JP3042151B2 - Spent nuclear fuel storage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry-type spent nuclear fuel storage for storing spent nuclear fuel from, for example, a nuclear power plant.

[0002]

2. Description of the Related Art In a nuclear power plant, an operation of sequentially replacing a nuclear fuel assembly mounted on a nuclear reactor with a new one according to a service life is performed. Spent nuclear fuel removed from the reactor continues to emit strong radioactivity and heat due to the destruction of fissile material. For this reason, water is generally submerged in a storage pool provided in the power plant and cooled.

In the case where spent nuclear fuel is submerged in a storage pool and cooled, cooling water is contaminated with radioactivity. For this reason, when the calorific value of the spent nuclear fuel falls below the standard, it is withdrawn from the storage pool as soon as possible, and it is selected whether to perform reprocessing or intermediate storage. To reduce storage costs.

The applicant of the present invention has proposed a dry type spent nuclear fuel storage suitable for the intermediate storage in Japanese Patent Application No. 60-3357. The structure of the previously proposed dry-type spent nuclear fuel storage will be briefly described with reference to FIG. In the previously proposed nuclear fuel storage, a space separated from the outside air by a partition wall 3 made of a radiation shielding material such as concrete is constructed underground, a handling area 4 is provided at an upper part of the space, and a storage cell is provided at a lower part. 5 is arranged.

[0005] The storage cell 5 forms a storage pit 5A by forming a vertical hole in, for example, a block made of concrete, in which the columnar container 1 shown in Fig. 4 is stored, and the spent nuclear fuel 2 is stored. I do. The handling area 4 has an overhead crane 6 and a self-propelled loading machine 7.
Using the self-propelled loading machine 7, the columnar container 1 is inserted into the storage pit 5A provided in the storage cell 5 through the hole formed in the floor of the handling area 4, and the columnar container 1 is standing vertically in the storage cell 5. Store 1 and save.

The upper and lower surfaces of the hole forming the storage pit 5A are open, and a gap is formed between the hole and the columnar container 1 such that air can flow therethrough. Therefore, the air warmed by the heat generated from the columnar container 1 moves upward in this gap, and a convection is formed. The convection cools the columnar container 1. The warm air exhaled from the storage pit 5A is collected under the floor of the handling area 4, and the warm air circulation path 8 formed between the side wall 4A of the handling area 4 and the bulkhead 3 is formed.
Through to the upper part of the handling area 4.

A heat exchange means 9 such as a heat pipe is provided above the handling area 4. The heat exchange means 9 absorbs the heat of warm air and cools the warm air. The other end of the heat exchange means 9 penetrates the partition wall 3 and is exposed to the outside air passage 11 to release heat to outside air passing through the outside air passage 11. The air cooled by the heat exchange means 9 is guided to the cool air circulation path 12 and transferred to the lower part of the storage cell 5, where it is stored in the storage pit 5A.
Sucked into the holes that make up. Thus, the previously proposed spent nuclear fuel storage circulates cooling air by natural convection in the space isolated by the partition wall 3 to cool the spent nuclear fuel 2 stored in the columnar container 1 and reduce the radioactivity to outside air. The structure is such that the rise in temperature is suppressed without leaking to the spent fuel, and the spent nuclear fuel 2 can be stored safely and at low cost.

[0008]

The spent nuclear fuel storage proposed above has a structure in which the handling area 4 and the storage cell 5 are stored in a space isolated from the outside air by the partition 3. Therefore, the space surrounded by the partition 3. However, there is a disadvantage that the volume of the battery increases. In other words, since the partition wall 3 is made of a radiation shielding material, if the used amount is large, the cost for the building increases. The warm air circulation path 8 and the cold air circulation path 1
Since 2 is formed around the outside of the handling area 4, the volume of the space surrounded by the partition wall 3 also increases at this point. There is also a disadvantage that the shape of the whole building becomes large.

