A method of hot cutting of radioactive metal waste

Abstract

This invention discloses a method for thermally cutting radioactive metal waste, comprising the following steps: determining the cutting process and cutting path for the radioactive metal waste; installing a thermal cutting head; placing the radioactive metal waste into a thermal cutting device; activating a negative pressure system to create negative pressure within the negative pressure station body; performing cutting according to the set path; and transporting and collecting the cut material fragments. The negative pressure system includes a main exhaust fan, a dust filter, a radioactive aerosol filter, and an air outlet, all located outside the negative pressure station body and connected sequentially by ductwork; and an air inlet, a supply fan, an exhaust fan, an air suction port, and a pressure gauge located inside the negative pressure station body. This method for thermally cutting radioactive metal waste, through the cooperation of the negative pressure station body module and the negative pressure system, ensures that radioactivity is contained within the negative pressure station body, preventing leakage and ensuring environmental and personnel safety. It also boasts high cutting efficiency and low secondary waste volume.

Description

[0001] This application is a divisional application of the invention patent application filed on May 19, 2022, with application number 2022105529092 and invention title "A Thermal Cutting Device and Method for Radioactive Metal Waste". Technical Field

[0002] This invention belongs to the field of nuclear engineering technology, and specifically relates to a method for thermal cutting of radioactive metal waste. Background Technology

[0003] In nuclear power engineering, the main radioactive nuclear island equipment such as the reactor pressure vessel top cover, steam generator, and pressurizer are characterized by their large size, heavy weight, and thick walls. In order to reduce the volume of radioactive solid waste after decommissioning and lower disposal costs, these devices need to be cut and prepared on-site when decommissioned.

[0004] The reactor pressure vessel's top cover weighs 58 tons, has an outer diameter of 4.7 meters, a total height of nearly 3 meters, a head thickness of 170 mm, and a flange thickness of 850 mm. The steam generator has a vertical tank-like structure with an inner diameter of up to 1.5 meters, a wall thickness of up to 46 mm, and a total height of 6 meters. According to nuclear power plant decommissioning requirements, its internal U-shaped pipes and parts of the shell require cutting equipment. The pressurizer also has a vertical tank-like structure with an inner diameter of up to 1.2 meters and a wall thickness of up to 63 mm, and is generally cut and prepared as a whole.

[0005] Currently, both domestically and internationally, diamond wire sawing or waterjet cutting are commonly used to cut thick, radioactive components. These two methods have two drawbacks: 1. Slow cutting speed: For the same thickness, thermal cutting (flame cutting, plasma cutting) is 10 to 50 times faster than diamond wire sawing or waterjet cutting. 2. Large amount of secondary waste generated: After diamond wire sawing cuts radioactive equipment, the entire mechanical structure is contaminated, becoming radioactive pollutants; waterjet cutting requires adding a large amount of solid abrasive to the water, and during the cutting process, the abrasive is converted into radioactive pollutants.

[0006] Overall, the amount of secondary waste from thermal cutting (flame cutting, plasma cutting) is only about 5% of that from diamond wire sawing and waterjet cutting. However, thermal cutting of large, radioactive parts generates a large amount of radioactive particles, radioactive dust, aerosols, and other air pollutants, polluting the environment and threatening personnel safety. Summary of the Invention

[0007] In view of this, in order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a thermal cutting method for radioactive metal waste, which can safely use flame cutting or plasma cutting to cut and prepare radioactive thick and large parts, improve cutting efficiency, reduce the amount of secondary waste generated, and also solve the problem of handling radioactive particles, dust and aerosols generated by thermal cutting, ensuring environmental and personnel safety.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A thermal cutting device for radioactive metal waste includes a negative pressure station module, a negative pressure system, and a cutting and collection module. The negative pressure system provides negative pressure to the negative pressure station module and filters particles, dust, and radioactive aerosols generated during the thermal cutting of radioactive metal waste. The cutting and collection module includes a thermal cutting device. The negative pressure station module is used to hold the radioactive metal waste to be cut and the thermal cutting device. The thermal cutting device and the radioactive metal waste to be cut are placed in the negative pressure station module. The negative pressure station system provides negative pressure to the negative pressure station module and absorbs and treats the particles, dust, and radioactive aerosols generated during thermal cutting. The cutting and collection module cuts and collects the radioactive metal waste to be cut.

