KR102458248B1 - Construction method of buffer material at field - Google Patents

Abstract

The present invention relates to a method for on-site construction of a cushioning material. Specifically, according to an embodiment of the present invention, there is provided a buffer material on-site construction method capable of constructing a buffer material in a disposal hole of a high-level waste repository, the method comprising: a pouring step of pouring a buffer material into the disposal hole; a pressing step of forming a buffer layer having a predetermined thickness by pressing the buffer material poured into the disposal hole at a predetermined pressure; and a physical property acquisition step of acquiring the physical properties of the buffer layer, wherein if the obtained physical properties of the buffer layer fall within a preset predetermined range, the pouring step, the pressing step, and the physical property acquisition to form another buffer layer on the buffer layer A method for in situ construction of a cushioning material may be provided, in which the steps are performed.

Description

CONSTRUCTION METHOD OF BUFFER MATERIAL AT FIELD

The present invention relates to a method for on-site construction of a cushioning material.

In general, high-level radioactive waste separated from spent nuclear fuel is a material with high radiation intensity. These high-level wastes need to be stored to minimize damage to people and the environment in the process of disposal. Accordingly, high-level waste is stored at a depth of several hundred meters underground so that the time it takes for the nuclide to move through the medium such as the ground and be exposed to the human lifesphere is tens of thousands of years or more when the nuclide is leaked, and it remains in the disposal container for a long period of time. kept while

Referring to FIG. 1 , a conventional high-level high-level waste repository in which high-level waste is stored forms a disposal hole in advance (rock excavation), and inserts a buffer block into the disposal hole. Thereafter, after inserting the disposal container in which the high-level waste is accommodated between the buffer blocks, a buffer block is additionally inserted to surround the perimeter of the disposal container. As such, the cushioning material block is inserted into the disposal well to surround the disposal vessel but face the inner wall of the disposal well.

However, in order to use the buffer block in the disposal well, it is molded into a predetermined shape and then stored for a certain period in a dedicated storage facility. Due to this, a considerable budget is required to produce cushioning blocks larger than the engineering scale. In addition, the size of the buffer block designed to fit the size of the disposal hole may not exactly fit the actual disposal hole. This is because, when the cushioning material block is manufactured in an indoor facility and transferred to a repository, the cushioning material block may be easily deformed due to stress release and changes in humidity during the transportation process. For this reason, a gap is formed between the inner wall of the disposal hole and the buffer block, or the buffer block cannot enter the disposal hole at all. As such, when a gap is formed in the buffer block, groundwater can rapidly flow in and accelerate the corrosion of the disposal container, which in turn improves the possibility of nuclide leakage.

However, in order to fill this gap, various attempts (development of a dedicated gap filling material, etc.) have been made recently. However, if the gap is filled after arranging the cushioning material block, the cushioning material block is more likely to be damaged, and economic efficiency and workability are significantly reduced.

Therefore, when disposing the disposal container in the disposal hole, it is necessary to develop a technology for a cushioning material installation method with excellent quality control and constructability while surrounding the disposal container without forming a gap with the disposal hole.

Embodiments of the present invention were invented based on the above background, and when disposing a disposal container in a disposal hole, it is intended to provide a method for constructing a buffer material on-site that surrounds the disposal container but does not form a gap with the disposal hole.

In addition, by measuring the quality of the cushioning material in real time, it is intended to provide a cushioning material site construction method that can fill the disposal hole while ensuring the quality of the cushioning material.

According to an aspect of the present invention, there is provided a buffer material on-site construction method capable of constructing a buffer material in a disposal hole of a high-level waste repository, the method comprising: a pouring step of pouring a buffer material into the disposal hole; a pressing step of forming a buffer layer having a predetermined thickness by pressing the buffer material poured into the disposal hole at a predetermined pressure; and a physical property acquisition step of acquiring the physical properties of the buffer layer, wherein if the obtained physical properties of the buffer layer fall within a preset predetermined range, the pouring step, the pressing step, and the physical property acquisition to form another buffer layer on the buffer layer A method for in situ construction of a cushioning material may be provided, in which the steps are performed.

