RU2029398C1 - Method and device for dismounting nuclear reactors - Google Patents

Abstract

FIELD: mechanics. SUBSTANCE: device for dismounting case of the reactor has support construction inside which the carrier rod is fixed; the rod has tip and windows made at lower part of the rod. Platform is provided with rotation drive and peripheral faceplate which are disposed onto the rotatable rod. There are instrumental rotary heads in radial grooves of the faceplate; heads are provided with cutting tool. Gripping unit of the elevator is mounted in internal space of carrier rod for movement along the total length of the rod and take product of cutting. Manipulator is mounted onto external surface of the rod; the manipulator interacts with rotatable head and container of tools which is disposed onto the support construction. Transportation facility and unit for lifting platform are mounted onto the support construction as well. Platform has protecting housing and centering unit. EFFECT: improved efficiency; improved safety of mounting. 2 cl, 6 dwg

Description

 The invention relates to nuclear energy and can be used in the dismantling of highly active equipment. An integral part of the dismantling complex is the cutting of the reactor vessel into separate parts, fragments, which is carried out mechanically, for example, with saws, disk cutters, turning tools, etc., or thermal, for example, gas cutting, plasma, electrospark, etc. Devices have been developed by which these fragmentation methods are performed.

 A known method of dismantling nuclear reactors [1], in which using an oxygen-acetylene cutter, the equipment is divided into parts, packaged and removed from the premises. Operations are carried out using remotely controlled equipment. The work is carried out using air purification systems under strict control and inside a room equipped with bioprotection.

 The disadvantages of the method are the use of complex equipment, the allocation of a large amount of secondary radioactive waste (RAW), the need for further processing.

 Closest to the invention, the technical solution is the method implemented during the dismantling of the WAGR reactor [2]. For fragmentation of equipment and metal structures using oxygen-propane cutting by plasma cutters placed inside the reactor vessel. Gases and radioactive dust emitted during cutting are captured by filters. Dismantled fragments are set up and transported for further processing and disposal.

 When implementing the method, a large amount of secondary radioactive waste is formed. When using thermal cutting, a lot of smoke is generated, which should be cleaned, filtered from particles at the submicron level, which requires additional expensive systems and devices for gas localization and purification. In addition, complex aggregates and devices are used, a large range of devices, grippers and containers is needed due to the different configuration and mass of dismantled fragments, additional equipment is required at processing plants.

 The purpose of the invention is to increase the efficiency and safety of dismantling contaminated equipment.

 The goal is achieved by the fact that dismantling is carried out by a continuous process of cutting the reactor vessel along the end surface from top to bottom into the element chips sprinkled on the bottom of the vessel, and remove it through the internal cavity of the support rod holding the reactor vessel.

 If you fix the position of the reactor vessel in the shaft space so that when the standard attachment points are removed, the vessel does not change its position, then it can be fragmented by cutting, for example, milling continuously from the end surface from top to bottom. With all known methods and devices, this method is not possible.

 There is no known way to dismantle contaminated equipment from available sources of information, and experts are delighted by the unexpectedness, simplicity and efficiency, reliability and practical feasibility of the proposed idea in relation to this equipment.

 The known methods of dismantling, in addition to the method of disposing of equipment in an unassembled form, have a common drawback: low efficiency resulting from the dismantling technology, which involves disintegration of equipment into primary enlarged fragments, which are then sent for subsequent grinding to sizes and conditions suitable for special processing of radioactive materials . In addition, the technology and design of the devices involve the sequence of operations of cutting, transportation, replacement of the cutting tool, moving devices from one working area to the next.

 A device is known (ed. St. USSR N 1362339, class G 21 F 7/06, 12.26.85) containing a cutting machine, a cutting shaft, a clamping device, a manipulator, a crane moving along the camera, and a cork located coaxially with the clamping device. In the cutting shaft, a lift is moved, on which a rotary faceplate is placed, on the plane of which the workpiece is installed. The clamping device is made in the form of a set of partially entering each other cartridges with clamping cams connected by gears with a drive.

