Method for manufacturing radioactive waste solidified bodies and radioactive waste solidified bodies

Abstract

To provide a method for producing radioactive waste solidified matter that can suppress a pressure increase in a storage container even during curing of radioactive waste solidified matter.SOLUTION: A method for producing radioactive waste solidified matter which stores radioactive waste 11 in a storage container 10 and cures a solidified matter 13 solidified using mortar 12 includes: inserting a penetration cylinder 1 with a vent hole into the mortar 12 when the mortar 12 filled in the storage container 10 loses fluidity and starts to harden. After the mortar 12 is hardened, the penetration cylinder 1 may be removed from the mortar to form a through-hole in the solidified matter 13.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a solidified radioactive waste product and a solidified radioactive waste product that can suppress an increase in pressure inside a storage container even during the curing of the solidified radioactive waste product.

Background Art

[0002] Radioactive waste discharged from nuclear facilities is solidified using cement in storage containers such as drums and discarded as low-level radioactive waste. When high-level radioactive waste is solidified, the moisture contained in the solidified product is decomposed by radiation to generate hydrogen. Then, hydrogen accumulates in the solidified product over time, and since waste with a long storage time contains a large amount of hydrogen, it is necessary to suppress or prevent an increase in pressure inside the storage container during long-term burial disposal to ensure the soundness of the disposal site over a long period.

[0003] Patent Document 1 discloses a solidification treatment method for radioactive waste having a solidification step of kneading radioactive waste, a hydraulic inorganic solidifying material, and an aggregate, then supplying the mixture to a storage container to form a solidified product, a moisture removal step of removing moisture from the solidified product in the storage container by heating and / or decompression after curing the solidified product in the storage container, and a storage container sealing step of covering and sealing the storage container after the moisture removal step.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, even during the curing of the solidified radioactive waste product, hydrogen accumulates in the solidified product, resulting in an increase in pressure inside the storage container.

[0006] The present invention has been made in view of the above, and aims to provide a method for manufacturing a radioactive waste solidified body and a radioactive waste solidified body that can suppress the pressure rise inside the storage container even during the curing of the radioactive waste solidified body. [Means for solving the problem]

[0007] To solve the above-mentioned problems and achieve the objective, the present invention provides a method for manufacturing a radioactive waste solidified body obtained by solidifying radioactive waste stored in a storage container using mortar or concrete, characterized in that a rod-shaped body, through which gas can pass, is embedded in the mortar or concrete, and the mortar or concrete is cured.

[0008] Furthermore, the present invention is characterized in that, in the above invention, the rod-shaped body is removed from the mortar or concrete after the mortar or concrete has hardened to form a hole.

[0009] Furthermore, the present invention is characterized in that, in the above invention, the rod-shaped body has a cylindrical portion with ventilation holes formed around it and a conical portion with a cone-shaped tip.

[0010] Furthermore, the present invention relates to a radioactive waste solidification body comprising a storage container, radioactive waste stored in the storage container, and mortar or concrete for solidifying the radioactive waste inside the storage container, characterized in that it further comprises a rod-shaped body embedded in the mortar or concrete, through which gas can pass.

[0011] Furthermore, the present invention is characterized in that, in the above invention, the rod-shaped body has a cylindrical portion with ventilation holes formed around it and a conical portion with a cone-shaped tip. [Effects of the Invention]

[0012] According to the present invention, it is possible to suppress the rise in pressure inside the storage container even during the curing of solidified radioactive waste. [Brief explanation of the drawing]

[0013] [Figure 1] This diagram shows the configuration of a penetration cylinder, which is a rod-shaped body through which gas can pass, used in the method for manufacturing radioactive waste solidified bodies according to this embodiment. [Figure 2] This is an explanatory diagram illustrating a method for manufacturing radioactive waste solidified using a penetration cylinder. [Figure 3] This is a plan view showing the state in which the penetration cylinder has penetrated the solidified body. [Figure 4] This is a cross-sectional view showing the state in which a penetration cylinder has penetrated the solidified radioactive waste when the waste is in powder form. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments for carrying out the present invention will be described with reference to the attached drawings.

[0015] <Cracked Cylinder> Figure 1 shows the configuration of a penetration cylinder 1, which is a rod-shaped body through which gas can pass, used in the method for manufacturing a radioactive waste solidified body according to this embodiment. As shown in Figure 1, the penetration cylinder 1 has a cylindrical portion 2 with ventilation holes 4 formed around its periphery and a conical portion 3 with a cone-shaped tip.

[0016] <Method for manufacturing solidified radioactive waste> Figure 2 is an explanatory diagram illustrating a method for manufacturing a radioactive waste solidified body using a penetration cylinder 1. As shown in Figure 2, first, lump-shaped radioactive waste 11 such as rubble and pipes is placed in a storage container 10, and in this state, mortar 12 containing cement is filled into the storage container 10 (Figure 2(a)). In this embodiment, mortar 12 is used, but it is not limited to this, and concrete containing cement and aggregates such as sand may be used instead of mortar 12. Then, when the fluidity of the mortar 12 decreases and hardening begins, the penetration cylinder 1 is deeply inserted into the mortar 12 with the conical part 3 as its tip, and a part of the penetration cylinder 1 is embedded in the mortar 12 (Figure 2(b)). At this time, the other end of the penetration cylinder 1, which is located opposite the one end of the cylindrical part 2 connected to the conical part 3, is exposed from the mortar 12, and is not completely embedded in the mortar 12.

[0017] The reason why the penetration of the penetration cylinder 1 is defined as occurring when the fluidity of the mortar 12 decreases and hardening begins is that if the penetration occurs too early, the fluidity is high, and the mortar 12 enters the ventilation hole 4 of the penetration cylinder 1, blocking the ventilation hole 4. Conversely, if the penetration occurs too late, the hardening strength of the filled mortar 12 is high, requiring considerable effort to penetrate with the penetration cylinder 1. The specific timing of the start of hardening can be determined by inserting a rod such as the penetration cylinder 1 and then withdrawing it; if the hole into which the rod was inserted does not close within one minute, then the hardening has begun.

[0018] As a result, the hydrogen generated by the radioactive decomposition of water in the solidified body 13, which consists of mortar 12 and radioactive waste 11, is discharged from the solidified body 13 in the storage container 10 through the ventilation holes 4 and cylindrical section 2 opened in the penetration cylinder 1. Consequently, the hydrogen concentration in the solidified body 13 can be kept low for a long period of time, enabling long-term curing.

[0019] In addition, in this embodiment, after storing the massive radioactive waste 11 such as glass and pipes in the storage container 10, the storage container 10 was filled with mortar 12, and the step of piercing the penetration cylinder 1 into the mortar 12 was performed. However, the present invention is not limited to this, and after storing the massive radioactive waste 11 such as glass and pipes in the storage container 10 and arranging the penetration cylinder 1 in the storage container 10, the step of filling the storage container 10 with the mortar 12 may be performed. In the case of this step, since a part of the penetration cylinder 1 can be buried in the mortar 12 without moving the penetration cylinder 1, it is possible to suppress the ventilation holes 4 provided in the penetration cylinder 1 from being clogged with the mortar 12.

[0020] Note that FIG. 3 is a plan view showing a state where the penetration cylinder 1 is arranged in the solidified body. As shown in FIG. 3, the penetration cylinders 1 are arranged dispersedly and evenly with respect to the solidified body 13.

[0021] Also, in FIG. 2, it was the massive radioactive waste 11, but as shown in FIG. 4, it may be the powdery radioactive waste 21 generated by cutting or the like.

[0022] The penetration cylinder 1 may remain penetrated or may be removed after the solidified body has hardened. Even if the penetration cylinder 1 is removed, the generated hydrogen is released to the outside through the holes formed by the removal of the penetration cylinder 1.