In addition, the physical property acquisition step may include: a dry density acquisition step of acquiring a dry density of the buffer layer; and a water content obtaining step of obtaining the water content of the buffer layer, a buffer material site construction method may be provided.

In addition, when the dry density falls within the range of 1.6 g/cm 3 or more and 1.8 g/cm 3 or less, the pouring step, the pressing step and the physical property acquisition step are performed to form another buffer layer on the buffer layer, buffer material field construction A method may be provided.

In addition, the buffer layer is in contact with the inner peripheral surface of the disposal hole, sealing the gap between the buffer layer and the disposal hole, a buffer material on-site construction method may be provided.

In addition, the cushioning material, including bentonite pellets, a cushioning material field construction method may be provided.

In addition, the bentonite pellets, having a diameter of 5mm or more and 15mm or less, a cushioning material field construction method may be provided.

In addition, in the pressing step, the buffer material is pressurized to a pressure of 50Mpa or more and 180Mpa or less, a buffer material field construction method may be provided.

In addition, the buffer layer pressurized in the pressing step has a thickness of 20 cm or more and 60 cm or less, a buffer material on-site construction method may be provided.

According to embodiments of the present invention, when disposing the disposal container in the disposal hole, there is an effect that surrounds the disposal container, but does not form a gap with the disposal hole.

In addition, by measuring the quality of the cushioning material in real time, there is an effect that can fill the disposal hole while ensuring the quality of the cushioning material.

1 is a diagram illustrating a gap between a buffer block surrounding a disposal vessel and an inner surface of a disposal well;
Figure 2 is a flow chart schematically showing a buffer material site construction method according to an embodiment of the present invention.
Figure 3 is a view conceptually showing the construction process of the cushioning material site.
Figure 4 is a view conceptually showing the construction process of the cushioning material site.

Hereinafter, specific embodiments for implementing the spirit of the present invention will be described in detail with reference to the drawings.

In addition, in the description of the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In addition, when it is stated that a component is 'attached', 'adhered', or 'contacted' to another component, it may be directly attached, adhered to, or contacted with the other component, but other components may exist in between. will have to be understood

The terminology used herein is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise.

Also, terms including an ordinal number such as 1st, 2nd, etc. may be used to describe various components, but the components are not limited by these terms. These terms are used only for the purpose of distinguishing one component from another.

The meaning of "comprising," as used herein, specifies a particular characteristic, region, integer, step, operation, element and/or component, and other specific characteristic, region, integer, step, operation, element, component, and/or group. It does not exclude the existence or addition of

In addition, in the present specification, the expressions of the upper surface, the lower surface, the upper side, the lower side, etc. are described with reference to the drawings in the drawings, and it is clarified in advance that if the direction of the corresponding object is changed, it may be expressed differently. Meanwhile, in the present specification, the vertical direction may be the vertical direction of FIGS. 3 and 4 .

Hereinafter, with reference to the drawings, a detailed configuration of the cushioning material field construction method (S10) according to an embodiment of the present invention will be described.

Hereinafter, referring to FIG. 2 , the buffer material on-site construction method ( S10 ) according to an embodiment of the present invention constructs a buffer material on-site without the need to pre-fabricate a buffer material block in order to surround the disposal container 3 in which the high-level waste is accommodated can do. Here, the site may mean, for example, the deep geological high-level waste repository 1 , and constructing the buffer material on site may be understood as constructing the buffer material within the disposal hole 2 of the repository. In addition, the cushioning material may be understood as a buffer layer 400 to be described later. The disposal hole 2 may be formed in advance in the deep geological high-level waste repository 1 , and may be formed by, for example, a Reverse Raise Boring (RRS) method. The buffer material site construction method (S10) may include a drying step (S100), a pouring step (S200), a pressing step (S300), and a physical property acquisition step (S400).

