Concrete structure and reactor containment vessel

Abstract

To provide a concrete structure capable of preventing foreign matter from entering a steam exhaust pipe during concrete placing as well as after completion, and reactor containment vessel using the concrete structure.SOLUTION: A concrete structure comprises a concrete skeleton 2, a steel plate (an inner steel plate) 3 stretched on a surface of the concrete skeleton 2 via studs 8, and a steam exhaust pipe 10 buried inside the concrete skeleton 2 for exhausting steam generated from the concrete skeleton 2 when the concrete skeleton 2 is exposed to high temperatures. The steam exhaust pipe 10 includes one end disposed at a boundary part between the concrete skeleton 2 and the steel plate 3, and the other end disposed outside the concrete skeleton 2, and the steam exhaust pipe 10 includes a steam introduction mechanism 11 at least at one end for introducing steam into the steam exhaust pipe 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a concrete structure and a nuclear reactor containment vessel. [Background technology]

[0002] In steel plate concrete structures or reinforced concrete structures used in reactor containment vessels, etc., when the concrete structure becomes hot, the water contained inside the concrete evaporates, creating back pressure at the interface between the steel plate and the concrete structure, which can lead to stud pull-out and out-of-plane deformation of the inner steel plate.

[0003] Therefore, in order to suppress the back pressure that causes the steel plates to deform out of plane, a concrete structure has been proposed in which a steam exhaust pipe is installed in contact with the back surface of the inner steel plate of the reactor containment vessel and that leads steam to the outside of the concrete structure through a pipe opening provided in the outer steel plate (see, for example, Patent Document 1). In the concrete structure of Patent Document 1, one end of the steam exhaust pipe, which has a small opening formed therein, is embedded in the concrete, and the steam generated from the concrete is led from the small opening through the inside of the steam exhaust pipe to the outside of the containment vessel. When pouring the concrete, a small opening closing jig made of a small diameter pipe or the like is inserted into the steam exhaust pipe to prevent foreign matter such as concrete from flowing into the pipe through the small opening. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-163799 Summary of the Invention [Problem to be solved by the invention]

[0005] The small opening closing jig in Patent Document 1 is intended to prevent foreign matter from entering the steam exhaust pipe during concrete pouring, and is removed after construction. As a result, it is unable to prevent foreign matter from entering the steam exhaust pipe during operation, which reduces the steam exhaust effect.

[0006] An object of the present invention is to solve the above-mentioned problems and to provide a concrete structure that can prevent foreign matter from entering the steam exhaust pipe not only during concrete pouring but also after completion, and a reactor containment vessel using the same. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention provides a concrete structure comprising: a concrete body; a steel plate stretched over the surface of the concrete body via studs; and a steam exhaust pipe buried inside the concrete body for exhausting steam generated from the concrete body when the concrete body is exposed to high temperatures, wherein one end of the steam exhaust pipe is located at the boundary between the concrete body and the steel plate and the other end is located outside the concrete body, and the steam exhaust pipe is equipped at at least one end with a steam introduction mechanism for introducing the steam into the steam exhaust pipe. [Effects of the Invention]

[0008] According to the concrete structure and reactor containment vessel of the present invention, it is possible to prevent foreign matter from entering the steam exhaust pipe not only during concrete pouring but also after completion. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a concrete structure according to a first embodiment of the present invention. [Figure 2] 1 is a partially cutaway perspective view showing a concrete structure according to a first embodiment of the present invention. [Figure 3] FIG. 2 is a cross-sectional view showing a concrete structure according to a modified example of the first embodiment of the present invention. [Figure 4A]FIG. 4 is a cross-sectional view showing a concrete structure according to a second embodiment of the present invention. [Figure 4B] FIG. 10 is an enlarged cross-sectional view of a main part showing a state of steam being discharged from a concrete structure according to a second embodiment of the present invention. [Figure 5] FIG. 10 is a cross-sectional view showing a concrete structure according to a third embodiment of the present invention. [Figure 6A] FIG. 10 is a cross-sectional view showing a concrete structure according to a fourth embodiment of the present invention. [Figure 6B] FIG. 10 is an enlarged cross-sectional view of a main part showing a state of a concrete structure according to a fourth embodiment of the present invention when steam is being discharged. DETAILED DESCRIPTION OF THE INVENTION

[0010] (First embodiment) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Fig. 1 is a cross-sectional view showing a concrete structure according to a first embodiment, and Fig. 2 is a partially cutaway perspective view showing the concrete structure according to the first embodiment. The concrete structure of the present invention can be used in the wall of a nuclear reactor containment vessel.

