JPH0582920B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an in-rock storage facility for radioactive waste.

[Prior Art] High-level radioactive waste generated in the process of reprocessing spent nuclear fuel has high radioactivity over a long period of time and also has a large calorific value.
Therefore, in final disposal to isolate it from the human environment, we must first take sufficient safety measures such as vitrification, and then store and manage it for a certain period of time to eliminate radioactivity and heat generation. It is necessary to sufficiently attenuate the amount. The storage management of this radioactive waste is
It lasts for decades or hundreds of years,
Facilities for this purpose are required to be able to keep the radioactive waste in good health during that period, and to be able to cool the radioactive waste and attenuate its radioactivity without causing negative effects such as radioactive contamination on the surrounding environment. Ru.

As a facility for storing such radioactive waste, the applicant considered an in-rock storage facility D as shown in FIGS. 2 and 3. As shown in Figure 2, this in-rock storage facility D consists of a lower shaft 2, one end of which is open to the atmosphere, and a lower shaft 2, which is located almost parallel to the lower shaft 2, in a bedrock 1 forming a slope such as a mountainside. An upper shaft 3 is excavated, and the lower shaft 2 and the upper shaft 3 are communicated through a plurality of storage shafts 4 .
An exhaust shaft 5 is excavated almost perpendicularly from the upper shaft 3 and the upper end is open to the atmosphere, and each of the shafts forms a series of air flow passages. As shown in FIG. 3, solidified radioactive waste packages 6 are stored inside the storage shafts 4. The solidified body package 6 is made by vitrifying radioactive waste and then sealing it in a stainless steel container (canister). Note that radiation shield materials 7 and 8 are attached to the upper and lower ends of the storage shaft 4, respectively, to allow air to flow therethrough but to block radiation emitted from the solidified material package 6.

This in-rock storage facility D configured as described above has the excellent radiation shielding performance of the bedrock 1.
Radioactive waste can be stored for a long period of time without adversely affecting the ground, and the air inside the mine shaft is ventilated by natural drafts, allowing radioactive waste to be efficiently cooled. In other words, the exhaust shaft 5, like a general chimney, generates a natural ventilation force (so-called chimney effect) according to its height and the difference in specific weight (i.e., temperature difference) between the air inside and outside the shaft. As shown by the arrow in FIG. 4, the air in the mine shaft is discharged from the exhaust shaft 5 by wind power, and in conjunction with this, outside air flows into the shaft from the open end of the lower shaft 2. Since the outside air has a lower temperature than the air inside the mine shaft, this outside air passes through the lower shaft 2 and rises inside the storage shaft 4, and is absorbed into the solidified material package 6.
By passing around the solidified body package 6, the solidified body package 6 is cooled.

In this way, this in-rock storage facility D ventilates the air in the tunnel without requiring any power source, so radioactive waste can be constantly cooled without requiring operating costs. .

[Problems to be solved by the invention] In the conventionally considered in-rock storage facility D as described above, if the container (canister) of the solidified material package 6 is sound, radionuclides will be scattered into the tunnel. Furthermore, since the radiation emitted from the solidified material package 6 is shielded by the radiation shield materials 7 and 8, the interiors of the upper tunnel 3 and lower shaft 2 are not contaminated and safety is maintained. It is secured.

However, in the unlikely event that the canister is damaged due to an accident, the radionuclides will be carried by the air flow, pass through the radiation shield material 7, and flow into the upper tunnel 3. In addition, it is necessary for workers to enter the upper tunnel 3 to store or take out the solidified material packages 6 into the storage shaft 4, or to inspect and monitor the inside of the tunnel, so the workers may be exposed to radiation. It is also possible.

Furthermore, even if the canister is healthy, the upper tunnel 3 is not a favorable working environment because the air that has become hot after cooling the solidified material package 6 flows through it, making it difficult to work inside. It is considered deaf.

This invention was made in view of the above circumstances, and is an in-rock storage facility that prevents workers from being exposed to radiation even if the integrity of the solidified material package is impaired, and that allows a suitable working environment to be maintained. The purpose is to provide

[Means for Solving the Problems] The present invention provides an upper tunnel and a lower shaft that are spaced apart in the vertical direction in an underground bedrock, and communicates the upper shaft and the lower shaft with a plurality of vertical shafts. Air flows from the lower shaft to the upper shaft through the shaft, and a working shaft is provided in which radioactive waste is stored in the shaft and has a communication passage communicating with the shaft. are arranged independently for each shaft so as to communicate with the working shaft, and each communicating path is provided with a shielding means for preventing the passage of air and radiation.

[Function] In the in-rock storage facility of the present invention, the lower shaft, shaft shaft, and upper shaft serve as a series of air flow paths, and air circulates around the radioactive waste stored in the shaft shaft to cool it. . In addition, the working tunnel is used as a passageway for storing or removing radioactive waste from the shaft, or for inspection, etc.
The shielding means provided in the communication path connecting the working shaft and the shaft prevents air from entering the shaft and radiation from passing through, thereby maintaining safety and a suitable working environment within the working shaft.

[Example] Hereinafter, an example of the present invention will be described with reference to FIG. 1. FIG. 1 is a perspective view (perspective view) of the main parts of the in-rock storage facility C of this embodiment. In this figure, the same components as those of the storage facility D previously considered are given the same reference numerals as in FIGS. 2 and 3, and detailed explanation thereof will be omitted.

First, with reference to FIG. 1, the in-rock storage facility C of this embodiment will be explained. This storage facility C
is the conventional storage facility D (see Figures 2 and 3)
A solidification package 6 in which radioactive waste is sealed in a canister is stored in a storage shaft 4 that communicates a lower shaft 2 with one end open to the atmosphere and an upper shaft 3 leading to an exhaust shaft 5. It is something to do.

In this embodiment, the solidified material package 6 is stored in the storage shaft 4 while being stored in the storage cask 11. The storage cask 11 stores 14 to 21 solidified packages 6 (radioactive waste is vitrified and sealed in a canister), and has radiation shielding performance, and
Fins are formed on the outer surface to enhance the heat dissipation effect. In this storage facility C, the working tunnel 9
is located approximately midway between the upper shaft 3 and the lower shaft 2 and between another adjacent storage shaft 4, and is excavated approximately parallel to the upper shaft 3 and the lower shaft 2. Further, a storage chamber 4b is formed approximately midway in the vertical direction of the storage shaft 4, and this storage chamber 4b communicates with the working tunnel 9, and inside this storage chamber 4b, solidified material packages stored in storage casks 11 are placed horizontally. and stored. That is, the storage room 4b
serves as a storage section in the storage shaft 4, and
It serves as a communication path that communicates the storage shaft 4 and the working tunnel 9. The storage chamber 4b serving as a communication path is
As shown in FIG. 1, each storage shaft 4 is provided independently, and each storage shaft 4 and the working tunnel 9 are individually communicated with each other. A shielding material 10 is attached to the opening portion of the storage chamber 4b serving as a communication path on the working tunnel 9 side. This shielding material 10
A material capable of shielding radiation (such as concrete or clay) is used in the storage room 4b.
It is installed airtight to prevent air from flowing into the working tunnel 9. The work of storing the storage cask 11 in the storage chamber 4b involves placing the storage cask 11 on a trolley 12, placing the trolley 12 on a traveling trolley 13 that moves in the axial direction of the work shaft 9, and moving the storage cask 11 to a predetermined position. Storage cask 11 up to trolley 1
This is carried out by transporting the truck 12 along with the truck 12, and moving the cart 12 laterally. Storage cask 11 is storage room 4
After being transported to the storage room 4b and the working tunnel 9, the shielding material 10 closes off the space between the storage room 4b and the working tunnel 9. The casks 11 stored in the storage room 4b are cooled by low-temperature air rising inside the storage shaft 4 from the lower tunnel 2, similar to the conventional storage facility D described above, and the cask 11 is cooled by the air. further rises, passes through the upper shaft 3, and is discharged from the exhaust shaft 5.

Based on the above configuration, in this storage facility C, the air flow path for cooling the storage cask 11 and the work path are separated, and the worker can 2) There is no need to go inside. That is, the work of storing the storage cask 11 in the storage shaft 4 is carried out from the working tunnel.
This is done with the shielding material 10 open, and the storage cask 1
1 into the storage chamber 4b of the storage shaft 4. As soon as the work is completed, the shielding material 10 is closed to prevent air from flowing into the working tunnel 9 and to prevent radiation from passing through, thereby improving the safety of the working tunnel 9 and a suitable environment for working. Can be maintained. The work of taking out the storage cask 11 housed in the storage shaft 4 can also be performed from the working tunnel 9 in the same manner as described above, and normal inspections, monitoring, etc. can also be performed from within the working shaft 9.

