JPH08129100A - Disposal method of radioactive waste - Google Patents

Abstract

PURPOSE: To reduce residual coverage onto a disposal equipment by crushing massive radioactive waste, mixing the crushed waste with a solidifying material and infecting the mixture into a solidifying container. CONSTITUTION: When incinerated ash in a storage container 1 is charged into an incinerated-ash hopper 4 and a valve 5 is opened, the inside of a cage type rotor for a crusher 6 is supplied with incinerated ash. Moistened massive incinerated ash is shocked by pin shields, in which adjacent rows in the rotor are rotated in the opposite directions mutually, and crushed. Incinerated ash, in which massive ash is crushed completely, is introduced into a screw feeder 7, and the inside of a kneading machine 8 is supplied with incinerated ash by driving the feeder 7. Incinerated ash fed into the kneading machine 8 is kneaded with previously charged cement paste by an agitator 13, the inside of a solidifying container 15 is fed with these mixtures through an outlet piping by opening a solenoid valve 14, an upper end is sealed with a cover, and the solidifying container 15 is carried into a solidifying-container storage region.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for solidifying radioactive waste, and more particularly to radioactive waste suitable for treating radioactive waste containing lumps in powder such as incinerated ash and granules. The present invention relates to a method for solidifying a material.

[0002]

2. Description of the Related Art Among radioactive wastes generated from radioactive material handling facilities such as nuclear power plants, incineration ash can be stably solidified by using cement as a solidifying material. development of"
(Industrial Technology Publishing, p69-70, 1983, Amanuma, Sakata). Also, glassy substances such as granules and earth and sand can be solidified by the same method.

[0003]

The incineration ash is usually stored in a drum-shaped storage container in a dry state. However, the incinerated ash may be stored in a damp state at a portion contacted with the side surface of the storage container and a bottom portion of the storage container when water is splashed to prevent scattering. The inventors
The moist part of the incineration ash adheres to the solidification treatment equipment, increasing the surface dose rate and increasing the exposure dose to workers during maintenance and inspection. If it is attempted to suppress the increase in radiation dose to workers, the work time per worker is shortened, and the number of workers engaged in maintenance and inspection is increased.

The inventors have further found that when moist incinerated ash is stored in the storage container, it adheres to the storage container and makes it difficult to discharge the incinerated ash from the storage container.

Further, the solidification of the incineration ash described above in the prior art with cement has been premised on that the particles of the incineration ash are fine. However, as a new finding, the inventors have
The incineration ash that actually occurs as radioactive waste may partly become lumpy, and when it is solidified after being injected into the solidification container together with cement paste (a kneaded product of cement and water),
It was found that the incinerated ash that became a lump may settle at the bottom of the solidification vessel. As a result, there is a physical problem that the strength of the solidified body is reduced compared to the case where the incinerated ash is uniformly dispersed in the solidified body, and the surface dose rate of the solidified body is locally increased and the radiation dose to workers is increased. It was found that there are problems specific to radioactive waste such as waste.

[0006] An object of the present invention is to provide a method for treating radioactive waste, which can reduce the amount attached to the apparatus for treating radioactive waste.

Another object of the present invention is to provide a method for treating radioactive waste which facilitates discharge of radioactive waste from a storage container.

Another object of the present invention is to provide a method for treating radioactive waste which can significantly improve the compressive strength of the solidified body.

Another object of the present invention is to provide a method for treating radioactive waste which can remarkably uniformize the radioactivity concentration distribution in the solidified body in the axial direction.

Another object of the present invention is to provide a method for treating radioactive waste which allows the solidified bodies to have substantially the same surface dose rate and can be easily handled.

Another object of the present invention is to provide a method for treating radioactive waste which can prevent the radioactive waste discharged from the storage container from scattering.

[0012]

The feature of the invention according to claim 1 for achieving the above object is to crush lumped radioactive waste discharged from a storage container and mix the crushed radioactive material with a solidifying material. Then, these mixtures are poured into a solidification container.

According to a second aspect of the present invention that achieves the above-mentioned other object, the storage container is vibrated to discharge the radioactive waste stored therein, and the discharged massive radioactive waste is discharged. To crush.

The feature of the invention according to claim 3 for achieving the above-mentioned other object is that the maximum particle size of radioactive waste is 20 by crushing.
mm or less.

In order to achieve the above other object, the feature of the invention according to claim 4 is that the maximum particle size of radioactive waste is 5 mm by crushing.
It is to do the following.

The feature of the invention according to claim 5 that achieves the above other object is that the maximum particle size of radioactive waste is 1 mm by crushing.
It is to do the following.

The feature of the invention according to claim 8 for achieving the above-mentioned other object is to select the crushed radioactive waste by a selecting means.

A ninth aspect of the present invention that achieves the above-mentioned other object is to discharge radioactive waste from a storage container by attaching radioactive waste scattering prevention means to the storage container.

