JPH0135318B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for removing radioactive waste in the form of pellets, and more particularly, to a device for removing radioactive waste in the form of pellets suitable for removing the radioactive waste pellets from a storage without damaging them. It is something.

Radioactive waste fluid generated from nuclear power plants such as boiling water reactors is pulverized by a centrifugal thin film dryer. This powder is formed into pellets and then filled into drums. A solidifying agent such as asphalt and plastic is injected into the drum. Since the surface dose rate of drums is regulated, in the radioactive waste disposal method described above, the amount of pellets filled in the drums is small, and a large number of drums containing radioactive waste are generated.

In order to reduce the number of drums filled with pellets and solidified, a radioactive waste disposal method as described in Japanese Patent Laid-Open No. 52-34200 has been considered. That is, the method involves temporarily storing the pellets to attenuate their radioactivity levels and then solidifying them. The structure of the pellet storage warehouse for storing pellets is based on patent application No. 53-88657.
A double-structure structure as described in the specification of the above patent has been proposed. The pellet storage is filled with pellets produced from radioactive liquid waste produced in boiling water reactors during several years of operation.

The radioactively attenuated pellets in the pellet storage are taken out from the pellet storage and then filled into drums. Asphalt is injected into the drum. When removing pellets from the pellet storage, it is required to remove most of the pellets from the pellet storage without damaging the pellets.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a device for removing pelletized radioactive waste with less risk of damage to the pelletized radioactive waste.

In order to achieve the above-mentioned object, the present invention provides a pellet-like radioactive waste retrieval device, which is configured by a plurality of cylindrical bodies being slidably attached in the axial direction, and a storage chamber filled with radioactive waste pellets. a first pellet suction pipe inserted into the storage from the upper part of the pellet suction pipe; a flexible second suction pipe attached to a cylindrical body that moves to the bottom of the first pellet suction pipe; and a second flexible suction pipe that moves the cylindrical body up and down. a first driving means; a second driving means for moving the tip of the second pellet suction tube in the direction of the wall of the pellet storage by moving the tip in the vertical direction;
It is characterized by comprising means for rotating the tip of the second pellet suction tube about the axis of the first pellet suction tube, and pellet suction means attached to the suction side of the first pellet suction tube. It is something to do.

A radioactive waste treatment device to which the present invention is applied,
This will be explained based on FIG.

The waste liquid receiving tank 1 is connected to a mixing tank 4 via a pump 2 and a concentrator 3. Granular resin slurry tank 85 and super-aid slurry tank 86
is communicated to the mixing tank 4 via the slurry transfer pump 7. The mixing tank 4 is a centrifugal thin film dryer 6
A pump 5 is provided in the middle of the connecting pipe. The centrifugal thin film dryer 6 is based on a patent application filed in 1983.
As described in the specification of No. 80997, the processing liquid is heated by heating the body to which the treatment liquid is supplied, the rotating shaft inserted into the body, the rotating blades attached to the rotating shaft, and the wall surface of the body. It consists of means. The lower part of the centrifugal thin film dryer 6 is a granulator 13.
connected to. The pellet transfer machine 14 is the granulator 1
3 and the pellet storage facility 15 are arranged to communicate with each other. 39 is a pellet take-out and filling device.

The detailed structure of the pellet storage facility 15 will be explained based on FIGS. 2 and 3. The pellet storage facility 15 is located underground in the radioactive waste processing building. An inner container 19 made of concrete is installed in a sealed space 30 below the upper floor surface 16 and surrounded by the outer wall 17 and the lower floor surface 18. By making the pellet storage a double structure consisting of an outer container consisting of an upper floor surface 16, an outer wall 17 and a lower floor surface 18, and an inner container 19, the contents can be accessed from the outside of the outer wall 17 and lower floor surface 18 underground. The risk of groundwater infiltrating into the vessel 19 can be reduced. The upper end of the inner container 19 is integrated with the upper floor surface 16. Pellet filling device 21A and 2 with input hopper 22
1B is arranged within the space 20 of the inner container 19.
Each input hopper 22 is provided through the upper floor surface 16. The three-dimensional structure of the pellet filling device 21A consisting of the charging hopper 22 and the charging chute 23 is shown in FIG. The pellet filling device 21B also
It has the same structure as the pellet filling device 21A. The input chute 23 is configured in a spiral shape with an inclination angle θ. The tilt angle θ in this example is 32 degrees. Input chute 2 of pellet filling devices 21A and 21B
3 shows the inner container 19 when viewed from above.
As shown in FIG. 5, the inner container 19 is arranged near the wall surface of the inner container 19 in a point symmetrical manner with respect to the center C of the inner container 19, and has an inclined surface in the same turning direction. Point A and point B are pellet filling devices 21A and 21
The positions of the input hopper 22 of B are shown respectively. FIG. 6 shows the cross-sectional shape of the input chute 23. The input chute 23 is located at the bottom 2
4. It is composed of an outer wall part 25 and an inner wall part 26, and the upper part is open. The bottom portion 24 is inclined inwardly at an inclination angle α. The inner wall portion 26 is the outer wall portion 2
Lower than 5. 69 is a radioactive waste pellet. The bottom of the input chute has a plurality of support members 2
Supported by 7.

The lining plate (not shown) is the inner container 1
It is installed over the entire inner surface of 9. A dry air supply pipe 28 is inserted into the space 20 at the bottom. A large number of jet ports 29 are provided in the dry air supply pipe 28 . Piping 34 communicates space 20 within inner container 19 with a radioactive gas processing device (not shown). A large number of leakage water collection pipes 31 are provided on the wall of the inner container 19, outside the lining plate and inside the outer wall 17. The leakage water collection pipe 31 is connected to the lower floor surface 1
It is connected to a leakage water detection device 32 arranged in a space 33 formed below 8. 35 is an atmospheric condition detector, and 36 and 37 are drain pipes.

A rail 38 is provided on the upper floor 16.
A pellet removal device 39, which is a preferred embodiment of the present invention, is located on the rail 38. The pellet removal device 39 will be explained based on FIGS. 7, 8 and 9. The mobile house 40 is connected to the rail 38
installed on top. A pellet suction unit 42 is installed within the mobile house 40. Pellet suction section 40
consists of cylindrical bodies 43, 44 and 45, flexible tube 52 and hoisting machines 49A, 49B and 55. The cylindrical body 44 is inserted into the cylindrical body 43, the cylindrical body 45 is inserted into the cylindrical body 44, and each cylindrical body is attached so as to be slidable in the axial direction. A support body 46 on which a bearing 47 is attached,
It is attached to the mobile house 40. A support plate 48 attached to the upper end of the cylindrical body 43 supports the bearing 4.
It is installed on 7. Hoisting machine 49A and 49B
is installed on the support plate 48. Ropes 50A and 50 wound on hoisting machines 49A and 49B
B is attached to a pair of protrusions 51A and 51B provided at the lower end of the cylindrical body 45. A flexible tube 52 is detachably attached to the lower end of the cylindrical body 45. As shown in FIG. 10, a suction port 53 having a hole 54 on the side surface is formed at the tip of the flexible tube 52. As shown in FIG. Projections 57 and 58
However, the lower end of the cylindrical body 45 and the flexible tube 5
It is provided at the tip of 2. The rope 56 attached to the protrusion 58 is connected to the support plate 4 via the protrusion 57.
8 is wound up by a winding machine 55 attached to the winding machine 55.

Cyclones 61 and 65 and blower 66
is installed inside the mobile house 40. A pipe 60 connected to the cylindrical body 43 of the pellet suction section 42 is
It is attached to the inlet nozzle 62 of the cyclone 61. A cylindrical mesh 64 that is narrower at the bottom is connected to the first
As shown in FIG. 1, it is suspended within a cyclone 61. An outlet nozzle 63 is provided at the upper end of the cyclone 61. Piping 67 sequentially communicates with cyclones 61 and 65 and blower 66.

