JPH0829597A - Containing method of radioactive contaminant and container therefor - Google Patents

Abstract

PURPOSE:To enhance the cooling efficiency, the radioactivity shielding performance, and the impact resistance by containing a plurality of radioactive contaminants within a container while sectioning and integrating the container and the radioactive contaminants by filling a molten metal between them and solidifying. CONSTITUTION:Rectangular tubular frames 2 are supported by coupling frames 2a in a stainless steel container body 1A and the space part 3a between the container body 1A and the frame 2 is filled with molten metal, e.g. aluminum, having high thermal conductivity which is then cooled and solidified thus integrating the body 1A and the frame 2 through a cast metal layer M. A radioactive contaminant X, e.g. a spent fuel assembly, is then loaded into each frame 2 and an upper case 1B is applied to the body 1A and seal welded thereto. Subsequently, the space in the case 1B is filled with He gas thus forming a container P for radioactive contaminant. Since the decay-heat of the contaminant X is transmitted through the cast metal layer M to the container 1, heat radiation performance is enhanced. Radioactivity shielding performance is also enhanced because the metal layer M shields radioactivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of storing radioactive contaminants and a container for the same, and more particularly, to improve heat removal efficiency,
The present invention relates to a technique for reducing radiation leakage.

[0002]

2. Description of the Related Art High-level radioactive waste generated in a nuclear power plant or the like can be improved in handleability, for example, by vitrification treatment.

As an example of a storage for storing such radioactive waste such as a solidified package for a long period of time, there is an actual storage box of 31-252.
The techniques disclosed in Japanese Patent No. 99 and Japanese Patent Laid-Open No. 3-273193 have been proposed. In the former technology, a vitrified package is stored in a storage tube, and cooling air is inserted by natural convection around the storage tube to cool the vitrified package without using a forced circulation device. ing. In the latter technology, the spent fuel assemblies loaded in the canister are stored in the storage tube of the storage, and in addition to cooling by natural convection, the internal air of the storage tube is forcibly replaced to improve cooling efficiency. I have to.

[0004]

However, when a radioactive contaminant container such as a vitrified package or a spent fuel assembly is stored and cooled in a storage, the large-scale storage as in the prior art described above. Need to be built, and it is becoming increasingly difficult to secure a place to build it. Further, if the method of storing the spent fuel assembly in the fuel pool of the nuclear reactor until the time of reprocessing the same is limited by the storage capacity of the fuel pool.

The present invention has been made in view of the above circumstances, and aims to achieve the following objects. The first purpose is to ensure the cooling performance when the radioactive contaminant such as the spent fuel assembly is stored. The second purpose is to reduce the radiation leakage from the radioactive contaminant storage body and reduce the influence on the surrounding environment. A third object is to improve shock resistance, durability, etc. during storage and facilitate securing storage facilities or storage locations. The fourth purpose is to improve workability in extracting the radioactive contamination in a sealed state as needed.

[0006]

[MEANS FOR SOLVING THE PROBLEMS] As a method for storing radioactive contaminants, a plurality of radioactive contaminants are stored in a storage container in a partitioned state, and the storage container and the radioactive contaminants are placed between the storage container and the radioactive contaminants. The technology to fill and solidify the molten metal and integrate the whole is adopted. At that time, a plurality of tubular molds are stored in advance inside the storage container, and the space between the storage container and the tubular mold is filled with molten metal and solidified to integrate the whole. The storage method to be changed is applied. As a container for radioactive contaminants, a plurality of molds housed in a partitioned state inside the container, radioactive contaminants housed in a supported state by the molds, container and radioactive contaminants And a cast metal layer that fills the space between the two and integrates them by solidification. A plurality of cylindrical molds are used in the production of the radioactive contaminant container, and the container and the tubular container are in a state in which the radioactive contaminants are still loaded in the cylindrical molds in a removable manner. A technique of filling and integrating the space between the mold and the mold with a cast metal layer is adopted. As a radioactive contaminant storage body, a storage container, a radioactive contamination storage hole in a partitioned state formed by filling the inside of the storage container with molten metal, and a loaded state in the radioactive contamination storage hole A structure comprising a radioactive contaminant that is sealed in is adopted. As another radioactive pollutant container,
A configuration having a storage container, a radioactive contaminant stored in the storage container with a plenum portion left above, and a gas phase that fills the plenum portion and causes natural convection is adopted.

[0007]

The heat of the radioactive contaminants passes through the metal layer when the molten metal is filled and solidified around the plurality of radioactive contaminants loaded in the storage container in a partitioned state and the whole is integrated. And the uniform transmission, the cooling efficiency is improved, the shielding property is enhanced due to the radiation attenuation by the metal layer, and the mechanical strength such as impact resistance is improved. When filling the space between the storage container and the cylindrical formwork with molten metal, the formwork is used to align the positions of the radioactive contaminants, and the radiation level emitted from the storage container to the outside is made uniform. Planned. When the cylindrical form is applied, the radioactive contaminants are loaded or withdrawn as necessary with the cast metal layer disposed around the cylindrical form. In the case where the radioactive contaminant storage body is one in which the storage container is filled with molten metal to form the radioactive contaminant storage hole, the radioactive contaminant storage hole is It is loaded or withdrawn as needed. In the case where the radioactive contaminant storage body is one in which a natural convection gas phase is formed in the plenum portion above the inside of the storage container, the heat of the radioactive contamination is radiated by natural convection of the gas phase.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, with reference to FIGS. 1 to 4, respective embodiments of a method for accommodating radioactive contaminants and an accommodating body according to the present invention will be described.