[0023] For the penetration cylinder 1, a plastic-based material, aluminum, iron, stainless steel, or the like can be used. Since the plastic-based material and iron have low corrosion resistance, it is conceivable that if they are penetrated into the solidified body 13 for a long time, they will not be able to maintain the shape of the penetration cylinder 1 due to corrosion. However, since the solidified body 13 is solidified in a state having the through holes formed by the penetration cylinder 1, there is no problem even if the penetration cylinder 1 cannot maintain its shape due to corrosion.

[0024] Furthermore, the ventilation holes 4 may be porous in shape. For example, if the penetration cylinder 1 is made of metal, it may be made of a porous metal. This is because hydrogen is degassed through the connecting holes of the porous metal that constitutes the penetration cylinder 1. Therefore, the cylindrical portion 2 of the penetration cylinder 1 is not limited to a hollow cylindrical shape, but only needs to be able to allow gas to pass through. Also, the conical portion 3 of the penetration cylinder 1 makes it easier to penetrate the mortar 12 when the penetration cylinder 1 is inserted into the mortar 12. For this reason, when the penetration cylinder 1 is placed in the storage container 10 and then the mortar 12 is filled into the storage container 10 to form a solidified body 13, a penetration cylinder 1 consisting only of a cylindrical portion 2 without a conical portion 3 may be used.

[0025] Furthermore, the configurations illustrated in the above embodiments are functionally schematic and do not necessarily have to be physically represented as shown. In other words, the forms of distribution and integration of each device and component are not limited to those shown, and all or part of them can be functionally or physically distributed and integrated in any unit according to various usage situations. [Explanation of Symbols]

[0026] 1. Penetration cylinder 2 Cylinder part 3. Pyramidal region 4. Ventilation holes 10 Storage containers 11,21 Radioactive waste 12 Mortar 13. Solidified body

Claims

1. A method for manufacturing a radioactive waste solidified body, which is obtained by solidifying radioactive waste stored in a storage container using mortar or concrete, The process includes arranging a rod-shaped body, through which gas can pass, embedded in the mortar or concrete, and curing the mortar or concrete. A method for manufacturing a radioactive waste solidified body, characterized in that the rod-shaped body has a cylindrical portion with ventilation holes formed around its periphery and a conical portion with a cone-shaped tip.

2. A method for producing a radioactive waste solidified body obtained by solidifying radioactive waste stored in a storage container using mortar or concrete, The process includes arranging a rod-shaped body, through which gas can pass, with at least its lower part embedded in the mortar or concrete, and curing the mortar or concrete. The rod-shaped body has a cylindrical portion with ventilation holes formed around it, A method for manufacturing a radioactive waste solidification body, characterized in that the cylindrical portion is arranged embedded in the mortar or concrete so that gas that enters the interior of the cylindrical portion from the mortar or concrete through the ventilation holes can be discharged to the outside through an opening at the upper end of the cylindrical portion.

3. A method for producing a radioactive waste solidified body according to claim 1 or 2, characterized in that the rod-shaped body is removed from the mortar or concrete after the mortar or concrete has hardened to form a hole.

4. Storage containers and The radioactive waste stored in the aforementioned storage container, Mortar or concrete for solidifying the radioactive waste inside the storage container, A radioactive waste solidified body having, The aforementioned mortar or concrete further comprises a rod-shaped body through which gas can pass, The aforementioned rod-shaped body is characterized by having a cylindrical portion with ventilation holes formed around its periphery and a conical portion with a cone-shaped tip.

5. A storage container and The radioactive waste stored in the aforementioned storage container, Mortar or concrete for solidifying the radioactive waste inside the storage container, A radioactive waste solidified body having, The present invention further comprises a rod-shaped body, at least its lower part embedded in the mortar or concrete, through which gas can pass. The rod-shaped body has a cylindrical portion with ventilation holes formed around it, The radioactive waste solidification body is characterized in that the cylindrical portion is arranged in a state embedded in the mortar or concrete so that gas that enters the interior of the cylindrical portion from the mortar or concrete through the ventilation holes can be discharged to the outside through an opening at the upper end of the cylindrical portion.

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