KR100743405B1 - Fiber-reinforced concrete cask, supporting frame for molding thereof and process for producing the concrete cask - Google Patents

Abstract

Fiber-reinforced concrete cask and its manufacturing method which can be easily installed, can reduce construction cost, have excellent strength, durability and heat resistance, and can minimize the occurrence of cracks, and support frame for forming the concrete cask This is provided. In particular, at least the outer circumferential surface of the concrete cask 10 formed by injecting and solidifying the concrete 11 is provided with a reinforcing fiber sheet having a coefficient of thermal expansion equal to or less than that of the concrete 11. The sheet is provided on at least one of the outer circumferential surface and the inner circumferential surface of the concrete cask 10, and the inner circumferential surface of the outer sheet 21 and the outer circumferential surface of the inner sheet 22 are connected to each other by a reinforcing fiber string 23. Preferably, carbon fibers are used as reinforcing fibers.

Description

FIBER-REINFORCED CONCRETE CASK, SUPPORTING FRAME FOR MOLDING THEREOF AND PROCESS FOR PRODUCING THE CONCRETE CASK}

The present invention relates to a fiber reinforced concrete cask used for the transport and storage of radioactive material, a support frame for forming the same, and a method for producing the concrete cask.

When transporting or storing radioactive material with high levels of radiation and high decay heat, such as spent fuel generated at a nuclear power plant, the container containing it must have sufficient radiation shielding, sealing, cooling and structural strength. In general, these containers are made of reinforced concrete or steel plate concrete, but the reality still contains a problem. One of the problems is the difference in thermal expansion coefficient between concrete and steel reinforcement.

The strength of the container is improved by reinforcing the inside or the outside of the concrete with the steel member. However, since the steel has a higher coefficient of thermal expansion as compared to the concrete, when the package is a pyrogenic material, the concrete may be cracked and damaged. In addition, since concrete has lower thermal conductivity than metal, another problem arises in that it is difficult to discharge heat generated from the inside to the outside, which further increases the occurrence of cracks caused by the difference in thermal expansion coefficient.

Therefore, JP 2000-162384A provides a concrete cask that can prevent the concrete cask body container from becoming hot.

As shown in FIG. 4, this concrete cask 51 includes a concrete 55 formed in a bottomed cylindrical shape and an inner metal cylinder 56 of the inner circumference of the body container 53. The canister 52 is inserted into the container and the upper opening is sealed with the lid 54. There is a cooling air distribution space 57 between the outer surface of the canister 52 and the main body container 53, in which a cooling air supply passage 58 and a cooling air discharge passage 59 are formed.

As described above, the structure in which heat in the main body container can be discharged to the outside by the cooling air can improve the durability and heat resistance of the container.

Moreover, in order to form the inner metal cylinder 56 as a reinforcement of the concrete cask, it is also proposed to use a metal such as stainless steel having a coefficient of thermal expansion approximately equal to that of concrete, and accordingly damage to the main body container while maintaining strength Can be minimized.

In addition, JP 2000-265435A discloses the use of a fiber sheet such as polyethylene as a support frame in a concrete structure in which construction work is simplified and construction cost is reduced as compared with the case of using steel as a reinforcing material. According to this invention, a jacket having a space portion is formed between the outer sheet and the inner sheet, and the sea is injected into the space portion of the jacket, soaked in the sea and held at the seabed, and then the concrete is stored in the space portion. Structures are prepared by solidification by filling and replacing water.

However, only by forming the cooling air circulation space as in JP 2000-162384A, when the calorific value is large, such as a high temperature heating element, the difference in thermal expansion rate cannot be absorbed and cracking cannot be avoided. In addition, in the case of using the stainless steel, there is a problem that the production of the support frame is laborious and the material cost is high.

On the other hand, although the concrete structure of the said patent publication 2000-265435 is suitable for a low temperature material, since a fiber sheet, such as polyethylene, is used as a support frame, a problem remains in strength and heat resistance.

The present invention has been developed in view of these problems of the prior art. An object of the present invention is to provide a fiber-reinforced concrete cask and a method of manufacturing the same, which can be easily constructed, can reduce construction costs, and are excellent in strength, durability, and heat resistance, and can minimize cracks. It is to provide a support frame for k-molding.

In order to solve this problem, the present invention is a fiber-reinforced concrete cask is formed by injecting and solidifying concrete, the reinforcing fiber sheet is disposed on at least the outer peripheral surface of the cask, the reinforcing fiber sheet is equal to the thermal expansion coefficient of the concrete or It has a coefficient of thermal expansion below that.

In this case, the reinforcing fiber sheet is preferably disposed on the outer circumferential surface and the inner circumferential surface of the concrete cask, and the reinforcing fiber sheets on the outer circumferential surface and the inner circumferential surface of the concrete cask are connected by a string.

