JP4340974B2 - Waste disposal method - Google Patents

Description

  The present invention relates to a waste embedding disposal method for embedding a waste body made of, for example, radioactive waste.

  High-level radioactive waste must be buried and disposed of deep underground. For example, waste liquid with a high radioactive level is solidified with glass, and the solidified glass solidified body is stored in a container (overpack) such as carbon steel, and this glass solidified body is stored in the container (hereinafter referred to as waste body). It is obliged to be buried in a stratum deeper than 300m underground.

  As a method of disposing of waste in the ground, a disposal tunnel is dug up to a predetermined level in the ground, a disposal hole is drilled in the bottom of the disposal tunnel, and the waste is put in the disposal hole, and then the disposal tunnel The method of backfilling (disposing hole disposal method) is common. At this time, corrosion of the overpack is accelerated by the spring water in the disposal hole, and the period during which the vitrified body can be sealed may be shortened. It is installed (for example, refer to Patent Document 1).

  The buffer material installed in the disposal hole is often made of bentonite-based material, and the bentonite-based material has the property that it swells with water, so if the spring water that springs from the ground enters the disposal hole, the buffer material swells. It is possible to bulge into the disposal tunnel. Since it is necessary to ensure the density of the buffer material from the viewpoint of disposal performance, the expansion of the buffer material must be suppressed at least until the disposal tunnel is backfilled.

  As a method for suppressing the swelling of the cushioning material, after the cushioning material is installed in the disposal hole, a concrete cap is temporarily placed at the hole of the disposal hole to resist the swelling stress of the cushioning material. . The cap can be fixed by fastening it to a lock bolt placed in the disposal tunnel (lock bolt method) or by pressing it with a support member supported by a reaction force from the wall of the disposal tunnel. A method of fixing with a tunnel (support method for tunnel top) is conceivable.

On the other hand, conventionally, there has been provided a method of blocking the spring water to suppress the swelling of the buffer material and ensure the density of the buffer material. This method is a method in which a waste body covered with a buffer material is stored in a cylindrical water shielding container made of a steel plate or the like, and is disposed in a disposal hole. According to this method, since the intrusion of spring water is prevented by the water shielding container, the buffer material does not swell and the density of the buffer material can be ensured (for example, refer to Patent Document 2).
Japanese Patent Laid-Open No. 5-203797 JP 2004-286451 A

However, in the above-described conventional method of suppressing the expansion of the buffer material with the cap made of concrete, the concrete that is the material of the cap, the bedrock around the disposal site due to the high pH and high Ca environment due to the dissolution of the hydrated cement, There is a problem that the buffer material made of bentonite-based material is dissolved and altered, which may greatly affect the disposal performance.
In addition, if the lock bolt method is used as a method of fixing the cap, it resists the swelling stress of the cushioning material, which requires a lot of lock bolts, which increases the cost. There is a problem of damage.
In addition, when the tunnel top support system is used as a method for fixing the cap, the support material assembled using the space in the disposal tunnel becomes an obstacle to the subsequent placement work and backfilling work, and the workability of the work is improved. There is a problem that decreases. Moreover, if the disposal tunnel is backfilled while removing the support material, it is expected that the swelling of the buffer material cannot be suppressed, and there is a problem that the feasibility remains in the fixing method using the tunnel roof support system.
Furthermore, from the viewpoint of the global environment, it is desirable that a small amount of waste be buried in the ground. However, in the conventional method of storing waste covered with a buffer material in a water shielding container, water shielding Since the vessel is made of steel, etc., even after the disposal tunnel is backfilled and the cushioning material cannot swell, the impermeable container remains in the ground and is buried in the ground There is a problem of increasing the amount.

  The present invention takes the above-described conventional problems into consideration, and suppresses swelling of the buffer material without reducing workability such as backfilling and without increasing the amount of material buried in the ground. In addition, the object is to provide a method for burying and disposing of waste that can reduce the cost without causing damage to the surrounding rock mass.

