JPH0452597A - Storage tank for radioactive fluid - Google Patents

Abstract

PURPOSE:To enhance the strength of a shielding wall and to easily assemble the shielding wall by arranging casings on the inside and the outside and fixing a plurality of shielding blocks each formed by filling a box-shaped body with a shielding material to the inner surfaces of the casings. CONSTITUTION:An inside shielding wall 3 and an outside shielding wall 4 are provided on the inside and outside of the storage tank main body 2 on a base plate 1 and constituted of inside and outside casings 5, 6 and the shielding blocks 7, 8 stacked along the inner surfaces of the casings 5, 6. The blocks 7, 8 are constituted by filling a box-shaped lining boxes 9, 10 composed of stainless steel with a shielding material 11 such as boron concrete. Therefore, even when external force such as an earthquake is applied, the possibility of the destruction of the shielding material is reduced and, as a result, the reliability of the shielding walls 3, 4 from the aspect of strength is enhanced. Further, the shielding walls 3, 4 can be easily assembled by simple work.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to a storage tank for radioactive fluid that has shielding walls on the inside and outside of a storage tank body, and particularly relates to a storage tank in which the shielding wall has high strength and its assembly. This invention relates to a radioactive fluid storage tank that is easy to store.

"Conventional technology" Generally, high-level radioactive solutions generated at spent nuclear fuel reprocessing plants, etc., decomposed with nitric acid, etc., are normally stored sealed in storage tanks surrounded by shielding walls. .

As a storage tank for such a radioactive fluid (the above-mentioned solution), a ring-shaped tank called an annular vessel is known.

Conventionally, this annular tank has been provided with shielding walls simply assembled with concrete blocks on the inside and outside of the annular storage tank body.

``Problems to be Solved by the Invention'' The conventional annular tank described above has a layered shape of the storage tank body, so it is easy to ensure criticality safety, and because it is annular, the installation space can be used effectively. Although it has excellent advantages, it has the following problems that should be improved.

That is, since the shielding wall is formed by simply combining concrete blocks, the reliability of the strength of the shielding wall against external forces is extremely low. In particular, if an earthquake or the like occurs at the location where the concrete block is installed, there is a risk that the concrete block will shake and collide with the main body of the storage tank, causing it to break and be destroyed.

The present invention has been made in view of the above-mentioned conventional problems, and is a storage tank for radioactive fluid that has shielding walls provided on the inside and outside of the storage tank body, in which the shielding wall has particularly high strength and is easy to assemble. The purpose is to provide a storage tank for radioactive fluid.

"Means for Solving the Problems" A radioactive fluid storage tank of the present invention is a radioactive fluid storage tank comprising a storage tank body that encloses a radioactive fluid and shielding walls are provided on the inside and outside of the storage tank, and the storage tank includes: The shielding wall is constructed by arranging casings on the inside and outside of the main body, and fixing a plurality of shielding blocks made of box-shaped bodies filled with shielding material to the inner surfaces of these casings. .

According to the radioactive fluid storage tank of the present invention, the shielding material is filled in the box-shaped body fixed to the casing. Therefore, even if an external force is applied due to an earthquake, the shielding material and the storage tank body Furthermore, even if the shielding material inside the shielding block is broken due to an impact such as an earthquake, the box-shaped body 1 prevents this shielding material from scattering.

Moreover, since the storage tank of the present invention has a divided structure in which the shielding wall is made up of a plurality of shielding blocks, the shielding wall can be easily assembled by fixing the shielding blocks to the casing in stages starting from the lower stage. I can do it.

"Example" An example of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 is a perspective view showing the entire radioactive fluid storage tank.

What is designated by the symbol I in FIG. 1 is a donut-shaped base plate. An annular storage tank body 2 is provided on this base plate l, located approximately on its center line. The storage tank main body 2 is made of stainless steel, for example, and has a hollow interior, and is adapted to be filled with radioactive fluid through an injection port 2λ.

Further, on the base plate l, an annular inner shielding wall 3 and an annular outer shielding wall 4 are provided, located on the inside and outside of the storage tank body 2, respectively.

These inner shielding walls 3 or outer shielding walls 4 are connected to inner casings 5 that are spaced apart from each other in the storage tank body 2.
Alternatively, it is composed of an outer casing 6 and a plurality of shielding blocks 7 or 8 stacked along the inner surface of these casings.

Here, the inner casing 5 and the outer casing 6 are the 11th! ! 0. As shown in FIG. 2, for example, cylindrical members 5a, 5b, 5c, 5d, 5e or cylindrical members 6a, 6b, 6c, 6d, 6e made of stainless steel are laminated and fastened by flanges with bolts 30. The height dimension of these cylindrical members corresponds to the height dimension of the shielding block 7.8.

Further, the shielding block 7.8 is constructed by filling a shielding material 11 such as boron concrete into a lining box 9.10 (box-shaped body) made of, for example, stainless steel. And the lining box 9.10 is the fourth
As shown in the figure, a stepped portion is formed on the edge so that it is shifted in the vertical and horizontal directions at the center of the thickness direction, and by fitting these stepped portions together, the They can also be closely connected to allow multiple installations.

In addition, these lining boxes 9. Spacers 12 and 13 are provided at four locations between the 100-yen sides of lO,
Screw seats 14.15 are formed at the ends of these spacers 12.13, looking towards the outside of the respective lining box 9.10.

Then, the casings 5 and 6 are attached to these screw seats 14 and 15.
(17.18) Screw the stud bolt 16 through the
By fastening the shielding blocks 7.8 to the casing 5.6, the shielding blocks 7.8 are fixed in close contact with the casing 5.6.

Also, what is indicated by the reference numeral 20.21 in FIG. 1 is an inner shield plate and an outer shield plate,
They are provided so as to cover the surface of the inner casing 5 or the outer casing 6, respectively. Further, in FIG. 1, the reference numeral 22 denotes an upper cover plate, which is provided to cover the upper part of the storage tank body 2 or the shielding walls 3 and 4.

According to the storage tank configured as described above, the storage tank main body 2
If a radioactive fluid is sealed inside, the radiation emitted can be blocked by the shielding wall 3.4 and the radioactive fluid can be safely stored.

According to this storage tank, the shielding material 11 is filled in a lining box 9.10 (box-shaped body) fixed to the casing 5.6. Therefore, even if an external force is applied due to an earthquake or the like, the shielding material II and the storage tank body 2 will not come into contact with each other. In addition, the shielding block 7 may be damaged due to shocks such as earthquakes.
．． Even if the shielding material 11 inside the lining box 9 is broken, the lining box 9
．． 10 prevents this shielding material from scattering.

Moreover, the shielding wall 3.4 of this storage tank can be easily assembled as follows. That is, first, the lower cylindrical members 5a, 6a constituting the casings 5, 6 are placed on the base plate 1, and these cylindrical members 5a,
A shielding block 7.8 is arranged on the entire inner circumference of the bolt 16.6a. Fix with nuts 17°18. After confirming that there is a sufficient gap between the shielding block 7°8 and the storage tank body 2, the cylindrical members 5b and 6 of the next step above are removed.
b and the corresponding shielding block 7.8 are fitted in the same way. Hereinafter, the same operation is repeated for the upper cylindrical member 5e,
By repeating up to 6e, the shielding wall 3.4 can be easily constructed.

According to the radioactive solution storage tank of this embodiment, the following effects are achieved.

First, even if an external force is applied due to an earthquake or the like, there is very little risk that the shielding material 11 will break, and even if it breaks, it will not scatter. Therefore, the effect that the strength reliability of the shielding wall 3.4 becomes extremely high is achieved.

Moreover, the shielding wall 3.4 can be easily assembled by simply arranging the shielding block 7.8 together with the cylindrical member that constitutes the casing 5.6 and attaching the bolts 16 etc. from the outside of the casing 5.6. Furthermore, since the assembly can be performed while checking the positional accuracy of each stage, the assembly accuracy is also very high.

In addition, in the case of this embodiment, the casings 5 and 6 have a split structure, which makes it easy to manufacture the members that make up the casings 5 and 6, and the cylindrical members that make up the casings 5 and 6 are combined by flange fastening. This has the effect that the flange portion also functions as a reinforcing rib, making it easier to obtain the required strength of the casing.

Furthermore, the shielding blocks 7.8 are laminated both vertically and horizontally to form the shielding wall 3.4, and since the shielding blocks 7.8 are very small, this Another advantage is that the handling of block 7.8 becomes much easier.

In addition, in the case of the above embodiment, the spacer 13 and the screw seat 14
Although the shielding blocks 7 and 8 are provided at four locations each, the number may be changed as necessary.

Further, the shielding material 11 is not limited to boron concrete, but other concretes, lead, etc. may be used.

"Effects of the Invention" According to the radioactive fluid storage tank of the present invention, there is extremely little risk that the shielding material will be destroyed even if an external force is applied due to an earthquake or the like.
Moreover, even if it breaks, it will not scatter. Therefore, the effect that the reliability of the strength of the shielding wall becomes extremely high is achieved.

Moreover, the shielding wall has the advantage that it can be assembled by a simple operation of fixing the shielding blocks to the casing in stages.

[Brief explanation of the drawing]

FIGS. 1 to 5 are diagrams showing an embodiment of the present invention,
Fig. 1 is a perspective view showing the entire radioactive fluid storage tank, Fig. 2 is a longitudinal sectional view of the storage tank, Fig. 3 is an enlarged view of the part indicated by the symbol ■ in Fig. 2, and Fig. 4 is a lining box ( FIG. 5 is a horizontal sectional view of the storage tank. 2... Storage tank body, 3. 4...shielding wall, 5゜B...casing, 7゜8...shielding block, 9゜0...box-shaped body (lining box) ・...shielding material.

Claims (1)

[Claims] A storage tank for radioactive fluid, comprising an annular storage tank body that encloses a radioactive fluid, and shielding walls provided on the inside and outside of the tank body, wherein a casing is arranged inside and outside the storage tank body. A storage tank for radioactive fluid, characterized in that the shielding wall is constructed by fixing a plurality of shielding blocks, each of which is a box-shaped body filled with a shielding material, to the inner surface of the casing.