Moreover, the reinforcing fibers are preferably carbon fibers.

According to the present invention described above, as in the prior art, by the heat generated in the contents of the cask, by expanding or pulling the concrete of the steel reinforcement or frame used in the cask excellent durability, heat resistance without cracking or peeling of the reinforcement material It is possible to manufacture concrete casks.

In addition, the fiber-reinforced concrete cask of the present invention is characterized in that the concrete is formed by injecting concrete into a cylindrical bag-shaped support frame formed by a reinforcing fiber sheet having a thermal expansion rate equal to or less than that of concrete. The "cylindrical bag type" refers to a bag-shaped structure having a hollow cylinder, a hollow cylinder with a bottom (cylindrical container) and a cylinder including a solid cylinder as a bottom plate.

Moreover, by using a carbon fiber having a negative thermal expansion rate as the reinforcing fiber, such carbon fiber shrinks in response to a rise in temperature due to heat generated inside the cask to exert a compressive force on concrete (weak to tensile strength and strong against compressive force). Thus, the strength of the concrete can be significantly improved.

The reinforcing fiber needs to use a fiber having high strength to withstand the injection of concrete and at the same time high heat resistance to accommodate the heating element. The string is also preferably formed of reinforcing fibers such as carbon fibers.

In addition, the present invention is characterized in that the support frame for forming a concrete cask is formed of a reinforcing fiber sheet having a coefficient of thermal expansion equal to or less than that of concrete.

In addition, the present invention, the support frame forms a double wall structure in which the outer sheet and the inner sheet is connected, the outer sheet and the inner sheet are connected by a string, and the support frame is sewn in a cylindrical bag shape, the reinforcing fiber sheet Is done.

As described above, the "cylindrical pocket" includes a bag-shaped structure having a hollow cylinder, a hollow cylinder with a bottom (cylindrical container) and a cylinder including a solid cylinder as a bottom plate.

According to this invention, it is possible to form a support frame of the concrete cask having the effect of the present invention. In addition, according to the invention it is preferable to form a concrete injection hole in the lower portion of the support frame.

According to the present invention, a preferred method of manufacturing a concrete cask is a process of forming a support frame for concrete injection into a reinforced fiber sheet having a thermal expansion rate equal to or less than that of concrete, wherein the concrete is added to the support frame. It is characterized by having a step of injecting. In the forming step of the supporting frame, it is preferable to connect the outer sheet and the inner sheet constituting the supporting frame by a string.

In this case, the pressure at the time of the concrete injection remains as a tensile force on each sheet of the support frame, but since the repulsive force from the concrete is lost after the curing of the concrete, the sheet shrinks conversely, giving compression prestress to the concrete from the outside. It is possible to produce a concrete structure that effectively utilizes the characteristics of concrete that is weak in tensile strength of concrete but strong against compression.

And a step of filling the support frame shape holding fluid into the formed support frame after the forming of the support frame, wherein the support frame shape holding fluid is prefilled by injecting concrete from the bottom of the support frame in the concrete injection process. It is more preferable to substitute with.

As the supporting frame shape holding fluid, a fluid that is easy to handle and has a specific gravity smaller than concrete, such as water or air, is preferable.

According to this invention, it is possible to stably manufacture a concrete cask having an accurate shape by filling the supporting frame shape maintaining fluid in advance and replacing it with concrete, thereby eliminating troublesome mold frames such as steel frames.

That is, according to the present invention, it is possible to manufacture a concrete cask that can be easily constructed and can reduce construction costs, and is excellent in strength, durability and heat resistance, and can minimize the occurrence of cracks.

1 is a perspective view of a fiber reinforced concrete cask according to an embodiment of the present invention.

(A) is sectional drawing along the A-A line of FIG. 1, and FIG. 2 (b) is sectional drawing along the B-B line of FIG.

3 is a schematic view showing a manufacturing process of an embodiment of a fiber reinforced concrete cask according to the present invention.

4 is an external perspective view of a concrete cask in the prior art.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In this embodiment, the dimensions, materials, shapes, relative arrangements, and the like of components are not intended to limit the scope of the present invention to them unless otherwise specified, and are merely illustrative examples.

1 is a perspective view of a fiber reinforced concrete cask according to an embodiment of the present invention, Figure 2 (a) is a cross-sectional view taken along the line AA of Figure 1, Figure 2 (b) of Figure 2 (a) 3 is a cross-sectional view along line BB, and FIG. 3 is a schematic view showing a manufacturing process of an embodiment of a fiber reinforced concrete cask according to the present invention.

This embodiment of a fiber reinforced concrete cask is used as a storage container for storing and transporting radioactive materials such as spent fuel and recycled fuel generated in a nuclear power plant.