  According to the first aspect of the present invention, a disposal hole is drilled in a bottom surface or a wall surface of a cavity formed in the ground, a waste body is disposed in the disposal hole, and the waste body is covered with a cushioning material, and thereafter In the waste embedding disposal method for refilling the cavity, the buffer material is covered with an outer shell material made of biodegradable plastic having a water shielding performance.

  With such a feature, the spring water from the inner surface of the disposal hole is blocked by the outer shell material, and the buffer material is prevented from swelling by the spring water. In addition, the outer shell made of biodegradable plastic blocks the intrusion of spring water for a certain period of time after installation, and is decomposed by microorganisms in the soil and water after a certain period of time, eventually becoming water and carbon dioxide. .

  According to the waste embedding disposal method according to the present invention, the buffer material is prevented from swelling by the spring water by covering the buffer material with the outer shell material made of biodegradable plastic having a water shielding performance. Therefore, workability such as backfilling is not deteriorated, the surrounding rock mass is not damaged, and swelling suppression of the buffer material can be realized at low cost. The outer shell material is made of biodegradable plastic and is decomposed by microorganisms in the soil and water after a certain period of time. It is possible to reduce the possibility of affecting the process.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a waste embedding disposal method according to the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a situation in which waste is buried. Reference numeral 1 shown in FIG. 1 is a disposal mine excavated in a stratum (rock) deeper than 300 m underground, and a cylindrical disposal hole 2 for accommodating the waste body 3 is drilled in the bottom surface of the disposal mine 1. Has been. A plurality of disposal holes 2 (one in FIG. 1) are disposed on the bottom surface of the disposal mine 1. In each disposal hole 2, a waste body 3, a buffer material 4 that covers the periphery of the waste body, and an outer shell material 5 that covers the periphery of the buffer material 4 are stored.

The waste body 3 is obtained by solidifying a waste liquid having a high radioactive level with glass and storing the glass solid body in an overpack such as carbon steel.
The buffer material 4 is composed of a plurality of disk-shaped blocks 6 made of bentonite-based material, and the cylindrical buffer material 4 is formed by laminating these blocks 6. A space for storing the waste body 3 is formed in the central portion of the cushioning material 4, and the block 6 a that forms this space is annular.

  The outer shell material 5 is a member made of biodegradable plastic having a water shielding performance interposed between the inner surface of the disposal hole 2 and the buffer material 4, and a cylindrical portion 7 that covers the outer peripheral surface of the buffer material 4; The bottom plate 8 covers the lower end surface of the cushioning material 4 and the top plate 9 covers the upper end surface of the cushioning material 4. The outer shell material 5 is formed in a cylindrical box shape in which the lower end portion of the cylindrical portion 7 is closed by the bottom plate portion 8 and the upper end portion of the cylindrical portion 7 is closed by the top plate portion 9. Between the lower end part of the cylinder part 7 and the bottom plate part 8, and between the upper end part of the cylinder part 7 and the top plate part 9, a water-stopping property is ensured by a sealing process, etc. It is formed so that water does not enter inside.

Next, a method for burying the waste body 3 will be described.
First, a drilling process is performed in which the disposal tunnel 1 is excavated in the ground by a well-known excavation method, and a plurality of disposal holes 2 are drilled in the bottom surface thereof.

Next, the waste body 3 is installed in the disposal hole 2, and the installation process of covering the waste body 3 with the buffer material 4 and further covering the buffer material 4 with the outer shell material 5 is performed.
Specifically, the cylindrical portion 7 and the bottom plate portion 8 are bonded in advance, and a sealing process is performed on the bonded portion to form a bottomed cylindrical container 10. Then, the blocks 6 are stacked in the container 10, the waste body 3 is stored in the annular block 6 a, and the blocks 6 are stacked up to the upper end of the container 10 to form the cushioning material 4. Then, the top plate part 9 is put on and joined to the upper end part of the cylinder part 7, and a sealing process is applied to the joining part.
Next, the outer shell material 5 in which the waste body 3 and the buffer material 4 are accommodated is inserted from the hole 2 a of the disposal hole 2 and installed in the disposal hole 2.
At this time, the type of biodegradable plastic forming the outer shell material 5 is selected based on the time from when the outer shell material 5 is installed in the disposal hole 2 to the backfilling of the disposal tunnel 1, and at least A kind of biodegradable plastic that can exhibit water shielding performance without being decomposed for a longer time than the above time is selected.

