JPS62148896A - Method and device for melting 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] The present invention relates to a microwave melting method and apparatus for melting radioactive waste (incineration ash) after incineration using microwaves.

[Conventional technology] Radioactive waste generated from nuclear power plants, etc. is roughly divided into three types: gas, liquid, and solid, and the strength of radioactivity is classified into high, medium, and extremely low levels. Ru.

Conventionally, combustible materials among low-level solid wastes have been incinerated, and then the ashes have been stored in drums.

However, with the increase in the amount of solid waste mentioned above, a large amount of ash is generated after incineration, and the amount stored is increasing year by year.
The above-described processing has its own limitations.

Therefore, it is possible to treat the solid waste (incineration ash) using microwaves, for example, as disclosed in Japanese Patent Application Laid-Open No. 55-143380.
It is disclosed in the publication number etc.

The radioactive waste processed by these microwave melting devices is so-called incinerated ash, which is obtained by incinerating radioactive waste discharged from nuclear power plants and the like.

In these methods, the incinerated ash stored in the drum can is supplied to the microwave melting device by some method. Microwaves generated by a microwave generator are supplied to the furnace body via a waveguide to melt the incinerated ash within the retort, and after the melting is complete, the retort is separated from the furnace body.

[Problem that the invention seeks to solve]

However, the method described above requires special means for its maintenance and management, and has the drawback of being time-consuming and time-consuming.

In addition, it only discloses the means for controlling the microwaves generated by the microwave generator, controlling the amount of incinerated ash supplied, monitoring the melting situation, etc., and does not disclose anything about the correlation between these. . Therefore, although each part could be controlled, there was nothing to control the entire system.

[Purpose of the invention]

The present invention was made to solve such conventional problems, and its purpose is to efficiently melt radioactive waste (incineration ash) carried into a treatment plant in the retort I. Provided is a method and apparatus for melting radioactive waste that can efficiently melt incinerated ash in a retort by supplying microwaves, supplying the necessary amount of incinerated ash, and matching microwaves within a waveguide. It is something to do.

[Means for solving problems]

In the method for melting radioactive waste according to the present invention, microwaves generated by a microwave generator are guided into a furnace body through a waveguide, and are continuously supplied into a retort connected to the lower part of the furnace body. In the method of melting radioactive waste,
The process involves installing a retort at the bottom of the furnace body, guiding the microwaves generated by the microwave generator into a waveguide, increasing or decreasing the microwave output in the waveguide with a power monitor, and adjusting the magnetic field with an EH tuner. , the step of supplying microwaves to the furnace body while adjusting the electric field to combine with radioactive waste, preventing dust from entering with at least one quartz plate, and preventing backflow of radioactivity; The process of continuously feeding waste and monitoring the entire molten metal surface in the retort using a wide-angle non-contact thermometer located at the top of the furnace body, and determining the ratio of the molten surface to the unmelted surface in the retort. The process involves controlling the amount of radioactive waste sent based on the average temperature of the entire hot water surface, and monitoring the inner wall of the retort using a radiation thermometer and feedstop thermometer installed in the furnace body to ensure that the hot water level reaches a predetermined level. The process of stopping the supply of radioactive waste when the melted radioactive waste in the retort is completed, the process of supplying a glass forming material on top of the melted radioactive waste in the retort to contain the radioactivity, and the process of containing the radioactive waste in the retort with glass is completed. , and the step of stopping the supply of microwaves.

Further, the microwave melting device according to the present invention includes a microwave generator, a waveguide for guiding the microwaves generated by the microwave generator, a furnace body connected to the waveguide, and a furnace body. The microwave melting equipment consists of a radioactive waste supply device that continuously supplies radioactive waste to the furnace body, and a glove box that is installed at the bottom of the furnace body and connects and separates the retort from the bottom of the furnace body. A power monitor and an EH tuner installed in the waveguide, and a wide-angle non-contact thermometer installed on the top of the furnace body to monitor the temperature of the entire molten metal surface in the retort and control the amount of radioactive waste fed. , an ITV installed at the top of the furnace body to monitor the arc and gas combustion status of the furnace body, an exhaust system installed in the furnace body to discharge exhaust gas from inside the furnace body, and an ITV installed in the furnace body to monitor the arc and gas combustion status of the furnace body, an exhaust system installed in the furnace body to discharge exhaust gas from inside the furnace body, and a glass forming material supply device for supplying a glass forming material to contain radioactivity after melting radioactive waste; an arc sensor provided in the furnace body to monitor arc within the furnace body; It is equipped with a radiation thermometer and feedstop thermometer that monitors the temperature of the inner wall of the retort and issues a command to stop the supply of radioactive waste when the level of molten radioactive waste reaches a predetermined level.

