JPH03216596A - Container for radioactive waste - Google Patents

Abstract

PURPOSE:To prevent corrosion and to decrease capacity to be installed for a container handling device such as a crane in a facility by coating an outer surface of a steel container with an amorphous metal. CONSTITUTION:In a container 1 for radioactive wastes in this invention, a canister containing vitrified solid bodies of radioactive wastes is housed. After the canister 5 is housed, a lid body 4 is welded to a main body 2. On both outside surfaces of the main body 2 and the lid body 4, amorphous coatings are applied. In such a constitution, total weight goes upto 6,000kg, in an actual example, and goes upto 14,500kg if not with the amorphous coating. As shown in this constitution, by using this container for radioactive wastes, self-weight of the container can be decreased and therefore capacity for a container handling device to be installed such as a crane in a facility, can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a container for storing radioactive waste, and particularly to a container for geological disposal of radioactive waste.

[Prior Art] The basic concept of geological disposal of radioactive materials is to enclose them in a human barrier such as glass, canisters, and overbags, bury them in stable geological strata, and isolate them from the biosphere for a long period of time. Of the Greater Evalia, Overback requires reinforcement of the containment function of radioactive materials using glass and canisters during disposal, and the function of a pressure vessel against ground pressure.

Iron, copper, titanium, etc. are considered as overpack materials.

[Problem to be solved by the invention] These overback materials are required to have a service life of about 1,000 years, but in order to ensure such a service life, it is necessary to provide a corrosion allowance of several tens to 100 mm. It is expected that disposal costs will increase due to the increase in the diameter of the disposal tunnel. [Means for Solving the Problems] The radioactive waste container of the present invention is characterized in that the outer surface of the steel container is coated with amorphous metal. [Function] Amorphous coatings have excellent corrosion resistance, and by selecting an appropriate amorphous alloy according to the corrosive environment, there is almost no need to plan for corrosion of the structural material during the service life of the overback. , it is possible to significantly reduce the overpack wall thickness during manufacturing. [Example] Figure 1 is a longitudinal sectional view of a radioactive waste container 1 according to an example. This radioactive waste container 1 includes a bottomed cylindrical body 2 and a lid 4 attached to an upper opening 3 of the zero body 2. A tapered portion 3a is provided in the opening 3, and a tapered portion 4a of the lid body 4 engages with the tapered portion 3a.

A canister 5 containing vitrified radioactive waste is housed in the radioactive waste container 1 . After storing the canister 5, the lid 4 is welded to the main body 2.

The outer surfaces of the wooden body 2 and the lid body 4 are each coated with an amorphous coating.

FIG. 2 is a cross-sectional view showing an example of buried disposal of the radioactive waste container 1, in which the radioactive waste container 1 is buried in a disposal hole drilled in the bedrock 6. A cushioning material 8 is loaded around the periphery. 9 indicates a vitrified body of radioactive waste, and IO indicates a welded part.

In the above configuration, the inner diameter of the main body 2 is 440 mm.
, When the inner hole height of the zero body 2 after attaching the lid body is 1350 mm, according to the present invention, it is sufficient that the zero body 2 has an outer diameter of 860 mm and a height of 1600 mm, and the wooden body 2 and the lid body 4 are The total weight is 6000 kg.

On the other hand, when no amorphous coating is applied, the outer diameter of the main body 2 is 1160 mm, and the height of the main body 2 is 1900 mm.
mm, and the total weight reaches 14,500 kg. Note that the consideration conditions in this case are as follows.

1) The fi component is the ring-returning solidified product. 2) The container material is carbon steel, and in the case of the present invention, the surface is coated with a thickness of 20 mm.
Apply an amorphous coating of about μm.

3) The required wall thickness is 560 Kg/c based on the ground pressure.
In the case of rn', the body part is 210 mm and the lid part is 125 mm.
Let it be mm. (According to J46 of the 89th Autumn Conference of the Atomic Energy Society "Design Study of Carbon Steel Overback Based on Stress and Shielding Analysis") 4) Corrosion allowance is 150 mm for carbon steel (corrosion rate is 0.15 mm/Y, service life is tooO year).
In the case of an amorphous coating, it is Omm● In the present invention, the composition of the amorphous coating is M
-X or M-X-Y (M: base metal or alloy, X: metal providing corrosion resistance, Y: metalloid),
M is, for example, Fe, Ni, Cu or an alloy thereof;
As X, one or more of Cr, Ta, Ti, W, Zr, and Nb are used; as Y, P% B% C, etc. are used;
Those containing these in appropriate proportions are used.

In the present invention, it is preferable to select an amorphous composition depending on the corrosive environment. Specifically, if the buried environment is acidic such as hydrochloric acid or sulfuric acid, Ta-Fe-
It is preferable to use an amorphous Ni-Cr alloy.

Of course, the above-mentioned composition examples are illustrative of those which are particularly suitable for the present invention, and the present invention may also select amorphous compositions other than those mentioned above.

In the present invention, the thickness of the amorphous coating is 0.1~
The thickness is preferably about 30 μm, particularly about 10 to 20 μm.

[Effects] As described above, according to the present invention, the following effects can be obtained since there is almost no corrosion of the overpack. ■ By reducing the weight of containers, it becomes possible to reduce the capacity of container handling equipment such as cranes within the facility.

■ By reducing the size of the container, it becomes possible to reduce the diameter of the vertical hole and disposal tunnel of the disposal facility.

■ By reducing container dimensions, it is possible to increase the installation density of disposal tunnels.

■ Therefore, it becomes possible to reduce the total disposal cost of radioactive waste.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example, and FIG. 2 is a sectional view showing an example of burial disposal. 1...Radioactive waste container, 2...Wooden body, 4...
・Lid body.

Claims (1)

[Claims] A radioactive waste container characterized by having an amorphous metal coating applied to the outer surface of the steel container.