JPS6038698A - Device for melting and solidifying radioactive waste incinerated ash - 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 an apparatus for solidifying radioactive waste, and more particularly to an apparatus for melting and solidifying incinerated ash of radioactive waste.

Conventional waste contaminated with radioactivity generated from facilities handling A4 radioactive materials such as nuclear power plants is generally incinerated, and the incinerated ash is filled into drum cans, etc. They are usually stored in an appropriate location within the facility. However, since these incinerated ash are in the form of powder and granules, it is desirable to stabilize and reduce the volume of the incinerated ash before transporting or storing the drum can filled with incinerated ash, and various methods for this treatment are being researched. .

Recently proposed methods for treating incinerated ash include a method of solidifying incinerated ash with cement, and a method of mixing asphalt, plastic, etc. with incinerated ash and solidifying it. However, in the 0i1 method of solidifying incineration ash with cement, (1) In order to mix ash and cement to obtain a solidified material with stable density, strength, etc. On the other hand, it is necessary to use a cement of 4 or more, which results in an increase in the volume of the solidified body as it becomes larger than the volume of the ash.

(2) When mixing ash and cement, metal contaminants in the incinerated ash react with the alkaline aqueous solution of cement to generate hydrogen gas, which creates voids in the solidified material and reduces density, strength, etc. and lacks stability. Therefore, in order to solve the problem of stiffness, pretreatment to prevent the generation of hydrogen gas is required, which complicates the apparatus.

There were drawbacks such as. In addition, the latter method or device for solidifying incinerated ash with asphalt, plastic, etc. requires pretreatment such as removal of metal pieces from incinerated ash and pulverization, which has the disadvantage of requiring complicated and large-sized equipment.

The present invention solves the above-mentioned conventional drawbacks, and provides a melting and solidifying device capable of melting and converting granular radioactive waste incineration ash into a stable, volume-reduced solidified material suitable for transportation and storage. The gist of the furnace is a sealed container-like furnace body whose bottom can be opened by a bottom lid that is driven up and down, and an induction heating coil installed on the outer periphery of the side wall of the furnace body. a metal cylindrical heating element disposed inside the furnace body at a position corresponding to the induction heating coil; and a metal cylindrical heating body disposed inside the furnace body at a position corresponding to the induction heating coil; and the furnace body mounted on a support fixed to the bottom lid and supported by the bottom lid. a bottom plate that substantially closes the lower end of the cylindrical heating body when the bottom is closed; a container that is placed on the bottom plate and can be inserted into and removed from the cylindrical heating body;
The exhaust gas port provided at the top of the furnace body, the inert gas supply provided in the bottom cover]-1, and the gas supplied from the inert gas supply 1 formed in the furnace main body are fed into the cylindrical shape. a gas flow path that guides one gas through the inside and outside of the heating body; an incineration ash supply port that is attached to the furnace body and supplies radioactive waste incineration ash into the container; The oxygen-containing gas is taken into the main body and into the container,
1lffi (=1
An apparatus for melting and solidifying radioactive waste incineration ash is provided with a detection device for detecting a molten state in a container.

S1: An embodiment of the present invention will be explained with reference to the drawings.

), the furnace body 2 is in the shape of a closed container supported by a supporting frame l (on the foundation), and has a cylindrical side wall 3 made of a non-metallic material, for example quartz, and a metal covered with the side wall 3. It consists of a lid part 4 made of A bottom cover 7 that freely closes the bottom of the furnace body 2 is fixed to a lifting platform 6 that is guided by a guide 5 erected on the foundation and is driven up and down by a driving device such as a motor (as shown in the figure). It is. 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, there is a cylindrical heat insulating material 1. made of asbestos, castable, etc. ! A metal cylindrical heating element I2 is provided inside the heat insulating wall 11 at a position corresponding to the induction heating coil 8, and an outer space 13 is formed between the heat insulating wall 11 and the heat insulating wall 11. . A heat insulating lid 15 with a hole 14 is attached to the upper end of the heat insulating wall 11.
A small gap 16 is formed between the heating element 15 and the cylindrical heating element 12. The heat insulating 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, when the bottom of the furnace body 2 is closed by the bottom cover 7, a cylindrical heating body 1
The bottom plate 19 that closes the lower end of 2 is a single piece. The material of this bottom plate 19 is preferably a metallic AA material, but may be a non-metallic material. A container 20 made of a non-metallic material such as carbon graphite 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 the base 18 integrated therewith,
It can be inserted into and removed from the cylindrical heating body 12 from below. Bottom plate 19
An inert gas supply port 21 is provided in the support base 18, and a slotted hole 22 communicating with this supply port and four radial grooves 23 communicating with the upper end of this hole 22 and opening upward are bored in the support base 18. It is. Further, the bottom plate 19 is provided with a ventilation hole 25 that communicates the inner space 24 between the field R820 and the cylindrical heating element 12 with the groove 23 of the bottom plate [9]. υ1 gas slot 26 is provided. As a result, an outer gas flow passage 27 runs from the inert gas supply port 21 through the hole 22, the groove 23, the outer space 13, the gap 16, and the hole 14 to the exhaust gas port 26, and similarly, the flow branches off from the groove 23 to the ventilation hole 25, An inner space 24 and an inner gas flow passage 28 leading to the exhaust gas port 26 via the hole i4 are formed. The lid 4 of the furnace body 2 also has an incineration ash supply port 31 for supplying radioactive waste incineration ash into the container 20, and a combustion port 31 for incineration necessary to burn unburned content in the incineration ash into the container 20. An oxygen supply pipe 32 for supplying air and the like and a thermometer 33 such as a radiation thermometer for detecting the molten state inside the container 20 are installed by penetrating the lid 4, respectively.

