JPS6245421B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an underwater shock absorbing device that absorbs impact energy caused by a fall of a heavy object or the like by utilizing the commonly practiced deformation of a material by plastic buckling. By allowing the cylinder or rectangular tube acting as a buffer material to undergo free plastic buckling without being subjected to water resistance during an impact in water, the shock absorber function can be fully performed. In particular, it relates to an underwater shock absorbing device prepared in case of a hypothetical fall accident of a spent fuel transport container (hereinafter referred to as a cask) in a nuclear power plant fuel pool.

Conventionally, shock absorbers that utilize plastic buckling deformation in the axial direction of cylinders have been commonly used in various fields, and are also used at nuclear power plants in fuel pools and equipment loading/unloading entrances in preparation for a hypothetical cask fall accident. However, the above-mentioned shock absorber used in a fuel pool is used when the cylinder is suddenly compressed during an impact underwater, and the water in the cylinder falls from above between the cask and the pool floor lining plate. By being trapped, the trapped water is compressed and acts as internal pressure on the cylinder, so the center of the cylinder bulges instead of the original plastic buckling deformation that forms wrinkles in the cylinder and absorbs impact energy. It is quite possible that it will eventually explode. Because the resistance force of water trapped inside the cylinder is not taken into consideration, buckling does not work effectively, and the structure is unable to absorb all of the impact energy during impact, so it functions as a shock absorber. It was not possible to accomplish this.

An object of the present invention is to provide an underwater shock absorbing device that is capable of absorbing all of the impact energy caused by a heavy object such as a cask by having a structure in which plastic buckling of a cylinder or a rectangular cylinder can work freely even underwater. .

In order to achieve the above-mentioned object of the present invention, the inventor pre-filled a gas such as air inside a cylindrical or rectangular tube that is a cushioning material, so that it can sit on the cylinder or corner when absorbing impact energy underwater. By preventing forces other than bending force, such as internal pressure, from acting, all impact energy can be effectively absorbed through plastic buckling deformation alone.

In other words, when water is trapped inside a cylinder or rectangular tube, the compressibility of the water is very small, so the volume of the water inside does not change upon impact, and the force that compresses the water increases the internal pressure of the cylinder or rectangular tube. It is quite conceivable that the cylinder or square cylinder will act as a gas, causing it to swell and eventually explode. However, by pre-filling a gas such as air inside the cylinder or rectangular tube according to the present invention, the intrusion of water can be eliminated and the large volume change of the gas can be used to fill the cylinder or rectangular tube. This is an underwater shock absorber that suppresses the pressure rise that occurs and makes it easier for normal plastic buckling to occur.

An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, the underwater shock absorber of the present invention has a large number of cylinders 1 arranged in a row between upper and lower mounting plates 2 and 3, and covered with a thin metal plate 4 at the outermost periphery. be. Hanging rings 5 are attached to each of the four corners of the upper mounting plate 2.

As shown in FIG. 3, the plurality of cylinders 1 have a corrugated shape like a bellows, and both ends are inserted into the recesses 7 and 8 of the upper and lower mounting plates 2 and 3, respectively. It is assumed that a fluid with a very low compressibility such as water is not injected into the cylinder 1. Further, a thin metal plate 4 is watertightly welded to the outermost periphery of the cylinder 1, that is, the outer periphery of the upper and lower mounting plates 2 and 3 so as to connect them and form a closed container. This metal plate 4 has a corrugated shape similar to the cylinder 1 described above.

Next, the effect will be explained. This underwater buffer device is installed, for example, underwater in a fuel pool of a nuclear power plant. It is used to prevent the pool floor from being damaged and leakage due to impact caused by falling heavy objects when handling heavy objects. That is, when a heavy object 9 falls onto the underwater shock absorbing device of the present invention as shown in FIG. 1, the impact first acts on the upper mounting plate 2. Next, the impact acting on the upper mounting plate 2 acts on the cylinder 1 and is absorbed by the plastic buckling deformation of the cylinder 1. This absorption ensures the integrity of the pool floor, etc. The plastic buckling deformation of the cylinder 1 can occur freely without resistance due to the confinement of a fluid with a very low compressibility such as water, since the metal plate 4 covers the cylinder 1 in a watertight manner. Therefore, it is possible to sufficiently absorb the impact caused by falling heavy objects and prevent damage to the pool floor.

Incidentally, the cylinder 1 may be a rectangular cylinder.

As explained above, the underwater shock absorbing device of the present invention is configured to sufficiently absorb the impact caused by falling heavy objects, thereby preventing damage to the pool floor, etc.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view showing an embodiment of the underwater shock absorbing device of the present invention, FIG. 2 is a top view of FIG. 1 as viewed in the direction of the - line arrow, and FIG. It is a longitudinal cross-sectional view which expands and shows a part. 1... Cylinder, 2, 3... Upper/lower mounting plate, 4...
metal plate.

Claims (1)

[Claims] 1. A large number of cylindrical bodies filled with gas and corrugated into a bellows shape are arranged in a row between the upper and lower mounting plates, and the outer periphery between the upper and lower mounting plates is watertight with a corrugated metal plate. An underwater shock absorbing device characterized by comprising: