JPS61204599A - Storage facility in base rock of radioactive waste - 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 rock storage facility for radioactive waste.

[Conventional technology 1] High-level radioactive waste generated during the process of reprocessing spent nuclear fuel has high radioactivity over a long period of time,
Furthermore, the amount of heat generated is large.

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 sufficiently reduce its radioactivity and calorific value. It is necessary to attenuate it. The storage management of this radioactive waste is for a long period of time, from several decades to several hundred years, and the 11M stage is designed to keep the radioactive waste healthy during this period and prevent radioactive contamination from surrounding the environment. It is required to be able to cool radioactive waste and attenuate its radioactivity without adverse effects.

As a facility for storing such radioactive waste, the applicant considered a rock-based storage facility as shown in FIGS. 4 and 5. As shown in Figure 4, this rock storage facility 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 113 is excavated, and the lower shaft 2 and upper shaft 3 are connected through a plurality of storage shafts 4..., and the upper end of the upper shaft 3 is opened to the atmosphere almost at the center of gravity. 5, and each of the above-mentioned tunnels forms a series of air flow passages. As shown in FIG. 5, solidified radioactive waste packages 6 are housed inside the storage shafts 4. The solidified package 6 is obtained by vitrifying the tliDJ bamboo waste and then sealing it in a stainless steel container (canister). Furthermore, radiation shielding materials 7 and 8 are attached to the lower end J3 and the lower end of the storage shaft 4, respectively, to allow air to flow therethrough but to block radiation emitted from the solidified material package 6.

This rock-based storage facility configured as described above is
Due to the excellent radiation shielding performance of Bedrock 1, radioactive waste can be stored for a long period of time without any negative impact on the ground, and the air inside the tunnel can be ventilated by natural drafts, allowing radioactive waste to be efficiently cooled. be.

In other words, the exhaust shaft passage 5, like a general chimney, generates a natural ventilation force (so-called chimney effect) according to its height and the specific weight difference (i.e., temperature difference) between the air inside and outside the tunnel. Due to the wind force, the air in the tunnel is discharged from the exhaust chamber tunnel 5 as shown by the arrow in FIG. 4, and as a result, outside air flows into the tunnel from the open end of the lower tunnel 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, rises inside the storage shaft 4, and passes around the solidified material package 6, so that the solidified material package 6
will be cooled.

In this way, this rock-based storage facility ventilates the air inside the mine shaft without requiring any power source, so it is possible to constantly cool radioactive waste without incurring operating costs. .

[Problems to be Solved by the Invention] In the conventional rock-based storage facility as described above, if the container (canister) of the solidified material package 6 is healthy, radionuclides will not be scattered into the mine shaft. In addition, the radiation emitted from the solidified package 6 is
Since they are shielded by the John shield material 7.8, the interiors of the upper tunnel 3 and lower tunnel 2 are not contaminated and safety is ensured.

However, in the unlikely event that the canister is damaged due to an accident or the like, 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 shaft 3 to store or take out the solidified package 6 into the storage shaft 4, or to inspect and monitor the inside of the shaft, so the workers may be exposed to radiation. It is also possible.

In addition, even if the canister is healthy, the upper area rU3 is not a favorable working environment because air that has become hot due to the cooling Un flows through the solidified package 6, making it difficult to work inside this area. It is thought that there will be.

This invention was made in view of the above circumstances, and is a rock-based storage facility that prevents workers from being exposed to radiation even if the integrity of the solidified 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 shaft and a lower shaft that are spaced apart in the vertical direction in underground rock, and communicates the upper shaft and the lower shaft with one or more vertical shafts. In addition to allowing air to flow through the shafts, radioactive waste will be stored in the shafts, and a working shaft will be constructed that leads to the shafts.
A shielding means is provided between the working shaft and the vertical shaft to prevent air and radiation from passing through.

[Function] In the 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 into the shaft, or for inspection, etc., and the shielding means installed between the working shaft and the shaft is This prevents the inflow of air and the penetration of radiation to maintain safety and a suitable working environment within the working tunnel.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 3. Components shown in J5 in these figures that are similar to the previously considered storage installation MD described above are designated by the same reference numerals as in FIGS. 4 and 5, and detailed explanation thereof will be omitted.

First, referring to FIG. 1, an in-rock storage facility A according to a first embodiment of the present invention will be described. (Figure 1 is a t-sectional view of the main part of this in-rock storage facility.) This storage facility A
1 is a storage shaft 4 which communicates a lower shaft 2, one end of which is open to the atmosphere, like the conventional storage facility D (see FIGS. 4 and 5), and an upper shaft 3 leading to an exhaust chamber shaft 5. A solidified package 6 in which radioactive waste is sealed in a canister is housed inside. In this storage facility A, a working shaft N9 leading to the ground surface is excavated above the upper shaft 3 and approximately parallel thereto. Also storage shaft 4
A shaft 4a extends further upward through the upper shaft 3, and this shaft 4a communicates the working shaft 9 with the upper shaft 3. A shielding material 10 is attached to a portion where the shaft 4a connects with the working tunnel 9. This shielding material 10
is made of a material capable of shielding radiation (for example, concrete or clay), and is installed airtight to prevent air from flowing into the working tunnel 9 from the vertical shaft 4a. Note that the radiation shield material 7.8 (see Figure 5) installed between the storage shaft 4, upper tunnel 3, and lower shaft 2 in conventional storage equipment is omitted in this storage equipment A. has been done.

