JPS6319039B2 - - Google Patents

Description

Detailed Description of the Invention This invention applies to waste generated in facilities that handle radioactive materials such as nuclear power plants (hereinafter referred to as radioactive waste, including radioactive materials themselves and materials contaminated with radioactive materials). This relates to a melting furnace for radioactive waste, which is used to melt radioactive waste for volume reduction treatment.

The purpose of this is to be able to melt the radioactive waste packed in the container together with the container, and in the case of melting, the melting work can be done very efficiently, and furthermore, in that case, the work can be done very efficiently. The objective is to provide a radioactive waste melting furnace that can ensure the safety of personnel.

The drawings showing the embodiments of the present application will be described below. The furnace body 1, which is configured to have an airtight interior, is configured to be vertically divided into two parts, an upper furnace body and a lower furnace body. The upper furnace body is composed of an upper furnace shell 2, and the lower furnace body is formed into a concave shape as shown in the figure by a lower furnace shell 3 and a refractory material 4 covering the inner surface thereof. . As the refractory material 4, graphite oxide (composition is 10 to 30% graphite and the remainder is alumina or magnesia), also called carbonaceous brick, is used. This is because a plasma torch is used as a heating device, which will be described later.
It is used for the purpose of enabling electricity to flow between the lower furnace shell 3 and the melt 31. Reference numeral 5 indicates a dummy material inserted into the inner surface of the refractory material 4. As the dummy material 5, for example, a waste iron material having a size of about the size of a stone is used, and the iron materials are randomly charged so that there are gaps between them. Reference numeral 6 indicates a sump formed above the dummy material 5, in which a molten material 31 exists. Reference numeral 7 indicates a spout formed on the side of the water reservoir 6. 8
indicates a downstream port, and a runner 9 through which the melt flows is formed between the spout 7 and the downstream port 8.
Next, reference numeral 10 denotes a cooling rod, which is configured to move forward and backward in the direction of the arrow by means of a device not shown. This cooling rod 10 has a double pipe structure as shown in the figure, and a cooling fluid (for example, cooling water) is passed through the inside through water ports 11 and 12. Reference numeral 13 indicates an electromagnetic coil provided under the lower furnace shell 3, and is provided for stirring the melt 31 and controlling the direction of the plasma arc, which will be described later.

Next, reference numeral 15 indicates a guide cylinder provided substantially vertically in the center of the upper furnace shell 2, and its inner diameter is formed to a size that allows one melting container 30 to be inserted therethrough. Further, its length is set to a length that allows a plurality of melting containers 30 to be inserted in tandem. Also, the axis 15a of this guide tube 15 is aligned with the trough 6 as shown in the figure.
The lower end 15b of the guide tube 15 faces the trough 6. Note that the distance between the lower end 15b and the water reservoir 6 is made shorter than the length of one container 30. Reference numeral 16 denotes a closing device provided at the upper end of the guide cylinder 15, and is constructed so that the loading port 18 can be opened and closed by a door 17 that can be moved in the direction of the arrow by a cylinder not shown. Next, the heating device attached to the upper furnace shell 2 will be explained. 21 is a plasma torch, supporting device 2
0, it is attached so that it can freely move forward and backward in the direction of the arrow. 23 is a plasma torch supporting device 22
It is configured such that it can be freely tilted in the direction of the arrow. That is, the support device 22 includes a support body 24 fixed to the furnace shell 2. The inner surface of the support body 24 is a spherical surface, and a rolling element 25 whose outer surface is a spherical surface is provided inside the supporting body 24. The plasma torch 23 is attached to this rolling element 25, and the plasma torch 23 is moved in the direction of the arrow. It is now possible to tilt. Note that a plurality of the plasma torches 21 may be arranged on a circumference centered on the axis 15a of the guide tube 15. Next, 26 indicates an exhaust port formed in the upper part of the upper furnace shell 2. Reference numeral 27 indicates an in-furnace condition monitoring device provided in the upper furnace shell 2, which monitors the melting state of waste in the sump 6 and the inside of the guide tube 15 through a vertically elongated opening 28 formed in the guide tube 15. The charging state of the containers 30 can be monitored. Reference numeral 29 indicates a monitoring device provided in the lower furnace shell 3, which is capable of monitoring the status of the spout 7.

