JPS59200999A - Method of melting and solidifying incineration ash of radioactive waste - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for melting and solidifying incinerated ash of radioactive waste, and more specifically, when incinerating radioactive waste ash is melted and solidified using an induction heating furnace, the furnace body serves as a heating element. This invention relates to a method of melting and solidifying incinerated ash to reduce its volume using graphite.

Conventionally, radioactive waste has been incinerated in an incinerator to reduce its volume, and then stored in containers for disposal. When storing incinerated ash, it is not only easy to scatter during transportation, but also because incinerated ash is water-soluble, it has extremely poor leaching resistance during storage, and also has low thermal conductivity, so the temperature at which radioactive elements decay The container was easily damaged during ascent and lacked long-term storage stability. Furthermore, there are also disadvantages such as the inability to process a large amount of incinerated ash because the density inside the container during storage is low.

In order to compensate for these drawbacks, methods of solidifying incinerated ash are effective, and for example, (1) cement solidification method and (2) asphalt solidification method have been proposed. However, this cement solidification method uses a large amount of cement, so the volume increase is significantly inferior to the volume reduction rate, and the leaching resistance is inferior. On the other hand, although the asphalt assimilation method reduces the volume to some extent, there are problems with fire resistance and strength. Then, in recent years, methods such as (3) plastic assimilation method, (4) glass assimilation method, (5) ceramic assimilation method, and (6) microwave assimilation method have been introduced as solidification methods to replace cement assimilation method and asphalt solidification method. Among these methods, the glass assimilation method, ceramic assimilation method, and microwave assimilation method are methods that melt and solidify incinerated ash, and eliminate to some extent the drawbacks of the cement assimilation method. In this method, the incinerated ash is melted in a melting furnace, and when the ash is taken out, a tilting device is used to tilt the furnace body and transfer it to another container, which wastes a considerable amount of time.In addition, the equipment is large-scale, so it consumes electricity and work space. In addition, in the vitrification method and ceramic solidification method, since the heating element is metallic, it must be melted at the lowest possible temperature. Since a melting point depressant is added to the incineration ash, there is a disadvantage that the volume reduction rate is slightly inferior due to the increase in the amount of solidified material.On the other hand, the microwave melting method has the disadvantage that the incineration ash contains conductors such as metals and unburned carbon. Therefore, there is a problem that heating cannot be performed by discharging, and therefore, unless these conductors are removed, melting cannot be performed, which makes the work process complicated.

The present invention has been made in order to solve the above-mentioned problems, and in addition to increasing the volume reduction incineration and assimilation capacity of incinerated ash, it also improves the efficiency and economy of radioactive waste incineration by reducing the size of the device. The purpose is to provide a method for melting and assimilating ash.

As a result of studies in line with the above objectives, the present inventors found that when melting and solidifying radioactive waste incineration ash using an induction heating furnace,
The inventors have discovered that the above object can be achieved by using graphite as the furnace body of an induction heating furnace and using the graphite as a heating element, and have arrived at the present invention.

The present invention is characterized in that graphite, which serves as a heating element, is used as the furnace body when incineration ash of radioactive waste is melted and solidified in an induction heating furnace, and further, the lower part of the hollow part of the furnace body or A reservoir is provided at the bottom, and the reservoir has an inclination toward the take-out hole located in the center, and the take-out hole is closed by fitting the tabs 1 to 2, and the incineration put into the furnace body is closed. The ash is melted in the reservoir, and when the desired amount is reached, the stopper is pulled up to open the take-out hole, and the molten material is collected into a container below the furnace body. In the melt assimilation method.

Hereinafter, the present invention will be specifically explained using the drawings.

FIG. 1 is a schematic diagram of a melting and solidifying process according to one embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a furnace body portion according to another embodiment of the present invention.

