JPH05203797A - Radioactive waste disposal site - Google Patents

Abstract

PURPOSE:To obtain a radioactive waste disposal site which enables suppression of groundwater flow in geological formations adjacent to the site and thereby enables prevention of radioactive contamination by the grandwater flow, in burial disposal case of radioactive wastes into a geological formation under a coastal sea bed. CONSTITUTION:Into a geological formation between storage tunnels 9 for radioactive wastes which are formed in a geological formation under a coastal sea bed, and a sea side zone 3, a plurality of boring holes 10a are drilled and formed vertically in a manner that the holes cross through saline groundwater flow under natural condition, and then sea water introducing pipes 11 are connected to an upper side wall of each of the boring holes 10a. By supplying enough sea water which is introduced to the boring holes 10a, to a flow path of the saline ground water flow under natural flowing condition from the boring holes 10a, flow of the saline ground water flow can be suppressed to the extent to be almost ignored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a radioactive waste disposal site, and more specifically, by using a groundwater flow control method, it is possible to safely reach below the coastal seabed, which was not a disposal area in the past. The present invention relates to a new radioactive waste disposal site capable of disposing of radioactive waste.

[0002]

2. Description of the Related Art Conventionally, there are two types of disposal sites for low-level radioactive waste from nuclear power plants, namely, a disposal site where an isolated place is provided on land and a deep sea floor.

[0003]

[Problems to be Solved by the Invention] The national land of Japan is surrounded by sea on all sides and tends to be mountainous, and the land use rate of the remaining flat land is extremely high. Due to the large amount of precipitation, radioactive waste buried underground by groundwater There is a disadvantageous condition to dispose of radioactive waste on land, such as the possibility that radioactive contamination spreads from things. Moreover, considering that the amount of radioactive waste to be disposed of will increase in the future, it is naturally expected that the seabed will be the disposal site for such radioactive waste in the country.
However, the dumping to the deep sea bottom has problems that the disposal place is limited, the transportation distance of the waste is long, the transportation cost and the risk of accident during transportation are high.

Therefore, compared to the deep sea floor, there are more disposal sites,
Due to the short transportation distance of waste, it may be buried in the ground beneath the coastal seabed where transportation costs are low and the risk of accidents during transportation is low. Since the groundwater of seawater, which is salt water, and the groundwater of saltwater exist on the land side and the sea side, respectively, a density flow due to the difference in salinity occurs in groundwater. When radioactive waste is disposed under the coastal seabed due to the groundwater flow due to this density current, the radioactively contaminated groundwater near the disposal site expands the contaminated area, affecting the surrounding ecosystem and local residents. There is a risk of it.

In view of the above circumstances, the present invention provides a radioactive waste disposal site capable of preventing radioactive contamination due to groundwater flow even when radioactive waste is buried in the stratum below the coastal seabed. It is an object.

According to the present invention, a storage space (9) for radioactive waste (16) is formed in the ground below the coastal seabed (2a), and the storage space (9) and the coastal area (3) are formed. Between the two), the hole (10
a), a plurality of a) are formed so as to intersect with the saline groundwater flow (2d), and the shape retaining material (10) is formed in each of the holes (10a).
b, 10c), and seawater introducing means (11) is provided above the respective holes (10a). Note that ()
The numbers in the drawings indicate the corresponding elements in the drawings for convenience, and the present description is not limited to the description in the drawings. below

The same applies to the column of [Operation].

[0006]

With the above-mentioned structure, the present invention has the advantages that each hole (1
The seawater (2b) introduced into 0a) acts so as to leak from the side wall and bottom of the hole (10a) into the ground between the storage space (9) and the waterfront (3).

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a radioactive waste disposal site of the present invention. FIG. 2 is a front view showing the radioactive waste disposal site of the present invention. FIG. 3 is a cross-sectional view taken along the line III-III of the boring hole row in FIG. 2, showing a case where the boring holes are arranged at intervals. Figure 4
FIG. 3 is a cross-sectional view of the row of boring holes taken along a line along line III-III, showing a case where the boring holes are arranged adjacent to each other. FIG. 5 is a view from above of the storage tunnel of FIG. FIG. 6 is a cross-sectional view of FIG. 5 taken along the line VI-VI. FIG. 7: is a figure showing the groundwater flow in the ground of the coast of a natural state.

As shown in FIG. 1, the radioactive waste disposal site 40 in the coastal area 1 according to the present invention has a storage facility entrance 14 in a coastal area 3 which is a land part of the coastal area 1, A plurality of vertical shafts 12a are formed in the inlet 14 in the vertical direction. The vertical shaft 12a is provided with a transportation means such as an elevator 14a, and the vertical shaft 12a is connected to the horizontal shaft 12b at the ground 3a of the seaside land 3. Horizontal shaft 12b
Is formed in the stratum below the coastal seabed 2a, and the working tunnel 13 is
a and 13a are formed in a horizontal plane so as to form a cross shape with the horizontal shaft 12b, and the working tunnels 13b and 13b are also formed in the horizontal plane together with the horizontal shaft 12b on both side walls at the end of the horizontal shaft 12b. It is formed so as to form a letter shape. At the end of each of the working tunnels 13a and 13b, a working tunnel 13c formed in parallel with the horizontal shaft 12b is connected so as to connect both tunnels 13a and 13b, and the working tunnel 13a is connected. A plurality of storage tunnels 9 are formed in a direction parallel to the work tunnels 13a and 13b from both side walls of the horizontal shaft 12b from the position to the end, and are connected to the work tunnel 13c. As shown in FIGS. 5 and 6, pits 9b, which are cylindrical holes, are provided on the bottom surface 9a of the storage tunnel 9, and many pits 9b are arranged at equal intervals in the depth direction of the storage tunnel 9. Has been done.

The radioactive waste disposal site 40 of the present invention is provided in the coastal area 1 as described above, but in the ground 1a of the coastal area 1 in a natural state, as shown in FIG.
There is a saltwater groundwater flow 2d on the side, and a freshwater groundwater flow 3b on the seaside 3 side. The saltwater groundwater flow 2d and the freshwater groundwater flow 3b flow in the directions approaching each other, and contact the ground near the boundary between the coastal sea area 2 and the seaside area 3, and the fresh salt boundary surface 21
Is formed. The storage tunnel 9 and the waterfront 3 are formed so as to intersect with the saltwater groundwater flow 2d in the natural state shown in FIG.
As shown in FIGS. 1 and 2, a boring hole row 10 is provided in the ground between the boring hole rows 10.
Are formed by a plurality of boring holes 10a that are vertically excavated to form a cylindrical shape. Each boring hole 1
0a are arranged in a line with a constant space L1 between adjacent boring holes 10a. Each boring hole 1
The inner wall of 0a remains uncut in the hard rock layer 6 deep in the ground, and in the earth and sand layer 7 formed of soft earth and sand near the surface of the earth, the steel pipe 1 having a plurality of holes on the side surface 1
0b is inserted. As shown in FIG. 3, the boring hole 10a is filled with crushed stones 10c, and the opening on the ground surface of the boring hole 10a is closed by a lid 10d.
An inlet 11a of a seawater introducing pipe 11 is connected to the upper side wall of the boring hole 10a, and the seawater introducing pipe 11 passes through the stratum below the coastal seabed 2a and into the sea in the coastal sea area 2.
protruding b. The inlet 11b is the inlet 11
It is located higher than a.

