Device for rapidly preparing ice film on surface of nuclear fuel rod

Abstract

The invention discloses a device for rapidly preparing an ice film on the surface of a nuclear fuel rod, the device comprises a shell, a grillwork is arranged in the shell, a zirconium alloy cladding pipe is arranged in the grillwork, at least one group of supercooled water nozzles are arranged at the same time, and the supercooled water nozzles are used for spraying supercooled water to the surface of the zirconium alloy cladding pipe. The supercooled water spray head is sequentially connected with the heat exchanger, the injection pump and the water storage tank, the heat exchanger is provided with a cold source, the cold source converts water in the water storage tank into supercooled water through the heat exchanger, and deionized water or ultrapure water is contained in the water storage tank; the supercooled water spray head comprises a main flow channel, the main flow channel is communicated with a spray nozzle, a pressure reduction flow channel is arranged outside the main flow channel, and the pressure reduction flow channel is communicated with the main flow channel. The ice film is arranged on the zirconium alloy cladding pipe through supercooled water, so that the surface of the prepared ice film is smoother, and the lubricating and anti-attrition effects are better.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear engineering, in particular to a device for rapidly preparing an ice film on the surface of a nuclear fuel rod. Background Art

[0002] In order to ensure the safe operation of nuclear reactors, nuclear power plants have very strict requirements on nuclear fuel components. Zirconium alloy cladding tubes are an important part of nuclear fuel assemblies. They are used in extremely harsh environments in the core structure. Nuclear fission in nuclear reactors will produce inert gases, mainly krypton and xenon. If the zirconium alloy cladding tubes of nuclear fuel rods are damaged, these highly radioactive inert gases will overflow and enter the cooling water of the reactor loop, affecting the normal operation of the nuclear power plant. Therefore, they need to have good surface integrity performance.

[0003] Zirconium alloy cladding tubes are usually fixed and positioned by grids: for each layer of grids, a spring sheet is used to press on one side and a rigid protrusion is used on the other side, and the two work together to position the cladding tube in the center. However, under the existing rod pulling method, the fuel rod assembly wears more seriously, increasing the probability of safety hazards during the service of the cladding tube. At the same time, the design and manufacturing process of the existing fuel assembly positioning grid is very complicated. If the structure of the positioning grid is to be changed, the workload will be greatly increased.

[0004] To this end, existing technicians have attempted to provide a lubricating film on the outer wall of the zirconium alloy cladding tube. For example, Chinese patent CN202010295011.2 discloses a brushing assembly and lubrication system for lubricating fuel rods, which coats a layer of water film on the fuel rods by setting a brushing roller with bristles, and lubricates the fuel rods through the water film, thereby reducing the wear of the zirconium alloy cladding tube. However, the thickness of the water film is relatively thin and its lubrication effect is limited; Chinese patent CN202310858855.7 discloses a device and method for inserting a nuclear fuel rod into a positioning grid of a nuclear fuel assembly, which sprays water mist through a humidifying nozzle and cools the water mist through a cooling refrigeration device to prepare an ice film or frost on the surface of the fuel rod. However, since the water mist freezes or frosts under relatively low temperature conditions, the prepared ice film or frost is unevenly distributed on the surface of the fuel rod, resulting in relatively poor lubrication effect; at the same time, in order to make the water mist freeze or frost quickly, the ambient temperature is relatively low. In this field, liquid nitrogen or dry ice is often used to prepare a corresponding low-temperature environment (below -40°C), which not only consumes a lot of energy, but also has a high safety risk. Summary of the invention

[0005] To solve at least one of the above problems, the present invention proposes a device for rapidly preparing an ice film on the surface of a nuclear fuel rod. The ice film prepared on the surface of a zirconium alloy cladding tube is relatively uniform, so that its lubrication effect is relatively high.

[0006] The technical solution of the present invention is as follows: it comprises a shell, a grid is arranged in the shell, a zirconium alloy cladding tube is arranged in the grid, and at least one group of supercooled water nozzles are arranged at the same time, the supercooled water nozzles are used to spray supercooled water on the surface of the zirconium alloy cladding tube, the supercooled water nozzles are connected to a heat exchanger, an injection pump and a water storage tank in sequence, the heat exchanger is provided with a cold source, the cold source converts the water in the water storage tank into supercooled water through the heat exchanger, and the water storage tank contains deionized water or ultrapure water; the supercooled water nozzle comprises a main channel, the main channel is connected to a nozzle, a pressure reducing channel is arranged outside the main channel, and the pressure reducing channel is connected to the main channel.

