JPH0135315B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radioactive waste processing apparatus, and more particularly to a radioactive waste processing apparatus suitable for improving pellet filling efficiency in a pellet storage.

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. Therefore, it is required to fill the pellet storage with as many pellets as possible, that is, to improve pellet filling efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to improve the filling efficiency and to fill a pellet storage with pellets without damaging the pellets by means of a simple structure without a driving part.

The present invention provides a radioactive waste processing apparatus comprising means for turning radioactive liquid waste into powder, means for turning the powder into pellets, and a pellet storage for filling and storing the pellets from above. A spiral chute with an open top that supplies pellets into the pellet storage from above is provided along the wall inside the pellet storage with the number of turns of the spiral being one or less, and the height of the inner wall of the chute is set to the height of the outer wall of the chute. The above objective is achieved by making the temperature lower than the current value.

An outline of a radioactive waste processing apparatus which is a preferred embodiment of the present invention 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. Two input hoppers 22A and 22B are provided through the upper floor 16. Input hopper 22A and 2
The lower end of 2B projects into the space 20 within the inner container 19. The upper end is the input hopper 22A and 22B
Input chute 23A and 23B, which are connected to each other, are installed in space 20. FIG. 4 shows the three-dimensional structure of the charging hopper 22A and charging chute 23A, which are the pellet filling device 21A. The pellet filling device 21B, which is composed of a charging hopper 22B and a charging chute 23B, also has the same structure as the pellet filling device 21A. Input chute 23
A and 23B are configured in a spiral shape with an inclination angle θ. The tilt angle θ in this example is 32 degrees. When viewed from above the inner container 19, the input chute 23A and 23B are arranged point-symmetrically with respect to the center C of the inner container 19, as shown in FIG. 5, and have inclined surfaces in the same turning direction. have. Point A indicates the position of the input hopper 22A, and point B indicates the position of the input hopper 22B. FIG. 6 shows the cross-sectional shape of the input chute 23A. The input chute 23A is composed of a bottom portion 24, an outer wall portion 25, and an inner wall portion 26, and is open at the top.
If it is possible to prevent the pellets from falling on the way, the inner wall portion 26 may not be provided. The bottom portion 24 is inclined inwardly at an inclination angle α. The inner wall portion 26 is lower than the outer wall portion 25. 51 is a pellet of radioactive waste. The bottom of the input chute is supported by a plurality of support members 27. FIG. 7 shows the cross-sectional shape of another embodiment of the charging chute. This input chute 52 has a curved bottom surface, and the outside is higher than the inside.

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 and filling device 39 is located on the rail 38. An outline of the pellet removal and filling device 39 will be explained based on FIG. 8. mobile house 40
is installed on the rail 38. Pellet suction section 41, cyclones 44 and 48 and blower 4
9 is installed in the mobile house 40. The pellet suction section 41 has a retractable suction tube 42 inserted into the space 20 of the inner container 19. A flexible tube (not shown) is attached to the tip of the suction tube 42. A pipe 43 connected to the pellet suction section 41 is attached to the inlet nozzle 45 of the cyclone 44. A net 47 that is cylindrical and narrows at the bottom.
is suspended within the cyclone 44 as shown in FIG. An outlet nozzle 46 is provided at the upper end of cyclone 44. The piping 50 is connected to the cyclone 44
and 48 and the blower 49 are sequentially connected.

