JP2000121771A - Water utilized reactor with receptacle accommodating variable inner structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactor that cannot be damaged by steam explosion even if it occurs. SOLUTION: A water utilized reactor with a vessel 10 and a reactor core 12 is provided with a receptacle 20 in the shape of a washbowl that is accommodated at the lower portion of the core 12 in the vessel 10 and at the same time is formed by a fireproof material 24 at least partially. The receptacle 20 can receive corium that is formed in the case of accidental melting of the core 12 and is provided with variable inner structure 38 at least near the inner surface of the receptacle 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
pressurized water or boiling water, such that the vessel has a basin-shaped receptacle intended to receive solid or liquid pieces derived from the reactor core upon accidental melting of the reactor core. Related to nuclear reactors.

[0002]

BACKGROUND OF THE INVENTION With respect to nuclear reactors, a number of systems have been devised and developed in the last 20 to 30 years with the aim of limiting the consequences of causing partial or complete melting of the reactor core. ing.

In particular, French Patent Application Publication No. 234
As disclosed in US Pat. No. 1,181, a suppression device that can be placed at the bottom of a reactor vessel has already been proposed. Such suppression devices are intended to prevent perforation of the vessel by corium formed during accidental melting of the reactor core. The restraining device comprises a plurality of spaced apart horizontal plates fixed below the core to the vessel wall. Openings are formed in these plates in a zigzag manner between the plates, and the edges of the plates are bent upward. In an accident, the corium falls by gravity, passes through an opening in the plate, rides over a bell-shaped disperser located in the center of the horizontal plate, and stays at the bottom of the vessel.

[0004] Particularly, in the case of a reactor cooled by a liquid metal, as disclosed in US Pat. No. 3,964,966, a core is provided below a reactor core inside a reactor vessel. It has already been proposed to arrange a lium receptacle. This receptacle is directly suspended by the lower horizontal plate supporting the core. A heat exchange pipe projects upward from the bottom of the receptacle into the interior of the receptacle. These pipes are closed at the upper end and communicate with the inside of the receptacle through a hole provided near the upper end.

[0005]

Regardless of the geometry of the receptacle device that is supposed to be incorporated inside the vessel of a water reactor, there is very little risk that an accidental core melting can cause an explosion. It is present, albeit slightly. As the corium flows toward the bottom of the vessel, it breaks up (splits) into small particles. The water contained in the reactor vessel evaporates upon contact with small corium particles. A vapor film is formed around each particle. This creates favorable conditions for the explosion causing a high energy shock wave. Due to the origin of this type of explosion, it is commonly referred to as a "steam explosion".

[0006] Currently, receptacle devices for receiving and holding corium at the bottom of a water reactor vessel are not protected from such steam explosions. Despite the low probability of an interaction between water vapor and corium, the possibility of this type of explosion
It cannot be completely erased. The extremely strong pressure peak created by the explosion compromises the integrity of the receptacle device and thus the effectiveness of the receptacle device.

[0007]

The subject of the present invention is precisely a pressurized water or boiling water reactor in which a corium receiving device is provided in a vessel, due to the unique construction of the corium receiving device. In addition, the receiving device can be protected from the effects of a possible steam explosion, thus maintaining the integrity of the receiving device in the event of an accident.

According to the present invention, the result is a water-based reactor comprising a vessel and a reactor core housed in the vessel, wherein the reactor is housed below the core in the vessel. And a basin-shaped receptacle formed at least in part from a refractory material, the receptacle capable of receiving corium formed upon accidental melting of the core, wherein the receptacle comprises at least an inner surface of the receptacle. It is obtained by a nuclear reactor characterized by being provided with a deformable internal structure in the vicinity.

In the reactor configured as described above,
Corium formed when the core melts breaks up (splits into fragments) as it enters the receptacle. When a steam explosion occurs, the energy released by the explosion is dissipated at the point of occurrence by the deformable internal structure contained within the receptacle. Thus, the integrity of the receptacle (being undamaged) is maintained, and the entire amount of corium flowing out of the core during melting can be received by the receptacle.