[0007] One embodiment of the present invention is that the nozzle outlet is provided with a rotating flow control piece that is in contact with the nozzle, and the rotating flow control piece is provided with a plurality of water control holes; the nozzle is provided with a plurality of water spray holes, and the relative positions of the water control holes and the water spray holes are adjusted by rotating the rotating flow control piece, thereby regulating the water spraying speed of the nozzle.

[0008] Furthermore, a driven gear is provided on one side of the rotating flow control plate, and the device is also provided with a micro motor, the outlet end of the micro motor is connected to a driving gear, and the driving gear cooperates with the driven gear.

[0009] An implementation manner of the present invention is that a heat-insulating layer is provided on the shell.

[0010] An embodiment of the present invention is that a heater for removing residual ice debris is provided in the housing.

[0011] An implementation manner of the present invention is that a group of supercooling water nozzles is provided with at least two nozzles, which are evenly arranged circumferentially around the axis of the zirconium alloy cladding tube.

[0012] Beneficial effects: The present invention sets an ice film on the zirconium alloy cladding tube through supercooled water, so that the surface of the prepared ice film is smoother and the lubrication and wear reduction effect is better; at the same time, by controlling the spraying time and spraying amount of the supercooled water nozzle, the thickness of the ice film can be adjusted, so that the prepared ice film is more controllable and can be applied to a variety of different situations, with a wider range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of this embodiment;

[0014] Figure 2 It is a schematic diagram of the setting of the supercooled water nozzle and the zirconium alloy cladding tube;

[0015] Figure 3 It is a schematic exploded diagram of the structure of the supercooled water nozzle and the rotating flow control piece;

[0016] Figure 4It is a schematic diagram of the structure of the supercooled water nozzle, the rotating flow control piece and the micro motor.

[0017] In the figure, 1 is a water storage tank, 2 is a heat exchanger, 3 is a shell, 4 is a grid, 5 is a zirconium alloy cladding tube, 6 is a supercooled water nozzle, 7 is an injection pump, 8 is a heater, 601 is a main channel, 602 is a pressure reducing channel, 603 is a nozzle, 604 is a rotating flow control plate, 605 is a water spray hole, 606 is a water control hole, 607 is a driving gear, and 608 is a micro motor. DETAILED DESCRIPTION

[0018] The specific implementation modes of the present invention will be described clearly and completely below with reference to examples and drawings. Obviously, the described examples are only some embodiments of the present invention, rather than all embodiments.

[0019] like Figures 1 to 4 As shown, it includes a shell 3, a grid 4 is provided in the shell 3, a zirconium alloy cladding tube 5 is provided in the grid 3, and at least one group of supercooled water nozzles 6 are provided. The supercooled water nozzles 6 are used to spray supercooled water on the surface of the zirconium alloy cladding tube 5. The supercooled water nozzles 6 are connected to the heat exchanger 2, the injection pump 7 and the water storage tank 1 in sequence. The heat exchanger 2 is provided with a cold source. The cold source converts the water in the water storage tank 1 into supercooled water through the heat exchanger 2. The water storage tank 1 contains deionized water or ultrapure water; the supercooled water nozzle 6 includes a main channel 601, the main channel 601 is connected to the nozzle 603, and the main channel 601 is provided with a pressure reducing channel 602 outside, and the pressure reducing channel 602 is connected to the main channel 601.

[0020] Specifically, the shell 3 is used to accommodate components such as the grid 4 and the zirconium alloy cladding tube 5 . Meanwhile, the ice film is prepared inside the shell 3 .

[0021] In order to facilitate the preparation of the ice film, at least one group of supercooled water nozzles 6 is provided inside the shell 3, and the supercooled water nozzles 6 can spray supercooled water onto the zirconium alloy cladding tubes 5 in the grid 4. When the supercooled water impacts the surface of the zirconium alloy cladding tubes 5, the supercooled water begins to freeze as the state of the supercooled water changes. At the same time, since the supercooled water is a fluid and can flow on the zirconium alloy cladding tubes 5, the entire outer surface of the zirconium alloy cladding tubes 5 begins to freeze as the supercooled water flows. When the supercooled water flows on the surface of the zirconium alloy cladding tubes 5, since the supercooled water is sprayed through the supercooled water nozzles 6, the supercooled water will form a uniform water film on the surface of the zirconium alloy cladding tubes 5. As the supercooled water freezes, the ice film finally formed is also relatively uniform, so that the lubrication effect of the ice film is better.

[0022] In order to make the ice film on the zirconium alloy cladding tube 5 more uniform, in this embodiment, a group of supercooled water nozzles 6 includes three supercooled water nozzles 6: the three supercooled water nozzles are evenly arranged around the axis of the zirconium alloy cladding tube, that is, the angle between two adjacent supercooled water nozzles is 120°. When in use, the three jointly spray supercooled water to the zirconium alloy cladding tube 5, and the water spraying amount of each supercooled water nozzle 6 is adjusted, so that the ice film on the zirconium alloy cladding tube 5 is more uniform. Of course, those skilled in the art can also set multiple groups of supercooled water nozzles 6 according to actual conditions, and each group includes different numbers of supercooled water nozzles 6.

[0023] For the supercooled water nozzle 6, when the pressure difference between the inside and outside is too large, the supercooled water may begin to freeze in the supercooled water nozzle 6, which not only causes ice blockage in the supercooled water nozzle, but also the uniformity of the ice film formed by the sprayed supercooled water on the zirconium alloy cladding tube 5 is relatively poor. In order to solve this problem, in this embodiment, a main flow channel 601 is provided in the supercooled water nozzle 6, and a pressure reducing flow channel 602 is provided outside the main flow channel 601. One end of the pressure reducing flow channel 602 is connected to the main flow channel 601, and the other end is connected to the outside through a safety valve. A corresponding nozzle 603 is provided at one end of the main flow channel 601, and a plurality of water spray holes 605 are provided on the nozzle 603. After passing through the heat exchanger 2, the supercooled water enters the main flow channel 601, and then sprays out through the water spray holes 605 on the nozzle 603. When the pressure in the main flow channel 601 is too high, part of the supercooled water will be discharged through the pressure reducing flow channel 602 and the safety valve, thereby relieving the pressure of the main flow channel 601.

[0024] In order to control the amount of supercooled water sprayed by the supercooled water nozzle 6, in this embodiment, a rotating flow control piece 604 is provided at the outlet of the nozzle 603, and the rotating flow control piece 604 can rotate around its axis. At the same time, a plurality of water control holes 606 are provided on the rotating flow control piece 604. When the positions of the water control holes 606 and the water spray holes 605 coincide, the supercooled water is sprayed through the water spray holes 605 and the water control holes 606; when the rotating flow control piece 604 rotates, the positions of the water control holes 606 will change, so that the flow rate of the supercooled water can be adjusted. For the rotating flow control plate 604, the number of its water control holes 606 is usually greater than the number of the water spray holes 605 of the nozzle 603, and when the rotating flow control plate 304 rotates to a certain angle, all the water spray holes 605 are opposite to one water control hole 606, so that the flow rate of the nozzle 603 reaches the maximum; as the rotating flow control plate 604 rotates, the number and area of ​​the water spray holes 605 opposite to the water control holes 606 change, causing the flow rate of the nozzle 603 to also change.

[0025] During actual use, the rotating flow control plate 604 can be adjusted manually or automatically. When manual adjustment is adopted, the rotating flow control plate can be set by means of bolts or damping. When the position of the rotating flow control plate 604 needs to be adjusted, the angle of the rotating flow control plate 604 can be adjusted manually to complete the adjustment of the flow of the nozzle 603.

[0026] However, in the actual production process, each supercooled water nozzle 6 needs to be adjusted. The manual adjustment method is not only cumbersome, but also produces large errors and wastes time. To this end, this embodiment proposes a structure for automatically adjusting the rotating flow control plate 604: the structure includes a micro motor 608, and a driving gear 607 is connected to the outlet end of the micro motor 608. At the same time, a driven tooth that can cooperate with the driving gear 607 is arranged on the side wall of the rotating flow control plate 604, and the driving gear 607 and the driven tooth are meshed. The rotating flow control plate 304 can be controlled by the micro motor 608, and the flow of the nozzle 603 can be adjusted.