The operation of this embodiment will be explained by taking as an example a method for treating radioactive liquid waste generated from a boiling water nuclear reactor. Radioactive liquid waste generated from boiling water nuclear reactors includes recycled waste liquid containing sodium sulfate as a main component, granular ion exchange resin slurry, and super-aid slurry. Regeneration waste liquid is generated by regeneration operations of granular ion exchange resins used in boiling water nuclear reactor plants. This recycled waste liquid is collected in the waste liquid receiving tank 1. After that, the recycled waste liquid is
It is concentrated in a concentrator 3 and sent to a mixing tank 4.
The used granular ion exchange resin filled in the demineralizer provided in the water supply system and the furnace purification system is collected in the form of slurry in a granular resin slurry tank 85. Furthermore, the used super-aid used in the condensate filter and equipment drain system is also collected in the form of slurry in the super-aid slurry tank 86. Granular ion exchange resin slurry and super-aid slurry are
The slurry is sent to the mixing tank 4 by driving the slurry transfer pump 7. The recycled waste liquid, granular ion exchange resin slurry, and super-aid slurry are stirred and mixed in the mixing tank 4.

These mixed liquids are supplied into the centrifugal thin film dryer 6. The mixed liquid is heated in the centrifugal thin film dryer 6 and turned into powder by the action of the rotating shaft and blades. i.e. sodium sulfate,
The granular ion exchange resin and super-aid are turned into powder. The powder is sent to a granulator 13 and formed into almond-shaped pellets. The steam generated in the centrifugal thin film dryer 6 has entrained particles removed in a decontamination tower 8, and then is cooled in a cooler 10 to become condensed water. The condensed water is temporarily stored in a tank 11 and pump 1
2 to the concentrator 3. The steam generated in the condenser 3 is condensed in the cooler 87, then guided into a condensate storage tank and reused as cooling water for a boiling water reactor plant.

The molded pellet 69 is manufactured by patent application No. 53-88657.
The pellets are fed into the input hopper 22 by a pellet transporter 14 having a conveyor as described in the above specification. As shown in FIG. 5, the pellets 69 are
It descends inside the input chute 23 in the direction of arrow 88 to the bottom surface of the inner container 19 while being pressed against the outer wall portion 25 by centrifugal force. Inclination angle θ of input chute 23
When the angle is set to 28 degrees, the pellets 69 begin to slide inside the input chute 23. Therefore, the tilt angle θ must be 28 degrees or more. Descended pellet 6
9 is the inner container 1 as shown by reference numeral 71 in FIG.
It accumulates on the bottom surface 70 of 9. The apex angle β of the mountain 71 of the pellet 69, that is, the angle of repose is 48 degrees.
However, in the present invention, as shown in FIG. 15, the angle δ formed between the slope 72 of the mountain 71 and the horizontal line 73 will be referred to as the angle of repose. In this example, the angle of repose δ
is 66 degrees. Incidentally, the pellet 69 has a length of 27 mm, a width of 18 mm, and a thickness of 10 mm. When the top of the mountain 71 reaches the height of the lower end of the input chute 23, the pellets 69 are prevented from falling onto the extension of the input chute 23 by the top of the mountain 71. The bottom part 24 of the input chute 23 is inclined inward at an inclination angle α, and the inner wall part 26 is inclined inwardly at an inclination angle α, and the inner wall part 26 is
After colliding with the top of the mountain 71, the pellet 69 slides inside the input chute 23, flies out of the input chute 23, and climbs the mountain inward as shown by the arrow 74 in FIG. 71 falls on the slope 72. Some of the pellets 69 that have slipped toward the inside of the input chute 23 slide down the slope of the mountain 71 toward the outside of the input chute 23, as shown by the arrow 75 in FIG. As the pellets 69 fall like this, the top 76 of the mountain 71
The position rises along the input chute 23, and a ridge 77 of a mountain 71 is formed. The state of accumulation of pellets 69 in the inner container 19 is monitored by a television camera (not shown) installed in the inner container 19. When a certain amount of pellets 69 have accumulated in the inner container 19, the supply of pellets 69 by the pellet filling device 21A is stopped. Thereafter, the pellets 6 are loaded into the inner container 19 by the pellet filling device 21B.
9 supply starts. The pellets 69 are filled into the inner container 1 by pellet filling devices 21A and 21B.
Since the pellets 69 are fed into the pellets 9, the pellets 69 are not damaged during pellet filling.

The pellets 69 are gradually accumulated in the inner container 19, and the ridge 77A of the mountain 71A shown in FIG. The ridge 77B of one mountain 71B spirals F along the input chute 23.
It rises from point (Fig. 5) toward point B. mountain 71
When the tops of A and 71B touch the lower end of the input hopper 22, as shown in FIG.
The filling operation of the pellets 69 into the inner container 9 is completed, and the filling operation into other inner containers is started. Pellets 69 produced from radioactive liquid waste generated over several years from a boiling water nuclear reactor plant are intermittently fed into the inner vessel 19.

