JP2014035194A - Heavy load fall-prevention rack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device (rack) capable of preventing a fall of a heavy load without a large structural change of a whole rack.SOLUTION: A heavy load fall-prevention rack includes: a base 1 on which a radioactive material container is mounted; supporting legs 4 provided to four corners of a bottom face of the base; a predetermined-size space formed between the bottom face of the base and a floor surface 5 by the supporting legs; and a high friction member which is provided right under the radioactive material container and to the bottom face of the base and whose contact area with the floor surface has a higher friction coefficient than the contact area of the supporting legs.

Description

  The present invention relates to a heavy load fall prevention stand.

  After being used in a nuclear power plant reactor for a certain period, spent fuel taken out from the core is stored in a spent fuel storage pool in the power plant for a predetermined period. The spent fuel whose predetermined cooling period has ended is stored in a radioactive material storage container (hereinafter referred to as a cask) having a radiation shielding performance in order to recover reusable nuclear fuel materials such as uranium and plutonium. And transported to fuel reprocessing facilities and radioactive material storage facilities by ship.

  The cask transported to the radioactive material storage facility is stored in the radioactive material storage facility for a certain period until the spent fuel is reused.

  Although this spent fuel is used, it is not only highly radioactive but also generates considerable heat, so the cask is a cylindrical, tough, large metal container with radiation shielding, sealing and cooling functions. ing. Therefore, the size and weight of this large metal container are extremely large and heavy, with a diameter of about 2.5 m, a height of about 6 m, and a weight of about 100 t.

  Generally, in a radioactive material storage facility, a cask is mounted on a storage platform, and is stored by fixing the platform to a predetermined position on the floor of a storage place provided in the facility. In addition, the casks are transported and stored in a radioactive material storage facility with the casks mounted on the gantry, and the casks mounted on the gantry are lifted and transported by a transfer device (hereinafter referred to as an air pallet) during the transfer. It is tied to the floor with bolts.

  Patent Documents 1 to 3 are known as conventional structures of a gantry used for such a cask. Further, although it is not a cask, there is Patent Document 4 as a fall prevention structure for precision instruments and the like.

JP 2001-228286 A JP 2003-255079 A JP 2007-64681 A JP-A-6-33583

  For example, suppose a huge earthquake occurred in an area where a radioactive material storage facility for storing casks was built. In that case, the cask causes vibrations such as vibrations in the vertical and horizontal directions or in the rotational direction (hereinafter referred to as rocking vibrations).

  That is, during vibration due to a huge earthquake, friction between the support leg installed on the gantry and the ground contact surface causes rotational vibration centering on the center of gravity of the heavy object and the point of action of the inertial force and the contact surface.

  Moreover, when moving a heavy article like a cask safely, the air pallet mentioned above is used. This air pallet can lift a heavy object by supplying air to a donut truss back and inflating the truss back. An air pallet is suitable for moving heavy objects because a heavy object can be moved with a slight force in a lifted state.

  However, even with an air pallet, if the supply of power is stopped due to a huge earthquake as described above, the supply of air cannot be performed. For this reason, the cask is placed directly on the ground, and the possibility of falling due to rocking vibration increases.

  On the other hand, Patent Document 1 is configured to reduce vibration caused by an earthquake by interposing a sliding pad with good sliding property between the floor surface and the cask to prevent the cask from overturning. However, in Patent Document 1, a damper is installed between the casks to prevent the cask from slipping excessively, and the structure is not suitable for transferring the cask.

  Moreover, in patent document 2, it becomes the structure which relieve | moderates the vibration by an earthquake by the combination of a slide plate and a thin plate as a fall prevention of a cask. However, Patent Document 2 is not a structure corresponding to the cask transfer.

  In Patent Document 3, support legs are provided at the four corners of a gantry on which a cask is mounted, and the gantry is directly fixed to the floor surface with fixing bolts that pass through the support legs and reach the floor surface. However, Patent Document 3 does not consider rocking vibration during cask transfer.

  Further, in Patent Document 4, although the cask is not prevented from falling, as a vibration isolator such as a precision instrument, a sliding type vibration isolating mechanism and a rolling type vibration isolating mechanism are opposed to each other diagonally.

  Thus, in each patent document, the fall of the cask or precision instrument by a huge earthquake is prevented by combining favorable slipperiness and a large frictional resistance.

