Ultrasonic cleaning and descaling device for pressurized water reactor fuel assembly capable of automatically separating dirt

Abstract

The invention discloses a dirt self-separation ultrasonic cleaning and descaling device for a pressurized water reactor fuel assembly. The dirt self-separation ultrasonic cleaning and descaling device comprises a spent fuel pool, an assembly cleaning mechanism, a dirt collecting tank, a dirt depositing tank, a first water circulating pipeline, a first filter assembly, a first circulating pump, a second water circulating pipeline, a second filter assembly and a second circulating pump. The dirt collecting tank is arranged on the bottom side of the assembly cleaning mechanism. The dirt deposition tank is arranged below the dirt collection tank; one end of the first water circulating pipeline is connected to the top of the dirt collecting tank, and the other end is communicated with the spent fuel pool; the first filter assembly and the first circulating pump are arranged on the first water circulating pipeline; one end of the second water circulating pipeline is connected to the dirt collecting tank, and the other end is communicated with the first water circulating pipeline; and the second filter assembly and the second circulating pump are arranged on the second water circulating pipeline. The problem that after ultrasonic descaling is carried out on the fuel assembly, deposited scales are discharged into a spent fuel pool, and the radioactive level is increased can be solved.

Description

An ultrasonic cleaning and descaling device for self-separating fouling in pressurized water reactor fuel assemblies. Technical Field

[0001] This application relates to the field of ultrasonic cleaning technology for pressurized water reactor fuel assemblies, and in particular to an ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies that allows for self-separation of fouling. Background Technology

[0002] During reactor operation, the high-temperature, high-pressure, and intensely irradiated water environment causes corrosion of the primary circuit structural materials and releases corrosion products into the coolant. These corrosion products migrate with the coolant in the primary circuit. Due to the increased working fluid temperature and nucleation boiling within the core, these corrosion products easily deposit on the fuel rod surfaces when they flow to the core with the coolant, forming an uneven fouling layer. This fouling layer has several adverse effects on reactor operation: Firstly, locally thick fouling on the fuel cladding surface reduces the effective contact between the fuel cladding and the coolant, hindering the fuel-coolant heat transfer process. This prevents the coolant from effectively removing heat from the fuel cladding surface, creating localized hot spots on the cladding surface, exacerbating localized corrosion and hydrogen absorption, ultimately leading to thinning and embrittlement of the cladding wall, thus threatening reactor safety. On the other hand, porous fouling layers can induce the localized deposition of borides added to the primary coolant on the fuel rods. Since boron is a neutron absorber, when boron is deposited on the fuel rods in an axially asymmetric manner, it causes a shift in reactor power from the bottom of the core to the upper middle, resulting in uneven axial power distribution. Ultimately, this necessitates reduced reactor power operation to avoid excessive cladding corrosion and thinning due to locally high power density, impacting reactor economics and safety. Furthermore, the main components of fouling, such as 60Co, 63Ni, and 55Fe, are activated by neutrons in the core and, with the circulation of the primary coolant, re-attach or deposit on main pipes, steam generators, pressurizers, and other components, leading to increased radiation doses during reactor shutdowns and overhauls, seriously threatening the safety of plant maintenance personnel. In conclusion, fouling on fuel assemblies not only affects the economics of nuclear power plants but also threatens reactor operational safety. Therefore, in-service pressurized water reactor nuclear power plants need to conduct fuel assembly fouling removal work as needed.

[0003] Currently, ultrasonic cleaning has proven to have good application prospects in descaling industrial systems such as pipelines and components, effectively removing scale buildup from the surfaces of pipes and other structures. However, unlike the descaling requirements of traditional industrial systems, the surface scale of reactor fuel assemblies has a high level of radioactivity, posing a significant threat to the environment and personnel safety. While simple ultrasonic descaling can effectively remove scale, the subsequent disposal of the scale and the spread of radioactive contamination during the descaling process are difficult to control. In other words, simply using ultrasonic descaling to discharge the accumulated scale into the spent fuel pool for reactor fuel assemblies will cause an increase in the radioactivity level of the spent fuel pool, triggering a chain reaction. Summary of the Invention

[0004] The main objective of this application is to provide an ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies that allows for self-separation of fouling. This device aims to solve the problem that the discharge of accumulated fouling into the spent fuel pool after ultrasonic descaling of reactor fuel assemblies can lead to an increase in radioactivity levels and trigger a chain reaction.