In the drying step S100 , the disposal hole 2 may be dried in order to secure workability within the disposal hole 2 . For example, in the drying step S100 , the fluid remaining in the disposal hole 2 may be transferred to the outside of the disposal hole 2 through the drainage pump 110 installed in the mobile dedicated facility 100 . In addition, the disposal hole 2 can be maintained in a dry state by injecting the compressed gas into the disposal hole 2 . In addition, when the disposal hole 2 is in a dry state in the drying step S100 , the electrode 200 may be installed on the bottom of the disposal hole 2 .

In the pouring step (S200), the buffer material 300 may be poured into the disposal hole (2). In other words, in the pouring step (S200), it is possible to pour a predetermined amount of the buffer material 300 on the bottom of the disposal hole (2). For example, the cushioning material 300 may include bentonite pellets. As a more detailed example, the bentonite pellets may have a diameter of 5 mm or more and 15 mm or less. The buffer material 300 to be poured into the disposal hole 2 covers the bottom of the disposal hole 2 , and a sufficient amount to have a predetermined thickness may be supplied to the disposal hole 2 .

In the pressing step ( S300 ), the buffer layer 400 having a predetermined thickness may be formed by pressing the buffer material 300 poured into the disposal hole 2 at a predetermined pressure. This pressing step (S300) may be made by the press 120 installed in the mobile dedicated facility (100). For example, the press 120 may press the cushioning material 300 at a pressure of 50 Mpa or more and 180 Mpa or less. At this time, the buffer layer 400 formed by pressing the buffer material 300 by the press 120 may have a thickness of 14 cm or more and 60 cm or less. As such, the pressure at which the press 120 presses the cushioning material 300 may vary depending on the size of the disposal hole 2 . In addition, the thickness of the buffer layer 400 formed by being pressed by the press 120 may also be different depending on the mineral composition and water content of the buffer material 300 .

As a more detailed example, the buffer layer 400 may be a buffer block formed by pressing the buffer material 300 . The buffer layer 400 is deformed in shape by the pressure applied to the plurality of bentonite pellets, and thus may be formed by reducing voids between the plurality of bentonite pellets. Accordingly, the buffer layer 400 is formed by pressing bentonite pellets, and may be understood as a bentonite block having a high density. In addition, since the buffer layer 400 is formed by being pressed by the press 120 from the upper side, it can be in close contact with the inner surface of the disposal hole (2). Also, the buffer layer 400 may seal a gap between the buffer layer 400 and the disposal hole 2 .

In the physical property acquisition step S400 , it may be determined whether the buffer layer 400 is within acceptable quality by acquiring the physical properties of the buffer layer 400 . For example, if the physical properties of the buffer layer 400 obtained in the physical property acquisition step ( S400 ) fall within a preset predetermined range, the pouring step ( S200 ), the pressing step to form another buffer layer 400 on the buffer layer 400 . (S300) and the physical property acquisition step (S400) may be performed again.

In the physical property acquisition step S400 , the dry density and water content of the buffer layer 400 may be obtained by measuring the resistance of the buffer layer 400 . The physical property acquisition step S400 may include a resistance measurement step S410 , a water content acquisition step S420 , and a dry density acquisition step S430 .

In the resistance measurement step S410 , the resistance of the buffer layer 400 may be measured through the electrode 100 . A plurality of such electrodes 100 may be provided, one of the plurality of electrodes 100 may be attached to one side of the buffer layer 400 , and the other of the plurality of electrodes 100 may be the other side of the buffer layer 400 . can be attached to For example, in the resistance measurement step S410 , the electrode 100 is attached to the upper and lower surfaces of the buffer layer 400 , so that the resistance of the buffer layer 400 in the vertical direction can be measured.

In the water content obtaining step S420 , the electrical resistivity of the buffer layer 400 may be obtained using the resistance of the buffer layer 400 measured in the resistance measuring step S410 . In addition, in the water content obtaining step ( S420 ), the water content of the buffer layer 400 may be obtained through the obtained electrical resistivity and the following [Equation 1] to [Equation 3].