[0010] Also, a large amount of hot corium can cause partial melting of the internal structure contained in the receptacle. In this case, a material such as iron mixes with the corium and contributes to a gradual decrease in the temperature of the corium. In this way, the risk of receptacle damage due to melting of the refractory material is limited.

[0011] Preferably, the deformable internal structure is a metal structure configured to allow water circulation within the structure. This configuration contributes to a decrease in the temperature of the corium and the receptacle during an accident.

[0012] Although additionally and preferably, the receptacle may comprise a container, for example a spherical container, preferably containing a material such as a silica-based material. When the container breaks, the corium comes into contact with this material, forming a chemical mixture that reduces the corium temperature.

[0013] In a first embodiment of the invention, the deformable internal structure comprises a grid structure comprising a plurality of intersecting bars disposed on the inner surface of the receptacle.

In this case, a plurality of cross bars forming a lattice structure can be filled over most of the receptacle. Alternatively, a structure made of a perforated metal sheet forming a plurality of compartments can be provided inside the lattice structure. In the former case, for example, a container filled with a silica-based material can be accommodated between the cross bars. In the latter case, the container is preferably housed in a compartment of the plurality of compartments that is located at least closest to the grid structure of the plurality of cross bars.

In a second embodiment of the present invention, the deformable internal structure includes a plurality of metal sheets that are substantially parallel to the inner surface of the receptacle and are spaced apart from each other. And a counter brace connecting the two.

In one variation of this second embodiment of the present invention, the metal sheet and the counterbrace form a plurality of modules that are oriented substantially parallel to the interior surface of the receptacle. Housing a plurality of tubes. In this case, these tubes function as containers filled with, for example, a silica-based material.

In a third embodiment of the present invention, the deformable internal structure has a honeycomb structure, and the partition walls of the honeycomb structure are substantially perpendicular to the inner surface of the receptacle.

In this case, the cells partitioned by the honeycomb structure can function as a container filled with, for example, a silica-based material.

In a fourth embodiment of the present invention, the deformable internal structure comprises a central collector disposed in a plurality of continuous layers substantially parallel to the interior surface of the receptacle and located at the bottom of the receptacle. A plurality of tubes communicating with the plurality of tubes.

Advantageously, a perforated distribution plate which functions to spread the corium flowing into the receptacle can be provided on the receptacle. The perforated distribution plate can be in the form of a cone, with the apex pointing downwards, in particular if the deformable internal structure is formed as a continuous layer in the receptacle.

Further, in order to improve the cooling performance of the receptacle at the time of the accident by the water circulation by natural convection, the receptacle is isolated from the bottom of the vessel by the space opened on the upper side.

[0022]

BRIEF DESCRIPTION OF THE DRAWINGS Various non-limiting exemplary embodiments of the present invention are described below with reference to the accompanying drawings.

FIG. 1 is a vertical sectional view showing the lower part of a water utilization type nuclear reactor. The vessel of the nuclear reactor includes a receptacle according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view similar to FIG.
A modification of the embodiment is shown. FIG. 3 is a sectional view similar to FIGS. 1 and 2, showing a second modification of the first embodiment of the present invention. FIG. 4 is a cross-sectional view similar to FIGS. 1-3, showing a second embodiment of the present invention. FIG. 5 is a cross-sectional view similar to FIGS. 1-4, showing a modification of the second embodiment of the present invention. FIG. 6 is a sectional view similar to FIGS. 1 to 5, showing a third embodiment of the present invention. FIG. 7 is a sectional view similar to FIGS. 1 to 6, showing a fourth embodiment of the invention.

Various embodiments of the present invention, all of which relate to pressurized water reactors, and variations thereof, will now be described. However, as already pointed out, the invention is not limited to this type of reactor, but generally relates to all other types of water-based reactors, in particular boiling water reactors It is.

The various embodiments and variants described below comprise a number of identical or similar components. These members are described with reference to FIG.
I will explain only once. In the case where it is necessary to refer to the description for clarity, the same members are denoted by the same reference numerals even in different drawings.

A first embodiment of the present invention will be described with reference to FIG.

In this figure, reference numeral 10 indicates a reactor vessel. More specifically, only the lower portion of the vessel is shown. The vessel 10 includes a reactor core 12 in a central portion, and includes internal equipment related to the core.

