JPS6046396B2 - Structure of storage tank in underwater cutting equipment for radioactive metal waste - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a storage tank in an underwater cutting apparatus for radioactive metal waste.

Channel boxes used in nuclear reactors need to be replaced periodically, and used ones are discarded, but because such parts are radioactive, they are generally kept at a depth of 13 TrL due to radiation exposure concerns. The current situation is that the fuel is stored in a fuel pool that extends over 1,000 yen. By the way, this channel box A is provided with a first spacer and a spacer 2, and if it is stored in the fuel pool as it is, its storage space will be large. In recent years, securing storage space has become an important problem in the industry due to the increase in the number of discarded parts of this type.

For this reason, it is conceivable to cut these channel boxes A to make them more visible and to make effective use of the storage space.
Mechanical means such as pressing, shearing, and punching, or a combination of these, have been used. However, with such methods, the equipment is large and complex, with a large number of parts, which increases the frequency of maintenance, and requires a long time to prepare for operation, so it lacks the speed of work, and it is difficult for workers to perform the work. There was a risk that the amount of radiation exposure would increase.

Furthermore, it is necessary to install at least the cutting section of such a device underwater, which poses many problems, such as the need to increase the size of the cutting tank and to make the foundation of the installation location strong. For this reason, the applicant of the present patent has proposed storing at least the cutting portion of radioactive metal waste such as channel box A and a fusing torch in a container that is previously placed underwater, and determining the relative positions of the radioactive waste and the fusing torch. We proposed an underwater cutting device that melts the radioactive metal waste by moving it.

The present invention relates to the structure of a storage tank used in this underwater cutting device, and in the storage tank into which a channel box is fed and cut, the storage tank has a rectangular cylindrical cutting head and a lower end of the head. It consists of a cylindrical storage section that is removable from the cutting head and linearly connected to the cutting head, and a cylindrical dross collection section that is connected to the lower end of the storage section via an inclined section, and that has a space within the cutting head. A fusing tank is formed between these guides by providing an upper guide and a lower guide, each of which is constituted by guide members provided at two opposite corners, and a fixed fusing torch is provided in the fusing tank. The present invention is characterized in that a fixed fusing torch and a moving fusing torch are each connected to a plasma arc power supply device.

An object of the present invention is to speed up underwater cutting work and simplify maintenance and inspection work.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the structure of a storage tank in an underwater cutting apparatus for radioactive metal waste according to the present invention will be described below with reference to FIGS. 2 to 5.

FIG. 2 shows a case where the storage tank 11 is installed in the fuel pool P, and the storage tank 11 is composed of a cutting head a, a storage part b, and a dross recovery part c. are removably connected by a flange 12.

13 is a plasma arc power supply device.

FIGS. 3 and 4 show the configuration of a cutting head a suitable for cutting a channel box A by melting,
3 is a plan view, and FIG. 4 is a sectional view taken along line DD in FIG. 3. The cutting head a has a flange 12 provided at the end of a rectangular cylinder 14 with a square horizontal cross section, and an upper guide 15 and a lower guide 16 (hereinafter abbreviated as guides 15 and 16) are provided inside the flange 12. The space between them is formed as a fusing tank 17. Guides 15 and 16
are formed from guide members 15A, 15B and 16A, 16B provided at two corresponding corners of the rectangular cylinder 14, and an angle θ inclined inward is formed on the upper surface of the guide member 15. Also, an inclination angle β is provided.

Reference numeral 18 denotes a fixed fusing torch which is mounted in the fusing tank 17 by a mounting member 19 at two corresponding corners of the rectangular cylinder 14, preferably at the two corners where the guides 15 and 16 are provided. 18'' is located approximately 2wn outward from the line 11 connecting the inner end edges 15'' and 16'' of the guides 15 and 16.

Reference numeral 20 denotes a movable fusing torch, which is arranged in the fusing tank 17 and configured to move horizontally in the direction of arrow d-d'' by a drive mechanism 22 such as a hydraulic cylinder attached to the rectangular cylinder 14 by a mounting member 21. At the same time, the distance between the tip 2' of the crater and the channel box A is maintained at approximately 2T!Rln.

The storage part b is a rectangular cylinder 33 as shown in FIG.
2, and a dross collecting section c is fixed to the lower end thereof. The dross collecting section c further includes an inclined section C1 and a storage section C2 for the collection tray 34. An opening 35 is provided in the upper part of the inclined section C1, and a lid 36 that opens the opening 35 is connected to the arrow f by a pin 37. -f'' direction. This opening 35 is connected to the collection tray 34.
This is for vertically taking out the inside of the storage section C2. The storage tank 11 configured as described above is installed in the fuel pool P as shown in FIG.

First, the case where the channel box A is blown out in such a state will be explained.

First, the channel box A is positioned so that the gazette 1 and the spacer are facing upward as shown in FIG. .

