JP2598880Y2 - Radioactive material storage and its 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 radioactive material container and its storage.

[0002]

2. Description of the Related Art Generally, radioactive materials such as spent nuclear fuel assemblies used in nuclear reactors are dismantled and reprocessed to extract useful materials such as plutonium.

Conventionally, when storing spent nuclear fuel assemblies, the spent nuclear fuel assemblies are put into a fuel pool of a reactor building, and radiation shielding and cooling are performed by water. In addition, it has been considered that the spent nuclear fuel assembly is housed in a tank-like container, and the space inside the tank is filled with helium gas and hermetically sealed.

On the other hand, FIG. 4 shows an example of a storage for storing a radioactive substance container such as a vitrified radioactive waste liquid. In this storage, a plurality of cylindrical containers 4 that can be hermetically sealed by a shielding plug 3 are suspended at intervals from a ceiling slab 2 of a cell room 1 surrounded by concrete walls. The radioactive substance storage bodies 5 are stored in a stacked state. In this case, in order to cool the radioactive substance storage body 5, the outer cylinder 6 surrounds the cylindrical container 4.
And surrounding the outer cylinder 6 is vertically divided by a horizontal partition plate 7, and the cooling air taken in from the intake port 8 is guided to the lower part of the cell chamber 1 by the intake path 9, and the cylindrical container 4 and the outer cylinder 6 are formed. A so-called natural ventilation, which is discharged from the exhaust shaft 11 through the ring-shaped cooling passage 10 between the two, is performed.

[0005]

[Problems to be solved by the invention] However, if the uranium fuel used in the light water reactor is oversupplied and its price is lowered, or if the practical use of the fast breeder reactor is delayed, economic efficiency will be reduced. It may be disadvantageous to immediately reprocess the spent nuclear fuel assembly in this respect. In such a situation, it is considered necessary to store the spent nuclear fuel assembly in a storage similar to the above storage as needed. In order to perform such storage, a thorough study is required on issues such as safety of radiation shielding, heat radiation, and handling of spent nuclear fuel assemblies having different dimensions due to differences in reactor types.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and a radioactive material container and a radioactive material container capable of coping with spent nuclear fuel assemblies having different dimensions and having improved radiation shielding properties and heat radiation properties. It is intended to provide storage.

[0007]

SUMMARY OF THE INVENTION A radioactive substance storage body according to the present invention is housed inside a cell room in a storage, and a spent fuel assembly is provided with a bottomed cylinder having an upper opening. The radiation shielding layer is formed by filling and solidifying the gap between the spent fuel assembly and the bottomed cylindrical container with a low-melting metal, and forming the radiation shielding layer at the top of the spent fuel assembly. Is adopted in such a state that the hanging portion of the pierce through the radiation shielding layer and protrudes upward . Also,
As a storage of the radioactive substance storage body according to the present invention, a cell chamber for storing the radioactive substance storage body, cooling air is sucked from an air intake disposed above the cell chamber, and the radioactive substance storage body is referred to as a cell chamber. A transfer chamber that takes in and out of the transfer chamber, an intake path that connects between the cell chamber and the transfer chamber to guide cooling air inside the transfer chamber to a lower portion of the cell chamber, and a radioactive substance storage that is connected above the cell chamber. as well as organic and an exhaust shaft for discharging air which has cooled the body, a support structure for supporting the weight of the radioactive material container is disposed within the cell chamber, in a state of penetrating in the vertical direction on the support structure A plurality of small holes provided to take in cooling air upwards, and a state in which cooling air around the radioactive substance storage is allowed to rise around the radioactive substance storage body arranged around the radioactive substance storage body stored inside the cell chamber. With steady rest member It adopts a configuration that.

[0008]

[Function] In the radioactive substance container according to the present invention, the spent fuel is used.
Radiation on the surface with radiation emitted from the charge assembly
The decay heat of the radioactive material is
Conducting heat through the shielding layer and the container and radiating heat to the outside
In a state where the surface of the radiation shielding layer is protected by the container
Then, it is stored in the storage. And spent fuel
The charge aggregate is removed from the storage as needed, and
Heating and melting the radiation shielding layer, which is a point metal
At the upper part of the spent fuel assembly.
By pulling, the container is pulled out from the upper opening of the container. Ma
In addition, the storage of the radioactive material storage
Air is guided from the transfer chamber to the lower part of the cell chamber through the intake path.
To cool the substance storage container and exhaust air
Discharged from the hood. Radioactive material collection inside the cell chamber
Delivery takes in cooling air upwards by support structure
As well as being supported by a steady member.
It is stopped, and radioactive material collection is
The cooling air around the container rises to cool.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a radioactive substance container according to the present invention.

FIG. 1 shows an embodiment of the radioactive material container 20, and FIG. 2 shows an embodiment of a storage 30 of the radioactive material container 20.