[0010] In the above technical solution, preferably, the negative pressure station body module includes a negative pressure station body, an air inlet window, a viewing window, and a soft curtain. A guide rail is provided at the bottom of the negative pressure station body, penetrating the negative pressure station body. A collection and transportation trolley is mounted on the guide rail. The air inlet window and the viewing window are located on the side of the negative pressure station body. The soft curtain is installed on the portion of the negative pressure station body through which the guide rail and the collection and transportation trolley pass. The air inlet window is a louver, and the soft curtain in the negative pressure station body module serves two purposes: firstly, the air inlet window is used for air intake, and the soft curtain is used for the guide rail and the collection and transportation trolley to enter and exit. Secondly, observing and confirming that the louver opens inwards and the soft curtain drifts inwards serves as one characteristic of whether the negative pressure system has been successfully started. Specifically, when the negative pressure system is working, the louver opens inwards to allow air in, and the soft curtain drifts inwards; when the negative pressure system is not working, the louver and the soft curtain close.

[0011] In the above technical solution, a further preferred embodiment is that the negative pressure station body is rectangular, comprising a top cover plate and four side plates. Adjacent side plates are bonded together with sealant. The top cover plate is also equipped with lifting lugs. The negative pressure station body contains a thermal cutting zone for cutting radioactive metal waste, where the radioactive metal waste to be cut and the thermal cutting device are placed. The negative pressure station body is rectangular, with the side plates made of color steel plates. The seams are bonded with sealant to ensure an airtight seal. An air intake louver is provided on the upper part of one side, the number of which can be flexibly set according to size, with 2-4 louvers recommended. A viewing window is provided on the color steel plate on this side, the size of which depends on the actual situation, but a minimum of 1.2M × 1.2M is recommended, for personnel to observe the working conditions inside the negative pressure station body from the outside. Additionally, two lifting lugs are provided on the top cover of the negative pressure station body, allowing the top cover to be moved away when needed, and large items to be hoisted in and out of the negative pressure station body from the top.

[0012] In a further preferred embodiment of the above technical solution, the negative pressure system includes a main exhaust fan, a dust filter, a radioactive aerosol filter, and an air outlet, all located outside the negative pressure station body and connected sequentially by air ducts; and an air inlet, a supply fan, an exhaust fan, an air intake, and multiple pressure gauges located inside the negative pressure station body. The air inlet is located at the air inlet window. The supply fan is used to supply air to the thermal cutting zone so that particles, dust, and radioactive aerosols generated from thermal cutting radioactive metal waste are blown to the inlet of the exhaust fan. The system is used to receive particles, dust, and radioactive aerosols generated in the thermal cutting zone and to supply air to the duct. The exhaust fan and the air intake are connected to the main exhaust fan via the duct. The main exhaust fan receives the particles, dust, and radioactive aerosols received by the exhaust fan and receives the air from the negative pressure station body absorbed by the air intake. One of the three pressure gauges is located in the thermal cutting zone, and the other two pressure gauges are located near the air inlet and the air intake, respectively. The supply fan and exhaust fan together create a good negative pressure space in the thermal cutting zone. The air supply source of the main exhaust fan includes two parts: the air supplied by the exhaust fan; and the air absorbed from the negative pressure station body at the air intake. The dust filter is used to filter particles and dust generated by thermal cutting in the ventilation system, and the radioactive aerosol filter is used to filter radioactive aerosols in the air, ensuring no radioactive leakage and ensuring the safety of the external environment and personnel of the negative pressure station. Multiple pressure gauges are used to observe and confirm whether their readings are negative pressure. Only after turning on the main exhaust fan, supply fan, and exhaust fan; observing and confirming that the louvers open inward to allow air in and the soft curtains drift inward; and observing and confirming that the readings of each pressure gauge are negative pressure; the completion of the above three tasks indicates that negative pressure has been formed inside the negative pressure workstation.