[0027] With respect to the shell 3, since the device is used to prepare an ice film on the zirconium alloy cladding tube 5, if there is a strong heat exchange between the inside and outside of the shell 3, the stability of the ice film will decrease. For this reason, in the present embodiment, a thermal insulation layer is provided inside the shell, and the thermal insulation layer is supported by conventional thermal insulation materials, such as conventional polyurethane foam, etc., which are conventional thermal insulation materials in this field.

[0028] Since the present embodiment uses supercooled water to prepare an ice film on the surface of the zirconium alloy cladding tube 5, when the experiment is over, the supercooled water remaining in the body will condense into ice. In order to avoid this problem, the present embodiment is also provided with a corresponding heater 8, through which the temperature inside the shell 3 can be raised and the ice can be melted. These heaters 8 can be electric heating wires arranged on the shell 3, or heaters 8 such as hot air blowers.

[0029] For the water storage tank 1, the reason why corresponding deionized water or ultrapure water is set is that for conventional tap water, it contains a large amount of salt impurities, which will act as condensation nuclei in the process of water freezing, making it difficult to prepare corresponding supercooled water. For deionized water or ultrapure water, the internal salt content is extremely low, and it is difficult to form condensation nuclei, so it can be used to prepare supercooled water. For deionized water and ultrapure water, it can use existing deionized water and ultrapure water, and it can also use existing ultrapure water preparation machines and be prepared based on tap water.

[0030] When in use, add deionized water or ultrapure water to the water storage tank, then start the heat exchanger and injection pump to cool the deionized water and ultrapure water into supercooled water, and spray the supercooled water onto the surface of the zirconium alloy cladding tube through the supercooled water nozzle to form an ice film, and then perform rod drawing. The flow rate of the supercooled water nozzle can be adjusted by rotating the flow control piece, thereby adjusting the thickness of the ice film.

[0031] According to the inventor's experiments, the lubrication and wear reduction effect of the ice film of the present invention is improved by more than 90% compared with the water film coated by a brush; compared with the ice film prepared by rapid cooling at room temperature water under low temperature conditions (usually -40°C and below, see CN202310858855.7), the lubrication and wear reduction effect of the ice film of the present invention is improved by an average of 17%, and has stronger uniformity.

[0032] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A device for rapidly preparing an ice film on the surface of a nuclear fuel rod, characterized in that: It comprises a shell, a grid is arranged in the shell, a zirconium alloy cladding tube is arranged in the grid, and at least one group of supercooled water nozzles are arranged, the supercooled water nozzles are used to spray supercooled water on the surface of the zirconium alloy cladding tube, the supercooled water nozzles are connected to a heat exchanger, an injection pump and a water storage tank in sequence, the heat exchanger is provided with a cold source, the cold source converts the water in the water storage tank into supercooled water through the heat exchanger, and the water storage tank contains deionized water or ultrapure water; the supercooled water nozzle comprises a main channel, the main channel is connected to a nozzle, a pressure reducing channel is arranged outside the main channel, and the pressure reducing channel is connected to the main channel.

2. The device according to claim 1, characterized in that The nozzle outlet is provided with a rotating flow control plate that fits the nozzle, and the rotating flow control plate is provided with a plurality of water control holes; the nozzle is provided with a plurality of water spray holes, and the relative positions of the water control holes and the water spray holes are adjusted by rotating the rotating flow control plate, thereby regulating the water spraying speed of the nozzle.

3. The device according to claim 2, characterized in that The edge of the rotating flow control sheet is provided with driven teeth, and the device is also provided with a micro motor. The outlet end of the micro motor is connected with a driving gear, and the driving gear matches the driven teeth.

4. The device according to claim 1, characterized in that A heat-insulating layer is arranged on the shell.

5. The device according to claim 1, characterized in that A heater for removing residual ice debris is arranged in the shell.

6. The device according to claim 1, characterized in that A group of supercooling water nozzles is provided with at least two nozzles, which are evenly arranged around the axis of the zirconium alloy cladding tube.

Images