JPS6114597A - Method and device for melting and solidifying 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 (Field of Industrial Application) This invention relates to a method and apparatus for melting and solidifying radioactive waste.

(Prior technology) Among radioactively contaminated waste generated from radioactive material handling facilities such as nuclear power plants, radioactive waste with a low bulk density, such as HEPA filters and various heat insulating materials, is processed by pressure. It is compressed and reduced in volume and stored in a V-ram.

(Problem to be solved by the invention) However, according to the above method, even if the compression pressure is increased,
A volume reduction rate of only 1/2 to 1/4 can be obtained. Therefore, the incineration ash of radioactive waste is heated and melted in a container.
One possible method is to pour the above-mentioned radioactive waste with a low bulk density into the molten metal and melt it, but in this case, the waste floats on the surface of the molten metal and comes into contact with the molten metal only on the bottom surface, resulting in a slow melting rate. , processing capacity is inferior.

This invention solves the above problems, and can efficiently melt radioactive waste with a small bulk density to obtain a solidified material whose volume is reduced to 141. It is an object of the present invention to provide a method and apparatus for melting and solidifying radioactive waste, which can be melted and solidified at the same time as radioactive waste using the same equipment.

(Means for solving the problem) This invention method is based on a furnace equipped with an induction heating coil.
A container is placed inside the chamber, and the container is heated by the induction heating coil to melt the powdery radioactive waste inside the container, and the radioactive waste with a low bulk density is forced into the resulting melt and melted. This is a method for melting and solidifying radioactive waste, which is characterized in that it is then cooled to obtain a solidified body fixed in the container, and the apparatus of this invention is capable of opening the bottom part by means of a bottom lid that is driven up and down. A furnace body in the form of a sealed container closed to the inside, an induction heating coil provided on the outer periphery of the side wall of the furnace body, and an induction heating coil disposed inside the furnace body at a position corresponding to the induction heating coil and fixed to the bottom cover. A metal container is placed on a support base and can be inserted into and removed from the furnace body from below; an input chute for supplying radioactive waste to the input chute, a pressing device that drives up and down a pushing plate disposed in the input chute so as to be able to move up and down, and a detection device attached to the furnace body to detect the molten state in the container. This is a radioactive waste melting and solidification equipment equipped with:

In this invention 1, granular radioactive waste refers to powdery or granular waste such as incinerated ash of radioactive waste, sodium sulfate and sodium borate obtained from liquid radioactive industrial waste.

Furthermore, in the present invention, radioactive waste having a low bulk density refers to bulky solid waste such as HEPA filters, glass filters, and various types of heat insulating material.

(Function) In this invention, radioactive waste having a small bulk density is ascended to a pressing device and pressed into a molten metal obtained by melting powdery radioactive waste by induction heating in a container, thereby allowing the waste to be disposed of. The contact area of the object with the molten metal increases greatly, resulting in a high melting rate.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows an apparatus for melting and solidifying radioactive waste according to the present invention, in which a furnace body 2 in the form of a closed container supported by a support frame 1 erected on a base is made of a cylindrical cylinder made of a non-metallic abrasive material, for example quartz. It consists of a shaped side wall 3 and a metal lid 4 attached to the side wall 3. A bottom cover 7 for freely closing the bottom of the furnace body 2 is fixed to a lifting platform 6 that is guided to be raised and lowered by a guide 5 set up on a foundation and driven up and down by a drive unit such as a motor (not shown). be. An induction heating coil 8 is attached to the outer periphery of the side wall 3. This induction heating coil 8 is housed within a cover 9 and is cooled by a known cooling method such as air cooling or water cooling. On the other hand, inside the side wall 3 of the furnace body 2, a cylindrical insulation wall 11 made of a heat insulating material such as asbestos or castable is provided. A cylindrical heating body 12 is provided, and an outer space 13 is formed between it and the heat insulating wall 11. A hole 14 is provided at the upper end of the heat insulating wall 11.
A heat insulating lid 15 is attached, and a small gap 16 is formed between the heat insulating lid 15 and the cylindrical heating element 12. The IR hot wall 11 and the cylindrical heating body 12 are fixedly supported by the furnace body 2 or the supporting frame 1. On the other hand, a bottom plate 19 that closes the lower end of the cylindrical heating element 12 when the bottom of the furnace body 2 is closed by the bottom cover 7 is mounted on a non-metallic support 18 such as a heat insulating material fixed to the bottom M7. . The material of this bottom plate 19 is preferably a metal material, but may be a non-metal material. A container 2o made of a non-metallic material such as carbon gutsphite or ceramic, preferably a metallic material such as stainless steel, is placed on the bottom plate 19.

The container 20 is driven up and down together with the bottom cover 7 and a supporting base 18 integrated therewith, and can be freely inserted into and removed from the cylindrical heating element 12 from below. The bottom plate 19 is provided with an inert gas supply port 21 , and a hole 22 communicating with the supply port 21 and four radial grooves 23 communicating with the upper end of the hole 22 and opening upward are provided on the support base 18 . It's murder. The bottom plate 19 also includes the container 2.
A ventilation hole 25 is provided to communicate the inner space 24 between the heating element 12 and the cylindrical heating element 12 with the groove 23 of the bottom plate 19, and a protrusion slot 26 is provided in the upper part of the furnace body 2.

As a result, the inert gas supply port 21, the hole 22, the groove 23
, outer space 13, gap 16, hole 14 to #γλ port 2
6, and an inner solenoid flow passage 28 which is similarly separated from the groove 23 and reaches the exhaust gamma slot 26 via the ventilation hole 25, the inner gllI space 24, and the hole 14. . Further, the lid part 4 of the reactor body 2 is provided with a waste supply device 31 that supplies radioactive waste into the container 20, and a waste supply device 31 that supplies radioactive waste into the container 20.
An oxygen supply pipe 32 that supplies combustion air necessary to burn the unburned content in the incineration ash, and a thermometer 33 such as a radiation thermometer that detects the molten state inside the container 20 are connected to the lid. It is installed by penetrating 4.

FIG. 2 shows details of the waste supply device 31, in which a vertical tubular input chute 35 fixed to the lid 4 of the furnace body 2 passes through the heat insulating lid 15 and opens above the container 20. At the top of the input chute 35, there are a powder input port 36 for inputting granular radioactive waste (hereinafter referred to as powder) and a solid input port 37 for inputting radioactive waste with a small bulk specific gravity (hereinafter referred to as solid). It is a provision. A push plate 38 is disposed within the input chute 35 so as to be movable up and down, and a piston rond of an air cylinder 39, which is a pressing device for driving the push plate 38 up and down, is connected to the push plate 38. 40 is a guide bar for guiding the push plate 38. Further, a slide damper 41 is attached to the input chute 35 below the powder input port 36 and the solid input port 37 so as to be openable and closable.

In the radioactive waste melting and solidifying apparatus 43 having the above configuration, when the induction heating coil 8 is energized to heat the cylindrical heating body 12, the container 20 is heated by heat radiation and heat transfer from the heating body 12. In addition, if the container 20 is made of metal, induction heating of the container itself is also added. In addition, an inert gas such as argon or nitrogen gas is supplied into the furnace body 2 from the inert gas supply port 21 to create an inert gas atmosphere inside and outside the cylindrical heating element 12, that is, the inner space 24 and the outer space 13. do. Then, powder 44 of incineration ash of radioactive waste, sodium sulfate, sodium borate, etc. obtained from liquid radioactive waste is introduced into the container 20 from the powder input port 36 through the input chute 35. At this time, the slide damper 41 is opened, but after it is turned on, it is closed to cut out the heat. The charged powder 44 is heated and melted by the container 20 heated to about 1100°C to form a molten body 45 having a surface temperature of about 950 to 1050°C. During the above melting operation, if combustion air or other oxygen-containing gas is supplied into the container 20 from the oxygen supply pipe 32 as needed, even if there is unburned content in the incinerated ash, it will be combusted and the ash will be and melts. Furthermore, if the melting point of the incinerated ash among the powders 44 is high, a flux that forms a eutectic with the incinerated ash, such as boric acid, borax, sodium carbonate, etc., may be supplied into the container 20 together with the incinerated ash. In addition, only this flux is first poured into the powder inlet 36.
Alternatively, the radioactive waste may be heated and melted into the container 20 (20) to form a liquid, and then powdered radioactive waste such as incinerated ash may be fed thereon to perform the melting process.

During the above melting operation, the melting state inside the container 20 can be detected by the thermometer 33. Furthermore, this thermometer 3
In place of 3, or in combination with a thermometer, a liquid level gauge, monitor TV, etc. may be used.

When a predetermined amount of the molten material (molten metal) 45 of the powder 44 is formed in the container 20, a lightweight solid 46 such as a HEPA filter or various heat insulating materials is dropped from the solid inlet 37 through the input chute 35 onto the molten material 45. do.

At the time of this dropping, the slide gunba 41 is opened in the same manner as described above. This solid 46 is pushed into the pushing plate 3 by driving the air cylinder 39.
As shown in Fig. 1, a plurality of solids 46 that can be accommodated in the input chute 35 are charged, and then the top part is pressed, and when one solid 46 melts, the top part is pressed. It is preferable to add a new solid 46 and press it. Finally, as shown in FIG. 2, the final solid 46 is pushed into the container 20 near the top. Melt body 45
The solid 46 pushed inside the melt 45 over a very wide area.
It melts reliably in a short time when it comes into contact with.

