JPH09211164A - Oxidation / reduction furnace for nuclear fuel regeneration - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To improve reliability by completely sealing the powder-contacting part from the loading of the processed material to the removal after processing, and to prevent the contamination by placing the furnace body part outside the glove box. , Improve maintainability. SOLUTION: One half of the rotary drum 1 for containing nuclear fuel scrap is narrowed in a taper shape, and its extension end 9 is connected to a connecting portion 6.
Is connected to the side part of the connection part 6 so that the scrap input part 4 is connected to the upper part of the connection part 6 and the extraction part 5 is connected to the lower part of the connection part 6 in an openable and closable manner.
Are connected to the connecting portion 6, and the connecting portion 6, the charging portion 4, and the extracting portion 5 are housed in a glove box 18 that blocks outside air, and the rotating drum 1, the rotation driving device 2, the heater portion 3, and The tilting device 8 is arranged outside the glove box.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear fuel regenerating oxidation / reduction furnace for regenerating nuclear fuel scrap produced in the process of producing nuclear fuel pellets.

[0002]

2. Description of the Related Art In the process of manufacturing nuclear fuel pellets,
Process scraps of radioactive materials such as uranium oxide (defective products,
Since polishing dust, dust collecting powder, etc.) are generated, oxidation treatment and reduction treatment are performed in a high temperature furnace in order to reuse them. In this equipment, it is the most important issue to minimize the leakage of processed materials (scrap) into the factory room and the scattering to the exhaust system due to the peculiarity of handling radioactive materials (to prevent exposure to radiation). In addition to automation and improvement of reliability, ease of maintenance is also an important issue. As these oxidation / reduction furnaces for nuclear fuel regeneration,
Conventionally, there are a container transport system, a continuous rotary kiln system, a batch rotary kiln system, and the like.

The container transfer system is a system in which scrap is transferred into a container such as a sintering dish, and the vertical batch processing furnace as shown in FIG. 6 and a horizontal batch processing furnace (not shown) in which the scrap is laid down are provided. Alternatively, there is a tunnel-type continuous furnace that can continuously feed the sintering dish. In each of these processing furnaces, the container has to be an open type in order to react the atmosphere in the furnace with the material to be processed, and there is a risk of inherent scattering. Therefore, it is necessary to provide a sealed glove box to prevent leakage into the work room and carry it inside. Therefore, all the devices, parts, etc. installed in the glove box are radioactively contaminated, which makes maintenance work difficult.
By the way, in terms of processing capacity, the thickness of the processed material to be put in the container can be only a small amount in order to sufficiently carry out the reaction with the oxidizing and reducing gas, so a wider input area is required to secure the same processing capacity. Is required, and there is a disadvantage that the equipment becomes larger than other models.

On the other hand, in general, in the oxidation and reduction treatments, it is desirable to stir the treated material in order to improve the reaction between the treated material and the atmospheric gas. For this reason, the rotary kiln system is often adopted. Normally, the continuous rotary kiln is
As shown in the figure, the processed material is placed in a cylindrical rotating cylinder and rotated.
It is a continuous type processing equipment that feeds from the raw material input side to the discharge side by the inclination of the rotary drum or internal blades. Therefore, when performing the oxidation and reduction processes, two rotary drums are required because the atmospheric gases are different. That is, in this processing facility, since a high-temperature processed material passes through the outlet of the oxidation rotary kiln and the inlet of the reduction rotary kiln, a heat-resistant sealing structure or a cooling structure for different atmospheric gases in the oxidation / reduction partition is required.

Further, although there are rotary retort type and horizontal retort type (not shown) also in the batch type rotary kiln system, all of them are closed, automated, reliable, and maintained with respect to a method of charging and discharging raw materials and an exhaust system. There is a difficulty in the ease of. Incidentally, the rotary retort type has the following problems. ○ It is difficult to open and close the valve automatically because the rotating cylinder is equipped with a valve for loading and discharging the processed material and the valve itself rotates with the rotating cylinder. ○ The furnace body has a large inclination when loading and unloading the processed material, making it difficult to seal the glove box. Therefore,
Since the whole furnace body is put in the glove box, the whole furnace body is contaminated, which is disadvantageous for maintenance. Also,
The horizontal retort type has the following problems. -Since the door for loading and unloading the processed material is attached to the rotating drum, and the door itself rotates with the rotating drum, it is difficult to open and close the door automatically. ○ The door will be opened when the processed material is put in or taken out, and it is necessary to secure the negative pressure control wind speed in the furnace at the opening. At the time of discharging the processed material, the processed powder is lifted by the internal blade and dropped on the receiving feeder, so that the fine powder rises. Therefore, the floating powder in the furnace is also disadvantageous because it easily flows into the exhaust system.

[0006]

SUMMARY OF THE INVENTION The present invention addresses the above situation, and in the above-mentioned fuel scrap oxidation / reduction equipment, the powder-contact portion is completely sealed from the input of the processed material to the removal after the processing. In addition to improving reliability, we also provide equipment that is easy to maintain.

[0007]

That is, the features of the oxidation / reduction furnace for regenerating nuclear fuel of the present invention which meet the above-mentioned object are that a tubular rotating cylinder is provided horizontally and the rotating cylinder is centered around its axis. A drive device for rotating, an inclining device for inclining the rotating drum, and a heater portion arranged around the rotating drum,
An input part for inputting nuclear fuel scrap to the rotary cylinder, an extraction part for extracting nuclear fuel scrap from the rotary cylinder, a connecting part for connecting the input part and the extraction part to the rotary cylinder, and an atmospheric gas for supplying the rotary cylinder. And a supply / exhaust pipe for exhausting, one half of the rotary drum is tapered and narrowed,
The extension end portion is rotatably connected to the side portion of the connecting portion, the input portion is connected to the upper portion of the connecting portion, and the outlet portion is connected to the lower portion so as to be openable and closable. Connected to the connecting part, the connecting part, the charging part, and the extracting part are housed in a glove box that shuts off the outside air, and the rotating drum, drive device, heater part, and tilting device are arranged outside the glove box. It is in the place where it was set up.

[0008]

In the oxidation / reduction furnace of the present invention, only the portion related to the leakage of the processed material is concentrated in the connecting portion and housed in the glove box, while the rotating drum, the driving device, the heater portion, and the tilting device. A part irrelevant to leakage such as the above is arranged outside the glove box, and the powder contact part is completely sealed from the input of the processed product to the removal after the processing to improve reliability, and the rotating cylinder etc. It is possible to arrange the furnace body outside the glove box to prevent its contamination and improve maintainability.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the oxidation / regeneration for nuclear fuel regeneration of an embodiment of the present invention.
FIG. 2 is a side view showing the reduction furnace, FIG. 2 is a plan view of the same, and FIG. 3 is an enlarged cross-sectional view showing the vicinity of the connecting portion of the embodiment. The oxidation / reduction furnace of the above-described embodiment has a cylindrical rotary drum 1 horizontally installed as shown in FIG. 1, a drive unit 2 for rotating the rotary drum 1 about its axis, and the rotary drum 1 vertically. Inclining device 8 for inclining
A heater part 3 arranged around the rotary cylinder 1, a charging part 4 for charging the nuclear fuel scrap N into the rotary cylinder 1, and a take-out part 5 for removing the processed scrap N from the rotary cylinder 1.
And a connecting portion 6 for connecting the input portion 4 and the take-out portion 5 to the rotary drum 1, an air supply pipe X and an exhaust pipe Y for supplying various atmospheric gases to the rotary drum 1, and ventilation pipes 7a and 7b. There is.

The front half of the rotary drum 1 on the left side in the drawing is tapered and narrowed down, and its extending end portion 9 is formed in a pipe shape as shown in FIG. 3 and is rotatably connected to the connecting portion 6. Has been done. Further, the rear end 10 of the rotary drum 1 is formed in a cylindrical shape with its tip closed, and as shown in FIG. 3, both ends of a heater box 11 surrounding the heater part 3 together with the base of the extended end part 9 are formed. The bearing 12 is rotatably supported at a plurality of positions.

The drive device 2 is provided with a motor and drives the rotary drum 1 pivotally supported as described above to rotate via a chain or the like. Further, the tilting device 8 is, as shown in FIG.
An inclined fulcrum portion 13 that pivotally supports the rotary drum 1 near the base of the extended end portion 9 thereof via the heater box 11 and a jack-shaped cylinder portion 14 that supports the heater box 11 from below are provided. The cylinder portion 14 allows the rotary drum 1 to be tilted vertically from the horizontal state.