  Subsequently, after performing the installation process mentioned above about the some disposal hole 2 formed in the disposal tunnel 1, the backfilling process which backfills the disposal tunnel 1 is performed, and the disposal disposal of the waste body 3 is completed.

  According to the waste embedding disposal method having the above-described configuration, the buffer material 4 is swollen by the spring water by covering the buffer material 4 with the outer shell material 5 made of biodegradable plastic having a water shielding performance. It is prevented. As a result, workability such as backfilling is not deteriorated, the surrounding rock mass is not damaged, and swelling suppression of the buffer material 4 can be realized at low cost. In addition, the outer shell material 5 is made of biodegradable plastic and exhibits water shielding performance until before backfilling, and is decomposed by microorganisms in the soil and water after backfilling. The outer shell material 5 does not remain in the ground. As a result, the amount of material buried in the ground is not increased, and it is environmentally friendly, and the possibility of affecting the disposal performance can be reduced.

  As mentioned above, although embodiment of the waste embedding disposal method concerning this invention was described, this invention is not limited to above-described embodiment, In the range which does not deviate from the meaning, it can change suitably. For example, in the above-described embodiment, the outer shell material 5 is formed in a cylindrical box shape, and after the waste body 3 and the buffer material 4 are respectively stored in the outer shell material 5, the outer shell material 5. However, in the present invention, the outer shell material pasted around the cushioning material may be inserted into the disposal hole, and the outer surface of the disposal hole may be inserted into the disposal hole. After pasting the shell material, the waste covered with the buffer material may be accommodated therein.

  Further, in the above-described embodiment, the buffer material 4 is formed by stacking the blocks 6 made of bentonite-based material. However, the present invention can be applied to the disposal hole or the container in which the outer shell material is adhered to the inner surface. It may be a cushioning material configured to fill and compact a bentonite-based material in a shell-like outer shell material, or may be a container-shaped cushioning material that stores waste.

In the above-described embodiment, an example in which the disposal hole 2 is drilled in the pit-like cavity like the disposal tunnel 1 has been described. However, the present invention only needs to be a cavity formed in the ground. A disposal hole may be drilled in a cavity formed in a chamber shape.
In the above-described embodiment, the disposal hole 2 is drilled on the bottom surface of the disposal tunnel 1, but in the present invention, the disposal hole may be drilled on the wall surface of the disposal tunnel.
Further, in the above-described embodiment, the disposal hole 2 is drilled in a cylindrical shape. However, in the present invention, the disposal hole may be drilled in a polygonal column shape such as a square column, or any other shape. .
In the above-described embodiment, waste liquid with a high radioactive level is solidified with glass, and the glass solidified body is stored in an overpack such as carbon steel as waste body 3, but the present invention has any configuration. It may be a waste body, for example, a waste body in which liquid waste is solidified with a substance other than glass and stored in an overpack, or a waste body in which solid waste is stored in an overpack. Furthermore, it does not have to be a radioactive waste, and any waste may be applied to the present invention as a waste.

It is sectional drawing for demonstrating embodiment of the waste burying disposal method concerning this invention.

Explanation of symbols

1 disposal tunnel (cavity)
2 Disposal hole 3 Waste 4 Buffer material 5 Shell material

Claims (1)

Waste that has a disposal hole drilled in the bottom or wall surface of the cavity formed in the ground, places the waste in the disposal hole, covers the waste with a buffer, and then refills the cavity In the landfill disposal method,
A waste burying / disposal method characterized in that the buffer material is covered with an outer shell material made of biodegradable plastic having water shielding performance.

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