The method of cutting the fuel assemblies of a nuclear reactor and a cutting device for its implementation
(57) Abstract:Usage: relates to methods and devices for cutting fuel assemblies of nuclear reactors. The inventive method includes the installation of fuel assemblies in the device for cutting, cut the lower mounting means in an air atmosphere in the chamber cutting, removal of load bearing core and sequential extraction of the upper and lower beams of the fuel rods in the cooling pool, the cutting is performed with the use of a folding box consisting of two moving relative to each other parts with self-locking anchor node located at the bottom of the canister and the pressure of the emphasis placed in the upper part of the case, besides folding pencil case is further provided with a funnel with a collet grip, and a funnel and presser emphasis is made vzaimootmenyaemy. 2 S. and 4 C.p. f-crystals, 15 ill. This invention relates to a method of cutting fuel assemblies of nuclear reactors and can be used for cutting.In addition, this invention relates to cutting devices, which are used to implement the above-mentioned ways of cutting fuel assemblies of nuclear reactors.Nkawie. The first type of Assembly is used for housing the reactors, the second type of Assembly is used on channel reactors. Adebukola fuel Assembly (I. Y. Emelianov, etc. Construction of nuclear reactors. M Energoizdat, 1982, page 77, Fig. 3, 10B) consists of upper and lower lugs interconnected with tubular rods, rods and remote arrays. The cutting Assembly of this type is carried out under a layer of water that protects the operator from radiation.The Assembly of the second type, made of two bundles of fuel rods, formed fuel rods secured in the ends of the grids and interconnected spacer bars. Bundles of fuel rods placed on passing through them support rod rigidly connected with the upper and lower tips. To the upper tip attached suspension, and between bundles of fuel rods placed sleeve, excluding contact of the ends of the beams at their extension (I. Y. Emelianov, etc. Construction of nuclear reactors. M Energoizdat, 1982, pages 189-194, Fig. 7, 14). The cutting Assembly of this type is carried out in shielded cells in air atmosphere using remotely controlled equipment. A known method of cutting odnoupakovochnye the method involves cutting partially damaged or exhaust Assembly for subsequent partial replacement of fuel rods in the Assembly and install the Assembly back into the reactor. After shutting down the reactor and removing the lid of the reactor fuel Assembly is moved inside the tank reactor is installed in a transport container, transfer transport the container from a vertical to a horizontal position, move the container in a horizontal position from the tank reactor pool storage adjacent to the tank reactor. Then the transport container is moved from horizontal to vertical. Remove the fuel Assembly from the container, turn it 180oand have the rear end up, remove the lower tip Assembly for access to the ends of the fuel rod, selectively replace the fuel rods in an Assembly that is mounted on the bottom tip and guide the Assembly into the tank reactor at its new location. To perform these operations in the pool store have tilter for rotation Assembly, a device for removing the lower tip devices for transportation of spent damaged, as well as new fuel elements.Was a method of cutting odnopoloi fuel assemblies of a nuclear reactor and a device for its implementation (see US N 4522780, CL 376/260). This method provides that the spent fuel Assembly from the pool storage is SUP>oremove successively the cover of the tilter and the lower tip, and then perform the necessary manipulations c Fe. To perform these operations in the pool store have tilter to rotate the Assembly 180othe mechanism of removal of covers tilter and means for providing access to the fuel rods. This tool includes a cutting device of the weld, the suction system chip, a device for unscrewing screws.The closest in technical essence in relation to the claimed invention (method and device for implementing the method) are developed by the German firm "brown-Boveri reactor" method of cutting odnopoloi fuel assemblies of a nuclear reactor and a device for its implementation (see Nuclear Engineering International 1985, 30, 371 N, R. 19-20, 23). This method provides that the spent fuel Assembly located in the pool is transferred and installed in the container. The method provides for the possibility of repair of the fuel assemblies when the access from the upper tip, and when accessed from the bottom tip. To perform these operations on a wall of the pool set the rails on which the winch moves the main feature of the cutting device is a lift, which allows you to lift the container, rotating, tilt and drop.When this container is always under water. To secure