The core 12 is typically formed from a number of vertically arranged nuclear fuel assemblies. The nuclear fuel assembly rests on the lower horizontal plate 14. The plate 14 is perforated in the vicinity of each nuclear fuel assembly so that cooling water retained in the vessel 10 can circulate inside the nuclear fuel assembly. The perforated flow distribution plate 16 preferably has a convex lower portion and is fixed below the plate 14 over the entire plate 14.

The reactor core and associated internal equipment, such as, for example, the horizontal lower plate 14 and the perforated plate 16, are supported on the vertical cylindrical wall of the vessel 10 via support and guide devices 18.

It should be noted that within the scope of the present invention, the core 12 and associated internal equipment can be of any shape other than that shown.

In the present invention, as shown in FIG. 1, a basin-shaped receptacle 20 is arranged inside the vessel 10 below the reactor core 12. More specifically, the receptacle 20 includes a perforated plate 16,
It is located between the convex and generally hemispherical base of the vessel 10.

Receptacle 20 is configured to receive corium during accidental melting of reactor core 12. The term "corium" refers to the molten mass that would be produced during such an accident, and corium generally refers to nuclear fuel, nuclear fuel cladding,
It contains the coating for the control rods and the internal equipment associated with the core 12. The receptacle 20 includes the reactor core 12.
The arrangement and configuration is such that in the event of a serious accident that could lead to complete melting of the corium, all of the corium can be received.

Preferably, as shown in FIG. 1, the receptacle 20 is separated from the base of the vessel 10 by an amount corresponding to a space communicating with the gap between the upper outer peripheral edge of the receptacle and the vessel 10 on the upper side. , Are isolated. This space 22 allows for the circulation of water retained in the reactor vessel 10, as indicated by the illustrated arrows. In the event of an accident, the water circulation
Natural convection automatically occurs in this space 22. The effect provided by this water circulation is the cooling of the receptacle 20.

[0034] The receptacle 20 has at least one brick layer 24 formed of a refractory material. This material is selected so as to have a melting point as high as possible and to have good chemical compatibility with corium. The material can in particular be a ceramic material based on zirconium, which also has the advantage of being widely available in the industrial market.

As shown in FIG. 1, the brick 24
They are juxtaposed and preferably have complementary edge shapes. The edge shape may be U-shaped or a widened dovetail shape to allow interconnection with each other.

The receptacle 20 has a brick 2 inside.
4 is provided with a metal casing. This metal casing can in particular be formed from stainless steel. The metal casing has an inner skin 26 and an outer skin 28, and one or more layers of the brick 24 are completely covered between the inner skin 26 and the outer skin 28. The metal casing also includes an upper flange 30 for connecting the upper edges of each of the inner skin 26 and outer skin 28 of the receptacle 20 to each other.

The upper flange 30 can be used to suspend the receptacle 20 with respect to the vessel 10. In this case, as shown in FIG. 1, the receptacle 20 is supported on a support 32 provided inside the vessel 10.

As a modification, a radial reinforcing member (not shown) oriented radially with respect to the vertical axis of the vessel 10 is provided in the space 22 separating the receptacle 20 from the bottom of the vessel 10. Can be interposed. In this case, the radial reinforcing member is provided with a plurality of holes for assisting the circulation of water in the space 22.

In the embodiment shown in FIG. 1, the receptacle 20 has a substantially hemispherical shape concentric with the shape of the base of the vessel 10.

In a modification (not shown) of this embodiment, a substantially cylindrical portion having a center line on the vertical axis of the vessel 10 is connected to the hemispherical shape to extend the receptacle 20 upward. be able to. This configuration is employed especially when the total volume of corium that is expected to be formed in a serious accident is expected to exceed the available volume in the receptacle 20 if the hemispherical receptacle 20 is used. can do. The estimation of the volume available in the receptacle 20 is performed in consideration of the existence of a predetermined number of structures described below disposed inside the receptacle.

In order to effectively receive the entire amount of corium produced by the core 12 in a serious accident into the receptacle 20, a ring collector 34 is provided above the upper edge of the receptacle, as shown in FIG. Can be arranged. The ring collector 34 can be supported on the upper flange 30 of the receptacle 20 via, inter alia, a cross beam structure 36.