[0019]

By crushing the massive radioactive waste discharged from the storage container, a part of the radioactive waste having a smaller particle size and a larger part of the radioactive waste are mixed. For this reason, dry radioactive waste adheres around some damp radioactive waste with a reduced particle size,
Wet radioactive waste is superficially dry. The amount attached to the radioactive waste treatment device is reduced, and the radiation dose to workers during maintenance and inspection of the radioactive waste treatment device is significantly reduced. The solidification of the lumpy radioactive waste after crushing increases the compressive strength of the obtained solidified body and makes the distribution of radioactivity concentration in the axial direction of the solidified body more uniform.

Since the radioactive waste that is crushed is discharged from the inside by vibrating the storage container, the radioactive waste attached to the storage container can also be easily discharged. Therefore, there is no radioactive waste remaining in the storage container after discharging the radioactive waste.

The maximum particle size of radioactive waste is reduced to 20 by crushing.
By making this radioactive waste into a solidified body of less than mm, the compressive strength of the solidified body is significantly improved. In a solidified body containing radioactive waste having a maximum particle size of more than 20 mm, stress concentration occurs in the radioactive waste having a maximum particle size of more than 20 mm, so that the compressive strength of the solidified body is lowered. However, when radioactive waste having a maximum particle size of 20 mm or less is solidified, stress concentration does not occur and the compressive strength of the solidified body is significantly improved. Further, the radioactive concentration distribution in the axial direction of the solidified body is made more uniform.

The maximum particle size of radioactive waste is 5 mm by crushing
By setting the following to the solidified form of this radioactive waste, the variation in the radioactivity concentration in the solidified body can be remarkably improved, and the radioactivity concentration distribution in the axial direction of the solidified body can be made extremely uniform. It is also possible to obtain the effect obtained by crushing the maximum particle size of radioactive waste to 20 mm or less.

The maximum particle size of radioactive waste is 1 mm by crushing
Below, by making this radioactive waste into a solidified body, the variation in the radioactive concentration in the solidified body is substantially eliminated, and the radioactive concentration distribution in the axial direction of the solidified body becomes uniform.

Since the crushed radioactive waste is selected by the selecting means, the radioactive waste having a particle size larger than the predetermined particle size is removed, and thus the plurality of solidified products obtained have a radioactive concentration distribution in the axial direction. Will be substantially the same. this is,
The surface dose rate of each solidified substance becomes substantially equal, and their handling becomes easy.

Since the radioactive waste is discharged from the storage container by attaching the radioactive waste scattering prevention means to the storage container, the discharged radioactive waste passes through the space surrounded by the radioactive waste scattering prevention means, and the surrounding area. It is possible to prevent radioactive waste from being scattered into the area.

[0026]

EXAMPLE 1 A method for treating radioactive waste, which is a preferred example of the present invention, will be described using the apparatus for solidifying radioactive waste shown in FIG.

In this embodiment, radioactive incineration ash generated from a BWR plant is solidified with a cement-based solidifying material. The radioactive incineration ash generated from the BWR plant is filled in a drum-shaped storage container 1 and stored in a storage facility on the premises of the BWR plant for a certain period of time.
The radioactive incineration ash is usually stored in the storage container 1 in a dry state. However, this incinerated ash may be stored in the storage container 1 in a state where the surface of the incinerated ash that has been accumulated to prevent scattering is splashed with water and a part of the incinerated ash is wet before storage.

The radioactive waste solidification processing apparatus of this embodiment is
A rotatable charging device 3, a crusher 6 and a kneader 8 are provided. The charging device 3 is installed near the incineration ash hopper 4. The incineration ash hopper 4 is connected to the crusher 6 via a valve 5. The outlet of the crusher 6 is connected to the screw feeder 7. The screw feeder 7 is connected to a kneader 8 having a stirrer 13. The solidifying material hopper 9 and the water tank 10 are connected to the kneading machine 8 via a valve 11 and a valve 12, respectively. The electromagnetic valve 14 is installed in the outlet pipe connected to the lower portion of the kneader 8.

The detailed structure of the crusher 6 is shown in FIG. This crusher 6 is a cage mill. A cage rotor 40 (cage) in which a large number of cylindrical pin shields 41 are concentrically arranged in four rows on the circumference of the disk is installed in the casing 39. The receiving container 43 is arranged below the basket rotor 40. The receiving container 43 is attached to the casing 39. The cage mill rotates the cage rotor 40,
It is an impact type crusher that crushes by utilizing the impact force. The pin shields 41 in the basket rotor 40 rotate in opposite directions in adjacent rows, as indicated by arrows in FIG.