the Assembly in the container, removed her shoes and removal installation fuel, a special tool is applied.Thus, common to all methods of cutting odnopoloi fuel Assembly is moving the Assembly to a device for tilting a fixation in this device, the handling and removal of the lower tip of the fuel Assembly to provide access to the fuel rods. All these operations are carried out under a layer of water.The cutting device for the implementation of the above operations include a device for tilting the fuel Assembly, the means for fixing the Assembly to the tilter and a tool for dismantling the tips of the fuel Assembly.It should be noted that the discussed method does not allow the cutting of the fuel Assembly, consisting of two bundles of fuel rods.Floatation device for tilting in the storage pool leads to unproductive use of its volume, the process of tilting a long time and, in addition, may cause possible damage of the I tilting is complicated construction, and given the fact that it should always be in the water, the requirement of reliability leads to additional complexity of its design.In addition, the device may not be best suited to the individual needs of the partial fuel assemblies having different external dimensions. The consequence of this is the possibility of damage to fuel assemblies for movement of the Assembly within the device when it is turned 180o.It should also be noted that in the known construction of the tilter tool clamp fuel assemblies are substantially removed from the place of cutting, which can also be a cause of possible failure of the fuel assemblies due to its bending or buckling.The design of the tilter does not take into account the fact that the fuel assemblies can have different design of the lower tip, and therefore cut the bottom of the tip relative to the lower end of the tilter can fluctuate, which would complicate the operation interval of the lower mounting means. It should also be noted that the tilter has considerable weight.The technical task of the present invention is to develop a method of cutting the fuel is Also an object of the present invention is to provide a cutting device, that would provide a simplified method of cutting.The technical task of the present invention is to provide a cutting device, which would have reduced weight characteristics. Another objective of the present invention is to provide a cutting device that allows the best way to carry out its suitability for individual differences undressed fuel assemblies.Another objective of the present invention is a device for disassembling, excluding damage to the fuel Assembly when cutting the lower mounting means.Another object of the present invention is to provide a cutting device that allows you to have a fixed position cutting the bottom of the tip relative to the lower end of the cutting device.The basis of the invention was based on the objective to develop a method for disassembling a fuel Assembly of a nuclear reactor, in which the transitions of the method of cutting at each stage was carried out with the greatest simplicity and at the same time with the greatest security, and to create a cutting device for the implementation of this method, the constructive implementation of which would allow each stage is a sample of a nuclear reactor, including installation and fixation Assembly in the device for cutting, remove the lower mounting means and removal under the water layer of the fuel rod according to the invention, the cutting of the fuel Assembly is performed with the use case, while removing the lower mounting means are produced in the camera cutting in air atmosphere, and removing the supporting rod, the upper and lower beams rods perform in the storage pool, and to remove the supporting rod and the upper beam rods foam hung in the storage pool, and before removing the lower beam rods carry out his folding, for example by the installation of a reference tool.This problem is solved in that the cutting device for implementing the method that contains the tool for installation and fixing of fuel assemblies and means for Dismounting the fuel Assembly according to the invention the means for mounting and fixing of the fuel Assembly, made in the form of a box made of two interconnected parts placed on the canister clamping means.This task is solved by the fact that the interconnected parts of the pencil case is made in the form of moving relative to each other parts, clamping means in the form of samosatene, and the case is further provided with a funnel with located along the longitudinal axis of the collet grip, thus clamping the fence and funnel made vzaimootmenyaemy and collet gripper is mounted for movement along the axis of the funnel.Preferably the lower part of the case to perform in the form of a pipe, the upper end of which has a flange located at its perimeter shaped