JPS5834800B2 - How to treat the Hepafilter used - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention applies to hepa
The present invention relates to a method for reducing the volume of an EPA filter.

Facilities that handle radioactive materials, such as nuclear power plants and nuclear fuel reprocessing plants, use filters called HEPA filters, which are made of alternating layers of glass fiber boards and asbestos corrugated sheets, as the final step in treating exhaust gas containing radioactive materials. Filtration takes place.

The amount of Hepa filters used has increased with the progress of the atomic crab industry, and the amount of used Hepa filters being stored has been increasing, and the disposal of this has become a problem.

Conventional processing methods for Hepa filters include the crushing method (Japanese Patent Application Laid-Open No. 51-31400, etc.) and the cutting method (Japanese Patent Application Laid-open No. 51-1870, etc.).
Volume reduction processing methods such as I couldn't say yes.

Furthermore, an asphalt solidification method (Japanese Patent Application Laid-Open No. 52-50500) has been proposed as a final disposal method, but this also has unresolved problems in terms of volume reduction.

The present invention has been made with the aim of solving the above-mentioned problems by reducing the volume of a used hepafilter contaminated with radioactive substances as much as possible and making it possible to store it stably for a long period of time.The present invention is characterized by: A used Hepa filter contaminated with radioactive materials used at a nuclear facility was dismantled and separated into the filter material, frame and accessories, and the filter material was calcined at over 800℃ to remove flammable components. Afterwards, they are melted and solidified in a microwave irradiation furnace, while combustible materials such as wood for the frame and accessories are incinerated, and the incinerated ash is melted and solidified together with the above-mentioned calcined materials in a microwave irradiation furnace. The main part is that it is melted and solidified in a metal melting furnace.

As shown in the drawing, the Hepa filter to be treated in the present invention is a glass fiber board 1-2 and an asbestos corrugated board 1-1.
A filter material composed of alternately laminated layers is housed in a frame 1-3 made of wood or metal (iron, etc.), and an inlet for the gas to be treated is provided on both sides of the frame 1-3. , a metal (made) pipe 1-4 serving as an outlet is attached.

As described above, the hepafilter is composed of a refractory material, a combustible material such as wood, and metal, and it is not appropriate to process these together during the melt-solidification process.

Therefore, in the present invention, the Hepa filter is first disassembled and the filter material, which is a fire-resistant material, and the frame and accessories (pipes, nails, etc.) are separated and processed.

In the present invention, the separated filter material is melted and solidified using a dielectric heating method using microwave irradiation, but a problem arose when this method was applied to the above-mentioned filter material.

In other words, this filter material, especially the asbestos corrugated plate, is made into a corrugated plate shape using a large amount of organic adhesive, so if the filter material is crushed as it is, it will be difficult to crush it, and at the same time, if it is fed to a microwave irradiation furnace, The organic adhesive starts to burn before the glass fibers and asbestos melt, and the resulting smoke builds up inside the furnace.This smoke induces a discharge phenomenon within the furnace, and the microwave irradiation efficiency is extremely reduced.
This makes melt processing impossible.

In order to solve this problem, the present invention investigated a method in which the filter material is calcined prior to being irradiated with microwaves.

In other words, heat the filter material at 700 to 1000°C for 15 to 30 minutes.
The material was heated and burned in air for 120 minutes to investigate changes in its composition, and the obtained calcined material was melted in a microwave irradiation furnace.

The results are shown in Table 1. As is known from Table 1,
When the filter material was calcined at 800° C. or higher, no discharge phenomenon due to smoke was observed during microwave irradiation, and the material was in a good melted state.

For this reason, in the present invention, when melting and solidifying the filter material by microwave irradiation, it is necessary to
It is known that it is necessary to remove combustible substances from the filter material by calcining it at a temperature of C or higher.

Additionally, calcined materials have the advantage of being easy to crush.

Next, an embodiment of the present invention will be described according to the flow sheet shown in FIG.

The wooden frame hepa filter 1 as shown in FIG. The calcined material (C0,03
) is then processed into a powder with a particle size of 3 or less in a crusher 7,
It was supplied to the microwave irradiation furnace 9.

On the other hand, the wooden frame 4 was cut into pieces and then incinerated in an incinerator 8, and the incinerated ash was supplied to a microwave irradiation furnace 9 together with the calcined material.

The amount supplied to the microwave irradiation furnace is 100g of calcined material and 27g of incinerated ash, which are supplied to the crucible and the output is 5kW.
The melting process is completed in 5 minutes, and then it is cooled to form a solidified product
And so.

This solidified body 10 is stored 14 after decontamination 13.

On the other hand, the metal (iron) of the pipes and nails that are accessories are ESR.
The ingots are melted in a melting furnace 11 of the same method, and become ingots 12, which are decontaminated (13) and stored (14).

In addition, in this treatment method, it is also possible to treat plastics such as PVC other than Hepafilter, and in the case of treating plastics, the plastics are acid-digested and the acid-digested residual fragrance is mixed with the filter material and heated to 800℃. After calcining in the above manner to remove 803 minutes contained in the residual aroma, the product is supplied to a microwave irradiation furnace.

As described above, according to the present invention, it is possible to carry out full-scale and comprehensive volume reduction treatment for used puff filters, for which treatment for long-term storage has not been established in the past, and to enable long-term stable storage. It will pave the way for

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the appearance of a Hepa filter, and FIG. 2 is a flow sheet of the method of the present invention. 1: Hepa filter, 1-2 glass fiberboard, 1-1:
Asbestos corrugated plate, 1-3: Frame, 1-4: Pipe, 3:
Filter material, 4: Wooden frame, 5: Metal, 6: Calciner,
7: Pulverizer, 8: Incinerator, 9: Micro; skin irradiation furnace, 1
0: Solidified body, 11: ESR melting furnace, 12: Ingot,
13: Decontamination, 14: Storage.

Claims (1)

[Claims] 1. A used hepa filter contaminated with radioactive materials used in a nuclear power facility is disassembled and separated into a filter material, a frame body, and accessories, and the filter st so. After calcining at temperatures above ℃ to remove combustible materials, they are melted and solidified in a microwave irradiation furnace.For frames and accessories, combustible materials such as wood are incinerated and the incinerated ash is used as the above-mentioned calcined material. A method for processing a used hepa filter, characterized in that the metal part is melted and solidified in a microwave irradiation furnace, and the metal part is melted and solidified in a metal melting furnace.