[Formula 1]

(Ф is the pore ratio of the sample, ρ _w is the electrical resistivity of the fluid flowing into the sample, ρ _s is the electrical resistivity of the sample, a, m, n are the constants, and S is the saturation)

[Equation 2]

(γ _v is the density of the sample, ρ _w is the electrical resistivity of the fluid flowing into the sample, Ф is the pore ratio of the sample, and G _s is the specific gravity of particles in the sample)

[Equation 3]

(w is the water content of the sample, Ф is the pore ratio of the sample, S is the saturation of the sample, and G _s is the specific gravity of the particles in the sample.)

If the water content obtained in this water content acquisition step (S420) falls within the range of 10% or more and 18% or less, pouring step (S200), pressing step (S300) and The physical property acquisition step ( S400 ) may be performed again.

In the dry density obtaining step S430 , the dry density of the buffer layer 400 may be obtained. In addition, if the dry density of the buffer layer 400 obtained in the dry density acquisition step (S430) is within the range of 1.6 g/cm ³ or more and 1.8 g/cm ³ or less, another buffer layer 400 is formed on the buffer layer 400. The pouring step (S200), the pressing step (S300) and the physical property acquisition step (S400) to form may be performed again.

Hereinafter, the action and effect of the cushioning material field construction method (1) having the configuration as described above will be described.

A user may form a disposal hole (2) in the deep geological high-level waste repository (1). When the disposal hole 2 is formed, the disposal hole 2 may be made in a dry state by removing the groundwater in the disposal hole 2 (see FIG. 3(a) ).

Thereafter, after the electrode 200 is installed on the bottom of the disposal hole 2 , the buffer material 300 may be poured into the disposal hole 2 . At this time, the buffer material 300 may cover the bottom of the disposal hole 2, and a sufficient amount to have a predetermined thickness may be supplied to the disposal hole 2 (refer to FIG. 3(b) ).

When the cushioning material 300 is poured into the disposal hole 2 , the press 120 may press the cushioning material 300 from the top toward the floor. As such, the buffer layer 400 may be formed by the press 120 pressing the buffer material 300 . The press 120 may press the buffer layer 400 with a predetermined pressure so that the physical properties of the buffer layer 400 fall within an allowable range (refer to FIG. 3(c) ).

When the buffer layer 400 is formed, the electrode 200 may be installed on the upper surface of the buffer layer 400 to measure the resistance of the buffer layer 400 in the vertical direction (refer to FIG. 3(d) ). In this case, the measured resistance may be used to obtain the electrical resistivity of the buffer layer 400 . In addition, when the electrical resistivity of the buffer layer 400 is obtained, the water content of the buffer layer 400 can be obtained, and the dry density of the buffer layer 400 can be obtained.

As such, when the water content and dry density of the buffer layer 400 do not fall within a predetermined range, the pressing step S300 may be performed again.

On the other hand, when the water content and dry density of the buffer layer 400 are within a predetermined range, the pouring step (S200), the pressing step (S300), and the physical property acquisition step (S400) to form another buffer layer 400 on the buffer layer 400 ) can be performed again.

In the pouring step (S200) performed later, the buffer material 300 may be poured on the upper surface of the buffer layer 400 (see FIG. 4(a)).

In addition, when the buffer material 300 is poured on the upper surface of the buffer layer 400 , the press 120 may press the buffer material 300 poured on the upper surface of the buffer layer 400 . As such, another buffer layer 400 may be formed on the upper surface of the buffer layer 400 . Here, the buffer layer 400 disposed on the bottom surface may be referred to as the first buffer layer 400 , and the other buffer layer 400 may be referred to as the second buffer layer 400 (see FIG. 4(b) ).

Thereafter, it is possible to determine whether the second buffer layer 400 is within acceptable quality by acquiring the physical properties of the second buffer layer 400 (refer to FIG. 4(c) ). For example, if the physical properties of the second buffer layer 400 are within a predetermined range, the pouring step ( S200 ), the pressing step ( S300 ) and the physical properties to form another buffer layer 400 on the second buffer layer 400 . The acquiring step ( S400 ) may be performed again.

On the other hand, when the buffer layer 400 is stacked to a predetermined height of the disposal hole 2 , the disposal container 3 accommodating the high-level waste may be disposed inside the disposal hole 2 . Thereafter, the buffer material 300 may be poured to surround the disposal container 3 , and the buffer layer 400 may be formed by pressing.