[0005] To achieve the above objectives, this application provides an ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling, comprising: a spent fuel pool, an assembly cleaning mechanism, a fouling collection tank, a fouling deposition tank, a first water circulation pipe, a first filter assembly, a first circulation pump, a second water circulation pipe, a second filter assembly, and a second circulation pump. The assembly cleaning mechanism is used to descale the surface of the fuel assembly and is disposed within the spent fuel pool. The fouling collection tank is disposed below and communicates with the assembly cleaning mechanism, and is used to collect the fouling cleaned from the surface of the fuel assembly by the assembly cleaning mechanism. The fouling deposition tank is disposed below and communicates with the fouling collection tank, and is used to collect the fouling from the surface of the fuel assembly by the fouling collection tank. The first water circulation pipe is connected to the top of the dirt collection tank at one end and to the spent fuel water tank at the other end. The first filter assembly is disposed on the first water circulation pipe for filtering dirt. The first circulation pump is disposed on the first water circulation pipe for drawing water from the first water circulation pipe. The second water circulation pipe is connected to the dirt collection tank at one end and to the first water circulation pipe at the other end, and the connection between the second water circulation pipe and the first water circulation pipe is located at the output end of the first circulation pump. The second filter assembly is disposed on the second water circulation pipe for filtering dirt. The second circulation pump is disposed on the second water circulation pipe for drawing water from the second water circulation pipe.

[0006] Optionally, a chemical purifier is also installed on the first water circulation pipe. The chemical purifier is located at the outlet end where the first water circulation pipe and the second water circulation pipe meet, and the chemical purifier is used to purify the water.

[0007] Optionally, the first filter assembly includes at least one first filter, which is connected to the first water circulation pipe; the second filter assembly includes at least one second filter, which is connected to the second water circulation pipe.

[0008] Optionally, a first inlet filter is provided at one end of the first water circulation pipe connected to the dirt collection tank. The first inlet filter is used to filter the dirt removed by ultrasonic cleaning, so that the dirt remains in the dirt collection tank. A second inlet filter is provided at one end of the second water circulation pipe connected to the dirt collection tank. The second inlet filter is used to filter the dirt removed by ultrasonic cleaning, so that the dirt remains in the dirt collection tank.

[0009] Optionally, the component cleaning mechanism includes: a fuel assembly hoisting mechanism, a component cleaning cylinder, and an ultrasonic generator, wherein the fuel assembly hoisting mechanism is used to hoist and move the fuel assembly; the component cleaning cylinder is disposed below the fuel assembly hoisting mechanism and is used to accommodate and clean the fuel assembly, the dirt collection tank is located on the lower side of the component cleaning cylinder and communicates with the component cleaning cylinder; the ultrasonic generator is disposed on the inner wall of the component cleaning cylinder and is movable along the direction in which the component cleaning cylinder extends.

[0010] Optionally, the component cleaning mechanism further includes a weighing component, wherein the weighing component is disposed on the fuel assembly hoisting mechanism and is used to weigh the fuel assembly.

[0011] Optionally, the component cleaning mechanism further includes a chemical injection mechanism, wherein the chemical injection mechanism is used to inject chemical agents into the surface of the fuel assembly to assist in descaling.

[0012] Optionally, a diversion plate is provided in the dirt collection tank, and the ends of the first water circulation pipe and the second water circulation pipe are respectively located on both sides of the diversion plate.

[0013] Optionally, the chemical injection mechanism includes: a dosing tank, a peristaltic pump, and a connecting hose, wherein the dosing tank is used to hold chemical agents; the peristaltic pump is connected to the dosing tank via a pipe and is used to extract chemical agents from the dosing tank; the input end of the connecting hose is connected to the output end of the peristaltic pump, and the output end of the connecting hose is connected to the ultrasonic generator and can inject chemical agents into the surface of the fuel assembly where descaling is required; the connecting hose is extendable.

[0014] Optionally, the fuel assembly hoisting mechanism includes: a base, a fixing frame, and a hoisting assembly, wherein the fixing frame is fixed to the base; and the hoisting assembly is disposed on the fixing frame for hoisting the fuel assembly.