[0011] Advanced boiling water reactors (ABWRs) use reinforced concrete containment vessels (RCCVs). RCCVs maintain airtightness by lining the inside of the concrete frame with a steel liner, preventing radioactive materials from leaking to the outside in the event of an accident, and the reinforced concrete is designed to withstand earthquakes, pressure, and other loads. In recent years, the use of steel-plated concrete structures with the same strength and leak resistance as RCCVs for reactor containment vessels has been considered. The concrete structure of the present invention can be applied to both a structure in which the inner surface of a concrete body is lined with a steel liner and a steel plate concrete structure. In this embodiment, the concrete structure of the present invention will be described as being used in a nuclear reactor containment vessel having a steel plate concrete structure.

[0012] As shown in Figures 1 and 2, the concrete structure 1 of this embodiment comprises a concrete body 2, steel plates 3 and 4 stretched on the surface of the concrete body 2 via studs 8, and a steam exhaust pipe 10.

[0013] The concrete skeleton 2 is constructed by pouring concrete between a pair of steel plates 3, 4, and has a predetermined thickness. High-fluidity concrete is used for the concrete skeleton 2.

[0014] The steel plates 3, 4 include an inner steel plate 3 arranged on the inner surface of the containment vessel and an outer steel plate 4 arranged on the outer surface. Studs 8 are installed on the opposing surfaces of the inner steel plate 3 and the outer steel plate 4 (the surfaces facing the concrete body 2) to anchor the inner steel plate 3 and the outer steel plate 4 to the concrete body 2. Each stud 8 has an anchoring plate at its tip, and multiple studs 8 are installed at predetermined intervals in the vertical and horizontal directions. The inner steel plate 3 is the steel plate that forms the inside of the wall of the reactor containment vessel and is exposed to high temperatures in the event of an accident. The inner steel plate 3 and the outer steel plate 4 are arranged facing each other with a gap equal to the thickness of the concrete body 2. The inner steel plate 3 and the outer steel plate 4 also serve as formwork when pouring the concrete for the concrete body 2. An opening 7 is formed in the outer steel plate 4 for passing the steam exhaust pipe 10 through. The opening 7 is, for example, circular and has an inner diameter that is larger than the outer diameter of the steam exhaust pipe 10 by a predetermined length.

[0015] The steam exhaust pipe 10 is used to exhaust steam generated when the concrete body 2 is exposed to high temperatures to the outside. The steam exhaust pipe 10 is made of, for example, a steel pipe. One end of the steam exhaust pipe 10 is located inside the concrete body 2, at the boundary between the concrete body 2 and the inner steel plate 3. The other end of the steam exhaust pipe 10 has small openings 12. The small openings 12 are holes that allow steam generated outside the steam exhaust pipe 10 to flow into the steam exhaust pipe 10 and be discharged, and are formed by penetrating the pipe body in the thickness direction. A plurality of small openings 12 are formed around the entire circumference of the pipe body. One end of the steam exhaust pipe 10 is fixed to the inner steel plate 3 via a support leg 13. The support leg 13 is made of a metal rod-shaped member that is bent midway and V-shaped in side view. One end is welded to the surface of the inner steel plate 3 facing the concrete body 2, and the other end is welded to the surface of the steam exhaust pipe 10. The other end of the support leg 13 is welded to a position that does not interfere with the small opening 12. The support legs 13 are installed, for example, at four locations on the outer circumferential surface of the steam exhaust pipe 10, each at the top, bottom, left, and right (see FIG. 2).

[0016] The other end of steam exhaust pipe 10 is located on the outer steel plate 4 side and is disposed outside, protruding from the surface of concrete body 2. The protruding portion of the other end of steam exhaust pipe 10 from concrete body 2 passes through opening 7 of outer steel plate 4 and protrudes outward, exposing the inside of steam exhaust pipe 10 to the outside.

[0017] The steam exhaust pipe 10 is equipped with a steam introduction mechanism 11 at at least one end. The steam introduction mechanism 11 introduces steam into the steam exhaust pipe 10 when steam is generated inside the concrete body 2, while normally preventing concrete debris and the like from entering the interior of the steam exhaust pipe 10. The steam introduction mechanism 11 is composed of a waterproof, moisture-permeable material 14. The waterproof, moisture-permeable material 14 is a sheet-like member that is wrapped around one end of the steam exhaust pipe 10 to cover the area where the small opening 12 is formed. The waterproof, moisture-permeable material 14 is equipped with an air vent (not shown) that allows only steam to pass through. The air vent does not allow solids such as concrete debris to pass through.

[0018] To install the concrete structure 1 having the above configuration, first, the steam exhaust pipe 10 is fixed to the inner steel plate 3, to which the studs 8 are attached, via the support legs 13. A waterproof and breathable material 14 is wrapped around one end of the steam exhaust pipe 10 to cover the small opening 12. A small opening closure member 15 is inserted into the steam exhaust pipe 10 to prevent foreign matter from entering the small opening 12 during concrete pouring. The small opening closure member 15 is composed of a balloon-shaped elastic member and is inserted from the other end of the steam exhaust pipe 10 to one end and then inflated. Note that, when the steam exhaust pipe 10 is linear, as in this embodiment, the small opening closure member 15 may be a linear rod-shaped member. Then, the outer steel plate 4, to which the studs 8 are attached, is placed opposite the inner steel plate 3, and concrete is poured. At this time, the small opening closure member 15 inserted into the steam exhaust pipe 10 prevents foreign matter from entering the small opening 12. In this embodiment, the area where the small opening 12 is formed is covered with the waterproof and moisture-permeable material 14, which further increases the effect of preventing foreign matter from getting mixed in. After the concrete has cured, the small opening closing member 15 is pulled out of the steam exhaust pipe 10, and the concrete structure 1 is completed.

[0019] According to the concrete structure 1 of this embodiment, after the small opening closing member 15 is pulled out, the small opening 12 is covered with the waterproof and moisture-permeable material 14. Therefore, even if fragments of the concrete body 2 are generated during operation of the reactor, the waterproof and moisture-permeable material 14 can prevent the fragments from entering the small opening 12. In other words, it is possible to prevent foreign matter from entering the steam exhaust pipe 10 not only during concrete pouring but also after the concrete structure 1 is completed.

[0020] Furthermore, since the waterproof and breathable material 14 allows steam to pass through, even if the temperature on the inner steel plate 3 side becomes high and steam is generated from the concrete structure 2, the steam can be introduced into the steam exhaust pipe 10 through the waterproof and breathable material 14 and the small opening 12 and then discharged to the outside of the concrete structure 2.

[0021] By constructing a reactor containment vessel using the concrete structure 1, even if the reactor temperature rises, steam generated in the concrete skeleton 2 can be discharged to the outside, preventing deformation of the inner steel plate 3. Therefore, a reactor containment vessel with high airtightness can be provided.

[0022] (Modification of the first embodiment) Fig. 3 is a cross-sectional view showing a concrete structure according to a modified example of the first embodiment. A concrete structure 1a according to the modified example will be described with reference to Fig. 3. As shown in Fig. 3, this concrete structure 1a differs from the above embodiment in that the steam exhaust pipe 10a is not straight but is bent in a crank shape. Note that other configurations are similar to those of the first embodiment, so the same reference numerals are used and description thereof will be omitted.