When the incineration ash in the storage container 1 is solidified, the storage container 1 is transferred from the storage facility to the charging device 3 by the carrier device 2. After that, the storage container 1 mounted on the charging device 3 is fixed to the charging device 3, and the lid of the sealed upper end of the storage container 1 is opened. The charging device 3 is rotated in the direction of the arrow in FIG. 1 until the upper opening of the storage container 1 faces downward. The incinerated ash in the storage container 1 is put into the incinerated ash hopper 4. The incinerated ash is supplied to the inside of the cage rotor 40 of the crusher 6 by opening the valve 5. The incinerated ash that has become wet and clumped is crushed by the impact of the pin shield 41 in which adjacent rows rotate in opposite directions. The incinerated ash after the crushing of the lump-shaped portion is completed is discharged from the basket rotor 40 into the receiving container 43. This incinerated ash is introduced into the screw feeder 7 from the receiving container 43 of the crusher 6. The incineration ash is supplied into the kneading machine 8 by driving the screw feeder 7.

In advance, 195 kg of cement from the solidifying material hopper 9 and 105 kg of water from the water tank 10 were mixed with the kneader 8
It is thrown in. The charging into these kneading machines 8 is
This is done by opening valves 11 and 12. Cement and water are kneaded by the stirrer 13, and cement paste is formed in the kneader 8. The incinerated ash supplied into the kneader 8 is kneaded with the cement paste by the stirrer 13. The mixture obtained by kneading the incinerated ash and the cement paste is the electromagnetic valve 1
By opening 4, the gas is supplied through the outlet pipe into the solidification container (drum can) 15 located below the outlet pipe. The upper end of the solidification container 15 is sealed by a lid. The solidification container 15 is carried into the solidification container storage area.

Most of the incinerated ash stored in the storage container 1 is in a wet state, but most of it is in a dry state. The crushing of the incinerated ash by the crusher 6 mixes a part of the wet incinerated ash having a reduced particle size and most of the dried incinerated ash. Therefore, the dry incinerated ash adheres around the wet incinerated ash that has been crushed to have a smaller particle size, and the wet incinerated ash is in a surfacely dry state. This prevents the incineration ash from adhering to the passage (including the screw feeder 7) through which the incineration ash from the crusher 6 to the kneader 8 passes. Since the adhered amount of the incinerated ash on the crusher 6 and the screw feeder 7 is remarkably reduced, the exposure dose of the worker at the time of maintenance and inspection of those devices is remarkably reduced.

Further, by crushing the massive incineration ash, the contact surface area between the solidified material such as cement and the incineration ash after solidification can be increased, and the nuclide trapping performance of the radioactive waste in the solidified body can be improved.

The cage mill used in this embodiment has the following advantages as compared with commonly used rotary cutter mills, ball mills, hammer mills and the like. That is,
(1) Since radioactive materials are handled, the structure is very simple and there is almost no failure. (2) The installation area of the device is small from the viewpoint of equipment layout. (3) It is most suitable for crushing a medium lump (several centimeters) of incineration ash to a few millimeters. (4) The particle size of crushed incinerated ash can be adjusted according to the purpose. (5) There is no generation of ultrafine powder that causes the scattering of radioactive materials. (6) It is possible to process even crushed objects that are wet or that are prone to adhesion. (7) Suitable for crushing substances that are not so hard, such as incinerated ash.
(8) There is little noise in the environment and it can be crushed quietly.

Embodiment 2 A method for treating radioactive waste, which is another embodiment of the present invention, will be described using the apparatus shown in FIG.

Also in this embodiment, the radioactive incineration ash generated from the BWR plant and filled in the storage container 1 is used.
(Including lumpy incinerated ash) was treated as in Example 1,
It is filled in the storage container 1 and solidified. Massive incineration ash,
In addition to being caused by water being applied to the surface of the deposited incineration ash as described in Example 1, the incineration ash present at the bottom in the storage container 1 during a long storage period is due to the weight of the upper incineration ash. It is also caused by being compressed.

In this embodiment, by adjusting the driving conditions of the crusher 6, the maximum particle size of the massive incineration ash discharged from the crusher 6 is 50 mm or less, 20 mm or less, 5 mm or less, 1 mm or less, 0, respectively. Five types of crushing of less than 0.1 mm were performed separately. In these five cases, the incinerated ash containing the incinerated ash having the maximum particle size is supplied to the kneader 8 by the screw feeder 7 and mixed with the cement paste already existing in the kneader 8. Then, this mixture is supplied into the solidification container 15. In any case, the incineration ash supplied to the kneading machine 8 is 100 kg, the cement is 195 kg, and the water is 105 kg. In addition to these five cases, a case was also carried out in which the massive incineration ash contained in the storage container 1 was directly put into the kneading machine 8 without being crushed and mixed with the cement paste. Incineration ash mixed,
The weights of cement and water are the same as in the other five cases.

The mixture of the incinerated ash and the cement paste in each case was supplied into the solidification container 15, and then cured at room temperature for one month while the solidification container 15 was sealed. With respect to each solidified body obtained in the above 6 cases, the compressive strength of the solidified body and the distribution of the radioactivity concentration were measured.