Spacer 2 installed at the top of channel box A
When the movable welding torch 20 is actuated and cut immediately before the cut piece A'' passes the movable welding torch 20 (dotted line area in Figure 1), the cut piece A'' remains suspended by the gripping device, while the cut channel The box A falls slightly downward and stops when its lower end comes into contact with the upper part of the dross collecting section c. After that, the cut piece A'' is lifted up and moved to another predetermined position, and then the channel box A is The fixed fusing torch 18 is operated while the channel box A is lifted up again by the gripping device, and the channel boxes A are sequentially pulled up to perform fusing. At this time, since the angle β is provided on the lower surface of the guide 15, the material to be cut easily enters the guide 15. In this way, after one edge line of channel box A is cut, in order to cut the opposing edge line, channel box A is held at 1800 degrees by a gripping device (not shown).
The objective can be achieved by rotating and lowering it and activating the stationary fusing torch 18. Alternatively, if one more fixed fusing torch is provided on the opposite side of the fixed fusing torch 180, when cutting the first ridge line, this additional torch is activated to simultaneously cut two opposing ridge lines of the channel box. Can be cut. The fused channel box A becomes two members each having an L-shaped cross section. During such fusing, the position of the channel box A is maintained by the guides 15 and 16 provided above and below, so that smooth fusing is possible. By stacking and storing the two cut members in this way, the channel box A can be stored as a rectangular parallelepiped, and its volume reduction properties are dramatically improved.
Note that when radioactive metal waste is melted in the storage tank 11, gas containing dust is generated in the tank 11, cutting dross that falls into the collection tray 34, and solid matter floating in the water.

Dust is radioactive, and if it is released into the atmosphere as it is, it will cause the problem of radiation exposure. Therefore, if necessary, the upper part of the storage tank 11 may be covered with a hood, and the inside of the hood may be led to a suction line having a filter, so that the inside of the hood is always under negative pressure during the fusing operation. On the other hand, if necessary, solid matter floating in the water is removed from the outlet along with the water by a pump through an outlet provided at the bottom of the storage part b, filtered by a filter, and then returned to the upper part of the cutting head a. You may choose to do so.

In addition, since the dross falls and accumulates in the collection tray 34,
It can be collected by periodically opening the lid 36 and taking out the collection tray 34 in the vertical direction.

As described above, according to the present invention, the gazette 1 and the spacer portion 2 can be removed by first cutting and removing the gazette 1 and the spacer portion 2 at the dotted line area in FIG. 1 using the apparatus of the present invention using a moving fusing torch. The remaining channel box from which the gusset and spacer have been cut can then be supported by the upper and lower guides in the cutting head and cut in the fusing bath between these guides.

That is, the cutting device of the present invention alone can cut the gusset, spacer portion, and other portions, and no other cutting device is required. Further, in the present invention, there is no need for a support device for supporting the channel box other than the upper guide and the lower guide, and the channel box can be easily cut and reduced in volume with a simple operation. Moreover, by integrating the devices necessary for cutting the channel box only in the cutting head, the structure of the entire storage tank can be simplified and downsized.

Furthermore, the cutting head only needs to be centrally maintained and inspected, and the storage section and dross collection section do not require particularly frequent maintenance and inspection, so the frequency of maintenance and inspection can be reduced. .

Furthermore, since the dross collecting section is provided with an inclined section, the collection tray stored in the dross collecting section can be easily collected without being affected by the cutting head or the storing section. Of course, the present invention is not limited to these embodiments, and it is clear that various changes can be made without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the channel box, and FIGS. 2 to 5 show an embodiment of the storage tank in the underwater cutting apparatus for radioactively contaminated metal according to the present invention. An explanatory diagram when the tank is installed in a fuel pool, FIG. 3 is a plan view showing an example of a cutting head that constitutes a part of the storage tank, FIG. 4 is a sectional view taken along line DD in FIG. 3, and FIG. The figure shows a longitudinal cross-sectional view of the inclined portion c (7) that constitutes a part of the storage tank. DESCRIPTION OF SYMBOLS 1... Gazette, 2... Spacer, 11... Storage tank, 12... Flange, 13... Plasma arc power supply device, 15... Upper guide, 16... Lower guide, flap 15A , 15B, 16A, 16B... Guide member, 17... Fusing tank, 18... Fixed fusing torch, 19, 21... Mounting member, 20... Moving fusing torch, 22... Drive mechanism , 33... rectangular cylinder body, 27,
31... Guide, 34... Collection tray, 35...
Opening, 36... Lid, 37... Pin, A... Channel box, a... Cutting head, b... Storage section, c... Dross collection section, C,... Inclined part ,C.

Claims (1)

[Claims] 1. A storage tank into which a channel box is fed and cut, the storage tank having a rectangular cylindrical cutting head, a cylindrical storage part that is removable at the lower end of the head and linearly connected to the head; It consists of a cylindrical dross collecting part connected to the lower end of the storage part via an inclined part, and an upper guide and a lower guide are provided at intervals in the cutting head, and a fusing tank is formed between these guides. The guides are each configured by guide members provided at two opposing corners, and the fusing tank is provided with a fixed fusing torch and a movable fusing torch, and the fixed fusing torch and the movable fusing torch are respectively connected to a plasma arc power supply device. A structure of a storage tank in an underwater cutting device for radioactive metal waste, which is characterized by: