JPH0360400B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention mainly relates to a method for treating radioactive waste in which high-level radioactive waste is sealed in a container.

"Prior Art" High-level radioactive waste is waste containing a large amount of fissile products produced when spent fuel extracted from a nuclear reactor is reprocessed. This highly radioactive waste is highly radioactive and generates heat as the fissile products decay.
Therefore, in order to safely manage high-level radioactive waste and dispose of it safely in the future, so-called vitrification is carried out, in which it is melted together with glass components (such as borosilicate) and solidified by pouring it into containers such as stainless steel. It will be done. The vitrified high-level radioactive waste is then stored in storage facilities until the fissile products have decayed enough to be safely disposed of. In this case, there are three requirements for storing vitrified high-level radioactive waste: In other words, shielding to prevent strong radioactivity from leaking to the outside; removal of heat generated by the decay of fissile products; and dual containment functions. Also, an air cooling system is usually used. Regarding the above, confinement using a single-layered container and a facility structure, that is, one in which the air that has cooled the single-layered container is discharged to the outside through a filter, and one in which the air is confined in a double-layered container can be considered.

``Problem to be solved by the invention'' However, in confinement by the combination of the above-mentioned single-layered container and facility structure, it is necessary to increase the thickness of this single-layered container in consideration of impact such as falling. As a result, the container is unable to absorb the strain caused by glass solidification after it is filled into the container, and large stresses are generated, leading to problems such as deformation of the container, cracking of the internal glass, and stress corrosion of the container. be.

On the other hand, in the case of a device to be confined in the double container, as shown in FIG. By covering the opening of the canister 1 with the inner lid 2 and welding it, then inserting the canister 1 into the repack body 3, and covering the repack body 3 with the repack lid 4 and welding, a double structure is created. Because it completes the container,
In addition to complicating the process, the canister 1 must be lifted and inserted into the repack body 3, which poses a problem in handling, and the gap between the canister 1 and the repack body 3 cannot be reduced, so heat It has poor conductivity and problems in terms of heat removal.

The present invention was made in view of the above circumstances, and
The goal is to simplify the process of sealing radioactive waste, eliminate the need for handling processes such as lifting, and make the gap in the double-walled bottle large enough to not become an obstacle for heat removal. I can do it,
Another object of the present invention is to provide a radioactive waste disposal method that can absorb distortion during solidification and cooling of molten glass and maintain the integrity of the glass and external container.

"Means for Solving the Problems" In order to achieve the above object, the present invention manufactures a container having a double structure bottle part in advance,
After filling the container with molten glass containing radioactive waste, a lid is welded to the opening of the container, and an overcap is then welded to the top of the bottle portion of the container.

"Operation" In the method of treating radioactive waste of the present invention,
By manufacturing a container with a double-walled bottle part in advance, the gap in the bottle part can be kept small to the extent that it does not become a hindrance to heat removal, and the wall thickness of the inner container of the bottle part can be thinned, and the above two points can be achieved. After filling a multi-layered container with molten glass, the lid and overcap are welded together to simplify the sealing process and reduce the handling process.

"Embodiment" Hereinafter, an embodiment of the present invention will be described based on FIGS. 1 to 4.

In the figure, reference numeral 10 denotes a container in which a bottle portion 11 has a double structure, and this container 11 is manufactured in advance at a factory. That is, the container 10 has an opening 1
The outer container body 15 wraps the lower side from the neck 14 of the inner container body 13 having the inner container body 13 having the inner container body 13 having the inner container body 13 having the inner container body 13 having the inner container body 13 having the inner container body 13 having the inner container body 13 having an inner container body 13 having an inner container body 13 and a lower side thereof. The bottle portion of the inner container body 13 is thin enough (for example, 1 to 5 mm) to absorb thermal strain after glass filling.
The outer container body 15 has a sufficient thickness (for example, 5 to 10 mm) to withstand external impact.
has. Furthermore, the inner and outer container body 1 of the bottle part 11
The gap between 3 and 15 should be small enough (for example, 1 to 3 mm) so as not to interfere with the removal of heat from the vitrified high-level radioactive waste, and a spacer (for example, 1 to 3 mm) should be provided to maintain this gap constant. (not shown)
is installed between the inner and outer container bodies 13 and 15. Further, if necessary, a nozzle 16 is provided on the shoulder of the outer container body 15 to adjust the atmosphere between the inner and outer container bodies 13 and 15, and the inside is supplied via the nozzle 16.
Helium gas or the like may be filled.

Opening 1 of the container 10 manufactured in this way
From step 2, molten glass 17 made by melting high-level radioactive waste together with glass components is poured and solidified. Next, the opening 1 of the internal container body 13
2 is covered with a lid 18, and the opening 12 and the outer periphery of the lid 18 are welded using a remote automatic welding device to complete the container 10.
Molten glass 17 is sealed inside. moreover,
An overcap 19 is placed on the top of the outer container body 15 of the container 10 and welded using a remote automatic welding device. This completes the double confinement of the vitrified material 17 and stores it in a storage facility.

As described above, high-level radioactive waste is processed, but in this case, after filling the container 10 with the molten glass 17, the lid 18 and overcap 19 are simply welded to create a complete double container. Since the structure (confinement) is completed, the conventional handling process such as lifting the container body 1 is no longer necessary, and the confinement process can be simplified. In addition, since the bottle part 11 is manufactured in advance to have a double structure at the factory, highly accurate processing is possible, and therefore the inner and outer container bodies 13, 1
5 can be made to a size that does not pose an obstacle to heat removal, and the thickness of the inner container body 13 can be reduced, so that the inner container body 13 can absorb thermal strain.
There is no adverse effect on the glass or the outer container body 15.

The container 10, lid 18, and overcap 19 are made of a corrosion-resistant metal such as stainless steel.

"Effects of the Invention" As explained above, according to the present invention, a container having a double-layered bottle part is manufactured in advance,
After filling the container with molten glass containing radioactive waste, a lid is welded to the opening of the container, and an overcap is then welded to the top of the bottle part of the container, making it a double-layered container. By filling the container with molten glass and then welding the lid and overcap, the process for enclosing radioactive waste can be simplified, and the handling process such as lifting the glass filled container, which was conventionally done, can be simplified. In addition, by manufacturing a container with a double-walled bottle part in advance, the gap in the bottle part can be kept small to the extent that it does not become an obstacle to heat removal, and therefore, sufficient heat transfer performance can be achieved. can be secured.
In addition, by making the wall thickness of the inner container of the bottle part thinner, the inner container can absorb thermal strain during solidification and cooling of the molten glass, suppressing glass cracking, and generating stress in the outer container. Therefore, the integrity of the glass and outer container can be maintained reliably.

[Brief explanation of drawings]

1 to 4 show an embodiment of the present invention, and FIG. 1 is a cross-sectional view after double confinement is completed;
Figure 2 is a cross-sectional view showing when molten glass is filled, Figure 3 is a cross-sectional view when the lid is welded, Figure 4 is a cross-sectional view when overcap is welded, and Figure 5 is a conventional double confinement container. FIG. 10... Container, 11... Bottle portion, 12... Opening, 17... Molten glass (vitrification), 1
8...Lid, 19...Overcap.

Claims (1)

[Claims] 1. Prepare a container with a double-walled bottle part in advance, fill this container with molten glass containing radioactive waste, cover the opening of the container with a lid and weld it, and then close the bottle part. A radioactive waste disposal method characterized by placing an overcap on the top and welding it.