embodiment of the invention.

This pedestal 6 is different from the pedestal of the first embodiment in that there is an annular space 12 between the inner cylinder inner steel plate 9a and the inner cylinder outer steel plate 9b, and an annular space 13 between the outer cylinder inner steel plate 8a and the outer cylinder outer steel plate 8b. 14.1 Insulating material such as insulating concrete
5 is filled.

According to this pedestal 6, it is possible to achieve the same effect as in the first embodiment, and since the annular space 12.13 is filled with heat insulating elements U14 and 15, the heat insulating effect can be further enhanced. can.

FIG. 6 is a longitudinal sectional view of a pedestal according to a third embodiment of the present invention.

This pedestal 6 is different from that of the first embodiment as follows:
Cooling water is forced to circulate in the annular spaces 12 and 13. That is, this pedestal 6 is equipped with forced water cooling equipment 16. The forced water cooling equipment 16 includes a pipe 17 for supplying fresh water to the space 12.13, and a heat exchanger 18 interposed in the middle of the pipe 17. As the heat exchanger 18, for example, a cold n1 water type heat exchanger is used as an emergency supplement.

According to this pedestal 6, it is possible to obtain the same effect as in the first embodiment, and since fresh water is circulated within the space 12.13, the temperature of the concrete 1-11 is further regulated. , it is possible to achieve positive cooling uI, and the temperature difference between the central part of the concrete 11 and its inner and outer peripheral parts is further alleviated.

Note that the present invention is not limited to the illustrated embodiment and can be modified in various ways. For example, forced water cooling equipment 1 of the third embodiment
6 may be replaced by a forced air cooling facility that circulates air into the space 12.13.

Further, in the illustrated embodiment, the inner cylinder steel plate 9 and the outer cylinder steel plate 8
Both inner steel plates 8a, 9a and outer steel plates 8b, 9
It consists of inner cylinder steel plate 9 and outer cylinder steel plate 8.
Only one of them may be configured in this way.

〔Effect of the invention〕

As explained in detail above, according to the present invention, the inner cylinder steel plate J
At least one of the inner steel plate and the outer steel plate is constructed with a double cylinder structure, and a heat insulating area is formed in the space formed between the inner steel plate and the outer steel plate. Rigidity is increased, earthquake resistance can be improved, and reliability can be improved.

[Brief explanation of drawings]

1 is a longitudinal cross-sectional view of a pedestal according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of the pedestal in FIG. 1 taken along the line ■-ff, and FIG. 3 is a cross-sectional view of the pedestal in FIG. Partial enlarged view,
FIG. 4 is a schematic diagram of heat conduction of the pedestal of FIG. 1, FIG. 5 is a partial cross-sectional view of the pedestal according to the second embodiment of the present invention, and FIG. 6 is a diagram of the third embodiment of the present invention. Longitudinal section of the pedestal [Figure +i, Figure 7 is a vertical cross-sectional view of the reactor building, Figure 8 is a cross-sectional view of a conventional pedestal, Figure 9 is a partially enlarged view of the pedestal in Figure 8, Figure 10 is a FIG. 8 is a schematic diagram of heat conduction of the pedestal in FIG. 8; 6...Pedestal, 8...Outer f14M board, 8a...
- Outer station inner steel plate, 8b... Outer cylinder outer steel plate, 9... Inner cylinder steel plate, 9a... Inner cylinder inner steel plate, 9b... Inner cylinder outer steel plate, 10... Rib, 11...・Concrete, 12
．． 13... Space. Representative Patent Attorney Nori Chika Ken Shu
Hirofumi Mitsumata $ / Times $ 4 Figure 2 Figure q I $ 3 Figure 7 Figure 1O Figure

Claims (1)

[Claims] 1. In a reactor pressure vessel pedestal in which an annular space formed between an outer cylinder steel plate and an inner cylinder steel plate is filled with concrete, at least one of the inner cylinder steel plate and the outer cylinder steel plate is , consists of a double cylinder structure from an outer steel plate and an inner steel plate,
A nuclear reactor pressure vessel pedestal, characterized in that a heat insulating area is formed in a space between the inner steel plate and the outer steel plate. 2. The reactor pressure vessel pedestal according to claim 1, wherein the space between the inner steel plate and the outer steel plate is filled with a heat insulating material. 3. The reactor pressure vessel pedestal according to claim 1, characterized in that the space between the inner steel plate and the outer steel plate has a sealed structure, and is equipped with forced water cooling equipment for supplying and discharging fresh water to this space.