KR20200123656A - Apparatus for Coating Nuclear Fuel Cladding - Google Patents

Abstract

The present invention relates to an apparatus for forming a film which can homogeneously and effectively form a film with high resistance to high-temperature oxidation on a long nuclear fuel cladding pipe simply by a one-time film forming process. The apparatus for forming a film on a nuclear fuel cladding pipe base material of a long tube shape comprises a chamber, a carrier, a heater, a cathode, an arc generation source, and a pump. The chamber provides a prescribed space to form the film on the nuclear fuel cladding pipe base material in a vacuum atmosphere. The carrier can be inserted into the chamber or withdrawn from the inside of the chamber by loading a plurality of nuclear fuel cladding pipe base materials. A negative bias is applied to the chamber while the carrier is inserted into the chamber, and the carrier can rotate the plurality of base materials at the same speed. The heater heats the plurality of nuclear fuel cladding pipe base materials and the atmosphere inside the chamber. A chrome target to be deposited on the base materials is loaded on the cathode. The arc generation source generates arc discharge to the cathode to cause evaporation and ionization of the chrome target in the cathode to create chrome ions. The pump discharges gas inside the chamber to the outside. The chrome ions created in the cathode by the arc generation source are guided to the carrier to simultaneously form a film on the plurality of nuclear fuel cladding pipe base materials loaded on the carrier.

Description

Apparatus for Coating Nuclear Fuel Cladding {Apparatus for Coating Nuclear Fuel Cladding}

The present invention relates to an apparatus for forming a film for a mechanical component, and more particularly, to an apparatus for forming a film for coating by an arc ion plating method.

The fuel used in the light water reactor (LWR) is composed of oxide sintered bodies or pellets composed of uranium oxide or mixed uranium/plutonium oxide. These pallets are placed in a long tube called a cladding tube to form a fuel rod. The fuel clad tube forms a barrier against radioactive fission products released from the fuel pallet during a nuclear reaction (see Patent Documents 1 and 2). As the fuel clad tube material, it is necessary to select a material that can secure an economical fuel cycle and has the characteristics necessary for safe reactor operation.

Specifically, the fuel-clad pipe is required not only to have high thermal conductivity so as to efficiently transmit internal energy, but also to have a small neutron absorption cross-section so that neutrons must be used efficiently. In addition, the fuel-clad pipe is exposed to cooling water at a pressure of about 15 MPa and a temperature of about 320°C, and it is desirable to have high corrosion resistance to withstand such high-temperature and high-pressure corrosive environments and embrittlement due to neutron irradiation.

For this reason, zirconium alloys are mainly used as fuel clad pipes. Zirconium has the lowest degree of absorbing neutrons among natural metals, so it hardly absorbs neutrons, and has excellent heat resistance and corrosion resistance. In particular, in nuclear reactors, including fuel-clad pipes, zircaloy, an alloy made by adding tin, nionium, iron, chromium, and nickel to zirconium in a weight ratio of less than 2%, is widely used. This zirconium alloy has excellent mechanical strength, creep resistance, corrosion resistance, and thermal conductivity at high temperatures, and has low neutron absorption properties.

However, due to extreme environmental conditions, even fuel-clad pipes made of zirconium alloys may deteriorate reliability due to abrasion and corrosion, particularly at high temperatures of 1,000°C or higher. If an unexpected natural disaster such as an earthquake or an event such as a failure of the cooling pump occurs during operation of the reactor, the temperature of the nuclear fuel rod rises, then zirconium reacts with the cooling water or steam in the reactor to generate zirconium oxide and hydrogen gas. The generated hydrogen gas can rapidly pressurize the reactor and ultimately cause an explosion, which can lead to catastrophe. For this reason, the outer circumferential surface of a zirconium alloy fuel-clad pipe is usually coated with metallic chromium or its alloy, and this coating not only increases the life of the fuel-clad pipe by 3 to 4 times, but also has excellent resistance to high temperature oxidation due to excellent corrosion resistance Thus, it is known that the surface of the fuel-clad pipe is protected from oxidation.

However, since the fuel-clad pipe is in a thin and long shape with a diameter of about 1 centimeter (cm) and a length of about 4 meters (m), it is very difficult to coat. Patent Documents 3 to 5 propose a method of spray coating a coating material such as chromium on a base material made of a zirconium alloy. However, spray coating has a problem in that it is difficult to pass the base material in the coating process, and it is difficult to obtain a homogeneous coating surface. In order to make the coated surface homogeneous, excessive time may be required, or a pretreatment such as sandblasting and/or a post-treatment such as heat treatment may be required, thereby complicating the coating process.

It is also possible to consider a method of dividing a long fuel-clad pipe up to 4 m into two or more and combining it after coating, but such a fuel-clad pipe may have a problem that mechanical stability or durability is weakened.

US 5,319,690 A (Combustion Engineering Inc.) June 7, 1994 US 5,227,129 A (Combustion Engineering Inc.) June 13, 1993 WO 2018/017146 A1 (Westinghouse Electric Co LLC) January 25, 2018 Registered Patent Publication No. 10-1393327 (Korea Hydro & Nuclear Power Co., Ltd., Korea Atomic Energy Research Institute) 2013. 5. 1. Registered Patent Publication No. 10-1843308 (Shinhwa Metal Co., Ltd.), 2018. 3. 22.

An object of the present invention is to provide a film forming apparatus capable of homogeneously and effectively forming a film having high resistance to high temperature oxidation in a single film forming process on a long nuclear fuel coated tube.

According to an aspect of the present invention for achieving the above technical problem, a film forming apparatus is for forming a film on a long tube-shaped nuclear fuel-coated tube base material, a chamber, a carrier, a heater, a cathode, an arc generator, a pump, and It has a control unit. The chamber provides a predetermined space for forming the film on the base material of the nuclear fuel coated tube in a vacuum atmosphere. The carrier may be loaded into the chamber by sliding in a state loaded with a plurality of nuclear fuel-coated tube base materials, or may be withdrawn from the chamber, and a negative bias is applied to the chamber while being loaded into the chamber. The base material of can be rotated at the same speed. The heater heats the internal atmosphere of the chamber and the plurality of nuclear fuel coated tube base materials. The cathode is loaded with a chromium target to be deposited on the base material. The chromium used for the chromium target may be pure chromium, a chromium alloy, a chromium-based alloy, or a chromium-containing alloy, or a combination thereof. The arc generating source generates an arc discharge at the cathode to cause evaporation and ionization of the chromium target at the cathode to generate chromium ions. The pump discharges the gas inside the chamber to the outside. The control unit controls operations of the carrier, the heater, the arc generator, and the pump. Accordingly, under the control of the control unit, chromium ions generated at the cathode by the arc generator are guided to the carrier to simultaneously form a film on the plurality of nuclear fuel clad tube base materials loaded on the carrier. Here, the distance between the cathode and the arc generating source and the base material is determined in a range of 50 to 200 mm, or is configured to be adjustable within this range.

In one embodiment, the carrier is disposed to extend in the transfer direction to the inside and outside the chamber, a plurality of rotation support rods that allow any one of the plurality of base materials to be stacked between each; A rotation support rod driving unit provided at at least one end of the plurality of rotation support rods to rotate the plurality of rotation support rods; And a support member for supporting the plurality of rotational support rods from below.

In another embodiment, a plurality of lower barrier members allowing the carrier to be loaded so that any one of the plurality of base materials extends in the transfer direction into and out of the chamber; And a base material rotation drive unit provided at at least one end of the plurality of base materials to rotate the plurality of base materials.

The pump includes a first pump for making the inside of the chamber a high vacuum state; And a second pump for making the inside of the chamber into a medium vacuum or low vacuum state.

According to another aspect of the present invention, a film forming apparatus is for forming a film on a long tube-shaped base material, and includes a chamber, a carrier, a heater, a cathode, an arc generator, and a pump. The chamber provides a predetermined space for forming the film on the base material in a vacuum atmosphere. The carrier may be loaded into the chamber by sliding in a state loaded with a plurality of base materials, or may be withdrawn from the chamber, and a negative bias is applied to the chamber while being loaded into the chamber, and the plurality of base materials Can be rotated at the same speed. The heater heats the internal atmosphere of the chamber and the plurality of base materials. A target material to be deposited on the base material is loaded on the cathode. The arc generating source generates an arc discharge in the negative electrode, causing evaporation and ionization of the target material at the negative electrode to generate target material ions. The pump discharges the gas inside the chamber to the outside. The control unit controls the operation of the carrier, the heater, the arc generator, and the pump. Accordingly, the target material ions generated in the cathode by the arc generating source under the control of the controller are guided to the carrier to simultaneously form a film on the plurality of base materials loaded on the carrier.

According to the present invention, a film having high resistance to high temperature oxidation can be formed on a long nuclear fuel clad tube by only one film forming step. According to the fuel-clad pipe formed with a film according to the present invention, even if an unexpected natural disaster such as an earthquake or a failure of the cooling pump occurs during operation of the nuclear reactor and the temperature of the nuclear fuel rod increases, the surface oxidation of the fuel-clad pipe is suppressed. Disasters caused by hydrogen generation or hydrogen explosion can be prevented. In particular, since the film is formed homogeneously, corrosion resistance and high temperature oxidation resistance of the fuel-clad pipe as well as the film are improved, thereby increasing the disaster prevention effect.

In addition, since it is possible to simultaneously form a film on a plurality of fuel-clad pipes while rotating a plurality of fuel-clad pipes, there is an advantage in that work efficiency and productivity are greatly improved.

In addition, since the film is formed by arc ion plating, there is an advantage that the adhesion of the film to the fuel-coated tube and the deposition rate are very high.

1 is a schematic plan view of a film forming apparatus according to an embodiment of the present invention.
2 is a schematic front view of the film forming apparatus of FIG. 1.
3 is a schematic side view of the film forming apparatus of FIG. 1.
4 is a schematic plan view of a cladding carrier according to an embodiment of the present invention.
5 is a view showing a state in which a fuel clad tube base material is mounted on the cladding tube carrier of FIG. 4.
6 is a schematic cross-sectional view of an arc generator according to an embodiment of the present invention.
7 is a flow chart showing a film formation process according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic plan view of a film forming apparatus according to an embodiment of the present invention, FIG. 2 is a schematic front view of a film forming apparatus, and FIG. 3 is a schematic side view of a film forming apparatus. For convenience of explanation, Figs. 1 to 3 illustrate not only the external appearance of the device, but also a configuration provided inside the device. In the illustrated film forming apparatus, a plurality of fuel clad tube base materials are charged, and a film made of pure chromium, a chromium alloy or a chromium-based alloy, or a chromium-containing alloy is formed by an arc ion plating method using an arc evaporation source. It is formed simultaneously on the base material of a plurality of fuel crusts

Here, the fuel-clad tube base material may have a size of, for example, a length of 4 meters (m), an outer diameter of 9.8 millimeters (mm), and a thickness of 1 mm, but the present invention is not limited thereto. The fuel clad tube base material may be made of a metal zirconium or a zirconium alloy material such as zircaloy-2 or zircaloy-4. Here, zircaloy-2 contains about 1.4% by weight of tin, 0.15% by weight of iron, 0.1% by weight of chromium and 0.06% by weight of nickel, 1,000 ppm of oxygen, and the remainder of zirconium. Zircaloy-4 contains about 1.4 wt% tin, 0.21 wt% iron, 0.11 wt% chromium, 30 ppm nickel, 1200 ppm oxygen, and the balance zirconium. However, the material of the base material of the fuel-clad tube is not limited thereto, and for example, a chromium-aluminum alloy having a weight ratio of chromium and aluminum of approximately 9:1 may be used.

The chromium target that supplies the material for film formation may be made of pure chromium, may be made of a chromium alloy, a chromium-based alloy, or a chromium-containing alloy. Here, "pure chromium" means 100% metallic chromium, which may contain trace amounts of impurities that do not contribute to any metallurgical function. For example, pure chromium can contain several ppm of oxygen. "Chrome alloys" to chromium-based alloys" refer to alloys containing chromium as the dominant or multiple element, together with small but reasonable amounts of other elements contributing to a particular function. Chromium alloys are 80 to 99 atomic percent. Other elements of the chromium alloy may include one or more chemical elements selected from silicon, yttrium, aluminum, titanium, niobium, zirconium and other transition metal elements, such as 0.1 to 20 elements. A "chromium-containing alloy" is one containing chromium in an amount less than that of many elements, for example, a chromium-containing alloy contains 16 to 18% chromium and 10 to 14% nickel. In the following description, including the claims, the term "chrome" is used to mean any one selected from such pure chromium, chromium alloys to chromium-based alloys, and chromium-containing alloys. According to the present invention, the chromium film may be formed on at least a part of the outer circumferential surface of the base material of the fuel-clad tube to a thickness of, for example, 5 microns, but the present invention is not limited thereto.

1 to 3, the film forming apparatus is charged into the vacuum chamber 100 in a state in which a vacuum chamber 100 installed on the table 10 and a plurality of fuel-coated tube base materials are seated, and the vacuum chamber ( It is provided with a cladding carrier 200 that can be drawn out from 100.

The vacuum chamber 100 has a substantially rectangular parallelepiped shape, and provides a predetermined space to form a film by arc ion plating on the base material of the fuel-clad tube in a vacuum atmosphere. In one embodiment, the vacuum chamber 100 has a size of 912 mm x 4,652 mm x 500 mm. In the vacuum chamber 100, a plurality of doors 102a to 102d that can be opened and closed in front are installed on the front side, and a door 104 that can be opened and closed in a lateral direction is also installed on one side, and the other side opposite to the door 104 is also installed. A door 106 is installed. In addition, a plurality of doors 108a that can be opened and closed upward are also installed on the upper surface of the vacuum chamber 100.

A plurality of heaters 110, a plurality of arc generators 120, a turbo pump 160, and a rotary/booster pump 170 are installed in the vacuum chamber 100. In addition, a gas injection pipe for introducing a reactive gas or an inert gas such as argon (Ar) is installed in the vacuum chamber 100 so as to form a required partial pressure as described later. In addition, a feed through for applying a bias to the arc generating source 120, the heater 110, and the cladding tube carrier 200 is formed in the vacuum chamber 100.

In this embodiment, each of the plurality of heaters 110 is installed in the vacuum chamber 100 so as to face the fuel-clad tube base material around the arc generating source 120. The plurality of heaters 110 may increase the temperature of the inside of the vacuum chamber 100 and the temperature of the base material of the fuel-coated tube in the film forming process. In addition, the heater 110 also performs a function of blowing impurities attached to the base material of the fuel-coated tube at the beginning of the film forming process. In one embodiment, 32 heaters 110 are provided, and each heater 100 is implemented as a 1.5 kilowatt cartridge heater. The distance between each of the heaters 110 and the base material of the fuel-clad pipe that is the object to be treated can be adjusted in the range of 50 to 250 mm. On the other hand, an auxiliary heater 112 is installed under the covering tube carrier 200 charged into the vacuum chamber 100.

A plurality of arc generating sources 120 are installed inside the upper surface of the vacuum chamber 100. In the embodiment shown in Figs. 1 to 3, the plurality of arc generating sources 120 are in the bottom of the door 108a provided on the upper side of the vacuum chamber 100, the cladding tube carrier 200 so as to be able to face the cladding tube carrier 200 Several are installed along the line. In the illustrated embodiment, 24 arc generating sources 120 are provided. Each of the plurality of arc generating sources 120 has a cathode loaded with a chromium target as an arc evaporation source, and melts and evaporates from the cathode by arc discharge.

The arc generating source 120 has a cathode loaded with a chromium target, which is an arc evaporation source deposited and plated on a fuel-clad tube base material, and supports and fixes it, and generates an arc spot at the cathode so that a vacuum arc discharge occurs at the cathode. For arc discharge, a positive (+) potential is applied to the vacuum chamber 100 and a negative (-) potential is applied to the cathode, so that an arc discharge can occur between the vacuum chamber 100 and the cathode. By arc discharge, chromium is ionized at the same time as melting and evaporation occur. As mentioned above, the chromium constituting the chromium target may be any one selected from pure chromium, a chromium alloy or a chromium-based alloy, and a chromium-containing alloy.

The turbo pump 160 may discharge air, a reaction gas, or argon gas in the vacuum chamber 100 to the outside to make the inside of the vacuum chamber 100 a high vacuum state. The rotary/booster pump 170 is a combination of a rotary vane pump and a booster pump, and can quickly discharge air, reactive gas, or argon gas in the vacuum chamber 100 to the outside.

On the other hand, the cladding tube carrier 200 may slide on the rail 280 in a state in which a plurality of fuel clad tube base materials are seated to be charged into the vacuum chamber 100, and conversely may be drawn out from the vacuum chamber 100 to the outside. have. In a state charged into the vacuum chamber 100, the cladding tube carrier 200 supports a plurality of fuel clad tube base materials loaded thereon from below. At this time, in order to increase the adhesion of the chromium film deposited on the surface of the fuel-coated tube base material, the cover tube carrier 200 is additionally provided with a configuration for rotating the fuel-coated tube base material and a configuration for applying a bias voltage to the vacuum chamber 100. do.

In addition, the film forming apparatus includes a power supply unit and a control unit. The power supply unit may include an arc generating source power circuit provided for each of the 24 arc generating sources 120 and a bias power supply circuit for biasing the fuel-clad tube base material as described later. The control unit controls the overall operation of the device and can be configured based on a PC. In addition, the film forming apparatus may be connected to a compressor for introducing dry air into the vacuum chamber 100.

4 is a schematic plan view of a cladding tube carrier 200 according to an embodiment, and FIG. 5 is a view showing a state in which fuel clad tube base materials 99a to 99p are mounted on the cladding tube carrier 200. The cladding tube carrier 200 includes a plurality of rotational support rods 210a to 210q arranged to extend in a transport direction in and out of the vacuum chamber 100, and a first and a first provided at both ends of the plurality of rotational support rods 210a to 210q. It includes second gear assemblies 220 and 230 and support rollers 250a to 250q that are supported from below in a rotatable manner so that the rotation support rods 210a to 210q are not struck.

The first gear assembly 220 includes gears 220a to 220q provided corresponding to each of a plurality of rotation support rods 210a to 210q, and an auxiliary device that is inserted between the gears 220a to 220q to transmit power. It has gears (222a to 222p). In addition, the second gear assembly 230 is also inserted between the gears 230a to 230q provided corresponding to each of the plurality of rotation support rods 210a to 210q and the gears 230a to 230q to transmit power. It is provided with auxiliary gears (232a ~ 232p).

Each of the gears 220a to 220q has the same size and gear ratio. In addition, each of the auxiliary gears 222a to 222p has the same size and gear ratio. The auxiliary gear (222a) is meshed to these gears between the two gears (220a, 220b), the auxiliary gear (222b) is meshed to these gears between the two gears (220b, 220c), and each gear in this way The fields 220a to 220q and the auxiliary gears 222a to 222p are alternately arranged in sequence.

Accordingly, the gears 220a to 220q in the first gear assembly 220 may rotate in the same direction. Likewise, the gears 230a to 230q in the second gear assembly 230 may rotate in the same direction. The first gear assembly 220 and the second gear assembly 230 are driven by a motor (not shown). At this time, the first gear assembly 220 and the second gear assembly 230 are connected by a power transmission mechanism such as a chain or belt, and rotated at the same rotational speed, for example, 1-10 rpm by one motor. It is desirable to be able to do it.

The first rotational support rod 210a is coupled to the gear 220a of the first gear assembly 220 and the gear 230a of the second gear assembly 230 so that their axial centers coincide. The second rotation support rod 210b is coupled to the gear 220b of the first gear assembly 220 and the gear 230b of the second gear assembly 230 so that the axial center thereof is aligned. The remaining rotation support rods 210c to 210q are also installed between the first gear assembly 220 and the second gear assembly 230 in the same manner. Since the distance between each rotational support rod (210a~210q) is smaller than the outer diameter of the fuel clad tube base material (99a~99p), one fuel clad tube base material (99a~99p) will be mounted on the upper side between two adjacent rotational support rods. It has become possible.

Accordingly, in a state in which the cladding tube carrier 200 is charged into the vacuum chamber 100, the gears 220a to 220q of the first gear assembly 220 and the gears 230a to the second gear assembly 230 When 230q) rotates, the rotation support rods 210a to 210q also rotate, and the fuel clad tube base material 99a to 99p loaded on the rotation support rods 210a to 210q also rotates.

Meanwhile, a bias voltage having a negative (-) potential with respect to the vacuum chamber 100 in a state in which the cover tube carrier 200 is charged into the vacuum chamber 100 in the rotational support rods 210a to 210q of the cover tube carrier 200 It may be applied through the first gear assembly 220 or the second gear assembly 230. Accordingly, the chromium ions generated by the arc generating source 120 are guided to the fuel clad tube base material 99a to 99p by a bias voltage of negative (-) potential applied to the rotating support rods 210a to 210q so that they can be deposited. do.

According to the illustrated embodiment, 17 rotational support rods 210a to 210q are provided on the cladding tube carrier 200, and thus 16 fuel clad tube base materials 99a to 99p can be simultaneously loaded, so that the fuel clad tube base material 99a The film can be formed simultaneously at ~99p). However, the number of fuel clad tube base materials that can be treated at the same time is not limited thereto.

6 schematically shows an arc generator 120 according to an embodiment of the present invention. The arc generating source 120 according to the illustrated embodiment is coupled to a cathode 400 loaded with a chromium target, which is an arc evaporation source deposited and plated on the fuel-clad tube base material 99a to 99p, and supports and fixes it, and the cathode 400 ) By generating an arc spot to cause the melting and evaporation of chromium in the cathode 400. The arc generating source 120 includes a fixed plate 420, a body 422, a cathode holder 424, a cooling tube 426, a permanent magnet 428, a double shielding film 428, and a gas injection tube ( 432 and an igniter 434 are provided.

The fixing plate 420 includes the body 422, the cathode holder 424, the cooling tube 426, the permanent magnet 428, the double shielding film 430, the gas injection tube 432, and the igniter 434. This is to be fixed and supported, and is installed in a state insulated from the vacuum chamber 100.

The body 422 is supported and fixed by the fixing plate 420, a cathode holder 424 is installed on the top, and a cooling tube 426 is installed therein.

The cathode holder 424 is installed on the upper side of the body 422 to fix and support the cathode 400 as an arc evaporation source.

The cooling pipe 426 provides a path for the cooling water to flow, and prevents the arc generator 120 from being overheated in a portion other than the cathode 400, that is, the cathode holder 424 and other members.

The permanent magnet 428 is arranged so that a magnetic field penetrates perpendicularly to the cathode 400, induces an arc spot to be stably generated in the cathode 400, and chromium ions formed by evaporation and ionization at the cathode 400 are The helical motion along the magnetic line of force promotes the activation of chromium ions and makes it possible to form a coating film with high adhesion. In one embodiment, the permanent magnet 428 is disposed on the outside of the negative electrode 400 in the form of a disk and the negative electrode holder 424 in the annular shape and has an annular shape. However, this means that when the cathode 400 has a shape other than a disk shape, the permanent magnet 428 has a different shape corresponding to the shape of the cathode 400.

The double shielding film 430 has an excessively large size among the particles of the chromium target generated from the cathode 400, so that macro particles that deteriorate the deposition surface characteristics when deposited on the fuel-coated tube base materials 99a to 99p are the above. Prevents reaching the fuel clad pipe base material (99a~99p). This utilizes the characteristic that the macro particles fly at an angle of about 45° from the surface of the cathode 400, and a double shielding film 430 is installed to protrude upward from the surface of the cathode 400 so that the macro particles are Try to avoid reaching (99a~99p) as much as possible.

The gas injection pipe 432 supplies a reactive gas or an inert gas such as argon (Ar) into the vacuum chamber 100 so as to form a necessary partial pressure inside the vacuum chamber 100. In this way, instead of introducing the reactive gas through the gas injection pipe 432 around the cathode 400, a reactive gas inlet may be separately provided at one side of the vacuum chamber 100. Further, both the reaction gas inlet and the gas injection pipe 432 formed in the vacuum chamber 100 may be provided. If the gas injection tube 432 is installed adjacent to the cathode 400 as shown in FIG. 6, the melting temperature of the surface of the cathode 400 is increased and the work function is decreased, so that the generation of macro particles can be significantly reduced. .

The igniter 434 is for arc discharge ignition. That is, the initial arc discharge is facilitated so that the arc discharge start voltage can be lowered. To this end, a voltage of a positive (+) potential is applied to the igniter 434.

Meanwhile, in the vacuum chamber 100 of the film forming apparatus, a distance between the cathode 400 and the arc generating source 120 and the fuel-coated tube base material 99a to 99p may be determined in a range of 50 to 200 mm. . In another embodiment, this distance is configured to be adjustable within a range of 50-200 mm, for example through screw adjustment.

The film forming apparatus having such an arc generating source 120 may operate as follows. First, the turbo pump 160 is operated to make the inside of the vacuum chamber 00 in a vacuum state of about 10 ^-4 Torr or less, and then argon gas is introduced into the vacuum chamber 100 to form a required partial pressure, and the arc generating source 120 ) To generate an arc by applying a bias to the cathode 400. When an arc is generated, the chromium target is melted and evaporated as well as ionized to generate chromium ions. In this state, when a bias voltage having a negative (-) potential, for example -500 to -800 V, is applied to the rotating support rods 210a to 210q of the cladding tube carrier 200 with respect to the vacuum chamber 100, chromium ions Is attracted by the bias voltage of negative (-) potential, and is deposited and deposited on the fuel-clad tube base material 99a to 99p. At this time, as the rotational support rods 210a to 210q of the cladding tube carrier 200 rotate to rotate the fuel clad tube base materials 99a to 99p, a film may be uniformly formed on the fuel clad tube base material 99a to 99p.

The film formation process in the film forming apparatus as described above will be described in more detail with reference to FIG. 7. 7 is a flow chart showing a film formation process according to the present invention.

First, the fuel-clad tube base materials 99a to 99p are cleaned before being put into the film forming apparatus. After cleaning is completed, the fuel clad tube base materials 99a to 99p are mounted on the cladding tube carrier 200. At this time, one fuel-clad tube base material 99a-99p is mounted between the adjacent rotating support rods 210a-210q. When all of the fuel clad tube base materials 99a to 99p are mounted on the cladding tube carrier 200, the cladding tube carrier 200 is slid on the rail 280 to be charged into the vacuum chamber 100 (step 500).

When the charging of the cladding tube carrier 200 is completed, the turbo pump 160 is operated to discharge the air in the vacuum chamber 100 to the outside to bring the inside of the vacuum chamber 100 to a high vacuum state of about 10 ^-4 Torr or less. Make it (Step 502).

Subsequently, the heater 110 and/or the auxiliary heater 112 are operated to increase the atmosphere inside the vacuum chamber 100 and the temperature of the fuel-covered tube base materials 99a to 99p to about 150 to 300°C, Impurities remaining on the surfaces of the coatings 99a to 99p are burned or evaporated to be removed (step 504).

Next, argon gas is introduced into the vacuum chamber 100 to form a required partial pressure, and a bias is applied to the vacuum chamber 100 to the cathode 400 from the arc generating source 120 to generate an arc. At this time, the chromium target is evaporated and ionized. And while rotating the rotation support rods (210a ~ 210q) of the cladding tube carrier 200, a bias voltage having a negative (-) potential with respect to the vacuum chamber 100 is applied to the rotation support rods (210a ~ 210q). For example, when a large bias voltage of -500 to -800 V is applied, chromium ions are strongly induced by the bias voltage of negative (-) potential and collide with the fuel clad tube base material 99a to 99p, and the fuel clad tube base material 99a to 99p. The surface is etched (step 506). This etching process cleans the surface of the base material 99a to 99p of the fuel-clad tube, and increases the bonding strength of the film of chromium or chromium alloy deposited thereafter.

After that, while maintaining the pressure inside the chamber by maintaining the argon gas inside the vacuum chamber 100, the negative (-) potential bias applied to the rotating support rods 210a to 210q is lowered to -50 to -200 V. , Chromium ions are induced by a bias voltage to be deposited on the surface of the fuel-clad tube base material 99a to 99p (step 508). The chromium deposition proceeds until a film of sufficient thickness is formed. The time required for the deposition process in step 508 differs from the thickness of the film, the size of the bias, the material of the chromium target loaded on the cathode, and the amount of arc generated, but it may take 5 to 12 hours to form a film having a thickness of 30 to 50 microns. have. In this process, the rotational support rods 210a to 210q of the cladding tube carrier 200 continuously rotate to rotate the fuel clad tube base materials 99a to 99p, so that a film is uniformly formed on the fuel clad tube base material 99a to 99p.

When sufficient film formation is completed, the atmosphere inside the vacuum chamber 100 and the fuel-coated pipe on which the film is formed are cooled (step 510). At this time, substances such as argon gas and chromium ions that form the atmosphere inside the vacuum chamber 100 may be discharged to the outside by the rotary/booster pump 170, filled with air, and then naturally cooled, but the argon gas is discharged and injected repeatedly. , It is also possible to shorten the cooling time inside the vacuum chamber 100. At this time, instead of argon, a gas of other elements such as helium or nitrogen may be purged.

When cooling is completed, the clad tube carrier 200 is drawn out of the vacuum chamber 100 to recover the fuel clad tube. Since the coating is formed uniformly in the fuel-clad pipe in which the coating is formed, it is possible to significantly reduce the possibility of hydrogen generation and explosion by preventing corrosion of the fuel-clad pipe base material over a long period of time and reducing the possibility of oxidation at high temperatures.

Although preferred embodiments of the present invention have been described above, the present invention can be modified in various ways without changing the technical idea or essential features thereof, and can be implemented in other specific forms.

For example, in the embodiment described above, the first gear assembly 220 and the second gear assembly 230 transmit rotational power to the rotational support rods 400a to 400m, but in other embodiments, the first gear assembly 220 ) And the second gear assembly 230 may be omitted, and instead, a support member for supporting the rotational support rods 400a to 400m may be provided while driving the rotation of the rotational support rods 400a to 400m. .

Meanwhile, in the above, the gears in the first gear assembly 220 and/or the second gear assembly 230 transmit the rotational power generated by the motor to the rotational support rods 400a to 400m, and the rotational support rods 400a to 400a 400m), and accordingly, an embodiment in which the fuel clad tube base material 99a to 99p loaded on the rotation support rods 400a to 400m rotates, but in another embodiment, the gears are rotated support rods ( 400a~400m), but it is also possible to directly transmit rotational power to the fuel clad tube base material (99a~99p). In this embodiment, each fuel clad tube base material 99a to 99p is rigidly fastened so that it can be selectively axially coupled to the gears in the first gear assembly 220 and/or the second gear assembly 230 It is preferable that the member is provided. In addition, in this embodiment, the rotational support rods 400a to 400m may be replaced with one or more rollers. In particular, in order to prevent the coating thickness from being relatively thinner to the portion where the rollers contact the rotary support rod, the portion of the rotary support rod that the rollers contact may be changed over time. Since such an embodiment can be easily implemented by a person skilled in the art based on the above-described embodiment, a detailed description is omitted.

