JP2003270385A - Radiation shielding device for spent fuel conveyance/ storage vessel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To store a spent fuel kept in a short period in a spent fuel pool and having a high dose rate of a radiation in a conveyance vessel and a storage vessel developed in recent years, capable of storing more spent fuel than a conventional vessel, and to provide a radiation shielding device capable of storing in the mixed state, the spent fuel kept in a long period and the spent fuel kept in a short period in the spent fuel pool. <P>SOLUTION: When the spent fuel kept in a short period in the spent fuel pool in a nuclear power plant and having the high dose rate of the radiation is stored, this radiation shielding device is stored so as to enclose the spent fuel stored in a basket of the vessel, to thereby shield neutron beams and γrays emitted from the spent fuel. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation shielding device relating to a container for transporting spent fuel generated in a nuclear power plant or a container for storage.

[0002]

2. Description of the Related Art Spent fuel transportation and storage containers are
These containers themselves have a shielding function like a neutron ray shield 17 and a γ ray shield 18 for protecting radioactivity in order to store spent fuel.

In the conventional transportation and storage containers for spent fuel, the number of fuel bodies that can be accommodated is small, and the neutron ray shield 17 and the γ ray shield 18 are thick, so that radiation can be shielded.

[0004]

The recently developed spent fuel transportation and storage containers have two to three times the number of fuel bodies that can be accommodated, which is why the spent fuel in these containers is increased. The neutron ray shield 17 and the γ-ray shield 18 are thinned in order to widen the place where the fuel can be stored.

Spent fuel is stored in a spent fuel pool of a nuclear power plant before being stored in a transportation container and a storage container.

After the spent fuel is stored in the transportation container or the storage container, the radiation dose rate on the surface of the container must be within the legal limit. Spent fuel pool from about 2 years to 3
Even if spent fuel stored for a short period of a year is stored, the radiation dose rate will be within the legal limit.

However, since the spent fuel to be stored in the transportation container or the storage container which has been developed in recent years is increasing and the neutron ray shield 17 and the γ ray shield 18 are thinned, the spent fuel is used in the nuclear power plant. Unless it is stored in the transportation container or storage container after being stored in the spent fuel pool for about 10 years for a long time, the radiation dose rate will not fall within the legal limit. There is a limit to the storage capacity of the spent fuel pool of a nuclear power plant, and this spent fuel pool contains both short-term and long-term storage periods, and these are transported. It must be transported in containers and stored in storage containers.

An object of the present invention is a transportation container and a storage container, which have been developed in recent years and can store a large amount of spent fuel compared to conventional containers, and can store spent fuel stored in a spent fuel pool for a short period of time. By doing so, it is an object of the present invention to provide a radiation shielding device for allowing mixed storage of spent fuel stored for a long period of time and spent fuel stored for a short period of time in a spent fuel pool.

[0009]

In order to achieve the above object, the present invention, as shown in FIG. 1, has a handle 1 at the upper part and a semi-part at the lower part of a prismatic column 2 having a size similar to that of spent fuel. Round sphere 3
Or with a cone attached downwards, γ
Enclose the radiation shielding material, the neutron radiation shielding material, or both.

In FIG. 1D, the rectangular column 2 itself is the γ-ray shielding material 4. In Fig. 1 (e), a neutron beam shielding material 6 is enclosed in a metal rectangular tube 5. In FIG. 1 (f), the prismatic column 2 encloses the neutron ray shielding material 6 in the γ ray shielding material 4. In Fig. 1 (g), the rectangular column 2 is a γ-ray shielding material 4
The γ-ray shielding material 7 and the neutron ray shielding material 6 which have better shielding ability than the γ-ray shielding material 4 are enclosed in the inside. 1 (d), (e),
(f) and (g) show types in which the contents of the prismatic column 2 are different.

The shape of the radiation shielding device is apparently
Since the shape is similar to the spent fuel, it may cause misunderstanding of fuel concealment during inspection by the International Atomic Energy Agency IAEA. Therefore, a hollow hole 8 is vertically provided inside the square column 2. Fig. 2 or a vertical recess 9 provided on a part of the side surface of the prismatic column 2 Fig. 3 or a part of the corner of the prismatic column 2 of Fig. 4 is vertically taken 10, different from spent fuel Shape it and eliminate the doubt of concealment.

A gamma ray shielding material, a neutron ray shielding material, or both of them are vertically enclosed in a cylindrical direction between cooling fins 21 of a transportation container and a storage container capable of storing a larger amount of spent fuel than conventional containers. A metal square member 15 can be attached to block radiation leaking from between the baskets 16.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 5 is a schematic view of the radiation shielding device of FIGS. 1 to 4 stored in a storage rack of a spent fuel pool of a nuclear power plant. By inserting the third portion of the radiation shielding device into the circular hole 12 formed in the lower portion of the storage rack 11, the radiation shielding device can be stored in the center of the storage rack 11.

A similar handle is attached to the spent fuel, and the handle 1 is used when the spent fuel in the fuel pool is grasped and moved by the fuel exchanger of the nuclear power plant. Figure 1
The handle 1 of the radiation shielding device in FIG. 4 can handle the radiation shielding device in the same manner in a facility that handles spent fuel.

