JPH0221297A - Support of cask - Google Patents

Abstract

PURPOSE:To diminish substantially the overturning possibility of a cask by providing a cylindrically shaped support into which a lower part of a cask is inserted, and a bottom part having a smooth and disc bottom having a larger diameter than that of the cask. CONSTITUTION:A cask support 1 is placed in a spent nuclear fuel storage pool located at an upper part of a nuclear reactor. Then a cask 4 is supported by inserting and placing the cask 4 into a supporting part 2. In case of severe swaying by an earthquake, the cask slides because a bottom part 3a of the cask support 1 is made of smooth components such as a stainless steel plate, and moves horizontally to some extent in the spent nuclear fuel storage pool and consequently a lateral swaying component is absorbed. Also for the reason that the bottom part 3a has a shape with a larger diameter than that of the cask 4, so-called swirling movement is generated and consequently the cask hardly overturns.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a cask support device that supports a cask containing radioactive materials.

(Prior art) Generally, at nuclear power plants, solid radioactive waste such as spent nuclear fuel, control rods, channel boxes, etc.
It is housed, transported, and stored in spent fuel transfer casks and solid waste transfer casks (hereinafter referred to as casks), which are formed into cylindrical shapes made of stainless steel or the like.

In nuclear power plants, such casks are stored upright in a spent nuclear fuel storage pool above the reactor building.

(Problems to be Solved by the Invention) As mentioned above, conventional casks are stored upright in the spent nuclear fuel storage pool at the top of the reactor building, and in particular, the equipment that supports the casks is It had not been used. For this reason, in the event of a major earthquake, for example, there is a possibility that the cask may fall over, and the inner wall of the fuel storage pool or the cask body may be damaged.

The present invention has been made in response to such conventional circumstances, and provides a cask support device that can significantly reduce the possibility of the cask falling over compared to the prior art, and can improve safety. This is what I am trying to do.

[Structure of the Invention (Means for Solving the Problems) That is, the present invention is an apparatus for supporting a cylindrical cask containing a radioactive substance therein, the cylindrical support into which the lower part of the cask is inserted. and a bottom portion having a circular and smooth bottom surface with a diameter larger than that of the cask.

(Function) The cask support device of the present invention having the above configuration includes a cylindrical support portion into which the lower part of the cask is inserted, and a bottom portion having a circular and smooth bottom surface with a diameter larger than that of the cask.

Therefore, the possibility of the cask falling down can be significantly reduced compared to the conventional method, and safety can be improved.

In other words, since the bottom has a circular bottom with a larger diameter than the cask, in the event of a severe earthquake, it will cause a so-called whirling motion along the periphery of the bottom, making it more likely to fall than if the bottom was rectangular. becomes very small.

In addition, since the bottom area is large, the possibility of the cask falling over if its center of gravity deviates from a stable position is extremely reduced. Naturally, the larger the diameter of this bottom, the better the stability, but the installation space will also increase. It is preferable that

Furthermore, since the bottom surface is made of a member with a smooth surface, it is easy to slip, and even when an external force is applied, it is easy to maintain the same state due to the law of inertia. In other words, even if a large horizontal motion is applied due to an earthquake, the horizontal motion transmitted to the cask is alleviated by the sliding of the bottom surface. The material for this bottom should be one that has low friction with the stainless steel pool floor and is resistant to fatigue even when subjected to impact from friction or rocking, such as tungsten or stainless steel. preferable.

(Embodiment) Hereinafter, one embodiment of the cask supporting device of the present invention will be described with reference to the drawings.

FIG. 1 and FIG. 2 show a cask support device according to an embodiment of the present invention. It consists of a disk-shaped bottom part 3 that is fixed. Also, the bottom surface 3 of the bottom 3 a i;! , for example, is made of a member with a smooth surface, such as a stainless steel plate.

That is, the inner diameter of the support part 2 is slightly larger than the outer diameter of the cask 4, which houses solid radioactive waste such as spent nuclear fuel, control rods, and channel boxes. The structure is such that the cask 4 can be easily inserted therein.

In addition, the height of the support part 2 is relative to the height of the cask 4.
For example, it is 1/3 to 1/2. Further, the diameter of the bottom portion 3 is at least larger than the diameter of the cask 4. Naturally, the larger the diameter of the bottom part 3, the better the stability, but the installation space increases.
．． It is preferable to set the diameter to 0 times. Furthermore, in order to improve stability, it is effective to make the entire cask support device 1 made of lead or the like to increase its weight, but since the weight of the cask 4 itself is sufficiently heavy, manufacturing costs etc. Therefore, it is preferable that the entire structure is made of iron or the like, and that only the bottom surface 3a is made of, for example, a tungsten plate or a stainless steel plate.

The cask support device 1 of this embodiment having the above-mentioned configuration is arranged in a spent nuclear fuel storage pool in the upper part of a nuclear reactor. Then, the cask 4 is supported by inserting it into the support part 2 from above.

If an earthquake causes severe lateral shaking,
Since the bottom surface 3a of the cask support device 1 is made of a material with a smooth surface, such as a stainless steel plate, slipping occurs.
It moves horizontally to some extent within the spent nuclear fuel storage pool to absorb this rolling component. In addition, since the bottom surface 3a has a circular shape with a diameter larger than the diameter of the cask 4, it does not cause a so-called whirling motion as shown in FIG. 3, and does not easily fall over. In addition, in FIG. 3, illustrated arrow A indicates the direction in which the cask 4 is likely to fall, and illustrated arrow B indicates the direction in which the cask 4 is likely to fall.
indicates the direction of whirling motion.

That is, according to the cask support device 1 of this embodiment described above, the possibility of the cask falling down can be significantly reduced compared to the conventional case, and safety can be improved. In addition, the structure is simple, and it can be used simply by placing it in the spent nuclear fuel storage pool, and there is no need to add other equipment or modify the cask 4.

[Effects of the Invention] As described above, according to the cask support device of the present invention,
The possibility of the cask falling over can be significantly reduced compared to the conventional method, and safety can be improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a cask support device according to an embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional view of the cask support device shown in FIG. 1, and FIG. 3 is a diagram for explaining the whirling phenomenon. FIG. 3 is a perspective view of a cask support device. 1・・・・・・・・・・・・・・・・・・Cask support device 2・・・・・・・・・・・・・・・・・・Support part 3・・・・・・・・・・・・・・・・・・Bottom 3a...
・・・・・・・・・・・・・・・Bottom surface (made of stainless steel) 4・・・・・・・・・・・・・・・・・・Cask applicant Japan Atomic Energy Corporation Applicant Toshiba Corporation

Claims (1)

[Claims] (1) A device for supporting a cylindrical cask containing a radioactive substance therein, the device having a cylindrical support portion into which a lower part of the cask is inserted, and a circular and smooth bottom surface with a larger diameter than the cask. A cask support device comprising: a bottom portion;