1, 2 (a) and 2 (b), the fiber-reinforced concrete cask 10 according to the present invention includes an outer sheet 21 and an inner sheet 22 having a smaller diameter than this. It consists of a support frame 20 sewn into a cylindrical bag with a bottom, and concrete 11 filled in the support frame 20. Although not shown, it is configured to contain a radioactive material receiving canister. Further, the support frame 20 connects the inner circumferential surface of the outer sheet 21 and the outer circumferential surface of the inner sheet 22 with a plurality of strings 23 so as to maintain a predetermined shape.

In this configuration, reinforcing fibers are used for the outer sheet 21, the inner sheet 22, and the string 23. At least the outer sheet 21 of the reinforcing fibers is used a fiber having a coefficient of thermal expansion equal to or less than that of concrete. That is, for example, when filling the support frame 20 with concrete having a coefficient of thermal expansion of about 0.5 to 1.5 × 10 ⁻⁵ / ° C., the support frame 20 has a thermal expansion rate of about 1.5 × 10 ⁻⁵ / ° C. or less. Reinforcement fiber with As the reinforcing fiber, a fiber having a negative thermal expansion coefficient like carbon fiber and having high strength and heat resistance is preferable. Of course, it is preferable to use reinforcing fibers having the above-mentioned properties for the inner sheet 22 and the string 23.

Further, an injection port 12 is provided at the lower part of the support frame 20, and a fluid discharge port 13 is formed at the upper part of the support frame 20. The inlet 12 is configured to be connected to the supply hose of concrete injected into the support frame, and when the concrete is injected, the supply hose and the inlet 12 are sealed with a hose clamp.

On the other hand, it is preferable that the fluid outlet 13 is provided with a cock or another type of valve in order to facilitate the discharge of the support frame shape holding fluid described later and to keep the inside of the support frame closed by the valve. .

Furthermore, a plurality of strings 23 for maintaining the shape of the support frame 20 are arranged in the circumferential direction and the height direction of the support frame 20, so that the shape can be maintained even when concrete is filled in the support frame. There are as many as there are.

Furthermore, a flange 15 is formed on the upper inner circumferential surface of the concrete cask 10, so that the cover portion 14 can be fitted. The flange 15 is preferably formed as a convex portion filled with concrete 11 and formed on the inner circumferential surface of the inner sheet 22, and the lid portion 14 is reinforced like the support frame 20. It can be formed by filling the concrete 11 in a bag-shaped cover frame formed of fibers.

In addition, in this embodiment, although the concrete cask 10 is comprised by the one-piece hollow cylinder part with a bottom, it divides into three blocks of a hollow cylindrical body part, a disc bottom part, and a cover part, or many more blocks. Each of them can be manufactured separately and combined to form an integral concrete cask.

Furthermore, air supply and exhaust ports are formed on the side of the concrete cask 10 to supply and discharge air circulating in the space between the canister outer surface contained in the concrete cask 10 and the inner circumferential surface of the concrete cask 10. It is desirable to.

According to this structure, even if the concrete 11 is expanded by the heat generated in the canister, the support frame 20 having a smaller thermal expansion coefficient than the concrete 11 protects the concrete 11, thereby reducing the tension of the concrete. Weak but strong characteristics can be effectively used.

Furthermore, by using carbon fiber as the reinforcing fiber, it is possible to provide the concrete caster 10 excellent in strength and heat resistance.

Next, with reference to FIG. 3, the manufacturing method of the fiber reinforced concrete cask which concerns on a present Example is demonstrated.

First, as shown in Fig. 3A, the outer sheet and the inner sheet are sewn with reinforcing fibers such as carbon fiber. As the reinforcing fibers, as described above, fibers having a coefficient of thermal expansion equal to or less than that of concrete and having excellent strength and heat resistance are used. The reinforcing fiber sheets woven into the desired size, or rectangular sheet blocks of appropriate size, are stitched together to make a cylindrical sheet.

The inner sheet is made smaller in diameter by the thickness of the cask than the outer sheet. In addition, instead of sewing, reinforcing fibers may be bonded together by adhesion or welding. In addition, the outer circumferential surface of the inner sheet 22 and the inner circumferential surface of the outer sheet 21 are connected by a plurality of strings 23 made of reinforcing fibers. The bottom is formed, and the upper part of the sheet is connected to the annular reinforcing fiber sheet to produce a bag-shaped support frame.

And as shown in FIG.3 (b), the support frame shape holding fluid 16 is inject | poured from the injection hole 12 formed in the bottom of the said support frame 20. FIG. For easy operation, the fluid 16 should be easy to handle, such as air or water, have a smaller specific gravity than concrete, and have high separation from concrete. And, as shown in Fig. 3C, the support frame 20 filled with the fluid 16 is fixed by the fall prevention stay 26 to maintain its shape.