The relationship between the crushed particle size of the incinerated ash and the compressive strength of the solidified body is shown in FIG. The compressive strength of the solidified body is significantly increased when the crushing treatment is performed on the incinerated ash (characterized by the solid line), compared with the case where the crushing treatment is not performed on the incinerated ash (characterized by the dotted line). The crushing of the incineration ash taken out from the storage container 1 increases the compressive strength of the solidified body containing the ash. As for the compressive strength of the solidified body, the maximum particle size of incinerated ash is 0.
1 mm or less, 1 mm or less, 5 mm or less, and 20 mm or less 4
There is little change in the case. However, when the maximum particle size of the incinerated ash is 50 mm or less, the compressive strength of the solidified body is sharply reduced. By making the incineration ash having the maximum particle size of 20 mm or less into a solidified body, the strength of the solidified body is remarkably improved. When the incineration ash has a certain particle size or more, stress concentration occurs in the incineration ash having the particle size, and the compressive strength of the solidified body is reduced. When the incineration ash having a maximum particle size of 20 mm or less is made into a solidified body, stress concentration does not occur and the compressive strength of the solidified body is remarkably improved.

The variation of the radioactivity concentration in the solidified body due to sedimentation during solidification of the lumpy substance was also examined. When the variation in the radioactivity concentration of the solidified product is large, the surface dose rate of the solidified product is locally high, so that the possible filling amount of radioactive waste per solidified product is limited.

Table 1 shows the distribution of the radioactivity concentration of the solidified body in the above 6 cases. K

[0042]

[Table 1]

The soot 1 is the incinerated ash taken out from the storage container 1 and solidified without crushing, and the cases 2 to 6 are the incinerated ash crushed by the crusher 6 and then solidified as described above. is there. The distribution of the radioactivity concentration of the solidified body was obtained by dividing the solidified body into three parts, the upper part, the middle part and the lower part, and sampling the cores from each part to measure the radioactivity concentration.

As shown in Table 1, when the crushed incinerated ash is not crushed, the variation in the radioactivity concentration inside the solidified body is extremely large. The smaller the maximum particle size of the incineration ash, the more uniform the axial radioactivity concentration distribution inside the solidified body.
In particular, when the maximum particle size of incinerated ash is 5 mm or less, the radioactivity concentration distribution becomes almost uniform in the axial direction. Therefore,
By crushing the massive incineration ash to reduce the maximum particle size of the incineration ash to 5 mm or less, the dispersion of the radioactivity concentration in the solidified body is remarkably improved. In particular, when the maximum particle size is 1 mm or less, the variation in radioactivity concentration within the solidified body is substantially eliminated.

The present inventors have examined the sedimentation phenomenon when the lumpy material is solidified. The results of this examination will be described below. The lumpy substance is a sphere having a radius r, its specific gravity is ρ, and gravitational acceleration is g. Let η be the viscosity of the solidifying material paste such as cement paste. The downward force exerted on the lumpy material by gravity is represented by 4πρr ³ g / 3. When the lumpy material moves downward at the velocity U, the resistance force that it receives upward is
It is represented by 6πηrU. The lumpy substance in the solidification container 15 is
The force of ((4πρr ³ g / 3) -6πηrU) is received downward. For example, when the radius r of the agglomerate becomes n times, the gravity becomes n ³ times. However, the upward resistance of the lumpy material is only n times. Therefore, as the particle size of the lumpy substance increases, the downward force acting on the lumpy substance increases, and the lumpy substance is more likely to settle in the lower portion of the solidification container 15. When there is a large difference in the particle size of the agglomerates present in the solidification material in the solidification container 15, the variation in the radioactivity concentration in the solidification body increases.

Since the difference in the particle size of the incinerated ash is reduced by crushing the massive incinerated ash as in this embodiment, the maximum size of the incinerated ash and the minimum size of the incinerated ash in the cement paste in the solidification container 15 are reduced. The difference in the downward force acting on the incinerated ash becomes smaller. Therefore, by crushing the massive incineration ash, the variation in the radioactivity concentration in the solidified body is reduced. Such an effect also occurs in the above-described first embodiment.

Particularly, by setting the maximum particle size of the incinerated ash to 20 mm or less, the radioactivity concentration distribution in the axial direction of the solidified body is made more uniform, and the compressive strength of the solidified body is remarkably improved. The compressive strength of the solidified body is substantially the same when the incinerated ash having the maximum particle size of 5 mm or less is used and when the incinerated ash having the maximum particle size of 20 mm or less is used. However, the radioactivity concentration distribution in the axial direction of the solidified body becomes substantially more uniform when the incineration ash having the maximum particle size of 5 mm or less is used.