 The device operates as follows. Using the manipulator, depending on the size of the workpiece, one, two or three cartridges are installed. When cutting the product, the separated fragment of the nuclear reactor is mounted on the rotary faceplate of the elevator and fixed in the clamping device. Using a block system, the lift is set to the required height near the cutting machine. Cutting the fragment is carried out by rotating the cutting machine tool, its radial feed and rotation of the clamping device. After cutting, one part of the fragment is taken to the side with a crane, and the remaining part is lifted to the next required height by a hoist and the cutting operation is repeated. The cut parts are removed from the chamber using a crane through an opening closed by a stopper.

 The disadvantage of this device is the low efficiency caused by the preliminary operation of cutting the reactor vessel into fragments that enter the cutting device, as well as the time-consuming operation of installing the fragment (having a complex geometric shape) in the clamping device.

 A known machine for dismembering the reactor vessel (News of Science and Technology, ser. Nuclear Power Engineering, issue 6, pp. 42-44, Fig. 9, 10, M., VINITI, 1990), containing supports on which the cutting device is mounted, having a rotating segment in which the cutting heads move in the radial direction. To ensure the alignment of the cutting device and the reactor vessel on the supports are centering devices. To deliver the device to the working area, the supports are connected with a lifting mechanism using flexible elements. As a cutting tool, turning tools installed in cutting heads are used.

 The device operates as follows. Using the lifting mechanism, the device descends to the bottom of the reactor vessel, the centering devices install the cutting device coaxially with the reactor vessel. The cutting device rotates the segment around the vertical axis of the body and at the same time moves the cutting heads with cutters to the reactor vessel, thereby carrying out the process of fragmentation of the body. Fragmentation products are rings of a certain height, which are transported for further grinding using special vehicles. Thus, this device allows the fragmentation of the reactor vessel manufacturer, only starting from the bottom of the vessel.

 The disadvantage of this device is that the product of fragmentation are large-sized rings with a large weight, for the transportation of which special handling and transport devices with a large carrying capacity are necessary. In addition, the primary fragments (rings) require subsequent grinding, the implementation of which requires special equipment and a room. These shortcomings reduce the efficiency of dismantling. The disadvantages of this device include the radiation hazard of the fragmentation and transportation process, since in the fragmentation process, in addition to the primary fragments (rings), chips are also produced, which, after the bottom sections, scatter in the reactor shaft, worsening the radiation situation in it and causing an additional need for collection these wastes and their disposal from the mine. Since the primary fragment (ring) has large overall dimensions and cannot be removed through the internal cavity of the remaining part of the housing, it is necessary to arrange special transport passages for transportation. Due to the large dimensions of the ring, it cannot be placed in a protective transport container, and therefore, during transportation, the radiation hazard to the operating personnel and the environment increases.

 The closest in technical essence to the claimed is a device designed for dismantling the WAGR reactor (Extending the life and decommissioning of nuclear power plants in the UK. "Nuclear Power Abroad, N 6, 1985, p. 11, UDC 621.039.0047. Energoatomizdat), comprising a supporting structure with a rotary plate, on which a supporting rod is mounted with a platform equipped with a manipulator with a cutting tool. On the lower plane of the supporting structure there is an elevator with interchangeable gripping devices, which can be lifted imodeystvovat platform supporting rod and a transport device located in a special room. The protective cover is installed in the reactor hall above the shaft reactor, separating it from the surrounding space of the reactor hall. Thus, the protective casing is a sealing element.

 The device operates as follows. The support rod is mounted inside the reactor vessel. By rotation of the rotary plate of the supporting structure and the platform of the supporting rod, the manipulator with the cutting tool is brought into the working area. The cutting tool is used to cut the reactor vessel into fragments, the dimensions of which are determined by the lifting capacity of the lifting device and the capacity of the transport containers. Moving the fragment in the vertical and horizontal directions, the lifting device feeds it to the transport device to move to the zone of further processing. Gases and radioactive radiation released during fragmentation are localized using specially constructed building structures and a protective casing.

