JPH0582919B2 - - Google Patents

Description

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

[Conventional technology]

High-level radioactive waste generated during the process of reprocessing spent nuclear fuel has high radioactivity over a long period of time and also has a large calorific value.
Therefore, before 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 reduce its radioactivity and calorific value. It is necessary to sufficiently attenuate the The storage and management of this radioactive waste is a long-term process that lasts for several decades to hundreds of years, and the facilities for this purpose are designed to keep the radioactive waste in good health during this period, and prevent negative effects such as radioactive contamination on the surrounding environment. It is required to be able to cool radioactive waste and attenuate radioactivity without causing any adverse effects.

As a facility for storing such radioactive waste, the present applicant considered an in-rock storage facility B as shown in FIGS. 2 and 3. As shown in Figure 2, this in-rock storage facility B 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 material 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 B 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. 2, the air in the tunnel is discharged from the exhaust shaft 5 by wind power, and in conjunction with this, outside air flows into the tunnel 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 B ventilates the air in the tunnel without requiring any power source, so radioactive waste can be constantly cooled without requiring operating costs. .

[Problem that the invention seeks to solve]

The ventilation air volume in the tunnel in the above-mentioned in-rock storage facility B is determined mainly by the balance between the natural draft generated by the exhaust shaft 5 and the ventilation resistance generated when air flows inside the tunnel, as described above. It is something. Therefore, especially when the length of the lower shaft 2 and upper shaft 3 is excessively long compared to the length (height) of the exhaust shaft 5, or when there are many bends in these shafts, It is conceivable that the ventilation resistance becomes large compared to the natural ventilation force, and the amount of ventilation air required to sufficiently cool the solidified body package 6 (radioactive waste) cannot be obtained.

This invention was made in view of the above circumstances, and provides an in-rock storage facility that can secure sufficient ventilation airflow even in a tunnel with large ventilation resistance by increasing the natural ventilation force inside the tunnel. The purpose is to

[Means for solving problems]

This invention provides a series of tunnels in underground rock, each of which is open to the atmosphere with a difference in height at both ends, and where the upper open end is nearly vertical. Storing the waste without blocking the tunnel, allowing air to circulate inside the tunnel, and blocking the tunnel with a heat pipe with its heat absorption part near the radioactive waste stored in the tunnel. In addition, the heat dissipation section is arranged near the open end of the upper part of the tunnel without blocking the tunnel.

[Effect]

In the in-rock storage facility of this invention, the vertical part formed near the open end of the upper part of the tunnel generates a natural draft force similar to a general chimney, and the inside of the tunnel is ventilated by this ventilation force, thereby disposing of radioactive materials. Cool things down.

In addition, the heat pipe quickly transfers the heat released from the radioactive waste to the vicinity of the open end of the upper part of the tunnel, where the heat is radiated to cool the radioactive waste. Then, heat is radiated to the air in the vertical part of the shaft from a heat radiating section disposed near the open end of the upper part of the shaft, and the heated air rises inside the shaft and flows out to the outside. In this way, the air heated by the heat radiating part of the heat pipe quickly flows out to the outside, promoting the rise of airflow inside the tunnel, and increasing the natural ventilation force compared to the case without the heat pipe. I can do it. In addition, since the heat dissipation part is provided near the open end of the upper part of the tunnel, the air heated by the heat pipe can quickly flow out to the outside without being retained inside the tunnel.
Natural ventilation can be greatly improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a perspective view showing the overall schematic configuration of the in-rock storage facility A of this embodiment, but the same components as the previously considered in-rock storage facility B described above are shown in FIG. The same reference numerals as in FIG. 3 are given, and detailed explanation thereof will be omitted.

Similar to the conventional storage facility B (see Figs. 2 and 3), this storage facility A is a lower tunnel with one end open to the atmosphere in a rock 1 forming a slope such as a mountainside. 2, an upper shaft 3 located above it, a storage shaft 4 that communicates with the lower shaft 2 and the upper shaft 3, and a nearly vertical storage shaft 4 connected to the upper shaft 3 via a connecting shaft 3a. An exhaust shaft 5 is excavated, and a solidified package 6 in which radioactive waste is sealed in a canister is housed inside the storage shaft 4. In addition, the first
In the figure, 2a is the open end of the lower tunnel 2, and 5a is the open end of the lower tunnel 2.
Reference numeral 9 indicates an open end of the exhaust shaft 5, and reference numeral 9 indicates a door that normally closes off the upper shaft 2.