cutters, and the upper part of the box to run in the form of a pipe and rigidly associated guide rods passing through the above-mentioned shaped cutouts flange and lower flange of the guide rods to put in the disc, covering the pipe.Suitable self-locking anchor node to perform as two unbalanced levers, provided with a base surface and the protrusions that interact with the bottom tip of the fuel Assembly.Quite reasonably self-locking anchor node positioned on a removable Cup that is connected to pipe the bottom of the canister with quick-connect.Preferably the presser emphasis to install can be moved along the axis of the nozzle upper part of the case and to provide radially spaced protrusions, interconnected OE embodiment of the device for disassembling a fuel Assembly of a nuclear reactor, carrying out the method of cutting according to the invention, provides the convenience and simplicity of operation and high reliability of all nodes means of cutting. In addition, the patented cutting tool is compact and has high versatility.In Fig. 1 the upper part of the spent fuel assemblies to be cutting, and Fig. 2 the bottom of the spent fuel assemblies to be cutting, and Fig. 3 section a-A (Fig.1 and Fig.2), and Fig. 4 a longitudinal section of the cutting device and the spent fuel assemblies; Fig. 5 - spent fuel Assembly in the camera cutting; Fig. 6 routing scheme cutting of spent fuel assemblies in the storage pool, where (a) spent fuel Assembly; transferred from the camera cutting in the pool; b) removing the supporting rod; C) removing the top of a bundle of fuel rods; g) inserting the cutting device on the supporting means for storing; d) removing low beam rods; (e) a cutting device in the initial position before receiving the next exhaust Assembly. In Fig. 7 B of Fig. 4; Fig. 8 view the pages In Fig.7; Fig. 9 the upper part of the cutting device with the clamping stop; Fig. 10 view / G Fig.9; Fig. 11 cut the lower part of the UTVA cutting with a funnel and a collet gripper; in Fig. 14 spent fuel Assembly in the cutting device, where (a) before removing the top of a bundle of fuel rods; b) before removing the lower beam rods. In Fig. 15 is a partial section of a bundle of fuel rods with introduced collet grip.The fuel Assembly 1 (Fig. 1, 2, 3) consists of two bundles of fuel rods 2 and 3, formed by the fuel rods 4 are placed in the spacer grids 5, which are rigidly connected to the frame tube 6. Through frame tube 6 passes bearing rod 7. Strung on a supporting rod 7 bundles of fuel rods 2 and 3 are fixed on the rod 7 with the upper 8 and lower 9 tips. Bundles of fuel rods 2 and 3 are separated from each other by a sleeve 10, is placed on the protruding ends of the frame tubes 6. The lower tip 9 secured to the support rod 7 through the lower mounting means 11 made in the form of screws, are secured to the support rod 7. To the upper tip 8 is attached suspension 12.Patented cutting device 13 (Fig.4) fuel assemblies 1, implements a method of cutting such Assembly according to the invention, includes a case 14 made of two interconnected parts 15 and 16, which are made in such a way that the two parts 15 and 16 can move relative to each other. The canister 14 sabago stop 18, located in the upper part 15 of the canister 14, and the funnel 19 located along the longitudinal axis of the collet gripper 20 (Fig.13). Execution clamping means in the form of the reference node 17 and clamping the stop 18, spaced at a considerable distance from each other, one of which is located near the lower end of the lower part of the canister, and the second is located at the top of the case, provide a simple and reliable fixation of spent fuel assemblies in the cutting device.In addition, the control node 17 allows you to bring the tool clamp fuel assemblies to cut. This prevents bending and possible buckling of the fuel Assembly from the cutting forces. Clamping the stop 18 and the funnel 19 is made vzaimootmenyaemy and collet grip 20 is mounted for movement along its funnel 19.According to the claimed method, cutting the spent fuel assemblies is carried out in two areas: in the camera cutting 21 (Fig.5) and in the cooling pool 22 (Fig.6). For the suspension device cutting in these areas (Fig. 9) in the upper part 15 of the canister 14 includes a flange 23 to which screws to secure the seat ring 24 with a conical annular ledge 25. The camera cutting the tool 29 (shown conventionally). In the ceiling of the cutting chamber includes a hatch 30, through which the camera cutting introduces the cutting device 13 is located inside the spent fuel Assembly 1. In the hatch 30 is provided boarding belt 31, second tapered annular projection 25 of the cutting device 13. Thanks to that introduced in the camera cutting the cutting device is located vertically, making it easier to process segments of the lower mounting means 11. And the combined use of an annular protrusion 25, the landing zone 31 and a clamping unit 29 provides rigid fixation of the cutting device 13 in the camera cutting 21. It is obvious that the clamping means 29 is advisable to place the camera cutting as close to the cutting location. On the one hand, allows to increase the reliability of fixing of the cutting device and to eliminate the bend of this unit when a segment of the lower mounting means, and, on the other hand, allows to reduce the service area of the arm 27 and to reduce the size of the observation window 28.The pool 22 (Fig.6) is provided with a support means 32 (shown conventionally), which is in the process of cutting the spent fuel assemblies is mounted a cutting device 13. In addition, the pool sniadecki belt, similar planting belt 31 that is located in the camera cutting.To reduce the weight of the device cutting the lower part of the canister 16 (Fig.7) made in the form of a pipe 34, on the upper end of which has a flange 35 spaced along the perimeter shaped notches 36 (Fig.8), and the upper part of the case 15 is made in the form of a pipe 37 and is rigidly associated guide rods 38 (Fig.4). The opposite ends of the guide rods 38 are placed in the disk 39 which surround the pipe 34 below the flange 35. Three of the guide rod 38, evenly spaced around the circumference passing through the shaped cutouts 36, provide the directional movement of the parts of the case 15 and 16 relative to each other. These rods together with three other rods 40 ensures the preservation of the upper beam rods 2 from accidental contact beam rods during transportation in the cutting device. The rods 40 are evenly circumferentially shifted by 60oin relation to the guide rods 38. The upper ends of the rods 40 are rigidly connected to the pipe 37, and their opposite ends are placed in the disk 39.Basic unit 17 (Fig.11) is designed as two unbalanced levers 41, provided with a base poverhnostyah 41 strive to turn around the axes 47 and a position in which the inside of the tube 34 are partially only the base surface 42 of these levers. Therefore, construction of the lower part of the canister 16 as the transfer arms 41 from the free state to the working is carried out automatically by the fuel Assembly when exposed to the bottom of the tip 9 of the Assembly on the base surface of these levers.Basic unit 17, it is advisable to put in a removable glass 45, which is connected to the pipe 34 and the bottom of the canister 16 with clamp connections (Fig. 12), made for example in the form of a bayonet lock 46. The control node 17 removable glass allows you to have multiple reference nodes, which correspond to a certain type of bottom tip of the fuel Assembly. With the appropriate changes to the configuration of the base surfaces and ledges unbalanced levers is achieved as secure grip with the bottom tip, and constant for all assemblies, the position of the lower mounting means from the end of the lower part of the case, this simplifies the process segments of the lower mounting means.Clamping the stop 18 is mounted for movement along the longitudinal axis of the socket 37 of the upper part 15 of the canister 14 and provided with means the s. It is quite clear that the fixation device 47 is advisable to make in the form of captive bolts (Fig.10), and clamping the stop 18 to provide radial projections 48 and the nozzle to provide a return grooves 49. This provides a measure of the azimuthal position of the clamping of the stop 18 on the pipe 37 and simplifies the process of mounting the stop on the pipe.Funnel 19 (Fig.13) with a collet grip 20 is made in the form of glass 50, resting on the upper end of one of the bundle of fuel rods, aligned and located inside of the Cup 50 of the hollow cylinder 51 and rod 52. To the lower end of the hollow cylinder 51 is attached springy split sleeve 53 collet grip 20 and to the lower end of the rod 52 attached to the control rod 54 (Fig. 14, 15), which is in the process of their movement interacts with the inner surface springy split sleeve 53. At the opposite end of the rod 52 is made screw 55, which engages with a nut 56. The screw 55 is provided with a means (not shown), precluding it from spinning, but not preventing its longitudinal movement. Nut 56 is made in the hub of the bevel gear 57, concatenated with another toothed wheel 58. A gear wheel 58 has an arm rotation is 51. The housing 60 has a fungus 61 gripper cable trolley (not shown) of the cooling pool 22. When you install a funnel 19 on the end of a bundle of fuel rods of the spring sleeve 53 is inside the frame tubes 6, and its upper part with arm rotation 59 is located above the surface of the cooling pool 22. The length of the funnel, corresponding to several meters, corresponds to the thickness of water protection, ensuring safe operation of the operator