Since the radioactive waste disposal site 40 has the above structure, the radioactive waste 16 is stored in the storage facility entrance 14
Through the vertical shaft 12a and horizontal shaft 12b, below the coastal seabed 2
It can be carried into the storage tunnel 9 provided in the ground of a. In addition, transportation in the vertical shaft 12a is performed by the elevator 1
The radioactive waste 16 carried into the storage tunnel 9 by a transporting means such as 4a can be stored in the storage tunnel 9 in an orderly manner by burying it in the pit 9b. The work tunnels 13a, 13b, 13c facilitate the transfer of people and goods from any storage tunnel 9 to another storage tunnel 9. In addition, from the inlet 11b of each seawater introduction pipe 11 protruding into the sea of the coastal sea area 2, the seawater 2
b flows into each boring hole 10a from the inlet 11a through the seawater introducing pipe 11,
Seawater 2b is constantly filled in a while maintaining the tide level LV of the coastal sea area 2. The boring hole 10a
Is the steel pipe 10b and the crushed stone 10 even if seawater 2b is injected.
The shape is retained by c. The seawater 2b injected into the boring hole 10a leaks from the side wall and bottom of the boring hole 10a into the ground between the storage tunnel 9 and the waterfront 3,
The leaked seawater 2b tries to flow to the land side where the freshwater groundwater flow 3b exists due to the difference in salinity. On the other hand, the groundwater 2c on the right side of the borehole row 10 in FIG. 2, that is, between the storage tunnel 9 and the borehole row 10 also tends to flow to the land side due to the difference in salt concentration, like the seawater 2b. Since the saltwater groundwater 2c flows into the ground below the coastal seabed 2a, it is much more difficult to supply saltwater than the seawater 2b introduced directly into the boring hole array 10 from the sea. Therefore, the flow of salt water caused by the difference in salt concentration is sufficiently supplied to the land side by the sea water from the boring hole 10a, and the flow of the ground water 2c of salt water becomes negligibly small. Therefore, even if the saltwater groundwater 2c near the storage tunnel 9 is radioactively contaminated, the flow of the saltwater groundwater 2c is so small that it cannot be ignored, and the contaminated area does not expand. In addition, the seawater 2b leaked from the boring hole row 10 flows to the land side, and at the same time, the freshwater groundwater flow 3b flows to the sea side from the ground on the land side, and the freshwater groundwater stream 3b and the leaked seawater 2b are In the figure, the new fresh salt boundary surface 20 is formed in contact with the left side, that is, the land side. The new fresh-salt boundary surface 20 is formed in a straight line rising to the right in the figure such that the freshwater groundwater stream 3b rides on the leaked seawater 2b flow, and the seawater 2b and the freshwater groundwater stream 3b are the new fresh-salt boundary surface. Flows diagonally upward in the figure along 20 and flows out to the ground or the sea floor. By the way, in the above-mentioned embodiment, the boring hole row 10 is composed of the adjacent boring holes 1.
0a is arranged in a line at a constant interval. However, as shown in FIG. 4, adjacent boring holes 10a are arranged side by side in a row, or plural rows are arranged instead of one row. Also in this case, the same effect as that of the above-described embodiment can be obtained. The location of the row of boring holes 10 does not necessarily have to be the ground 3a of the waterfront 3 as long as it is in the ground between the storage tunnel 9 and the waterfront 3, and may be in the ground 2a below the coastal seabed. In this case, since the seawater naturally flows into the boring hole 10a by keeping the upper surface of the boring hole 10a open, the seawater introducing pipe 11 is not necessary. Even if the shape retaining means of the boring hole 10a is used, it is not always necessary to fill the crushed stone 10c, and the shape retaining means such as inserting a steel pipe having a large number of holes on the side surface over the entire bore hole 10a. May be taken. Further, the storage tunnel 9 does not necessarily have to be a tunnel as long as the space required for storage can be secured. The storage facility entrance 14 does not necessarily have to be at the waterfront 3, but may be at a floating island on the coast. The tunnel that connects the storage facility entrance 14 and the storage space does not necessarily have to be a combination of the vertical shaft 12a and the horizontal shaft 12b in the above embodiment, and only the inclined shaft and the vertical shaft are taken into consideration in consideration of the surrounding topography.
Of course, either a combination of a vertical shaft and an inclined shaft or a combination of an inclined shaft and a horizontal shaft may be constructed. The radioactive waste 16 is glass-solidified and is made of stainless steel container 1
7, the stainless steel container 19 was further enclosed in the cast iron container 19 and was carried in from the storage facility entrance 14, and as shown in FIG. Predetermined pit 9 filled with a certain crack 18 (or bentonite)
After burying radioactive waste 16 in all b, storage tunnel 15, working tunnels 13a, 13b, 13c, shaft 1
2a and the horizontal shaft 12b are also filled with the generated crack 18 (or bentonite).

[0011]

As described above, according to the present invention,
A storage space such as a storage tunnel 9 for storing radioactive waste 16 is formed in the ground below the coastal seabed 2a, and in the ground between the storage space and the seaside 3, a boring hole 10a having vertical seawater flowability. A plurality of holes, etc., are formed so as to intersect with the saltwater groundwater flow 2d, shape-retaining materials such as steel pipes 10b, crushed stones 10c, etc. are provided in each of the holes, and a seawater introducing pipe 11 is provided above each hole. Since it was configured by providing seawater introduction means such as
Even when radioactive waste is buried in the stratum below the coastal seabed, seawater can be supplied from the hole 10a to the seaside 3 side in the form of newly forming a fresh salt boundary surface. The flow of saline groundwater in the ground can be suppressed to a level that can be almost ignored, and radioactive contamination due to groundwater flow can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a perspective view showing a radioactive waste disposal site of the present invention.

FIG. 2 is a front view showing a radioactive waste disposal site of the present invention.

FIG. 3 is a cross-sectional view of the row of boring holes taken along the line III-III in FIG. 2, showing a case where the boring holes are arranged at intervals.

FIG. 4 is a cross-sectional view taken along the line III-III of the boring hole row in FIG. 2, showing a case where the boring holes are arranged adjacent to each other.

5 is a top view of the storage tunnel of FIG. 1. FIG.

FIG. 6 is a cross-sectional view taken along the line VI-VI of FIG.

FIG. 7 is a diagram showing groundwater flow in a coastal ground in a natural state.

[Explanation of symbols]

 2a ... Under the coastal seabed 2d ... Saltwater groundwater flow 3 ... Seaside 9 ... Storage space (storage tunnel) 10a ... Hole (boring hole) 10b ... Shape retaining material (steel pipe) 10c ... Shape retaining material ( Crushed stone) 11 …… Seawater introduction means (seawater introduction pipe) 16 …… Radioactive waste

Claims (1)

[Claims] 1. A storage space for radioactive waste is formed in the ground below the coastal seabed, and a plurality of holes having seawater flowability in the vertical direction are formed in the ground between the storage space and the seaside area. A radioactive waste disposal site constructed by piercing and forming a shape-retaining material in each of the holes, and seawater introducing means above each of the holes.