JP2003043192A - Disposal tunnel of layer disposal facility and filling cushioning material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disposal tunnel of a layer disposal facility and a filling cushioning material capable of reducing a construction cost by reducing the whole underground facility part by increasing disposal density of wastes, and relieving a restriction condition to base rock being a proper place. SOLUTION: In this disposal tunnel of the layer disposal facility, a sealing bodies filled with the wastes are buried on the periphery by interposing a cushioning material 21, and it is characterized in that the cushioning material of an interposing brick 22 is composed of a low water permeable material, and an oxidizing agent 23 is mixed in, and solves a problem caused by a flow of underground water and corrosion of a waste container by excluding and reducing a corrosion factor such as oxygen before the underground water reduced in quantity by reducing a flow speed reaches the wastes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disposal tunnel and a filling buffer material for a geological disposal facility, and more particularly to a geological disposal facility that can reduce the corrosion progress rate of a waste container and suppress the elution of radioactive substances to safely dispose of it. Of disposal tunnels and filling cushions.

[0002]

2. Description of the Related Art A nuclear fuel cycle centered on a nuclear power plant is constructed such that spent fuel is transferred to a reprocessing plant and uranium and plutonium are recovered and processed into fuel for reuse. Radioactive waste that deviates from the fuel cycle is planned to be safely sequestered. In particular, it is decided to dispose of high-level radioactive waste generated at reprocessing plants at the geological disposal facility, and at the geological disposal facility, in order to dispose of the final unusable radioactive waste, As shown in Fig. 3, it is constructed as an underground facility with a depth of 300m or below.

The geological disposal facility 10 includes an underground facility section 1 and a shaft 3 and an exhaust shaft 4 which connect the ground receiving facility 2 to the underground facility section 1.
It consists of The underground facility section 1 is composed of a plurality of disposal tunnels 5 and a main tunnel 6 that connects them, and the shaft 3 has a canister carry-in shaft 7, a personnel / material shaft 8, and an emergency shaft 9. .

[0004] The geological disposal facility is planned and designed by classifying into two types of facilities, one is hard rock and the other is soft rock such as sedimentary rock, depending on the type of rock. And the horizontal system is considered, and the technical examination about each facility is done.

The disposal tunnel 5 is still excavated by TBM, but in the case of soft rock, it is constructed by excavating it and supporting it by lining using a lining concrete or compressed concrete segment with a thickness of about 50 cm. ing.

The conventional vertical placement method is a method in which a disposal hole is excavated from the bottom of a disposal tunnel as shown in FIG. 4 (a), and the waste is placed vertically in the pit with a buffer material interposed. Yes, in the case of the vertical placement method for soft rock, it is constructed in a state of being reinforced by a lining as shown in the figure.

That is, the disposal tunnel 11 has a bottom portion 12 and a side portion 1.
3 are formed in an arc shape with different radii, and the upper part 14 is the side part 1.
A semicircular shape whose radius is drawn from the upper end of the arc of No. 3 is half the width of the disposal tunnel 11, and a lining 15 using a lining concrete or a compressed concrete segment with a thickness of about 50 cm is constructed on it. Therefore, the disposal tunnel 11 and the disposal hole 16 are arranged at a wider interval than in the case of hard rock.

To dispose of the waste body 17 in the disposal hole 16, the bottom of the disposal hole 16 is filled with the powder cushioning material, the waste body 17 is buried and then set, and then the disposal hole 16 and the disposal tunnel 1 are placed.
A cushioning material 18 made of bentonite or the like is enclosed in 1.

Since the disposal tunnel 5 is also filled with the same cushioning material 19, the size of the disposal tunnel is medium, but the influence of excavation of the disposal hole on the stability of the rock mass and the heat of the waste body. Considering the effect of the above, the burial density of waste cannot be secured so high.

On the other hand, the horizontal placement method is shown in FIG.
As shown in (4), the waste material 17 is placed laterally under the interposition of the buffer material 18 equivalent to that filled in the vertical disposal hole 16, and the waste material 17 is aligned in the axial direction of the disposal tunnel 20 excavated. In the case of a soft rock type rock, the disposal tunnel 21 is configured in an elliptical shape in the vertical direction as shown in the figure to strengthen the stress level.

Therefore, since all the disposal tunnels have a small diameter, excavation of the disposal hole does not affect the stability of the rock mass, but it is still necessary to consider the influence of groundwater and the elution of radioactive materials due to the corrosion of the waste container. Therefore, it is not possible to secure a large burial density of waste as in the vertical placement method.

[0012]

However, in any of the burial systems, in order to isolate high-level radioactive waste from the natural environment for a very long period of 10,000 years or more,
Even after being placed in the disposal tunnel as a waste, by suppressing the dangerous phenomenon of the waste part as follows,
It is necessary to establish safety while increasing the disposal density of waste. Do not flood groundwater into the waste part. Does not corrode the metal of the waste. Do not elute radioactive materials from corrosive metals in waste. Do not disperse the eluted radioactive material into the groundwater in the disposal tunnel or surrounding rock.