by the cutting of the exhaust Assembly, and its design provides easy entry collet grip the inside of the frame tubes, the diameter of which is equal to 12 mm, This is achieved in that the hollow cylinder 51 is provided with two centering belts 62 and the flange 63, and at the upper end of the Cup 50 is fixed detachable plate 64. The upper centering spigot 62 is separated from the flange 63 at a distance, providing at the time of installation of the funnel 9 at the end of the unloaded beam rods, initial alignment of the Cup 50 beam rods, and then move the collet grip 20 inside the frame tubes 6.The location of the support means 32 in the storage pool selected from the calculation that the upper ends of both bundles of fuel rods in position (Fig.1B and Fig. 1G) were on the same level (Fig.14) that allows forecastle spent fuel assemblies is performed in the following sequence. Starting position: the cutting device 13 is in the cooling pool 22 and is located on the tool suspension 33. The seat ring 24 located in the upper part 15 of the case 14, is located in the boarding belt suspension means 33. The cutting tool has a strictly vertical position. This position corresponds to the position depicted in Fig.6E. Cable trolley basin shutter (not shown) of the spent fuel Assembly to be cutting, rises above the pool excerpts and transferred to the cutting device 13. The suspension means 33 is located along the line of movement of the cable truck pool shutter 22. When the cable trolley will occupy a position above the cutting device, it will be stopped and the spent fuel Assembly is lowered into the cutting device. In the process of moving spent fuel assemblies inside the lower cutting tip 9 of the fuel Assembly 1 is in contact with the base surface 42 unbalanced levers 41 and carries them turn to the contact of the projections 43 with the outer surface of the lower tip 9. Thus, the bottom of the spent fuel assemblies will be fixed in the cutting device for the lower n is igna part 16 of the case 14 (Fig.11).All of the above actions for spent fuel Assembly are carried out using remotely controlled equipment.After the spent fuel Assembly is installed in the cutting device and the active part, i.e. the bottom 3 and top 2 bundles of fuel rods will be at the desired depth, and above bundles of fuel rods of the water layer provides the necessary biological protection, all subsequent operations in the storage pool are made by the operator, located on the working platform (not shown) located in the placement means a suspension 33. Grip (not shown) cable trolley down from the suspension 12 of the fuel Assembly. Then, the cutting device is mounted presser emphasis 18, it radially spaced tabs 48 combine with mating grooves 49 of the socket 37 and after pressing stop will come into contact with the upper tip 8 of the fuel Assembly 1, carry out the fixation of the clamping stop using fixation devices 47 in the upper part 15 of the canister 14. Thus, to be cutting the fuel Assembly 1 is securely fixed in the cutting device 13 (Fig.4).Further, the cutting device 13 together with the fuel Assembly is Tapered annular ledge 25 of the landing ring 24 comes in contact with the seat belt 31 of the hatch 30 and the cutting device 13 has a strictly vertical position in a suspended state (Fig.5). Then using a clamping device 29 is rigid fixing of the cutting device 13.The cutting head 26 is cut off the lower mounting means 11 and the arm 27 is cut off, the fastening means is placed in a container of waste (not shown). Given clamping device 29, using a cable trolley cutting device is transferred into the pool 22 and is installed in a vehicle suspension 33 (Fig.6A).Then using a cable trolley is removed bearing rod 7 and together with the upper tip 8 and the suspension 12. Exempt fixation means 47 and carry out the removal of clamping the stop 18 (Fig.6b), and in its place installed a funnel 19 (Fig.13). Funnel for fungus 61 is transferred to the cutting device and falls on the upper end of a bundle of fuel rods 2 using the same cable trolleys. In limbo funnel its upper centering spigot 62 is in contact with the bottom end plate 64. So when dropping funnel first comes in contact with a bundle of fuel rods of glass 50. After a glass of 50 rests on the upper end of a bundle of fuel rods 2, will begin to move down the hollow cylinder 51, and with it the collet grip 20. Moving down will continue until the frame tube 6.During the rotation of the arm 59 movement through a pair of bevel gears 57 and 58 and screw a couple formed by a nut 56 and a screw 55, will move up rod 52 and the control rod 54. Last, entering into contact with springy split sleeve 53 (Fig.15), will provide the clamp to the inner surface of the frame tubes 6 of the upper beam rods 2. Next, cable trolley upper beam rods 2 with the hopper 19 may be removed from the cutting device 13 (Fig.6b). The upper beam of the fuel rods is transferred to the location covers for bundles of fuel rods and installed in a transport container (not shown). The next operation is to set the cutting device on the supporting means 32. The cutting device 13 in a known manner is suspended from the cable cart and is mounted on the carrier means 32 of the lower part 16 of the case 14. When lowering the cutting device 13 cable trolley is folded due to the directional movement of the upper part 15 of the canister 14 with respect to its lower part 16 (Fig.6g). The result of this operation the upper end of the lower beam rods 3 will occupy the same position relative to the suspension means 33, and the upper end of the upper beam rods 2 (Fig.14).Remove n is CCA fuel rods 2, using the same tools (Fig.6D). Then using a cable trolley cutting device 13 is transferred and installed in the vehicle suspension 33, where it occupies the initial position (Fig.6E).Thus, the cutting device according to the invention implements a method, intended for cutting fuel assemblies.The method of cutting according to the invention, provides cutting fuel assemblies, allows us to simplify the method of cutting and to improve its security. In addition, the inventive method allows to reduce the dimensions of the cutting chamber, and more productive to use the volume of the cooling pool.The design of the cutting device can simplify the process of its manufacture, to reduce its weight. Furthermore, the design of the cutting device allows the best way to be reconfigured for individual differences undressed fuel assemblies.The patented design of the cutting device eliminates any destruction of spent fuel assemblies in the process of moving the cutting device, and in the process cuts the lower mounting means. In addition, the patented design of the cutting device makes it easier to work operationa on the drawings and described above, is only possible preferred implementation. However, there may be used and various other options regarding the shape, size and arrangement of individual elements. For example, shown in the drawings and described above parts and components can be replaced by an equivalent. Thus, the support means may be in the form of lifts, which are located coaxially to the vehicle suspension. But all these changes should not go beyond the essence of the volume of the invention, formed in the application of patent claims. 2 4 6 8 10 12 1. The method of cutting the fuel assemblies of a nuclear reactor, including installation and fixation Assembly in the device for cutting, remove the lower mounting means and removal under a layer of water of the fuel rods, wherein the fuel Assembly is set up and fixed in a folding box, while removing the lower mounting means are produced in the camera cutting in air atmosphere, and removing the supporting rod, the upper and lower beams rods perform in the storage pool, and to remove the supporting rod and the upper beam rods foam hung in the storage pool, and before removing the lower beam rods osushestvljali Assembly of a nuclear reactor, contains a tool for installation and fixing of fuel assemblies and means for disassembly of the fuel Assembly, characterized in that the means for mounting and fixing the fuel Assembly is made in the case of two moving one relative to the other one posted on the pencil case clamping means.3. The device according to p. 2, characterized in that the clamping means is made in the form of a self-locking between the reference node located at the bottom of the case, and the pressure stops at the top of the canister, and the canister equipped with an additional funnel with located along the longitudinal axis of the collet grip, thus clamping the fence and funnel made vzaimootmenyaemy and collet gripper is mounted for movement along the axis of the funnel.4. The device according to p. 3, characterized in that the lower part of the case made in the form of a pipe, the upper end of which has a flange located at its perimeter scalloped cutouts, and the upper part of the case made in the form of pipe and rigidly associated guide rods passing through the shaped cutouts flange and lower flange of the guide rods placed in the disk covering the pipe.5. The device according to p. 3, characterized in that savetype, interacting with the bottom tip of the fuel Assembly.6. The device according to PP.3 and 4, characterized in that the presser emphasis is mounted for movement along the longitudinal axis of the nozzle upper part of the case and provided with a means of fixing the nozzle and radially spaced protrusions, interconnected with the responsible grooves of the socket.7. The device according to PP.3 and 5, characterized in that the self-locking anchor node is located on a removable cups, attached to the pipe bottom part of the box with quick coupling.
FIELD: nuclear power engineering.
SUBSTANCE: compaction involves cutting members into fragments using electroerosive destruction of member wall by pulse spark-arch discharges emerging between member and electrode. In addition, high-temperature treatment in oxidizing medium, in particular vapor formed, is carried out. Cutting and heat treatment are accomplished in water.
EFFECT: simplified procedure and increased safety.
FIELD: nuclear power engineering; handling radioactive wastes and spent nuclear fuel assemblies disposed in floating or coastal stores.
SUBSTANCE: proposed method used in particular for dismounting spent defective fuel assemblies disposed in store of floating technical depot includes removal of shielding plug from charging port of swivel slab combined with one of concentrically arranged rows of subchannels in tube plate holding fuel assemblies and detection of all defective fuel assemblies in this row. Upon removal of shielding plug swivel stab is rotated, charging port is aligned with head of box holding defective fuel assembly, and annular drilling is made in tube plate body through this port through depth exceeding weld penetration in tube plate, inner diameter of this drilling being slightly greater than outer diameter of bushing. After that box holding defective fuel assembly is separated from tube plate by blasting through its thickness value followed by its lifting from subchannel together with bushing over height of about 0.8 m from bottom edge of box bushing to top plane of swivel slab. Then auxiliary snap ring is fitted onto cylindrical surface of box, outer diameter of this ring being slightly greater than that of bushing, whereupon box is moved back downward and placed in same subchannel of tube plate. After that charging port of swivel slab is sequentially placed above each box holding defective fuel assembly in this row, and all above-described operations are resumed. Upon completion of all these operations all disrupted boxes are extracted one after the other together with bushings and auxiliary snap rings through charging port. Such method takes minimal time for extracting all defective fuel assemblies from floating technical deport store and ensures essential (by several times) reduction in gamma-ray dose absorbed by personnel and reduced escape of radionuclides into environment due to reduced time taken for auxiliary operations associated with specific process equipment installation on, alignment, and removal from working position.
EFFECT: reduced process time, enhanced safety for personnel.
2 cl, 8 dwg
FIELD: nuclear power engineering.
SUBSTANCE: proposed process of recovering fuel assemblies of water-moderated water-cooled reactors incorporating damaged fuel elements, such as leaking ones, includes removal of detachable top nozzle, detection of leaking fuel element, and installation of new fuel element or displacer. Leaking fuel element is extracted by knocking its lower end cap out of bottom spacer grid applying force of not over 140 kgf followed by its pulling applying force not over 30 kgf. Installation of new fuel element or displacer in different areas of fuel assembly needs maximal forces depending on fuel burn-up. This process makes it possible to reduce probability of leaking fuel element destruction in the course of its extraction and damage to new fuel element or displacer can during its installation.
EFFECT: enhanced fuel burn-up due to increasing yield upon replacing leaking fuel elements by new ones in fuel assembly.
FIELD: nuclear power engineering; water-moderated and water-cooled reactors.