An object of the present invention is to reduce the volume of the space surrounded by the partition walls 3, reduce the amount of radiation shielding material used, and also reduce the shape of the building, so that it is inexpensive. To provide a spent nuclear fuel storage that can be

[0010]

According to the present invention, only a storage cell is stored in a space constructed by a radiation shielding material, and a handling area is arranged outside a partition. According to the configuration of the present invention, only the storage cell needs to be stored in the space constructed by the radiation shielding material. Therefore, the volume of the space constructed by the radiation shielding material can be reduced.

Further, according to the present invention, a warm air collecting chamber provided below the floor of the handling area for collecting warm air, heat exchange means for cooling the warm air collected in the warm air collecting chamber, and a cool air feeding chamber provided on the lower surface of the storage cell And a cool air passage for sending cool air into the cool air supply chamber to constitute a spent nuclear fuel storage. According to the configuration of the present invention, the handling area is taken out of the space surrounded by the partition. As a result, the volume of the space surrounded by the partition wall made of the radiation shielding material can be reduced by the volume of the handling area. As a result, the amount of radiation shielding material used can be reduced, and cost reduction can be expected. In addition, since it is not necessary to form a warm air passage and a cool air passage outside the handling area, the overall shape of the building can be reduced.

[0012]

FIG. 1 shows an embodiment of the present invention. In the present invention, only the storage cell 5 is stored in the space constructed of the radiation shielding material, and the handling area 4 is provided outside the partition 3. That is, a space surrounded by the partition walls 3 is constructed underground, and a handling area 4 is constructed above the space. Holes are provided on the floor of the handling area 4 in the same arrangement as the arrangement of the storage pits 5A provided in the storage cells 5, and the columnar container 1 is inserted into the storage cells 5 through the holes.
Alternatively, the operation of pulling out the columnar container 1 from the storage cell 5 is performed using the overhead crane 6 or the self-propelled loading machine 7.
The metal plug 13 is always fitted in the hole formed in the floor of the handling area 4 and is kept closed.

The storage cell 5 has a storage pit 5A formed in a vertical direction on a block constructed of concrete, for example.
The columnar container 1 is inserted into the storage pit 5A, and the columnar container 1 is supported while maintaining a vertical posture. On the upper surface side of the storage cell 5, a warm air collecting chamber 14 is formed between the upper surface of the storage cell 5 and the partition wall 3 constituting the floor of the handling area 4, and between the lower surface of the storage cell 5 and the partition wall 3. A cool air supply chamber 15 is provided.

A cool air circulation path 12 connects the warm air collection chamber 14 and the cool air supply chamber 15, and a heat exchange means 9 such as a heat pipe is disposed above the cool air circulation path 12. One end of the heat exchange means 9 projects to the upper position of the cool air circulation path 12 to directly contact the warm air collected in the warm air collecting chamber 14, and the other end penetrates the partition 3 and is provided outside the partition 3 outside the outside air passage. Exposure to 11 The heat exchange means 9 is supported so as to be able to traverse in a direction crossing the outside air passage 11,
It is configured to be drawn into the maintenance room 16 as needed to perform maintenance. The outside air passage 11 is extended upward from the position of the heat exchange means 9 in order to enhance the exhaust efficiency, and is provided with an exhaust port 11A at the upper end.
The warm air is released. Outside air of the same amount as this exhaust amount is sucked from the intake port 11B, and when the sucked outside air passes through the heat exchange means 9, it is warmed by heat exchange and rises. Natural convection is generated by this upward air current, and the air inside the partition wall 3 is cooled.

That is, in the space surrounded by the partition walls 3, the heat coming from the spent nuclear fuel 2 (see FIG. 4) in the storage cell 5 warms the air in contact with the peripheral surface of the columnar container 1 and moves upward. The air warmed by this movement is collected in the warm air collection chamber 14. On the upper surface of the warm air collecting chamber 14, an inclined surface 14A is formed which gradually rises toward the installation position of the heat exchange means 9. The warm air is guided by the inclined surface and forcibly flows toward the heat exchange means 9 and contacts the heat exchange means 9.