[0013] In a further preferred embodiment of the above technical solution, the negative pressure system further includes a combustible gas concentration monitor, a radioactive dose monitor, and multiple surveillance cameras installed within the negative pressure station body. It is recommended that 8 to 10 surveillance cameras be installed to ensure observation of equipment such as the supply fan, exhaust fan, louvers, guide rails, and cutting device within the negative pressure station body. The combustible gas concentration monitor is used to monitor the concentration of the thermal cutting gas within the negative pressure station body. Once the concentration reaches a set threshold, a concentration alarm is triggered, and the cutting equipment immediately stops operating, and the gas supply pipeline is shut off. The radioactive dose monitor continuously monitors the radioactive dose radiation level in the air within the negative pressure station body and transmits it to the personnel control platform in real time. Once the monitored value exceeds the threshold, an alarm signal is immediately issued.

[0014] In the above technical solution, further preferably, the cutting and collecting module includes a collecting device and a thermal cutting device. The thermal cutting device includes a gantry frame, an execution head mounted on the gantry frame, a thermal cutting head mounted on the execution head, and a support frame for supporting the radioactive metal waste to be cut. The gantry frame can move along the Y-axis, and the execution head can retract vertically and move along the X-axis on the gantry frame. The collecting device includes a collecting and transporting trolley and a traction guide rail. The collecting and transporting trolley is used to receive the cut material blocks after the radioactive metal waste to be cut is cut. The execution head can extend and retract vertically, and in conjunction with the gantry frame, it allows the thermal cutting head to move in the XYZ three-axis space. The support frame is used to support the parts to be cut, and is recommended to be designed with a load capacity of 70 tons, capable of supporting large components such as round, square, and plate parts. The thermal cutting head is selected based on the shape, thickness, and material of the parts to be cut, using a suitable thermal cutting process and corresponding cutting head.

[0015] In the above technical solution, and more preferably, the support frame has a central opening to form a material drop port, from which the cut material block falls onto the collection and transport trolley. The central opening of the support frame allows the cut material block to fall directly onto the collection and transport trolley at the bottom. The trolley's width encompasses the central opening of the support frame, and a guide rail pulls the trolley, allowing it to move into the negative pressure station body or transport the cut material block out of the negative pressure station body.

[0016] In the above technical solution, a further preferred embodiment is that the thermal cutting head is a flame cutting head or a plasma cutting head. A reasonable thermal cutting process and cutting path are selected based on the shape, thickness, and material of the workpiece to be cut. Generally speaking, for carbon steel parts with a thickness exceeding 60mm, flame cutting can be selected; for stainless steel and carbon steel parts with a thickness less than 60mm, plasma cutting can be selected, and thus a thermal cutting head of the appropriate specification is chosen.

[0017] In addition, the control systems of all the above equipment are integrated into a centralized control platform outside the negative pressure station body, enabling remote operation and control by personnel.

[0018] The present invention also provides a method for thermal cutting of radioactive metal waste, comprising the following steps:

[0019] Place the thermal cutting head and the radioactive metal waste to be cut; activate the negative pressure system to create negative pressure within the negative pressure station; cut the radioactive metal waste to be cut, transport and collect the fallen cutting material.

[0020] In the above technical solution, preferably:

[0021] Starting the negative pressure system includes the following steps: turning on the main exhaust fan, the supply fan, and the exhaust fan; observing and confirming that the air inlet window is opening to allow air to enter the negative pressure station body, and that the soft curtain is drifting towards the inside of the negative pressure station body; observing and confirming that the readings of each pressure gauge are negative pressure.