The crushing of the incineration ash is also effective in controlling the flow rate of the mixture when the mixture of the incineration ash and the cement paste is poured into the solidification container 15. That is, when the radioactive incineration ash is injected into the solidification container 15, it is necessary to carefully control the injection amount of the mixture by the electromagnetic valve 14 so that the radioactive waste does not scatter or overflow from the solidification container 15. However, when the incineration ash having a large particle size is included, the lump of the incineration ash may be caught in the opening generated when the opening degree of the electromagnetic valve 14 is slightly widened (for example, about 1 to 10 mm) to cause blockage. is there. The incinerated ash in the form of lumps is crushed by the crusher 6 and the electromagnetic valve 1
It is desirable to crush to a size that does not affect the flow rate control by 4.

Although not shown in FIG. 1, a sorter may be arranged between the crusher 6 and the screw feeder 7. This sorter is equipped with a sieve (or a mesh screen) for sorting incinerated ash having a predetermined particle size (for example, 5 mm) or less. The incinerated ash crushed by the crusher 6 is supplied to the upper part of the sieve in the sorting machine. The incineration ash falls on the sieve placed diagonally toward the bottom of the sieve. At that time, the incinerated ash that has passed through the sieve has a maximum particle size not larger than a predetermined particle size and is supplied into the screw feeder 7. Incinerated ash having a particle size larger than the predetermined particle size cannot pass through the sieve and is accumulated in a predetermined area in the sorting machine. These incinerated ashes are returned to the crusher 6 and crushed again. By such a treatment, the incinerated ash supplied to the kneading machine 8 always has a size equal to or smaller than the predetermined particle size. For this reason, the radioactive concentration distributions in the axial direction of the respective solidified bodies produced are almost equal, and the surface dose rates of the respective solidified bodies are substantially equal. This facilitates handling of the solidified body.

The effects obtained in the first embodiment also occur in this embodiment.

Although the present embodiment is directed to the incineration ash, it is naturally applicable to radioactive wastes in which a part of granules, earth and sand, etc. may become lumpy.

Example 3 A method for treating radioactive waste, which is another example of the present invention,
This will be described using the radioactive waste solidification processing device shown in FIG.

First, the structure of the radioactive waste solidification processing apparatus will be described below. The same configurations as those in FIG. 1 are denoted by the same reference numerals. The description will focus on the parts different from the configuration of FIG.
The radioactive waste solidification treatment apparatus used in this example is a single unit that can solidify incineration ash, pellets obtained by compressing powder of concentrated waste liquid, and used ion exchange resin (waste resin). Equipment.

The hopper 20 and the valve 22 are the crusher 6
And the screw feeder 7. The pellet hopper 23 is connected to the hopper 20 via a valve 24. The exhaust device 21 is connected to the hopper 20.
The waste resin tank 25 has a centrifugal dehydrator 27 through a valve 26.
Connected to. The centrifugal dehydrator 27 is connected to the screw feeder 30 via a hopper 28 and a valve 29. The screw feeder 30 is connected to the kneader 8. An axially expandable expansion pipe 14 is provided at the upper end of the incineration ash hopper 4. The shaker 18 is installed near the position where the storage container 1 attached to the charging device 3 is turned upside down.

First, the solidification process of incinerated ash will be described. When solidifying the incineration ash, valves 24 and 26 are used.
Remains closed. It is assumed that the incinerated ash partially moistened in the same manner as in Example 1 is stored in the storage container 1. After the storage container 1 is attached to the dosing device 3, the dosing tube 14 is attached to the open end of the storage container 1. In this state, the charging device 3 is rotated in the direction of the arrow and the storage container 1 is turned upside down. The shaker 18 applies vibration to the inverted storage container 1. The incinerated ash in the storage container 1 is discharged from the storage container 1 by being subjected to the vibration force of the vibration exciter 18.
It reaches the inside of the incineration ash hopper 4 through the charging pipe 17. The wet incineration ash may adhere to the bottom surface and side surfaces of the storage container 1. By incinerating the storage container 1 as described above, the incinerated ash attached to the storage container 1 can be completely discharged to the outside of the storage container 1. The incineration ash led from the incineration ash hopper 4 to the crusher 6 is crushed in the same manner as in the above-mentioned embodiments. In this example, the incinerated ash was crushed so that the maximum particle size was 5 mm or less. The incinerated ash after crushing is supplied into the hopper 20. Here, in order to prevent the scattering and leakage of the finely pulverized incinerated ash, the exhaust device 21 exhausts air. By opening the valve 22, the incinerated ash is
It is guided into the screw feeder 7 and supplied into the kneader 8. In the kneading machine 8, 150 kg of cement and 1
00 kg of water is supplied and a cement paste is formed. 150 kg of incinerated ash and the above cement paste,
It is mixed by the rotation of the stirrer 13. This mixture is
The solidification container 15 is filled by opening the electromagnetic valve 14. The solidification container 15 filled with the above mixture is
After the lid is attached, the solidified container is loaded into the storage area. Next, the solidification treatment of the concentrated waste liquid into powder will be described. Although not shown, the radioactive concentrated waste liquid containing sodium sulfate as a main component is powdered by a centrifugal thin film dryer. The granulator compresses this powder to form pellets with a length of about 3 cm. This pellet is temporarily stored in the pellet hopper 23. The pellets are sent to the hopper 20 by opening the valve 24. Meanwhile, solidifying material hopper 9 to 150 kg
50 kg of water from the water tank 10 is charged in advance into the kneading machine 8 through the valve 11 and the valve 12. The rotation of the stirrer 13 creates the cement paste. By opening the valve 22 and driving the screw feeder 7, the pellets in the hopper 20 are supplied into the kneader 8 in which the cement paste is present. The amount of this pellet is 220 kg. After sufficiently stirring the cement paste and the pellets with the stirrer 13, the electromagnetic valve 14 is opened. The mixture of pellets and cement paste in the kneader 8 is poured into the solidification container 15.
The solidification container 15 filled with the mixture is loaded into the solidification container storage area after being sealed with a lid attached.

