JP4253783B2 - Geological disposal facility and its construction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a geological disposal facility and a construction method thereof, and more particularly, to a geological disposal facility and a construction method thereof that can secure the stability of surrounding rocks even in sedimentary rocks and can safely dispose of waste.
[0002]
[Prior art]
In the nuclear fuel cycle centered on nuclear power plants, in order to recycle spent fuel, spent fuel is transferred directly or via a recycle fuel storage center to a reprocessing plant, where uranium and plutonium are recovered. However, the radioactive waste that falls outside this fuel cycle is planned to be safely isolated and disposed of. Of these, low-level radioactive waste discharged from nuclear power plants is safely buried in low-level radioactive waste burial centers.
[0003]
On the other hand, for high-level radioactive waste generated at reprocessing plants, it is decided to dispose of waste in the geological disposal facility after storing the waste for cooling in the high-level radioactive waste storage facility. In the disposal facility, in order to dispose of high-level radioactive waste, as shown in FIG. 7, it is constructed as an underground facility deeper than 300 m underground.
[0004]
The geological disposal facility 10 includes an underground facility section 1 and a vertical shaft 3 and an exhaust vertical shaft 4 that communicate with the ground receiving facility 2. The underground facility section 1 is composed of a plurality of disposal tunnels 5 and a main tunnel 6 connecting them, and the shaft 3 has a canister carry-in shaft 7, a personnel / material shaft 8, and an emergency shaft 9. .
[0005]
Geological disposal facilities are classified and designed according to the type of rock, which are hard rocks and sedimentary rocks, and technical studies on each facility are underway.
[0006]
The geological disposal facility in soft rock is constructed with sedimentary rock, which is lower in strength than granite, and the disposal tunnel 5 in the geological disposal facility for sedimentary rock is disposed with the disposal tunnel 19 and disposal as shown in FIG. It consists of holes 11.
[0007]
The disposal tunnel 19 is a tunnel for transporting the waste body 12 and burying it in the bottom plate portion 13 of the tunnel, and the disposal hole 11 is a hole for finally burying the waste body 12.
[0008]
The disposal tunnel 19 is constructed by excavating with a TBM and then supported by a concrete segment, and the disposal hole 11 is created by excavating from the disposal tunnel 19 after the disposal tunnel 19 is constructed.
[0009]
The disposal operation of the waste body 12 is performed by first filling the disposal hole 11 with the cushioning material 14 at the bottom made of bentonite or the like and then enclosing the cushioning material 15, and then burying the waste body 12 in the cushioning material 15. After that, the upper end of the cushioning material 15 is sealed with a lid-shaped cushioning material 16.
[0010]
When the waste body 12 is embedded, the powder body 17 is interposed between the upper and lower ends of the waste body 12 so that the fixing of the waste body 12 is stabilized.
[0011]
The disposal hole 11 further encloses a buffer material 18 made of bentonite or the like in the remaining space, and finally, the disposal operation of the waste body 12 is completed by filling the buffer material into the disposal tunnel 19. .
[0012]
Therefore, the conventional design plan is centered on the stable design of the disposal tunnel, and the support specifications necessary to stabilize the tunnel by carrying out a study on the stability around the tunnel are defined. On the other hand, the stability and safety of excavation of the disposal hole have not been studied, and it is also considered to place the waste without supporting without considering the necessity of support. .
[0013]
[Problems to be solved by the invention]
However, in the case of tunnels constructed in the same strata, when evaluating the stability, the result is that there is no difference in the stability of ground around the tunnel depending on the diameter of the tunnel.
[0014]
Therefore, when it is judged that support is necessary for the stability of the disposal tunnel, some support is also applied to the disposal hole in order to ensure the stability of the disposal hole so as not to cause a difference in stability in the surrounding ground. It is necessary to ensure stability.
[0015]
However, as in the conventional design / examination, only the establishment of stability for the disposal mine is considered with respect to the stability of the surrounding ground, and the situation that does not consider the disposal hole is the high-level radioactive in nuclear power generation. This is a safety concern in the disposal of waste.
[0016]
The present invention proposes an improvement measure in the geological disposal of high-level radioactive waste in view of the above-mentioned current situation, and the disposal hole is arranged so as not to cause a difference in stability in the surrounding natural ground with respect to the disposal hole. By providing support, we provide a geological disposal facility that secures its stability and eliminates safety concerns and its construction method.
