JPH08327791A - Storage pit for radioactive waste - Google Patents

Abstract

PURPOSE: To provide a new storage pit for radioactive waste which is capable of effectively suppress thermal degradation of the cooling air outlet shaft inner surface of the storage pit wherein high temperature cooling air flows. CONSTITUTION: A storage pit for radioactive waste is constituted by placing a concrete-made outlet shaft 6 for exhausting a high temperature air in a storage body on the concrete-made storage body for containing high temperature radioactive waste and for introducing outside air and naturally cooling the waste. A plurality of outside air introduction holes 10 are punched on the outlet shaft 6 for introducing outside air and a partition wall 9 made of corrosion resistive and thermal resistive material along the inner surface of the outlet shaft 6. Between the partition wall 9 and the outlet shaft 6, an air flow path 12 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage pit for safely storing radioactive waste remaining after reprocessing spent fuel in a nuclear power plant.

[0002]

2. Description of the Related Art Spent fuel generated during the operation of a nuclear power plant contains uranium and plutonium that can be reused as fuels, so once the nuclear fuel is reused for effective use of resources. A reprocessing process is carried out where the uranium and plutonium are sent to the processing facility.

In this process, the residual high level radioactive liquid waste is inconvenient to handle as a liquid, so that
After being mixed with glass raw materials and melted in a glass melting furnace, they are packed in a stainless steel canister (container: diameter about 0.4 m, height about 1.0 m), solidified, and processed into a stable form. After that, it will be transported to the underground disposal site with this canister and stored, but since this vitrified body generates high heat (90 ° C or more),
Before being transported to an underground disposal site, it is stored in a vitrified material storage facility (hereinafter referred to as a storage pit) provided separately from this disposal site for about 30 to 50 years and gradually cooled. ing.

As shown in FIG. 3, this storage pit has a storage room 2 in a concrete storage frame 1 constructed underground.
In this storage chamber 2, a plurality of tubular storage cells 4 accommodating the plurality of canisters 3 are arranged and stored in an upright state, and at the same time, a cooling air inlet formed in the storage frame 1 is formed. By introducing the outside air from 5, the storage room 2
This is to naturally cool the high temperature vitrified material stored inside.

[0005]

By the way, as shown in the figure, the cooling air which has cooled the vitrified body to a high temperature passes through the outlet shaft 6 provided in the concrete storage frame 1 to Although it will be exhausted from the cooling air outlet 7 provided at the top, the inner surface of the concrete shaft 6 is for preventing the deterioration of the concrete base material due to the cooling air that has become hot inside the storage chamber 2. To
Insulation material is attached. However, as described above, since this storage pit is used for a long time of at least 30 to 50 years, the heat insulating material itself gradually deteriorates during this period, and even when it deteriorates. However, there is a problem that the heat insulating material cannot be easily replaced due to radiation exposure. In addition, when providing such a heat insulating material, it is necessary to consider the earthquake resistance, so that a plurality of holding members and the like are required, and there is a drawback that the structure becomes complicated.

Therefore, the present invention has been devised to solve the above problems, and an object thereof is to effectively suppress thermal deterioration of the inner surface of the cooling air outlet shaft of a storage pit in which high temperature cooling air flows. It is to provide a new radioactive waste storage pit capable of.

[0007]

In order to achieve the above object, the present invention provides a concrete storage frame for accommodating high temperature radioactive waste and for naturally cooling it by introducing outside air. In a radioactive waste storage pit in which an outlet shaft made of concrete for exhausting high temperature air inside the body is erected, a plurality of outside air introduction holes for introducing outside air are formed in the outlet shaft and along the inner surface of the outlet shaft. A corrosion-resistant and heat-resistant partition wall is formed, and an air flow path is formed between the partition wall and the inner surface of the outlet shaft, and the partition wall is formed of stainless steel, and It is fixed to a plurality of anchor members provided on the outlet shaft side.

[0008]

Since the present invention is configured as described above, the partition wall on the inner surface of the outlet shaft is heated when the cooling air heated to a high temperature by cooling the high temperature radioactive waste passes through the outlet shaft. The air on the air flow path side formed between the wall and the inner surface of the outlet shaft is also heated, and this air rises in the air flow path. Then, along with this, the outside air flows into the air flow path from the outside air introduction hole to cool the outlet shaft and the partition wall. Therefore, an air layer in which the outside air flows is formed between the outlet shaft and the high-temperature cooling air flowing in the outlet shaft, so that thermal deterioration of the outlet shaft due to the high-temperature cooling air can be prevented.