[0022] Due to the adoption of the above technical solutions, the advantages of this invention compared to existing technologies are as follows: The radioactive metal waste thermal cutting method of this invention, through the cooperation of the negative pressure station module and the negative pressure system, ensures that radioactivity is contained within the negative pressure station, preventing leakage and ensuring environmental and personnel safety; with the help of a video monitoring system and a centralized control system, cutting, transportation, and other operations can be performed remotely, manually, or automatically, eliminating the need for close-range manual operation and thus significantly reducing the radiation dose received by personnel; it is adaptable to various thermal cutting heads and can be applied to flame cutting and plasma cutting; the entire device can cut large radioactive components, including large nuclear power equipment such as evaporators, pressurizers, and reactor pressure vessel top covers. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a top view of the thermal cutting device for radioactive metal waste in a preferred embodiment of the present invention;

[0025] Figure 2 This is a front view of the thermal cutting device for radioactive metal waste in a preferred embodiment of the present invention;

[0026] Figure 3 This is a front view of the thermal cutting device for radioactive metal waste (cutting the top cover of a reactor pressure vessel) in a preferred embodiment of the present invention.

[0027] The components include: negative pressure station body-10, louvers-11, viewing window-12, soft curtain-13, hanging lugs-14, main exhaust fan-20, air duct-21, dust filter-22A, radioactive aerosol filter-22B, monitoring camera-23, combustible gas concentration monitor-24, air supply fan-25A, exhaust fan-25B, radioactive dose monitor-26, first pressure gauge-27A, second pressure gauge-27B, third pressure gauge-27C, air outlet-28, air intake-29, gantry frame-30, actuator head-31, support frame-32, thermal cutting head-33, collection and transportation trolley-34, traction guide rail-35, thermal cutting area-40, and reactor pressure vessel top cover-50. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of the present invention, 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0029] Example 1: A thermal cutting device for radioactive metal waste

[0030] See attached document Figure 1 and Figure 2 The radioactive metal waste thermal cutting device of this embodiment includes a negative pressure station main module, a negative pressure system, and a cutting and collection module. The cutting and collection module includes a thermal cutting device and a collection device.

[0031] The negative pressure station module includes a negative pressure station body 10, louvers 11, viewing windows 12, soft curtains 13, and hanging lugs 14. The negative pressure station body 10 is rectangular, including a top cover and four side panels. A thermal cutting zone 40 for cutting radioactive metal waste is located inside the negative pressure station body 10. The radioactive metal waste to be cut and the thermal cutting device are placed in the thermal cutting zone 40. The negative pressure station body 10 is constructed from four corrugated steel plates, with the seams between adjacent side panels sealed with sealant to ensure an airtight seal. Two louvers 11 are installed at the top of one side panel. The number of louvers 11 can be flexibly adjusted according to size, with 2-4 louvers recommended. A viewing window 12 is installed on the corrugated steel plate on this side, the size of which depends on the actual situation, but a minimum of 1.2m × 1.2m is recommended, for personnel to observe the working conditions inside the negative pressure station body 10 from the outside. A through guide rail 35 is installed at the bottom of the negative pressure station body 10. A collection and transport trolley 34 is mounted on the guide rail 35. A soft curtain 13 is installed on the part of the negative pressure station body 10 through which the guide rail 35 and the collection and transport trolley 34 pass. Two lifting lugs 14 are installed on the top cover plate. When needed, the top cover plate can be adjusted to allow large items to be hoisted in and out of the negative pressure station body 10 from the top. The negative pressure station body 10 is equipped with louvers 11 and soft curtains 13. On the one hand, the louvers 11 are used for air intake, and the soft curtains 13 are used for the entry and exit of the guide rail 35 and the collection and transport trolley 34. On the other hand, observing whether the louvers 11 are opening inward to allow air intake and the soft curtains 13 are drifting inward is one of the characteristics to confirm whether the negative pressure system has been successfully started. Specifically, when the negative pressure system is working, the louvers 11 open inward to allow air intake, and the soft curtains 13 drift inward. When the negative pressure system is not working, the louvers 11 and the soft curtains 13 close.

