KR20060035916A - Treatment method of lung coat - Google Patents

Abstract

Disclosed is a method for treating a closed capillary tube that can safely and efficiently remove radioactive material remaining in the closed capillary tube. The method for treating the pulmonary coating tube may include placing the pulmonary coating tube from which the nuclear fuel is separated in a hot cell, pressurizing the pulmonary coating tube in the longitudinal direction to flatten the lung coating tube, and cutting the lung coating tube along the bending line formed on both sides of the lung coating tube. And removing the radioactive material remaining in the incisional closed canal. By placing the closed coat tube in the hot cell, it is possible to fundamentally block the influence of the radioactive material, and the radioactive material remaining in the closed coat tube can be easily removed through the planarization and incision process. In addition, since the process is simple, most processes can be controlled remotely from a hot cell, and it is easy to implement remote control.

Lung coat, treatment, hot cell

Description

Treatment method of lung coat tube {METHOD FOR TREATING A NUCLEAR HULL}

1 is a view for explaining the step of placing the nuclear fuel rods in the hot cell in the method for treating the closed tube according to an embodiment of the present invention.

2 is a view for explaining a step of generating a closed capillary by removing the fuel from the cladding of the nuclear fuel rod in the method for treating the closed capillary tube according to an embodiment of the present invention.

3 is a view illustrating a state in which the lung coating tube is placed on a press in the lung coating tube treatment method according to an embodiment of the present invention.

4 is a view for explaining a process of pressurizing a closed coating tube by using a press in the processing method of the closed coating tube according to an embodiment of the present invention.

5 is a view for explaining the process of flattening and incision of the closed capillary tube by the press in the closed capillary tube processing method according to an embodiment of the present invention.

6 is a view for explaining the step of performing a dry decontamination of the incision in the closed capillary plate in the method for treating the capillary tube according to the embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

H: Hot cell 10: Nuclear fuel rod

12: Covering pipe 20: Closed coating pipe

25: Closed cover pipe 30: Press

32: Punch 34: Die

36: Iron brush 40: Dry decontaminated closed coat plate

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to the treatment of a closed capillary tube, and more particularly, to a method for treating a closed capillary tube, in which the radioactive material remaining in the closed capillary tube is economical, the process is simple, and can be removed by remote control. And a processing apparatus.

Nuclear power generates thermal energy by slowly reacting nuclear fuel in a reactor, and generates electricity using the generated energy. At this time, uranium dioxide is mainly used as a nuclear fuel, and uranium dioxide undergoes fission reactions in a reactor in a form of fuel rods. The nuclear fuel rod is formed with a diameter of about 10 mm and a length of about 4 m, and the cladding tube is made of a Zircalloy alloy having a thickness of about 1 mm. .

As already mentioned, nuclear fuel used for nuclear power is loaded with fuel produced in the form of pellets in each fuel rod cladding, and then used in bundles of dozens or hundreds of fuel rods. According to the conventional method, the spent fuel assembly burned in a nuclear power plant is stored and stored in a tank without being processed anymore, but as the period of operation of the nuclear power plant becomes longer, the amount of used nuclear fuel rods gradually accumulates, resulting in a large amount of spent fuel rods. It needs storage space. In addition, as the accumulated waste increases, the necessity and risk of dealing with the increased waste continues to be pointed out.

In some countries, spent fuel rods are transported to permanent disposal sites for long-term storage, while others are separated from cladding for the purpose of recycling spent fuel.

In order to recycle the fuel, after the use in the reactor is completed, the fuel rods are disassembled to separate the fuel and the cladding, and thus, a waste coating tube is generated in the process of treating the spent fuel. However, in the present technology, when the spent fuel is separated from the cladding, the waste cladding generated in these processes contains a radioactive product such as uranium or plutonium, nuclear fission products, and radioactive products resulting from the radiation of the cladding material. These closed coatings are classified as high-level radioactive waste. In particular, when the nuclear fuel is separated by a wet process, a special treatment is required because a nuclear material having a high radioactivity level, such as a fuel dissolving solution, is applied to the inner and outer surfaces of the waste coating tube.

In fact, one ton of fuel bundles weighs about 300 kg, which corresponds to about 30% of the total, and in terms of volume, more than twice as much fuel as spent lungs takes up. As a result, the treatment of waste coating tube during nuclear fuel processing takes a lot of time and money, and the processing process is complicated, so the place where it can be disposed of is limited, and the time until it can be safely processed and recycled is also long. There is a problem that can not be recycled quickly.

In this regard, the waste coating pipe, which is currently a high radioactive waste, is compressed, melted, and reduced as it is generated in the treatment process, and then the solidified body is packaged in a suitable medium, and then disposed of. However, compression or melting of the closed coating tube as it has high radioactivity deteriorates the ductility, hardness, and corrosion resistance of the closed coating tube (Zircaloy) due to the radioactivity remaining in the closed coating tube. Ingot fabrication and long term disposal stability can be difficult.

Therefore, if only the high-level radioactive material fixed on the inner surface of the closed coating can be removed from the coating, the closed coating can be classified as medium / low level waste.

If waste coating can be classified as medium / low level waste, the disposal period, as well as the disposal period, will be considerably shortened, and economical cost savings will be realized in that the expensive zircaloy alloy can be recycled. However, only these problems have been raised, they are only discussed in theory, and are not actually realized.

In order to overcome the above-mentioned problems, one object of the present invention is to provide a method for treating a closed tube that can effectively remove the high radioactive material remaining on the surface of the closed tube of the spent nuclear fuel (hull).

Another object of the present invention is a simple method of processing to enable remote control, there is no evaporation of high-radioactive substances due to the generation of dust or heating, and a method of treating a dry coated pipe made of dry to minimize the generation of secondary waste To provide.                         

It is still another object of the present invention to provide a method for treating a closed coating tube, which can significantly reduce the limitations and disposal periods associated with the disposal site in treating the closed coating tube, and recycle the expensive Zircaloy alloy in a short cycle.

According to a preferred embodiment of the present invention for achieving the above object of the present invention, the method for treating the closed capillary tube is located in the hot cell to the lung capillary separated from the nuclear fuel, pressurizing the closed capillary tube in the longitudinal direction to the closed capillary tube Planarizing, cutting the lung coating tube along a bent line formed on both sides of the lung coating tube, and removing radioactive material remaining in the cut lung tube.

After the fuel is separated from the fuel rods, the waste coating tube remains, and the remaining waste coating tube contains not only fuel materials such as uranium and plutonium, but also radioactive products resulting from the radiation of other fission products and cladding materials. Therefore, closed-coated pipes are classified as high-level radioactive waste. Although a wet process has been used as a method for removing radioactive material from the closed coating tube, there are many limitations in the case of the wet process because the nuclear fuel dissolving solution in which the radioactive substance is dissolved is applied to the inner and outer surfaces of the closed coating tube. .

However, the treatment method of the closed coating tube according to the present invention is characterized by removing the residue of the closed coating tube through a dry process rather than wet. Conventionally, the spent fuel rods are stored in a water tank or stored underground, but the method of treating the waste coating pipe according to the present invention is safe because it can classify the waste coating pipe from the high level waste to the medium / low level waste, and the high level waste is heavy. Conversion to low-level waste may overcome the limitations of the repository site and disposal period for the treatment of waste coatings. In addition, it is possible to prevent deterioration of the zircaloy metal by shortening the disposal period, and to secure expensive Zircalloy metal at a lower cost by shortening the cycle of recycling.

According to the present invention, for this purpose, the pulmonary coating tube is basically treated in a hot cell.

Hot-Cell refers to a compartment that can provide sufficient shielding to handle strong radioactive material. It is often said to be smaller than a shielded facility (hot cave) with experimental equipment for handling radioactive material, and it can be safely tested by remote control devices such as manipulators outside the shield wall.

After placing the closed coat tube in the hot cell, the closed coat tube is pressurized using a hydraulic press or the like. The closed coating pipe is bent flat by a hydraulic press, where the closed coating pipe is flattened on the basis of the bending lines formed on both sides. Even when the upper and lower sides of the closed coating tube are in contact with each other or before, the closed coating tube is continuously bent, and eventually the closed coating tube is cut along the bending line and separated into a flat upper and lower plate. Since the closed coating tube is separated into flat upper and lower plates, the radioactive substance remaining on the inner surface of the closed coating tube can be easily removed.