Finally, an example of solidifying the waste resin will be described. The waste resin containing water is sent from the waste resin tank 25 to the centrifugal dehydrator 27 by opening the valve 26. The centrifugal dehydrator 27 dehydrates the waste resin. here,
The waste resin having a water content of about 50% is stored in the hopper 28. On the other hand, the valves 11 and 12 are opened, and 120 kg of cement from the solidifying material hopper 9 and 50 kg of water from the water tank 10 are charged into the kneading machine 8. The cement paste is prepared in the kneader 8 by driving the stirrer 13. The waste resin in the hopper 28 is sent to the screw feeder 30 through the valve 29. The screw feeder 30 supplies the waste resin to the kneader 8. The waste resin supplied to the kneading machine 8 is 120 kg. The cement paste and the waste resin are sufficiently mixed in the kneader 8. The obtained mixture is solidified in a solidification container 15 by opening the electromagnetic valve 14.
Injected inside. The solidification container 15 is also loaded into the solidification container storage area after being sealed with the lid attached.

The concrete solidification method of the radioactive wastes of the incineration ash, the concentrated waste liquid pellets, and the waste resin using the single equipment in this embodiment has been described above. Hereinafter, the method for solidifying incinerated ash will be particularly described in detail.

In the solidification treatment of the incinerated ash of this example, the storage container 1 was vibrated and the massive incinerated ash was crushed. In order to confirm the effect of the vibration and the crushing, the inventors of the present invention "when the vibration and the crushing are not performed", "when only the vibration is performed",
We examined four cases, "when only crushing was performed" and "when vibration and crushing were performed". The results are shown in Table 2. The "adhesion to the storage container" in Table 2 means the adhesion of the incineration ash to the inner surface of the storage container 1 after the charging device 3 is turned upside down and the incineration ash is discharged. “Adhesion to solidification treatment device” in Table 2 means a passage (screw feeder 7 and hopper 20) from the crusher 6 to the kneader 8 through which the incinerated ash passes.
Including incineration ash).

[0059]

[Table 2]

"When vibration and crushing are not performed", when a part of the incineration ash stored in the storage container 1 is in a wet state, "adhesion to the storage container" and "solidification processing device" There was "adhesion to". However, as in this example, “when vibration and crushing are performed” is “adhesion to storage container”
Nor was there "adhesion to the solidification treatment device". By the way, as in Example 1, "when only crushing" is performed,
There was "adhesion to the storage container" but not "adhesion to the solidification processing device". In addition, "when only vibration is performed",
On the contrary, there was no “adhesion to the storage container”, but there was “adhesion to the solidification processing device”.

As described above, in this embodiment, since the amount of incinerated ash attached to the solidification treatment device is remarkably reduced, the exposure dose of the worker at the time of maintenance and inspection of the solidification treatment device is remarkably reduced as in the first embodiment. To be done. Further, in this embodiment, there is no incinerated ash remaining in the storage container 1 after discharging the incinerated ash, and the entire incinerated ash in the storage container 1 can be solidified.

In addition to the effects described above, in this embodiment, since vibration is performed before crushing, when the incinerated ash is discharged from the storage container 1, the massive incinerated ash is roughly crushed by the vibrator 18. Therefore, it is possible to obtain an effect that the crushing time of the crushed incinerated ash by the crusher 6 is shortened.

The crusher 6 used in this example was a cage mill type. Although this has been described in the first embodiment, it is convenient because it is possible to process a damp material or a material that easily causes adhesion as compared with other types of crushers. This is because the cage mill type has almost no blind spot area beyond the crushing range compared to other types of crushers.

The vibrator 18 used in this embodiment is of a type that uses mechanical impact. Exciters other than this type include those using low frequency or ultrasonic waves. Moreover, since it suffices to remove the radioactive waste attached to the storage container 1 as a result, a device for scraping the radioactive waste in the storage container may be used instead of the vibration exciter. Table 3 shows the comparison result of the adhered incineration ash removal rate and the method for these devices for removing the incineration ash in the storage container.