FIGS. 3 and 15 show the accumulation state of the pellets 69 in the inner container 19 when the filling operation of the pellets 69 into the inner container 19 is completed. Third
The figure and FIG. 15 show the - section and - section of FIG. 5, respectively. If pellets are dropped into the inner container 19 from one input hopper without using the input chute, the pellets may be damaged, and moreover, a conical pile of pellets with an apex angle β will be formed in the inner container 19. Only. By using the charging chute of this embodiment, the ridges 77A and 77B as described above are formed, and a correspondingly large number of pellets 69 can be filled into the inner container 19. That is, in this embodiment, it is possible to fill the inner container 19 with the pellets 61 located above the broken line 78 in FIG. 3 using one pellet filling device. By improving pellet filling efficiency, wasted space within the inner container 19 is reduced and the pellet storage facility can be made more compact. Along with this, the radiation control area will also become narrower. By making the inclination angle θ of the charging chute smaller than the repose angle δ of the pellets 69, the filling efficiency of the pellets 69 in the inner container 19 is significantly improved. Even in this case, θ≧28 degrees must be satisfied. Also,
Since the pellet filling device does not have a driving part, there is no possibility of failure and no maintenance or inspection is required. This will lead to a reduction in the risk of radiation exposure for workers.

The pellets 69 are stored in the inner container 19 for more than ten years and are removed from the inner container 19 after the radioactivity level has decreased. The pellet removal device 39 is moved on the rail 38 onto the inner container 19 from which the pellets 69 are removed (FIG. 7). A pellet suction section 42 is attached to the mobile house 40 as shown in FIG. 8 and is connected to an inlet nozzle 62 by a piping 60. The plug 80 of the upper floor surface 16 shown in FIG. 15 is removed, and the cylindrical body 43,
A suction tube 81 consisting of 44 and 45 is inserted into the recess 79 of the pellets accumulated in the space 20. The flexible tube 52 is the lower end of the suction tube 81,
That is, it is not attached to the lower end of the cylindrical body 45. When the blower 66 is driven, the pellets 69 are sucked up from the inner container 19 through the suction tube 81.
A drum can 68 located below the cyclone 61 is filled. Pellet 69 is cyclone 61
Since it is guided into the inner net 64, it does not collide with the inner wall of the cyclone 61 and is not damaged. The drum 68 filled with pellets 69 is manufactured by patent application 1983-
The asphalt is transported by a conveyor and filled into the drum 68 as described in the 88657 specification. The drum 68 is sealed after the asphalt is solidified. Since the radioactivity level of the pellets 69 is low and the amount of pellets that can be filled into the drum 68 is increased, the amount of solidified radioactive waste, that is, the amount of drums generated, is significantly reduced.

When filling the pellets 69, storing the pellets 69, and taking out the pellets 69,
As shown in FIGS. 13, 14 and 15 of the specification of No. 53-88657, the dry air supply pipe 28
Dry air is supplied into the inner container 19 from the inside container 19, and the pellets 69 in the inner container 19 are managed.

As the pellets 69 in the inner container 19 are sucked out, the hoisting machines 49A and 49B are operated to loosen the ropes 50A and 50B, and the cylindrical body 45 is gradually lowered. FIG. 16 shows a state in which the cylindrical body 45 has reached the bottom surface of the inner container 19 while sucking the pellets 69. After that, the suction tube 81
is taken out from inside the inner container 19, and the flexible tube 5
2 is attached to the lower end of the cylindrical body 45. Suction tube 8
1 and flexible tube 52 are inserted into the inner container 19. By operating the hoisting machines 49A and 49B, the suction port 53 of the flexible tube 52 is connected to the inner container 19.
The cylindrical body 45 is lowered until it contacts the bottom surface of the cylindrical body 45.
By operating the hoist 55, the rope 56 is naturally loosened. When the suction port 53 contacts the bottom surface, the cylindrical body 45 is lowered a little, and the hoist 55 is operated to slightly lift the tip of the flexible tube 52. By such operation, the suction port 53
moves in a slightly outward direction from point P on the extension of the axis of the suction tube 81. When the blower 66 is driven in this state, the pellets 6 existing outside the point P
9 suction becomes possible. Further pellets 69 can be sucked by rotating the support plate 48 manually or electrically through 360 degrees. If it becomes impossible to suck the pellets 69 in this state, by lifting the tip of the flexible tube 52 again and lowering the cylindrical body 45 again, the pellets 69 can be sucked over a wider range. By operating the hoisting machines 49A, 49B and 55 and rotating the support plate 48 in this manner, even the pellets 69 present at the four corners of the bottom of the inner container 19 can be completely sucked in without damaging them. . Such operations are performed on the inner container 19.
It will be monitored by a television camera installed inside.