In addition, the storage chambers 4b, which serve as communication paths between the storage shaft 4 and the working tunnel 9, are arranged independently for each storage shaft 4, and each storage chamber 4b is provided with a shielding material 10, so that the storage chambers 4b are already stored. The air that has cooled the radioactive waste from the storage room 4b that stores the cask 11 and the storage shaft 4 does not flow into the work shaft 9 through the storage room 4b whose shielding material has been opened for carrying-in work or the like.

In addition, since the cooling air flows in one direction from the lower shaft 2 to the upper shaft 3 through the storage shaft 4, in the storage room 4b where the shielding material 10 is opened as described above, the cooling air flows through the upper shaft 3. Also, the air that has passed through the storage shaft 4 in which the storage casks 11 are already stored, which is communicated through the lower shaft 3, does not flow into the working shaft 9.

Therefore, even when carrying in radioactive waste is carried out for a long period of time, air that has cooled the radioactive waste flows into the work shaft 9 from the storage shaft 4 in which the radioactive waste has already been stored. Therefore, the safety and suitable environment of the working tunnel 9 can be maintained.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in all of the above embodiments, the radioactive waste (solidified package) was cooled by ventilation using the natural draft of the exhaust shaft.
The air within the tunnel may be cooled and circulated using an appropriate cooling means. Moreover, the upper tunnel and the lower tunnel may not only extend in one direction within the bedrock, but may also be provided in a mesh shape, for example, to spread out in the horizontal direction. In addition, in the conventional storage facility D, the radiation shield materials 7 and 8 (see FIG. 3) installed between the storage shaft 4 and the upper tunnel 3 and lower tunnel 2 are Since there is no need for workers to enter the tunnel 3 and the lower tunnel 2, they may be omitted, or may be provided.

Although omitted in the above explanation, in the unlikely event that the integrity of the solidified material package is compromised and radionuclides are dispersed into the cooling air, measures must be taken to prevent that air from being emitted into the atmosphere. Of course, processing equipment such as high-performance filters are installed near the open ends of the exhaust shaft and the lower shaft.

[Effects of the Invention] As described above in detail, according to the present invention, when radioactive waste is stored in some of the shafts and radioactive waste is further stored in the remaining shafts, The shaft in which radioactive waste is stored and the working shaft can be shielded by the shielding means provided in the communication passage, and the communication passage in the shaft in which radioactive waste has already been stored and the remaining shaft can be shielded. Because the communication passages of the mine shaft are independent from each other, air that has cooled the radioactive waste can flow from the shaft where radioactive waste has already been stored into the working shaft through the communication passages of the remaining shafts. do not have.

Therefore, even if the radioactive waste that has already been stored is cooled by air circulation and carried into the remaining shaft, the air that has cooled the radioactive waste will Radioactive waste will not be allowed to enter the working tunnel through the communication path from the vertical shaft where radioactive waste is stored.

In addition, in the remaining shafts, the upper shaft and the lower shaft are in communication with the shaft where radioactive waste is already stored, but air flows in from the lower shaft and flows out to the upper shaft. This prevents air that has cooled the radioactive waste from entering the shaft during work from the upper shaft side.

From the above, according to the present invention, air that has passed through the shaft in which radioactive waste has already been stored does not flow into the shaft during work and the working shaft, and radioactive waste can be stored for a long period of time. Safety and a suitable working environment within the working tunnel can be maintained even when carrying in work is carried out.

[Brief explanation of drawings]

FIG. 1 is a perspective view (perspective view) of essential parts of an in-rock storage facility C according to an embodiment of the present invention. Figures 2 and 3 are diagrams showing a conventionally considered in-rock storage facility D, in which Figure 2 is a perspective view showing its overall schematic configuration, and Figure 3 is an elevational sectional view of its main parts. It is. C...In-bedrock storage facility, 1...Bedrock, 2...Lower tunnel, 3...Upper tunnel, 4...Storage shaft (vertical shaft), 6...Solidified body package (radioactive waste),
9... Working tunnel, 10... Shielding material (shielding means).

Claims (1)

[Scope of Claims] 1. An upper shaft and a lower shaft are provided vertically apart in the underground rock, the upper shaft and the lower shaft are communicated with each other by a plurality of shafts, and the shaft is passed from the lower shaft to the shaft. In addition to allowing air to circulate through the upper shaft, a working shaft is provided in which radioactive waste is stored in the shaft, and has a communication passage communicating with the shaft, and the communication passage is provided for each shaft. 1. An in-rock storage facility for radioactive waste, characterized in that the facilities are arranged independently so as to communicate with the working tunnel, and each communicating path is provided with a shielding means for preventing the passage of air and radiation.