By flattening and cutting the cylindrical closed canal, the radioactive material can be easily removed, and at the same time, the process can be remoted so that the process can be easily carried out even in a hot cell, the work process is simple, and due to dust generation or heating Since there is no evaporation of high radioactive material and it is dry, the generation of secondary waste can be minimized.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited or limited by the embodiments.

1 to 5 are views for explaining a method for treating a closed capillary tube according to an embodiment of the present invention.

Referring to FIG. 1, a hot cell H is provided. The hot cell (H) is a space for treating radioactive material, and is composed of a concrete wall surface of about 1m or more, and is configured as a shielding facility to block the leakage of radiation.

In addition to the blocking facility, the hot cell H may be provided with a remote control device such as a manipulator for remote control. The remote control device may handle an object inside the hot cell H from the outside of the hot cell H through the remote control device. In addition, by keeping the internal pressure of the hot cell H relatively lower than the external air pressure, it is possible to prevent the substance inside the hot cell H from flowing out of the hot cell H in advance.

After use, the nuclear fuel rod 10 is transferred into the hot cell (H) and passes through a process such as separation and storage in the hot cell (H). In the present embodiment, the separation of the nuclear fuel rod 10 and the treatment of the closed tube in the same hot cell (H) is performed, but the above processes may be performed in different hot cells.

Referring to FIG. 2, the cap sealed by welding at the end of the nuclear fuel rod 10 is removed, and the radioactive material inside the sheath 12 is separated from the sheath 12. Through this process, the lung coating tube 20 is generated. The closed coating tube 20 is a cylindrical body made of Zircaloy metal, and the fuel residue, the fuel reaction product, the radioactive product of the cladding tube 12, and the like remain inside the cylindrical body.

Referring to FIG. 3, the waste coating tube 20 from which the nuclear fuel is separated is placed on the press 30. The press 30 includes a die 34 which is located at the bottom and which can press the closed coating tube 20 and a punch 32 which can press the closed coating tube 20 while moving up and down with respect to the die 34. do. Since the contact surface of the punch 32 and the die 34 is processed flat, the closed coating pipe 20 is pressed flat by the punch 32 and the die 34.

Referring to FIG. 4, as the punch 32 approaches the cylindrical closed coat tube 20, the closed coat tube 20 begins to be bent flat. As the punch 32 approaches the die 34, the closed coating tube 20 is gradually flattened, and the bent line FL oriented in the longitudinal direction is formed on both sides of the closed coating tube 20.

The closed coating tube 20 is plastically deformed around the bending line FL, and the closed coating tube 20 is flatly deformed up and down. At this time, the largest deformation is made at the outermost side of the bending line FL.

As the outermost stress of the bending line FL passes through the maximum stress, the closed coating tube 20 begins to fracture from the outermost side, and a crack is formed outward of the bending line FL. As the punch 32 of the press 30 approaches, the closed coating tube 20 starts to be cut around the crack, and the closed coating tube 20 is cut along the bending line FL.

Referring to FIG. 5, by cutting along the bending line, the closed coat tube 20 is separated into two flattened plates 25, and the inner surface 26 of the closed coat tube 20 in which radioactive material remains inside the plate. Is exposed.

Referring to FIG. 6, the inner surface 26 of the exposed closed tube plate 25 can be easily decontaminated using the iron brush 36 or the like. If the closed capillary plate 25 immediately after being cut is classified as high level waste, the closed capillary plate 40 after decontamination can be classified as medium / low level waste.

According to this embodiment, since the inner surface of the waste covering pipe 20 is cleaned by a dry process through the iron brush 36, secondary radioactive waste is not generated. In addition, it is possible to minimize the generation of dust and the like by using a glove box (glove box). Of course, by using an automatic cleaning device, it is also possible to remove the radioactive material remaining on the plate through the remote control.

The waste covering pipe 20 before removing the radioactive material is a high-level waste, and there are many restrictions on the disposal site and the disposal period. However, the planarizing and cutting the closed capillary 20 in this manner to produce the closed capillary plate 25, it is possible to easily remove the radioactive material remaining on the inner surface 26 of the flattened closed capillary plate 25. In addition, the decontaminated closed tube plate 40 may be classified as medium / low level waste by removing radioactive material from the closed tube plate 25. That is, the waste coating pipe 20, which is a high level waste, can be classified as a medium / low level waste which can be easily processed through the above-described process and recycled after about 50 years.