[0065]

[Table 3]

The mechanical vibration exciter is superior to other incinerator ash removing devices in terms of both the removal rate of incinerated ash attached to the storage container 1 and the cost. Similarly, a scraping device having a high removal rate of incinerated ash needs to be put in and taken out from the storage container, and the taking out and putting in operation must be performed in consideration of the operation of discharging the incinerated ash from the storage container 1. For example,
After the storage container 1 is turned upside down by the charging device 3 to release the incineration ash from the storage container 1, the charging device 3 is returned to the state before rotation, and the scraping device is inserted into the storage container 1 from above to store the storage container 1. It is necessary to scrape off the incineration ash adhering to the inner surface, take out the scraping device from the storage container, and rotate the storage container again.
Therefore, it takes a long time to treat the incineration ash in one storage container, and the cost required for the treatment per solidified product increases. Further, it is necessary to remove the incineration ash attached to the scraping part inserted in the storage container. This complicates the equipment and increases the cost.

Further, in this embodiment, when the incinerated ash is charged from the storage container 1 to the incinerated ash hopper 4, the incinerated ash is connected to the storage container 1 by the bellows-like charging pipe 17. Since it is supplied to the incineration ash hopper 4,
It is possible to prevent radioactive incineration ash from scattering around.

The effect obtained in the second embodiment is also produced in this embodiment.

The charging device 3 and the vibrator 18 in this embodiment
And the radioactive waste solidification treatment device using the crusher 6 etc.
Naturally, it can be applied to the solidification treatment of radioactive waste that is partially moistened such as granules and earth and sand.

Example 4 This example is a method of solidifying granules generated from a PWR plant with cement. FIG. 5 shows a radioactive waste solidification processing device used in the radioactive waste solidification processing method of the present embodiment. The same components as those of the radioactive waste solidification treatment device shown in FIG. 1 are designated by the same reference numerals. Parts different from the configuration of FIG. 1 will be described.

The suction device 33 is connected to the outlet 32 provided in the granule storage tank 31. The exhaust device 34 is connected to the suction device 33. Granule hopper 35 connected to crusher 6A via valve 35
Is connected to the suction device 33. The other exhaust device 38 is
It is connected to the kneading machine 8. Other configurations are the same as those in FIG.

First, the radioactive granules stored in the granule storage tank 31 are sucked up to the suction device 33 through the outlet 32. At that time, the suction device 33 is exhausted by the exhaust device 34. After that, the granules are sent to the granule hopper 35, and further to the crusher 6A via the valve 36. The granules are crushed by the crusher 6A. On the other hand, 200 kg of cement from the solidifying material tank 9 and 80 kg of water from the water tank 10 are supplied to the kneading machine 8 through the valves 11 and 12, respectively. These are sufficiently kneaded by the stirrer 13 to form cement paste. The crushed granules are supplied to the kneading machine 8 by the screw feeder 7. This supply amount is 120 kg. The granules are mixed with the cement paste in the kneader 8. At this time, the exhaust device 38 exhausts air to prevent the granules from scattering. Then, the mixture of the granules and the cement paste obtained by the kneading machine 8 is injected into the solidification container 15 by opening the electromagnetic valve 14.
The solidification container 15 is sealed with a lid.

A hammer mill was used as the crusher 6A. The outline of the structure of the hammer mill is shown in FIG. Hammer mill
It is a crusher of a type that crushes an object to be crushed by an impact of a hammer 46 attached to a rotor 45 on a disc. The granules supplied from the upper part of the casing 44 are crushed by hitting a hammer 46 that is swung outward when the rotor 45 rotates at high speed. In addition, this allows the granules to have a casing 44.
It is smashed on the inner wall surface of No. The crushed granules are sorted by the screen 47 attached to the casing 44, and only the sufficiently crushed granules are discharged from the hammer mill. This hammer mill has a much higher crushing capacity than other types of crushers. Although the incineration ash can be crushed, it can crush solid substances such as glassy substances such as granules, and is a very effective crusher in this embodiment. In addition, since only the crushed pieces that have been reliably crushed by the screen 47 attached to the casing 44 are discharged, it is possible to eliminate the risk that lumpy granules are discharged from the hammer mill. This is very effective in handling radioactive waste.

As another crushing method, it is effective to use a screw feeder having a crushing function for the screw feeder 7. A screw type crusher may be used instead of the screw feeder 7. In terms of equipment, they can perform the two functions of crushing and transferring with one device, so that the installation location can be reduced.

In the present embodiment, granules were used as the radioactive waste to be treated, but the solidification method of the present embodiment is used when solidifying radioactive waste containing lumpy substances such as incinerated ash and earth and sand. Can also be applied to.