Based on the above configuration, in this storage facility A, the air flow path for cooling the solidified material package 6 and the work path are separated, and the worker can 2) There is no need to enter the mine shaft. That is,
The work of storing the solidified package 6 in the storage shaft 4 is as follows:
The work is carried out from the working tunnel 9 with the shielding material 10 open, and the solidified package 6 is guided down into the upper shaft 3fi3 of the shaft 4a1 and into 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. Can be maintained. The work of taking out the solidified package 6 stored 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. .

On the other hand, the solidified material package 6 is cooled in exactly the same way as in conventional storage equipment, in which low-temperature outside air that has flowed into the lower shaft 2 rises inside the storage shaft 4 as indicated by the arrow in FIG. 1 and is solidified. After the body package 6 is cooled, it flows in the upper tunnel 3 in a direction perpendicular to the plane of the paper in FIG. 1, and is discharged from the exhaust chamber tunnel 5.

In this way, in this storage facility A, even if the solidified package 6 loses its integrity, it will not have a negative impact on the workers (and the environment in the working tunnel 9 can also be maintained). can.

In addition, as explained above, the lower tunnel 2 and the upper tunnel 3
Since there is no need for workers to enter the storage shaft 4.
Although the radiation shield material between the tunnels 2 and 3 is omitted, it may of course be provided in the same manner as in conventional storage equipment.

Next, referring to FIG. 2, an in-rock storage facility B according to a second embodiment of the present invention will be described. (Figure 2 is a plan view of the main parts of this in-rock storage facility B.) This storage facility B differs from the storage facility A described above (see Figure 1) in that the solidified material package 6 is Being stored and stored within the cask 11, and the accompanying storage shaft 4, shaft 4a,
The only change is the shape and dimensions of the working tunnel 9, etc., and the rest is the same as the storage facility, so the following explanation will be omitted. Note that the storage cask 11 has a solidified package (radioactive waste is vitrified and
W to Nistar! It stores 14 to 21 pieces (closed type), has radiation shielding performance, and has fins formed on its outer surface to enhance its heat dissipation effect.

Next, with reference to FIG. 3, a rock artifact storage facility C according to yet another embodiment will be described. (Figure 3 is a perspective view of the main part of this rock-based storage facility C.) In this storage facility C, the working tunnel 9 is located approximately midway between the upper shaft 3 and the lower shaft 2, and is located adjacent to the upper shaft 3. It is located approximately midway between the other storage shafts 4, and is excavated approximately parallel to the upper shaft 3 and 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, the solidified material packages stored in the storage casks 11 are placed horizontally. placed and stored.

The work of storing the storage cask 11 in the storage room 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 working tunnel 9, and moving the storage cask 11 to a predetermined position. This is done by transporting the storage cask 11 along with the truck 12 until the point where the truck 12 moves laterally. When the storage cask 11 is transported to the storage room 4b, the space between the storage room 4b and the working tunnel 9 is opened by a shielding material 10. The casks 11 stored in the storage room 4b are transported from the lower shaft 2 to the storage shaft 1, similar to the storage facilities A and B described above.
The air that has cooled the cask 11 by being cooled by the low-temperature air rising inside the cask further rises, passes through the upper tunnel 3, and is discharged from the exhaust chamber tunnel 5.

In this way, also in this storage facility C, the air flow path for cooling the solidified material package and the working tunnel 9 serving as a working passage are separated, and 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 chamber tunnel, but the air inside the tunnel was cooled using an appropriate cooling means and the air was circulated. You may also let them do so. 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.

Although omitted in the above explanation, in the unlikely event that the integrity of the solidified package is compromised and radionuclides are released into the cold W air, measures must be taken to prevent the 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 chamber tunnel and the lower tunnel.

[Effects of the Invention] As described above in detail, according to the present invention, the air flow path for cooling radioactive waste and the working tunnel are separated, so safety in the working tunnel is improved. This has effects such as being able to maintain a suitable working environment.

[Brief explanation of the drawing]

1 to 3 are diagrams showing embodiments of the present invention. FIG. 1 is an elevational view of the main parts of the rock-based storage facility B according to the first embodiment of the present invention, and FIG. 2 is an elevational view of the main parts of the rock-based storage facility B of the second embodiment of the invention. FIG. 3 is a perspective view (perspective view) of the main parts of a rock storage facility C according to a third embodiment of the present invention. Figures 4 and 5 are diagrams showing a conventional rock-based storage facility, with Figure 4 being a perspective view showing its overall schematic configuration, and Figure 5 being an elevational view of its main parts. It is. A.8. C...Bedrock storage facility, 1...
・Bedrock, 2...Lower tunnel, 3...Upper tunnel, 4...Storage shaft (shaft), 6...
・Solid package (radioactive waste), 9...
- Working tunnel, 10... Shielding material (shielding means). Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] An upper shaft and a lower shaft are provided vertically apart in the underground bedrock, and the upper shaft and the lower shaft are connected by one or more shafts, and the insides of the upper shaft, lower shaft, and shaft are air-filled. A shield is provided to allow radioactive waste to flow, store radioactive waste within the shaft, provide a working shaft leading to the shaft, and prevent the passage of air and radiation between the working shaft and the shaft. An in-rock storage facility for radioactive waste, characterized by comprising a means.