In addition, by repeatedly performing the pouring step (S200), the pressing step (S300), and the physical property acquisition step (S400), the buffer layer 400 is formed so that the buffer layer 400 surrounds the disposal container 3 in the disposal hole 2 . can be formed (see Fig. 4(d)).

As such, since the buffer layer 400 is disposed to surround the disposal container 3 , it is possible to prevent leakage of nuclides from the high-level waste.

In addition, instead of placing the block formed by pressing the buffer material 300 in the disposal hole 2 , the buffer layer 400 is formed by pouring the buffer material 300 into the disposal hole 2 on site and then pressing it. By doing so, there is an effect that the buffer layer 400 and the inner surface of the disposal hole 2 are in close contact.

In addition, the buffer layer 400 formed by pressing the buffer material 300 seals the gap between the inner surface of the disposal hole 2 and the buffer layer 400 between the buffer layer 400 and the inner surface of the disposal hole 2 . It has the effect of preventing the inflow of groundwater.

Although the embodiments of the present invention have been described as specific embodiments, these are merely examples, and the present invention is not limited thereto, and should be construed as having the widest scope according to the basic idea disclosed in the present specification. A person skilled in the art may implement a pattern of a shape not specified by combining/substituting the disclosed embodiments, without departing from the scope of the present invention. In addition, those skilled in the art can easily change or modify the disclosed embodiments based on the present specification, and it is clear that such changes or modifications also fall within the scope of the present invention.

1: High-level waste repository 2: Disposer
3: disposal vessel 100: mobile dedicated facility
110: drain pump 120: press
200: electrode 300: buffer material
400: buffer layer

Claims (8)

In the buffer material site construction method that can construct the buffer material in the disposal hole of the high-level waste repository,
a pouring step of pouring a buffer material into the disposal hole;
a pressing step of forming a buffer layer having a predetermined thickness by pressing the buffer material poured into the disposal hole at a predetermined pressure; and
It is carried out after the pressing step, comprising a physical property acquisition step of acquiring the physical properties of the buffer layer,
If the obtained physical properties of the buffer layer fall within a predetermined range, the pouring step, the pressing step and the physical property obtaining step are performed to form another buffer layer on the buffer layer,
If the obtained physical properties of the buffer layer do not fall within the predetermined range, the pressing step is performed again to press the buffer layer to a predetermined pressure,
The physical property acquisition step is,
a resistance measuring step of measuring the resistance of the buffer layer through an electrode;
a water content obtaining step of obtaining an electrical resistivity of the buffer layer based on the resistance of the buffer layer measured in the resistance measuring step, and obtaining a water content based on the obtained electrical resistivity of the buffer layer; and
Comprising a dry density obtaining step of obtaining the dry density of the buffer layer,
When the obtained water content of the buffer layer falls within the range of 10% or more and 18% or less, the pouring step, the pressing step and the physical property acquisition step are performed to form another buffer layer on the buffer layer,
How to install cushioning material on site. delete The method of claim 1,
When the dry density is within the range of 1.6 g/cm ³ or more and 1.8 g/cm ³ or less, the pouring step, the pressing step and the physical property acquisition step are performed to form another buffer layer on the buffer layer,
How to install cushioning material on site. The method of claim 1,
The buffer layer is in contact with the inner surface of the disposal hole, thereby sealing the gap between the buffer layer and the disposal hole,
How to install cushioning material on site. The method of claim 1,
The cushioning material comprises bentonite pellets,
How to install cushioning material on site. 6. The method of claim 5,
The bentonite pellets have a diameter of 5 mm or more and 15 mm or less,
How to install cushioning material on site. The method of claim 1,
In the pressing step, the buffer material is pressurized to a pressure of 50Mpa or more and 180Mpa or less,
How to install cushioning material on site. 7. The method of claim 6,
The buffer layer pressurized in the pressing step has a thickness of 14 cm or more and 60 cm or less,
How to install cushioning material on site.

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