FIGS. 1 and 2 show a first embodiment of a radioactive contaminant container according to the present invention, in which a spent fuel assembly or the like is placed inside a container 1 made of metal such as stainless steel. The radioactive contamination X of is stored. Prior to this storage, inside the container main body 1A of the storage container 1, as shown in FIG. 2, a rectangular frame-shaped mold 2 having a square cross section is connected to the connecting frame 2a.
Thus, the radioactive contaminants X are loaded in the mold 2 respectively to be in a state of being partitioned so that they are supported integrally. Each form 2 and the connecting frame 2a connecting between them are formed of a metal material such as stainless steel which is equivalent to that of the storage container 1. As shown in FIG. 1, the connecting frame 2a has a vertical interval. It is arranged in an empty state, and a through hole 2b is opened in the middle thereof. The through hole 2b
Is used for suspending an integrated structure of the mold 2 and the connecting frame 2a.

In the space 3 between the container body 1A and the mold 2,
A metal having a high thermal conductivity, such as aluminum or its alloy, is melted, and a molten metal is filled and cooled and solidified, so that the cast metal layer M is inserted between the container body 1A and the mold 2.
The integration is performed by.

Thereafter, radioactive contaminants X such as a spent fuel assembly are loaded into each of the molds 2 and the container body 1A is covered with the upper case 1B to be sealed and sealed. By enclosing an inert gas such as He in the space inside the upper case 1B, a radioactive contaminant container P having a gas phase G is formed above the cast metal layer M. It should be noted that the upper case 1B has a lifting tool 1C which is used when suspending the radioactive contaminant storage body P by remote control or the like.
Are arranged.

In the radioactive contaminant container P thus constructed, the cast metal layer M is formed around the plurality of partitioned radioactive contaminants X.
The heat of the radioactive contaminant X is the cast metal layer M having a large heat capacity.
The temperature of the outer wall of the storage container 1 is made uniform, and the air is cooled almost equally by the convection and radiation of the surrounding air.

Since the cast metal layer M surrounding each radioactive contaminant X serves as an excellent radiation shielding material, the radiation level of the radiation emitted to the outside of the radioactive contaminant container P can be significantly reduced. it can. In this case, the radiation level from each radioactive contaminant X to the outside is made uniform by setting the position of each radioactive contaminant X, that is, the position of each mold 2 and the material and thickness of the cast metal layer M. , It becomes easy to set within the management range. Further, the cast metal layer M enhances the mechanical strength of the radioactive contaminant storage body P and has excellent impact resistance, and protects the stored radioactive contaminant X from external force.

As described above, since the radioactive contaminant container P shown in FIGS. 1 and 2 has excellent radiation shielding property, high strength and impact resistance due to the cast metal layer M, it is stored. Is relatively easy, and is kept in a state isolated from the living area, for example, in the site of the nuclear power generation facility or in an appropriate place such as the above-mentioned storage.

In the case where the cylindrical mold 2 is used in the radioactive pollutant container P, in addition to the setting of the loading position of the radioactive pollutant X, for example, the spent fuel assembly It can be easily pulled out at the time of reprocessing or at the time of replacement due to the reduction of the radiation level of the radioactive contaminant X. In this case, the seal welding of the container body 1A and the upper case 1B is disassembled and the upper case 1B is removed.

Next, FIG. 3 shows a second embodiment of the radioactive contaminant container according to the present invention, in which a cast metal layer M is formed in advance inside the container body 1A, and the cast metal is also formed. In the layer M, a plurality of radioactive pollutant storage holes 4 such as a square are formed in a divided state, and the radioactive pollutant X such as a spent fuel assembly is placed in the radioactive pollutant storage holes 4. It is loaded and sealed according to the example of FIG. In the example of FIG. 3 as well, the radioactive contaminant X is loaded into the radioactive contaminant storage hole 4 or withdrawn as necessary.

On the other hand, FIG. 4 shows a third embodiment of the radioactive contaminant storage body according to the present invention. Inside the container body 1A of the storage container 1, radioactive contamination such as a spent fuel assembly is carried out. When the object X is loaded, a plenum portion 5 which is a relatively large space is left above and the plenum portion 5 is filled with argon gas, nitrogen gas or the like to cause natural convection. The gas phase G for forming is formed. In addition, in the inner bottom portion of the container body 1A, a cradle 6 for partitioning and supporting the radioactive contaminants X is arranged, and when the radioactive contaminants X are stacked in a plurality of stages, a spacer 7 is arranged between them. The radioactive contaminants X are set so as to ensure the horizontal and vertical intervals. In the radioactive pollutant container P, the gas heated by the heat generation of the radioactive pollutant X rises to the plenum portion 5, so that natural convection that cools and descends frequently occurs. The heat of the noble contaminant X is removed.
At this time, natural convection also occurs in the gas phase G in the range of the plenum 5 having a relatively large volume, and cooling is promoted.