[0017]
[Means for Solving the Problems]
The geological disposal facility according to the present invention basically forms a disposal hole in an excavated disposal tunnel, and in the geological disposal facility in which waste is buried and placed in a buffer material enclosed in the disposal hole, The bottomed steel pipe is filled with the buffer material to be enclosed, and specifically, the bottom of the bottomed steel pipe is formed into a flat surface or a spherical surface, and it is constructed in a formation made of sedimentary rock. Yes.
[0018]
This ensures the stability of the bedrock around the disposal hole in the geological disposal facility where the waste is buried even in geological formations consisting of hard rock and sedimentary layers, and to dispose of high-level radioactive waste from nuclear power generation Has established safety.
[0019]
In addition, according to the construction method of the geological disposal facility according to the present invention, a disposal hole is formed in the excavated disposal tunnel, a bottomed steel pipe is installed in the disposal hole, a buffer material is enclosed, and then the sealed buffer material is enclosed. The waste body is buried and placed, and then the waste body is sealed with a lid-like buffer material, and then the disposal hole is filled with the buffer material. In addition, the disposal hole in the geological disposal facility where waste is buried is rationally constructed to ensure the stability of the surrounding ground.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The geological disposal facility according to the present invention has a buffer material enclosed in the disposal hole in order to form a disposal hole in the excavated disposal tunnel and to embed and place the waste in the buffer material sealed in the disposal hole. It is arranged by filling the bottom steel pipe, and is characterized by being constructed in a stratum composed of hard rock, especially sedimentary rock.
[0021]
Embodiments of the present invention will be described below in detail with reference to the drawings. In order to clarify the features of the present invention, the same parts as those in the prior art are denoted by the same reference numerals.
[0022]
FIG. 1 is a cross-sectional view showing an embodiment of a disposal mine and a disposal hole in a geological disposal facility according to the present invention.
[0023]
The waste body 12 made of high-level radioactive waste generated by nuclear power generation buried in a geological disposal facility is a glass solidified body formed by mixing the waste liquid of high-level radioactive waste with glass to prevent scattering. It is formed in a state where it is stored in a metal container such as a 20 cm overpack, and prevents high-level radioactive waste from coming into contact with groundwater.
[0024]
In order to ensure the safety of the tunnel from the disposal of the waste to the backfilling of the disposal tunnel, the disposal tunnel 19 and the disposal hole 11 are built, but the disposal tunnel 19 has been excavated with TBM. The disposal hole 11 that is constructed by supporting the concrete segment and finally embeds the waste body 12 is constructed by excavating from the bottom plate 13 of the disposal tunnel 19 after the disposal tunnel 19 is constructed.
[0025]
In addition, arrangement | positioning of the disposal hole 11 is not limited to the bottom board part 13 of the disposal tunnel 19, The disposal hole 11 may be formed in the side part of the disposal tunnel 19, and the waste body 12 may be installed horizontally. However, the disposal hole 11 in this case is excavated from the side of the disposal tunnel 19.
[0026]
A vertical bottomed steel pipe 20 is inserted into the disposal hole 11 in order to secure the stability of the surrounding rock mass including the peripheral wall and the bottom, but the bottomed steel pipe 20 is placed vertically as described above. Therefore, the shape is formed in a shape corresponding to the position of the disposal hole 11 with respect to the disposal tunnel 19 and the excavation hole for the disposal hole 11.
[0027]
The bottom portion of the bottomed steel pipe 20 is packed with a bottom cushioning material 14 made of bentonite or the like, and the cushioning material 15 is disposed thereon.
[0028]
The waste body 12 is fixed in the buffer material 15, and the adhesiveness between the waste body 12 and the buffer material 15 is increased by interposing powder or granular buffer materials 17, 17 at the upper and lower ends thereof. On the other hand, the upper end of the waste body 12 is sealed with the lid-like cushioning material 16 so that the fixing of the waste body 12 is stabilized.
[0029]
In the disposal hole 11, a buffer material 18 made of bentonite or the like is further sealed in the remaining space, and finally the buffer material is filled up to the disposal tunnel 19.