[0023] When pouring concrete, a small opening closing member 15 made of a balloon-shaped elastic material is inserted into the bent steam exhaust pipe 10a. The small opening closing member 15 is preferably inserted into the steam exhaust pipe 10a before the steam exhaust pipe 10a is fixed to the inner steel plate 3, and then inflated before pouring the concrete. This makes it easier to insert the small opening closing member 15 into the steam exhaust pipe 10a. After the concrete has cured, the small opening closing member 15 can be easily removed from the steam exhaust pipe 10a by releasing the air from the small opening closing member 15 to make it deflated. The concrete structure 1a according to the modified example can also achieve the same effects as the concrete structure 1 of the first embodiment.

[0024] Second Embodiment Next, a concrete structure 1b according to a second embodiment will be described. Fig. 4A is a cross-sectional view showing the concrete structure according to the second embodiment, and Fig. 4B is an enlarged cross-sectional view of a main part showing the state of the concrete structure when steam is being discharged. The concrete structure 1b according to the second embodiment differs from the first embodiment described above in the shape of the steam discharge pipe 10b and the structure for fixing it to the inner steel plate 3. Note that the other components are the same as those in the first embodiment, so the same reference numerals are used and their description will be omitted.

[0025] As shown in Fig. 4A, the steam exhaust pipe 10b of this embodiment is a steel pipe that does not have a small opening and is open on both sides. One end of the steam exhaust pipe 10b is arranged with a gap between it and the inner steel plate 3. Steam generated in the concrete structure 2 passes through the gap between the steam exhaust pipe 10b and the inner steel plate 3.

[0026] One end of the steam exhaust pipe 10b is fixed to the inner steel plate 3 by a low-melting-point material 16. The low-melting-point material 16 is made of a material, such as solder, that has a lower melting point than the inner steel plate 3 and the steam exhaust pipe 10b (made of steel pipe), and melts when the temperature exceeds a predetermined value. The predetermined value for the melting temperature of the low-melting-point material 16 is higher than the temperature of the hydration reaction when concrete solidifies (approximately 90°C to 110°C) and lower than the temperature at which steam is generated in the concrete skeleton 2. The low-melting-point material 16 is applied so as to cover the gap. The low-melting-point material 16 has a truncated cone shape whose diameter decreases with increasing distance from the inner steel plate 3, and the small-diameter portion at the tip covers the outer surface of the steam exhaust pipe 10b.

[0027] With the steam exhaust pipe 10b configured as described above, the low-melting-point material 16 does not melt during concrete pouring and curing, thereby ensuring reliable fixation of the steam exhaust pipe 10b. Furthermore, the low-melting-point material 16 covers the gap between the steam exhaust pipe 10b and the inner steel plate 3, preventing concrete from flowing into the gap and preventing the intrusion of foreign matter into the steam exhaust pipe 10b. When steam is generated in the concrete structure 2, as shown in FIG. 4B , the low-melting-point material 16 melts, forming a space S1 between the inner steel plate 3, one end of the steam exhaust pipe 10b, and the concrete structure 2. This space S1, together with the gap, serves as a space through which steam generated in the concrete structure 2 passes. Therefore, steam generated in the concrete structure 2 passes through the space S1 and the gap, is introduced into the steam exhaust pipe 10b (see the arrow in FIG. 4B ), and is then discharged to the outside. In other words, in this embodiment, the low-melting-point material 16 constitutes the steam introduction mechanism 11. As described above, the concrete structure 1b of this embodiment can achieve the same effects as the first embodiment, and can prevent foreign matter from entering the steam exhaust pipe 10 not only during concrete pouring but also after the concrete structure 1b is completed.

[0028] (Third embodiment) Next, a concrete structure 1c according to a third embodiment will be described. Fig. 5 is a cross-sectional view showing a concrete structure according to the third embodiment. The concrete structure 1c according to the third embodiment differs from the first embodiment in the shape of the steam exhaust pipe 10c. Note that other configurations are the same as those of the first embodiment, so the same reference numerals are used and descriptions thereof will be omitted.