There is a heat pipe 1 in the tunnel of storage facility A.
0 is placed. The heat pipe 10 is an excellent heat pipe in which a heat medium sealed in a sealed tube evaporates at one end of the tube, absorbs heat from the surroundings, and liquefies this heat at the other end of the tube and radiates the heat. It has a heat transfer effect. This heat pipe 10 has a plurality of heat absorbing parts 10a (four in this storage facility A), each of which has a heat absorbing part 10a branched into a gap between the inner surface of the storage shaft 4 and the solidified material package 6. It is located in Moreover, the heat radiation part 10b is arranged near the upper end of the exhaust shaft 5 (slightly below the open end 5a).

Based on the above configuration, in this in-rock storage facility A, air in the tunnel is discharged from the open end 5a of the exhaust shaft 5 by the ventilation force generated by the exhaust shaft 5, similar to the conventional storage facility B. Outside air flows in from the open end 2a of the lower tunnel 2 and flows around the solidified material package 6, thereby cooling it.

In addition, the heat pipe 10 has a heat absorbing part 10a disposed in the storage shaft 4 that absorbs heat released from the solidified body package 6, and quickly transfers this heat to the heat radiating part 10b to radiate the heat. The surroundings of the solidified material package 6 are kept at a low temperature to promote its cooling.

Furthermore, since the heat dissipation section 10b of the heat pipe 10 is arranged near the upper end of the exhaust shaft 5 (slightly below the open end 5a), the heat emitted from the heat dissipation section 10b (indicated by the broken line arrow in FIG. 1) ), the surrounding air is heated, the temperature rises, the buoyancy increases, and the air is quickly discharged from the open end 5a. In this way, the air heated by the heat dissipation part 10b of the heat pipe 10 quickly flows out from the open end 5a, thereby promoting the rise of airflow in the tunnel, compared to the case where the heat pipe 10 is not provided. can increase natural ventilation. In addition, the heat dissipation part 10b is connected to the upper open end 5 of the tunnel.
Since it is installed near a, the air heated by the heat pipe 10 does not stay in the tunnel.
It can be quickly drained to the outside, and as a result, natural ventilation can be greatly improved.

In this way, since the heat pipe 10 directly cools the solidified material package 6 and increases the ventilation force of the exhaust shaft 5, in this rock storage facility A,
Even if the lower tunnel 2 and the upper tunnel 3 are long and have high ventilation resistance, a sufficient ventilation air volume can be ensured and the solidified body package 6 can be efficiently cooled.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the shape of the tunnel may be a series of tunnels that provide natural ventilation through a chimney effect. Various shapes can be considered.

〔Effect of the invention〕

As explained in detail above, according to the present invention, a rock is formed in the underground rock, with both ends open to the atmosphere with a difference in height, and the vicinity of the upper open end being almost vertical. A series of tunnels are provided, radioactive waste is stored in the tunnels without blocking the tunnels, and air is allowed to flow through the tunnels, and a heat pipe with its heat absorbing part is stored in the tunnels. The tunnel was placed near the radioactive waste, without being blocked, and the heat dissipation section was placed near the open end of the top of the tunnel without blocking it. The formed vertical part generates a natural draft similar to that of a general chimney, and this draft cools the radioactive waste by ventilating the inside of the tunnel, while the heat pipe cools the radioactive waste. The heat is quickly transferred to the area near the open end of the upper part of the tunnel.
In addition to cooling the radioactive waste by dissipating heat there, the air in the vertical part of the shaft is heated to promote the upward movement of the airflow, and the air is quickly discharged from the open end, which is faster than normal natural ventilation. It is possible to generate a large ventilation force, thereby ensuring a sufficient ventilation air volume even in a tunnel with large ventilation resistance, and has the effect of efficiently cooling radioactive waste.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the overall schematic structure of an in-rock storage facility according to an embodiment of the present invention. Figures 2 and 3 are diagrams showing conventionally considered in-rock storage facilities, with Figure 2 being a perspective view showing its overall schematic configuration, and Figure 3 being an elevational cross-sectional view of its main parts. be. A...In-bedrock storage facility, 1...Bedrock, 2...Lower tunnel, 2a...Lower open end, 3...Upper tunnel,
4...Storage shaft, 5...Exhaust shaft (vertical part),
5a...Top open end, 6...Solidified body package (radioactive waste), 10...Heat pipe, 10a
...Heat absorption part, 10b...Heat radiation part.

Claims (1)

[Claims] 1. A series of tunnels are constructed in the underground bedrock, with both ends open to the atmosphere with a height difference, and the upper open end is almost vertical, and radioactive waste is placed inside the tunnels. The above-mentioned tunnel is stored without blocking it, air is allowed to circulate inside the tunnel, and the heat pipe is placed with its heat absorbing part near the radioactive waste stored in the tunnel without blocking the tunnel. An in-rock storage facility for radioactive waste, further comprising: a heat dissipation section located near the open end of the upper part of the tunnel without blocking the tunnel.