[Action of the invention]

In the present invention, the output of the microwaves generated by the microwave generator can be monitored by a power monitor installed in the waveguide, and the amplitude of the magnetic field and electric field can be adjusted by the EH tuner to control the melting material. Can be combined with Moreover, since the waveguide is provided with a quartz plate, microwaves can be supplied to the furnace main body while preventing backflow of radioactivity. Furthermore, in the furnace body, the temperature of the melting surface in the retort is monitored using a wide-angle non-contact thermometer to control the amount of incinerated ash to be fed, so that incinerated ash is accurately supplied.

Furthermore, the furnace itself uses a radiation thermometer and feedstop thermometer to monitor whether the melting surface of the incinerated ash has reached a predetermined level and then stops the supply of incinerated ash, ensuring that the ash is completely melted. This allows the incineration ash to be completely melted.

Further, after melting, a glass forming material is supplied to cover the melted incineration ash, so there is no leakage of radioactivity.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

In the figure, l is a microwave generator, 2 is a waveguide attached to this microwave generator 1, 3 is a power monitor installed in this waveguide 2, an output detector 4 and a reflected wave detector. 5 to monitor the microwave output. 6 is an EH tuner, which has an electric field adjuster 7 and a magnetic field adjuster 8, adjusts the amplitude of the magnetic field and the electric field, and adjusts the amplitudes of the magnetic field and the electric field to match the non-melted material (incinerated ash). Reference numeral 9 denotes two quartz plates provided in the waveguide 3, which allow microwaves to pass through but not dust, and prevent backflow of radioactivity. Air at a predetermined pressure is constantly sent to the space 34 between the quartz plates 9, and an alarm device 3 warns of the pressure drop when the quartz plates 9 are damaged to prevent radioactivity from flowing back.
5 is a provision. 10 is a furnace body, to which a waveguide 2 is connected. 1) is a wide-angle non-contact thermometer installed at the top of the furnace body 10, which monitors the temperature of the melting surface within the retort 27 and controls the amount of incinerated ash to be fed. 12 is an ITV, which monitors the arc and gas combustion conditions within the furnace body 10. In order to prevent the adhesion of ash by blowing air to the monitoring window where the ITV 12 is installed, air is constantly supplied so that the situation inside the furnace body 10 can be accurately grasped. 13 is an exhaust device provided in the furnace body 10, which includes a hack filter 14, a HEPA filter 15. Exhaust blower 16
The exhaust gas inside the furnace body 1o is discharged while preventing the outflow of radioactivity. 17 is a glass forming material supply device provided in the furnace body 10, and after the incineration ash has been completely melted in the retort 27, a glass forming material is supplied thereon to seal the incineration ash so that it does not leak. It is composed of 18
19 is the arc sensor provided in the furnace body 10, and 19 is the furnace body 10.
It is a radiation thermometer and feedstop thermometer installed in
It is configured to monitor the condition of the inner wall of the retort 27 and issue a command to stop the supply of incinerated ash when the molten surface of the incinerated ash reaches a predetermined level. 20 is an incineration ash supply device provided in the furnace body 10, which includes a device 22 for taking out the incineration ash sent in the drum can 21, and a ceramic filter 23 for adsorbing and separating the incineration ash that is air-transported after being taken out. , a hopper 24 for receiving and taking the incinerated ash separated from the ceramic filter 23 by a separation plate, and a screw feeder 25. 26 is a glove box provided at the lower part of the furnace main body IO, a retort lifting device 28 that connects and separates the retort 27 for receiving and receiving incinerated ash from the lower part of the furnace main body 10, and a retort that packs the retort 27 into the drum can 32. It is composed of a moving device 30 and a turntable 31 for carrying out the retort 27 packed in the drum can 32.

Next, this example will be explained according to its processing steps.

First, the retort 27 is raised by the lifting device 28 and connected to the lower part of the furnace body 10. This connection is made via a choke structure 36 to prevent microwave leakage.