[0030]
Therefore, the cost of placing a bottomed steel pipe in the disposal hole is described. For example, the ratio of the diameter of the disposal hole and the disposal tunnel that are similar to each other is about 1/5. If the material of the same strength material is used, the ratio of the strength borne by will be proportional to (1/5) ² , and the thickness of the material used to secure the rigidity necessary for the disposal hole is It becomes extremely thin compared to that of the disposal tunnel.
[0031]
In particular, when the bottomed steel pipe 20 is composed of a steel material that exhibits high strength for supporting the disposal tunnel, the thickness of the steel pipe is the minimum thickness determined from the workability and functionality at the time of embedment, You will be able to cope with it. Therefore, even if a bottomed steel pipe is disposed in the disposal hole, the bulkiness in terms of cost is kept to such an extent that it hardly causes a problem.
[0032]
As described above, the geological disposal facility according to the present invention is arranged by filling the bottomed steel pipe with the buffer material enclosed in the disposal hole, so that the stability of the rock around the disposal hole is surely secured, and the disposal facility In addition to rationalizing the design and construction of the product, it prevents the buffer material from coming into contact with water, eliminates the swelling of the buffer material, etc. There is also an effect of reducing the corrosion rate of the stored metal container.
[0033]
FIG. 2 is a perspective view showing an embodiment of a bottomed steel pipe inserted into the disposal hole.
FIG. 2 (a) is an embodiment in which the bottom of a bottomed steel pipe is formed into a flat surface. In this embodiment, the bottom of the bottomed steel pipe can be handled as a disposal hole that is excavated in a cylindrical shape and forms a flat bottom as in the prior art. It is configured as follows.
[0034]
The bottomed steel pipe 21 is composed of a cylindrical portion 22 that is in close contact with the peripheral wall of the disposal hole and ensures the stability of the rock around the disposal hole, and a flat bottom plate 23 that ensures the stability of the rock in the lower portion of the disposal hole. In addition, the cylindrical portion 22 and the bottom plate 23 are closely joined so that the groundwater does not penetrate into the metal container storing the cushioning material or waste body filled therein.
[0035]
Therefore, the bottomed steel pipe 21 ensures the stability when placed vertically in the disposal hole, and the stability of the surrounding rock mass is ensured, and at the same time the verticality of the waste body is secured and the fixing property is improved. ing.
[0036]
FIG. 2 (b) is an embodiment in which the bottom of a bottomed steel pipe is formed into a spherical surface. In this embodiment, the spherical surface has a function to improve the safety of the hole bottom and disposal to be excavated. It has a function that can flexibly cope with the bottom of the hole that is not maintained flat.
[0037]
The bottomed steel pipe 25 is in close contact with the peripheral wall of the disposal hole as in the above-described embodiment, and the spherical surface 22 that secures the stability of the cylindrical portion 22 for securing the stability of the rock around the disposal hole and the rock in the lower portion of the disposal hole. The cylindrical portion 22 and the bottom plate 26 are joined together in a dense state so that the groundwater does not penetrate into the metal container storing the cushioning material and waste body filled therein. Yes.
[0038]
Therefore, the bottomed steel pipe 25 ensures the stability when it is placed even when the bottom of the disposal hole is not evenly maintained, and at the same time the stability of the surrounding rock is improved. The fixability is improved by ensuring the verticality.
[0039]
Next, the construction method of the geological disposal facility according to the present invention will be described.
According to the construction method of the geological disposal facility according to the present invention, a disposal hole is formed in an excavated disposal tunnel, a bottomed steel pipe is installed in the disposal hole, a buffer material is enclosed, and then a waste body is placed in the enclosed buffer material. It is buried and placed, and then the waste body is sealed with a lid-like buffer material, and then the disposal hole is filled with the buffer material, so that only by installing a thin bottomed steel pipe that can ensure economic efficiency, In the formation of hard rocks and sedimentary layers, disposal holes for placing waste bodies are rationally constructed to ensure the stability of the surrounding ground.
[0040]
Hereinafter, embodiments of each invention will be described in detail with reference to the drawings. The same parts as those in the above drawings are denoted by the same reference numerals.
[0041]
3-6 is sectional drawing of the disposal hole in each process in embodiment of the construction method of the geological disposal facility by this invention.