The present invention proposes an improvement measure in the disposal of high-level radioactive waste in view of the above required quality, and by solving the above problems, the disposal density of waste is increased. We provide disposal tunnels and filling buffers for geological disposal facilities that reduce the construction cost by reducing the size of the entire underground facility and relaxing the restrictions on suitable rock.

[0014]

DISCLOSURE OF THE INVENTION The disposal tunnel of a geological disposal facility according to the present invention is basically a disposal tunnel of a geological disposal facility in which a sealed body filled with a waste material is buried with a buffer material around the periphery. The intervening cushioning material is made of a low water-permeable material, and an oxidizing agent is mixed therein, and the oxidizing agent to be mixed is an iron material.

Thus, by reducing the flow velocity, a corrosive factor such as oxygen is eliminated and reduced before the groundwater having a small flow rate reaches the waste body, which causes problems due to groundwater flow and corrosion of the waste container. By solving the above, the constraints on the bedrock are relaxed.

Further, the filling cushioning material according to the present invention is basically a filling cushioning material to be interposed around the closure body in the disposal tunnel of the geological disposal facility in which the closure body filled with the waste is buried. The filling cushioning material is made of a low water-permeable material and is mixed with an oxidizer. Specifically, the filling cushioning material is formed in a block shape.

This facilitates the handling of the filling buffer material in the disposal tunnel of the geological disposal facility and improves the operability when placing the waste, thereby improving the workability of the disposal tunnel of the geological disposal facility. I am letting you.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The disposal tunnel of a geological disposal facility according to the present invention is basically an interposer in a disposal tunnel of a geological disposal facility in which a sealed body filled with waste material is buried with a cushioning material interposed around it. The buffer material is made of a low water-permeable material, and an oxidizing agent is mixed therein, and in particular, the oxidizing agent to be mixed is an iron material or the like.

Embodiments of the present invention will be described in detail below with reference to the drawings. However, in order to clarify the features of the invention, the same parts as those in the conventional art are denoted by the same reference numerals.

FIG. 1 is a sectional view showing a flow state of groundwater in an embodiment of a disposal gallery of a geological disposal facility according to the present invention.

In the present embodiment, the case where the waste is disposed in the disposal tunnel of the geological disposal facility is set to the vertical placement method is exemplified. However, the bottom 12 of the disposal tunnel 11 is exemplified.
The waste body 17 buried in the disposal hole 16 formed in 1 is backfilled with the cushioning material 21 around the periphery thereof.

Disposal tunnel 11 of the geological disposal facility according to the present invention
Then, since the cushioning material 21 is made of bentonite or the like having low water permeability, the distribution state of the groundwater flow is formed as shown in the figure.

That is, the groundwater flow in the ground around the disposal hole 16 flows at a flow velocity corresponding to that, but at the disposal hole 16 backfilled with the cushioning material 21, the flow velocity is greatly reduced.

FIG. 2 is an enlarged view of the portion A of FIG. 1, showing the details of the backfilling with the cushioning material.

Although not shown in particular, in this embodiment as well, the waste body 17 is sealed by the metal container as in the conventional example, and the cushioning material 21 filling the periphery thereof is backfilled.
Is formed so as to stack rectangular block bodies 22 as shown in FIGS. 2 (a) and 2 (b).

In the gap 24 generated when the block bodies 22 are piled up and the gap between the block bodies 22, the powder of the cushioning material 21 made of bentonite or the like having low water permeability is naturally formed in the gap 24 and the gap 24. It is deployed to fill voids and is configured to limit the velocity of groundwater.

Further, the block body 22 and the buffer material 21 formed in powder form are constituted by mixing an oxidant 23 such as iron powder, and the buffer material 21 is bentonite or the like to flow the groundwater. The ground water and the oxidizer 23 having a slow flow rate are sufficiently reacted with each other while the flow rate of the above is being attenuated, and a reducing zone is formed therein.

Therefore, the oxygen in the groundwater is reduced by reacting with the oxidizing agent 23 of the buffer material 21, and as a result, the groundwater flow reaching the metal container of the waste 17 is dissolved by the reduction of the metal container. The residual oxygen and the like are almost eliminated by consuming the oxygen and the like that are generated, and the amount of the factor that promotes the corrosion of the metal container is eliminated and reduced.

The oxidant to be mixed is intended to consume oxygen and the like in the groundwater, and any oxidant of a type that can achieve this purpose can be similarly employed. Further, among various oxidizers, iron materials can be inexpensively adopted regardless of their shapes, and are therefore exemplified in the present embodiment and are not limited to these.

In addition, since the cushioning material 21 constitutes a matrix of bentonite or the like and contains an oxidizing agent 23 such as iron powder therein, the bentonite expands due to the permeation of groundwater, and at the same time iron powder or the like is also contained therein. Volume expansion is increased due to corrosion.

As a result, the cushioning material 21 has particularly improved the sealing performance established by the expansion as compared with the conventional cushioning material, and exhibits beneficial characteristics in addition to elimination and reduction of corrosion factors. is doing.

