JPS61201200A - Equipment for treating stratum of radiation waste and execution method thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to a geological disposal facility for radioactive waste that buries radioactive waste in underground rock and isolates it from the biosphere above ground, and a method for constructing the same. It is.

"Conventional technology" High-level radioactive waste generated in the process of reprocessing spent nuclear fuel has high radiation activity over a long period of time, so it is necessary to take sufficient safety measures such as vitrification and store it for a certain period of time. After that, they must ultimately be separated from the biosphere by disposal.

Conventionally, a geological disposal facility as shown in FIG. 12, for example, has been considered as a facility for disposing of such radioactive waste. This facility has a tunnel 21 installed in bedrock G 500m to 1000m underground, a disposal pit 22 drilled on the floor of this tunnel 21, and a solidified package 23 of radioactive waste stored in this disposal pit 22. It was designed to do so. This solidified package 23 is made by sealing vitrified radioactive waste inside a stainless steel canister, but since it is stored semi-permanently, it is necessary to keep the canister as healthy as possible. There is. Therefore, in the case of this facility, a buffer material (clay with high water-stopping properties such as bentonite) is pre-compression molded in a factory into a semi-cylindrical shape as shown in Fig. 13 between the inner surface of the disposal pit 22 and the solidified material package 23. A plurality of water stop blocks 24 are provided in a stacked state to prevent water such as ground water from penetrating into the solidified package 23.

[Problems to be solved by the invention] However, in the geological disposal facility shown in Figure 12,
There are gaps in the many seams 25 between each water stop block 24. In other words, if moisture permeates through these seams 25 and touches the solidified package 23, the canister, which is heated to a high temperature due to the decay heat of the radioactive waste, will corrode in a short period of time, causing the radioactive nuclides inside to leak. Can you think of an accident that would happen?

The present invention was made in view of the above circumstances, and its purpose is to provide a highly sound radioactive waste disposal facility and its construction method by increasing the liquid tightness in the disposal pit. It is in.

"Means for Solving the Problems" The geological disposal facility for radioactive waste of the present invention includes a water-stop container formed by forming a buffer material into a container shape in the disposal pin,
A solidified package is housed in this water-stop container. In addition, the method for constructing a geological disposal facility of the present invention involves filling the disposal pit with buffer material and solidifying it, then drilling a storage hole in the buffer material, and inserting the solidified material package into the storage hole. In this method, the storage hole is then closed with a buffer material.

"Function" The geological disposal facility of the present invention reduces joints and suppresses the occurrence of gaps by integrally molding the buffer material into a container shape. Furthermore, the construction method of the present invention utilizes a disposal pit and forms the buffer material on-site, so that the buffer material is integrally adhered to the inner surface of the disposal pit and built into a strong state.

``Example'' An example of the present invention will be described below with reference to FIGS. 1 to 11.

FIG. 1 is a diagram showing the overall schematic configuration of the geological disposal facility of this embodiment, in which a mine shaft 1 is provided in the underground bedrock G in an almost mesh shape, and radioactive waste is deposited on the ground above the shaft I. There are 2 surface receiving facilities for the receiving, and these tunnels 1
A plurality of vertical shafts 3 are provided between the ground receiving facility 2 and the ground receiving facility 2 to connect the two.

The tunnels 1 are arranged in parallel at intervals in the horizontal direction, and
(A large number of disposal tunnels 4 excavated almost horizontally, and a main tunnel that divides these disposal tunnels 4 into several blocks 5 and connects all the disposal tunnels 4 while surrounding each block 5. 6. As shown in FIG. 2, on the inner surface of each disposal tunnel 4, for example, the floor surface, a large number of disposal pits 7 are provided at intervals in the longitudinal direction.

Each of these disposal pits 7 is a deep hole dug so as to have a circular cross section, and inside thereof, as shown in Fig. 3, a buffer material is integrally molded into a cylindrical shape with the top and bottom closed. A water stop container 8 is provided. This water-stop container 8 includes a container body 10 having an opening 9 at the upper end;
The lid body 11 is fitted into the opening 9 of the container body 10, and the opening 9 has a shape that gradually narrows the inner ocean downward from its upper end. The outer diameter gradually increases from the lower end to the upper end, that is, it has an inverted truncated conical shape. A cylindrical solidified package 12 in which radioactive waste is sealed in a canister is housed within this water-stop container 8 .

Next, to explain the construction method of such a geological disposal facility, a disposal pit 7 is excavated at the bottom of the tunnel 1 (disposal tunnel 4) as shown in Fig. 4, and powder is poured into this disposal pit 7 as shown in Fig. 5. While rolling out the body-shaped buffer material B in a certain amount (for example, a rolling thickness of 200 mm), this is
The materials are tamped and solidified one after another as shown in the figure, and the inside of the disposal pit 7 is filled with buffer material B as shown in FIG. Next, in this solidified buffer material B, as shown in FIG.
3 is bored, and an opening 9 is cut at the upper end of the storage hole 13 as shown in FIG. 9 to form a container body 10. After inserting the solidified package 12 into the storage hole 3 as shown in FIG. 10, the opening 9 of the storage hole 13 is closed with the lid 11 as shown in FIG. The package 12 is stored in the water-stop container 8.