In the case of the above structure, the dummy material 5 is charged inside the lower furnace body in advance, and the upper part of the dummy material 5 is melted by the plasma arc emitted from the plasma torches 21 and 23, and the molten material 31 is Existing cisterns are formed.

On the other hand, the door 17 of the closing device 16 is opened, and a large number of containers 30 filled with radioactive waste are loaded into the guide tube 15 from the charging port 18 in tandem. In the state where the container 30 is charged in this way, the container 30 at the lower end holds the melt 30 present in the tundish 6.
The container 30 is in a state of being immersed in water, and a plurality of containers 30 are further stacked on top of it. After charging the container, the charging port 18 of the closing device 16 is closed to the door 1.
Closed by 7. In such a state, the container 30 existing at the lower end and the radioactive waste inside thereof are heated by the melt 31 and the plasma arc emitted from the plasma torches 21 and 23, and are melted. As the melting progresses, the container 30 at the lower end and the unmelted portion of the waste therein are pushed by the weight of the container 30 and by other containers located above the container. As a result, the unmelted portion is always immersed in the molten material 31 of the tundish basin 6 from its lower end. Therefore, the container 30 and the waste inside thereof are melted continuously without interruption. In the case of the above-mentioned melting operation, the magnetic field of the electromagnetic coil 13 is applied to the molten metal 31
The above-mentioned melting is performed appropriately by stirring the plasma or by appropriately controlling the direction of the plasma arc emitted from the plasma torches 21 and 23. Melt 31 made by the above operation
The extraction is performed as follows. That is, the plasma torch 23 is tilted around the support device 22, and the solidified material present in the spout 7 is irradiated with a plasma arc emitted from the plasma torch 23, thereby melting the solidified material. Then melt 3
1 flows out from the spout 7, passes through the runner 9, and flows downward from the flow port 8. The melt thus discharged is taken into a storage container and solidified there, solidified into blocks, or granulated by various solidifying means.

Next, when stopping the outflow of the molten material 31, the plasma torch 23 is returned to its original position, and the cooling rod 10, through which cooling fluid is passed through the water holes 11 and 12, is directed toward the spout 7. The tip of the cooling rod 10 is inserted into the melt existing in the spout 7. Then, the molten material present in the spout 7 solidifies, and the outflow of the molten material as described above is stopped.

During the waste melting process as described above, the gas generated from the waste (gas containing radioactive particles) and the gas released from the plasma torches 21 and 23 are discharged through the exhaust port 26 (not shown). It is led to an off-gas treatment unit where it is purified.

As described above, since the present invention is provided with the guide tube 15 whose axis is directed toward the sump 6 of the furnace body, by putting the container 30 containing radioactive waste into the guide tube 15, it is possible to remove the radioactive waste. It has the advantage that the radioactive waste can be melted together with the container and reduced in volume by reaching the water reservoir 6.

Moreover, in the case of melting as described above, by putting the containers 30 containing waste into the guide tube 15 one after another, the container 30 at the lowest end is pushed downward by the containers 30 located above it. , the part of the container 30 and the waste therein to be melted in the future can be placed continuously in the tundish 6 from the lowest end without any break, which has the effect of extremely high melting efficiency.

Moreover, as described above, a plurality of containers 30 are connected to the guide tube 1.
5, so that even if gas containing radioactive particles is generated when radioactive waste is melted in the tundish basin 6, it will travel through the guide tube 15 and rise. This can be suppressed by the container 30 located above, and there is a safety feature that can suppress the risk that the operator who inserts the container into the guide tube 15 will come into contact with the gas.

[Brief explanation of the drawing]

The drawings show an embodiment of the present application, and FIG. 1 is a longitudinal sectional view of a melting furnace. 1... Furnace body, 6... Water reservoir, 15... Guide cylinder,
30... Container, 31... Melt.

Claims (1)

[Claims] 1 Above the furnace body, which has a concave sump on the top surface,
A hollow cylindrical guide tube having an inner diameter through which a container filled with radioactive waste can be inserted is arranged with its axis facing the water reservoir, and the length of the guide tube is such that the length of the guide tube is such that the container is The guide cylinder is formed to a length that allows a plurality of containers to be charged in a column, and the inclination of the axis of the guide tube is such that the lowermost container among the plurality of containers charged in the column is greater than that. A melting furnace for radioactive waste, characterized in that it is constructed at an angle that allows it to be pushed downward by a container located at the top.