[0042]
FIG. 3 is a construction diagram of the bottom surface of the disposal hole.
As shown in FIG. 3A, the disposal hole 11 is excavated from the bottom plate portion of the disposal tunnel by a drilling machine 27, and the bottom portion is configured in a flat plate shape in this embodiment. As shown in FIG. 3 (b), the bottomed steel pipe 20 is laid in the disposal hole 11 after excavation to ensure the stability of the rock in the vicinity of the disposal hole and the bottom bottom, and against the buffer material and the like. Prevents penetration of groundwater.
[0043]
The process of FIG. 4 shows the stationary state of the cushioning material 15.
As shown in FIG. 4A, the cushioning material 15 is placed on the stationary device 28 while being held by the suspending device 29, and is transferred to the predetermined disposal hole 11 in that state.
[0044]
Next, as shown in FIG. 4B, the cushioning material 15 is inserted into the disposal hole 11 by the lowering of the suspension device 29 of the stationary device 28. At this time, the inner bottom of the bottomed steel pipe 20 is preliminarily filled with the bottom cushioning material 14 in the form of powder or granules, so that the stable fixing of the cushioning material 15 to the bottomed steel pipe 20 is established. Yes.
[0045]
FIG. 4C shows a process state in which the stationary device 28 accommodates and retracts the suspension device 29 after the buffer material 15 is fixed to the inner bottom of the bottomed steel pipe 20 with high accuracy.
[0046]
The process of FIG. 5 shows the embedded state of the waste body 12.
As shown in FIG. 5A, the waste body 12 is placed in a state where it is held by a different suspension device 29 ′ on the stationary device 28, and is transferred to a predetermined disposal hole 11 in that state. Come on.
[0047]
Next, as shown in FIG. 5B, the waste body 12 is inserted into the cushioning material 15 by the lowering of the suspension device 29 ′ of the stationary device 28. At this time, the inner bottom of the cushioning material 15 is previously filled with a cushioning material 17 at the bottom, such as powdered or granular, and the stable fixing of the waste body 12 to the cushioning material 15 is established.
[0048]
FIG. 5C shows a process state in which the stationary device 28 accommodates and retracts the suspension device 29 ′ after the waste body 12 cushioning material 15 is fixed to the inner bottom of the cushioning material 15 with high accuracy.
[0049]
The process of FIG. 6 shows a stationary state of the lid-like cushioning material 16.
As shown in FIG. 6A, the lid-like cushioning material 16 is placed on the stationary device 28 in a state where it is not held by the suspension device 29, and is transferred to a predetermined disposal hole 11 in that state. The
[0050]
Next, as shown in FIG. 6 (b), the lid-like cushioning material 16 is inserted onto the cushioning material 15 of the bottomed steel pipe 20 by being suspended and lowered by the suspension device 29 of the stationary device 28. . At this time, the upper end surface of the waste body 12 is preliminarily filled with a buffer material 17 such as powder or granule, and is discarded by the powder or granule buffer material 17 filled at the upper and lower ends of the waste body 12. A stable fixing of the body 12 to the cushioning material 15 is established.
[0051]
FIG. 6C shows a process state in which the stationary device 28 accommodates and retracts the suspension device 29 after the lid-shaped buffer material 16 is accurately fixed on the buffer material 15 of the bottomed steel pipe 20. The state where the disposal work of the waste body 12 is completed is displayed.
[0052]
As is clear from the above work process, the construction method of the geological disposal facility according to the present invention is only to install an inexpensive thin bottomed steel pipe that is economical enough to secure the hard rock and the sedimentary layer. The disposal hole for placing waste is set up rationally to ensure the stability of the surrounding ground and the solid establishment of the waste.
[0053]
As described above, the present invention has been described in detail based on the embodiment. However, the geological disposal facility and the construction method according to the present invention are not limited to the above embodiment, and the shape of the waste body and the disposal hole are not limited. Of course, various changes can be made to the arrangement and construction apparatus of the present invention without departing from the spirit of the present invention.
[0054]
【The invention's effect】
The geological disposal facility according to claim 1 is formed in a disposal hole in order to form a disposal hole in an excavated disposal tunnel and embed and place the waste in a buffer material enclosed in the disposal hole. Since the bottomed steel pipe is filled with the cushioning material to be placed, the stability of the rock mass around the disposal hole is ensured, the design and construction of the disposal facility is rationalized, and the following effects I play.