 The disadvantage of this device is the low efficiency caused by the following features of the device. It is not possible to fragment the reactor vessel during the period when the fragment moves from the body to the transport device and when the cutting tool is replaced. The reference nodes of the reactors are located in the upper third of the vessel, which leads to a certain sequence of cutting the reactor vessel, and this necessitates a readjustment of the device, which takes a certain time due to the complex design of the device. The use of thermal cutting methods is associated with the release of gases and aerosols, which, interacting with radioactive materials, are saturated with radionuclides. This circumstance determines the presence of a system for trapping and purifying gas emissions, the productivity of which determines the intensity of the process of cutting the reactor vessel. The disadvantage of this device is also the radiation hazard to the operating personnel and the environment. In this device, a gas burner or plasma torch is used as a cutting tool. The resulting gases and aerosols carry radionuclides into rooms and systems, which increases the risk of exposure to maintenance personnel and environmental pollution.

 The aim of the invention is to increase the efficiency and safety of dismantling contaminated equipment.

 The goal is achieved in that in a device for dismantling contaminated equipment containing a support structure with a supporting rod fixed therein, equipped with a platform, a manipulator and drives for lifting and turning the platform, a lift, a transport device for removing fragmentation products and a tool magazine, the platform is equipped with a centering device installed with the ability to move along the support rod and fixation at any point, with a peripheral rotary faceplate with baffle plates, in radial guides at least two double-sided tool turning heads are installed with mounting places for cutting tools made in them, the manipulator is mounted on a support rod with the ability to move along and around it and interacting with tool turning heads and a tool magazine, the support rod is fixed in the supporting structure and made hollow, the grip of the lift is installed in the inner cavity of the rod with the ability to move along its entire height and to take the products of cutting, protruding on the bottom of the reactor vessel, and the end of the rod is equipped with a tip made with the possibility of fixing in the bottom of the reactor vessel.

 Equipping the dismantling device with a platform moving along the support rod using a platform lifting drive having a peripheral rotary faceplate with radial guides along which the tool rotary heads move allows the cutting tool to be moved during cutting simultaneously in three coordinates, which reduces the cutting time tool increases the efficiency of dismantling. Due to the continuity of the cutting process, as well as the constant direction of movement along the body, the independent operation of idling the cutting tool from one working area to another is excluded, which also increases the efficiency of dismantling.

 Equipping the device with tool turning heads having connecting places for the cutting tool allows to reduce the time required to change the tool, since the head has several places for connecting the tool, which allows one tool to be replaced while another tool is working. Combining the tool replacement operation with the fragmentation operation also increases the efficiency of dismantling the reactor vessel.

 The location of the attachment points for the cutting tool on the tool turning heads in such a way that the cutting plane is the end plane of the reactor vessel allows its fragmentation, grinding along the end surface, while the cutting process is carried out mechanically, for example, with cutters, mills, etc. The product of fragmentation is elemental chips, which are collected on the bottom of the reactor.

 The ability to process the end surface of the reactor vessel in combination with the simultaneous movement of the cutting tool in three coordinates makes the fragmentation process continuous, since it does not depend on the wall thickness of the vessel and the geometric shape of its side surfaces, which are unequal in height of the vessel, and therefore, time is not required for installation of the cutting tool relative to the surface of the housing and its settings depending on the thickness of the wall of the housing, which increases the efficiency of the dismantling process.

 Since the product of fragmentation is shavings, heavy-duty manipulators working with primary fragments, the process of transporting primary fragments for grinding, an additional operation of grinding primary fragments, which dramatically increases the dismantling efficiency by reducing the dismantling time, are excluded.