The pushing speed of the solid 46 by the air cylinder 39 and the amount of power input to the induction heating coil 8 are adjusted while the surface temperature of the melt 45 is detected by the thermometer 33.

In each of the above steps, the gas inside the furnace body 2 is sucked through the slot 26 and purified using a filter or the like. container 20
When the molten material in the furnace reaches a predetermined amount, the furnace body 2 is allowed to cool naturally, and the molten material solidifies in the container 20.
Once the container 20 is fixed inside, the lifting table 6 is lowered, the container 20 is removed from the bottom plate 19, a new container 20 is mounted on the bottom plate 19, and the same steps as described above are repeated. Incidentally, all non-combustible impurities such as metals, bricks, and plastics mixed in the waste are also incorporated into the molten material in the container 20 and fixed.

The present invention is not limited to the above-mentioned embodiment, and the heat insulating wall 11 and the heat insulating lid 15 may be omitted, for example, if the furnace body 2 has good heat insulation properties. Also, inert gas supply port 2
1 to the inner and outer circumferences of the cylindrical heating element 12 do not pass through the abutment 18 and the bottom plate 19, but instead are formed through holes drilled in the cylindrical heating element 12 from, for example, around the abutment 18. Alternatively, the inert gas may be allowed to flow into the inner space 24 through a gap formed between the cylindrical heating element 12 and the bottom plate 19, or depending on the material of each part and the operating temperature, the inert gas may be allowed to flow. can also be omitted. Further, in the above embodiment, the container 20 is indirectly heated by the induction heating coil 8 via the cylindrical heating body 12, but the metal container 20 is heated by the induction heating coil 8 without using the cylindrical heating body 12. Alternatively, the waste may be melted by direct heating.

(Effects of the Invention) As explained above, according to the present invention, () (a solidified material whose volume is greatly reduced by efficiently melting radioactive waste having a small bulk density such as an EPA filter or a heat insulating material) Furthermore, it can be melted and solidified using the same equipment at the same time as powdered radioactive waste such as radioactive waste incineration ash.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a melting and solidifying apparatus showing an embodiment of the present invention, and FIG. 2 is a detailed longitudinal cross-sectional view of a portion of the waste supply apparatus. 2... Furnace body, 6... Lifting platform, 7... Bottom cover, 8...
...Induction heating coil, 12...Cylindrical heating body, 18...
・Abutment, 19... Bottom plate, 20... Container, 26...
Wandering slot, 31... Input chute, 38... Pushing plate, 39... Air silling (pressing device), 43... Melting solidification device, 44... Powder (radioactive waste), 45・
...Melted body, 46...Solid (radioactive waste). 7th page q8 Kaisho Gl-14597 (5) 2nd

Claims (1)

[Claims] 1. A container is placed in a furnace equipped with an induction heating coil, and the container is heated by the induction heating coil to melt powdery radioactive waste in the container, resulting in a molten product. A method for melting and solidifying radioactive waste, which comprises melting radioactive waste while pushing it into the container, and then cooling it to obtain a solidified body fixed in the container. 2. Radioactive waste according to claim 1, in which the powdery radioactive waste comprises at least one of the following: incineration ash of radioactive waste, sodium sulfate obtained from liquid radioactive waste, and sodium borate. Melting solidification method. 3 Radioactive waste with low bulk specific gravity is used in HEPA filters,
The method for melting and solidifying radioactive waste according to claim 1 or 2, comprising at least one of a glass filter and a heat insulating material. 4. A method for melting and solidifying radioactive waste according to claim 1, 2, or 3, wherein a metal cylindrical heating body is provided in the furnace, and a container is installed in the cylindrical heating body. . 5. The method for melting and solidifying radioactive waste according to claim 1, 2, or 3, wherein the container is made of metal and the container is directly heated by an induction heating coil. 6. A furnace body in the form of a sealed container whose bottom part is releasably closed by a bottom lid that is driven up and down, an induction heating coil provided on the outer periphery of a side wall of the furnace body, and an induction heating coil provided inside the furnace body. a metal container placed on a support fixed to the bottom cover and placed at a position corresponding to the coil, and capable of being inserted into and removed from the furnace body from below; an exhaust gas port, an input chute that is attached to the furnace body and supplies radioactive waste into the container, a pressing device that drives up and down a push plate that is movably disposed in the input chute, and is attached to the furnace body. and a detection device for detecting the molten state in the container. 7 A metal cylindrical heating element is placed inside the furnace body around the outer periphery of the container, and the container is placed on a bottom plate that substantially closes the lower end of the cylindrical heating element when the bottom of the furnace body is closed by the bottom cover. An apparatus for melting and solidifying radioactive waste according to claim 6.