Therefore, the embodiments described above are illustrative in all respects and should be understood as non-limiting. The scope of the present invention is indicated by the claims to be described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

99a~99p: Fuel clad tube base material
10: table 100: vacuum chamber
102a~102d, 104, 106, 108a: door
110: heater 112: auxiliary heater
120: arc generator
160: turbo pump 170: rotary/booster pump
200: clad carrier 210a to 210q: rotating support rod
220: first gear assembly
220a~220q: gear 222a~222p: auxiliary gear
230: second gear assembly
230a~230q: Gear 232a~232p: auxiliary gear
250a~250q: support roller 280: rail
420: fixing plate 422: body
424: cathode holder 426: cooling tube
428: permanent magnet 428: double shielding
432: gas injection pipe 434: igniter

Claims (8)

As a film forming device for forming a film on the base material of a long tube-shaped nuclear fuel coated tube,
A chamber providing a predetermined space for forming the film on the nuclear fuel coated tube base material in a vacuum atmosphere;
A plurality of nuclear fuel-coated tube base materials may be slid and loaded into the chamber or removed from the chamber, and a negative bias is applied to the chamber while being loaded into the chamber, and the plurality of base materials are removed. A carrier capable of rotating at the same speed;
A heater for heating the inner atmosphere of the chamber and the plurality of nuclear fuel coated tube base materials;
A cathode on which a chromium target to be deposited is loaded on the base material;
An arc generator for generating an arc discharge at the cathode to cause evaporation and ionization of the chromium target at the cathode to generate chromium ions;
A pump for discharging the gas inside the chamber to the outside; And
A control unit for controlling operations of the carrier, the heater, the arc generator, and the pump;
And wherein chromium ions generated at the cathode by the arc generator are guided to the carrier under the control of the control unit to simultaneously form a film on the plurality of nuclear fuel clad tube base materials loaded on the carrier. The method of claim 1, wherein the carrier is
A plurality of rotational support rods disposed to extend in the transfer direction into and out of the chamber, and allowing any one of the plurality of base materials to be loaded between each of the plurality of rotational support rods;
A rotation support rod driving unit provided at at least one end of the plurality of rotation support rods to rotate the plurality of rotation support rods; And
A support member supporting the plurality of rotational support rods from below;
A film forming apparatus comprising a. The method of claim 1, wherein the carrier is
A plurality of lower barrier paper members that allow any one of the plurality of base materials to be loaded so as to extend in the transfer direction into and out of the chamber; And
A base material rotation drive unit provided at at least one end of the plurality of base materials to rotate the plurality of base materials;
A film forming apparatus comprising a. The method according to any one of claims 1 to 3, wherein the heater is
A main heater installed above or below the carrier in the chamber; And
An auxiliary heater installed on the opposite side of the main heater with respect to the carrier;
A film forming apparatus comprising a. The method of any one of claims 1 to 3, wherein the pump is
A first pump for making the inside of the chamber a high vacuum state;
A second pump for making the inside of the chamber into a medium vacuum or low vacuum state;
A film forming apparatus comprising a. As a film forming apparatus for forming a film on a long tube-shaped base material,
A chamber providing a predetermined space for forming the film on the base material in a vacuum atmosphere;
A plurality of base materials may be slid into the chamber by sliding in a loaded state, or may be withdrawn from the chamber, and a negative bias is applied to the chamber while the plurality of base materials are loaded at the same speed. A carrier that can be rotated into;
A heater for heating the inner atmosphere of the chamber and the plurality of base materials;
A cathode on which a target material to be deposited is loaded on the base material;
An arc generator for generating an arc discharge at the negative electrode to cause evaporation and ionization of the target material at the negative electrode to generate target material ions;
A pump for discharging the gas inside the chamber to the outside; And
A control unit for controlling operations of the carrier, the heater, the arc generator, and the pump;
And wherein the target material ions generated in the cathode by the arc generating source are guided to the carrier under the control of the control unit to simultaneously form a film on the plurality of base materials loaded on the carrier. The method of claim 6, wherein the carrier is
A plurality of rotational support rods disposed to extend in the transfer direction into and out of the chamber, and allowing any one of the plurality of base materials to be loaded between each of the plurality of rotational support rods;
A rotation support rod driving unit provided at at least one end of the plurality of rotation support rods to rotate the plurality of rotation support rods; And
A support member supporting the plurality of rotational support rods from below;
A film forming apparatus comprising a. The method of claim 6, wherein the carrier is
A plurality of lower barrier paper members that allow any one of the plurality of base materials to be loaded so as to extend in the transfer direction into and out of the chamber; And
A base material rotation drive unit provided at at least one end of the plurality of base materials to rotate the plurality of base materials;
A film forming apparatus comprising a.

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