SUBSTANCE: proposed device designed for repairing faulty fuel assemblies where damaged and unsealed fuel elements are detected has gripping means for installing fuel element or displacer incorporating grip operating mechanism. The latter is made in the form of kinematically enclosed cable system whose cable is rigidly fixed with gripping means and sequentially engages upper fixed roller, upper movable roller, frictional hauling drum, intermediate roller, and lower fixed roller. Upper movable roller is secured on one end of rocker arm whose other end is joined with load; intermediate roller is disposed above frictional hauling drum and connected to force transducer. Such design of device makes it possible to reduce damage probability to unsealed fuel elements in the course of their extraction and installation, to reduce damage to cladding outer surfaces of new fuel elements or displacers, and to enhance nuclear fuel burnup.
EFFECT: reduced damage probability, enhanced yield of fuel assemblies upon replacement of unsealed fuel elements.
4 cl, 1 dwg
FIELD: nuclear physics.
SUBSTANCE: invention relates to methods of preparing for regenerating nuclear fuel from irradiated fuel elements. Elements made from stainless steel - heads, tail pieces, guide channels for absorbing elements - are separated from the fuel assembly. The fuel assembly is taken for embrittlement of the fuel element cladding. Embrittlement is carried out in enclosed space in air at temperature ranging from 900 to 1200°C. Further, the brittle cladding is mechanically broken down and fuel is removed, as well as the broken down fuel element cladding and other elements of the fuel assembly. The method is characterised by that, air in the enclosed space is enriched with nitrogen until attaining content of oxygen in the air ranging from 5 to 10 vol %, and heating is done in an induction magnetic field with frequency ranging from 40 to 100 kHz, in which the remaining part of the fuel assembly is fed right away as a whole or successively in parts. A special case of the method is when elements made from stainless steel are separated from the fuel assembly before taking for embrittlement by tearing the elements away from where they are attached with local induction heating.
EFFECT: increased efficiency of spent nuclear fuel and increased environmental safety.
FIELD: power industry.
SUBSTANCE: method for performing initial processing stage involves putting of reactor core material to the plant, crushing of fuel particles into fragmented component parts with destruction of their coating by passing electric discharges, and separation of fragmented component parts. Plant includes liquid volume and is equipped with device for generation of electric discharges in this liquid. If reactor core material includes matrix material and fuel particles ingrained in it, then according to version of invention, the method involves additional putting of reactor core material to the second plant, passing of the second electric discharges and separation of fuel cores from coatings and/or residual matrix material. At that, liquid volume of the second plant is less than that of the first one.
EFFECT: invention allows minimising formation of toxic and explosive dust, and reducing energy consumption.
SUBSTANCE: storage box for carrying pipes and/or fuel rod rods of spent nuclear fuel, comprising a housing with a bottom in which an assembly of tandem-connected frames is mounted, at the ends of which there are fastening elements, according to the claimed solution, each frame includes a central rib with a conical shell, having a stepped bottom, and at least one guide shell. The central rib is divided into two parts and has a longitudinal hole in the zone of the guide shell.
EFFECT: increased reliability due to the prevention of bending of the central assembly element.
9 cl, 7 dwg
SUBSTANCE: invention relates to the technology of loading and unloading a fuel assembly (FA) by a loading/unloading machine (LUM). The method for reloading the fuel assembly includes unloading the fuel assembly from the reactor installation to the box by means of a LUM and moving it to the pool of cassette holding to a place of storage free of charge, or moving the fuel assembly from the place of unimpeded storage of the pool of cassette holding in the container and further loading it into the reactor unit; the pencil is vertically immersed in the water of the pool for holding the cassettes to a depth at least equal to the height of the fuel assembly, fix it fixedly in the soak pool to asset, and the movement of the fuel assembly from the pencil into the pool or from the pool into the pencil is carried out through a longitudinal section in the pencil case under the water of the pool of cassette holding.
EFFECT: invention makes it possible to increase the rate of loading of the fuel assembly from the reactor to the BVK and back.
7 cl, 1 dwg