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 demineralizers provided in the water supply system and the furnace purification system is collected in the form of a slurry in a granular resin slurry tank 85. Further, 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 51 is manufactured by patent application No. 53-88657.
The pellets are moved to the input hopper 22A by a pellet transfer machine 14 having a conveyor as described in the above specification, and are supplied into the input hopper 22A. Fifth
As shown in the figure, the pellets 51 are placed in the input chute 2.
3A in the direction of arrow 52 to the bottom of the inner container 19. When the inclination angle θ of the input chute 23A is set to 28 degrees, the pellets 51 are
Start sliding inside. Therefore, the tilt angle θ must be 28 degrees or more. When θ<28 degrees, the pellet 51 does not slip. When the pellets 51 slide down inside the input chute 23, they are pushed against the outer wall 2 by centrifugal force.
It descends while being pressed by 5. The pellets 51 that have descended are accumulated on the bottom surface 53 of the inner container 19, as shown at 54 in FIG. pellet 51
The apex angle β of the mountain 54, that is, the angle of repose is 48 degrees. However, in the present invention, as shown in FIG. 14, the angle δ formed between the slope 55 of the mountain 54 and the horizontal line 56 will be referred to as the angle of repose. In this example, the angle of repose δ is 66 degrees. By the way, the size of pellet 51 is 27 mm in length, 18 mm in width, and 10 mm in thickness.
mm. When the top of the mountain 54 reaches the height of the lower end of the input chute 23A, the top of the mountain 54 prevents the pellets 51 from falling onto an extension of the input chute 23A. Bottom 2 of input chute 23A
4 is inclined inward at an inclination angle α, and the inner wall portion 26 is lower than the outer wall portion 25, so after colliding with the top of the mountain 54, the pellet 51 slides inside the input chute 23A and falls outside the input chute 23A. It jumps out and falls inward on the slope 55 of the mountain 54 as shown by the arrow 57 in FIG. If the heights of the outer wall 25 and the inner wall 26 of the input chute 23A are the same, the pellets 51 will only accumulate in the input chute 23A from the bottom toward the top.
Some of the pellets 51 that have slipped toward the inside of the input chute 23A slide down the slope of the mountain 54 toward the outside of the input chute 23A, as shown by the arrow 60 in FIG. As the pellets 51 fall in this way, the position of the top 58 of the mountain 54 rises along the input chute 23A, and a ridge of the mountain 54 of the pellets 51 is formed as shown by the broken line 59 in FIG. . The state of accumulation of pellets 51 in the inner container 19 is monitored by a television camera (not shown) installed in the inner container 19. When it is confirmed by the television camera that a certain amount of pellets 51 have been accumulated in the inner container 19, the supply of pellets 51 by the pellet filling device 21A is stopped,
The input hopper 22A is sealed. Thereafter, the upper end of the input hopper 22B is opened, and the moved pellet transfer device 14 starts supplying pellets 51 to the input hopper 22B. Pellet 51 is
It slides through the input chute 23B and accumulates on the bottom surface 53 of the inner container 19 as described above. pellet 51
Since the pellets are charged into the inner container 19 through the charging chute 23A and 23B, the pellets 51 are not damaged during pellet filling.

By alternately connecting the pellet transfer device 14 to the input hoppers 22A and 22B, the pellets 51 are gradually accumulated in the inner container 19, and the ridge of the mountain 54A shown in FIG. 14 spirals along the input chute 23A. The ridge of the other mountain 54B rises spirally from point F (Fig. 5) to point B along the input chute 23B. . When the tops of the peaks 54A and 54B contact the lower ends of the input hoppers 22A and 22B, as shown in FIG. 14, the filling operation of the pellets 51 into the inner container 19 is completed. The ridges of the mountains 54A and 54B formed initially are buried under the pellets 51 supplied later. Pellet 51 produced from radioactive liquid waste generated over several years from a boiling water reactor plant
is intermittently supplied into the inner container 19. After filling of the pellets 51 into the inner container 19 is completed, the pellets 51 are filled into the inner container disposed in the sealed space adjacent to the sealed space 30.

FIGS. 3 and 14 show the accumulation state of the pellets 51 in the inner container 19 when the filling operation of the pellets 51 into the inner container 19 is completed. Third
Figures and Figure 14 are - cross sections of Figure 5 and XI
-XI cross sections are shown. 59A is the ridge of the peak 54A produced by the pellet filling device 21A, and 59B is the ridge of the peak 54B produced by the pellet filling device 21B. 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 described above are formed, and a correspondingly large number of pellets 51 can be filled into the inner container 19. That is, in this embodiment, it is possible to fill the inner container 19 with pellets located above the broken line 61 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 51, the filling efficiency of the pellets 51 in the inner container 19 is significantly improved. Even in this case, θ≧28 degrees must be satisfied. Furthermore, 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 51 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 and filling device 15 is
The pellets 51 are moved on the rails 38 onto the inner container 19 from which the pellets 51 are taken out (FIG. 8). As shown in FIG.
0 and connected to the inlet nozzle 45.
The plug 62 of the upper floor 16 shown in FIG. 14 is removed and the suction tube 42 is inserted into the recess 63 of the pellets accumulated in the space 20. When the blower 49 is driven, pellets 51 are sucked up from the inner container 19 and filled into a drum 63 located at the lower part of the cyclone 44. Since the pellets 51 are guided by the net 47 within the cyclone 44, they do not collide with the inner wall of the cyclone 44 and are not damaged.
The drum 63 filled with pellets 51 is conveyed by a conveyor as described in Japanese Patent Application No. 53-88657, and the drum 63 is filled with asphalt. The drum 63 is sealed after the asphalt is solidified. Since the radioactivity level of the pellets 51 is low and the amount of pellets that can be filled into the drum can 63 increases, the solidified radioactive waste
In other words, the amount of drums generated is significantly reduced.

When filling the pellets 51, storing the pellets 51, and taking out the pellets 51,
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 51 in the inner container 19 are managed.