According to this embodiment, since the distance between the pellet and the tip of the suction part can be made substantially constant, the pellet can be taken out with less suction force. Therefore, with a simple structure, the pellets can be completely taken out from the storage without damaging the pellets. In addition, according to this embodiment, since the pellets are taken out by suction, the pellets can be taken out while maintaining the airtightness of the storage, and even if the pellets are damaged, radioactive materials can be removed from inside the storage. Waste powder does not fly out.

According to the present invention, the pellets can be taken out with a small suction force, so that the pellets can be taken out from the storage without being damaged.

[Brief explanation of drawings]

Fig. 1 is a schematic system diagram of a radioactive liquid waste processing apparatus to which a preferred embodiment of the present invention is applied, and Fig. 2 shows the pellet storage shown in Fig. 1 and the pellet extractor which is a preferred embodiment of the present invention. FIG. 3 is a perspective view of the device; FIG. 3 is a sectional view taken from FIG. 5 in a state in which pellets have been completely filled into the pellet storage; FIG. The figure shows the inside of the pellet storage as seen from above, and is an explanatory diagram showing the arrangement of the input chute in the pellet storage. Fig. 6 is a cross-sectional view of Fig. 4, and Fig. 7 shows the present invention shown in Fig. 2. 8 is an explanatory diagram showing a state in which the pellet suction section provided in a preferred embodiment of the invention is inserted into the pellet storage; FIG. 8 is a vertical sectional view of the pellet suction section shown in FIG. 7;
The figure is a cross-sectional view of Figure 8, Figure 10 is an enlarged view of Figure 9, Figure 11 is a detailed view of the cyclone installed in the pellet removal device of Figure 7, and Figure 12 is the start of pellet filling. FIG. 13 is an explanatory diagram showing the accumulation state of pellets in the pellet storage after time has passed from the state shown in FIG. 10, and FIG. 14 is an explanatory diagram showing the accumulation state of pellets in the pellet storage when Fig. 13 is a - arrow view, and Fig. 15 is a - arrow view of Fig. 5 in a state in which filling of pellets into the pellet storage is completed.
A cross-sectional view, FIG. 16 is an explanatory diagram showing the state of pellet suction by the suction tube, and FIG. 17 is an explanatory diagram showing the state of pellet suction using the flexible tube. 6... Centrifugal thin film dryer, 13... Granulator, 14
... Pellet transfer machine, 15 ... Pellet storage facility, 16 ... Upper floor surface, 19 ... Inner container, 21
A, 21B...Pellet filling device, 23...Charging chute, 39...Pellet removal device, 40...
Mobile house, 42... Pellet suction section, 43, 4
4, 45... Cylindrical body, 48... Support plate, 49A,
49B, 55...Hoisting machine, 50A, 50B, 56
... Rope, 52 ... Flexible pipe, 53 ...
Suction port.

Claims (1)

[Scope of Claims] 1. A first pellet suction device, which is configured by a plurality of cylindrical bodies attached so as to be slidable in the axial direction, and is inserted into the storage from the upper part of the storage filled with radioactive waste pellets. a flexible second suction tube attached to a cylindrical body that moves to the lowest part of the first pellet suction tube; a first driving means for raising and lowering the cylindrical body; and a tip of the second pellet suction tube. a second driving means for moving the distal end portion in the direction of the wall surface of the pellet storage by moving the distal end portion in the vertical direction; A device for taking out pellet-shaped radioactive waste, comprising: rotating means; and pellet suction means attached to the suction side of the first pellet suction tube.