  However, the earthquake countermeasures described in each patent document have a structure that assumes storage, and do not consider rocking vibration during transfer.

  Therefore, the object of the present invention is to fall over heavy objects such as casks that are stored and transported so that they can avoid overturning due to vibrations such as earthquakes without major structural changes of the entire gantry. It is to provide a prevention stand.

  In order to solve the above-described problems, the present invention provides a frame on which a radioactive substance storage container is mounted, support legs provided at the four corners of the bottom surface of the frame, and the support legs formed from the bottom surface of the frame to the floor surface. A high friction member having a ground contact surface with the floor surface that is higher in friction coefficient than the ground contact surface of the support leg on the bottom surface of the gantry directly below the radioactive substance storage container. It is provided.

  According to the present invention, it is possible to provide a heavy load overturn prevention stand that can avoid overturn of a heavy load against vibration such as an earthquake without making a large structural change of the whole stand for a heavy load such as a cask. Can do.

It is a perspective view of a cask and a mount concerning Example 1 of the present invention. It is a top view of the mount frame concerning Example 1 of the present invention. It is a bottom view of the mount frame concerning Example 1 of the present invention. It is a bottom view of the mount frame concerning Example 2 of the present invention. It is a side view of a cask and a gantry concerning Example 3 of the present invention. It is a side view of the cask and mount frame concerning Example 4 of this invention. It is a side view of the cask and mount frame concerning Example 5 of this invention. It is a side view of the cask and mount frame concerning Example 6 of this invention. It is a side view of a cask and a gantry concerning Example 7 of the present invention. It is a side view of the cask and mount frame concerning Example 8 of this invention.

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

  FIG. 1 is a perspective view of a cask and a gantry according to an embodiment of the present invention.

  In FIG. 1, the gantry 1 has a gantry base portion 3 on which a cask 2 is mounted, and fixing support legs 4 provided at the lower portion of the gantry base portion 3 are attached to four corners. By this support leg 4, a space 6 is formed on the upper surface of the gantry base 3 between the mounting portion 3 a where the cask 2 is mounted and the floor 5 such as a storage place of the cask 2.

  A pressing bolt 7 is attached to the peripheral portion 3b of the mounting portion 3a. The gantry 1 is fixed to the floor surface 5 (or the ground) of the radioactive substance storage facility while pressing the peripheral portion 3b in the direction of the floor surface 5 by the pressing bolts 7. Support leg mounting bolts 8 are attached to the peripheral portion 3b. Further, a fixture 9 for fixing the cask 2 to the gantry 1 is attached to the peripheral portion 3b.

  As shown in the figure, the air pallet 10 is inserted into the space 6 as indicated by an arrow, and is used when the cask 2 is moved together with the gantry 1.

  FIG. 2 is a plan view of the gantry according to the embodiment of the present invention.

  FIG. 3 is a bottom view of the gantry according to the embodiment of the present invention.

  In FIG. 2, this figure is the figure which looked at the cask 2 and the mount 1 from the upper surface, and showed the center point O of the cask 2. FIG. Since the same numbers as those in FIG. 1 are the same, the description thereof is omitted.

  3, this figure is the figure which looked at the mount 1 from the floor 5 side, and attaches the high friction member 11 to the mount 2 facing the gravity center position O point of the cask 2 shown in FIG. The support legs 4 at the four corners of the gantry 2 are low friction members. Since the same numbers as those in FIG. 1 are the same as in FIG. 2, the description thereof is omitted.

  As described above, in this embodiment, the high friction member 11 that contacts the floor surface 5 is attached to the center portion of the gantry 1 located directly below the cask 2, and the support legs 4 at the four corners are low friction members. Therefore, at the time of a huge earthquake, the contact point between the high friction coefficient member 11 and the floor surface 5 becomes the rotation center of the cask. At that time, the rotation moment due to the inertial force acting on the center of gravity position O of the cask is canceled by the support leg 4, and the rocking vibration is reduced, so that the cask can be prevented from falling.

  The material of the high friction member 11 may be a rubber material or a resin material. Alternatively, these materials may be used to form a high friction surface by roughing the contact surface with the floor surface.

  By the way, in the present embodiment, the bottom surface of the gantry 1 has been described with a combination of four corner (end) support legs and a central high friction member, but the present invention is not limited to this embodiment. For example, the same support legs as the support legs at the four corners may be attached to the center, and the coefficient of friction of the support legs at the center may be larger than the support legs at the four corners.

  FIG. 4 is a bottom view of the gantry according to the second embodiment of the present invention.

  In the present embodiment, the cask 2 and the gantry 1 described in the first embodiment are considered in consideration of a case where a load is applied in the arrow direction (excitation direction).

  In the description of this embodiment, the two support legs in the vibration direction are referred to as the front support legs 4a, and the two support legs on the opposite side are referred to as the rear support legs 4b.

  In FIG. 4, for example, when transporting the gantry 1 on which the cask 2 is mounted by truck, the rear support leg is taken into consideration when a load is applied in the arrow direction (vibration direction) when the truck is started or suddenly braked. 4b is a high friction member.

  As a result, the front support leg 4a in the vibration direction tries to slide, but the rear support leg 4b acts to prevent the slip, and the high friction member 11 can also suppress the rotational moment.

  As described above, according to the present embodiment, since the moment in the vibration direction and the rotation direction with respect to the cask can be prevented, the cask can be prevented from overturning.

  FIG. 5 is a side view of the cask and the gantry according to the third embodiment of the present invention.

  In FIG. 5, a cask 2 is mounted on the top of the gantry 1. A high friction member 11 is attached to a surface directly below the cask 2 and facing the floor surface 5 of the gantry 1. In the gantry 1 of this embodiment, a hemispherical member 12 is attached to the front support leg 4a. The hemispherical member 12 is in contact with the floor surface 5 in a low friction state.

  As described above, according to the present embodiment, the friction between the front support leg 4a and the floor surface is reduced by the hemispherical member 12, so that the rocking vibration can be prevented by promoting the sliding behavior in the excitation direction.

  FIG. 6 is a side view of the cask and the gantry according to the fourth embodiment of the present invention.

  In FIG. 6, a cask 2 is mounted on the top of the gantry 1. A high friction member 11 is attached to a surface directly below the cask 2 and facing the floor surface 5 of the gantry 1. In the gantry 1 of this embodiment, casters 13 are attached to the front support legs 4a. The hemispherical member 13 is in contact with the floor surface 5 in a low friction state.

  Thus, according to the present embodiment, since the friction between the front support leg 4a and the floor surface is reduced by the caster 13, the rocking vibration can be prevented by promoting the sliding behavior in the excitation direction.

  FIG. 7 is a side view of the cask and the gantry according to the fifth embodiment of the present invention.

  In FIG. 7, a cask 2 is mounted on the top of the gantry 1. A high friction member 11 is attached to a surface directly below the cask 2 and facing the floor surface 5 of the gantry 1. In the gantry 1 of this embodiment, a rubber member 14 as another member that is a high friction member is attached to the rear support leg 4a. The rubber material 14 is in contact with the floor surface 5 in a high friction state.

  As described above, according to the present embodiment, the friction between the rear support leg 4b and the floor surface 5 is increased by the rubber material 14, so that the rocking vibration can be prevented by promoting the sliding behavior in the excitation direction.

  FIG. 8 is a side view of the cask and the gantry according to the sixth embodiment of the present invention.

  In FIG. 8, a cask 2 is mounted on the top of the gantry 1. A high friction member 11 is attached to a surface directly below the cask 2 and facing the floor surface 5 of the gantry 1. In the gantry 1 of the present embodiment, a separate wood 15 as a high friction member is attached to the rear support leg 4a. The wood 15 is in contact with the floor surface 5 in a high friction state.

  As described above, according to the present embodiment, the friction between the rear support leg 4b and the floor surface 5 is increased by the wood 15, so that the rocking vibration can be prevented by promoting the sliding behavior in the excitation direction.

  FIG. 9 is a side view of the cask and the gantry according to the seventh embodiment of the present invention.

  In FIG. 9, a cask 2 is mounted on the top of the gantry 1. A high friction member 11 is attached to a surface directly below the cask 2 and facing the floor surface 5 of the gantry 1. In the gantry 1 of the present embodiment, another concavo-convex member 16 (in the present embodiment, a plurality of linear concavo-convex portions) is attached to the rear support leg 4a. The uneven member 16 is in contact with the floor surface 5 in a high friction state.

  Thus, according to the present embodiment, since the friction between the rear support leg 4b and the floor surface 5 is increased by the concavo-convex member 16, the rocking vibration can be prevented by promoting the sliding behavior in the excitation direction.