[0015] This application discloses an ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling. During the cleaning process, the assembly cleaning mechanism descales the surface of the fuel assembly, and the generated fouling enters a fouling collection tank with the water flow. After the fouling is collected in the collection tank, it falls into a fouling deposition tank below under gravity for deposition. Simultaneously, a first circulation pump is activated, drawing water from the fouling collection tank through a first water circulation pipe. As the water flows through a first filter assembly, the fouling is filtered out. A second circulation pump is also activated, drawing water containing fouling from the fouling collection tank through a second water circulation pipe. This water passes through a second filter assembly, where the fouling is also filtered out. The water then merges with the filtered water in the first water circulation pipe and returns to the spent fuel pool, achieving water recycling and effective fouling separation. After the above treatment, the fouling and water are effectively separated, and the cleaning of the fuel assembly surface does not cause an increase in the radioactivity level in the spent fuel pool, thus preventing a chain reaction. Attached Figure Description

[0016] Figure 1 is a schematic diagram of an ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling provided in an embodiment of this application; Figure 2 is a schematic diagram of the installation structure of each component in Figure 1 in the spent fuel pool; Figure 3 is a schematic diagram of an embodiment of the fuel assembly hoisting mechanism in Figure 2.

[0017] In the diagram, 1. Fuel assembly hoisting mechanism; 101. Base; 102. Fixing frame; 103. Hoisting assembly; 2. Weighing assembly; 3. Chemical injection mechanism; 4. Ultrasonic generator; 6. Assembly cleaning cylinder; 7. Sludge collection tank; 8. Sludge deposition tank; 9. Diverter plate; 13. Second circulation pump; 17. First circulation pump; 18. Chemical purification device; 19. Spent fuel water pool; 20. Peristaltic pump.

[0018] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0021] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0023] Please refer to Figures 1 to 3. This application provides an ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling. The ultrasonic cleaning and descaling device may include: a spent fuel water tank 19, an assembly cleaning mechanism, a fouling collection tank 7, a fouling deposition tank 8, a first water circulation pipe, a first filter assembly, a first circulation pump 17, a second water circulation pipe, a second filter assembly, and a second circulation pump 13. The assembly cleaning mechanism is used to descale the surface of the fuel assembly and is located within the spent fuel water tank 19. The fouling collection tank 7 is located at the bottom of the assembly cleaning mechanism and communicates with it, used to collect the fouling cleaned from the surface of the fuel assembly by the assembly cleaning mechanism. The fouling deposition tank 8 is located below the fouling collection tank 7 and communicates with it. The collection tank 7 is connected to allow the dirt collected in the dirt collection tank 7 to settle; one end of the first water circulation pipe is connected to the top of the dirt collection tank 7, and the other end is connected to the spent fuel water tank 19; the first filter assembly is installed on the first water circulation pipe for filtering dirt; the first circulation pump 17 is installed on the first water circulation pipe for pumping water from the first water circulation pipe; one end of the second water circulation pipe is connected to the dirt collection tank 7, and the other end is connected to the first water circulation pipe, and the connection point between the second water circulation pipe and the first water circulation pipe is located at the output end of the first circulation pump 17; the second filter assembly is installed on the second water circulation pipe for filtering dirt; the second circulation pump 13 is installed on the second water circulation pipe for pumping water from the second water circulation pipe.

[0024] During the cleaning process, the component cleaning mechanism descales the surface of the fuel components, and the resulting dirt flows into the dirt collection tank 7 with the water flow. After the dirt is collected in the dirt collection tank 7, it falls into the dirt deposition tank 8 below under gravity for deposition. At the same time, the first circulation pump 17 starts, drawing water from the dirt collection tank 7 through the first water circulation pipe. When the water flows through the first filter assembly, the dirt is filtered out. The second circulation pump 13 also starts, drawing water containing dirt from the dirt collection tank 7 through the second water circulation pipe. When this water passes through the second filter assembly, the dirt is also filtered out. Then it merges with the filtered water in the first water circulation pipe and returns to the spent fuel water tank 19, realizing water recycling and effective separation of dirt. After the above treatment, the dirt and water are effectively separated. During the cleaning of the dirt on the surface of the fuel components, the radioactivity level in the spent fuel water tank will not increase, thus preventing a chain reaction.

[0025] In some embodiments, the dirt collection tank 7 is 0.7 meters long and 0.5 meters wide. The dirt deposition tank 8 can be freely installed and removed from the dirt collection tank 7.

[0026] Please refer to Figures 1 and 2. A chemical purifier 18 is also installed on the first water circulation pipe. The chemical purifier 18 is located at the outlet end where the first water circulation pipe and the second water circulation pipe meet. The chemical purifier 18 is used to purify the water.

[0027] In this embodiment, the chemical purifier 18 can further purify the water after it has been filtered by the first filter assembly and the second filter assembly, removing any trace amounts of radioactive substances and other impurities that may remain in the water, ensuring that the water quality returned to the spent fuel pool 19 meets safety standards, and further reducing the risk of radioactive contamination.

[0028] Furthermore, the first filter assembly includes at least one first filter, which is connected to the first water circulation pipe; the second filter assembly includes at least one second filter, which is connected to the second water circulation pipe.

[0029] The number of the first and second filters can be flexibly configured according to actual cleaning needs and the amount of dirt. When the amount of dirt is large or the filtration accuracy requirement is high, the number of the first and second filters can be increased to adopt a multi-stage filtration method, improving the filtration effect and ensuring more thorough removal of dirt and radioactive substances from the water. Conversely, when the amount of dirt is small or the filtration accuracy requirement is relatively low, the number of filters can be appropriately reduced to lower equipment costs and operating energy consumption. This flexible configuration allows the ultrasonic cleaning and descaling device to adapt to the needs of different working conditions, improving the versatility and practicality of the device.

[0030] Furthermore, a first inlet filter is provided at one end of the first water circulation pipe connected to the dirt collection tank 7. The first inlet filter is used to filter the dirt removed by ultrasonic cleaning, so that the dirt remains in the dirt collection tank 7. A second inlet filter is provided at one end of the second water circulation pipe connected to the dirt collection tank 7. The second inlet filter is used to filter the dirt removed by ultrasonic cleaning, so that the dirt remains in the dirt collection tank 7.

[0031] Specifically, the first and second inlet filters perform preliminary filtration. As water flows from the dirt collection tank into the first and second water circulation pipes, they intercept most of the larger dirt particles, preventing them from entering subsequent filtration stages and the circulation system. This reduces the filtration burden on the first and second filter assemblies and improves the stability and reliability of the entire water circulation system. Furthermore, the installation of these two inlet filters prevents dirt from accumulating in the pipes, reducing equipment failures and maintenance costs caused by dirt clogging, and ensuring the continuous and efficient operation of the device.

[0032] Referring to Figure 1, in some possible implementations, the component cleaning mechanism may include: a fuel assembly hoisting mechanism 1, a component cleaning cylinder 6, and an ultrasonic generator 4. The fuel assembly hoisting mechanism 1 is used to hoist and move the fuel assembly; the component cleaning cylinder 6 is located below the fuel assembly hoisting mechanism 1 and is used to accommodate and clean the fuel assembly. The dirt collection tank 7 is located on the lower side of the component cleaning cylinder 6 and communicates with the component cleaning cylinder 6; the ultrasonic generator 4 is located on the inner wall of the component cleaning cylinder 6 and is capable of moving along the direction in which the component cleaning cylinder 6 extends.

[0033] In this embodiment, the fuel assembly hoisting mechanism 1 accurately hoists the fuel assembly into the assembly cleaning cylinder 6. The ultrasonic generator 4 moves along the direction extending from the assembly cleaning cylinder 6, uniformly emitting ultrasonic waves to all parts of the fuel assembly. The ultrasonic waves remove dirt from the surface of the fuel assembly, allowing it to flow with the water into the dirt collection tank 7 below. This cleaning method effectively removes stubborn dirt, improves the cleaning effect, and does not damage the fuel assembly. Furthermore, the movable design of the ultrasonic generator 4 makes the cleaning process more flexible, enabling the cleaning of dirt from different parts of the fuel assembly.

[0034] It should be noted that, as a preferred embodiment, the inner wall of the component cleaning cylinder 6 is provided with a groove, and the ultrasonic generator 4 is disposed in the groove. The ultrasonic generator 4 can be disposed on both the lead screw and the optical axis. The ultrasonic generator 4 is threadedly engaged with the lead screw and slidably engaged with the optical axis. The motor drives the lead screw to rotate, thereby causing the ultrasonic generator 4 to move up and down along the optical axis, thus achieving cleaning of different parts of the fuel assembly.

[0035] Furthermore, the fuel assembly hoisting mechanism 1 has a total load capacity of 1 ton. It can move freely laterally and hover at a fixed point within a range of 0 to 5 meters around the ultrasonic generator 4, and can move freely vertically and hover at a fixed point within a range of 0 to 5 meters (with the top of the assembly cleaning cylinder 6 as the base plane). The assembly cleaning cylinder 6 has a diameter of 0.5 meters and a length of 5.2 meters, which can completely accommodate the fuel assembly and ensure that the fuel assembly is completely submerged in the wastewater. The bottom of the assembly cleaning cylinder 6 has a tapered design, with a height of 0.5 meters and a diameter that gradually decreases from 0.5 meters to 0.3 meters. The ultrasonic generator 4 can move freely vertically and hover at a fixed point within a height range of 0 to 4.8 meters (with the top of the assembly cleaning cylinder 6 as the base plane) on the inner wall of the assembly cleaning cylinder 6. In addition, the ultrasonic generator 4 can generate ultrasonic frequencies from 0 to 500 Hz, and the ultrasonic wave range is 0.25 × 0.25 meters.

[0036] Please refer to Figures 1 and 2. The component cleaning mechanism may also include a weighing component 2, wherein the weighing component 2 is disposed on the fuel assembly hoisting mechanism 1 and is used to weigh the fuel assembly.

[0037] In practical operation, the weighing component 2 can accurately measure the weight of the fuel assembly when the fuel assembly hoisting mechanism 1 hoists the fuel assembly. This function has multiple benefits. First, by accurately weighing the fuel assembly, the change in mass before and after use can be understood in a timely manner, thereby determining the amount of dirt adhering to the surface of the fuel assembly and providing intuitive data for evaluating the cleaning effect. Second, for some processes with strict weight requirements, accurate weight data can ensure the safety and stability of the fuel assembly during subsequent processing and use, avoiding potential risks caused by weight deviations.

[0038] For example, the effective weighing range of the weighing component 2 is 0 to 1000 kg, and its weighing accuracy is 0.1 kg.

[0039] Please refer to Figure 1. The component cleaning mechanism may also include a chemical injection mechanism 3, wherein the chemical injection mechanism 3 is used to inject chemical agents into the surface of the fuel assembly to assist in descaling.

[0040] In this embodiment, after the fuel assembly is hoisted into the assembly cleaning cylinder 6, the chemical injection mechanism 3 begins operation. The chemical agent reacts with the dirt on the surface of the fuel assembly, altering the properties of the dirt, such as softening or decomposing it, making it easier to remove with ultrasonic waves. This cleaning method, combining chemical agents and ultrasound, fully leverages the advantages of both descaling methods, enabling more effective removal of different types of dirt and significantly improving cleaning efficiency and quality.

[0041] The chemical injection mechanism 3 injects chemical agents onto the surface of the fuel assembly at a flow rate of 0 to 3 m / s.

[0042] Please refer to Figure 1. A diversion plate 9 is provided in the dirt collection tank 7. The ends of the first water circulation pipe and the ends of the second water circulation pipe are located on both sides of the diversion plate 9, respectively.

[0043] The diversion plate 9 plays a crucial role in rationally distributing the water flow. During the cleaning process, the water flowing from the component cleaning cylinder 6 into the dirt collection tank 7 carries a large amount of dirt. The diversion plate 9 evenly directs the water flow to the inlets of the first and second water circulation pipes. This allows both water circulation systems to simultaneously and stably extract water containing dirt, achieving self-separation of accumulated scale.

[0044] In some embodiments, the angle between the diversion plate 9 and the side plate of the dirt collection tank 7 is 60°, and the length of the diversion plate 9 is two-thirds of the length of the dirt collection tank 7.

[0045] Please refer to Figure 1. The chemical injection mechanism 3 may include: a dosing tank, a peristaltic pump 20, and a connecting hose. The dosing tank is used to hold chemical agents. The peristaltic pump 20 is connected to the dosing tank through a pipe and is used to draw chemical agents from the dosing tank. The input end of the connecting hose is connected to the output end of the peristaltic pump 20, and the output end of the connecting hose is connected to the ultrasonic generator 4 and can inject chemical agents into the parts of the fuel assembly that need descaling. The connecting hose is retractable.