Next, the concrete 11 is injected by connecting a concrete supply pump to the inlet 12 as shown in FIG. At the same time, the valve of the fluid discharge port 13 provided in the upper part of the support frame 20 is opened, and the fluid 16 is discharged. Therefore, by injecting the concrete 11 from the bottom, the fluid having a small specific gravity is pushed out from the top, and replaced with the concrete 11 in the support frame 20 as shown in FIG. 3 (e).

Then, when the work of pouring concrete into the support frame 20 is completed, the injection of concrete is stopped, and the concrete is solidified for the required period. Thus, a cylindrical concrete cask in which the concrete 11 is solidified in the support frame 20 is produced.

According to this method, the construction can be simplified and the construction cost can be reduced, and a concrete cask excellent in heat resistance and strength can be manufactured.

In the case where water is used as the support frame shape holding fluid 16, it is preferable to use water-separated concrete having a very small material separation in the concrete 11.

As described above, according to the present invention, as in the prior art, the heat and heat resistance of the steel reinforcement or frame used in the cask is expanded or pulled by the heat generated in the contents of the cask, without the cracking or peeling of the reinforcement material. It is possible to manufacture this excellent concrete cask.

Moreover, by using a carbon fiber having a negative thermal expansion rate as the reinforcing fiber, such carbon fiber shrinks in response to a rise in temperature due to heat generated inside the cask to exert a compressive force on concrete (weak to tensile strength and strong against compressive force). Thus, the strength of the concrete can be significantly improved.

According to this invention, even if the pressure at the time of concrete injection remains as a tensile force in each sheet of the support frame, the sheet retracts conversely because the repulsive force from the concrete is lost after the concrete is cured, thereby giving compression prestress to the concrete from the outside. Concrete structures that are weak in tension but strong in compression can be effectively used.

That is, according to the present invention, it is possible to provide a concrete cask that can be easily constructed, can reduce construction costs, and is excellent in strength, durability, and heat resistance and can minimize the occurrence of cracks.

Claims (13)

At least on the outer circumferential surface of the concrete cask, a fiber reinforced concrete casing formed by injecting and solidifying concrete, characterized in that a support frame formed of a reinforced fiber sheet sewn in a cylindrical bag shape and having a thermal expansion rate smaller than that of concrete is disposed. Big. The fiber reinforcement of claim 1, wherein the reinforcing fiber sheet is disposed on both the outer and inner circumferential surfaces of the concrete cask, and the reinforcing fiber sheets on the outer and inner circumferential surfaces of the concrete cask are connected by a string. Concrete cask. The reinforcing fiber sheet sewn in a cylindrical bag shape is formed of a carbon fiber of a bag-shaped structure having a cylindrical shape including a hollow cylinder shape, a hollow cylinder with a bottom, and a solid cylinder including a bottom plate. Fiber reinforced concrete cask. A fiber-reinforced concrete cask having a thermal expansion rate smaller than that of concrete and formed by injecting and solidifying concrete into a support frame formed of a reinforced fiber sheet sewn into a cylindrical bag shape. The reinforcing fiber sheet sewn in a cylindrical bag shape is formed of a carbon fiber of a bag-shaped structure having a hollow cylinder shape, a hollow cylinder with a bottom, and a cylindrical shape including a solid cylinder as a bottom plate. Fiber reinforced concrete cask. A support frame for forming a concrete cask, which has a coefficient of thermal expansion smaller than that of concrete and is formed of a reinforced fiber sheet sewn into a cylindrical bag shape. The concrete casing according to claim 6, wherein the support frame has a double wall structure made of the reinforcing fiber sheet including the outer sheet and the inner sheet connected to each other, and the outer sheet and the inner sheet are connected by a string. Support frame for snap molding. 7. The support frame for forming a concrete cask according to claim 6, wherein the support frame has a concrete injection hole in a lower portion thereof. The support frame for forming a concrete cask according to claim 1, characterized in that the support frame has a concrete inlet at the bottom thereof. A step of forming a support frame for concrete injection, using a reinforcing fiber sheet sewn in a cylindrical bag shape and having a thermal expansion rate smaller than that of concrete, and Method of producing a concrete cask comprising the step of injecting concrete into the support frame. The method of manufacturing a concrete cask according to claim 10, wherein the support frame is made of a fiber reinforced sheet including an outer sheet and an inner sheet connected to each other by a reinforcing fiber string in the supporting frame forming process. 11. The method according to claim 10, wherein a step of filling the support frame shape holding fluid into the support frame is performed between the support frame forming step and the concrete injection step, and from the bottom of the support frame in the concrete injection step that is performed later. And injecting concrete to replace the fluid pre-filled in the support frame with concrete to maintain the shape of the support frame. The method of manufacturing a fiber reinforced concrete cask according to claim 10, wherein the concrete injection process is performed such that a tensile force is maintained on the reinforcing fiber sheet of the support frame from the pressure applied to the sheet during the injection process. .

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