In the radioactive material container 20, a spent nuclear fuel assembly 21 is inserted into a bottomed cylindrical container 23 made of iron or the like, and a gap between these is filled with a low-melting metal such as lead, and the solidified solid is obtained by solidification. The radiation shielding layer 22 is formed.

The details of the radioactive material container 20 will be described.
Are provided in a protruding state, and a screw hole 27 is provided in an upper end surface of the hanging portion 24. The hanging portion 24 is set to penetrate the radiation shielding layer 22 and protrude upward.

The method for forming the radioactive material container 20 will be described. The male screw 26 at the tip of the hanger 25 is screwed into the screw hole 27 of the hanger 24 of the spent nuclear fuel assembly 21 and lifted up. The spent nuclear fuel assembly 21 is housed in a bottomed cylindrical container 23 having a desired outer diameter.
The molten metal having a low melting point is poured into the inside of the container 23 and solidified while being lifted so as to have a space between the container 23 and the inner bottom portion of the container 23, whereby an integrated product is obtained. Such a radioactive substance storage body 20 is covered with a thick radiation shielding layer 22, and a thick radiation shielding layer 22 is formed on the spent nuclear fuel assembly 21 such that the screw hole 27 is not buried. It is set as follows. The outer diameter of the container 23 is set to the same size regardless of the type of the spent nuclear fuel assembly 21 in consideration of the storage in the storage 22.

When taking out the spent nuclear fuel assembly 21 from the radioactive material container 20, the radioactive material container 20 is heated by a heater or the like while the hanging member 25 is engaged with the hanging portion 24 to reduce the melting point. Spent nuclear fuel assembly 21
Is lifted and pulled out of the container 23. The low-melting metal remaining on the surface of the spent nuclear fuel assembly 21 is removed, for example, by applying a centrifugal force in a melting tank.

According to the radioactive material container 20 having the above structure, the radiation emitted from the spent nuclear fuel assembly 21 is:
It is shielded by the radiation shielding layer 22. In addition, since the radiation shielding layer 22 is made of a low melting point metal, the radiation shielding layer 22 has better heat conductivity than the helium gas surrounding the spent nuclear fuel assembly 21 in the conventional radioactive material container, and has a high cooling performance. There is an advantage that the effect can be enhanced. Further, since the outer surface of the radioactive substance container 20 is covered with a container 23 made of iron or the like having a higher hardness than the low melting point metal, the outer surface of the radioactive substance container 20 is protected from being damaged. .

Next, the storage 3 of the radioactive substance storage body 20
An embodiment of the present invention will be described. Even in the storage 30 in this embodiment, the radioactive substance storage body 20 is stored inside the cell chamber 31 surrounded by the concrete wall, and the storage is performed by natural convection of air. There is a common part with the warehouse. However, the cooling air drawn into the transfer chamber 33 above the cell chamber 31 from the air intake port 32 is
The storage 3 in the example of FIG. 4 is directed to a lower part of the cell chamber 31 through an intake path 34 provided upright in the center of the cell chamber 31.
Different from 0.

The cell chamber 31 is provided with a plate-shaped support structure 35 for vertically dividing the cell chamber 31. The support structure 35 is provided with a plurality of small holes 36 penetrating vertically. I have. Above the support structure 35, two steady rest members 37 are provided in parallel with the support structure 35 at an interval, and each of the steady rest members 37 is, as shown in FIG. Are formed in a lattice shape having a plurality of through holes 38, and are fixed to the side walls of the cell chamber 31.

In the ceiling slab 39 which partitions between the cell chamber 31 and the transfer chamber 33, each through hole 3 of the
8, a charging hole 40 for communicating the cell chamber 31 with the transfer chamber 33 is provided, and the insertion hole 40 has a shielding plug 4 for shutting off the cell chamber 31 and the transfer chamber 33.
1 is fitted. Then, in order to store the radioactive substance storage body 20 in the storage 30, the shielding plug 41 at the place where the radioactive substance storage body 20 is stored is removed,
The radioactive material container 20 is lifted and moved by the transfer device 42 in the transfer chamber 33, and the input hole 40 of the ceiling slab 39 is
After placing on the support structure 35 through the through hole 38 of the steady member 37 inside the cell chamber 30, the shielding plug 41 is fitted into the input hole 40 again.

According to the storage 30, the cooling air guided from the transfer chamber 33 to the lower part of the cell chamber 31 through the suction passage 34 is passed through the small holes 36 of the support structure 35.
5, is cooled along the outer surface of the radioactive material container 20 while rising along the outer surface of the radioactive material container 20, and is then discharged from the exhaust shaft 43. At this time, the cooling air in the intake path 34 is transferred from the transfer chamber 33 to the cell chamber 31.
Since the convection always flows in the direction, dust and the like contaminated in the cell chamber 31 do not flow into the transfer chamber 33, and the radiation in the transfer chamber 33 is kept at a low level.