[0029] As shown in FIG. 5 , the steam exhaust pipe 10c of this embodiment is a steel pipe with no small openings and open on both sides. One end of the steam exhaust pipe 10c is positioned with a gap between it and the inner steel plate 3. Steam generated in the concrete structure 2 passes through the gap between the steam exhaust pipe 10c and the inner steel plate 3. One end of the steam exhaust pipe 10c is fixed to the inner steel plate 3 via a support leg 13 similar to that of the first embodiment. A pressure relief valve 17 is attached to the inside of one end of the steam exhaust pipe 10c. The pressure relief valve 17 may be, for example, a rupture disk. When steam is generated in the concrete structure 2, the pressure outside the one end of the steam exhaust pipe 10c increases. This pressure increase causes a disk made of, for example, a fluororesin of the rupture disk to rupture, opening the pressure relief valve 17. The pressure at which the disk ruptures is set lower than the pressure at which steam is generated in the concrete structure 2 and the inner steel plate 3 deforms. When the pressure release valve 17 is opened, the steam outside one end of the steam exhaust pipe 10c is introduced into the steam exhaust pipe 10c and is exhausted to the outside from the other end of the steam exhaust pipe 10c. That is, in this embodiment, the pressure release valve 17 constitutes the steam introduction mechanism 11.

[0030] With the steam exhaust pipe 10c configured as described above, the pressure relief valve 17 is closed during concrete pouring and curing, preventing concrete from flowing into the steam exhaust pipe 10c and preventing the intrusion of foreign matter into the steam exhaust pipe 10c. When steam is generated in the concrete structure 2, the disk of the rupture disk ruptures, opening the pressure relief valve 17. This connects the outside (concrete structure 2 side) of the steam exhaust pipe 10c to the inside, allowing the steam to be introduced into the steam exhaust pipe 10c and then discharged to the outside from the other end. As described above, the concrete structure 1b of this embodiment can achieve the same effects as the first embodiment, preventing the intrusion of foreign matter into the steam exhaust pipe 10b not only during concrete pouring but also after the concrete structure 1b is completed.

[0031] (Fourth embodiment) Next, a concrete structure 1d according to a fourth embodiment will be described. Fig. 6A is a cross-sectional view showing a concrete structure according to the fourth embodiment, and Fig. 6B is an enlarged cross-sectional view of a main part showing the state of the concrete structure when steam is being discharged. The concrete structure 1d according to the fourth embodiment differs from the first embodiment in the shape of the steam discharge pipe 10d. Note that the other components are the same as those of the first embodiment, so the same reference numerals are used and the description will be omitted.

[0032] As shown in FIG. 6A, the steam exhaust pipe 10d of this embodiment has a small opening 18 for steam exhaust. However, the small opening 18 has a larger diameter than the small opening 12 of the first embodiment, and a female thread is formed on the inner circumferential surface. The steam introduction mechanism 11 of this embodiment is composed of a blocking member 19 that blocks the small opening 18. The blocking member 19 is, for example, a bolt attached to the small opening 18. A shaft 19b of the bolt is threaded into the small opening 18, and a head 19a protrudes outside the steam exhaust pipe 10d. The bolt is made of a low-melting-point material that melts when the temperature exceeds a predetermined value. The low-melting-point material is, for example, made of resin. The melting temperature of resin is higher than the temperature of the hydration reaction when concrete solidifies (approximately 90°C to 110°C) and lower than the temperature at which steam is generated in the concrete skeleton 2.

[0033] With the steam exhaust pipe 10d configured as described above, the blocking member 19 does not melt and blocks the small opening 18 during concrete pouring and curing, preventing the intrusion of foreign matter into the steam exhaust pipe 10d. When steam is generated in the concrete structure 2, as shown in FIG. 6B, the blocking member 19 melts, forming a space S2 where the portion where the bolt head 19a was located and the small opening 18 where the shank 19b was threadedly engaged join together. This space S2 connects the outside (concrete structure 2 side) and inside of the steam exhaust pipe 10c. In other words, space S2 is a space through which steam generated in the concrete structure 2 passes, and the steam is introduced into the inside of the steam exhaust pipe 10d (see the arrow in FIG. 6B) and discharged to the outside from the other end of the steam exhaust pipe 10d. As described above, the concrete structure 1d of this embodiment can achieve the same effects as the first embodiment, and can prevent foreign matter from entering the steam exhaust pipe 10d not only during concrete pouring but also after the concrete structure 1d is completed.