Next, incineration ash is continuously supplied to the retort 27 from the screw feeder 25. This supply is carried out by pneumatically transporting incinerated ash, which has been packed into a drum can 21 and carried in, into a ceramic filter 23 in an incinerated ash supplying device 20.
It is adjusted so that it can be adsorbed and separated, stored in a hopper 24, and supplied to the furnace main body 10 by a screw feeder 25, so that it can be carried out according to instructions from a control device (not shown) or an operator. At this time, since the incineration ash has a high accuracy of separation efficiency of 99.99% or more between air and granular powder by the ceramic filter 23, there is no risk of radioactivity leaking from the air that is separated and exhausted to the outside.

After this incineration ash is supplied, the microwave generator 1 is driven to generate microwaves, and the microwaves are supplied to the furnace body 10 via the waveguide 2. At that time, the power monitor 3 monitors whether the output of the microwave is a predetermined value, and if it is not the predetermined value, the output of the microwave generator 1 is adjusted via a control device (not shown). . Also, E
The H tuner 6 adjusts the amplitude of the microwave magnetic field and electric field to match the incinerated ash, which is the object to be treated.

In this way, the incinerated ash continuously supplied to the retort 27 is melted by microwaves. This situation is monitored by the wide-angle non-contact thermometer 1) and the ITV 12, as well as by the radiation thermometer/feedstop thermometer 19.

In this melting process, the incinerated ash is transferred to the screw feeder 2.
The melting process is carried out by continuously supplying the molten metal by 5. The surface of the molten metal in this treatment step is such that unmelted material partially covers the surface of the molten metal, which is at a high temperature of around 1200°C.

In order to completely melt the material to be melted and obtain a uniform melted material, it is necessary to maintain the state of this surface in a certain appropriate state.

Therefore, in the present invention, the temperature of the hot water surface is controlled by controlling the amount of material to be melted.

Specifically, a wide-angle non-contact thermometer 1) was provided at the upper part of the furnace body 1o, and a radiation thermometer/feedst thermometer 19 was provided inside the furnace body 1o.

A wide-angle non-contact thermometer 1) measures the average temperature of the entire hot water surface.It measures uneven hot water surface temperature as an average value, and also measures the ratio of molten surface to unmelted material over the entire hot water surface. The amount of incinerated ash sent is controlled by capturing the ash at an average temperature of

However, in the melting process, it is necessary to stop charging the material to be melted before the melt overflows from the retort 27, but in a furnace that uses microwaves as a heating source, it is necessary to insert a sensor into the furnace body 10. I can't.

Therefore, in the present invention, a radiation thermometer/feet hip thermometer 19, which is a non-contact type thermometer (radiation thermometer), is used to measure one point on the inner wall of the retort, and the hot water level reaches this measurement point. By detecting a rise in temperature, the injection of incinerated ash was stopped.

The radiation thermometer/feedstop thermometer 19 is installed in the center of the furnace body 10 so as to face diagonally downward so that the temperature at a position approximately 10 clIl downward from the flange surface 271 of the retort 27 can be measured. .

When the melt level is below the measuring point during the melting process, a temperature of 800°C or less is specified, and when the melt level rises to the measuring point, the temperature is 100°C.
The temperature rises from 0 to 1200°C. Therefore, an alarm mechanism was installed, and when the temperature at the measurement point exceeds 1000℃, the feeder 25
The ink lock is applied to the motor 251. This ink lock can then be manually released in order to proceed to the next process.

Therefore, the amount of incinerated ash supplied by the feeder 25 is controlled by the wide-angle non-contact thermometer 1), and the radiation thermometer doubles as the feet!・Retort 2 by knob thermometer 19
Directly monitor the melting situation within 7. At this time, the temperature control of the hot water surface is performed based on the sensing signal from the wide-angle non-contact thermometer 1).
1- This is done through the flow of adding incinerated ash.

When the radiation thermometer/feedstop thermometer 19 detects that the molten ash level has reached a predetermined level, the supply of the incinerated ash from the incinerated ash supply device 20 is stopped.

Next, a glass forming material is supplied from the glass forming material supplying device 17 to cover the incinerated ash with the glass forming material, and then the glass forming material is melted with microwaves to confine the radioactivity.

After that, the microwave generator 1 is stopped to stop the supply of microwaves. Then, the molten material in the retort 27 is cooled and solidified. Next, after the retort 27 is lowered by the retort lifting device 28, the retort 27 is rotated by the moving device 29 and packed into the drum can 32 placed on the retort moving device 30. After solidifying this drum can 32 with cement, the turntable 31
Export it.

Incidentally, the exhaust gas generated in the above treatment process is exhausted to the outside of the furnace main body 10 by an exhaust device 13 while preventing the leakage of radioactivity. Further, since the inside of the furnace body 10 is processed in an air or nitrogen atmosphere, there is almost no arc generation, but it is monitored by the ITVII and the arc sensor 18 in case of an unexpected situation. Moreover, in the waveguide 2, two quartz plates 9.
Air under a predetermined pressure is supplied to the space 34 defined by the quartz plate 9, and when the quartz plate 9 is damaged for some reason, the pressure drop is detected and an alarm is issued by the alarm 135, and the radiation is emitted. This prevents the ability from leaking out.

〔Effect of the invention〕

As described above, according to the present invention, (1) the melting of the incinerated ash in the retort is monitored by the radiation thermometer and feedstop thermometer, so the supply and stop of the incinerated ash can be reliably controlled.

■Since the microwave is controlled within the waveguide, it is possible to control the increase or decrease of the required microwave output. ■Radioactive thermometer and feedstop thermometer to measure the melting status in the retort.

To be monitored by wide angle non-contact radiation thermometer, ITV,
The inside of the furnace can be managed reliably. ■Since monitoring is performed reliably, the timing and amount of supply of glass forming materials can be reliably controlled. (2) After the incineration ash is melted, a glass forming material, which is a non-radioactive material, is poured onto the top of the molten material and melted, which has the advantage of ensuring the containment of radioactive materials.

[Brief explanation of drawings]

The drawings are explanatory diagrams showing one embodiment of the present invention. ■...Microwave generator, 2...Waveguide, 3...
・Power monitor, 6...EH tuner, 9...quartz plate, 10...furnace body, 1)...wide-angle non-contact thermometer,
12... ITV, 17... Glass forming material supply device,
19... Radiation thermometer and feedstop thermometer, 20
...Incineration ash supply device (radioactive waste supply device), 25
... Feeder, 27... Retort.

Claims (2)

[Claims] (1) A method in which microwaves generated by a microwave generator are guided into the furnace body through a waveguide to melt radioactive waste that is continuously supplied into a retort connected to the bottom of the furnace body. The process involves attaching a retort to the lower part of the furnace body, guiding the microwaves generated by the microwave generator to a waveguide, increasing and decreasing the microwave output using a power monitor in the waveguide, and performing EH. A process of adjusting the magnetic field and electric field using a tuner to match the radioactive waste, and supplying microwaves to the furnace body while preventing dust from entering and backflow of radioactivity using at least one quartz plate, and a retort. The entire molten metal surface in the retort is monitored by a wide-angle non-contact thermometer located at the top of the furnace body, and the ratio of molten surface to unmelted surface in the retort is measured. The process involves controlling the feed rate of radioactive waste based on the average temperature of the entire hot water surface determined by A process of stopping the supply of radioactive waste when the level reaches the level, a process of supplying a glass forming material on top of the melted radioactive waste in the retort to contain the radioactivity, and A method for melting radioactive waste, comprising the step of stopping the supply of microwaves after completion of containment. (2) A microwave generator, a waveguide that guides the microwaves generated by the microwave generator, a furnace body connected to the waveguide, and a continuous supply of radioactive waste to the furnace body. In the microwave melting device, which is composed of a radioactive waste supply device that provides radioactive waste, and a glove box that is installed at the bottom of the furnace body and connects and separates the retort to the bottom of the furnace body, the power provided in the waveguide is monitor, EH tuner, and a wide-angle non-contact thermometer that is installed at the top of the furnace body to monitor the temperature of the entire molten metal surface in the retort and control the amount of radioactive waste sent. , ITV that monitors the arc and gas combustion status of the furnace body
, an exhaust device installed in the furnace body to exhaust exhaust gas from inside the furnace body, and a glass forming material installed in the furnace body to supply a glass forming material that confines radioactivity after the radioactive waste is melted in the retort. A supply device, an arc sensor installed in the furnace body to monitor the arc within the furnace body, and an arc sensor installed in the furnace body to monitor the temperature of the inner wall of the retort to ensure that the molten metal level of radioactive waste reaches a predetermined level. A microwave melting device characterized by being equipped with a radiation thermometer and feedstop thermometer that issues a command to stop the supply of radioactive waste.