Radioactive waste incineration ash melting and solidification device 3 having the above configuration
4, 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. Furthermore, if the container 20 is made of metal, induction heating of the container itself is also applied. 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 fill the inside and outside of the cylindrical heating element 12, that is, the inner space 24 and the outer space 13, with an inert gas atmosphere. shall be. Then, radioactive waste incineration ash is supplied into the container 20 from the incineration ash supply port 31, and at the same time, combustion air or other oxygen-containing gas is supplied into the container 20 from the oxygen supply pipe 32. The fuel is burned, and the ash is heated and melted at high temperatures. At this time, if the melting point of the incinerated ash is high, a flux that forms a eutectic with the incinerated ash,
For example, boric acid, borax, sodium carbonate, etc. may be supplied into the container 20 together with the incinerated ash, or only this flux may be first supplied into the container 20 from the incinerated ash supply port 31 and heated and melted to form a liquid. The melting process may be performed by supplying incineration ash to the second part. For example, Si
O□ is 35 to 45 wt%, A, +203, C + hO1M
gO is 12-17wL%, Fe2O2 is s~13w, respectively.
Incineration ash with a chemical composition that contains a small amount of Na 20 and zllo J' has a melting point of about 1200°C and requires a melting operation at a fairly high temperature.
If boric acid, borax, sodium carbonate, etc., which form a eutectic with the incinerated ash as described in 11, are used as a flux, it will be 900~
It can be melted at a heating temperature of about 1100°C. During the above melting operation, the melting state inside the container 20 can be detected by the thermometer 33. Note that a liquid level gauge, a monitor television, or the like may be used instead of the thermometer 33 or in combination with the thermometer. 1 and 4 The gas inside the main body 2 is sucked through the exhaust gas port 26 and cleaned using a filter or the like. When the molten material in the container 20 reaches a predetermined amount, the furnace body 2 is cooled by natural cooling, and when the molten material is solidified and fixed in the container 20, the lifting platform 6 is moved. Lower the container 20, remove it from the bottom plate 19, and replace it with a new container 2o.
is mounted on the bottom plate 19, and the same steps as above are repeated.

Incidentally, all non-combustible impurities such as metals, bricks, and glass mixed in the incineration ash 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. Still inert gas supply port 2
1 to the inner circumference and outer circumference 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 around the abutment 18, for example. 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.

As explained above, according to the present invention, granular radioactive waste incineration ash with a small bulk specific gravity can be confined in a container as a small-volume inorganic solidified body using an induction heating furnace type device with a simple structure, In particular, since it is equipped with an Oxygen Ino (supply pipe), even incineration ash containing a large amount of unburned matter can be solidified stably.In addition, a container is placed inside a metal cylindrical heating body for induction heating. Therefore, the shape of the cylindrical heating element,
Incineration ash can be heated efficiently by selecting the material. Furthermore, since the inside and outside of the one-sided heating element and the outside of the container are kept in an inert gas atmosphere, there is little oxidation loss even at high temperatures, and the life of the device is long.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a melting and solidifying apparatus showing an embodiment of the present invention. 2... Furnace body, 6... Lifting platform, 7... Bottom cover, 8...
...Induction heating coil, 12...Cylindrical heating body, 13...
・Outside space, 18... Abutment, 19... Bottom plate, 20.
...Container, 21...Inert gas supply port, 24...Inner space, 26...υ1 gas flow path, 27...Outer gas flow path, 28...Y inner gas flow path, 31...・Incineration ash supply port, 3'2...Oxygen supply pipe, 33...Thermometer, 34
...Melting and solidifying equipment. Applicant Tokyo Electric Power Co., Ltd. Nippon Insulators Co., Ltd. Agent Masao Inui

Claims (1)

[Scope of Claims] 1. 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 interior of the furnace body. A metal cylindrical heating body disposed at a position corresponding to the induction heating coil, and a support 11y fixed to the bottom cover,
(1) a bottom opening that substantially closes the lower end of the cylindrical heating body when the bottom of the spider body is closed by the bottom cover; and an exhaust gas 1 provided at the top of the furnace body,
At the bottom of the above, there is one inert 11. a gas supply port, a gas flow passage formed in the furnace body and guiding the gas supplied from the inert gas supply port to the exhaust gas outlet through the inside and outside of the cylindrical heating body; and the furnace body. An incineration ash supply port that supplies radioactive waste incineration ash into the container; an oxygen supply pipe that is attached to the furnace body and supplies oxygen-containing gas into the container; An apparatus for melting and solidifying radioactive waste incineration ash, comprising a detection device attached to the container to detect the molten state within the container. 2. Radioactive waste incineration according to claim 1, wherein the container is a metal container. Ash melting and solidifying device. 3. The radioactive waste incineration ash melting and solidifying device according to claim 1 or 2, wherein the oxygen supply pipe is a combustion air supply pipe. 4. Detecting the molten state in the container. The apparatus for melting and solidifying radioactive waste incineration ash according to claim 1, 2, or 3, wherein the detection device is an anchor temperature meter.