[0034] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and each component can be modified as appropriate without departing from the spirit of the present invention. For example, in the second embodiment, a gap is provided between the inner steel plate 3 and one end of the steam exhaust pipe 10b around the entire circumference, but the present invention is not limited to this. A notch extending in the axial direction may be formed at one end of the steam exhaust pipe 10b, and the portion where the notch is not formed may be configured to abut against the inner steel plate 3. In this case, a gap is formed between the inner steel plate 3 and the notch portion, and the notch portion serves as a space through which steam passes.

[0035] Furthermore, although the set value of the melting temperature of the low-melting point material 16 in the second embodiment is lower than the temperature at which steam is generated in the concrete skeleton 2, it is not limited to this. The set value may be higher than the temperature at which steam is generated from the concrete skeleton 2, as long as it is lower than the temperature at which the inner steel plate 3 is deformed. Even at such a set value, the inner steel plate 3 does not deform, so the airtightness of the containment vessel can be maintained.

[0036] Furthermore, in the fourth embodiment, the closing member 19 is a resin bolt, but this is not limited to this. For example, it may be a pin-shaped resin member that is press-fitted into the small opening. In this case, it is not necessary to provide a female thread on the small opening and a male thread on the closing member.

[0037] In the above embodiments, the concrete structure 1 of each embodiment is applied to a steel plate concrete structure, but is not limited to this. For example, it may be applied to a half steel plate concrete structure in which steel plates are provided only on the inside of the concrete skeleton 2. Furthermore, the concrete structure 1 can also be applied to structures other than nuclear reactor containment vessels that require airtightness. [Explanation of symbols]

[0038] 1,1a Concrete structure 2. Concrete structure 3 Inner steel plate (steel plate) 8 studs 10 Steam exhaust pipe 11 Steam introduction mechanism 12 Small opening 14 Waterproof and breathable material 1b Concrete structure 10b Steam exhaust pipe 16 Low melting point materials 1c Concrete structure 10c Steam exhaust pipe 17 Pressure relief valve 1d concrete structure 10d Steam exhaust pipe 18 Small Openings 19 Closure element

Claims

1. The concrete structure and a steel plate stretched on the surface of the concrete frame via studs; a steam exhaust pipe that is embedded inside the concrete skeleton and that exhausts steam generated from the concrete skeleton when the concrete skeleton is exposed to high temperatures; one end of the steam exhaust pipe is disposed at a boundary between the concrete skeleton and the steel plate, and the other end is disposed outside the concrete skeleton; The steam exhaust pipe has a steam introduction mechanism at at least one end thereof for introducing the steam into the steam exhaust pipe. A concrete structure characterized by:

2. A small opening for discharging steam is formed at one end of the steam discharge pipe, The vapor introduction mechanism includes a waterproof and breathable material covering an area where the small opening is formed, The waterproof and breathable material has ventilation holes that allow only vapor to pass through.

2. The concrete structure according to claim 1.

3. One end of the steam exhaust pipe is arranged with a gap between it and the steel plate, the steam introduction mechanism is made of a low-melting-point material that fixes the steam exhaust pipe and the steel plate, The low-melting-point material is applied to cover the gap and melts when the temperature exceeds a predetermined value.

2. The concrete structure according to claim 1.

4. One end of the steam exhaust pipe is arranged with a gap between it and the steel plate, the steam introduction mechanism is configured with a pressure release valve provided at one end of the steam exhaust pipe, The pressure relief valve is opened when the steam is generated and the pressure on the concrete body side exceeds a set value, and the steam is released into the steam exhaust pipe.

2. The concrete structure according to claim 1.

5. A small opening for discharging steam is formed at one end of the steam discharge pipe, the vapor introduction mechanism is configured with a blocking member that blocks the small opening, The blocking member is made of a low-melting-point material that melts when the temperature exceeds a predetermined value.

2. The concrete structure according to claim 1.

6. A concrete structure according to any one of claims 1 to 5 is provided. A nuclear reactor containment vessel characterized by:

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