In the geological disposal facility for radioactive waste configured in this way, the buffer material is integrally molded into the container shape, so the seams in the molded water-stop container 8 are connected to the container body 10.
and the lid body 11. Then, lid body 1
1 is formed into an inverted truncated cone shape, the lid II adheres tightly to the container body 10 due to its own weight, thereby suppressing the occurrence of gaps. That is, the water-stopping property of the water-stopping container 8 is extremely good, and the liquid-tightness in the disposal pit 7 is improved. In addition, in the construction method, the buffer material B is disposed of in the disposal pit 7 at the site.
Since it is molded integrally with the inner surface of the disposal pit 7, the structure inside the disposal pit 7 is strong and of constant quality, and there is no need to carry the pre-formed water stop container 8 (container main body 10) into the tunnel 1, making it more efficient. can do a good job.

Incidentally, the container body 10 is a solid package 12.
It is desirable to install the waste in the disposal pit 7 in advance before carrying it into the tunnel 1. In addition, in such a geological disposal facility, once the solidified material packages 12 are stored in all the disposal pits 7 of one disposal tunnel 4, this disposal tunnel 4
Furthermore, after all the disposal tunnels 4 have been backfilled, the main tunnel 6 and vertical shaft 3 are backfilled.

After checking the safety, all above-ground facilities such as the surface receiving facility 2 are finally dismantled and the geological disposal facility is closed.

In the above embodiment, the disposal pit 7 is provided on the floor of the disposal tunnel 4, but it may be provided on the side wall of the disposal tunnel 4, for example. Further, although the lid 11 is previously formed into an inverted truncated cone shape, it is not limited to this. For example, the opening 9 of the container main body IO is filled with powdered buffer material B, You may try to tamp it down.

"Effects of the Invention" As explained above, according to the geological disposal facility for radioactive waste of the present invention, a water-stop container formed by integrally molding a buffer material into a container shape is provided in the disposal pin, and radioactive waste is Since the solidified package of objects is stored, the water-tightness of the disposal pinto can be improved due to the excellent water-stopping properties of this water-stopping container. Further, according to the construction method of a geological disposal facility of the present invention, after filling the disposal pit with buffer material and solidifying it, storage holes are bored in the buffer material, thereby forming the buffer material on site. This allows us to improve work efficiency and ensure that the structure inside the disposal pin is strong and of constant quality. That is, according to the present invention, it is possible to prevent moisture from penetrating into the solidified material package as much as possible, thereby improving the integrity of the geological disposal facility.

[Brief explanation of the drawing]

1 to 11 show one embodiment of the present invention, FIG. 1 is a perspective view explaining the overall schematic structure, FIG. 2 is an enlarged view of the part indicated by the symbol ■ in FIG. 1, and FIG. The figure is a vertical cross-sectional view of a disposal pit, Figures 4 to 11 are vertical cross-sectional views of a disposal pit explaining the construction method of a geological disposal facility step by step, and Figures 12 and 13 are longitudinal cross-sectional views of a conventional geological disposal facility. 12 is a vertical sectional view of the tunnel and disposal pit, and FIG. 13 is a perspective view of the water stop block. 1... Mine shaft, 2... Surface reception facility, 3...
・Vertical shaft, 4...Disposal tunnel, 6...Main tunnel, 7...Disposal pit, 8...Water stop container, 9
... opening, 10 ... container body, 11 ... lid, 12 ... assimilate package, B ... buffer material, G ... ground. Figure 2 Figure 4 Figure 5 Earthwork Figure 8 Figure 9 Earthwork Figure 6 Figure 7 Figure 10 Figure 11 Figure 12 Figure 13

Claims (1)

[Scope of Claims] 1) In a geological disposal facility for radioactive waste in which radioactive waste is buried and disposed of in underground bedrock, a tunnel is provided in the bedrock, a disposal pit is provided on the inner surface of this shaft, and this A geological disposal facility for radioactive waste, in which a water-stop container made by integrally molding a buffer material into a container shape is installed in a disposal pit, and a solidified package of radioactive waste is stored in the water-stop container. 2) The water-stop container consists of a container main body having an opening at the upper end, and a lid fitted into the opening, and the lid has a shape in which the outer diameter gradually increases from the lower end to the upper end. A geological disposal facility for radioactive waste according to claim 1, characterized in that: 3) A disposal pit is excavated at the bottom of the tunnel provided in the underground bedrock, this disposal pit is filled with buffer material, and after this buffer material is solidified, a storage hole is made in the solidified buffer material. 1. A method for constructing a geological disposal facility for radioactive waste, comprising: drilling a hole, inserting a solidified radioactive waste package into the storage hole, and then closing the storage hole with a buffer material.