Another embodiment of the charging chute of the pellet filling device is shown in FIG. Point A is the position where the input hopper exists. The vertical cross-sectional shape of the input chute 65 is the same as that shown in FIG. The input chute 65 descends from point A toward point G while drawing a spiral. While the input chute 23A rotates half a revolution, the input chute 65 rotates once.
By providing such an input chute 65, the same effect as in the above-mentioned embodiment can be achieved, and at the same time, there is no need to provide two pellet filling devices 21A and 21B as in the above-mentioned embodiment.
The inner container 19 can be filled with just one pellet filling device.
The efficiency of filling the pellets into the pellets can be significantly improved. There is no need to alternately connect the pellet transfer device 14 to two input hoppers. However, compared to the previous embodiment, the height of the inner container must be increased.

FIG. 16 shows another embodiment of the charging chute.
In the pellet filling device of this embodiment, two pellet filling devices are arranged, similar to the embodiment shown in FIG.
One of these pellet filling devices is provided with an input chute 23A. The input chute 66 of the other pellet filling device is pivoted in the opposite direction to the input chute 23B. In this embodiment, the same effects as in the embodiment shown in FIG. 5 can be obtained, but the pellet filling efficiency is lower than in the embodiment shown in FIG. Two or more pellet filling devices are installed in the inner container 1.
9, it is desirable to rotate each input chute in the same direction as shown in FIG.

The radioactive waste treatment device of the present invention comprises recycled waste liquid,
It is also possible to treat one type of radioactive liquid waste, such as granular ion exchange resin slurry and super-aid slurry, alone or as a mixture of the two types.

According to the present invention, the filling efficiency of radioactive waste pellets can be greatly improved and the radioactive waste pellets can be filled into a pellet storage without damaging the radioactive waste pellets by using a pellet filling device having a simple structure without a driving part.

[Brief explanation of drawings]

FIG. 1 is a schematic system diagram of a radioactive liquid waste treatment apparatus which is a preferred embodiment of the present invention, and FIG.
A perspective view of the pellet storage and the pellet retrieval/filling device shown in the figure, Fig. 3 is a sectional view taken from Fig. 5 in a state in which the pellet storage has been completely filled with pellets, and Fig. 4 is a perspective view of the pellet storage installed in the pellet storage. A detailed view of the pellet filling device, FIG. 5 is an explanatory diagram showing the arrangement of the input chute in the pellet storage, which is a view of the inside of the pellet storage from above;
FIG. 6 is a sectional view taken from FIG. 4, FIG. 7 is a longitudinal sectional view of another embodiment of the input chute, and FIG. 8 is an explanatory diagram showing a state in which pellets are being taken out from the pellet storage. Figure 9 is a detailed view of the cyclone installed in the pellet extracting device in Figure 8.
Fig. 0 is an explanatory diagram showing the state of accumulation of pellets in the pellet storage when pellet filling is started, and Fig. 11 is an explanatory diagram showing the state of accumulation of pellets in the pellet storage after time has elapsed from the state shown in Fig. 10. The explanatory diagram shown in Figure 12 is XII-XII of Figure 11.
Fig. 13 is a cross-sectional view taken from Fig. 12, and Fig. 14 is a cross-sectional view taken from Fig. 5 when the pellet storage is completely filled with pellets.
The sectional view, FIG. 15, and FIG. 16 are explanatory diagrams showing other embodiments of the input chute. 6... Centrifugal thin film dryer, 13... Granulator, 14
... Pellet transfer machine, 15 ... Pellet storage facility, 16 ... Upper floor, 17 ... Exterior wall, 18 ...
Lower floor surface, 19... Inner container, 21A, 21B...
Pellet filling device, 23A, 23B... Input chute, 24... Bottom, 25... Outer wall, 26...
Inner wall portion, 39... Pellet removal and filling device, 40
...Mobile house, 41...Pellet suction section, 42
...Suction tube, 51...Pellet.

Claims (1)

[Scope of Claims] 1. A radioactive waste processing device comprising means for turning radioactive liquid waste into powder, means for turning the powder into pellets, and a pellet storage for filling and storing the pellets from above. , a spiral chute with an open top for supplying the pellets from the upper part of the pellet storage into the pellet storage is provided along the wall surface of the pellet storage with the number of spiral turns being one or less, and the height of the inner wall of the chute is A radioactive waste processing apparatus characterized in that the height of the chute is lower than the height of the outer wall of the chute. 2. The radioactive waste treatment apparatus according to claim 1, wherein the inclination angle θ of the chute is within the range of 28 degrees≦θ≦(repose angle δ). 3. The radioactive waste processing apparatus according to claim 1 or 2, wherein a plurality of the spiral chute are inclined in the same turning direction and arranged point-symmetrically with respect to the central axis of the pellet storage.