[Other Embodiments] In the radioactive substance storage container according to the present invention and its storage,
Is, it is possible to adopt the following technology. Next to container 23
The cross-sectional shape should be an arbitrary shape such as a square. Container 2
3. Provide fins on the outer surface and the like of 3. Hanging part 24
Provide a male screw instead of the hole 27. Instead of screws
In this case, the tip shape of the hanging tool 25 is a hanging ring or the like. Steady rest
The through hole 38 of the female member 37 has an arbitrary shape such as a circle.
When. Vent the support structure 35 with a grating plate or the like.
It must be composed of something with the property.

[0021]

[Effects of the Invention] The radioactive material container according to the present invention and its storage
According to the storage, the following effects are obtained. (1) Insert the spent fuel assembly into the container and dissolve
Fill the solidified low melting point metal and solidify it to form a radiation shielding layer
To accommodate spent fuel assemblies of different dimensions.
Radioactive material covered with a radiation shielding layer
The body can be easily configured and stored in the storage. (2) The radiation shielding layer is covered by a bottomed cylindrical container
This protects the radiation shielding layer during transport
The fuel assembly is double-covered to maintain safety
Is done. (3) Radiation from spent fuel assemblies consisting of metal
Since it is shielded by the line shielding layer, the radiation shielding effect
Can be enhanced. (4) The radiation shielding layer is made of a low melting point metal.
Heat generated by the spent fuel assembly
Transmitted and therefore sealed helium gas etc.
Compared to the radioactive material container of
Can be. (5) Manufacturing cost because expensive helium gas is not used
Can be reduced. (6) Heat the radiation shielding layer to dissolve it,
Lifting using the hanging part at the top of the spent fuel assembly
As a result, the spent fuel assemblies can be easily
You can get out. (7) In the storage, cooling air flows from the transfer chamber to the intake path.
To the bottom of the cell chamber to cool the material storage container.
And the cooled air is exhausted from the exhaust shaft.
Therefore, dust and the like contaminated inside the cell chamber
Radiation inside the transfer room to avoid getting inside
The level can be lowered. (8) Inside the cell chamber, the radioactive substance storage body has a support structure
Supported by the body and the steady rest
Due to the air permeability of the structure and steady rest, radioactive materials
The container is cooled and the radioactive material container is stored safely
can do.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing one embodiment of a radioactive substance container according to the present invention.

FIG. 2 is a front cross-sectional view showing one embodiment of a storage of a radioactive substance storage body according to the present invention.

FIG. 3 is a perspective view showing a radioactive substance container stored in a storage of FIG. 2;

FIG. 4 is a front sectional view showing an example of a storage of a vitrified body.

[Explanation of symbols]

 REFERENCE SIGNS LIST 20 Radioactive substance storage body 21 Spent nuclear fuel assembly 22 Radiation shielding layer 23 Container 24 Hanging part 25 Hanging tool 30 Storage 31 Cell room 33 Transfer room 34 Intake path 35 Support structure 36 Small hole 37 Sway-stop member 38 Through hole 39 ceiling slab 40 input hole 41 shielding plug 42 transfer device 43 exhaust shaft

──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. ⁶ Identification code FI G21F 9/36 501 G21F 9/36 541B 541 G21C 19/06 US (56) Reference JP-A-61-162797 (JP, A JP-A-52-6899 (JP, A) JP-A-52-131098 (JP, A) JP-A-59-58397 (JP, U) JP-A-57-20700 (JP, U) JP-A-5 81597 (JP, U) Japanese Utility Model 3-25199 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G21F 1/00-7/12 G21F 9/36 G21C 19/06

Claims (2)

(57) [Scope of request for utility model registration] 1. A cell room (31) in a storage (30).
A spent fuel assembly (21) inserted into a bottomed cylindrical container (23) having an open upper side, and The gap between the assembly (21) and the bottomed cylindrical container (23) is filled with a low melting point metal and solidified to form a radiation shielding layer (2).
2) A radioactive material container in which the suspended portion (24) above the spent fuel assembly (21) is projected upward through the radiation shielding layer (22) while forming 2). 2. A cell chamber (31) for accommodating a radioactive substance container (20), and a radioactive substance container for sucking cooling air from an air intake (32) disposed above the cell chamber (31). (20) a transfer chamber (33) for taking in and out of the cell chamber (31), and a cell chamber (31) and a transfer chamber (3).
3), an intake path (34) for guiding the cooling air inside the transfer chamber (33) to the lower part of the cell chamber (31), and a radioactive substance storage connected to the upper part of the cell chamber (31). Body (2
0) as well as organic and an exhaust shaft for discharging (43) the cooled air, is disposed within the cell chamber (31) radioactive material container (2
0), a support structure (35) for supporting the weight,
It is provided in a state penetrating the structure (35) in the vertical direction,
A plurality of small holes (36) for taking in air upwards;
Radioactive substance container housed inside cell chamber (31)
(20) is disposed around the radioactive material container (20).
Anti-sway member that allows rise of surrounding cooling air
(37) A storage for a radioactive substance container, comprising: