JP7699080B2 - Reactor containment vessel - Google Patents

Description

The present invention relates to a nuclear reactor containment vessel having an SC structure.

For the next generation of nuclear reactors, the use of SC containment vessels (SCCVs), which use an SC structure that combines steel plates and concrete with studs for the reactor containment vessel, is seen as promising from the perspective of reducing on-site construction labor and shortening construction time.

The objective of Patent Document 1 is to provide a reactor containment vessel that can improve workability during construction and reduce the occurrence of cracks and breaks in the inner steel plates even in the event of an accident, thereby ensuring safety.
Specifically, in the containment vessel of Patent Document 1, a concrete layer is sandwiched between an inner steel plate and an outer steel plate, and a groove is formed in the inner steel plate. The groove deforms to relieve thermal strain occurring in the inner steel plate, thereby preventing cracks and fractures occurring in the inner steel plate and the concrete.

JP 2001-281379 A

In the case of an SCCV, the temperature conditions during an accident are severe (around 200°C), and there is a possibility that the steel plate inside the upper dry well section will buckle due to the thrust force of the steel plate. This poses the challenges of narrowing the stud pitch, needing to use stronger steel plates, and needing a steam vent mechanism to prevent the inner steel plate from buckling due to the back pressure of steam from the concrete layer between the inner and outer steel plates.

In the reactor containment vessel of Patent Document 1, as described above, the grooves are formed in the inner steel plate, thereby making it possible to reduce thermal strain occurring in the inner steel plate.
However, in the reactor containment vessel of Patent Document 1, the space between the inner steel plate in which the groove is formed and the concrete layer is a closed space, so that the steam back pressure from the concrete layer cannot be released, and there is a risk that buckling will occur in the inner steel plate due to the steam back pressure.

To solve the above problems, the present invention provides a reactor containment vessel that can prevent buckling of the inner steel plate due to steam back pressure from the concrete layer between the inner and outer steel plates.

The above and other objects of the present invention, as well as the novel features of the present invention, will be made clear by the description in this specification and the accompanying drawings.

The reactor containment vessel of the present invention is a reactor containment vessel comprising a first layer made of steel plates, a second layer provided outside the first layer and made of concrete, and a third layer provided outside the second layer and made of steel plates.
In the reactor containment vessel of the present invention, a space with an open top exists between the first layer in the portion that contacts the upper dry well inside the reactor containment vessel and the second layer, and the first layer in the portion that contacts the upper dry well is separated from the second layer due to the existence of the space and is not in contact with the second layer, while the first layer in the portion other than the portion that contacts the upper dry well is in contact with the second layer.

According to the reactor containment vessel of the present invention described above, a space with an open top exists between the first layer in contact with the upper dry well and the second layer, so the back pressure of steam from the concrete of the second layer can be released from the space. This makes it possible to prevent the buckling of the inner steel plate due to the back pressure of steam.

Note that issues, configurations, and advantages other than those described above will become clear from the explanation of the embodiments below.

FIG. 2 is a schematic cross-sectional view of a reactor containment vessel according to the first embodiment. FIG. 2 is an enlarged cross-sectional view of a main portion of FIG. 1 . FIG. 11 is an enlarged cross-sectional view of a main part of a reactor containment vessel according to a second embodiment.

The following describes the embodiments and examples of the present invention using text and drawings. However, the structures, materials, and various other specific configurations shown in the present invention are not limited to the embodiments and examples discussed here, and can be combined or improved as appropriate without changing the gist of the invention. Also, elements that are not directly related to the present invention are not shown in the figures.

The reactor containment vessel of the present invention is a reactor containment vessel that includes a first layer made of steel plates, a second layer that is disposed outside the first layer and made of concrete, and a third layer that is disposed outside the second layer and made of steel plates. In other words, the reactor containment vessel of the present invention has the aforementioned SC structure that is made of steel plates, concrete, and steel plates.

The reactor containment vessel of the present invention has a space with an open top between the first layer, which is in contact with the upper dry well inside the reactor containment vessel, and the second layer.

According to the configuration of the reactor containment vessel of the present invention, a space with an open top exists between the first layer in contact with the upper dry well and the second layer, so the back pressure of steam from the concrete of the second layer can be released from the space. This makes it possible to prevent the buckling of the inner steel plate due to the back pressure of steam.

In the above-mentioned reactor containment vessel, a sand cushion may be connected to the outside of the first layer below the space, and a drain pipe extending to the outside of the reactor containment vessel may be connected to the sand cushion.
In this configuration, the steel plate of the first layer is cooled from the outside with cooling water, and the used cooling water can be discharged to the outside of the reactor containment vessel through the sand cushion and the drain pipe.

In the above-mentioned reactor containment vessel, a configuration may be adopted in which CT steel or FB steel is arranged on the outside of the first layer to reinforce the steel plate of the first layer.
In this configuration, the steel plate of the first layer can be reinforced by the CT steel or FB steel arranged on the outside of the first layer, thereby improving earthquake resistance.

In the above-mentioned reactor containment vessel, the space may be configured to communicate with a cooling pool that is provided above the upper dry well and that contains cooling water.
In this configuration, the steel plate of the first layer can be cooled by flowing cooling water from the cooling pool into the space.

In the above-mentioned configuration, a connection part that can be opened and closed may be provided between the cooling pool and the space part.
In the case of this configuration, by controlling the opening and closing of the connection portion, it is possible to adjust the flow rate of cooling water flowing through the space portion and whether or not the steel plate of the first layer is cooled by the cooling water.

Next, we will explain a specific example of a reactor containment vessel.

Example 1
A reactor containment vessel according to a first embodiment will be described below with reference to FIGS.
Fig. 1 is a schematic cross-sectional view of a reactor containment vessel of Example 1. Fig. 1 shows a schematic cross-sectional view of a reactor building including a reactor containment vessel 3.
FIG. 2 is an enlarged cross-sectional view of a main portion of FIG.

1, the reactor containment vessel 3 of this embodiment has a reactor pressure vessel 2 therein containing a reactor core 1, and has a three-layer structure consisting of an inner first layer of inner steel plate 11, a middle second layer of concrete 12, and an outer third layer of outer steel plate 13. That is, this reactor containment vessel 3 has the above-mentioned SC structure.
Although not shown, the inner steel plate 11 of the first layer and the outer steel plate 13 of the third layer are each formed in a cylindrical shape.

The area between the reactor pressure vessel 2 and the reactor containment vessel 3 is divided into a lower suppression pool 4 and an upper dry well 5, and the suppression pool 4 and the upper dry well 5 are isolated by a diaphragm floor 6 provided between them.
Cooling water 7 is contained in the bottom of the suppression pool 4 .

Cooling pools 8, 9, and 10 containing water are provided further above the upper dry well 5. Adjacent cooling pools 8, 9, and 10 are separated by concrete.
The cooling pools 8, 9, and 10 are used, for example, as suppression pools, spent fuel pools, temporary equipment storage pools, and the like.

As shown in Figures 1 and 2, the reactor containment vessel 3 of this embodiment has a space 14 between the inner steel plate 11 of the first layer in the portion in contact with the upper dry well 5 and the concrete 12 of the second layer.
2, the space 14 has a substantially uniform thickness, and at the upper part, the space 14 becomes thicker as it goes up due to the reduction in the diameter of the reactor containment vessel 3. Moreover, unlike the closed space of the configuration of Patent Document 1, the space 14 has an open upper part.

In addition, in the portion of the reactor containment vessel 3 that contacts the suppression pool 4 other than the portion that contacts the upper dry well 5, the first layer of inner steel plate 11 and the second layer of concrete 12 are in contact with each other without providing a space.
As shown in Figures 1 and 2, the first layer inner steel plate 11 is an integral steel plate in which the portion in contact with the upper dry well 5 and the portion in contact with the suppression pool 4 are continuously formed.

Furthermore, in this embodiment, a connection part 15 is provided that penetrates the concrete below the cooling pool 9 above the upper dry well 5 and connects the cooling pool 9 to the space 14. This connection part 15 is configured to be able to open and close a valve or the like. This connection part 15 connects the cooling pool 9 to the space 14.

By opening the connection 15, the water in the cooling pool 9 can be made to flow along the inner steel plate 11 into the space 14 as shown by the arrow W, and the inner steel plate 11 can be cooled by this water W. In this way, in the event of an accident, the inner steel plate 11 can be cooled by flowing water from the cooling pool 9.
In addition, by controlling the opening and closing of the connection portion 15, the flow rate of the water W flowing into the space portion 14 and whether or not the water W cools the inner steel plate 11 of the first layer can be adjusted.
In order to drain the water that has flowed into the space 14, it is preferable to provide a drain outlet in the space 14 at a location not shown.

In addition, by flowing water W into the space 14, it is possible to cool and seal the so-called penetration portion, where a pipe (not shown) penetrates the reactor containment vessel 3 (such as the inner steel plate 11) above the diaphragm floor 6.

According to this embodiment, since the space 14 is provided between the inner steel plate 11 and the concrete 12, the inner steel plate 11 is independent from the concrete 12. As a result, even if the inner steel plate 11 is exposed to a high temperature of about 200° C. in the upper dry well, it is possible to freely deform the inner steel plate 11 in response to thermal distortion, and therefore it is possible to prevent the inner steel plate 11 from buckling due to thermal deformation.
Furthermore, in this embodiment, there is no need to process the inner steel plate 11 into a groove as in the configuration of Patent Document 1, so the manufacturing cost of the inner steel plate 11 can be reduced compared to the configuration of Patent Document 1 in which a groove is provided in the inner steel plate.

Furthermore, according to this embodiment, a space 14 is provided between the inner steel plate 11 and the concrete 12, so that the back pressure of steam from the concrete 12 does not act directly on the inner steel plate 11, thereby preventing buckling of the inner steel plate 11 due to the back pressure of steam.
In particular, since the space 14 is wider and open at the top, unlike the closed space of the configuration of Patent Document 1, the back pressure of steam from the concrete 12 can be released to the top.

In addition, according to this embodiment, the cooling pool 9, which is provided above the upper dry well 5 and contains cooling water, is connected to the space 14 via the connection 15, so that the water W from the cooling water pool 9 can be made to flow through the connection 15 into the space 14 to cool the inner steel plate 11.

The above-mentioned effects can be obtained, and according to this embodiment, a nuclear containment vessel 3 that is equipped with heat resistance, pressure resistance, and cooling performance can be provided.

Example 2
Second Embodiment Next, a reactor containment vessel according to a second embodiment will be described.
FIG. 3 is an enlarged cross-sectional view of a main portion of a reactor containment vessel according to the second embodiment.
In FIG. 3, the same components as those in the reactor containment vessel 3 of the first embodiment are denoted by the same reference numerals.

As shown in FIG. 3 , in the reactor containment vessel 3 of this embodiment, a sand cushion 18 is provided under the space 14 in order to drain the water W that has flowed into the space 14, and a drain pipe 19 extends from the sand cushion 18 to the outside of the reactor containment vessel 3.
2, the space 14 has a substantially uniform thickness in the area shown in the enlarged cross-sectional view of FIG. 2.
The other configurations are similar to those of the first embodiment shown in FIGS. 1 and 2, so duplicated explanations will be omitted.

According to this embodiment, similarly to the first embodiment, in the portion facing the upper dry well 5, a space 14 is provided between the inner steel plate 11 and the concrete 12, and the space 14 is connected to the cooling pool 9 shown in FIG. 1 via a connection portion 15.
As a result, according to this embodiment, like the first embodiment, it is possible to provide a nuclear containment vessel 3 that is equipped with all of the heat resistance, pressure resistance, and cooling capabilities.

In addition, according to this embodiment, a sand cushion 18 is provided under the space 14, and a drain pipe 19 extends from the sand cushion 18 to the outside of the reactor containment vessel 3, so that water that has entered the space 14 can be easily discharged through the sand cushion 18 and the drain pipe 19.

(Modification)
As a modification of the above-described embodiment, a configuration can be adopted in which CT steel or FB steel is provided on the outside of the inner steel plate of the first layer to reinforce the inner steel plate.
In this configuration, a space is provided between the CT steel or FB steel provided on the outside of the inner steel plate of the first layer and the concrete of the second layer.
The CT steel or the FB steel may be in contact with the inner steel plate, or may have a space between the CT steel or the FB steel and the inner steel plate.
By reinforcing the outside of the inner steel plate with CT steel or FB steel, the earthquake resistance of the containment vessel can be improved.

In addition, in Examples 1 and 2, the thickness of the space 14 is approximately uniform in the range of the enlarged cross-sectional views of Figures 2 and 3, but the thickness of the space is not limited to being approximately uniform.
For example, it is possible to adopt a configuration in which the boundary surface between the space and the concrete is inclined so that the upper part is thicker and the lower part is thinner. In this configuration, the upper part of the space is thicker, so that steam can easily escape. In addition, since the boundary surface is inclined, it does not hinder the flow of cooling water, as in the configurations of Examples 1 and 2 in which the boundary surface is a surface perpendicular to the horizontal surface.

As another modification of the above embodiment, instead of the configuration in which the water W flows into the space 14 through the cooling pool 9 and the connection part 15, it is also possible to employ a configuration in which the water flows into the space by another configuration. For example, it is also possible to supply water to the space through a water supply pipe from another cooling pool or water supply equipment.
When the configuration in which the water W flows into the space 14 through the cooling pool 9 and the connection portion 15 is adopted as in the above-described embodiment, there is an advantage in that the speed and flow rate of the water W can be increased.

The present invention is not limited to the above-described embodiments and examples, but includes various modifications. For example, the above-described embodiments and examples have been described in detail to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all of the configurations described.

1...core, 2...reactor pressure vessel, 3...reactor containment vessel, 4...suppression pool, 5...upper dry well, 6...diaphragm floor, 7...cooling water, 8, 9, 10...cooling pool, 11...inner steel plate, 12...concrete, 13...outer steel plate, 14...space, 15...connection, 18...sand cushion, 19...drain pipe, W...water

Claims (5)

A first layer made of a steel plate;
a second layer provided outside the first layer and made of concrete;
A reactor containment vessel comprising: a third layer provided outside the second layer and made of a steel plate;
a space portion with an open upper portion is present between the first layer and the second layer in a portion in contact with an upper dry well inside the reactor containment vessel,
The first layer in a portion in contact with the upper dry well is separated from the second layer by the existence of the space portion, and is not in contact with the second layer;
The first layer is in contact with the second layer except for the portion in contact with the upper dry well.
Reactor containment vessel. The reactor containment vessel of claim 1, in which a sand cushion is connected below the space, and a drain pipe extending to the outside of the reactor containment vessel is connected to the sand cushion. 2. The reactor containment vessel according to claim 1, wherein the third layer is in contact with the second layer, and the first layer, the second layer, and the third layer are integrated together in portions other than a portion in contact with the upper dry well. The reactor containment vessel according to claim 1, wherein the space is connected to a cooling pool that is provided above the upper dry well and contains cooling water. The reactor containment vessel according to claim 4, wherein an openable and closable connection is provided between the cooling pool and the space.

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