[0076]

According to the first aspect of the present invention, by crushing the massive radioactive waste discharged from the storage container, the amount attached to the radioactive waste processing device is reduced, and the radioactive waste processing device is reduced. The radiation dose to workers during maintenance and inspection is significantly reduced. The solidification of the lumpy radioactive waste after crushing increases the compressive strength of the obtained solidified body and makes the distribution of radioactivity concentration in the axial direction of the solidified body more uniform.

According to the second aspect of the present invention, since the storage container is vibrated and the radioactive waste crushed is discharged from the inside thereof, the radioactive waste adhering to the storage container can also be easily discharged. This eliminates the radioactive waste remaining in the storage container after the radioactive waste is discharged.

According to the third aspect of the present invention, the maximum particle size of the radioactive waste is reduced to 20 mm or less by crushing and the radioactive waste is made into a solidified body, whereby the compressive strength of the solidified body is remarkably improved. Moreover, the radioactivity concentration distribution in the axial direction of the solidified body is made more uniform.

According to the invention described in claim 4, the maximum particle size of the radioactive waste is reduced to 5 mm or less by crushing, and by making this radioactive waste into a solidified body, the variation in the radioactivity concentration in the solidified body becomes remarkable. It is improved and the radioactivity concentration distribution in the axial direction of the solidified body can be remarkably made uniform. The compressive strength of the solidified body is significantly improved.

According to the invention of claim 5, the maximum particle size of the radioactive waste is reduced to 1 mm or less by crushing, and by making this radioactive waste into a solidified body, the variation of the radioactivity concentration in the solidified body is substantially reduced. , The radioactivity concentration distribution in the axial direction of the solidified body becomes uniform. According to the invention described in claim 8, since the crushed radioactive waste is sorted by the sorting means, the surface dose rates of the solidified bodies are substantially equal, and the handling thereof is facilitated.

According to the ninth aspect of the present invention, the radioactive waste is discharged from the storage container by mounting the radioactive waste scattering prevention means on the storage container. Therefore, the discharged radioactive waste is prevented from scattering the radioactive waste. It is possible to prevent the radioactive waste from scattering to the surroundings through the space surrounded by the means.

[Brief description of drawings]

FIG. 1 is a structural diagram of a radioactive substance solidification processing apparatus used in a method for solidifying a radioactive substance according to a preferred embodiment of the present invention.

FIG. 2 is a detailed structural diagram of the crusher of FIG.

FIG. 3 is an explanatory diagram showing the relationship between the maximum particle size of incinerated ash and the compressive strength of the solidified body in the second example of the present invention.

FIG. 4 is a structural diagram of another radioactive substance solidification processing apparatus used in the radioactive substance solidification processing method according to another embodiment of the present invention.

FIG. 5 is a structural diagram of another radioactive substance solidification processing apparatus used in the radioactive substance solidification processing method according to another embodiment of the present invention.

FIG. 6 is a detailed structural diagram of the crusher of FIG.

[Explanation of symbols]

1 ... Storage container, 3, 16 ... Input device, 4 ... Incinerated ash hopper, 6, 6A ... Crusher, 7 ... Screw feeder, 8 ...
Kneading machine, 9 ... Solidifying material hopper, 15 ... Solidifying container, 18 ...
Shaker.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshi Komori 7-2-1, Omika-cho, Hitachi-shi, Ibaraki Hitachi Energy Co., Ltd. (72) Inventor Toshiaki Matsuo 7-2, Omika-cho, Hitachi-shi, Ibaraki No. 1 Incorporated Hitachi, Ltd. Energy Research Laboratory (72) Inventor Tatsuo Izumida 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory

Claims (9)

[Claims] 1. A radioactive waste stored in a storage container is discharged from the storage container, the discharged massive radioactive waste is then crushed, and the crushed radioactive material is mixed with a solidifying material. A method for treating radioactive waste, which comprises injecting the mixture of 1. into a solidification container. 2. The storage container is vibrated to discharge the radioactive waste stored therein, and then the discharged massive radioactive waste is crushed, and the crushed radioactive material is used as a solidifying material. A method for treating radioactive waste, which comprises mixing and injecting these mixtures into a solidification container. 3. The method for treating radioactive waste according to claim 1, wherein the maximum particle size of the radioactive waste is 20 mm or less by the crushing. 4. The method for treating radioactive waste according to claim 1, wherein the maximum particle size of the radioactive waste is 5 mm or less by the crushing. 5. The method for treating radioactive waste according to claim 1, wherein the maximum particle size of the radioactive waste is 1 mm or less by the crushing. 6. The radioactive waste contains at least one of incineration ash, granules and earth and sand,
3, 4 or 5 radioactive waste treatment method. 7. The method for treating radioactive waste according to claim 1, 2, 3, 4, 5 or 6, wherein the crushing is performed using a cage mill. 8. The method for treating radioactive waste according to claim 1, wherein the crushed radioactive waste is sorted by a sorting means. 9. The method for treating radioactive waste according to claim 1, wherein the radioactive waste is discharged from the storage container by attaching a radioactive waste scattering prevention means to the storage container.