[0032] The negative pressure system includes: main exhaust fan 20, duct 21, dust filter 22A, radioactive aerosol filter 22B, monitoring camera 23, combustible gas concentration monitor 24, air inlet, supply fan 25A, exhaust fan 25B, radioactive dose monitor 26, first pressure gauge 27A, second pressure gauge 27B, third pressure gauge 27C, air outlet 28, and air intake 29. The main exhaust fan 20, dust filter 22A, radioactive aerosol filter 22B, and air outlet 28 are located outside the negative pressure station body 10 and are connected in sequence through air duct 21. The monitoring camera 23, combustible gas concentration monitor 24, air inlet, air supply fan 25A, exhaust fan 25B, radioactive dose monitor 26, air intake 29, first pressure gauge 27A, second pressure gauge 27B, and third pressure gauge 27C are located inside the negative pressure station body 10. The first pressure gauge 27A is located in the thermal cutting zone 40, the second pressure gauge 27B is close to the air inlet, and the third pressure gauge 27C is close to the air intake 29.

[0033] The supply fan 25A directly supplies air to the hot cutting zone 40, forcibly blowing the particles, dust, and radioactive aerosols generated during cutting to the inlet of the exhaust fan 25B. The exhaust fan 25B receives the air supplied by the supply fan 25A and the particles, dust, and radioactive aerosols generated in the hot cutting zone 40, and supplies the air to the ventilation duct 21. The supply fan 25A and the exhaust fan 25B together establish a good negative pressure space for the hot cutting zone 40. The air supply source of the main exhaust fan 20 includes two parts: (1) the air supplied by the exhaust fan 25B; (2) the air drawn from the air intake 29 into the negative pressure station body 10. The dust filter 22A is used to filter the particles and dust generated during hot cutting, and the radioactive aerosol filter 22B is used to filter the radioactive aerosols in the air, ensuring no radioactive leakage and ensuring the safety of the external environment and personnel of the negative pressure station. It is recommended to install 8 to 10 surveillance cameras 23 to ensure observation of the air supply fan 25A, exhaust fan 25B, louvers 11, guide rail 35, cutting device, and radioactive metal waste to be cut in the negative pressure station body 10. A combustible gas concentration monitor 24 monitors the concentration of the thermal cutting gas inside the negative pressure station body 10. Once the concentration reaches the set threshold, a concentration alarm will be triggered, and the cutting equipment will immediately stop working, and the gas supply pipeline will be shut off. A radioactive dose monitor 26 continuously monitors the radioactive dose radiation level in the air inside the negative pressure station body 10 and transmits it to the personnel control platform in real time. Once the monitored value exceeds the threshold, an alarm signal will be issued immediately.

[0034] The negative pressure system is started as follows: (1) Turn on the main exhaust fan 20, the supply fan 25A, and the exhaust fan 25B; (2) Observe and confirm that the louvers 11 are open inward to allow air in, and the soft curtain 13 is drifting inward; (3) Observe and confirm that the readings of the first pressure gauge 27A, the second pressure gauge 27B, and the third pressure gauge 27C are negative pressure. The completion of the above three tasks indicates that negative pressure has been formed inside the negative pressure workstation body 10. It is recommended that the pressure value inside the negative pressure workstation body 10 be more than 3000Pa lower than atmospheric pressure, and the air circulation rate inside the negative pressure workstation body 10 be 10 times / hour.

[0035] The cutting and collection module includes a collection device and a thermal cutting device. Specifically, the thermal cutting device includes a gantry 30, an execution head 31 mounted on the gantry 30, a thermal cutting head 33 mounted on the execution head 31, and a support frame 32 for supporting the radioactive metal waste to be cut. The collection device includes a collection and transport trolley 34 and a traction guide rail 35. The gantry 30 is the traveling mechanism for the thermal cutting head 33 to perform cutting. The gantry 30 can move along the Y-axis. The actuator head 31 can retract vertically and move along the X-axis on the gantry 30. The actuator head 31 can extend and retract vertically. In conjunction with the gantry 30, the thermal cutting head 33 can travel in the XYZ three-axis space. The support frame 32 is used to support the workpiece to be cut. It is recommended to design a load capacity of 70 tons, which can carry large components such as round, square, and plate parts. The support frame 32 has an open middle section, and the cut pieces of radioactive metal waste fall directly to the collection and transportation trolley 34 at the bottom. The appropriate thermal cutting process and corresponding thermal cutting head 33 are selected according to the shape, thickness, and material of the workpiece to be cut. Specifically, for carbon steel parts with a thickness of more than 60mm, flame cutting process and flame cutting head can be selected; for stainless steel and carbon steel parts with a thickness of less than 60mm, plasma cutting process and plasma cutting head can be selected. The collection and transport trolley 34 is used to receive the cut material blocks. Its width covers the hollow area of ​​the support frame 32. The guide rail 35 pulls the collection and transport trolley 34 to move, which can send the collection and transport trolley 34 into the negative pressure station body 10, or transport the cut material blocks out of the negative pressure station body 10. The control systems of all the above equipment are integrated into the centralized control platform outside the negative pressure station, realizing remote operation and control by personnel.

[0036] See Figure 3 This is a front view of the radioactive metal waste thermal cutting device used to cut the reactor pressure vessel top cover 50 in this embodiment. Since the reactor pressure vessel top cover has a total weight of 58 tons, an outer diameter of 4.7 meters, a total height of nearly 3 meters, a head thickness of 170 mm, and a flange thickness of 850 mm, flame cutting technology is selected when cutting it, and the thermal cutting head 33 is selected as a flame cutting head.

[0037] Example 2: A method for thermal cutting radioactive metal waste

[0038] This embodiment provides a thermal cutting method for radioactive metal waste according to Embodiment 1, including: placing a thermal cutting head and the radioactive metal waste to be cut; activating a negative pressure system to create negative pressure within the negative pressure station body; cutting the radioactive metal waste to be cut; and transporting and collecting the fallen cutting blocks.

[0039] Specifically, the steps include:

[0040] (1) Formulate the cutting process and cutting path for radioactive metal parts: Select a reasonable thermal cutting process and cutting path according to the shape, thickness and material of the part to be cut. Generally speaking, for carbon steel parts with a thickness of more than 60mm, flame cutting process can be selected; for stainless steel and carbon steel parts with a thickness of less than 60mm, plasma cutting process can be selected.

[0041] (2) Install the appropriate thermal cutting head and set the cutting head travel program according to the path: Select the appropriate thermal cutting head (flame cutting head or plasma cutting head), install it on the actuator head 31, and set the travel program of the gantry 30 and the actuator head 31 in the central control system according to the preset cutting path. In this embodiment, the cutting head is used to cut the top cover of the reactor pressure vessel, and a flame cutting head is selected and installed on the actuator head 31.

[0042] (3) Place the radioactive metal parts to be cut onto the support frame 32: hoist the radioactive metal waste to be cut (in this embodiment, the top cover of the reactor pressure vessel) onto the support frame 32, hoist the top cover plate of the negative pressure station body 10 into place, and close the negative pressure station body 10.

[0043] (4) Start the negative pressure system to form negative pressure in the workstation: Start the negative pressure system as required, turn on the main exhaust fan 20, the supply fan 25A, and the exhaust fan 25B; observe that the louvers 11 open inward to allow air in, and the soft curtain 13 drifts inward; the readings of the first pressure gauge 27A, the second pressure gauge 27B, and the third pressure gauge 27C are negative pressure. Confirm that negative pressure has been formed in the station.

[0044] (5) Cutting along a predetermined path: The operator remotely starts the thermal cutting head 33, operates the gantry 30 and the execution head 31 to cut along a predetermined path.

[0045] (6) Transporting and collecting the cut pieces that have fallen off the cutting: The bottom collection and transport trolley 34 receives the corresponding cut pieces and transports them out of the negative pressure station body 10 in a timely manner.

[0046] The thermal cutting method for radioactive metal waste in this embodiment solves the problem of handling radioactive particles, dust, and aerosols. It can safely use flame cutting or plasma cutting to cut and prepare large radioactive components, improving cutting efficiency and reducing the amount of secondary waste generated.

[0047] To further understand the solution in this application, the following are implementation examples and comparative examples of specific applications:

[0048] Application Case: The top cover of a reactor pressure vessel weighs 58 tons, has an outer diameter of 4.7 meters, a total height of nearly 3 meters, a head thickness of 170 mm, and a flange thickness of 850 mm. The radioactive metal waste thermal cutting device from Example 1, combined with the radioactive metal waste thermal cutting method from Example 2, is used for cutting. A flame thermal cutting head is selected as the thermal cutting head.

[0049] Comparative Case 1: The top cover of the reactor pressure vessel weighs 58 tons, has an outer diameter of 4.7 meters, a total height of nearly 3 meters, a head thickness of 170 mm, and a flange thickness of 850 mm. It was cut using a traditional diamond wire saw method.

[0050] Comparative Case 2: The top cover of the reactor pressure vessel weighs 58 tons, has an outer diameter of 4.7 meters, a total height of nearly 3 meters, a head thickness of 170 mm, and a flange thickness of 850 mm. It was cut using a traditional waterjet cutting method.

[0051] Table 1. Parameters and test results for application cases and comparison cases.

[0052] Application Cases 300 hours 5 tons Comparison Case 1 1500 hours 20 tons Comparison Case 2 2500 hours 300 tons

[0053] The test results in Table 1 show that the cutting time in the application case is greatly shortened and the cutting efficiency is high, only 1 / 5 to 1 / 8 of that in the comparison case. The secondary waste production is very low, only 1 / 4 to 1 / 60 of that in the comparison case.

[0054] The radioactive metal waste thermal cutting device of this invention, through the cooperation of the negative pressure station main module and the negative pressure system, ensures that radioactivity is contained within the negative pressure station and will not leak, thus ensuring environmental and personnel safety. With the help of a video monitoring system and a centralized control system, cutting, transportation and other operations can be performed remotely, manually or automatically, without the need for close-range manual operation, thereby significantly reducing the radiation dose to personnel. It is compatible with various thermal cutting heads and can be applied to flame cutting and plasma cutting. The entire device can cut large radioactive components, including large nuclear power equipment such as evaporators, pressurizers, and reactor pressure vessel top covers.

[0055] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for thermally cutting radioactive metal waste, characterized in that, Includes the following steps: Develop the cutting process and cutting path for radioactive metal waste; install the thermal cutting head; place the radioactive metal waste into the radioactive metal waste thermal cutting device; The negative pressure system is activated, creating negative pressure within the negative pressure station; cutting is then carried out according to the set path; the cut material pieces are transported out and collected. The radioactive metal waste thermal cutting device includes a negative pressure station main module, a negative pressure system, and a cutting and collection module. The negative pressure system provides negative pressure to the negative pressure station main module and filters particles, dust, and radioactive aerosols generated during the thermal cutting of radioactive metal waste. The negative pressure station main module includes a negative pressure station body and an air inlet. The negative pressure system includes a main exhaust fan, a dust filter, a radioactive aerosol filter, and an air outlet, all connected sequentially outside the negative pressure station body via ductwork. Inside the negative pressure station body are an air inlet, a supply fan, an exhaust fan, an air suction port, and a pressure gauge. The air inlet is located at the air inlet window. The blower and the exhaust fan are respectively located on opposite sides of the bottom of the hot cutting zone; the blower is used to supply air to the hot cutting zone so that the particles, dust and radioactive aerosols generated from the hot cutting of radioactive metal waste are blown to the inlet of the exhaust fan; the exhaust fan is used to receive the particles, dust and radioactive aerosols generated in the hot cutting zone and to supply air to the duct; the exhaust fan and the air inlet are respectively connected to the main exhaust fan through the duct; the main exhaust fan is used to receive the particles, dust and radioactive aerosols received by the exhaust fan and to receive the air inside the negative pressure station body absorbed by the air inlet; Starting the negative pressure system includes the following steps: turning on the main exhaust fan, the supply fan, and the exhaust fan; observing and confirming that the air inlet window is opening to allow air to enter the negative pressure station body, and that the soft curtain is drifting towards the inside of the negative pressure station body; observing and confirming that the readings of each pressure gauge are negative pressure; after starting, the pressure value inside the negative pressure station body is more than 3000Pa lower than atmospheric pressure. The negative pressure station main body module includes a soft curtain, which is used to observe and confirm whether the negative pressure system has been successfully started. The negative pressure station main body is equipped with louvers and a soft curtain. The louvers are used for air intake, and the soft curtain is used for the entry and exit of the guide rail and the collection and transportation trolley. Observing and confirming that the louvers are air intake inward and the soft curtain is drifting inward is one of the characteristics of whether the negative pressure system has been successfully started. When the negative pressure system is working, the louvers open inward to allow air in, and the soft curtain drifts inward. When the negative pressure system is not working, the louvers and soft curtain close. The cutting and collecting module includes a collecting device, which includes a collecting and transporting trolley and a traction guide rail. The collecting and transporting trolley is used to receive the cut material blocks after the radioactive metal waste has been cut. The support frame has a gap in the middle to form a material drop port, from which the cut material blocks fall to the collection and transportation trolley; the traction guide rail passes through the bottom of the negative pressure station body, and the collection and transportation trolley is installed on the traction guide rail; the soft curtain is installed on the part of the negative pressure station body that allows the traction guide rail and the collection and transportation trolley to pass through; the soft curtain is used for the entry and exit of the traction guide rail and the collection and transportation trolley. The negative pressure station main body module includes lifting lugs installed on the top cover plate, which are used to move the top cover plate away and lift large items from the top of the negative pressure station; There are three pressure gauges. One of the pressure gauges is located in the thermal cutting zone, and the other two pressure gauges are located near the air inlet and the air suction port, respectively.

2. The thermal cutting method according to claim 1, characterized in that, For carbon steel parts with a thickness exceeding 60mm, flame cutting is selected; for stainless steel and carbon steel parts with a thickness less than 60mm, plasma cutting is selected.

3. The thermal cutting method according to claim 1, characterized in that, The negative pressure system also includes a combustible gas concentration monitor, a radioactive dose monitor, and multiple surveillance cameras installed in the negative pressure station body.

4. The thermal cutting method according to claim 1, characterized in that, The thermal cutting head is either a flame cutting head or a plasma cutting head.

5. The thermal cutting method according to claim 1, characterized in that, The radioactive metal waste is a steam generator, pressurizer, or reactor pressure vessel top cover.

6. The thermal cutting method according to any one of claims 1-5, characterized in that, The cutting and collecting module includes a thermal cutting device, which includes a gantry frame, an actuator head mounted on the gantry frame, a thermal cutting head mounted on the actuator head, and a support frame for supporting the radioactive metal waste to be cut. The gantry frame can move along the Y-axis, and the actuator head can retract vertically and move along the X-axis on the gantry frame.

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