 The ability to process the end surface of the reactor vessel allows fragmentation to be conducted from top to bottom (without moving the reactor vessel at the same time), which allows the lower part of the vessel to be used as a container for collecting fragmentation products. Since the platform moves downward as the vessel height decreases, a closed volume is created inside the reactor vessel in which fragmentation products are localized, which increases the safety of dismantling operations.

 Equipping the device with a centering device allows maintaining the coaxiality of the reactor vessel and the platform during fragmentation, when the processing zone is higher or at the level of the standard support nodes of the reactor vessel. When the working processing zone is lower than the standard support nodes, the centering device in combination with the supporting rod holds the remaining part of the casing in space and relative to the cutting tool in a predetermined position, which allows the fragmentation process to be carried out continuously, regardless of the position of the working working zone relative to the standard supporting nodes of the reactor vessel , i.e. to exclude the time of relocation and adjustment of the dismantling device, which increases the efficiency of dismantling.

 Equipping the platform with baffle plates eliminates the spread of fragmentation products outside the reactor vessel, i.e. the baffle screen is a limiter of the flight path of the fragmentation products.

 Equipping the support rod with a tip at the bottom ensures alignment of the dismantling device and the reactor vessel. In addition, in combination with a centering device, the tip holds the reactor vessel in space in a predetermined position when the processing zone is below the standard support nodes of the vessel. Thus, the tip allows for the fragmentation of the reactor vessel continuously, regardless of the location of the processing zone relative to the standard support nodes of the vessel, which increases the efficiency of dismantling.

 Placing the grip of the lift in the inner cavity of the carrier rod allows you to localize the transport path of the fragmentation products during their lifting, which eliminates spillage and loss of fragmentation products, which increases the safety of dismantling.

 The presence of windows in the walls of the lower part of the support rod allows the fragmentation products to accumulate directly under the grip of the lift. Thus, the processes of transportation and accumulation of fragmentation products are combined in time, which increases the efficiency of dismantling.

 Equipping the device with a manipulator allows you to change the cutting tool without stopping the fragmentation process. A failed cutting tool with the help of a tool turning head is removed from the working area with the simultaneous entry of a new cutting tool into it. The fragmentation process continues with a new tool, and at that time another failed tool is picked up by the manipulator, transported by it to the tool magazine, replaced with a new one, which is transported by the manipulator to the tool turning head and installed in it. Thus, equipment downtime associated with tool replacement is eliminated, which increases the efficiency of dismantling.

 In FIG. 1 shows a device for dismantling a reactor vessel in its initial state; in FIG. 2 - the same after passing the standard support nodes of the reactor vessel; in FIG. 3 - interaction of the manipulator with the tool turning head; in FIG. 4 shows a platform, a top view; in FIG. Figures 5 and 6 show the capture of the bottom of the reactor vessel by a supporting rod.

 The device for dismantling the reactor vessel contains a support structure 1, in which a support rod 2 is fixed, having a tip 3 and windows 4. A platform 5 is moved along the support rod 2 with a platform rotation drive 6 and a peripheral rotary faceplate 7, in which radial grooves 8 are moved heads 9 with a cutting tool 10. In the inner cavity of the support rod 2, the gripper 11 of the elevator 12 is moved, and the manipulator 13, which interacts with the instrumental turning ball, moves along the outer surface a tab 9 and a tool magazine 14 located on a supporting structure 1 on which a transport device 15 and a platform lifting device 16 are mounted. The platform 5 has fender shields 17 and a centering device 18.

 A device for dismantling the reactor vessel as follows.

 During preparation of the reactor vessel for dismantling, a hole for the tip 3 is made in its bottom. On the floor of the central hall, a support structure 1 is mounted coaxially with the reactor body with a support rod 2, which is fixed with its tip 3 in the reactor bottom. Using the centering device 18, the support rod 2 is fixed coaxially with the reactor vessel.