The upper surface of the ring collector 34 is in the shape of a hopper that is curved inward and faces upward near the wall of the vessel 10.
More specifically, a clearance limited to a few centimeters is provided between the collector 34 and the vessel 10 wall. This is to prevent the flow of the debris from the core at the time of melting from entering the space 22 between the receptacle 20 and the base of the vessel 10.

As an essential feature of the receptacle 20 of the present invention, a deformable internal structure (deformable internal structure) 38 is disposed at least near the inner surface of the receptacle formed by the inner skin 26. . The primary purpose of this deformable internal structure 38 is to prevent the possibility of a steam explosion inside the receptacle, if any, from causing damage to the receptacle. More specifically, the deformation of the deformable internal structure caused by the shock wave induced by the steam explosion causes the energy released by the explosion to be dissipated and / or attenuated. Thus, the receptacle 20, especially the refractory brick 24, is protected from shock waves due to the explosion.

In the first embodiment of the present invention, as shown in FIG.
A grid structure including a plurality of cross bars 40 is provided over a predetermined thickness on the inner skin 26 forming the inner surface of the inner skin. The plurality of crossbars 40 are welded together and to the inner skin 26 and are substantially parallel to the interior surface of the receptacle, for example, in a vertical plane and in a horizontal plane. The plurality of intersecting bars 40 form a metal grid structure, which forms a space between the bars to allow sufficient circulation of water. Lattice structure thickness,
The cross-sectional shape, interval, and orientation of the plurality of bars 40 forming the lattice structure are determined so as to absorb a desired amount of shock waves generated when a steam explosion occurs.

In the embodiment of FIG.
The metal skin 42 is lined with the lattice structure consisting of Inside the metal skin 42 is arranged a structure comprising a thick perforated metal sheet 44, which is another component of the deformable internal structure 38. The plurality of thick perforated metal sheets 44 are welded to each other and to the metal skin 42. The plurality of thick holed metal sheets 44 are arranged at predetermined regular intervals, and are arranged, for example, in a horizontal plane and a vertical plane in an orthogonal coordinate system. Thereby, a plurality of thick holed metal sheets 4
4 forms a plurality of compartments 46 having a cubic shape, for example, between the sheets.

As shown in FIG. 1, a compartment 46 closest to the metal skin 42 and closest to the lattice structure of cross bars 40 contains a plurality of metal containers 48, preferably in the form of spheres. ing. These metal containers 48
Contains a material that is a chemical mixed material. Such materials can reduce the temperature of the corium when the container casing is broken and the material contacts the corium. This material is preferably a silica-based material, for example silicon dioxide.

In the embodiment of FIG. 1, a perforated dispersion plate 50 is provided on the receptacle 20,
It is supported by the flange 30. This plate 5
Numeral 0 is made of metal and arranged horizontally.

In the event of a serious accident that results in at least partial melting of the reactor core 12, the formed corium C (FIG. 1) descends toward the receptacle 20 while breaking up into small particles. . Corium penetrates through the plate 50 and into the receptacle. When moving down inside the structure made up of the perforated metal sheet 44, the small particles made of corium evaporate the water in contact. Thereby, a vapor film is formed around each particle. Therefore, a situation may occur in which a steam explosion may occur in the central portion of the receptacle 20. Under this circumstance, the deformable internal structure 38 arranged in the receptacle, in particular a side compartment 46 filled with a spherical container, and a lattice structure consisting of cross bars 40 are formed by the explosion. Constitute a protective mattress that will absorb shock waves. Therefore, the integrity of the receptacle 20 is maintained.

In the event of a steam explosion, the plurality of metal sheets forming the compartment 46 are deformed, and the destroyed container is entirely made of silica-based material contained therein. Release released material. Associated with the molten metal internal structure and with the water retained in the vessel, the mixing of this material is at a temperature substantially below the melting point of the refractory material forming the brick 24. To contribute to lowering the corium temperature. To illustrate, by mixing 14% by weight of silica, the corium temperature can be reduced by about 400 ° C. Corium temperature is approximately 2600 ° C to 280 ° C.
Given that it is 0 ° C., and that this temperature is generally very close to the temperature that the refractory brick 24 can withstand, the temperature drop due to the material is a factor in maintaining the integrity of the refractory brick 24 Thus, it greatly contributes to maintaining the integrity of the receptacle 20.

