KR910010218B1 - Method and device for processing radioactive waste - Google Patents

Abstract

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Description

Radioactive waste treatment method and device

1 and 2 are views for explaining a specific method of treating the radioactive waste and the apparatus according to the present invention.

1 is an overall view.

FIG. 2 is a detailed diagram of the gasification furnace in FIG. 1.

* Explanation of symbols for the main parts of the drawings

4: gasification furnace 5: bowl filling layer part

6: filter chamber part 9: drive motor

10: rotating shaft 11: stirring blade

12: ball 15: nitrogen gas supply port

21 filter 30 contact combustion afterburner

The present invention relates to a method for treating a radioactive waste and a device therefor, in particular, a main component such as a contaminated waste liquid generated in a nuclear power plant or the like, a waste liquid contaminated with radioactivity containing water or some organic matter and ionic radioactive substances, that is, a liquid It is suitable for use in the treatment of waste.

Conventionally, for example, in a reactor primary system of a nuclear power plant, radioactive corrosion products adhere to piping in a system by long-term operation, and workability during work such as inspection and repair by radiation emitted from these corrosion products is ensured. It worsens to the extreme and becomes a driving problem.

On the contrary, various research and development have been carried out in the past, and treatment means for dissolving and removing corrosion products adhering in pipes by chemical detergents (organic substances, etc.) have been developed.

On the other hand, a conventional treatment facility is provided with a concentrator for concentrating liquid waste and an incinerator for incineration of holding bodies.

However, this means that the liquid waste generated by the treatment means described above

(a) It is large.

(b) Radioactive contamination is high.

(c) It contains the detergent made from organic substance, etc.

As there is such a property

(a) There is a high risk of exposure to maintenance and repair due to high radioactive contamination of the entire treatment plant.

(b) Detergents may cause corrosion, etc., during operation of the concentrator, which may stop the processing of liquid wastes containing no other organic matter.

Has a problem.

In order to achieve the above object, the radioactive waste treatment method of the present invention

(a) pyrolysis and / or gasification of organic matter contained in radioactive contaminated waste in an inert atmosphere;

(b) at least a step of filtrating and filtering the gas and / or gasified organic matter by the pyrolysis, and

and (c) a step of burning and burning the gas obtained by pyrolysis and / or gasification of organic matter by catalytic combustion. In addition, the radioactive waste treatment apparatus according to the present invention

(a) a filling part which mechanically stirs the filled ceramic bowl and thermally decomposes and / or gasifies organic matter contained in the radioactively contaminated waste supplied on the filled bowl, and (ii) A reaction chamber including a filter chamber portion having a filter for filtering and dusting at least the gas obtained by pyrolysis and / or gasified organic matter from the bowl packed layer portion;

(b) A contact burner type afterburner is burned by burning the gas and / or gasified organic substance by pyrolysis filtered and filtered by the filter of the filter chamber part.

The organic matter in the radioactive contaminated waste is pyrolyzed and / or gasified and filtered out and then burned and incinerated by catalytic combustion.

Next, a description will be given of a method of treating radioactive waste according to the present invention and a specific embodiment of the apparatus with reference to the drawings.

For example, the liquid waste containing the chemical detergent and the corrosion product generated by the detergent treatment of the radioactive corrosion product in the piping of the reactor primary system of the nuclear power plant with the chemical detergent containing the organic substance or the like is supplied to the supply tank (1). Once put in. This supply tank 1 has a rotary blade 2 which is rotated by the motor M, and by this rotary blade 2 the liquid liquor waste is stirred and homogenized. This homogenized liquid waste is supplied from the lower part of the said supply tank 1 to the gasifier 4 which is one kind of reaction furnace by the supply pump 3.

Next, the gasifier 4 will be described in detail with reference to FIG.

The gasifier 4 has a bowl filling part 5 at the top and a filter chamber part 6 at the bottom, and at the same time, the bowl filling layer part 5 and the filter chamber part 6 have a porous plate 7. It is spoken to communicate through.

The bowl filling layer 5 is constructed by placing a cylindrical body 8 having a diameter of, for example, 400 mm and a height of 500 mm, and the drive provided on the bowl filling part 5 at the shaft center of the cylindrical body 8. The rotating shaft 10 which rotates at low speed (about 1 rpm) is formed by the motor M9. In the main part of the rotating shaft 10, the stirring blades 11 having spiral blades are formed such that the outer edge is located close to the inner circumferential surface of the cylindrical body 8, and the inner edge is formed between the rotating shaft 10. It is formed by being attached to the rotating shaft 10 through the support body which is not. In other words, in the cylindrical filling layer 5, a ceramic small diameter bowl 12 is deposited and filled in the cylindrical body 8. In addition, an outer heater 13 is formed on the outer circumferential portion of the cylindrical body 8 for heating the inside of the cylindrical body 8 including the bowl 12 and the like to a temperature at which the organic substance is completely pyrolyzed and / or gasified. It is. And 14 is an inlet for injecting the liquid liquor waste onto the bowl 12, which is stirred and deposited by the stirring blade 11, as shown in FIG. 15 is a nitrogen gas supply port for supplying nitrogen gas, which is one kind of inert gas, into the cylindrical body 8 in order to pyrolyze and / or gasify organic matter in the liquid waste in an inert atmosphere.

As shown in FIG. 2, the filter chamber part 6 has a diameter of, for example, a cylindrical outer cylinder 16 having a diameter of 900 mm and a downward side of the cylindrical body 8, and the bowl ( The upper layer space portion 18 is formed by an internal and external double structure by a gradually narrowing cylindrical outer cylinder 17 communicating with the cylindrical body 8 through the porous plate 7 which prevents the fall of 12). Formed. Further, below the outer cylinder 16, an organic substance in the liquid waste is pyrolyzed and / or gasified, and a conical cylinder 19 having an inclined surface is protruded so that the discharge of the inorganic substance after moisture evaporates is improved. The space part 20 is formed.

In the annular space between the outer cylinder 16 and the inner cylinder 17 in the upper space portion 18, a porous example of a plurality of user cylinders (only one is shown in the drawing) is present. For example, the sintered metal or ceramic filter 21 is disposed so as to fall down the user portion 22 at a predetermined interval so as to conform to the annular space. The openings 23 of these filters 21 communicate with the gas outlet 25 via the gas discharge passage 24. Further, at the lower portion of the conical cylinder 19, a dumper 26 for taking out the inorganic material to the hopper is formed. In the outer peripheral portion of each of the outer cylinder 16 and the conical cylinder 19, the upper layer space so as to prevent the water evaporated in the bowl-filled layer 5, and also the gas and / or gasified organic matter produced by pyrolysis to liquefy. An external heater 27 is formed to maintain the portion 18 and the lower layer space portion 20 above a predetermined temperature. And 28 is a countercurrent washing nitrogen gas supply pipe for supplying nitrogen gas for performing countercurrent washing of the filter 21.

On the outer circumference of the outer heaters 13 and 17, a heat insulating layer 29 made of a heat insulating material is formed.

The gas generated in the bowl-filled layer 5 is filtered out by the filter 21 of the filter chamber 6 together with the radioactive dust (dust), and then the gas discharge passage 24 and the gas outlet 25 Is discharged from the gasifier (4) through. This exhaust gas is mostly water vapor, and has a very low calorific value containing only a small amount of pyrolysis gas and / or evaporated organic gas generated by decomposition of organic matter contained in the liquid waste, and is a secondary combustion burner. If it does not support with fuel (for example, propane), it cannot burn stably. This exhaust gas is supplied to the catalytic combustion burner 30 in FIG. This contact combustion type afterburner 30 is, for example, a honeycomb catalyst 31 which supports a catalyst noble metal (platinum, rhodium, palladium, etc.) through active alumina (γ-alumina) on the outer surface of a ceramic honeycomb structure. By the honeycomb catalyst 31, the exhaust gas is stably combusted. Therefore, since the organic components in the exhaust gas are burned and incinerated, the exhaust gas is a clean gas containing no organic matter.

The clean gas is supplied to the condenser 32 to remove moisture by condensation. The exhaust gas from which the moisture is removed is mixed with the air heated by the heater 33 to exhaust the high performance particulate removal (HEPA) filter 34 and the exhaust gas from the gasifier 4 by exhaust gas blower ( 35 is discharged to the building ventilation air conditioning system 36 or the exhaust pipe. Then, the plurality of water vapors by the condenser 32 is discharged to the waste liquid treatment system. The supply of heated air to the exhaust gas from which the above-mentioned moisture has been removed is for preventing the remaining moisture from adhering to the high performance fine particle removal filter 34.

Since gas and / or gasified organic matter by pyrolysis before being incinerated by combustion are filtered out, the radioactive dust from the waste is not scattered in the exhaust gas system, thereby improving work during maintenance and repair of the exhaust gas system.

In addition, organic matter in the waste is stably decomposed and incinerated by pyrolysis or the like and burned, and the reduction treatment is performed.

Claims (3)

(a) pyrolyzing and / or gasifying organic matter contained in radioactive waste in an inert atmosphere, (b) filtrating and dedusting at least the gas and / or gasified organic matter resulting from the pyrolysis, and (c) And a step of burning and incineration the gas and / or gasified organic matter by the pyrolysis-filtered pyrolysis by catalytic combustion. (a) (i) a bowl-filled layer portion for mechanically stirring the filled ceramic bowl and thermally decomposing and / or gasifying organic matter contained in the radioactively contaminated waste supplied on the packed bowl, and (ii) A reaction chamber including a filter chamber portion having a filter for filtering and filtering at least the gas by pyrolysis and / or gasified organic matter from the bowl packed layer portion, and (b) the pyrolysis filtered and filtered by a filter of the filter chamber portion. An apparatus for treating radioactive waste, comprising an afterburner of a catalytic combustion type that burns and incinerates gas and / or gasified organic matter. The radioactive waste treatment apparatus according to claim 2, wherein the catalytically burned afterburner is a honeycomb catalytic afterburner.

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