 The platform lifting device 16 lowers the platform 5 until the cutting tool 10 touches the reactor vessel. The tool turning heads 9 are turned on and the cutting tool 10 starts the process of fragmentation of the reactor vessel. By moving the tool rotary heads 9 along the guides 8 of the rotary faceplate 7 and the platform 5, the end surface of the reactor vessel is processed around the entire circumference. In this case, due to the choice of the direction of rotation of the cutting tool 10 and the rotary faceplate 7, as well as the presence of baffle plates 17, localization of the fragmentation products inside the reactor vessel is ensured.

 If it is possible to conduct the fragmentation process continuously from top to bottom and the product of fragmentation is chips, rather than large parts, then the remaining part of the body can be used as a chip collection from which it can be removed using a special vehicle. Since the chips are not scattered throughout the mine space, but are collected in the reactor vessel and removed through a closed channel, i.e. inside the rod, which also eliminates the spread of shavings in the mine, the proposed method of fragmentation increases the safety of dismantling. Since the bottom of the reactor vessel is elliptical, the fragmentation products are scattered through the windows 4 into the inner cavity of the carrier rod 2 under the capture 11 of the lift 12. The capture, having taken a certain part of the fragmentation products, raises it in the inner cavity of the carrier rod 2 and transfers the products to the upper point fragmentation to a transport device 15, which delivers fragmentation products to subsequent operations of special processing of radioactive materials. When the processing zone falls below the standard support nodes of the reactor vessel, the remaining part of the vessel is prevented from vertical movements by the tip 3 of the support rod 2, and from lateral displacements by a centering device 18, which is connected with the support rod.

 The cutting process and transportation of cutting products are not interconnected, i.e. the cutting process is continuous.

 If it becomes necessary to change the cutting tool 10, it is diverted from the surface to be machined by the tool turning head 9, which rotates the tool to move the new tool into the processing zone, and the failed tool is fed into the area served by the manipulator 13. The manipulator removes the cutting tool 10 from the tool turning heads 9 and lifts it to the tool store 14 located on the supporting structure 1. The manipulator 13 sets the substandard tool in the magician John 14, takes a new and delivers it to the tool swivel head 9 and sets the tool to free the lashing place. By using the entire cutting tool, the tool magazine is replaced with another.

Claims (3)

 METHOD FOR DEMOUNTING NUCLEAR REACTORS AND DEVICE FOR ITS IMPLEMENTATION.  1. The method of dismantling nuclear reactors, including placing a support structure over the reactor shaft, installing a support rod equipped with a platform with a cutting tool in the reactor vessel, securing the upper end of the support rod in the support structure, moving the platform to the cutting zone and cutting the body into fragments, followed by their removal, characterized in that the lower end of the carrier rod is fixed in the center of the bottom of the reactor vessel and the carrier rod is fixed coaxially with the reactor vessel by a centering device that is moved along the support rod, moreover, fragmentation is carried out by a continuous process of cutting the end surface of the housing from top to bottom, and the elemental chips falling on the bottom of the housing are removed through a channel made inside the support rod.  2. A device for dismantling nuclear reactors, comprising a support structure placed above the shaft with a support rod fixed therein, equipped with a platform, a manipulator and a cutting tool, platform lifting and turning drives, a lifting device, fragments with a grip, a transport device for removing them, and tool store, characterized in that the rod is equipped with a centering device installed with the ability to move along its height and fixation at any point, and the platform is equipped with a peripheral rotation a faceplate with baffle plates, in the radial guides of which at least two two-sided tool turning heads are mounted with connecting places for the cutting tool made therein, while on a support rod made hollow and provided with a tip in the lower part, it is arranged to move along and around it and interactions with rotary heads and a tool magazine, a manipulator, windows connecting the cavity of the rod and reactor shell, and the capture of the lifting device fragments installed in the inner cavity of the rod with the ability to move along its entire height and the intake of cutting products that accumulate on the bottom of the reactor vessel.

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