FIG. 2 shows a modification of the first embodiment of the present invention just described with reference to FIG. The main difference between this modification and the first embodiment is that
It is a deformable internal structure 38. In this modification, a grid structure composed of a plurality of cross bars 40 is actually filled over the entire receptacle 20. For this reason, the structure including the thick perforated metal sheet 44 in FIG. 1 is omitted.

As described above, a plurality of metal cross bars 40 are provided.
Are welded together and to the inner skin 26. In this configuration, a passage is formed between the bars to allow water to circulate.

This modification is different from the first embodiment shown in FIG. 1 in that a container containing a material capable of lowering the corium temperature is not provided. In this case, the reduction of the corium temperature
Due to the melting of the lattice structure consisting of the cross bars 40,
It is ensured by mixing the lattice structure with corium. Also, the lattice structure functions to promote the splitting of the corium mass to promote cooling of the corium, and that the lattice structure provides sufficient space to receive the entire amount of corium in the receptacle 20. Please be careful.

In the modification shown in FIG. 2, FIG.
Is omitted, and the upper surface of the deformable internal structure 38 accommodated in the receptacle 20 is formed in a conical shape with its apex facing downward. Thus, this upper surface functions as a permeable hopper that has a tendency to transport most of the corium C toward the central internal structure region centered on the center of the receptacle 20. In this configuration, a steam explosion is more likely to occur in a location near the central area than in other locations. Therefore, most of the thickness of the lattice structure composed of the plurality of cross bars 40 contributes to absorbing the shock wave generated by the steam explosion.

FIG. 3 shows a second modification of the first embodiment of the present invention.

As in the first modification, the deformable internal structure 38
A grid structure consisting of a plurality of cross bars 40 is filled over most of the receptacle 20. However, the spacing between the bars 40 is relatively large. For this reason, a container 48 similar to the container described with reference to FIG. 1 is inserted between the cross bars 40 inside the lattice structure. These containers 48 are preferably in the form of spheres, and contain a material capable of lowering the corium temperature, such as a silica-based material, as described above.

The shape of the upper surface of the deformable internal structure 38 is shown in FIG.
This is the same as that of the first modification described with reference to FIG.

FIG. 4 shows a second embodiment of the present invention.
This will be described with reference to FIG.

In this second embodiment of the present invention, the deformable internal structure 38 includes a plurality of metal sheets 52. The metal sheets 52 are oriented parallel to the inner surface of the receptacle 20 (specifically, the inner surface of the inner skin 26), and are arranged at regular intervals. Metal sheet 52 in the form of a spherical cap
Are connected to each other by a counter brace 54 arranged in a vertical plane passing through the axis of the vessel 10 (vertical axis). The metal sheet 52 and the counter brace 54 are welded metal members, and are arranged so that water circulation between the metal sheets is possible. For the purpose of such water circulation, a hole 56 is formed in the counter brace 54 as shown in FIG.

In the second embodiment of the present invention, a perforated dispersion plate 50 is provided on the receptacle 20, as in the embodiment of FIG. However, instead of a flat and horizontal arrangement, the perforated plate 5
0 is a conical shape with the vertex facing downward. As shown in FIG. 4, the central portion of the perforated distribution plate 50 can have a relatively large size central opening. In this case, the portion forming the periphery of the central opening is the receptacle 2
On the metal sheet 52, which is the position closest to the center of 0,
Are located.

In the second embodiment of the present invention, the deformable internal structure formed by the metal sheet 52 and the counter brace 54 absorbs a shock wave formed by a steam explosion inside the receptacle 20. Thus, the integrity of the receptacle is maintained.

Although no special material capable of reducing the temperature of the corium is used, the effect of reducing the corium temperature is ensured by the iron contained in the metal sheet 52 and the counter brace 54. By lowering the temperature of the corium to a temperature below that which the refractory brick 24 can withstand, this secondary effect of the internal structure 38 also contributes to maintaining the integrity of the receptacle 20.