[Other Embodiments] The present invention includes the following techniques. a) Apply to radioactive contaminants X such as vitrified solids other than spent fuel assemblies. b) The cross-sectional shape of the formwork 2 is other than a regular square. c) When the radioactive contaminant X that does not need to be reprocessed or taken out is to be sealed, the radioactive contaminant X supported by the mold 2 and the cast metal layer M should be integrated.

[0019]

EFFECTS OF THE INVENTION According to the method for accommodating radioactive contaminants and the accommodating body thereof according to the present invention, the following effects are exhibited. (1) By accommodating a plurality of radioactive contaminants inside the storage container in a partitioned state, and by filling and solidifying molten metal between the storage container and the radioactive contaminants to integrate the whole,
It is possible to increase the heat capacity of the cast metal layer, improve the heat transferability inside the storage container, and improve the cooling performance. (2) Due to the good radiation attenuation of the cast metal layer, the radiation leakage from the radioactive contaminant container can be reduced, the influence on the surrounding environment can be reduced, and the handleability can be improved. (3) By surrounding the radioactive contaminants with the cast metal layer, impact resistance and durability during storage can be improved and storage facilities or storage locations can be easily secured. (4) A plurality of tubular molds are stored in the storage container in a partitioned state, and the space between the storage container and the tubular mold is filled with molten metal and solidified to form an integral body by a cast metal layer. By adopting the technique, it is possible to set the position of the radioactive contaminants, reduce the interference between the radioactive contaminants, and set the radiation level emitted to the outside. (5) By loading radioactive contaminants into and from the cylindrical formwork, the workability of loading radioactive contaminants is improved, and the radioactive contaminants can be easily pulled out as necessary. You can (6) Due to the good heat dissipation and radiation shielding properties of the cast metal layer, it is possible to increase the storage density during storage and storage in the storage and storage facility. (7) The composite structure of the tubular form and the cast metal layer improves the mechanical strength to protect the radioactive contaminants, prevent the radioactive contaminants from being damaged by external force, and ensure soundness. can do.

[Brief description of drawings]

FIG. 1 is a front sectional view showing a first embodiment of a radioactive contaminant container according to the present invention.

FIG. 2 is a plan sectional view showing a first embodiment of the radioactive contaminant storage body according to the present invention.

FIG. 3 is a plan sectional view showing a second embodiment of the radioactive contaminant storage body according to the present invention.

FIG. 4 is a partially sectional front view showing a third embodiment of the radioactive contaminant storage body according to the present invention.

[Explanation of symbols]

 P Radioactive contaminant container X Radioactive contaminant 1 Storage container 1A Container body 1B Upper case 1C Lifting tool 2 Formwork (cylindrical form) 2a Connecting frame 2b Through hole 3 Space section 4 Radioactive contaminant storage hole 5 Plenum part 6 Cradle 7 Spacer M Cast metal layer G Gas phase

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Keigo Mio 1 Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Ishikawajima Harima Heavy Industries, Ltd. Yokohama Engineering Center (72) Inventor Hiroaki Kato Isogo-ku, Yokohama-shi, Kanagawa 8 Shinsugita-cho, a company owned by Toshiba Yokohama, Ltd. (72) Inventor Mina Hanada 8, Shin-Sugita-cho, Isogo-ku, Yokohama, Kanagawa Prefecture Company owned by a company Yokohama, Ltd.

Claims (6)

[Claims] 1. A plurality of radioactive contaminants (X) are stored in the storage container (1) in a partitioned state, and molten metal is filled and solidified between the storage container and the radioactive contaminants. A method for storing radioactive contaminants, characterized by integrating the whole. 2. A plurality of tubular molds (2) are stored in the storage container (1) in a partitioned state, and molten metal is stored in a space (3) between the storage container and the tubular mold. A method for storing radioactive contaminants, which comprises filling and solidifying to integrate the whole. 3. A plurality of molds (2) accommodated in the storage container (1) in a partitioned state, a radioactive contaminant (X) accommodated in the molds in a supported state, and a storage. A radioactive contaminant container having a cast metal layer (M) that fills the space (3) between the container and the radioactive contaminant and integrates them by solidification. 4. A plurality of cylindrical molds (2) accommodated in the storage container (1) in a partitioned state, and radioactive contaminants (X) removably loaded into the cylindrical molds. ) And a cast metal layer (M) that fills the space (3) between the storage container and the cylindrical formwork and integrates them by solidification. 5. A storage container (1), a radioactive contamination storage hole (4) in a partitioned state formed by filling the inside of the storage container with molten metal, and the inside of the radioactive contamination storage hole. And a radioactive contaminant (X) which is sealed in a loaded state. 6. A storage container (1), a radioactive contaminant (X) stored in the storage container with a plenum portion (5) left above, and natural convection filled in the plenum portion. And a gas phase (G) for producing a radioactive contamination container.