JPH0778556B2 - Dewatering method for powdery radioactive waste - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dehydrating powdery radioactive waste such as ion exchange resin used for wastewater treatment of nuclear power plants.

[0002]

2. Description of the Related Art A granular radioactive waste such as waste ion exchange resin is put into an incinerator for incineration, but since it is used in water, it is in a slurry state containing a large amount of water, It is necessary to dehydrate before incineration to reduce the load on the incinerator. For this reason, conventionally, a screw conveyor with a mesh bottom has been used and dehydration is carried out during the transportation to the incinerator, but sufficient dehydration is performed because it is natural dehydration due to its own weight. I couldn't.

Therefore, attempts have been made to utilize a centrifugal dehydrator in order to perform dehydration more sufficiently, but when a centrifugal dehydrator is used, a slurry is supplied to the inside to prevent overload and blockage. Strict control of concentration and supply is required. However, in reality, since these amounts fluctuate greatly, it was difficult to incorporate the centrifugal dehydrator into a fully automated line. Further, the centrifugal dehydrator is liable to cause troubles in discharging the dehydrated powdery and granular radioactive waste and is not easy to wash, so that there is a problem that it is often necessary to disassemble and repair.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and is capable of automatically dehydrating powdered and radioactive waste such as ion exchange resin, and is difficult to discharge due to blockage. The present invention has been completed to provide a method for dehydrating powdery and granular radioactive waste that does not cause the above.

[0005]

DISCLOSURE OF THE INVENTION The present invention, which has been made to solve the above-mentioned problems, provides compressed air introduced from the upper part of a tank by supplying powdery granular radioactive waste dispersed in water to the inside of a tank for dehydration. To remove water from the bottom of the tank by rotating the rotary blades inside the tank to smooth the surface of the sludge and dehydrate it further with the pressure of compressed air. The feature is that the granular radioactive waste is discharged from the center of the bottom surface of the tank.

[0006]

The present invention will be described in more detail below with reference to the embodiments shown in the drawings. In FIG. 1, 1 is a storage tank for storing powdery and granular radioactive waste such as waste ion exchange resin dispersed in water, 2 is a dehydrating tank having a circular cross section, 3 is dehydrated powdery and granular radioactive waste The material feeder 4 is an incinerator.
A large amount of powdery granular radioactive waste slurry is stored in the storage tank 1, and is supplied by the pump 5 into the dehydration tank 2.

As shown enlarged in FIG. 2, a screen 6 is stretched on the bottom surface of the dehydrating tank 2. At the center of the bottom surface of the tank 2, there are provided a cylinder 7 that can be moved up and down by a mechanism (not shown), and a cap 8 that can seal the upper end of the cylinder 7 and that does not move up and down. Further, a large number of rotary blades 10 are provided at the lower end of a shaft 9 hanging from the center of the ceiling of the tank 2 via a horizontal arm. These rotary blades 10
Is inclined with respect to the radial line of the tank 2, and when the shaft 9 is rotated counterclockwise as viewed from above the tank 2, the granular radioactive waste in the tank 2 is directed toward the central cylinder 7. It has a structure that can be scraped. Next, the dehydration method of the present invention will be described in detail with reference to FIG.

First, as shown in FIGS. 3A and 3B, a slurry of powdery radioactive waste is supplied into the dewatering tank 2 in a state where the cylinder 7 is raised until it comes into close contact with the cap 8. Since the screen 6 is stretched on the bottom surface of the tank 2, the water content in the slurry gradually escapes due to its own weight even if it is left as is. .

When such forced dehydration is carried out, cracks gradually form on the surface of the powdery radioactive waste remaining on the screen 6 as shown in FIG. 3C, and compressed air passes through the cracked portions. Therefore, dehydration cannot proceed. Therefore, in the present invention, as shown in FIG. 3D, the rotary vane 10 is lowered and rotated until it comes into contact with the surface of the powdery radioactive waste, thereby smoothing the surface of the cracked powdery radioactive waste and E of FIG. Compressed air is further supplied from the upper part of the tank 2 as described above. As a result, the compressed air can be prevented from passing through the cracks, so that the air pressure is uniformly applied to the entire surface, and more sufficient dehydration is performed.

After that, the rotary vane 10 is raised as shown by F in FIG. 3, and the central cylinder 7 is lowered to a height such that the upper end thereof coincides with the bottom surface of the tank 2. Then, when the rotary blades 10 are reversed, the sufficiently dehydrated powdery radioactive waste is gradually scraped from its surface toward the central cylinder 7 to form the cylinder 7
Is discharged to the feeder 3 through. In the example, the water content of the granular radioactive waste in the stage C was about 65 to 67%, but the water content of the granular radioactive waste was reduced to about 55 to 60% after the stages D and E. be able to. This value is lower than the water content of 58 to 64% when the centrifugal dehydrator is used.

As shown in FIG. 1, a height meter 11 such as an ultrasonic level meter is attached to the upper surface of the tank 2 to detect the level of the slurry accumulated in the tank 2 and to detect the slurry level by the pump 5. It is preferable to control the supply amount. Such control is effective for fully automatically and efficiently performing dehydration in a real line where the slurry concentration is likely to change.

[0012]

As described above, according to the method for dehydrating powdery and granular radioactive waste of the present invention, powdery and granular radioactive waste such as ion exchange resin can be automatically and sufficiently dehydrated. In addition, there is no problem such as the centrifugal dehydrator that is difficult to discharge due to blockage. Therefore, the present invention has an extremely great contribution to industrial development as a method of dehydrating powdery radioactive waste such as waste ion-exchange resin that solves the conventional problems.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention.

FIG. 2 is a sectional view of a tank portion.

FIG. 3 is a cross-sectional view showing a dehydration process of the present invention.

[Explanation of symbols]

 2 Tank for dehydration 10 rotating blades

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kisaburo Yukimura Ai Prefecture Yabu Town Yabu Town Dairaura, Urauraji 86, Nishimae Nitta 12 (72) Inventor Masamitsu Teramoto Miwa, Kaifu-gun Aichi Prefecture Kida character Ikenoshima No. 93 (72) Masato Matsuda Masato Matsuda, 866 Kanji, Nikkazuka, Kuwana, Mie Prefecture (56) Reference JP-A-53-43200 (JP, A) JP-A-55-16182 (JP, A) JP 61-251798 (JP, A) JP 54-75000 (JP, A)

Claims (1)

[Claims] 1. A particulate radioactive waste dispersed in water is supplied to the inside of a tank for dehydration, water is removed from the bottom of the tank by the pressure of compressed air introduced from the top of the tank, and then rotary blades inside the tank. Is rotated to smooth the surface of the sludge and further dehydrated by the pressure of compressed air, and then the rotary vanes are reversed to discharge the dehydrated powdery granular radioactive waste from the center of the bottom surface of the tank. Method for dehydrating granular radioactive waste.