In FIG. 1, incinerated ash 1 of radioactive waste is temporarily stored in an incinerated ash popper 2, and the incinerated ash 1 is appropriately passed through an incinerated ash supply pipe 3 to a hollow-shaped high-frequency induction heating furnace 4. It is supplied to a reservoir 6 at the bottom of the furnace body 5 made of graphite. The reservoir 6 is provided with a takeout 7L 7 at its center.
has an inclination toward the extraction hole 7. and extraction hole 7
The distal end of the stopper 9 which is raised and lowered by a transfer means such as a stopper raising/lowering m8 is fitted to close the extraction hole 7. When the desired amount of incinerated ash 1 is filled in the reservoir 6 of the furnace body 5, the high-frequency induction heating furnace 4 is heated by the high-frequency power supply 10, the furnace body 5 made of graphite functions as a heating element, and the incinerated ash 1 is melted. It solidifies to become a melt 11. When the incinerated ash 1 completely becomes the molten material 11, the stopper 9 is appropriately lifted up by the stopper elevator 8, the extraction hole 7 is opened, and the molten material 11 falls from the extraction hole 7 under its own weight into the canister 12, where it cools and solidifies. do. In FIG. 2, the reservoir 6 is the furnace body 5.
The position of the reservoir 6 in the furnace body 5 is not particularly limited as long as it can fill the desired amount of incinerated ash 1, but in consideration of economical processing, it may be located at the lower part or the bottom. , preferably at the bottom. Moreover, the extraction hole 7 is the second
As shown in the figure, it is desirable to have a slope so as to suitably fit with the tip of the stopper 9. Melt 1
1 falls into the canister 12, the stopper elevator 8 descends, the tip of the stopper 9 refits into the take-out hole 7, the take-out hole 7 is closed, and new incinerated ash flows from the incinerated ash supply pipe 3 into the furnace body. 5 is filled, and the canister 12 is repeatedly melted and solidified until it is filled with the cold N1 melt 11.

When the canister 12 is full, the solidified melt 11 is transported by the transfer device 13 to a storage location and stored in a storage container 14 such as a drum can. The generated waste gas is transferred to waste gas pipe 1.
5 and, if necessary, processed in the waste gas treatment system of the incinerator to remove radiation.

As described above, in the present invention, the take-out hole is provided in the reservoir of the furnace body, and since the reservoir is inclined toward the take-out hole, the stopper can be moved downward by its own weight simply by moving the stopper up and down. Since the ash falls into a canister and is cooled and assimilated, continuous processing is possible, which improves the processing capacity of incinerated ash, and reduces the heating and melting furnace equipment to the minimum necessary, making it highly economical and workable. A melt assimilation method can be provided. In addition, since the present invention uses an induction heating furnace,
There is no need for a pre-treatment step to remove conductors such as small metal pieces and unburned carbon. Furthermore, since graphite is used as the heating element in the present invention, heat treatment can be performed at a higher temperature than in glass assimilation methods that use metal as the heating element, and the furnace body is consumed and becomes unusable. When this occurs, it can be incinerated as is, which has the advantage of not generating new waste.

Therefore, the present invention is suitably used as a method for melting and solidifying incineration ash of radioactive waste.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a melting assimilation process according to one embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a furnace body portion according to another embodiment of the present invention. 1: Incineration ash, 2: Incineration ash hopper, 3: Incineration ash supply pipe, 4: High frequency induction heating furnace, 5: Furnace body, 6:
Reservoir part, 72 extraction holes, 8: Stopper lift machine, 9 Varnish 1-Brim 110: High frequency power supply, 11: Melt, 12
: Canister, 13: Transfer device, 14: Storage container, 15: Waste gas pipe. Patent Applicant JGC Corporation Company Agent Patent Attorney Tatsuo Ito Agent Patent Attorney Tetsuya Ito

Claims (1)

[Claims] 1. A method for melting and assimilating radioactive waste incineration ash, characterized in that graphite serving as a heating element is used as a furnace body when melting and solidifying incineration ash of radioactive waste in an induction heating furnace. 2. When incineration ash of radioactive waste is melted and solidified in an induction heating furnace, a hollow graphite which serves as a heating element is used as the furnace body, and a reservoir is provided at the bottom or bottom of the hollow part of the furnace body. The reservoir has an inclination toward the take-out hole located at the center, and the take-out hole is closed by fitting a stopper, and the incinerated ash introduced into the furnace body is melted in the reservoir to the desired m
A method for melting and solidifying incinerated ash, characterized in that when the stopper is pulled up to open the extraction hole, the molten material is collected in a container below the furnace body.