Compared to the treatment of high-level wastes, the treatment of low- and medium-level wastes has considerably fewer limitations in terms of space, time, and environment, which facilitates the treatment of waste coatings, and the physical and human resources consumed for processing as the process becomes easier. It is very economical because it saves money.

In addition, since the process of flattening and cutting the closed coating tube by the press can be performed at a time, the number of processes is reduced and the difficulty of the process is lowered. In addition, since these processes are generally not complicated and simple, they can be easily implemented by an automation device and relatively remotely controlled.

In addition, separating and disposing of cladding from spent nuclear fuel is much more economical than conventional methods, can reduce the construction cost and site limitations of the disposal site, and drastically shorten the disposal time required for safe disposal, thereby reducing the cost of expensive metals. You can also recycle.

In order to meet the international flow of nuclear material handling and disposal, the process must be carried out dry, with nuclear nonproliferation, while at the same time the work must be done in a hot cell, so the work is simple and the machinery used must not be complex.

By cutting and flattening the waste coating tube, the applicable removal methods or processes can be more diversified, and the effect of removing radioactive materials can be maximized, minimizing the generation of process waste, and further improving the stability of disposal. In addition, it can be expected to reduce the cost of construction site, land area and disposal period, and ultimately reduce the cost of electricity generation.

According to the present invention, the waste coating tube which has been permanently treated as a high-level waste can be converted to an easy dry decontamination state through a planarization and incision process, and the above-described processes are performed in a hot cell, thereby safely treating the waste coating tube.

In addition, the method for treating the closed capillary tube of the present invention is an innovative concept that has not existed in the past and has the advantage of being economical and simple in process and safe. In addition, because the process is simple, it does not require long training and can be put into action immediately, and the remote control facilitates the safe handling of hazardous radioactive waste.

As described above, it is very economical to separate and recycle nuclear fuel from the nuclear fuel rods, and research on this is being actively conducted. The method for treating pulmonary capillaries according to the present invention can indirectly assist the study by reducing the burden on the treatment of pulmonary capillaries. In addition, since the waste coating tube itself is an expensive metal, the recycling method of the waste coating tube can be extended and the recycling cycle can be shortened according to the treatment method of the present invention, and the rate of recycling can be significantly increased.

Of course, by sorting the waste covering pipes, which occupy about 40 to 50% of the volume of nuclear fuel waste, as low and middle level waste, the construction cost, land area and disposal period of the disposal site can be drastically reduced, which is very economically advantageous. have.

As described above, the present invention has been described with reference to the preferred embodiments, but those skilled in the art can variously modify the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated that it can be changed.

Claims (6)

Positioning the closed coat tube in which the nuclear fuel is separated into the hot cell; Pressurizing the closed coating tube in a longitudinal direction to planarize the closed coating tube; Cutting the lung coating tube along a bending line formed at both sides of the lung coating tube; And And removing the radioactive material remaining in the cut-off tube. The method of claim 1, In the step of placing the spent coating in the hot cell, the spent fuel rod is placed in the hot cell, and after disassembling the fuel rod, the fuel is separated from the decomposed fuel rod and stored separately, and the remaining waste tube The treatment method of the pulmonary coat tube, characterized in that the treatment in the hot cell. The method of claim 1, In the step of flattening the closed capillary tube, the closed capillary tube is placed on a press, the upper punch of the press presses the closed capillary tube as it approaches the lower die, and the cylindrical closed cap tube is deformed while both sides of the closed capillary tube are deformed. The bending line is formed in the longitudinal direction on both sides at And at the same time as the planarizing of the closed capillary tube, the closed capillary tube is cut into two closed capillary plates along the bending line. The method of claim 1, And removing the radioactive material in the step of removing the radioactive material. The method of claim 1, The internal air pressure of the hot cell is a treatment method of the lung coating tube, characterized in that it is maintained lower than the external air pressure. The method according to any one of claims 1 to 5, The process of transporting, flattening, and dissecting the closed capillary tube is performed by a remote control external to the hot cell.

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