JPH06222197A - Container for fabricating vitrified radioactive waste - Google Patents

Abstract

PURPOSE:To readily take out materials that are vitrified inside a container composed partially of ceramics represented by a specific formula by lining the inside of the container. CONSTITUTION:A ceramic, represented by the formula (M is more than one element selected from Nb, Zr, Ni and the like, (a) and (b) are each an integer or a decimal and 0<=a/b<=1, and (c) and (d) ((x) and (y)) are each an integer value determined by the valency of M(W)), is preferably formed either by powder metallurgy or by forming a metal coating over the surface of a container made of cast iron or stainless steel, then converting the coating into ceramics, and using it as a ceramics coating for lining 4. A container main body 2 has an inlet portion equal to or greater than the other portions in width and is preferably cylindrical or rectangular. The relation between the bottom surface and height of the container is preferably such that the ratio of a value converted into the diameter at a circle to the height is 0.25 to 5. To take vitrified materials 1 out of the fabricating container 2, the vitrified materials are preferably heated to or below 200 deg.C and transferred into a storage container.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for treating radioactive waste. In particular, the present invention relates to a container for producing a vitrified body of radioactive waste (hereinafter referred to as a vitrified body producing container).

[0002]

2. Description of the Related Art So-called transuranic elements contained in high-level radioactive waste discharged from nuclear power plants and the like are injected into a container as a glass melt after recovering uranium and plutonium, and in the container. It is vitrified and stored together with the container until the radioactivity level decays. Therefore, the container for injecting radioactive waste is
The shape was not considered to take out the vitrified body after solidification.

Further, from the viewpoint of long-term storage, stainless steel is mainly used for the container. When a high-temperature glass melt is poured into such a stainless steel container and cooled and solidified as it is, the vitrified body firmly adheres to the inner wall of the container, and in combination with the above-mentioned container shape, the vitrified body is exposed to the outside of the container. It was almost impossible to remove.

[0004]

Therefore, the above-mentioned prior art has the following problems to be solved.

(1) The half-life of transuranium elements is about 10
It is on the order of 0,000 years, and it is almost impossible at present to develop a storage container that can be used for more than 1 million years.

(2) When a defect such as corrosion or breakage of the container occurs during long-term storage, it is almost impossible to take out the vitrified body from the defective container and transfer it to another container. Therefore, the defective container is to be treated by a method such as transferring it to a new container, which requires a larger-scale waste treatment facility.

In view of the above problems, there is awaited a container for producing a vitrified body, which can take out the vitrified solidified in the container and transfer it to another container. An object of the present invention is to provide such a vitrified body producing container.

[0008]

Means for Solving the Problems The present inventor has found that when a tungsten wire comes into contact with a glass which has been burned, it is difficult to adhere to the glass, and even when the temperature of the glass drops to around room temperature, the glass is easily removed from the glass. As a result of intensive studies focusing on the fact that it is off, the present invention has been achieved.

That is, the present invention has the general formula (1)

[0010]

Embedded image aM _c O _d · bW _x O _y General formula (1) [In the above formula, W represents a tungsten element, O represents an oxygen element, and M represents Nb, Zr, Ni, Co, Cu, Mn. , M
1 is an element selected from the group consisting of g or a combination of 2 or more elements, a and b are integers or decimals, a / b is in the range of 0 or more and 1 or less, and c and d are mainly M It is an integer value determined by the ionic valence,
x and y are integer values mainly determined by the ionic valence number of W. ] It is a container for producing a radioactive waste vitrified body having the ceramics shown as a constituent element.

Further, the present invention includes a container for producing a radioactive waste vitrified body in which the ceramics represented by the general formula (1) is lined inside the container.

[0012]

The present invention will be described in detail below.

The ceramic constituting the container for producing a vitrified material of the present invention is represented by the above general formula (1). In the above general formula (1), a / b is particularly 0 or more and 0.5 or less, Further, it is more preferably 0 or more and 0.3 or less.

The ceramic represented by the general formula (1) is formed by powder metallurgy, or after a metal film is formed on the inner surface of a cast iron or stainless steel container by a conventional technique such as plating or vapor deposition, it is oxidized or made into a ceramic. It is preferable to line the ceramic film. The thickness of the ceramic coating to be lined is preferably 10 μm or more. This is because if the thickness is less than 10 μm, pinholes may occur in the ceramic film.

The shape of the container is preferably such that the inlet has a width equal to or larger than that of the other portions in consideration of the ease of taking out the vitrified body. Handling of vitrified materials,
From the viewpoint of storage, a columnar shape, a rectangular shape, a conical shape, a pyramidal shape or the like is preferable, and a cylindrical shape or a rectangular shape is particularly preferable. Further, regarding the relationship between the bottom surface and the height, in consideration of workability, it is preferable that the ratio between the value calculated as the diameter of the circle and the height is 0.25 or more and 5 or less. The thickness of the container depends on its size,
From the viewpoint of container strength and the like, it is preferably 2 mm or more. One embodiment of the container of the present invention is shown in FIG. FIG. 2 shows a vitrified body producing container in which the inside of a cylindrical container is lined.

The glass-solidified body producing container is preferably preheated before injecting the glass melt. The glass used in the vitrified body is often silicoborate glass, and its melting point varies depending on the content of silicic acid, but is about 1
Since it is a high temperature of around 000 ° C, the preheating temperature is 500 ° C or higher, preferably 5 ° C or less, so as not to cause a temperature difference as much as possible.
It is preferable that the temperature is from 00 ° C to 1000 ° C.

When the glass melt is poured into the container for producing a vitrified body, the temperature difference between the container and the melt is 500 ° C.
It is preferably less than. When the temperature difference is 500 ° C. or more, it is preferable that the glass melt is not poured into the container at one time but divided into two or more times.

The molten material poured into the vitrified body producing container is cooled by natural air cooling, forced air cooling or the like to become a vitrified material. The cooling means is not particularly limited.

As for the temperature at which the vitrified body is taken out from the production container, the vitrified body can be taken out if the temperature of the vitrified body is less than 400.degree. Operability when transferring to another storage container,
From the viewpoint of preventing the vitrified body from adhering to the inner wall of the transferred storage container, it is more preferable to lower the temperature of the vitrified body to 200 ° C. or lower and then take it out.

The storage container for storing the vitrified body taken out from the vitrified body producing container may be formed of conventional stainless steel, cast iron or the like in the same shape as the vitrified body producing container. However, from the viewpoint of operability, it is preferable to manufacture with a margin of 1 mm or more from the outer dimension of the obtained vitrified body.

[0021]

The present invention will be described in more detail with reference to the following examples.

Example 1 Using a powder material represented by the chemical formula WO ₃ , a container 1 for producing a vitrified body having a thickness of 3 mm, a side of 100 mm, and a height of 100 mm was formed by a powder metallurgical method and the upper part of the cube was opened. I prepared. On the other hand, with stainless steel, the thickness is 3 mm and the side is 102
A cubic container with a lid having a size of mm and a height of 102 mm was prepared and used as a storage container 2.

A glass melt containing radioactive waste at about 1000 ° C. was poured into a glass-solidified body producing container 1 which was kept at 500 ° C., and left to stand overnight for air cooling. The temperature of the vitrified body after air cooling was 200 ° C. Table 1 shows the workability when this was transferred to the storage container 2.

Example 2 The inside of a cast iron cylindrical container in which the upper part of a cylinder having a wall thickness of 3 mm, a diameter of 100 mm and a height of 150 mm was opened was set to 1 for Nb and W.
The chemical formula is 0.1 by plating at a ratio of / 10 and oxidizing the plating film.
A container 3 for producing a vitrified body was produced by lining a material of Nb ₂ O ₅ · WO ₃ to a thickness of 100 μm. On the other hand, stainless steel wall thickness 3mm, diameter 102m
A cylindrical container with a lid having a height of m and a height of 150 mm was manufactured as the storage container 4.

A glass melt at about 1000 ° C. containing radioactive waste was poured into a glass-solidified body producing container 3 kept at 500 ° C., and left to stand overnight for air cooling. The temperature of the vitrified body after air cooling was 200 ° C. Table 1 shows the workability when this was transferred to the storage container 4.

Example 3 Nb of Example 2 was mixed with Zr, Ni, Co, Fe, Cu and M.
The same operation as in Example 2 was performed except that n and Mg were respectively changed. The results are shown in Table 1.

Comparative Example Table 1 shows the workability when the same work as in Example 1 was performed by replacing the material of the container 1 used in Example 1 with stainless steel.

[0028]

[Table 1]

[0029]

EFFECTS OF THE INVENTION A container containing tungsten as a main component, which has no affinity for glass, and having an inlet portion equal to or wider than the bottom portion is used as a vitrified body producing container. Since the vitrified body does not stick to the inner wall of the container and can be easily transferred to another storage container, the present invention provides the following advantages.

(1) Corrosion of the vitrified storage container,
If it breaks, it can be replaced at any time, and it is easy to manage the vitrified material so that it will not escape from the storage container.

(2) No large-scale waste treatment facility is required.

(3) It is possible to safely dispose of radioactive waste without developing a storage container capable of withstanding the tremendous years of the order of one million years.

[Brief description of drawings]

FIG. 1 is an image diagram of a conventional radioactive waste vitrified body container.

FIG. 2 is an image view showing one embodiment of a lined radioactive waste vitrification container.

[Explanation of symbols]

 1 Vitrified 2 Container body 3 Lid 4 Lining material

Claims (2)

[Claims] 1. A general formula (1): aM _c O _d .bW _x O _y General formula (1) [wherein W represents a tungsten element, O represents an oxygen element, and M represents Nb. , Zr, Ni, Co, Cu, Mn, M
1 is an element selected from the group consisting of g or a combination of 2 or more elements, a and b are integers or decimals, a / b is in the range of 0 or more and 1 or less, and c and d are mainly M It is an integer value determined by the ionic valence,
x and y are integer values mainly determined by the ionic valence number of W. ] A container for producing a radioactive waste vitrified body having the ceramics shown as a constituent element. 2. The container for producing a radioactive waste vitrified body according to claim 1, wherein the ceramic represented by the general formula (1) is lined inside the container.