[0009]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows the exit shaft portion of a storage pit according to the present invention. This outlet shaft 6
As shown in FIG. 3, at the upper end of the concrete storage skeleton 1, it is erected upright integrally therewith and is formed into a columnar shape having a rectangular cross-section, and while allowing high temperature air in the storage chamber 2 to pass through, As shown in FIG. 1, the two cooling air outlets 7 for exhausting the cooling air passing through the cooling air outlet 7,
7 are formed so as to face each other. Further, cover members 8 and 8 are formed around the cooling air outlets 7 and 7 so that outside air, rainwater and the like can be cooled by the cooling air outlets 7 and
The outlet shaft 6 is prevented from flowing into the outlet shaft 6.

A partition wall 9 is provided on the inner side of the outlet shaft 6 so as to be parallel to the inner wall with a space of several cm between the partition wall 9 and the outlet shaft 6. An air flow passage 12 is formed separately from the inside of the partition wall 9. The partition wall 9 is made of a material having excellent corrosion resistance and heat resistance, such as a stainless steel plate, and as shown in FIG.
Reinforcing rod in concrete base material of outlet shaft 6 (not shown)
It is firmly fixed to the outlet shaft 6 side by a rod-shaped anchor member 11 and the like that are connected to each other.

Further, the outlet shaft 6 is formed with a plurality of outside air introducing holes 10 inclined obliquely upward, and the outside air around the outlet shaft 6 passes through the outside air introducing holes 10 and flows toward the air flow passage 12 side. There is. Since the lower end of the partition wall 9 is bent and connected to the outlet shaft 6 side, the high temperature cooling air in the storage chamber 2 does not flow in. That is, the upper end of the air flow path 12 is open, while the lower end is closed.

In the above, first, as shown in FIG. 3, the specific gravity of the air in the storage chamber 2 of the storage pit is lightened because heat is taken from the cylindrical storage cell 4 side in which the canister 3 is accommodated and heated. After that, as shown by the arrow in the figure, it flows through the communication passage 13 connecting the storage chamber 2 side and the outlet shaft 6 to the outlet shaft 6 side. Since this flow causes a negative pressure in the storage chamber 2, outside air is sequentially introduced into the storage chamber 2 from the cooling air inlet 5 as shown by an arrow in the figure.

Next, the high-temperature cooling air flowing to the outlet shaft 6 side rises while passing through the partition wall 9 as shown in FIG.
7 will be released into the atmosphere. At this time, as shown in FIG. 2, when the partition wall 9 is heated by the high-temperature cooling air passing through the inside of the outlet shaft 6 to heat the air on the side of the air passage 12, the inside of the storage chamber 2 is heated. Similar to the cooling air, the specific gravity becomes lighter to rise in the air flow path 12, merge with the cooling air flowing in the partition wall 9, and be discharged into the atmosphere from the cooling air outlets 7, 7. And
Since the outside air flows into the air passage 12 from the outside air introduction hole 10 by the released amount, the air passage 1
The inside of 2 is always cooled, and the heat from the partition wall 9 side is not transferred to the outlet shaft 6 side.

As described above, according to the present invention, the outside air introducing hole is formed in the outlet shaft, the partition wall is provided on the inner surface of the outlet shaft to form the air passage, and the outside air is introduced into the air passage. The outlet shaft is effectively insulated,
The thermal fatigue can be prevented. Further, since this partition wall is firmly connected to the outlet shaft side via the anchor, it also exhibits excellent vibration resistance.

[0016]

In summary, according to the present invention, it is possible to exhibit excellent heat insulating effect and vibration resistance with a simple structure, so that the life and reliability of the outlet shaft are greatly improved. Exert.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a partially enlarged view showing a portion A in FIG.

FIG. 3 is an overall view showing a configuration of a conventional storage pit.

[Explanation of symbols]

 1 Storage Frame 6 Outlet Shaft 7 Cooling Air Outlet 9 Partition Wall 10 Outside Air Introduction Hole 11 Anchor Member 12 Air Flow Path

Claims (2)

[Claims] 1. Containing hot radioactive waste, and
In the concrete storage skeleton for naturally cooling it by introducing outside air, in the radioactive waste storage pit where a concrete exit shaft for exhausting the high temperature air in the storage skeleton is erected, in the exit shaft, Along with forming a plurality of outside air introducing holes for introducing outside air, along the inner surface of the outlet shaft, a partition wall made of a corrosion resistant and heat resistant material is formed, and an air flow path is formed between the partition wall and the outlet shaft. Storage pit for radioactive waste characterized by being formed. 2. The radioactive waste storage pit according to claim 1, wherein the partition wall is made of stainless steel and is fixed to a plurality of anchor members provided on the outlet shaft side.