As described above, in the disposal tunnel of the geological disposal facility according to the present invention, the buffer material interposed around the waste is made of a low water permeable material and mixed with the oxidizer, so that the metal container Factors that promote corrosion are eliminated and reduced, and by reducing the flow velocity to avoid corrosion of the waste container with a small amount of groundwater, the constraint conditions for suitable rock mass are alleviated.

Next, the filling cushioning material according to the present invention will be described. The embodiment of the filling cushioning material according to the present invention is characterized in that the filling cushioning material is made of a low water-permeable material, and an oxidizer is mixed in the filling cushioning material, and the filling cushioning material is formed in a block shape in addition to the powder.

As described above, the filling cushioning material is made of bentonite or the like, and iron powder is mixed therein as an oxidizing agent. Thus, by interposing the filling cushioning material around the waste body, the filling cushioning material accelerates the reaction between the groundwater and the material such as iron material or iron powder while reducing the flow velocity of the groundwater flow around the waste body. Then, the reduction zone will be formed inside.

Therefore, the oxygen in the groundwater reacts with the oxidizing agent of the filling buffer material and is reduced, and the groundwater flow reaching the waste metal container eliminates oxygen and the like that dissolve the metal container by reduction. This eliminates and reduces the amount of factors that promote corrosion of metal containers.

In particular, when the filling cushioning material is formed in a block shape as shown in FIG. 2 (b), it is possible to make the mixed state of bentonite and iron powder uniform.
At the same time facilitates handling for placement around the waste,
By reliably filling the gaps and voids of the cushioning material with the powder-filled cushioning material, the factors that promote the corrosion of the metal container are eliminated and reduced more reliably.

As described above, in the filling cushioning material according to the present invention, the filling cushioning material is made of a low water-permeable material and is mixed with the oxidizing agent, so that the filling cushioning material in the disposal tunnel can be easily handled and discarded. By improving the operability when placing the body, the workability in the disposal tunnel of the geological disposal facility is improved.

The present invention has been described in detail above based on the embodiments. However, the disposal tunnel and the filling cushioning material of the geological disposal facility according to the present invention are not limited to the above embodiments, and the present invention is not limited to the embodiments. It goes without saying that various modifications can be made without departing from the spirit of the invention.

[0039]

EFFECTS OF THE INVENTION In the disposal tunnel of the geological disposal facility according to the present invention, the buffer material interposed is made of a low water permeability material, and the oxidizer is mixed therein. The following effects are exhibited by eliminating and reducing the corrosion factor of the waste container before reaching the above condition and increasing the expansion rate of the cushioning material. By suppressing the elution of waste, the disposal density can be increased and the entire underground facility can be reduced. By improving the sealing performance of the cushioning material, it is possible to reduce the entire form of preventing the infiltration of groundwater into the waste. Construction costs can be reduced by relaxing constraints on suitable rock mass.

The filling cushioning material according to the present invention is located in the disposal tunnel of the geological disposal facility and is made of a low-permeability material and mixed with an oxidizing agent to form a block shape. By facilitating the handling of the filling cushioning material and improving the operability when the waste is placed, it has the effect of improving the workability in the disposal tunnel of the geological disposal facility.

[Brief description of drawings]

FIG. 1 Flow diagram of groundwater in a disposal tunnel of a geological disposal facility according to the present invention

FIG. 2 is a detailed view (a) showing a state of backfilling with a cushioning material in a disposal tunnel of a geological disposal facility according to the present invention and a form diagram of a filling cushioning material (b).

[Fig. 3] Perspective view of the geological disposal facility by the conventional method

FIG. 4 is a perspective sectional view showing a vertical placement method (a) and a horizontal placement method (b) of a disposal tunnel and a disposal hole by a conventional method.

[Explanation of symbols]

1 underground facility, 2 ground receiving facility, 3 vertical shaft,
4 exhaust shafts, 5 disposal tunnels, 6 main tunnels,
7 Canister carry-in shaft, 8 Material shaft, 9 Emergency shaft, 10 Geological disposal facility, 11, 20 Disposal tunnel, 12 Bottom part, 13 Side part, 14 Top part, 15
Lining, 16 disposal holes, 17 waste, 18, 1
9, 21 cushioning material, 22 block body, 23 oxidant,
24 gaps,

Claims (4)

[Claims] 1. A disposal tunnel of a geological disposal facility in which a sealed body filled with waste material is buried with a buffering material intervening around it, and the buffering material to be interposed is made of a low water permeability material and mixed with an oxidizing agent. Disposal tunnel of geological disposal facility characterized by: 2. The disposal tunnel of the geological disposal facility according to claim 1, wherein the oxidizing agent mixed in the buffer material is an iron material. 3. A packing cushioning material which is present in a disposal tunnel of a geological disposal facility in which a sealing body filled with waste material is buried, and which is interposed around the sealing body, the filling buffering material being made of a low water-permeable material. A filling cushioning material characterized by containing an oxidizing agent. 4. The filling cushioning material according to claim 3, wherein the filling cushioning material is formed in a block shape.