(1) Since the bottom of the steel pipe is provided to prevent the buffer material for burying the waste material from coming into contact with water, the quality of the waste material disposal can be ensured without swelling of the buffer material.
{Circle around (2)} Corrosion of steel pipes can reduce the corrosion rate of metal containers such as overpacks that store waste in a reducing atmosphere around the surrounding ground.
[0055]
The geological disposal facility according to claim 2 is characterized in that, in the geological disposal facility according to claim 1, the bottom of the bottomed steel pipe is formed into a flat surface. It has the effect of ensuring stability when the steel pipe is placed vertically.
[0056]
The geological disposal facility according to claim 3 is characterized in that, in the geological disposal facility according to claim 1, the bottom portion of the bottomed steel pipe is formed into a spherical surface. It has the effect of ensuring the stability when the bottomed steel pipe is placed vertically by easily corresponding to the bottom surface of the excavated.
[0057]
The geological disposal facility according to claim 4 is characterized in that in the geological disposal facility according to any one of claims 1 to 3, the geological layer is sedimentary rock, so the geological layer has lower strength than granite. Even if there is a problem, the disposal facility can be constructed.
[0058]
According to the construction method of the geological disposal facility according to the present invention, a disposal hole is formed in an excavated disposal tunnel, a bottomed steel pipe is installed in the disposal hole, a buffer material is enclosed, and then a waste body is placed in the enclosed buffer material. Since the waste is sealed with lid-shaped cushioning material and the disposal holes are filled with cushioning material, the hard rock is simply installed by installing a thin bottomed steel pipe that can ensure economic efficiency. In addition, it has the effect of ensuring the stability of the surrounding ground by rationally constructing a disposal hole for placing waste in landfills and sedimentary layers.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a disposal tunnel and a disposal hole in a geological disposal facility according to the present invention. FIG. 2 is a perspective view showing an embodiment of a bottomed steel pipe used in the geological disposal facility according to the present invention. Construction diagram of bottom surface of disposal hole in construction method of disposal facility [Figure 4] Construction diagram showing the stationary state of buffer material in construction method of geological disposal facility of the present invention [Figure 5] Disposal in construction method of geological disposal facility of the present invention Construction diagram showing the buried state of the body [Fig. 6] Construction diagram showing the state of placing the lid-like cushioning material in the construction method of the geological disposal facility of the present invention [Fig. 7] Perspective view of the geological disposal facility by the conventional construction method [Fig. 8] Cross-sectional view of disposal tunnel and disposal hole by conventional method 【Explanation of symbols】
1 underground facilities, 2 ground receiving facilities, 3 shafts, 4 exhaust shafts,
5 disposal tunnels, 6 main tunnels, 7 canister carry-in shafts,
8 Material shafts, 9 Emergency shafts, 10 Geological disposal facilities,
11 disposal hole, 12 waste body, 13 bottom board,
14, 17, 18 cushioning material, 15 cushioning material, 16 lid-shaped cushioning material,
19 disposal tunnels, 20 bottomed steel pipes, 21, 25 bottomed steel pipes,
22 cylindrical portion, 23 flat bottom plate, 26 spherical bottom plate,
27 drilling machine, 28 stationary device, 29, 29 'hanging device,

Claims (5)

It is a geological disposal facility where a disposal hole is formed in the excavated disposal tunnel, and the waste is buried in the buffer material enclosed in the disposal hole, and the bottomed steel pipe is filled with the buffer material enclosed in the disposal hole A geological disposal facility characterized by being arranged. The geological disposal facility according to claim 1, wherein the bottomed steel pipe has a flat bottom. The geological disposal facility according to claim 1, wherein the bottomed steel pipe has a spherical bottom. The geological disposal facility according to any one of claims 1 to 3, wherein the geological layer is composed of sedimentary rock. Form a disposal hole in the excavated disposal tunnel, install a bottomed steel pipe in the disposal hole, enclose the buffer material, then embed the waste body in the enclosed buffer material and place it in place, and then cover it The construction method of the geological disposal facility according to any one of claims 1 to 4, wherein the disposal body is sealed with a buffer material and then the disposal hole is filled with the buffer material.

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