[0046] Specifically, the dosing tank, as a container for storing chemicals, ensures safe and stable storage, preventing leakage or deterioration. The peristaltic pump 20 precisely controls the amount of chemicals extracted, ensuring accurate dosage for each injection onto the fuel assembly surface, which is crucial for efficient chemical descaling. Insufficient chemical injection may result in inadequate reaction with the scale, affecting descaling effectiveness; excessive injection not only wastes chemicals and increases costs but may also cause unnecessary corrosion to the fuel assembly. The extendable connecting hose provides great flexibility, adjusting its length and angle according to the movement of the fuel assembly lifting mechanism 1 and the position of the ultrasonic generator 4, ensuring accurate injection of chemicals to the areas requiring descaling on the fuel assembly surface. Regardless of the fuel assembly's position within the assembly cleaning cylinder 6, the connecting hose precisely delivers the chemicals to the target location, maximizing their descaling assistance and working in conjunction with ultrasonic cleaning to enhance the overall device's ability to remove scale from the fuel assembly surface.

[0047] Please refer to Figure 3. The fuel assembly hoisting mechanism 1 may include: a base 101, a fixing frame 102, and a hoisting assembly 103, wherein the fixing frame 102 is fixed on the base 101; the hoisting assembly 103 is disposed on the fixing frame 102 and is used to hoist the fuel assembly.

[0048] The base 101 serves as the fundamental support for the entire fuel assembly hoisting mechanism 1, ensuring it can withstand the weight of the fuel assemblies and various external forces without deformation or damage during long-term use. The mounting bracket 102 is securely installed on the base 101, providing a stable installation platform for the hoisting assembly 103. The hoisting assembly 103 is the part that directly contacts the fuel assemblies and performs the hoisting operation; it may include hooks, slings, electric hoists, and other equipment. These devices possess sufficient lifting capacity and precise control performance, enabling them to safely and smoothly lift, move, and accurately place the fuel assemblies into the designated position within the assembly cleaning cylinder 6. During the hoisting process, the operational precision of the hoisting assembly 103 directly affects the accuracy of the fuel assembly's installation position, thereby impacting the subsequent cleaning effect and the overall operational stability of the device.

[0049] The method of using the ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling according to this application is as follows: The fuel assembly requiring descaling and cleaning, stored in the spent fuel water tank 19, is hoisted and moved to the assembly cleaning cylinder 6 using the fuel assembly hoisting mechanism 1. During the movement, the horizontal and vertical movement speed of the fuel assembly shall not exceed 6 meters per minute, and when approaching the assembly cleaning cylinder 6, the horizontal and vertical movement speed shall not exceed 2 meters per minute. After the fuel assembly stabilizes in the assembly cleaning cylinder 6, the reading of the weighing assembly 2 is read, and the total weight W0 of the fuel assembly before cleaning is recorded. The ultrasonic generator 4 is moved to 0.5 meters above the part of the fuel assembly requiring ultrasonic cleaning, and the flow rate of the chemical injection mechanism 3 is adjusted to initially flush the part of the fuel assembly requiring cleaning with water flow. Simultaneously, the first circulation pump 17 and the second circulation pump 13 are turned on, and the rotation speeds of the first circulation pump 17 and the second circulation pump 13 are set to maintain the spent fuel water in the assembly cleaning cylinder 6 in a flowing state. Turn on the ultrasonic generator 4 and set the ultrasonic frequency to 100Hz. Slowly move the ultrasonic generator 4 to 0.5 meters below the part of the fuel assembly that needs ultrasonic cleaning, then slowly move it to 0.5 meters above the part that needs ultrasonic cleaning. Then turn off the ultrasonic generator 4. Using the flowing wastewater and the gravity of the scale, the scale removed from the fuel assembly will settle in the scale collection tank 7 for 5 minutes. Due to the difference in flow rate, heavier scale will settle in the scale deposition tank 8. The cleaned wastewater is then filtered and purified in stages before being discharged back into the spent fuel water tank for recycling. Increase the ultrasonic frequency to 200Hz and then 250Hz, repeating the above operation. After completing the final step of the above operation, again using the flow of water and the gravity of the scale, the scale removed from the fuel assembly will settle in the scale deposition tank 8 for 15 minutes. After shutting down the dual water circulation loop and waiting for the fuel assembly to stabilize, the fuel assembly is lifted out of the assembly cleaning cylinder 6. The removal of scale from the parts of the fuel assembly requiring ultrasonic cleaning is observed, and the total weight W1 of the fuel assembly after cleaning is recorded. The ultrasonic cleaning efficiency of the fuel assembly is calculated as ρ = (W0 - W1) / W0. After confirming that the fuel assembly has passed the descaling and cleaning process, the cleaned fuel assembly is placed in the spent fuel water tank. The scale deposition tank 8 is removed, and the deposited scale is collected for subsequent unified treatment. This process achieves ultrasonic cleaning of the fuel assembly while minimizing the amount of radioactive waste generated during the cleaning process and facilitating centralized disposal.

