JP2846540B2 - Container for producing vitrified radioactive waste - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art So-called transuranium elements contained in high-level radioactive waste discharged from a nuclear power plant or the like are recovered into uranium and plutonium, and then injected into a container as a glass melt. It is vitrified and stored in a container until the radioactivity level attenuates. Therefore, the container for injecting radioactive waste, as shown in Figure 1,
The shape did not consider taking out the solidified glass after solidification.

Further, from the viewpoint of long-term storage, the container is mainly made of stainless steel. When a high-temperature glass melt is poured into such a stainless steel container and solidified by cooling as it is, the vitrified material is firmly fixed to the inner wall of the container, and in combination with the above-described container shape, the vitrified material is discharged to the outside of the container. It was almost impossible to remove it.

[0004]

Accordingly, the above prior art has the following problems to be solved.

(1) The half-life of transuranium elements is generally about 10
At present, it is almost impossible to develop a storage container that is on the order of 100,000 years and can be used for more than 1 million years.

(2) If a defect such as corrosion or breakage of the container occurs during long-term storage, it is almost impossible to remove the vitrified material from the defective container and transfer it to another container. For this reason, the processing is performed by a method of transferring the defective container to a new container or the like, and a larger waste treatment facility is required.

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

[0008]

Means for Solving the Problems The present inventor has found that when a tungsten wire comes into contact with a scorched glass, it does not easily adhere to the glass, and even when the temperature of the glass drops to around room temperature, the tungsten wire can be easily removed from the glass. As a result of intensive studies, paying attention to the deviation, the present invention has been achieved.

That is, the present invention provides a compound represented by the general formula (1)

[0010]

## STR2 ## _{aM c O d · bW x O} y Formula (1) [In the formula, W is shown an elemental tungsten, O represents an oxygen element, M is Nb, Zr, Ni, Co, Cu, Mn , M
g represents an element selected from the group consisting of g, or a combination of two or more elements, a and b are integers or decimal numbers, a / b is in the range of 0 or more and 1 or less, and c and d are mainly M An integer value determined by the ionic valence,
x and y are integer values mainly determined by the ionic valence of W. ] Is a container for producing a vitrified radioactive waste vitreous body comprising the ceramics represented by the formula

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

[0012]

Hereinafter, the present invention will be described in detail.

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

The ceramics represented by the general formula (1) may be formed by powder metallurgy or by forming a metal film on the inner surface of a cast iron or stainless steel container by a conventional technique such as plating and vapor deposition, and then oxidizing and ceramicizing. It is preferable to line it as a ceramic film. The thickness of the ceramic film to be lined is preferably 10 μm or more. If the thickness is less than 10 μm, pinholes may be generated in the ceramic film.

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

It is preferable that the vitrified container is preheated before pouring the glass melt. The glass used for the vitrified body is often silicate glass, and its melting point varies depending on the content of silicic acid.
Since the temperature is as high as about 000 ° C., the preheating temperature is 500 ° C. or higher, preferably 5
It is preferable that the temperature is not lower than 00 ° C and not higher than 1000 ° C.

When a glass melt is poured into a 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 to pour the glass melt into two or more portions without pouring the glass melt into the container at once.

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

The temperature at which the vitrified product is taken out of the production container can be taken out if the temperature of the vitrified product is less than 400 ° C. 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 take out the vitrified body after lowering the temperature to 200 ° C. or lower.

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

[0021]

EXAMPLES The present invention will be described more specifically with reference to the following examples.

[0022] Example 1 Formula WO ₃ thickness by powder metallurgy using a powder material represented by 3 mm, 1 side 100mm, vitrified manufactured container 1 an open top of the positive cube height 100mm Prepared. On the other hand, it is made of stainless steel and has a thickness of 3 mm and a side of 102 mm.
A cubic container with a lid having a height of 102 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 vitrified container 1 kept at 500 ° C., and allowed to stand for one day and night to cool naturally. The temperature of the vitrified body after air cooling was 200 ° C. The workability when this was transferred to the storage container 2 is shown in Table 1.

Example 2 The inside of a cast iron cylindrical container having a thickness of 3 mm, a diameter of 100 mm, and a height of 150 mm and having an open upper portion was filled with Nb and W by 1%.
Plating at a ratio of / 10
A material indicated by Nb ₂ O ₅ · WO ₃ was lined to a thickness of 100 μm to manufacture a vitrified container 3. On the other hand, it is made of stainless steel and has a thickness of 3 mm and a diameter of 102 m.
A cylindrical container with a lid having a height of 150 mm and a height of 150 mm was manufactured as the storage container 4.

A glass melt containing radioactive waste at about 1000 ° C. was poured into a vitrified container 3 kept at 500 ° C., and left standing all day and night for natural air cooling. The temperature of the vitrified body after air cooling was 200 ° C. The workability when this was transferred to the storage container 4 is shown in Table 1.

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

Comparative Example Table 1 shows the operability when the same operation as in Example 1 was performed except that the material of the container 1 used in Example 1 was changed to stainless steel.

[0028]

[Table 1]

[0029]

According to the present invention, a container made of a material mainly composed of tungsten having no affinity for glass and having an inlet portion equal to or wider than the bottom portion is formed in the container by using the container as a container for producing a vitrified body. Since the vitrified material does not adhere to the inner wall of the container and can be easily transferred to another storage container, the following advantages are obtained by the present invention.

(1) The container for storing the vitrified body is corroded,
In the case of breakage, the vitrified body can be replaced at any time, so that it becomes easy to manage the vitrified body so that it does not escape from the storage container.

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

(3) The radioactive waste can be safely treated without developing a storage container that can withstand the tremendous years of the order of one million years.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a conventional vitrified radioactive waste container.

FIG. 2 is an image diagram showing one embodiment of a lined radioactive waste vitrified container.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vitrified body 2 Container main body 3 Lid 4 Lining material

Claims (2)

(57) [Claims] During 1. A general formula (1) ## STR1 ## _{aM c O d · bW x O} y Formula (1) [the above equation, W is shown an elemental tungsten, O represents an oxygen element, M is Nb , Zr, Ni, Co, Cu, Mn, M
g represents an element selected from the group consisting of g, or a combination of two or more elements, a and b are integers or decimal numbers, a / b is in the range of 0 or more and 1 or less, and c and d are mainly M An integer value determined by the ionic valence,
x and y are integer values mainly determined by the ionic valence of W. ] A container for producing a vitrified radioactive waste, comprising the ceramics represented by the formula: 2. The container for producing a vitrified radioactive waste according to claim 1, wherein the ceramic represented by the general formula (1) is lined inside the container.