The warm air is cooled by coming into contact with the heat exchange means 9, becomes cool air, and descends through the cool air circulation path 12. The cool air that has descended through the cool air circulation path 12 is sent into the cool air supply chamber 15, and the storage pit 5 </ b> A of the storage cell 5 is supplied from the cool air supply chamber 15.
The fuel is heated again, circulates in the same route as described above, and keeps cooling the spent nuclear fuel 2 by natural convection. FIG.
Shows a modified embodiment of the present invention. In this example, the columnar container 1
3 is stored in another container 17 as shown in FIG. 3, and the spent nuclear fuel 2 is stored in a double container to improve safety.

That is, as shown in FIG. 3, the container 17 has a length (for example, 7 to 8 meters) from the floor of the handling area 4 to the lower end of the storage pit 5A formed in the storage cell 5.
Having. Therefore, the container 17 is disposed so as to pass through the warm air collection chamber 14. The hole formed in the floor of the handling area 4 has a step portion 18 formed by a difference in diameter, and the container portion 17 is locked by the step portion 18 and supported in a suspended state. The metal plug 13 is fitted to the upper end of the container 17 to seal the container 17. The metal plug 13 is also formed with a stepped portion depending on the difference in diameter to prevent radiation from leaking to the outside. That is, since the radiation has the property of traveling straight, it is possible to prevent the radiation from leaking outside due to the presence of the step portion 18.

As shown in FIG. 2, by storing the columnar container 1 inside the container 17, it is possible to provide a highly safe storage with less radiation leakage. FIG. 2 also shows a case where the heat exchange means 9 is supported so as to be able to move in the vertical direction, and the heat exchange means 9 can be lowered by the crane 19. The other structure is the same as that of FIG. 1, and further description is omitted.

[0019]

As described above, according to the present invention, since only the storage cells 5 are housed in the underground space constructed of the radiation shielding material, the volume of the space surrounded by the partition walls 3 can be reduced. it can. As a result, the amount of radiation shielding material used can be reduced. Further, since no air flow passage is formed outside the handling area 2, the shape of the whole building can be reduced. Therefore, the benefit that the cost required for the building can be reduced is obtained.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a modified embodiment of the present invention.

FIG. 3 is an enlarged sectional view showing a part of the embodiment shown in FIG. 2 in an enlarged manner.

FIG. 4 is a perspective view for explaining a state where spent nuclear fuel is stored in a columnar container.

FIG. 5 is a sectional view for explaining a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Columnar container 2 Spent nuclear fuel 3 Partition wall 4 Handling area 5 Storage cell 6 Crane 7 Self-propelled loading machine 9 Heat exchange means 11 Outside air passage 12 Cold air circulation path 14 Hot air collection room 15 Cold air supply room

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G21F 9/36 G21C 19/06

Claims (1)

(57) [Claims] 1. A. First Embodiment B. a space constructed and isolated from the outside air by a partition wall composed of a radiation shielding material; B. a storage cell for supporting and storing the columnar container containing the spent nuclear fuel stored in this space in a vertical position; The upper surface of the storage cell, the ceiling surface of the space, and the partition
B. a warm air collection chamber that is substantially surrounded by the inner peripheral surface of the column and collects warm air heated on the peripheral surface of the columnar container; E. heat exchange means for cooling the warm air, one end of which is exposed to the outside air passage through the partition and the other end is located at a position in contact with the warm air collected in the warm air collecting chamber; Approach the space where the heat exchange means is installed
The heat exchanger provided and removed from its position
And the maintenance room that houses the stage, F. G. a cool air circulation path for guiding the cool air cooled by the heat exchange means downward from the warm air collection chamber; Provided between the lower surface of the storage cell and the partition,
And a cold air supply chamber for supplying cool air guided through the cool air circulation path to a lower portion of the storage cell.