FIG. 5 shows a modification of the second embodiment of the present invention.

This modification is essentially different from the second embodiment in that only a limited number (for example, two) of metal sheets 52 are provided. In this case, a limited number of metal sheets 52 are arranged near the inner surface of the receptacle 20. Further, the space formed between the metal sheets 52 is firstly provided with a counter brace 54 disposed in a vertical plane passing through the axis of the vessel, and secondly, in a plane perpendicular to these vertical planes. The module is divided into modules 58 by the provided counter brace 54 and the metal sheet 52. With the exception of module 58 located at the bottom of the receptacle, which is substantially cylindrical, other modules 5
Reference numeral 8 denotes a shape that forms a part of a sphere.

Each module 5 partitioned in this way by the metal sheet 52 and the counter brace 54
8 contains at least two layers of curved tubes arranged substantially parallel to the inner surface of the receptacle. The curved tube 60 can in particular be arranged in a zigzag layer.

The deformable internal structure thus formed has a hollow central portion of the receptacle 20 as shown in FIG.
Is denser than the embodiment. The shock wave absorbing effect and the corium temperature reducing effect at the time of steam explosion are the same as those in the second embodiment.

Metal sheet 52, counter brace 5
4, and that all metal parts formed by the tube 60 are welded together, and
Note that the modules 58 formed by these members are welded together.

In the configuration described with reference to FIG.
The tube 60 of each module 58 can form a container in which at least a portion of a material, such as a silica-based material, that can lower the corium temperature when in contact with the corium, is provided. Can be filled.

Hereinafter, a third embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 6, in this embodiment, the deformable internal structure 3 accommodated in the receptacle 20
8 has a honeycomb structure 61. The honeycomb structure 61 extends over a predetermined thickness, and covers the inner surface of the receptacle 20. The partition wall of the honeycomb structure 61 is oriented substantially radially with respect to the center of the receptacle. In other words, it is radial and substantially perpendicular to the inner surface of the receptacle.
These partitions form a plurality of vesicles, and the cross-sectional shape of these vesicles can be any shape, particularly a hexagon or a circle.

The honeycomb structure 61 is made of metal, and the inner surface is lined with a metal skin 62.

The effect of the honeycomb structure 61 is the same as that described above with reference to FIGS.

By filling, at least in part, a suitable material, for example a silica-based material, into a container formed by the cells forming the honeycomb structure 61,
Note that a rapid cooling effect of the corium received in the receptacle 20 can be obtained.

Finally, a fourth embodiment of the present invention will be described with reference to FIG.

In this embodiment, the receptacle 2
The deformable internal structure 38 housed in the housing 0 comprises a metal tube 64. The metal tubes 64 are welded together and arranged in a continuous layer substantially parallel to the inner surface of the receptacle 20. The tube 64 is arranged in a zigzag layer. The upper end of the tube is welded to the perforated distribution plate 50 with the upper end communicating with the space above the plate via an opening in the plate.
The lower end of each tube 64 is welded to a cylindrical perforated collar 66 about the vertical axis of the reactor vessel 10. This communicates the lower end of the tube through the opening in the collar 66 into the central collector 68. Everything at the lower end of the tube connected to the collar 66 abuts against each other. However, the tubes gradually diverge from each other as they rise toward perforated distribution plate 50. Collector 6
The upper end of 8 is closed by a perforated plate 70.

In this configuration, the water circulation is directed inside the tube 64 toward the collector 68 and further upward through the perforated plate 70, and so forth.
Consists of natural convection.

In the event of a steam explosion, the tubes 64, collar 66, and perforated plate 70 function similarly to those specifically described above with reference to FIGS.

It is clear that the various embodiments and modifications described above are merely examples of the deformable internal structure 38 disposed inside the receptacle 20. More generally, the present invention can be applied to any type of water-based reactor, regardless of the configuration of the core and associated internal equipment. Also, the shape and structure of the receptacle
Other than those exemplified above can be used. further,
Although it is preferable to provide the space 22 and the ring collector 34, they may be omitted in some cases.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing a lower part of a water utilization type nuclear reactor, and a vessel of the nuclear reactor includes a receptacle according to a first embodiment of the present invention.