FIG. 6 is a cross-sectional view of a transportation container and a storage container which have recently been developed and can store a large amount of spent fuel. When the spent fuel stored in the spent fuel pool of a nuclear power plant for a long period of time and having a weakened radiation is to be stored in the container, the spent fuel 14 is stored in all the lattices of the basket 16 of the container. When storing spent fuel that has strong radiation and is stored in the spent fuel pool for a short period of time, the radiation shielding device 13 of any of FIGS. 1 to 4 is stored in a lattice on the outer circumference of the basket 16 and used. By arranging so as to surround the fuel 14, neutron rays and γ rays emitted from the spent fuel can be shielded.

On the other hand, when both the short-term and long-term stored spent fuel are stored in the spent fuel pool, the spent fuel is surrounded by the lattice of the basket 16 storing the short-term stored spent fuel. 1 to FIG. 4 is housed in the radiation shielding device, or the spent fuel stored for a short period of time is moved to only one side of the transport container and the storage container, and the spent fuel stored for a short period of time is stored. The radiation shielding device of any of FIGS. 1 to 4 is housed in a lattice on the outer circumference of the container to shield neutron rays and γ rays.

6 and 7 is a structure in which the γ-ray shielding material, the neutron ray shielding material, or both are enclosed inside the rectangular tube of FIG. 6 (b). It shields radiation that leaks between the lattices of the basket 16.

[0018]

According to the present invention, when a nuclear power plant transports or stores spent fuel stored in a spent fuel pool for a short period and a long period of time, two types of containers for short and long periods are provided. It is possible to deal with these problems by using only one kind of container, which is a transportation container or a storage container that can store a large amount of spent fuel that has been developed in recent years without preparing. Further, similarly to the handling of spent fuel in the refueling machine of the spent fuel pool and the storage rack, the radiation shielding device of FIGS. 1 to 4 can be handled without changing the facilities of the nuclear power plant.

[Brief description of drawings]

FIG. 1 (a) is a perspective view of a radiation shielding device of the present invention. (b) Top view plan view of (a) above (c) Plan view of the lower field of view of (a) above (d) Cross-sectional plan view of (a) above (e) Another cross-sectional plan view of (a) above (f) Another cross-sectional plan view of (a) above (g) Another cross-sectional plan view of (a) above

FIG. 2 (a) is a perspective view of a radiation shielding device having a vertical hollow hole (b) above (a) a top view plan view (c) above (a) a bottom view plan view

[FIG. 3] (a) A perspective view of a radiation shielding device in which a vertical dent is provided in a part of a side surface of a prismatic column.

[FIG. 4] (a) A perspective view of a radiation shielding device in which some corners of a rectangular column are vertically taken (b) Above (a) Top view plan view (c) Above (a) Bottom view plan view

[Fig. 5] Conceptual diagram of shielding device stored in spent fuel storage rack of nuclear power plant (a) Radiation shielding device (b) Perspective view of spent fuel storage rack of nuclear power plant

[Fig. 6] (a) A cross-sectional plan view of a transport container or storage container capable of accommodating a large amount of spent fuel that has been developed in recent years. (B) Neutron ray shielding material or γ attached to the transport container or storage container. Cross-sectional view (15 cross-sectional view) of a metal square bar with wire shielding material or both inserted

FIG. 7 is a perspective structural view of a transportation container or a storage container that can store a large amount of spent fuel that has been developed in recent years.

[Explanation of symbols]

1 Handle 2 Square column 3 Insert into a spent fuel storage rack 4 γ-ray shielding material 5 Metal square cylinder 6 Neutron ray shielding material 7 γ-ray shielding material (material with better shielding ability than 4) 8 Hollow hole 9 Dent part on the side of prismatic column 10 Part of the corner of prismatic column taken vertically 11 Spent fuel storage rack 12 Hole for installing spent fuel at the center of storage rack 13 Transport container or storage Radiation shielding device 14 contained in a container 14 Spent fuel contained in a transport container or storage container 15 Radiation shielding device 16 for preventing radiation leakage from a lattice 16 Basket and its lattice 17 Neutron ray shielding material 18 γ ray shielding material 19 Metal square tube (γ ray shielding material) 20 Neutron ray shielding material or γ ray shielding material 21 Cooling fan

Claims (5)

[Claims] 1. A handle is attached to the upper part of a rectangular column in which a neutron ray shielding material, a γ ray shielding material, or both are inserted and sealed inside a rectangular cross section made of a metal square bar, and a semi-bottom is attached to the lower part. Radiation shielding device with a sphere or cone attached downwards. 2. The radiation shielding device according to claim 1, wherein a hollow hole is vertically provided inside the prismatic column according to claim 1. 3. The radiation shielding apparatus according to claim 1, wherein a side surface of the prismatic column according to claim 1 is provided with a vertical dent. 4. The radiation shielding device according to claim 1, wherein a part of the corner of the prismatic column according to claim 1 is vertically taken. 5. A transport container and a storage container to which a metal square bar in which a neutron ray shielding material or a γ ray shielding material or both are inserted vertically in a column direction between cooling fins.