  FIG. 10 is a side view of the cask and the gantry according to the seventh embodiment of the present invention.

  In FIG. 10, a cask 2 is mounted on the top of the gantry 1. A high friction member 11 is attached to a surface directly below the cask 2 and facing the floor surface 5 of the gantry 1. In the gantry 1 of the present embodiment, another concavo-convex member 17 (in the present embodiment, provided with a plurality of columnar concavo-convex portions) which is a high friction member is attached to the rear support leg 4a. The uneven member 17 is in contact with the floor surface 5 in a high friction state.

  Thus, according to the present embodiment, since the friction between the rear support leg 4b and the floor surface 5 is increased by the concavo-convex member 17, the rocking vibration can be prevented by promoting the sliding behavior in the excitation direction.

  Further, by attaching a member made of a material having a larger coefficient of friction than the material of the support leg to the bottom surface of the rear support leg, it is possible to obtain a larger frictional force than the material of the support leg.

  Further, by attaching a member having a rough shape to the bottom surface of the rear support leg, a larger frictional force than the shape of the support leg can be obtained.

  In order to obtain high friction, a method of fitting a rubber material to a support leg is conceivable. However, with this method, it is possible to reduce the work without requiring a tool for the mounting work.

  As described above, according to the heavy fall prevention stand of the present invention, the center of rocking vibration is shifted from the front support leg to the rear support leg by installing a device having a different coefficient of friction with the ground contact surface for each support leg. Let In the case of unidirectional excitation, the front support legs are arranged at the front end of the gantry with respect to the excitation direction, and the rear support legs are arranged at the rear end of the gantry with respect to the excitation direction. In the case of multi-directional or alternating vibration, the front support leg is arranged at the front end of the gantry and the rear support leg is arranged at the center of the gantry with respect to the oscillating direction. At this time, the rocking vibration can be reduced by offsetting the rotational moment due to the inertial force acting on the position of the center of gravity of the heavy object and the rotational moment due to the normal force of the front support leg. The heavy fall prevention stand of the present invention utilizes the above-described effects.

1 ... mount,
2 ... cask,
3 ... the base of the base,
3a ... mounted part,
3b ... peripheral area,
4 ... support legs,
4a ... Front support leg,
4b ... Rear support legs,
5 ... Floor,
6 ... space,
7 ... Pressing bolt,
8 ... Support leg mounting bolts,
9 ... Fixing tool,
10 ... Air pallet,
11 ... high friction member,
12 ... Hemispherical member,
13 ... Caster,
14 ... rubber material,
15 ... wood,
16, 17 ... Uneven member.

Claims (7)

A frame on which the radioactive substance storage container is mounted; support legs provided at the four corners of the bottom surface of the frame; and a space of a predetermined interval formed by the support legs from the bottom surface of the frame to the floor surface;
Overturning a heavy object, characterized in that a high friction member having a ground contact surface with the floor surface having a higher friction coefficient than the ground contact surface of the support leg is provided on the bottom surface of the mount immediately below the radioactive substance storage container. Prevention stand. In the heavy load fall prevention stand according to claim 1,
The support legs are provided at the four corners of the bottom surface of the gantry,
The support legs are a front support leg and a rear support leg in a direction of vibration with respect to the gantry, and the coefficient of friction of the rear support leg is higher than the coefficient of friction of the front support leg. A stand to prevent objects from falling. In the heavy load fall prevention stand according to claim 2,
The heavy support fall prevention pedestal, wherein the front support leg includes a spherical body for sliding the heavy load and the pedestal with respect to a ground contact surface. In the heavy load fall prevention stand according to claim 2,
The front support leg has a caster for sliding the heavy object and the gantry with respect to a grounding surface, and the heavy article falls prevention gantry. In the heavy load fall prevention stand according to claim 2,
The above-mentioned rear support leg is made of a material having a friction coefficient higher than that of steel made of rubber, wood, or the like with respect to the ground contact surface. In the heavy load fall prevention stand according to claim 2,
The rear support leg has a heavy fall prevention stand characterized by having a rough surface due to a slit, a protrusion or the like with respect to a ground contact surface. In the fall prevention stand of the heavy article in any one of Claims 1 thru | or 6,
A heavy load fall prevention stand, wherein support legs are disposed at an end portion and a center portion of the bottom surface of the stand, and the support legs of the center portion have a larger coefficient of friction than the support legs of the end portion.

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