[0050] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling, characterized in that, include: Spent fuel water tank (19); component cleaning mechanism for descaling the surface of fuel components, the component cleaning mechanism being disposed within the spent fuel water tank (19); dirt collection tank (7), disposed on the bottom side of the component cleaning mechanism and communicating with the component cleaning mechanism, for collecting the dirt cleaned from the surface of the fuel components by the component cleaning mechanism; dirt deposition tank (8), disposed below the dirt collection tank (7) and communicating with the dirt collection tank (7), for depositing the dirt collected by the dirt collection tank (7); first water circulation pipe, one end connected to the top of the dirt collection tank (7), and the other end communicating with the spent fuel water tank (19). The first filter assembly is disposed on the first water circulation pipe for filtering dirt; the first circulation pump (17) is disposed on the first water circulation pipe for drawing water from the first water circulation pipe; the second water circulation pipe is connected at one end to the dirt collection tank (7) and at the other end to the first water circulation pipe, and the connection between the second water circulation pipe and the first water circulation pipe is located at the output end of the first circulation pump (17); the second filter assembly is disposed on the second water circulation pipe for filtering dirt; the second circulation pump (13) is disposed on the second water circulation pipe for drawing water from the second water circulation pipe.

2. The ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling as described in claim 1, characterized in that, A chemical purifier (18) is also installed on the first water circulation pipe. The chemical purifier (18) is located at the outlet end where the first water circulation pipe and the second water circulation pipe meet. The chemical purifier (18) is used to purify the water.

3. The ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling as described in claim 1, characterized in that, The first filter assembly includes at least one first filter, which is connected to the first water circulation pipe; the second filter assembly includes at least one second filter, which is connected to the second water circulation pipe.

4. The ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling according to claim 1, characterized in that, A first inlet filter is provided at one end of the first water circulation pipe connected to the dirt collection tank (7). The first inlet filter is used to filter the dirt removed by ultrasonic cleaning, so that the dirt remains in the dirt collection tank (7). A second inlet filter is provided at one end of the second water circulation pipe connected to the dirt collection tank (7). The second inlet filter is used to filter the dirt removed by ultrasonic cleaning, so that the dirt remains in the dirt collection tank (7).

5. The ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling according to claim 1, characterized in that, The component cleaning mechanism includes: a fuel assembly hoisting mechanism (1) for hoisting and moving fuel assemblies; a component cleaning cylinder (6) located below the fuel assembly hoisting mechanism (1) for accommodating and cleaning fuel assemblies, wherein a dirt collection tank (7) is located on the lower side of the component cleaning cylinder (6) and communicates with the component cleaning cylinder (6); and an ultrasonic generator (4) located on the inner wall of the component cleaning cylinder (6) and capable of moving along the direction of extension of the component cleaning cylinder (6).

6. The ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling according to claim 5, characterized in that, The component cleaning mechanism further includes a weighing component (2), which is mounted on the fuel assembly hoisting mechanism (1) and is used to weigh the fuel assembly.

7. The ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling according to claim 5 or 6, characterized in that, The component cleaning mechanism also includes a chemical injection mechanism (3) for injecting chemical agents into the surface of the fuel assembly to assist in descaling.

8. The ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling according to claim 1, characterized in that, The dirt collection tank (7) is provided with a diversion plate (9), and the ends of the first water circulation pipe and the second water circulation pipe are located on both sides of the diversion plate (9).

9. The ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling according to claim 7, characterized in that, The chemical injection mechanism (3) includes: a dosing tank for holding chemical agents; a peristaltic pump (20) connected to the dosing tank via a pipe for extracting chemical agents from the dosing tank; and a connecting hose with its input end connected to the output end of the peristaltic pump (20), the output end of which is connected to the ultrasonic generator (4) and can inject chemical agents into the surface of the fuel assembly where descaling is required. The connecting hose is retractable.

10. The ultrasonic cleaning and descaling device for pressurized water reactor fuel assemblies with self-separating fouling according to claim 5, characterized in that, The fuel assembly hoisting mechanism (1) includes: a base (101); a fixing frame (102) fixed on the base (101); and a hoisting assembly (103) disposed on the fixing frame (102) for hoisting the fuel assembly.

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