FIG. 2 is a sectional view similar to FIG. 1, showing a first embodiment of the present invention;
A modification of the embodiment is shown.

FIG. 3 is a sectional view similar to FIGS. 1 and 2, showing a second modified example of the first embodiment of the present invention.

FIG. 4 is a sectional view similar to FIGS. 1 to 3, showing a second embodiment of the present invention.

FIG. 5 is a sectional view similar to FIGS. 1 to 4, showing a modification of the second embodiment of the present invention.

FIG. 6 is a cross-sectional view similar to FIGS. 1 to 5, showing a third embodiment of the present invention.

FIG. 7 is a sectional view similar to FIGS. 1 to 6, showing a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vessel 12 Reactor core 20 Receptacle 22 Space 38 Deformable internal structure 40 Intersecting bar 44 Perforated metal sheet 46 Separator 48 Container 50 Perforated dispersion plate 52 Metal sheet 54 Counter brace 58 Module 60 Tube 61 Honeycomb structure 64 Tube 68 Center Collector C Corium

Claims (18)

[Claims] 1. A water-based reactor comprising a vessel and a reactor core housed in the vessel, wherein the reactor is housed below the core in the vessel and at least partially. Comprises a basin-shaped receptacle formed from a refractory material, the receptacle being capable of receiving corium formed upon accidental melting of the core, wherein the receptacle is at least near an inner surface of the receptacle. A nuclear reactor having a deformable internal structure. 2. The nuclear reactor according to claim 1, wherein the deformable internal structure is a metal structure configured to enable circulation of water in the structure. Reactor. 3. The nuclear reactor according to claim 1, wherein said receptacle further comprises a container, and said container contains a material capable of lowering the temperature of said corium when coming into contact with said corium. A nuclear reactor. 4. A nuclear reactor according to claim 3, wherein said material capable of lowering the corium temperature contains silica. 5. The nuclear reactor according to claim 3, wherein said container is spherical. 6. The nuclear reactor according to claim 3, wherein the deformable internal structure has a lattice structure including a plurality of cross bars disposed on the inner surface of the receptacle. Furnace. 7. A nuclear reactor according to claim 6, wherein said lattice structure comprising said plurality of cross bars is filled over a majority of said receptacle. 8. The nuclear reactor according to claim 7, wherein said container is accommodated between said plurality of cross bars. 9. The reactor according to claim 6, wherein the deformable internal structure further includes a structure formed of a perforated metal sheet inside the lattice structure including the plurality of cross bars. The metal sheet forms a plurality of compartments, and the container is housed in at least one of the plurality of compartments that is located closest to the grid structure including the plurality of cross bars. A nuclear reactor characterized by being made. 10. The nuclear reactor of claim 3, wherein said deformable internal structure is spaced apart from each other substantially parallel to said inner surface of said receptacle; A nuclear reactor, comprising: a counter brace for connecting these metal sheets. 11. The nuclear reactor according to claim 10, wherein said metal sheet and said counter brace form a plurality of modules, said modules being oriented substantially parallel to said inner surface of said receptacle. A nuclear reactor comprising a plurality of tubes. 12. The nuclear reactor according to claim 11, wherein said tube forms said container. 13. The nuclear reactor according to claim 3, wherein the deformable internal structure has a honeycomb structure, and a partition wall of the honeycomb structure is substantially perpendicular to the inner surface of the receptacle. A nuclear reactor. 14. The nuclear reactor according to claim 13, wherein the cells partitioned by the honeycomb structure constitute the container. 15. The nuclear reactor of claim 1, wherein said deformable internal structure comprises a plurality of tubes, said tubes being in a plurality of continuous layers substantially parallel to said inner surface of said receptacle. A nuclear reactor which is arranged and communicates with a central collector installed at the bottom of said receptacle. 16. The nuclear reactor according to claim 1, wherein a perforated distribution plate is provided on the receptacle. 17. The nuclear reactor according to claim 16, wherein the perforated distribution plate has a conical shape with a vertex facing downward. 18. The reactor according to claim 1, wherein the receptacle is isolated from a bottom of the vessel by a space opened on an upper side.