On the other hand, as shown in FIG. 3, the input part 4 is connected to the upper part of a box-shaped connecting part 6 and the take-out part 5 is connected to the lower part of the connecting part 6 by a switching valve 15 so as to be openable and closable. Has been. The input unit 4 and the output unit 5 are
Each has a funnel-shaped supply container 16 and a take-out container 17, and the supply container 16 is fixed to an upper step portion of a glove box 18 described later via a bellows 19. The take-out container 17 is fixed to the lower part of the glove box 18,
It is connected to the connecting portion 6 via another bellows 19.

Further, the ventilation pipe is provided with a supply 7a and a discharge 7b to ensure escape of gas at the time of scrap loading and unloading. Further, the air supply pipe X communicates with the rotary drum 1 by partially penetrating the upper portion of the connecting portion 6 as shown in FIG. Further, the exhaust pipe Y passes through the axis from the rear end 10 of the rotary drum 1, passes through the switching valve 15, and is pulled out to the outside. An exhaust hole 20 is formed through the exhaust pipe Y,
By supplying the gas from the air supply pipe X, the gas inside the rotary drum 1 is exchanged from the exhaust hole 20 through the exhaust pipe Y. The exhaust pipe Y is rotatably supported at the rear end 10 of the rotary cylinder 1 so as not to rotate together with the rotary cylinder 1.

Finally, the glove box 18 is made of an airtight box, which accommodates the connecting portion 6, the charging portion 4, and the discharging portion 5 as shown in FIG.
As shown in FIG. 3, the extended end portion 9 of the rotary body portion 1 is penetrated together with the outer cylinder portion 21. Further, a bellows-shaped partition film 22 is doubled on the outer periphery of the outer cylinder portion 21. The rotating body 1, the driving device 2, the heater unit 3, and the tilting device 8 are arranged outside the glove box 18.

However, in the method of using the oxidation / reduction furnace of the above embodiment, first, scrap is put in the closed supply container 16 and the rotary cylinder 1 is tilted by the tilting device 8 to form the tilt fulcrum portion 13 as shown in FIG. The rear end 10 is lowered as a fulcrum.
Next, the switching valve 15 is opened, and the scrap is dropped on the rotary cylinder extension end 9. At this time, the rotary drum 1 is rotated by the drive device 2, and the scrap is sent to the back of the rotary drum 1 by this rotation and the inclination including the taper.

During the oxidation treatment and the reduction treatment, the rotary drum 1 is returned to a horizontal state as shown in FIG. 1, and the scrap is heated by the heater portion 3 through the rotary drum 1 while rotating the rotary drum 1. The atmosphere gas is switched to an oxidizing gas, an inert gas for substitution, or a reducing gas from the outside according to the purpose of treatment, enters through the air supply pipe X, and is exhausted through the exhaust pipe Y. At this time, since the air supply pipe X is connected to the connecting portion 6, it is possible to cool the connecting portion 6 which receives heat from the rotary drum 1 and the exhaust pipe Y by the air supply gas, and conversely The gas is introduced into the rotary drum 1 while obtaining heat energy through heat exchange to save energy. The exhaust atmosphere gas is cooled and exhausted.

The scrap in the rotary drum 1 is lifted in the circumferential direction by the axial groove (not shown) provided on the inner surface of the rotary drum 1 and the rotation of the rotary drum 1, and the atmosphere is agitated by repeated falling. Sufficient reaction with gas is possible. After treating with an oxidizing gas in an oxidizing atmosphere, the inert gas is once changed, the oxidizing gas in the furnace is replaced, and then the reducing gas is changed. Here, it is not necessary to cool the object to be treated and the furnace body, and a series of treatments can be continuously performed, which leads to energy saving.

After the oxidation and reduction processes are completed, the furnace heater is turned off, and indoor exhaust air is taken in through the intake port 24 by the exhaust fan 23 provided in the furnace and cooled through the rotary drum 1. After the cooling is completed, the switching valve 15 provided in the connecting portion 6 is inverted by a power unit (not shown) to close the supply and open the discharge. Then, as shown in FIG. 5, the rotary drum 1 is tilted with its rear end raised, and the oxidation / reduction treatment product of scrap is discharged while rotating the rotary drum 1. The gas in the take-out container 17 is automatically blocked by a ventilation pipe 7b to ensure a route to escape to the rotary drum 1 side in accordance with the amount of the discharged product.

The embodiment of the present invention has been described above. By scraping the first half of the rotary cylinder 1 from a shape having a step, the scrap can be reliably retained in the heat treatment section. This makes it possible to increase the throughput of scrap and shorten the furnace length. Further, the taper determines the inclination angle at the time of scrap discharge, which is advantageous in that the inclination angle is smaller than that of the stepped shape. The taper of the rotary drum 1 increases the distance between the heat treatment section and the connecting section 6 (connecting section) to facilitate heat insulation. This contributes to prevention of thermal deformation and deterioration when a resin material is used for the glove box 18. Further, the taper reduces the diameter of the bearing portion of the connecting portion 6, thereby making the furnace body compact and reducing heat conduction from the furnace body to save energy. Further, by providing the inclined fulcrum portion 13 of the rotary cylinder in the vicinity of the partition film 22 of the glove box, the deformation amount of the partition film 22 can be minimized. The safety is increased by forming the partition film 22 double. As described above, the structure of the present invention is very effective for a series of treatments in an oxidation / reduction furnace, and can also be applied to a single process as an oxidation furnace or a reduction furnace.

[0021]

As described above, according to the oxidation / reduction furnace for regenerating nuclear fuel of the present invention, one half of the rotary cylinder for accommodating the nuclear fuel scrap is constricted in a taper shape, and the extended end portion is located on the side of the connecting portion. In addition to being rotatably connected to the part, the scrap input part is connected to the upper part of the connection part, and the extraction part is connected to the lower part so as to be openable and closable, and the atmosphere gas supply / exhaust pipes are connected to the connection part. The connecting portion, the input portion, and the take-out portion are housed in a glove box that shuts off the outside air, and the rotating drum, the rotation driving device, the heater portion, and the tilting device of the rotating drum are arranged outside the glove box. While only the parts related to the leakage of the processed material are concentrated in the connecting part and stored in the glove box, the parts such as the rotating drum, the driving device, the heater part and the tilting device which are not related to the leakage are connected to the glove box. Since it is placed outside, the powder contact part is completely sealed from the loading of the processed material to the removal after processing to improve reliability, and the furnace body part such as the above-mentioned rotating drum is arranged outside the glove box to It has a remarkable effect of preventing contamination and remarkably improving maintainability.

[Brief description of drawings]

FIG. 1 is a side view showing an oxidation / reduction furnace for nuclear fuel regeneration according to an embodiment of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is an enlarged cross-sectional view showing the vicinity of a connecting portion of the embodiment.

FIG. 4 is a side view showing a state when the nuclear fuel scrap of the embodiment is loaded.

FIG. 5 is a side view showing a state during discharging.

FIG. 6 is a front view showing a conventional vertical batch processing furnace.

FIG. 7 is a side view showing a conventional rotary kiln type furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotary cylinder 2 drive device 3 heater part 4 input part 5 extraction part 6 connection part 7a supply ventilation pipe 7b discharge ventilation pipe 8 tilting device 9 extension end part 10 rotary drum rear end 11 heater box 12 bearing 13 tilting fulcrum part 14 cylinder part 15 switching valve 16 supply container 17 take-out container 18 glove box 19 bellows 20 exhaust hole 21 outer cylinder part 22 partition film 23 exhaust fan 24 intake port X air supply pipe Y exhaust pipe

Claims (1)

[Claims] 1. A horizontally-arranged cylindrical rotating cylinder, a drive device for rotating the rotating cylinder about its axis, an inclining device for inclining the rotating cylinder, and a periphery of the rotating cylinder. Heater part, an input part for inputting nuclear fuel scrap to the rotary cylinder, an extraction part for extracting nuclear fuel scrap from the rotary cylinder, a connecting part for connecting the input part and the extraction part to the rotary cylinder, and the rotary cylinder And a supply / exhaust pipe for supplying / discharging the atmosphere gas, narrowing one half of the rotary drum in a tapered shape, and connecting the extended end portion to the side portion of the connecting portion so as to be rotatable. The input part is connected to the upper part of the connection part, and the extraction part is connected to the lower part so as to be openable and closable, and the supply / exhaust pipe is connected to the connection part so that the connection part, the input part, and the extraction part are exposed to the outside air. Stored in a glove box that shuts off, An oxidation / reduction furnace for nuclear fuel regeneration, characterized in that the rotating drum, the drive unit, the heater unit, and the tilting unit are arranged outside the glove box.